Production of Acetylene and Acetylene-based Chemicals From Coal

Review pubs.acs.org/CR

Production of Acetylene and Acetylene-based Chemicals from Coal Harold Schobert* Schobert*

The EMS Energy Institute, The Pennsylvania State University, University Park, Pennsylvania 16803, United States 6. Conclusions Author Information Corresponding Author Notes Biography Acknowledgments References

1757 1757 1757 1757 1757 1758 1758

1. INTRO INTRODUCT DUCTION ION

Acetylene has been known since the mid-19th century, when it was discovered by Edmund Davy in Ireland and later studied extensively by Marcellin Berthelot in France. The triple bond in acetylene acetylene,, and the fact that acetylene acetylene is thermody thermodynamic namically ally unstab unstable, le, give give acetyl acetylene ene a very very rich rich chemi chemistr stry, y, with with many many appli applica catio tions. ns. The accide accidenta ntall disco discover veryy of calci calcium um carbid carbide, e, produced from coal or coke and limestone in an attempt to prepare calcium metal, and the recognition of the reaction of calcium carbide with water to form acetylene, opened a route to the large-scale production of acetylene. In the 20th century, the two two gian giants ts in the the �eld of acety acetylen lenee chemis chemistry try were were Julius Julius Nieuwland, at Notre Dame University in the United States, and Walter Reppe, at I.G. Farbenindustrie and BASF in Germany. Their extensive studies, along with contributions from many others, created a role for acetylene as a vital feedstock for the production of commodity chemicals. Acetylene, along with the byproduct tar from metallurgical coke plants, were the two pillars of the organic chemical industry to about the middle of the 20th century. The global availability of inexpensive petroleum after about 1950 led to the development of a variety of petrochemical processes, especially based on ethylene. This was a factor in the steady displacement of coal tar and acetylene by petroleum- or gas-de gas-deriv rived ed feedst feedstock ocks. s. As a feedsto feedstock ck for produc productio tionn of chemicals, acetylene increased in imp im portance after the Second World War and peaked in the 1960s.1 In 1960, world acetylene production was 10 million metric tons. 2 By the early 1990s, annual annual worldwide worldwide production had declined to about half that 2 value, and currently currently only several several hundred hundred thousand thousand metric tons are made, mostly from sources other than coal.

CONTENTS 1. Introduction 2. Production of Acetylene 2.1. 2.1. Indi Indire rect ct Prod Produc ucti tion on via via Calc Calciu ium m Carb Carbid ide e 2.2. 2.2. Direct Direct Produc Productio tion n via via Arc Plasma Plasma Reacti Reactions ons 2.2.1. Eff ects of Coal Composition 2.2.2. Eff ects of Reaction Conditions 2.2.3. Yields and Selectivity 2.2.4. Pilot-Scale Testing 2.3. 2.3. Alte Altern rnat ativ ives es to the the ArcArc-Pl Plas asma ma Proc Proces esss 2.4. Other Methods 3. Puri�cation and Handling of Acetylene 3.1. Puri�cation 3.2. Handling Acetylene 4. Acetylene as a Fuel 5. Conversi Conversion on of Acetylene Acetylene to Commodity Commodity Chemicals and Materials 5.1. Acetaldehyde 5.2. Acetic Acid and Acetic Anhydride 5.3. Acetylene Tetrabromide 5.4. Acrylic Acid 5.5. Acrylonitrile 5.6. Aromatic Hydrocarbons 5.7. Alkynes 5.8. 1,4-Butanediol 5.9. Carbon Black 5.10. Chlorinated Solvents 5.11. Ethanol 5.12. Ethylene 5.13. Heterocyclic Compounds 5.14. Isoprene and Chloroprene 5.15. Lewisite 5.16. Norbornadiene 5.17. Polyacetylene 5.18. Propargyl Alcohol 5.19. Resins 5.20. Vinyl Acetate 5.21. Vinyl Chloride 5.22. Vinyl Esters and Ethers 5.23. Vinyl Fluoride © 2013 American American Chemical Society

1743 1743 17 1744 44 1745 174 5 1745 1746 1747 1748 1748 1748 1748 1749 1749 1749 1750 1750 1751 1751 1752 1752 1752 1752 1752 1752 1753 1753 1754 1754 1754 1754 1755 1755 1755 1755 1756 1756 1756 1756 1757

2. PRODU PRODUCTION CTION OF ACETYLENE ACETYLENE

The �eld of coal liquefaction is divided into indirect processes (coal to synthesis gas to liquids) and direct processes (making liquids straight from the coal). Acetylene production from coal can be thought of in an analogous fashion. Indirect production of acetyl acetylene ene involv involves es using using coal, coal, or coal-d coal-deri erived ved coke, coke, to Special Issue: 2014 Chemicals from Coal, Alkynes, and Biofuels Received: May 21, 2013 2013 Published: November 20, 2013 1743

dx.doi.org/10.1021/cr400276u | Chem. Rev. 2014, 114, 1743 −1760

Chemical Reviews

produce calcium carbide and then making acetylene from the carbide. The direct process involves various ways of making acetylene directly from a coal feedstock, without an intermediate step of calcium carbide.

Review

aggregates, rather than the batch operation of a traditional coke oven.13 Along the same line, lignite has been carbonized with calcium hydroxide or calcium carbonate at 900 −1400 °C to form an aggregated solid that is then fed to an oxygen-thermal furnace for calcium carbide production, as discussed further below.14 Methods have been developed to take advantage of low-rank coal feedstocks for calcium carbide production, as alternatives to the more expensive anthracite or coke. One such method includes the partial combustion of some of the coal in the furnace charge.15 The most recent involves the conversion of low-rank coal to a process middle coke containing ≈87% carbon.16 This material is mixed with calcium oxide and heated electrically, but with the addition of some oxygen to the furnace. Combustion of a portion of the process middle coke reduces the electricity consumption and helps to heat the charge. Calcium car bide formation in a plasma reactor has also been demonstrated.17 In the context of modern chemical technology, calcium carbide production has the negative characteristics of being an energy-intensive, long-residence-time batch process involving the handling and feeding of solids. Furthermore, the severe reaction conditions result in a relatively short working life for an expensive electric furnace. Electricity consumption is appro ximatel y 3.3 kW · h/kg of calcium carbide produced. 8 ,16,18 ,19 Despite these disadvantages, some 12 million metric tons of calcium carbide were produced in China in 2006.15 This represents by far the greatest share of worldwide production, which has been estimated to be >15 million metric tons/year.20 Growth rates in calcium carbide demand are forecast to be about 1 −2% annually in the United States and western Europe but 8−10% in China.21 Commercial calcium carbide is available in various grades and particle sizes. The best-q uality material produces 288 L of acetylene/kg of carbide.10 Acetylene is produced by the reaction of calcium carbide with water.1 ,2 ,6 ,11,22 Details of the generating eq uipment and its operation are provided in the early literature6,11 and have not undergone fundamental changes in the years since. The reaction can be eff e cted in so-called wet or dry generators.8 The wet generator uses an excess of water, in at least a 6:1 ratio of water to carbide; 23 more recent data suggest ratios in the range 7−9 t of water/t of calcium carbide.16 Calcium hydroxide is produced in a water slurry as byproduct, at a rate of 2.8 t of Ca(OH) 2/t of acetylene.1 The dry generator is run with a near-stoichiometric quantity of water and produces a pourable powder of calcium hydro xide, any excess water being evaporated by the heat of reaction.2 The largest dry generators have an output of ≈3750 m3/h, equivalent to 32 000 t/year.2 The acetylene yield amounts to 1 t per 3.1 t of 80% pure calcium carbide.8 A portion of the byproduct calcium hydroxide could be recycled to carbide production 16 or could have markets in the agricultural sector as fertilizer and in chemical industries as, for example, raw material for cement production. Recycle is limited to a maximum of ≈60%, to avoid accumulation of impurities in the furnace. 8 Of the two types of generators, the wet system is considered to be safer to operate,24 presumably because the excess water helps dissipate the heat of reaction. The reaction of calcium carbide with water is highly exothermic. If no cooling were used, the heat of reaction could raise the temperature of the reacting mixture to 700 ° C.23 Temperatures in this range could trigger further exothermic

2.1. Indirect Production via Calcium Carbide

Calcium carbide belongs to the family of carbide compounds known as acetylenides, which can be considered to be salts of the C22− anion. Numerous elements are known to form acetylenides, including all of the alkali and alkaline earth elements, the metals of groups 11 and 12 of the periodic table, and some of the lanthanides. 3 Calcium carbide is the only one to have achieved large-scale commercial pro duction. Friedrich Wo discovered calcium carbide in 1862. 3 Supposedly, the hler ̈ �rst synthesis of calcium carbide from calcium carbonate and coke was the unintended outcome of an attempt to obtain metallic calcium by carbothermic reduction of a calcium compound.4 Production of calcium car bide in an electric arc furnace goes back at least 120 years.5 Details of Willson s discovery and other 19th-century work on calcium carbi de and acetylene production are reviewed by Thompson. 6 The importance of Willson s work, relative to the earlier studies of Davy, Wohler, and Berthelot, is twofold: it was the �rst synthesis of calcium carbide that could be applied commercially, and the product was a nearly pure, crystalline material. 7 The highly endothermic reaction of calcium oxide with metallurgical coke occurs in an electric furnace with three So electrodes at temperatures of 2000−2300 °C.1 ,8 derberg ̈ Other carbon sources can be used; however, the two that appear to be most suitable are metallurgical coke and anthracite.9 The reaction can be written as

“

’

’

CaO + 3C ⇄ CaC2 + CO

Production of 1000 metric tons (t) of calcium carbide requires 875 t of calcium oxide and 650 t of carbon, usually in the form of anthracite or coke. 10 Calcium carbide formation begins at temperatures above 1600 °C; below this temperature, the reaction runs from right to left as written above, and carbon monoxide will decompose the carbide. 3 Calcium carbide and calcium oxide form a eutectic at 1630 °C.9 At temperatures >2200 °C, calcium carbide will begin to react further with calcium oxide to produce calcium metal and carbon monoxide. 3 The furnaces operate with 100 −250 V alternating current and a current density in the electrodes of <10 A/cm2.8 Molten calcium carbide is tapped from the furnace into crucibles. There is a substantial production of byproduct gas, primarily carbon monoxide, amounting to about 400 m 3/t.8 In the early years of the industry, this gas was allowed to burn inside the furnace; in more up-to-date installations, the gas was collected and used as a fuel.8 The furnace charge can be a loose mixture of the calcium oxide and carbon source (e.g., anthracite) charged in powder form. It is important for these materials to have sulfur and phosphorus contents as low as practically possible, to limit the amounts of hydrogen sul �de and phosphine impurities in the acetylene.11 Alternatively, the feed can be formed into briquettes, incorporating the reactants in stoichiometric proportions with a hydrocarbon or carbohydrate binder in small amounts. Aggregates of calcium oxide and bituminous coal provide a third option; in this case, the mixture is �rst coked in a standard byproduct recovery coke oven and then fed hot into the arc furnace. 12 A subsequent modi�cation of this third approach allowed for continuous production of the 1744

”


Chemical Reviews

reactions of the acetylene. If air is present in the reactor, the worst-case outcome would be an acetylene−air explosion. Nowadays acetylene made via the calcium carbide route is primarily used as a fuel for oxyacetylene welding and cutting torches, with the notable exception of its use in China for manufacturing vinyl chloride monomer (discussed below). Calcium carbide production is limited to locations that have both cheap electrical energy for operating the furnace and ways of handling and disposing of the calcium hydroxide byproduct. Nevertheless, possible future limitations on petroleum supply  whether real or stemming from geopolitical events could be overcome in part by relying on carbide-based acetylene with coal as the carbon source, despite the accompanying signi�cant economic and environmental issues. Wartime restrictions on petroleum resulted in nearly 90% of the acetylene used in the German chemical industry being made from calcium carbide. 25 Barium carbide, made from barium carbonate, has been suggested as an alternative to calcium carbide. 9 The advantage claimed, relative to calcium carbide, is that the barium compound could be produced in a coal- �red furnace at about 1650 °C, not requiring the use of a high-temperature electric furnace with its attendant high energy costs. 9 Speci�cally, one route to barium carbide involves heating the carbonate with a carbon source and magnesium: BaCO 3 + 3Mg + C → BaC2 + 3MgO.6 However, the production of barium carbide and its subsequent hydrolysis to acetylene are more complicated than with calcium carbide, such that the barium-based process was never commercialized. Lithium carbide is also an alternative starting material.26 Electrolytic decomposition of the lithium hydroxide or oxide provides lithium, which can be recycled by reacting again with coal to regenerate the carbide. Over the years, process improvements have been made, including reuse of the calcium hydroxide formed when calcium carbide is reacted with water, recovery of carbon monoxide from the carbide furnace, minimizing other emissions from the furnace, and reduction of heat losses. 23 Nevertheless, negative factors, including the very large electricity requirement, which dictated the siting of large carbide plants near sources of inexpensive electricity, and the problems of handling large quantities of solids, outweighed the perceived bene �ts of the carbide process. China is now the largest producer of calciu m carbide, with most of it going to acetylene production.27 Production of acetylene from pyrolysis or steam cracking of petroleum fractions accounts for most of the acetylene used nowadays.

Review

a plasma, in which the thermal decomposition of coal is very rapid. The temperature of the arc is estimated to be 10 000 −15 000 °C.33,34 Because acetylene is thermodynamically more stable than other hydrocarbons at temperatures >1200 °C, reaction in a plasma o ff ers a route to direct production of acetylene from coal. Compared to the indirect route, reaction of coal in a plasma or arc process o ff ers the advantages of an overall simpler process scheme and less impact on the environment.35 Work on plasma conversion of coal to acetylene is continuing in China.36,37 The process has been scaled up to a 2-MW pilotplant reactor38 and then to a 5-MW reactor, for which a useful model is available. 39 The 5-MW reactor is thought to be the largest arc-plasma pyrolysis reactor in the world. 40 2.2.1. Eff ects of Coal Composition. Acetylene yield is inversely related to coal rank, with coals of higher volatile matter content (i.e., of lower rank) providing higher yields.27 ,33,41 ,42 It is proposed that acetylene formation is a two-step process, involving �rst the rapid thermal decomposition of the coal into volatiles and solid (char, coke, or soot) and then reaction of the volatiles in the plasma, accounting for the actual formation of acetylene. 33,43 Rank also impacts the formation of byproduct coke. Tests with Chinese coals showed that anthracite had low tendency for formation of coke and adhesion of coke particles to the reactor walls, w hile bituminous coals had signi �cant coking and adhesion.44 This same rank relationship might be expected to be observed at much lower temperatures and heating rates as well. Thermodynamic modeling indicates that two properties impact acetylene yield: the volatile matter content, which has a positive eff ect, and the oxygen content, which diminishes acetylene formation with concomitant increase in carbon monoxide yield.45 Both of these parameters decrease with increasing rank. Qualitatively, coals of high volatile matter but low oxygen content give the best yields of acetylene. 46 Rather, a coal of about 80% carbon and 12% oxygen gives a better acetylene yield.45 Other work has suggested 25 −44% volatile matter and <9% oxygen [on a dry ash free (daf) basis] as optimum.47 Coals in this volatile matter range have produced acetylene yields of 17−22%.35 Related work using a solvent extract from coal, the extract having 43% volatile matter, resulted in about 24% acetylene yield.48 The suggested optimum volatile matter range has been narrowed to 32− 39%.43 (The high acetylene yield from a coal of 33% volatile matter was noted above.) Coals of >37% volatile matter should ideally contain <13% oxygen.49 The key problem arising from the formation of carbon monoxide, that is, a higher oxygen content in the feed coal, is that carbon incorpor ated in the monoxide is unavailable for formation of acetylene. 47,49 This is illustrated in Figure 1. The competitive, and unwanted, formation of carbon monoxide accounts for the fact that lignites, despite their high volatile matter contents, produce only modest yields of acetylene.43 After passing through an optimum of acetylene formation in the rank range corresponding to ≈30−40% volatile matter, yield then decreases at higher ranks.50 A few reports claim that no correlation of acetylene yield with volatile matter exists.51 The interplay of volatile matter and oxygen content is illustrated by tests on four coals of di ff erent ranks.52 In this work, a high-volatile A bituminous coal of 38% volatile matter and 8% oxygen provided the highest acetylene yield, better than

2.2. Direct Production via Arc Plasma Reactions

Production of acetylene via pyrolytic routes takes advantage of the fact that acetylene is the thermodynamicall y sta ble form of hydrocarbons at temperatures above ≈ 1200 ° C28 ,29 and that its free energy of formation decreases at higher temperatures. 30 However, even under these circumstances acetylene is unstable with respect to decomposition to carbon and hydrogen, thus requiring that residence times during pyrolysis be e xtremely short and that the pyrolysis products be cooled rapidly. 30 It has been questioned whether the acetylene produced in experiments using lasers, shock tubes, or plasmas is a true primary pyrolysis product from coal or arises from secondary reactions.31 Berthelot may have been the � rst to observe the formation of acetylene when an electric arc is stuck, by use of carbon electrodes, in a hydrogen atmosphere. 32 The ionized gas forms

“

1745

”


Chemical Reviews

Figure 1. Eff ect of volatile matter content [moisture ash free (maf) basis] on conversion of carbon to ( ) acetylene and to (---) carbon monoxide, based on data from Bittner and Wanzl. 43

Review

Figure 2. Dependence of carbon conversion to ( ) acetylene and to

(---) carbon monoxide on ash yield, dry basis, based on work of Bittner et al.50

a high-volatile C bituminous coal with higher volatile matter, 43%, but also higher oxygen, 15%. Both were superior to a lignite of 54% volatile matter and 22% oxygen. The lowest acetylene yield was obtained from an anthracite of 4% oxygen, but only 8% volatile matter. Plasma pyrolysis of a Polish brown coal (for which the oxygen content was not reported in the original literature but can reasonably be presumed to be high for coals of this rank, that is, some 20−25%)53 show ed formation of acetylene and carbon monoxide in 100:77 ratio.54 Perhydrous coals show a di ff erent dependence on volatile matter. For example, a perhydrous British coal of 46% volatile matter gave a 38% yield of acetylene (equivalent to conversion of 46% of the carbon in the coal). Some reports claim that the inorganic components of coal have no eff ect on acetylene formation.41,45 However, these �ndings contradict other work that showed an in �uence of the ash value, acetylene yield being inversely related to ash value. 50 The apparent relationship of acetylene yield with ash was attributed to the eff ect of oxygen being released from the decomposition of mineral matter and reacting with carbon to produce carbon monoxide. 49,50 ,54 Figure 2 shows a relationship of ash value to acetylene and carbon monoxide yields. The mineral matter content would aff e ct the energy requirement per unit acetylene yield, since the minerals w ill be heated right along with the carbonaceous part of the coal. 41 With respect to the heteroatoms, oxygen forms primarily carbon monoxide, especially above 1227 °C;54 ,55 sulfur produces primarily carbonyl sul�de, especially between 727 and 1527 °C , along with some hydrogen sul�de and carbon disul�de;45,54 and hydrogen cyanide represents the main nitrogen-containing product. 33 ,45,55 ,56 Tests with a series of four British coals showed that carbon monoxide formation was quite close to the amount that would ha ve been predicted on the basis of oxygen content of the coals, 57 con�rmed by a study on six Chinese coals. 49 Addition of nitrogen to the reactor increases the yield of hydrogen cyanide at the expense of acetylene,33 suggesting that, as in formation of carbon monoxide, there is a competition for available carbon. Coal-derived liquids have been shown to produce a gaseous product that is 35% acetylene in a submerged-arc reactor. 48 2.2.2. Eff ects of Reaction Conditions. On the basis of thermodynamic modeling of the reactions of Chinese coals, a hydrogen atmosphere would give the highest acetylene yield,

followed, in order of decreasing yield, by argon and nitr ogen.45 However, the yields reported in this work, ≈10%,45 are signi�cantly lo wer than conversions of 35−40% reported by other authors.33,47 ,56,58 Use of an argon−hydrogen mixture substantially increased acetylene yields relati ve to reaction in pure argon, for example, from 15% to 40%. 52 Compared to reaction in pure argon, the introduction of hydrogen, up to a maximum of 50% in the mixture, improves acetylene yield, in part by retarding the decomposition reaction C 2H2 ⇄ 2C + H2.51 On the other hand, hydrogen concentrations >50% in an Ar/H2 mixture have been argued to reduce acetylene yield by reducing the bulk plasma temperature. 51 The highest acetylene yield, 60% (corresponding to conversion of 74% of the carbon in the coal) was achieved with a British coal of 33.4% volatile matter in the 90:10 Ar/H2 atmosphere. 57 A 40% conversion of the carbon in coal to acetylene was achieved by reaction in a 90:10 argon/hydrogen plasma.33,56 Nonetheless, it is argued that an abundance of hydrogen in the reactor atmosphere enhances conversion of coal to acetylene. 59 Acetylene yield in a hydrogen atmosphere is 3 times greater than from a comparable reaction performed in argon. 60 The importance of hydrogen is attributed to its role in retarding the decomposition of acetylene.47 These reports are consistent with a doubling of acetylene yield in a 90:10 argon/h y drogen plasma compared to the yield obtained in pure argon. 56 The yields of acetylene, and corresponding energy consumptions, vary considerably among reports in the literature. Thermodynamic analysis suggests optimum temperatures for acetylene production at atmospheric pressure in the range 3200−4200 ° C.55 In practice, reaction temperature >1400 ° C is important.2 High temperature is critical; plasma treatment at temperatures <1000 °C favors methane formation rather than acetylene,61 even at very rapid heating rates. 62 The 2- and 5MW pilot-scale reactors in China run at about 3200 °C.40 The extent of reaction depends greatly on particle size. 33,34 ,52 Small particle size is important.27,41 Particle size must be <200 μm, preferably ≤50 μ m.33 ,63,64 As particle size increases, coking becomes more of a problem;44 the solid carbon is not reactive in hydrogen.65 The outer surface area of the particles is recommended to be in the range 0.5 −2.0 m2/cm3.47 Coals of high �uidity, as measured by the Gieseler test,53 appear to 1746


Chemical Reviews

produce particles that shrink, or even burst, in the plasma, further reducing the size of the reacting particles.43 The decrease in acetylene yield with increasing particle size is consider ed to be due to ine ffi cient heating of the particles,27 ,33,41 or to inadequate quenching of the product gases, or possibly to both factors. 33 Heat-transfer rate limits the temperature rise and extent of coal devolatilization.66 Mathematical modeling of heat-transfer processes inside coal particles shows that a decreased heat-transfer coe fficient betw een the particles and hot gas reduces the devolatilization rate.67 Heat and mass transfer between coal particles and surrounding gas is the rate-limiting step in acetylene production.38 These e ff ects become more noticeable at particle diameters >80 μm.67 High yields of acetylene require slow feed rates57 and �ne particle sizes, ideally ≤ 50 μ m.33,58 Both conversion of coal and acetylene yield decrease as the coal feed rate is increased.28,33 ,35 ,68 Coal conversion appears to approach an asymptotic limit with increasing feed rate, while acetylene yield decreases monotonically as a function of increasing feed rate. 35 The eff ect of coal feed rate is illustrated in Figure 3 for the Avco laboratory-scale reactor; the speci �c numerical values would diff er for reactors of other sizes, but the trend would be the same.

Review

residence times are inversely proportional to the cu be root of the speci�c outer surface area of the coal particles. 47 Energy consumption has been estimated to be 2 −3 kW ·h/kg for acetylene production, on the assumption that the reaction proceeds via the breakdown of aromatic ring systems.58 However, the actual energy consumptions are reported to be much higher, estimated to be possibly as great as 100 kW ·h/ kg,58 though values so high as this do not seem required. Values of power requirements in the range of 1 −10 kW ·h/kg (4000− 40 000 kJ/kg) have been suggested.47 More recent work suggests that the best (i.e., lowest) practical values would be on the order of 20 k W ·h/kg, with acetylene yields of 20−30% at these conditions.35 The Hu (discussed below) ls ̈ process 70 operates at 8 kW ·h/kg of coal. Data for a Canadian bituminous coal sho w a speci�c energy requirement of 10 kW ·h/kg of acetylene;43 compara ble to the value of 13 kW ·h/ kg of acetylene reported earlier,71 and comparable to other work reporting values of 11−15 kW ·h/kg of acetylene.74 It would seem reasonable to expect a 35% yield of acetylene on a daf coal basis with an energy consumption of 9 kW ·h/kg.58 Quenching of the gases leaving the reactor should be nearly instantaneous,27,43 ,58 ,75 on the order of milliseconds.28 ,76 R apid quenching of the product gases is important, 2,28 ,41,46 ,51,76 ,77 to retard the decomposition of acetylene to the elements or to other hydrocarbons. If allowed to cool slowly, hot acetylene can revert to tar and oil in about 2 s. 78 Water or cold liquid hydrocarbons can be used as quenching media.47 ,76 This requirement for rapid quenching is a consequence of the fact that acetylene can rapidly decompose to the elements or combine to form higher hydrocarbons unless promptly brought down to near-ambient temperatures. Therefore, quenching is a general issue for high-temperature acetylene-formation processes and is not unique to formation of acetylene from coal in arc-based processes. As an example, similar issues exist with formation of acetylene via the partial combustion of methane. 79 2.2.3. Yields and Selectivity. The yield of acetylene from the arc-plasma process depends on numerous factors of coal composition and of speci �c choices of reaction variables. Not surprisingly, numerical values of yields reported in the literature vary widely, over an order of magnitude. Further, some papers report yields on the basis of, say, kilograms of acetylene produced per kilogram of carbon reacted, while others use kilograms of acetylene per kilogram of coal. These complications aside, it seems reasona ble to expect acetylene yields of ≈ 35−40% on a daf coal basis, 58,71 with a suitable coal feedstock and optimum reaction conditions. The products are only gases and solid; no tars are formed.33 ,41,51 ,54,56 ,57 ,69 The lack of tar formation may be due to the fact that the aromatic components of the volatiles contribute to the formation of carbon deposits in the reactor. 80 A process has been disclosed that incorporates a second-stage reactor for gasi�cation of the residual solid, producing synthesis gas. 71 In addition to being a potential feedstock for gasi �cation, the residual carbon could also be burned to raise steam for electricity generation.40 The best selectivity (i.e., the proportion of acetylene relative to the total hydrocarbon gases in the product ) is about 95%, based on tests with a suite of 10 Chinese coals,35 in agreement with earlier work with British coals. 33,56 Unlike the dependence of yield on volatile matter (discussed above), selectivity does not appear to relate to volatile matter content, an eff ect that is attributed to variations in coal structure. 27

Figure 3. Eff e ct of coal feed rate on acetylene yield, based on data

from the Avco laboratory-scale reactor. 77

Contradictory reports indicate that feed rate had no signi�cant eff ect on acetylene yield34 ,52 ,66 but attributed this to poor mixing of the coal particles with the plasma, resulting in insufficient heating of the particles. (Mixing e fficiency between the coal particles and hydrogen stream has an important in�uence on the release of volatiles.)38 With increased feed rate, the extent and rate of byproduct coke formation increase. 44 A higher coal feed rate corresponds to longer heating times and a lower �nal temperature of the coal particles, causing a lower yield of volatiles and longer time for complete devolatilization.67 ,69 Re sidence times are on t he or d er o f m i ll i se c onds,2,40 ,43,63 ,64 ,70 ,71 optimally <2.5 ms,72 with a heat-up rate of about 1 ms to,33 at most, a few milliseconds.73 Short residence times help maximize yields of acetylene.57 Optimum 1747


Chemical Reviews

2.2.4. Pilot-Scale Testing. Modi�cation of the Hu ls ̈ process to operate on coal has been tested at pilot-plant scale. Acetylene yields of up to 35% were obtained, depending on the speci�c coal used. 2 General aspects of operation, such as residence times, the need for product quenching, coal particle size, etc., are similar to those described in the previous section. An electric arc process, related to the Hoechst −Hu ls ̈ process 2,28 ,71,77,81 discussed below, was tested by Hu ls ̈ and by Avco. Pulverized coal is fed to a hydrogen plasma arc. The best yields of acetylene are about 35%, depending on the nature of the coal feedstock. Compared to the processes that use gaseous or liquid hydrocarbons as feeds, the direct use of coal is more complicated, because of slag produced from the inorganic components of the coal and because of the need to separate various byproducts containing nitrogen, sulfur, and/or oxygen that derived from the presence of these elements in the coal. Residence times are 0.1 −20 ms at 2000 °C, af ter which the product must be quenched rapidly to <400 °C.82 The major technical problems appear to be the energy balance (i.e., the energy input to the arc) and the treatment of the gaseous product stream to separate the acetylene and recycle hydrogen to the reactor.83 A methane-rich gaseous feed has also been tried as the reacting medium.84

Review

The decline in funding for research and development in synthetic fuels, chemicals, and materials from coal some 20 years ago seems to have ended most concerted eff orts to scale up the direct coal-to-acetylene processes mentioned above, as well as investigation of other possible routes from coal to acetylene. Coal-to-acetylene research is continuing in China up to the present; most of the citations to work of the past 10 −15 years refer to work being done in China. 2.4. Other Methods

Because of the problems with calcium carbide production mentioned above, most acetylene production today relies on other routes. These do not involve coal but are mentioned brie� y here to complete the discussion of acetylene production. Further details are available in several sources.1 ,2 ,8 ,23 ,89 The feedstocks discussed in this subsection could, in principle, be made from coal, though doing so would result in an exceptionally cumbersome route to acetylene. Thermal or steam cracking processes of ethane, propane, or their mixtures that are run at high severity to maximize ethylene production also produce some acetylene as byproduct. Propane cracking gives a yield of about 2% acetylene. 1 The Kureha process, using superheated steam from combustion of methane/hydrogen mixtures, produces a 23% yield each of acetylene and ethylene at 2000 °C.2 The plant operates with contact times of 3−10 ms.8 A � ow sheet and additional process details are available.8 If the acetylene is desired as a product, it can be absorbed from the gas stream into such solvents as N methylpyrrolidone or dimethylformamide. 1 The latter solvent can dissolve up to 32 cm3 of acetylene/cm3 of solvent at 25 ° C and 0.1 MPa.90 If the acetylene is not intended to be a separate product, it can be hydrogenated to ethylene. A block �ow diagram of an ethane or propane cracking process that includes hydrogenation of acetylene is given by Chenier.91 The Wulff process involves pyrolysis of methane in a furnace of which the interior is a lattice of bricks. 1 ,23 The bricks are preheated to 1300 ° C by burning a portion of the gas; then the feed is passed through under pyrolysis conditions. These two operations are then repeated by having the gas � ow through the furnace in the opposite direction. Each step takes approximately 1 min, requiring a 4-min cycle. The gaseous product is about 33% acetylene and 67% eth ylene.1 Additional details, including a �ow sheet, are available. 8 The Wulff process has also been operated with naphtha as a feedstock, but apparently no plants are currently running with this feed. Further details on cracking of hydrocarbon liquids to acetylene and coproducts are available.92 The Wulff process is accompanied by signi �cant soot formation; most plants based on this process are now closed. It has been suggested that the methane source could be coal-bed methane,9 thus, in a sense, making this a coal-based route to acetylene. Remarkably, it is also suggested that the carbonaceous byproduct from conversion of methane to acetylene could be used as synthetic coal. 93 The Hu ls ̈ arc process involves pyrolysis of hydrocarbon feeds in electric arcs, in which the temperature of the arc is estimated to be 20 000 °C.2,23 As with processes based on electric arcs and coal feedstocks, pyrolyses of other hydrocarbons also have contact times of milliseconds70 and require a rapid water quench to drop the temperature of the exiting gases to ≈250 30 °C. Acetylene and ethylene are produced in approximately 2:1 ratio, the acetylene yield being 1 t per 1.8 t of feed, or about 55%.2 The related Hoechst −Hu ls ̈ process involved using hydrogen, preheated to ≈3500 °C in an electric arc, as a

2.3. Alternatives to the Arc-Plasma Process

Shock-tube heating of bituminous coal, of 40 μm particle size, at 0.4−3.7 MPa, 475−875 °C, and 1.3−2.0 ms residence time, showed a steady increase in acetylene yield with pyrolysis temperature.31 Laser irradiation of Pittsburgh seam high-volatile A bituminous coal produced gaseous products in which acetylene was the dominant hydrocarbon. 84 This work used a 1.7 J ruby laser. Acetylene amounted to about 20% of the product; the gas in highest concentration was hydrogen, at 45%.84 Use of a 10-J laser in vacuum resulted in 91% of the gaseous hydrocarbons being acetylene (no information was given on the amount of hydrocarbons in the total gaseous product).84 The coal rank eff ects on acetylene yield from laser pyrolysis are similar to those discussed for arc-plasma pyrolysis. The best yields appear to be from coals in the middle of t he rank range, for example, around high-volatile bituminous.85 Acetylene yield from high-volatile bituminous coals is a factor of about 15 higher than the yield from anthracite. 85 Pyrolysis of Kentucky high-volatile bituminous coal in a microwave oven at 2 Torr produces acetylene, along with methane, ethane, and ethylene , but quantitative yield and selectivity data were not given.86 Acetylene has been produced from the reaction of activated carbon with water in a microwave reactor.87 Although this work focused on the use of activated carbon, it would be interesting to determine the feasibility of using high-carbon-content coals (i.e., anthracites), since such coals are not optimum feedstocks for the arc-plasma reaction. An approach much diff erent from the plasma processes involves high-temperature, high-velocity gas reactions. 88 In this case, a hot gas stream, envisioned to be at 1650 −2500 °C, is accelerated to 150−1200 m/s through a series of nozzles. Bituminous or subbituminous coal, at particle size <75 μm, is entrained in the gas for residence times of 2 −30 ms. As with plasma processes, a very rapid quenching of the product gases is necessary, <2 ms. Tests with a Kentucky bituminous coal showed that about 8% of the carbon in the coal was converted to acetylene. However, it appeared that the acetylene concentration in the product gas, which is mostly steam, carbon monoxide, nitrogen, and hydrogen, is quite dilute. 1748


Chemical Reviews

heat-transfer agent;2 apparently this process has been tested in a pilot plant but never commercialized. It was claimed that almost any hydrocarbon feed, up to and including crude oil, could be accommodated. The extraordinary energy consumption required for this process is illustrated by data for the plant in Recklinghausen, Germany, which used medium naphtha as feedstock. Operating with 19 f urnaces, the plant produced 120 000 t of acetylene per year. 8 ,70 Its energy consumption of 1440 GW ·h was estimated to be equivalent to the annual electricity consumption of a city of 400 000 people.8 The residual coke was said to be very reactive and could represent a commercially interesting byproduct of the process. 70 Controlled partial oxidation of methane at approximately 1500 °C leads to acetylene.22,23 The Sachssee process is one variation.1,2 ,23 Other processes have been developed by BASF.8 ,23 The reaction is “

Review

Speci�cations and standards for acetylene diff er somewhat among diff erent countries. As a rule, acetylene to be used as a fuel, in metal-cutting torches for example, must be about 98% pure in the United States. 89 Acetylene to be used as a feedstock for chemical manufacture has higher standards of purity. As one example, the requirements in India for carbide-derived acetylene of so-called quality A is 99.0 vol % acetylene, with allowable impurities of 0.15% hydrogen sul�de, 0.06% phosphine, 0.001% arsine, and 0.10% ammonia. 10 Quality B acetylene is also 99.0 vol % acetylene but di ff ers in terms of impurity limits of 0.08% phosphine and 0.0001% arsine.10

”

3.2. Handling Acetylene

Details of the safety issues of handling acetylene on an industrial scale and engineering approaches to saf e handling are covered in the excellent review by Gannon et al.89 In this paper, only a few points are raised to illustrate the concerns. Aside from the economic issues that currently favor use of ethylene rather than acetylene, this is the other major factor militating against revival of large-scale production of chemical products from acetylene. A principal concern in working with acetylene, both in the laboratory and at commercial scale, is its tendency to explo de when under pressure, when compressed to ≥0.2 MPa.97 Tedeschi 23 warns of the fact that people can work with acetylene in apparent safety for many years, but an explosion could occur at almost any time due to equipment failure or human error. At room temperature, acetylene is thermodynamically unstable with respect to decomposition to carbon and hydrogen. Its decomposition liberates 224 kJ/mol; the heat liberated drives the pressure increase. If no heat loss is assumed, the pressure could increase by a factor of 12; however, the decomposition proceeds so rapidly that a detonation occu rs, reaching pressures 200 times greater than the initial pressure. 98 Furthermore, as the temperature of the system increases, the pressure at which acetylene will explode decreases. 98 The procedures that appear to represent the best safety practices are to dilute the acetylene with an unreactive gas, such as nitrogen or carbon dioxide, or to minimize the amount of free space in the reaction system, for example b y �lling voids with Raschig rings or similar packing material. 98 German experience shows that acetylene cannot be shipped safely in 50−300 mm pipes, even at 0.1 −0.2 MPa, without explosion risk.23 However, use of <50 mm pipes packed with steel or ceramic Raschig rings or small-diameter tubes allowed acetylene to be shipped 80 km in safety. For pipes of <25 mm, several hundred kilopascal pressure could be used. A mixture of acetylene with 50% nitrogen could be piped at 0.3 MPa. At 0.1 MPa and 15 ° C, acetylene is soluble in acetone to the extent of 25 cm3 of acetylene/cm3 of acetone; at 1.2 MPa, the solubility at this temperature increases to 300 cm3/cm3 of solvent.90 This solubility is the basis of a common way of handling and storing acetylene with good safety. A cylinder �lled with some type of porous solid thoroughly saturated with acetone has become a standard method for handling and transporting acetylene. Acetylene is often handled in steel tanks by dissolving it in acetone; the tanks also contain some type of porous �ller such as diatomaceous earth (kieselguhr), pieces of �rebrick, or, in years past, asbestos. Under these conditions, acetylene can be handled safely at pressures to about 1.5 MPa. Because it is difficult to ship acetylene easily, it is advantageous if large-scale users would be colocated with, or at least near, the source of acetylene. 18 Although the calcium

6CH4 + O2 → 2C2 H 2 + 2CO + 10H 2

In this process, some of the hydrogen was used as fuel to help maintain the necessary reaction temperatures of 1500 °C. The product contains about 10% acetylene. 1 Methane pyrolysis in the presence of steam at 1200 ° C also produces acetylene, with a coproduct of hydrogen. 94 This reaction is 2CH4 → C2 H 2 + 3H 2

Carbon monoxide and part of the hydrogen could also be used as feed for various applications of synthesis gas, such as production of alcohols via the synthol or oxyl syntheses. 58 A related process uses the controlled partial oxidation of m ethane and coal, preferably subbituminous or bituminous rank. 76 3. PURIFICATION AND HANDLING OF ACETYLENE 3.1. Puri�cation

Crude acetylene from these processes will contain a variety of impurities, which usually need to be removed before the acetylene can be used. Separation of entrained, partially or unreacted particles can be e ff ected in a cyclone.71 ,95 Puri�cation of acetylene is done in a multistep process, each step of which is similar to other conventional or better-known gas cleanup operations. Ammonia can be removed in a sulfuric acid wash. 2 Hydrogen cyanide and hydrogen sul �de are remov e d in an acid-gas treatment by scrubbing with amines,76 ,95 or alkyl pyrrolidone solvents.95 Hydrogen sul�de can also be removed in a Claus plant.71 Other alternatives involve oxidizing sulfur and phosphorus compounds in chlorine water or sulfuric acid. 2 Carbon dioxide can be absorbed in aqueous sodium hydroxide. This caustic wash can also remove carbon disul �de. Alternatively, acetylene can be separated from the other products by dissolution in selective solvents such as methanol or N -methylpyrrolidone,71 ,76 tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, acetone, or kerosene. 2 ,76 A fully integrated system that includes solvent cleanup and recycling, as well as methanation of the tail gases and use of the methane as a co-feed to the acetylene production reactor, has been disclosed.96 Crude acetylene has a characteristic odor that is due to small quantities of impurity gases such as phosphine, arsine, and hydrogen sul�de. These impurities derive from calcium phosphate or sulfate that may have been present in the limestone used for production of calcium carbide. 3 ,9 ,11 These impurities must be removed for many of the chemical syntheses from acetylene, because of their e ff ects in poisoning catalysts. 30 1749


Chemical Reviews

carbide route to acetylene has the several disadvantages discussed above, the potential exists to ship calcium carbide, rather than acetylene, over some distance and generate the acetylene itself on site. If the acetylene were to come from calcium carbide, the carbide plant in turn needs to be located near a source of cheap electricity. Despite these legitimate safety concerns, it must be said that acetylene was, and is, handled in large quantities by the chemical industry worldwide for many decades, including at elevated pressures.

Review

5. CONVERSION OF ACETYLENE TO COMMODITY CHEMICALS AND MATERIALS Acetylene is a versatile feedstock for production of chemical products or carbon materials, because it can undergo several kinds of reactions. These include formation of carbanions by loss of one or both hydrogen atoms; addition of one or two reactants across the triple bond; participation in Diels − Alder reactions as a dienophile; and dimerization to vinylacetylene, trimerization to aromatic compounds, or polymerization to polyacetylene. 19 Acetylene can, in principle, be used to manufacture any product that can otherwise be made from ethylene.105 Acetylene derivatives off e r a possibility of polyfunctionality in the primary product, which is generally not the case with alkene derivatives.106 In many cases, acetylene-based routes to commodity chemicals have been operated on an industrial scale at some time, somewhere, during the past century, so that the know-how for such operations exists. This section focuses on the use of acetylene to produce chemicals, monomers, and carbon materials that are, or have been, of commercial importance. Table 1 summarizes estimated

4. ACETYLENE AS A FUEL

Acetylene is the fuel used in the oxy acetylene torch, used for cutting or welding metal.11 ,22 ,90,99 Its usefulness in this application comes from its ability to produce �ame temperatures of ≈3000 °C. Acetylene has a lower heat of combustion than either of the related compounds ethylene or ethane but achieves higher �ame temperatures. This is due to the m uch lower heat capacity of the gaseous products of combustion. 100 Complete combustion of acetylene produces 1 mol of water/ mol of acetylene; ethylene or ethane produce 2 or 3 mol of water, respectively. Because less water is formed in the combustion reaction, less of the liberated heat of combustion is needed to raise the combustion products to the �ame temperature. Production of acetylene for welding or cutting is still based on the coal-to-carbide-to-acetylene route and represents one of the last remaining signi�cant markets for coal-based acetylene. The best-known example of the use of acetylene for smallscale illumination was the miner s lamp, which has now been supplanted by electric lamps. Acetylene was also used for domestic or small commercial illuminating applications in locations where neither gas mains nor electric service was available. Examples include acetylene-fueled table lamps and cooking stoves.11 Acetylene lamps w ere used on bicycles, motor vehicles, and railway rolling stock. 11 In these cases the acetylene was produced by reacting calcium carbide with water. Phosphine, which was a common impurity in acetylene produced this way, would burn to phosphorus(V) oxide. In domestic illumination applications in closed rooms, the P2O5 would produce a haze of phosphoric acid in the room. 101 At one time, automated lighting systems relied on acetylene-fueled lights. Prior to World War II, acetylene lamps were used as the light source in about 75% of the world s lighthouses, 4 as well as in beacons for aviation. Extensive information on small-scale use of acetylene as an illumination source, as well as the appliances for its use, is given in the reviews by Thompson 6 and by Pond.11 Acetylene has been tested from time to time as a possible fuel for internal combustion engines. In a spark-ignition engine it appears to o ff er some potential for reduced NOx emissions.102 This potential is outweighed by the tendency for engine knock. That problem, combined with the safety issues of handling acetyleneits wide �ammability limits and a potential for explosive decomposition led to the conclusion that acetylene would not be a practical fuel for spark ignition engines.102 (The explosive limits in air are 3−82%.)103 Acetylene has been tried, apparentl y successfully, as a fuel for gas (not gasoline) engines.11 ,104 It has been claimed to have been successfully tested as a motorcycle fuel.6 The suggestion was made that lique�ed acetylene could be used as a vehicle fuel, 6 remarkable because the grave risk of violent explosions while compressing acetylene have been known for well over a century.

Table 1. Estimated Annual Worldwide Production of Major Commodity Chemicals That Could Be Made from Acetylene

’

compd

annual production (×106 t)

acetaldehyde acetic acid acrylic acid acrylonitrile benzene 1,4-butanediol carbon black (all forms) ethanol ethylene isoprene vinyl acetate vinyl chloride

1 7 1 4.5 30 1 10 850 105 0.8 7 30

annual production for some of the major commodity chemicals that have been produced from acetylene in the past and, in principle, could be made from acetylene again in the future. All of the chemicals discussed in this section, as well as the various consumer products made from them (Table 2), could be produced from coal via acetylene. Today, most of these products are made from petrochemical ethylene and, in the case of ethanol, from biomass resources as well. Table 2 is not intended to be a complete catalogue of products that could derive from acetylene chemistry and, ultimately, from coal. Rather, the examples presented there show how wide a spectrum of everyday substances could, in principle, be made from coal via acetylene. While the chemistry is as practical as ever, as industrial processes these methods are largely obsolete; in almost all cases, coal-based processes have been displaced by alkenes or byproduct acetylene from petroleum or natural gas processing.22 Acetylene also has many interesting uses in laboratoryscale chemistry, for example, in the synthesis of acetylene complexes of transition metals. 3 None of the products of these reactions has, so far, achieved large-scale production, so they are not covered here. Many of the advances in the utilization of acetylene for production of commercially useful compounds are due to

’

1750


Chemical Reviews

immense quantities of shale gas in many parts of the world, or from possible geopolitical maneuvering in global oil markets, remains to be seen.

Table 2. Examples of Consumer Products Deriving from Acetylene-based Chemicals a

consumer product adhesives anesthetic aviation fuel blood plasma extender building siding corrosion inhibitors electrically conducting polymers electrical insulation electrodes (batteries or fuel cells) �ooring fungicides and herbicides hair spray insecticides motor vehicle fuel paint pharmaceuticals photocopying compounds plastics rubber solvents textiles or clothing vitamins

Review

acetylene chemical as source

5.1. Acetaldehyde

acrylic acid, vinyl acetate divinyl ether norbornadiene vinylpyrrolidone vinyl chloride propargyl alcohol polyacetylene

Acetaldehyde production exceeds 1 Mt/year, nowadays almost entirely from controlled oxidation of ethylene. Acetaldehyde serves primarily as a precursor to various other useful chemical products. It also forms a resin by condensation with urea. Hydration of acetylene in the presence of mercury(II) sulfate produces acetaldehyde. 1 ,90,110−112 Early work emplo yed a suspension of platinum in dilute aqueous nitric acid113 or mercury(II) bromide.114 Manganese dioxide has also been used as a catalyst. 115 Reaction conditions are 0.1−0.2 MPa acetylene pressure and 90−95 °C.30 Conversions are about 55% , with unreacted acetylene being recycled to the reactor.30 Vinyl alcohol has been suggested as being the initial product, which undergoes extremely rapid and irreversible enol−keto tautomerism to the aldehyde. 29 ,32 ,111 ,116 It has also been suggested that the intermediate is a mercury acetylide, which is then decomposed by the acid to yield t he desired acetaldehyde and regenerate the mercury(II) sulfate.32 If higher alkynes are used in this reaction, the products are ketones. 107 Traditionally, the reaction was conducted in 18 −25% sulfuric acid at 70 −100 °C.23 In the Gru process, the reaction is nstein ̈ performed in concentrated sulfuric acid at ≤50 °C.32 ,90 It was suggested that a transitory geminal disulfate formed �rst, followed by hydrolysis to 1,1-ethanediol, which in turn promptly eliminated water to produce acetaldehyde.117 An alternative process, developed by what was then the Konsortium fu r̈ elektrochemische Industrie , ran the reaction in a hot solution of dilute sulfuric acid.32 The Montecatini process provides a 95% yield of acetaldehyde, operating at 85 30 The Chisso process also operates at relatively mild °C. conditions, 68−73 °C and ≈0.15 MPa.115 This process has a less complicated �ow sheet than other acetylene-to-acetaldehyde processes, in part due to clever approaches to taking advantage of the heat release during hydration to help in the distillation recovery of acetaldehyde; it also avoids the need for recycling unreacted acetylene, which had been a requirement in other processes. 115 Conversion of acetylene to acetaldehyde in the Chisso process is 96.5%. 115 Although these were once commercial routes to acetaldehyde, they have since been supplanted by the more economical direct ox i dation of ethylene30 ,118 or dehydrogenation of ethanol.30

vinyl chloride acetylene black vinyl acetate, vinyl chloride α -picoline, pyridine, propargyl alcohol

methyl vinyl ether 1,4-butenediol, pyridine ethanol acrylic acid, vinyl acetate acetic anhydride, pyrazole, pyridine, propargyl alcohol N -vinylcarbazole acrylic acid, acrylonitrile, 1,4-butanediol, ethylene acrylonitrile, isoprene, chloroprene 1,4-butenediol, tetrachloroethane acrylic acid, vinyl chloride propargyl alcohol

These products could be made from coal via the carbide or arcplasma routes. a

Walter Reppe and his group, at I.G. Farbenindustrie in the period 1925−1945.106 A good postwar summary of the advances in acetylene chemistry in Germany, mainly due to Reppe and colleagues, is available. 98 These processes are collectively known as Reppe chemistr y. Reppe chemistry encompasses three classes of reactions.107 First, vinylation involves the introduction of a vinyl group, CH 2=CH− , into a compound having a slightly acidic hydrogen atom, of which acetylene is one example.108 Production of acrylonitrile from acetylene and hydrogen cyanide is the most important such reaction on an industrial scale. Second, ethynylation introduces the CHC− group into a molecule. For example, acetylene reacts with formaldehyde to produce propargyl alcohol. Third, carboxylation involves reaction of carbon monoxide and a hydroxyl-containing compound with acetylene. Production of acrylic acid and acrylate esters is an industrially important example. Further details on these reactions are given in the subsections below. Products from Reppe chemistry represented only about 2.5% of acetylene-based chemical production in Germany during World War II.109 Nonetheless, postwar investigation of the German chemical industry identi�ed Reppe chemistry as one of three areas from which the Allies could derive useful knowledge (the others were sy nthetic fuels from coal and production of synthetic rubber). 109 Generally, whatever chemical products or materials can be produced from acetylene can be made more cheaply by use of appropriate alkenes as the feedstocks. In part, this is due to the energy-intensive nature of the carbide, Sachsse, and related processes for making acetylene. A further consideration is that the alkenes are generally easier and safer to handle than acetylene.2 What future impacts may derive from extraction of

5.2. Acetic Acid and Acetic Anhydride

Current annual production of acetic acid is around 7 Mt. Its industrial uses include the production of vinyl acetate, the monomer for poly(vinyl acetate), and cellulose acetate, used in some applications for plastics, such as the frames for eyeglasses. The once-major application of cellulose acetate was for the production of photographic �lm, the market for which largely collapsed with the widespread acceptance of digital photography. Acetic acid production today is dominated by petrochemicals. With the demise of the market for �lm, acetic anhydride �nds its major use in the synthesis of aspirin by acetylation of salicylic acid. Acetylene can be used as starting material for the production of acetic acid.22 ,111 Acetaldehyde is an intermediate in this process; it is catalytically oxidized with air to give the acid.111 Cerium or manganese acetates serve as catalysts. 110 In a further reaction step, acetic acid will add to another molecule of 1751


Chemical Reviews

Review

acetylene to produce acetic anhydride.111 ,119 The addition reaction occurs at 60−85 °C in glacial acetic acid, in the presence of mercury(II) acetate or sulfate as catalyst. The intermediate is ethylidene diacetate, CH 3CH(OCOCH3)2. The diacetate then is converted to the desired acetic anhydride by atmospheric-pressure thermal decomposition at 300−400 119 °C.

into charcoal. 119 The necessary hydrogen cy anide can be made from reaction of acetylene with ammonia. 123 Hydrocyanation of some acetylene derivatives proceeds at 60−120 °C in the presence of tetrakis(triphenylphosphite)nickel(0). 124 The reaction apparently was not tested on acetylene itself nor has been used in industrial practice.

5.3. Acetylene Tetrabromide

Trimerization of acetylene leads to benzene. 6 ,90,107 Historically, the reaction has been performed by � owing acetylene through a tube heated to 600 °C or, qualitatively, a dull red heat. 125 Extensive details of the early work in this �eld are reviewed by Nieuwland and Vogt.90 Various forms of carbon appear to catalyze the reaction. 90 An 80% yield of benzene can be eff ected by trimerizing acetylene in tetrahydrofuran (in which acetylene is highly soluble) in the presence of nickel cyanide and triphenylphosphine at only 70 °C.126 More recent work indicates the conversion of acetylene to a variety of hydrocarbon products, including benzene derivatives, using nickel- or cobalt-modi�ed shape-selective zeolite catalysts and a coreactant (such as a light alcohol) that serves as a hydrogen donor.127 Reaction temperature is 350 °C; under optimum conditions an 85% conversion of acetylene is achieved.127 Aromatization of acetylene in the presence of hydrogen, over zeolite catalysts, provides yields of up to 56% BTX (mixture of benzene, toluene, and xylenes) at 400 °C, along with smaller amounts of C9 and C10+ aromatics.128 Of course, there are easier routes to benzene from coal or coal tar than making acetylene as an intermediate step. Today benzene is produced almost entirely from petrochemical processes, including various petroleum re�ning operations such as steam cracking and catalytic reforming. Most benzene goes to production of other chemicals, including ethylbenzene, the precursor to styrene; cumene, used to make phenol; and cyclohexane, a precursor to nylon. Reppe synthesized an array of benzene derivatives beginning with the cyclization of acetylene. Examples include di- and tricarboxylic acids, di- and tribenzyl alcohols, their corresponding ester and ether derivatives, and hydroaromatic versions of these compounds.129 The Reppe hydroquinone synthesis involves trimerization of acetylene in the presence of carbon monoxide and steam by use of ruthenium or rhodium catalysts. 2

5.6. Aromatic Hydrocarbons

This compound is noteworthy because of its remarkable density, ≈ 3 g/mL. Its high density makes acetylene tetrabromide useful in mineral separation processes in which it is desired to exploit di ff erences in density between a valuable ore and accompanying low-value, or useless, rock. Preparation of acetylene tetrabromide is e ff ected easily by passing acetylene into a solution of bromine in an inert solvent.19 5.4. Acrylic Acid

Acrylic acid is a major commodity chemical, worldwide annual production being over 1 million metric tons. Virtually all acrylic acid production now comes from propylene. Esters of acrylic acid, that is, acrylates, are polymerized to form a large variety of consumer products that includes adhesives, paints, coatings such as �oor polishes, and many kinds of plastics. Acetylene will react with carbon monoxide and water to produce acrylic acid. 2 ,23,120 The reaction is now known as Reppe hydrocarbonylation. Reaction occurs at 220−230 ° C and 10 MPa with nickel bromide catalyst2 or with metal carbonyls.19 ,98 ,121 Selectivities to acrylic acid are about 90%. 2 The BASF process operates at 225 °C and 3−20 MPa in tetrahydrofuran.30 ,119 If an alcohol is used instead of water, the product is an acrylate ester. For example, the use of methanol produces methy l acrylate. In this case, nickel carbonyl is used as catalyst. 18 ,91 ,111 ,119 Major uses of acrylates include the production of coatings and textiles. Reaction conditions are 30−50 ° C and 0.1−0.7 MPa.30 These reactions are examples of Reppe chemistry, of which other examples are discussed elsewhere. A modi�cation of the carbonylation in the presence of water leads to hydroquinone, 2 used mainly as a water-soluble reducing agent. The modi�cations involve increasing the CO:H2O ratio and using higher pressures, up to 90 MPa, and catalysts based on Fe, Co, Ru, or Rh, such as Ru 3(CO)12.121 5.5. Acrylonitrile

5.7. Alkynes

Acrylonitrile is used in production of polyacrylonitrile as well as various copolymers, such as its copolymer with styrene. Polyacrylonitrile (PAN) is the starting material for the production of carbon � bers, which enjoy steadily growing applications in a wide variety of products that range from badminton rackets to rocket motors. The styrene−acrylonitrile (SAN) copolymer is a synthetic rubber. The related acrylonitrile butadiene styrene terpolymer (ABS) is used to make an array of injection-molded plastic items, including the famous Lego bricks. Until the 1970s, the reaction of acetylene with hydrogen cyanide was a commercial route to acrylonitrile.2 ,23,30 At present, the process cannot compete with ammoxidation of propylene.19 This reaction occurs at 80 −90 ° C and 0.1 MPa in the presence of copper(I) chloride− ammonium chloride2 ,119,122 or barium cyanide on carbon 111 as catalysts. The process was developed by Bayer and was used by several large chemical companies up to 1970. 119 An alternative approach, developed by Goodrich, involved a vapor-phase reaction at 500−600 ° C in the presence of sodium hydroxide impregnated

Higher n-alkynes can be produced in the Picon synthesis. Sodium acetylide in liquid ammonia reacts with alkyl chlorides to produce alkynes up to at least 1-hexadecyne. 19,110 An alternative route to sodium acetylide in volves reaction of acetylene with molten sodium at 110 ° C.19 The higher alkynes will undergo many of the reactions discussed elsewhere in this section, producing the corresponding homologous products. 5.8. 1,4-Butanediol

Total worldwide production of 1,4-butanediol from all sources is ≈1 Mt/year. Alternatives to acetylene chemistry for the production of 1,4-butanediol include use of maleic anhydride and propylene oxide as starting materials and a biochemical route from sugar. Possibly the last remaining major application of acetylene in chemicals production, and last major application of Reppe chemistry, is the reaction of acetylene with formaldehyde to produce 1,4-butynediol. 116 The formaldehyde is supplied as its 37% aqueous solution (i.e., formalin). The reaction occurs at 1752


Chemical Reviews

≈100 °C

and 0.1 MPa over copper(I) acetylide catalyst on a magnesium silicate support,1 ,119 in a trickle- bed reactor.2 A copper − bismuth catalyst has also been used.130 The desired product, 1,4-butanediol, is produced by two-stage hydrogenation of the original 1,4-butynediol. The �rst occurs in a liquid-phase reactor at ≈55 °C and 1.4−2 MPa over Raney nickel, followed by reaction at ≈130 ° C and 14−30 MPa over a copper −manganese−nickel catalyst on silica gel.1 ,2 ,119 Alternatively, hydrogenation can be conducted in a trickle-bed reactor at 100 −200 ° C and 20 MPa over copper- or chromiumpromoted nickel catalysts. 2 The selectivity to 1,4-butanediol is about 95%.2 Hydrogenation can be stopped at the 1,4-butenediol stage if catalysts of lesser activity are used, such as iron catalysts or nickel catalysts with iron additives. 2 1,4-Butenediol diacetate reacts with hexachlorocyclopentadiene to produce the insecticide endosulfan or Thiodan. 2 ,19 Most of the production of 1,4-butanediol is used in the manufacture of poly(butylene terephthalate). 19 1,4-Butanediol is useful in the production of tetrahydrofuran, which subsequently is converted to poly(tetramethylene ether glycol). This reaction occurs in the presence of acids that are good dehydrating agents, such as sulfuric or phosphoric acids, at 110−125 °C, with nearly quantitative conversion. 2 The latter compound is a feedstock for producing Hytrel thermoplastic elastomers, polyurethanes (used, for example, in the production of wheels for skates), and Spandex elastomeric � bers.1 1,4Butanediol is also the feedstock for making compounds that have use as solvents or as precursors to solvents, particularly γ butyrolactone and pyrrolidone. γ -Butyrolactone, formed by gasphase dehydrogenation at 200 −250 °C over copper catalysts, 2 can be converted to N - methylpyrrolidone, which has applications as a replacement for chlorinated solvents. Also, pyrrolidone can be converted to N -vinylpyrrolidone, polymers of which are used in such commercial products as hairspray. This reaction occurs with acet ylene at 180 °C in the presence of 2% potassium hydroxide. 122 The subsequent polymerization is initiated by peroxides. Reppe de veloped the conversion of 1,4-butanediol to butadiene.131 Using coal-derived acetylene as the feedstock opened a route to producing useful butadiene-based synthetic rubbers, such as Buna-S, from coal. Commercialization of an alternative route, based on Nieuwland s preparation of vinylacetylene, followed by its conversion to butadiene, stalled because it was estimated that synthetic rubber plants w ould require the entire world supply of palladium for catalysts. 131

Review

Because acetylene is thermodynamically unstable relative to the elements, once reaction has begun, conversion of a cet ylene to carbon black and hydrogen is highly e xothermic.133 The temperature eventually reaches >2500 °C.132 To begin the reaction, a portion of acetylene is burned to heat the interior of the reactor. Once the air supply is shut o ff , thermal decomposition of the acetylene takes over, permitting formation of carbon black. Unlike the feedstocks used in most other carbon black production processes, acetylene is chemically homogeneous. That, combined with the substantial heat liberated by the reaction, results in a product, acetylene black, that is very pure and with a high degree of crystallization relative to other kinds of carbon blacks.132−134 About 96% of the car bon atoms are in aromatic sheets stacked in 6−7 parallel layers. 133 Particle sizes are 40−55 nm.134 Acetylene blacks are used principally as electrical conductors in various electrochemical, plastic, and rubber applications. 133 A major application has been in the production of electrodes for batteries. 19 ,23 Acetylene blacks also have a low degree of chemical reactivity. 132 Processes have been developed to produce acetylene black from other feedstocks, such as via the decomposition of methane in a plasma reactor.135 Acetylene black anodes hav e been evaluated for use in molten salt electrolyte fuel cells. 136 Oxidation rates are not so low as for similar anodes made of graphite or calcined petroleum coke but are better than those for oth er forms of carbon black or various types of activated carbons. 136 Co-pyrolysis of coal with waste tires in an argon −hydrogen plasma can improve the yield of acetylene and the relative volume fraction of acety lene in the product gases, relative to reaction with coal alone. 137 This work involved Chinese coals and styrene− butadiene rubber containing ≈30% carbon black. These results suggest the possibility of designing a process that could regenerate carbon black for tire manufacture by making acetylene from waste tires and coal and using the acetylene as feed for carbon black production. 5.10. Chlorinated Solvents

Production of various chlorinated solvents was one of the �rst large-scale applications of acetylene chemistry. Reaction of acetylene with chlorine produces 1,1,2,2-tetrachloroethane; 23 however, this reaction is dangerous, with the possibility of explosion.110 Many catalysts have been proposed for this reaction, including aluminum chloride ,113 antimony(V) chloride,90 ,110 ,113 and iron(III) chloride.90 Tetrachloroethane can also be prepared by reaction of acetylene with antimony( V) chloride, a discovery attributed to Berthelot in the 1870s. 110 This compound serves as an intermediate in the production of 1,1,2-trichloroethylene. Tetrachloroethane is formed by reaction of acetylene with chlorine, with an excess of the tetrachloro compound serving as diluent. Iron(III) chloride is used as a catalyst. Without the diluent, direct reaction of acetylene and chlorine can lead to the formation of highly explosive chloroacetylenes. Subsequent conversion to trichloroethylene is eff ected by dehydrochlorination in calcium hydroxide slurry at 100 °C or by reaction over barium chloride on carbon as catalyst at 230 −320 °C.23 Trichloroethylene (also known as chlorothene) is used as an industrial solvent in numerous applications, perhaps the highest volume use being as a degreaser for metal surfaces. Years ago it was also used as a refrigerant. It �nds some use as an anesthetic. However, recognition of the many potential environmental impacts and

’

5.9. Carbon Black

Production of all forms of carbon black is a large industry on a worldwide scale, with total production of all types of carbon blacks being about 10 Mt/year, of which ≈95% is used in the manufacture of tires.3 The two general routes to carbon blacks are via incomplete combustion of some hydrocarbon feedstock, giving the so-called combustion blacks or furnace blacks, and via thermal decomposition of a hydrocarbon feed, producing the thermal blacks. Thermal black and furnace blacks represent about 95% of total carbon black production, of which furnace black is ≈90%. Acetylene black is made by thermal decomposition of acetylene. In the Shawinigan process, acetylene is fed to a cylindrical reactor preheated to ≈800 132 Commercial acetylene black is not the same material as °C. the black sooty substance formed during production of acetylene in arc or other high-temperature processes. 1753


Chemical Reviews

likely explains the selectivity of the catalyst.143 Various treatments that decrease the amount of surface hydrogen on this catalyst decrease its activity but increase its selectivity. 141 Higher selectivity can be achieved by alloying palladium with silver.144 Oligomerization on the catalyst surface decreases activity and selectivity.145 Deactivation appears to be due to the build-up of acetylenic species that are permanently retained on the catalyst surface.146 Acetylene can also be eff ective at carburizing the surfaces of palladium catalysts. 147 Palladium supported on multiwalled carbon nanotubes allows for selective hydrogenation of acetylene even in acetylene−ethylene mixtures;148 gold on cerium(I V) oxide also gives excellent selectivity for hydrogenation.149

human health eff e cts has led to trichloroethylene and tetrachloroethane being replaced by alternative solvents in many countries, including the United States. 1,1,2,2-Tetrachloroethylene (also known as perchloroethylene, or perc ) was produced by reacting trichloroethylene with chlorine, to produce pentachloroethane (also known as pentachlor). Pentachloroethane was then converted, via dehydrochlorination, to tetrachloroethylene. This reaction could also be done by use of calcium hydroxide or via a vapor-phase catalytic process.23 This compound has been used widely as a dry cleaning solvent, in which application it has the virtues of being volatile and non �ammable. A related application is as a spot remover from clothing, fabrics, and upholstery. It is also used in some paint strippers. Tetrachloroethylene is also of concern for its environmental and health impacts. Some countries, such as Canada, no longer allow its production. “

”

5.13. Heterocyclic Compounds

1,4-Butanediol can be converted to γ -butyrolactone, which then can be used to synthesize a series of useful compounds, such as pyrrolidone and its derivatives N -methylpyrrolidone and N vinylpyrrolidone, and poly(vinylpyrrolidone).19 N -Methylpyrrolidone is a versatile solvent that has advantages, compared to many other organic solvents, of relatively low toxicity and �ammability. Poly(vinylpyrrolidone), or polyvidone, is another discovery attributed to Reppe. It is a water-soluble polymer with many medical applications, such as a blood plasma expander, as well as more prosaic applications, such as the binder in glue sticks. Pyridine is produced at about 30 kt/year, and is used in the synthesis of pharmaceuticals and agrochemicals (herbicides and insecticides), as well as a solvent. α -Picoline is used to make fungicides and herbicides, as well as vinyl pyridine latex, used as an adhesive for tire cords. β -Picoline is a starting material for the synthesis of vitamin B3. The γ -isomer is used in synthesis of pharmaceuticals. Pyridine and its three monomethylated derivatives (α -, β -, and γ -picolines) can be made b y reaction of acetylene with ammonia at high temperatures; 90 ,122 the product is also referred to as a complex mixture of heterocyclic, basic nitrogen compounds.30,150 Reaction conditions are rather severe for acetylene chemistry: 120−140 ° C, 1.3−1.5 MPa, and 35−74 h reaction time in the presence of zinc and cadmium acetates.30 Diazomethane adds to acetylene to produce pyrazole;90 ,111 this is the only nitrogen compound that will add readil y to acetylene at ambient temperatures and without a catalyst.90 Pyrazole is used in the synthesis of a variety of medicinal compounds. A cetylene reacts with carbazole to produce N -vinylcarbazole.19 Subsequent polymerization yields a photoconducting material, poly(vinylcarbazole), used in photocopying machines. Oxygenated compounds do not appear to form heterocyclic derivatives on reaction with acetylene. 90 Acetylene reacts with pyrite at 280−310 °C to produce thiophene.32 The same product forms upon passing acetylene through boiling sulfur. 90 At least 2000 t of thiophene is produced annually. It is used as a starting material in making various medicinal compounds and agrochemicals.

5.11. Ethanol

Ethanol is an excellent and versatile solvent. It is well-known as a motor vehicle fuel and as an oxygenated additive and octane booster in gasoline. Ethanol can be produced from acetylene in a sequence of reactions involving hydrogenation to ethylene with nascent hydrogen ; dissolution of the ethylene in sulfuric acid to form ethylsulfuric acid, C2H5SO4H; addition of water; and recovery of the ethanol by distillation. 6 In principle, this off ers a route for producing ethanol from coal, though it is difficult to see any advantage to this process relative to the hydration of petrochemical ethylene or fermentation of sugars. “

”

5.12. Ethylene

Under the strained economic situation of the Second World War, there was interest in making ethylene from acetylene. In today s industry, there is no reason to contemplate producing acetylene for the purpose of making ethylene, especially since ethylene is less costly than acetylene. However, the selective hydrogenation of only one of the two double bonds in acetylene provides insight into catalytic hydrogenation processes that might be useful with other alkynes. A good review of early (pre-1945) studies of hydrogenation catalysts is given by Nieuwland and Vogt. 90 Useful thermodynamic data are available to indicate the temperature ranges in which ethane , ethylene, and acetylene are stable in the presence of hydrogen.138 Reaction of a mixture of calcium carbide and metallic zinc with aqueous sulfuric acid produces acetylene and nascent h y drogen, which is said to combine readily with the acetylene.6 Selective hydrogenation of acetylene to ethylene, not all the way to ethane, can be e ff ected over Lindlar s catalyst, palladium on calcium carbonate treated with lead acetate and quinolone.126 Palladium appears to be both the most active and the most selective hydrogenation catalyst, based on a survey of 10 candidate metals (all of the metals of groups 8, 9, and 10, plus copper). 139 Palladium on silica gel shows good selectivity for hydrogenation of acetylene to ethylene without over-hydrogenation .140 Such a catalyst was used during World War II to produce ethylene from acetylene in 90% yield at 200−300 °C.30 Only the �rst π bond, which is the more reactive of the two π bonds in acetylene, is hydrogenated. Such a reaction provides a way for countries de �cient in petroleum but possessing abundant coal reserves to produce ethylene. Palladium on alumina is also an e ff ective catal yst,141 ,142 as are rhodium or/ium on silica gel or alumina. 143 Acetylene and ethylene adsorb on di ff erent sites on the catalyst surface, which ’

’

“

Review

5.14. Isoprene and Chloroprene

”

Isoprene and chloroprene are important in the production of synthetic rubber. 1,4-cis-Polyisoprene has properties very similar to those of natural rubber. Annual production of isoprene is 0.8 Mt. Acetone adds to acetylene at 10−40 ° C and 2 MPa in liquid ammonia, with potassium hydroxide catalyst.2,8 The initial product of this reaction is 2-methyl-3-butyn-2-ol, in yield of about 96 mol %. 8 Selective partial hydrogenation of the primary 1754


Chemical Reviews

Review

densities of ≈39.5 MJ/m3 , compared to such as JP-8 or Jet A.

product yields methylbutenol; the reaction is carried out at 30− 80 °C and 0.5−1 MPa over a palladium catalyst. 8 Subsequent dehydration of this alcohol at 250−300 °C over alumina111 gives the desired isoprene 2 with complete conversion.8 This process was developed by Snamprogetti and operated commercially until the early 1980s; it is sometimes referred to as the SNAM process. 8 For chloroprene production, acetylene is dimerized to vinylacetylene in aq ueous hydrochloric acid with copper(I) chloride catalyst. 2 ,110 ,151 Acetylene conversion is about 18% but with selectivity to vinylacetylene of 90%.2 A second stage of reaction adds hydrogen chloride across the remaining triple bond to produce the chloroprene. The reaction occurs in the presence of copper(I) chloride in hydrochloric acid, at 60 ° C.2 Chloromethylallene , CH2Cl−CH=C=CH2 , has been proposed as an intermediate.110 Selectivity of vinylacetylene conversion to chloroprene is 92%. 2 Acetylene has largely been displaced as feedstock for this process by butadiene. The �rst step of reaction, addition of acetylene to itself in dimerization, is chemically similar to the addition of hydrogen cyanide, mentioned below.10 6 Thus HCC H + H C CH → H2C=CHCCH and HCCH + HCN → H2C=CHC N are formally the same reaction. The intermediate vinylacetylene forms explosive peroxides in contact with air, requiring special safety precautions for running this process. 23 Chloroprene can then be polymerized via a free-radical process to form one of the �rst synthetic rubbers, generally called neoprene, originally a vailable in the United States under the trade name Duprene,110 and in the former Soviet Union as Sovprene.90

≈35

MJ/m3 for fuels

5.17. Polyacetylene

The �rst polymerization of acetylene was eff ected o ver titanium(IV) n-butoxide and triethylaluminum catalyst.30 ,158 Polyacetylene can also be made by a ring-opening polymerization of cyclooctatetraene.159 The cyclooctatetraene can be made from acetylene.160 The early literature on the physics, chemistry, and material properties of polyacetylene is summarized in the monograph by Chien. 158 Alternative catalyst systems include nickel halides mixed with borohydrides or with phospines.30,161 All other metals from groups 8−10 work as well, except compounds of iron.162 Polyacetylene can exist in four diff erent structures.30 Chain lengths are estimated to be 50 −500 nm.163 trans-Polyacetylene is a semiconductor, whereas cis -polyacetylene is an insulator. If the cis form is treated with strong oxidizing or reducing agen ts, its conductivity increases by 10 orders of magnitude.30 Formation of the cis product is favored at low reaction temperatures, −78 °C, whereas reactions at higher temperatures, ≈150 °C, favors the trans product.164 Catalysts containing nickel halide complexes with tributylphosphine also favor the trans form. 165 Room-temperature synthesis is reported to form a polymer with approximately equal contributions from the cis and trans f orms, which is similar to copper in electrical conductivity.30 Potential applications abound in engineering organic molecules with desired electrical properties for use in various solid-state devices.166 Polyacetylene can be produced as �lms,163,167 but these polymers are not able to be processed either in melt phase or solution. Films having Young s modulus of 100 GPa and tensile strength of 0.9 GPa have been reported; these values are roughly comparable to those of Kevlar. Polyacetylene is also a conducting polymer.168 Maximum conductivity was about 2.2 × 104 S/cm,167 comparable to other values obtained for iodinedoped polyacetylene. 169 cis-Rich polyacetylene has a tensile strength of ≈150 MPa.170 Transparent polyacetylene �lm has been prepared with a conductivity of 5000 S/cm after doping with iodine;171 depending on catalyst, preparation method, and doping, values to 16 000 S/cm have been obser ved.172 Values in excess of 100 000 S/cm have been claimed. 173 Other oxidizing agents such as antimony(V) �uoride, or electron donors such as lithium, also cause orders-of-magnitude improvement in the conductivity of polyacetylene.174 Treatment of polyacetylene with �uorine leads to material useful in making gas-separation membranes. 19

5.15. Lewisite

Arsenic(III) chloride adds to acetylene to form the compound ClCH=CHAsCl2 , the basis of the poison gas lewisite, intended to be an even more horri�c replacement for so-called mustard gas [(ClCH2CH2)2S], used in the trench warfare of World War I.90 ,106 ,122 Fortunately, lewisite was never actually used in warfare. Lewisite, mustard gas, and related compounds are vesicants, or compounds whose action includes the extreme blistering of exposed skin. The last global supplies of lewisite were supposedly destroyed in 2012.

’

“

5.16. Norbornadiene

At elevated pressure, acetylene condenses with cyclopentadiene in a Diels− Alder reaction to produce norbornadiene.30 ,122 ,152 Other reaction conditions favor the formation of bicycloheptadiene compounds, some of which may have use as insecticides.153 Norbornadiene has been used in synthesizing complexes for formulating homogeneous catalysts. Dimerization of norbornadiene leads to a compound with the trivial name of Binor-S.154 Hydrogenation of the dimer leads to highdensity aviation fuels. Polynorbornene acts as a solid binder for liquid fuels, for example, gasoline and advanced aviation fuels such as JP-10 and RJ-5.155 The polymer can contain up to 80% of the liquid fuel and still remain as a rubbery solid, useful as a solid fuel for ramjets.155 Cyclopentadiene can be produced by reaction of acetylene with propylene.156 Further, cyclopentadiene can also be recovered from the light fraction of coal tar.157 This suggests the possibility of a route, albeit a long one, from coal to premium aviation fuels such as JP-10, which is pure exo-tetrahydrodicyclopentadiene, and JP-9, a mixture of methylcyclohexane, perhydronorbornadiene, and exo-tetrahydrodicyclopentadiene. These fuels have volumetric energy

”

5.18. Propargyl Alcohol

Propargyl alcohol �nds applications in various chemical products such as corrosion inhibitors. This compound is a useful intermediate in producing various compounds having use as bactericides, fungicides, and for treating infestations of mites.1 Propargyl alcohol is useful in producing vitamins A and E and 2-aminopyrimidine, which is used in the synthesis of sulfadiazine.19 If the reaction of acetylene with formaldehyde, mentioned above, is run at lower pressures, only one molecule of formaldehyde is incorporated, giving propargyl alcohol. 116 (Propargyl alcohol that forms as a byprodu ct in the synthesis of 1,4-butynediol is recycled to the reactor.) 2 Propargyl alcohol can also be hydrogenated in a subsequent step to allyl alcohol. 111 1755


Chemical Reviews

Review

impurities from the acetylene, the hydrogen chloride must be free of chlorine, and no water can be present, since water w ould immediately hydrolyze the vinyl chloride to acetaldehyde.30 A vapor-phase reaction is run at 100−170 °C and 0.3 MPa119 in 30 ,119 Mercury(II) chloride supported on � xed-bed reactors. granular activated charcoal is used as catalyst. 40,119 The � xed bed reactors are basically shell-and-tube heat exchangers, which are packed with the catalyst. Hydrochlorination is highly exothermic, necessitating relatively small reactor size due to the large amounts of excess heat. Recent work indicates process improvements attainable in a two-stage �uidized-bed reactor. 40 ,177 The conversion is up to 99%, with selectivity to vinyl chloride being about 98%. 23 ,177 Recent catalyst formulations are designed to eliminate the use of mercury. A catalyst based on gold, lanthanum, and cobalt on activated carbon provides conversions >90% and selectivity >98%.40 Potassium tetrachloropalladinate catalyzes the hydrochlorination of acetylene in quantitative yield. 178 Although the conversion of acetylene to vinyl chloride is itself a relatively inexpensive process in terms of capital and operating costs, the acetylene feedstock is more expensive than ethylene, so ethylene-based routes to vinyl chloride now dominate in most countries. However, China is interested in coal-based acetylene for vinyl chloride production.179 Some 95−97% of poly(vinyl chloride) produced in China originates from acetylene made from calcium carbide. 21 The most important application of vinyl chloride is in production of the ubiquitous poly(vinyl chloride) (PVC), 18 along with various copolymers, including PVCA. PVC is used to make pipes, so-called vinyl siding for buildings, and insulation on electrical cables. When formulated with plasticizers, such as phthalate esters, PVC can also be used in clothing and furniture upholstery. In many parts of the world, acetylene-based processes have been displaced entirely by those using the cheaper ethylene feedstock. However, production of vinyl chloride monomer from acetylene would still make economic sense in countries with abundant supplies of cheap coal, such as South Africa or China. About 70−80% of the P VC production in China, some 10 million metric tons/year,40 begins with acetylene,15 ,40 of which 90% is produced from calcium carbide.40

5.19. Resins

Acetylene reacts with alkylphenols to produce various resinous materials.98 ,175 One such, originally made by Reppe, was known as Koresin and served as a very e ff ective tacki�er for synthetic rubber. These compounds have molecular masses in the range 800−1100 Da. The starting material for Koresin itself was ptert -butylphenol.175 Matrix resins for graphite-reinforced composite materials can be formulated from polyphenylsulf one and a reactive plasticizer with an acetylenic terminal group.176 The speci�c compound used in this work was 4,4 -bis(3-ethynylphenoxy)diphenyl sulfone. The purpose of the acetylenic groups is to provide sites for facile cross-linking reactions. ′

5.20. Vinyl Acetate

Annual production of vinyl acetate exceeds 7 million metric tons. Virtually all is made currently from ethylene. Most production from acetylene ended some 30 years ago. 19 Vinyl acetate can be made by vapor-phase reaction of acetylene with acetic acid at 170 −250 ° C and atmospheric pressure with a zinc acetate catal yst supported on granular act ivated car bon.2 ,23,119,122 The reactor is a shell-and-tube heat exchanger packed w ith the catalyst. Yield is up to 98% based on acetylene.23 In the liquid phase, this reaction occurs at 60 −80 °C and 0.1−0.2 MPa, with mercury(II) acetate used as catalyst;18 ,90,116,119 zinc amalgam has also been used. 91 As is the case with other acetylene-based routes to vinyl monomers, this process has been almost completely supplanted by ones using ethylene as feedstock, because of the lower cost of ethylene and the storage and handling issues associated with acetylene. Vinyl acetate production data provide remarkable testimony to the swing away from acetylene-based processes. In 1969, 90% of vinyl acetate was produced from acetylene; that �gure had dropped to 10% only six years later, in 1975, and within another � ve years there was no signi�cant production from acetylene.91 Vinyl propionate can be produced in an analogous reaction, starting with propionic acid. 2 Formation of vinyl esters of larger acids, including such fatty acids as stearic and oleic acid, can be eff ected by similar reaction with acetylene with zinc or mercury catalysts. Vinylation of the larger acids is done in the liquid phase, for example, at 1−1.5 MPa and 165 °C in the presence of zinc stearate.2 Acid conversions of 95−97% and selectivities to the vinyl ester of 97% can be achieved. 2 This reaction is sometimes referred to as Reppe vin ylation, discussed in an extensive review by Reppe himself.108 Poly(vinyl acetate) is used in formulation of latex paints, as well as in adhesives and coatings. Products such as wood glue or carpenter s glue, and the white glue used in schools, are made with poly(vinyl acetate). Copolymers of vinyl acetate and vinyl chloride, called poly(vinyl chloride acetate), PVCA, �nd use in the manufacture of �ooring, and, in the past, of phonograph records. The copolymer with ethylene, ethylene vinyl acetate (EVA), is also used in some adhesives, particularly hot glue sticks. EVA also forms the material commonly known as foam rubber, used as padding in sports equipment.

5.22. Vinyl Esters and Ethers

Acetylene reacts with carboxylic acids to produce vinyl esters.1 ,90 These compounds have use as plasticizers in poly(vinyl chloride) or poly(vinyl acetate) formulations. They also can be used to produce materials that serve as substitutes for epoxy resins. Vinyl ethers can be made by reacting acetylene with alcohols in the presence of an acidic catalyst, such as boron tri�uoride.90,107 Ether formation can also be run with basic catalysts , of which potassium hydroxide gives the best results.98 ,103 Reaction conditions are 160−185 °C and 0.7− 2.1 MPa.98 Selectivities up to 95% can be achieved. 2 Divinyl ether �nds use as an anesthetic. Methyl vinyl ether, copolymerized with maleic anhydride, yields a material useful in formulating hair sprays. 19 Phenols are also reactive; phenol itself produces phenyl vinyl ether, which rearranges to o-vinylphenol.103 As noted above, the analogous reaction with isobutylphenol produces a useful adhesive for synthetic rubber products, Koresin. 103

’

5.21. Vinyl Chloride

Annual production of vinyl chloride is over 30 million metric tons, the majority from ethylene. Acetylene reacts with hydrogen chloride in the presence of a mercur y(II) chloride catalyst on activated charcoal support. 2,18 ,22,23 ,25,90 ,112 ,119 The conversion of acetylene is about 97%, with selectivity to vinyl chloride of 98%.2 In addition to removing catalyst-poisoning 1756


Chemical Reviews

Review

continued development of the electric-arc process or on the appearance of some new, signi�cant technological breakthroughs.19 The recent work in China, which is richly endowed with coal, suggests a continuing investment in improving the arc process. The many studies of acetylene chemistry in research laboratories worldwide may lead to exciting new developments in producing useful chemicals from acetylene. Pine29 has indicated that, When world petroleum resources decline, the carbide process based upon coal might become important for the petrochemical industry. A similar concern was voiced by Vollhardt,126 who also pointed out that there were no convenient routes directly to ethylene, propylene, or butadiene from coal but that coal (or coke) can readily be converted to calcium carbide for acetylene production. Julius Nieuwland, one of the great �gures of acetylene chemistry in the early twentieth century, has stated that the possibilities of further research in acetylene derivatives promise great and varied possibilities. Even in the investigation of acetylene itself, we are far from having covered the �eld in an adequate manner. 90

5.23. Vinyl Fluoride

Addition of hydrogen �uoride to acetylene produces vinyl 2 �uoride, the precursor to poly(vinyl �uoride), a polymer desirable because of excellent resistance to weathering. Various catalysts have been used. Supported mercury compounds operate at temperatures ≤150 °C but deactivate relatively quickly; aluminum, tin, or zinc � uorides catalyze the reaction at higher temperatures, 250 −400 °C. Poly(vinyl �uoride) is sold under the trade name Tedlar, a product of Dupont. One application of this polymer is a surface protectant for photovoltaic cells.

“

”

6. CONCLUSIONS

This review has focused on production of acetylene from coal, via the classic calcium carbide route and the emerging arc pyrolysis process, and on production of commodity chemicals from acetylene. There has been, and continues to be, extensive work on the use of acetylene in the synthesis of specialty chemicals or interesting new compounds emerging from laboratory research. Specialty chemicals from acetylene are treated in the useful monograph by Tedeschi, 23 the earlier review by Reppe,108 and the even earlier monograph by Nieuwland and Vogt. 90 Although much has changed in the intervening three decades, particularly with respect to economic and environmental considerations (for example, the hope that it might be possible to utilize excess heat from nuclear breeder reactors for making acetylene directly from coal), the basic chemistry has not changed. There does not appear to have been a detailed economic analysis of chemicals production via coal-derived acetylene at least in many decades. Even 30 years ago it was suggested that such economics would be particularly speculative and convoluted .82 The issues include the ability of coal to compete with other hydrocarbon feedstocks for acetylene production, then the issue of which route to acetylene from coal would be preferred, and �nally the larger question of the competition between acet ylene and ethylene as precursors to chemical production.82 For large-scale commodity chemical production, a change in the relative prices of ethylene and acetylene would be needed for acetylene even to be considered as returning to its former importance. Economic issues regarding the competition between ethylene and acetylene are covered in detail in the monograph by Stokes, 109 albeit with focus on the postwar German chemical industry, and covered more generally by Szmant.19 Possibly, the coal to calcium carbide to acetylene route may off er some advantages in small or niche markets, especially where electricity is inexpensive and byproduct sales of calcium hydroxide would be feasible. There is no question that technologies for the production of acetylene from coal, and for production of an extensive variety of commodity chemicals from acetylene, are well-known and, in many cases, have been demonstrated at commercial scale. There are no technical barriers to making chemicals from coal based acetylene. The issues are primarily economic, especially the price competition with ethylene and the high energy costs for calcium carbide or direct acetylene production, and various environmental concerns. Stokes109 points out that the choice among coal, biomass, or petroleum for chemical production must be made on a country-by-country basis according to the availability of raw materials and various �nancial and technical aspects. The future of acetylene from coal as a large-scale source of materials of industrial importance depends on

“

”

AUTHOR INFORMATION Corresponding Author *E-mail

[email protected].

Notes

The authors declare no competing �nancial interest. Biography

“

”

Harold Schobert is Professor Emeritus of Fuel Science at The Pennsylvania State University, University Park, PA. He also has an appointment as Extraordinary Professor in the Coal Research Section, School of Physical and Chemical Sciences, North-West University, Potchefstroom, South Africa. He has nearly 40 years experience in energy and fuel research, mainly in the conversion of coal to clean synthetic fuels and value-added chemicals or carbon materials. Professor Schobert is the author of about 140 articles in peerreviewed journals, 12 books, and several hundred short papers in conference proceedings or preprints. He has served on numerous energy-related advisory boards or committees at state, national, and international levels. Professor Schobert is a Fellow of the American Chemical Society and a recipient of the Henry H. Storch Award for excellence in fuel chemistry from the ACS Division of Energy and Fuels. ’

1757


Chemical Reviews

Review

(30) Olah, G. A.; Molna r,́ A. Hydrocarbon Chemistry. Wiley: New York, 1995; pp 79, 205, 216, 228, 249, and 455. (31) Howard, J. B. In Chemistry of Coal Utilization , Second Supplemental Volume; Elliott, M. A., Ed.; Wiley: New York, 1981; Chapt. 12. (32) Karrer, P. Organic Chemistry; Elsevier: New York, 1946; p 66. (33) Bond, R. L.; Ladner, W. R.; McConnell, G. I. T. In Coal Science; Given, P. H., Ed.; American Chemical Society: Washington, DC, 1966; Chapt. 41. (34) Graves, R. D.; Kawa, W.; Hiteshue, R. W. Ind. Eng. Chem. Proc. Des. Dev. 1966 , 5 , 59. (35) Bao, W. R.; Chang, L. P.; Lu, Y. K. Process Saf. Environ. Prot. 2006 , 84 , 222. (36) Wang, L. H. China Chem. Rep. 2005 , 16 (18), 16. (37) Du, J. China Chem. Rep. 2006 , 17 (12), 15. (38) Wu, C.; Chen, J.; Chen, Y. Fuel Process. Technol. 2010 , 91 , 823. (39) Yan, B.; Cheng, Y.; Jin, Y. AIChE J. 2013 , 59 , 2119. (40) Yan, B.; Lu, W.; Cheng, Y. Green Process. Synth. 2012 , 1 , 33. (41) Chakravartty, S. C.; Dutta, D.; Lahiri, A. Fuel 1976 , 55 , 43. (42) Ju H.; Klein, J.; Knoblauch, K.; Schro ter, H. J.; Schulze, J. ntgen, ̈ ̈ In: Chemistry of Coal Utilization , Second Supplemental Volume; Elliott, M. A., Ed.; Wiley: New York, 1981; Chapt. 30. (43) Bittner, D.; Wanzl, W. Fuel Process. Technol. 1990 , 24 , 311. (44) Tian, Y. Y.; Qiao, Y. Y.; Xie, K. C. Adv. Mater. Res. 2013 , 634 , 825. (45) Bao, W.; Li, F.; Cai, G.; Lu ,̈ Y.; Chang, L. Energy Sources A 2009 , 31 , 244. (46) Fei, W.; Guo, W.; Yuan, X.; Zhao, T. Plasma Sci. Technol. 2006 , 8 , 307. (47) Peuckert, C.; Baumann, H.; Bittner, D.; Klein, J.; Juntgen, H. Method for Production of Acetylene. U.S. Patent 4,378,232, March 29, 1983. (48) Ladner, W. R.; Wheatley, R. Fuel 1971 , 50 , 443. (49) Yan, B.; Xu, P.; Guo, C. Y.; Jin, Y.; Cheng, Y. Chem. Eng. J. 2012 , 207 , 109. (50) Bittner, D.; Baumann, H.; Klein, J. Fuel 1985 , 64 , 1370. (51) Littlewood, K. Mater. Res. Soc. Symp. Proc. 1984 , 30 , 127. (52) Kawa, W.; Graves, R. D.; Hiteshue, R. W. Reaction of Coal in Argon and Argon-Hydrogen Plasmas; Report of Investigations 6829; Bureau of Mines, U.S. Department of the Interior, Washington, DC, 1966. (53) Van Krevelen, D. W. Coal: Typology − Physics − Chemistry − Constitution; Elsevier: Amsterdam, 1993; pp 258 and 693. (54) Plotczyk, W. W.; Restak, A.; Szymanski, A. Int. J. Mater. Prod. Technol. 1995 , 10 , 530. (55) Griffiths, D. M. L.; Standing, H. A. In Coal Science; Given, P. H., Ed.; American Chemical Society: Washington, DC, 1966; Chapt. 42. (56) Bond, R. L.; Galbraith, I. F.; Ladner, W. R.; McConnell, G. I. T. Nature 1963 , 200 , 1313. (57) Nicholson, R.; Littlewood, K. Nature 1972 , 236 , 397. (58) Berkowitz, N. An Introduction to Coal Technology; Academic Press: New York, 1979; p 240. (59) Chen, L.; Shen, J.; Shu, X.; Fang, S.; Zhong, L.; Meng, Y. Plasma Sci. Technol. 2009 , 11 , 321. (60) Krukonis, V. J.; Gannon, R. E.; Modell, M. In Coal Gasi �cation; Massey, L. G., Ed.; American Chemical Society: Washington, DC, 1974; Chapt. 3. (61) Scott, T. W.; Venugopalan, M. Nature 1976 , 262 , 48. (62) Mentser, M.; O Donnel, H. J.; Ergun, S.; Friedel, R. A. Prepr. Pap. Am. Chem. Soc., Div. Fuel Chem. 1973 , 18 (1), 26. (63) Kim, C. S. Method of Producing Acetylene from Coal. U.S. Patent 4,358,629, November 9, 1982. (64) Yan, B.; Cheng, Y.; Jin, Y.; Cheng, Y. CFD simulation of the reacting � ow process of coal pyrolysis to acetylene in hydrogen plasma downer reactors. Proceedings of 13th International Conference on Fluidization , Gyeong-ju, Korea, May 16 −21, 2010. (65) Li, M.; Fan, Y.; Bao, W.; Guan, Y.; Li, S. Energy Sources A 2006 , 28 , 829.

ACKNOWLEDGMENTS

I am pleased to thank Nita Schobert, Lee Ann Nolan, and Arielle Forrester for their assistance with literature searching and document retrieval. REFERENCES (1) Wittcoff , H. A.; Reuben, B. G. Industrial Organic Chemicals; Wiley: New York, 1996; p 302. (2) Weissermel, K.; Arpe, H. J. Industrial Organic Chemistry ; VCH: Weinheim, 1993; pp 91−100, 114, 118, 161, 214, 221, 226, 287, and 300. (3) Holleman, A. F.; Wiberg, E. Inorganic Chemistry ; Academic Press: San Diego, CA, 2001; pp 784, 798, and 1072. (4) Dull, C. E. Modern Chemistry; Holt: New York, 1936; pp 324 and 326. (5) Willson, T. L. Electric Reduction of Refractory Metallic Compounds. U.S. Patent 492,377, February 21, 1893. (6) Thompson, G. F. Acetylene Gas, Its Nature, Properties and Uses; Thompson: Liverpool, U.K., 1898. (7) Renouf, E. Pop. Sci. Mon. 1899 , 55 , 336. (8) Chauvel, A.; Lefebvre, G. Petrochemical Processes. 1. Synthesis Gas d́ itions Technip: Paris, 1989; pp Derivatives and Major Hydrocarbons; E 119, 303, 327, and 347. (9) Napier, D. H. Br. Coal Util. Res. Assoc. Mon. Bull. 1954 , XVIII , 517. (10) Ascent Supply Chain Consultants Pvt. Ltd.. Calcium carbide. http://www.ascconline.com/img/services/project_report/Calcium_ Carbide_Project_Report_Sample.pdf , . (11) Pond, G. G. Calcium carbide and acetylene. The Pennsylvania State College Chemistry Bulletin, State College, PA, 1909. (12) Becket, F. M. Manufacture of Calcium Carbide. U.S. Patent 1,137,567, April 27, 1915. (13) Becket, F. M. Manufacture of Calcium Carbide. U.S. Patent 1,292,387, January 21, 1919. (14) Kersting, H. J.; Wolfrum, E.; Portz, W.; Strauss, G. Production of Calcium Carbide. U.S. Patent 4,391,786, July 5, 1983. (15) Liu, Z.; Liu, Q.; Li, G. Method and System for Producing Calcium Carbide. U.S. Patent Application 2011/0123428A1, May 26, 2011. (16) Guo, J.; Zheng, D. Ind. Eng. Chem. Res. 2012 , 51 , 13414. (17) Wang, Z.; Jin, Z.; Tian, Z. Plasma Sci. 1996 , 225. (18) Haberstroh, W. H.; Collins, D. E. In Handbook of Industrial Chemistry; Kent, J. A., Ed.; Van Nostrand Reinhold: New York, 1974; p 775. (19) Szmant, H. H. Organic Building Blocks of the Chemical Industry; Wiley: New York, 1989; Chapt. 4. (20) Umeozov, C.; Marrero, T. R. Abstracts of Papers, National Meeting of the American Institute of Chemical Engineers, Pittsburgh, PA, Oct. 28−Nov 2, 2012; Abstract 674b. (21) IHS Chemical. Calcium carbide. http://www.ihs.com/products/ chemical/planning/ceh/calcium-carbide.aspx , 2011 (22) Morrison, R. T.; Boyd, R. N. Organic Chemistry; Allyn and Bacon: Boston, 1973; pp 43, 251, 252, and 454. (23) Tedeschi, R. J. Acetylene-based Chemicals from Coal and Other Natural Resources; Marcel Dekker: New York, 1982. (24) Glatzer, E. Coal to Chemicals: An Alternative Solution to Rising Feedstock Costs. ICIS Chem. Bus. 2006 , http://www.icis.com/ A r t i c l e s / 2 0 0 6 / 0 4 / 0 6 / 2 0 1 2 5 5 5 / c o a l - t o chemicals+an+alternative+solution+to+rising+feedstock.html. (25) Loudon, G. M. Organic Chemistry; Addison-Wesley: Reading, MA, 1984; p 471. (26) Torma, A. E.; Ghosh, J. Coal Sci. Technol. 1991 , 18 , 125. (27) Chen, H.; Xie, K. Energy Sources 2002 , 24 , 575. (28) Gannon, R. E.; Krukonis, V. J.; Schoenberg, T. Ind. Eng. Chem. Prod. Res. Dev. 1970 , 9 , 343. (29) Pine, S. H. Organic Chemistry; McGraw-Hill: New York, 1987; p 501, 537, and 557.

’

1758


Chemical Reviews

(66) Graves, R. D.; Kawa, W.; Lewis, P. S. Prepr. Pap. Am. Chem. Soc., Div. Fuel Chem. 1964 , 8 (3), 118. (67) Shuang, Y.; Wu, C.; Yen, B.; Cheng, Y. Energy Fuels 2010 , 24 , 2991. (68) Chen, L.; Meng, Y.; Shen, J.; Shu, X.; Fang, S.; Xiong, X. J. Phys. D: Appl. Phys. 2009 , 42 , 1. (69) Tian, Y.; Xie, K.; Zhu, S.; Fletcher, T. H. Energy Fuels 2001 , 15 , 1354. (70) Peuckert, C.; Mu R. Acetylene from Coal by the Hu ls ller, ̈ ̈ Plasma Process. Proceedings of the International Symposium on Plasma Chemistry , Eindhoven, Netherlands, July 5 −10, 1985. (71) Mueller, R.; Kirker, L.; Peuckert, C. Process for the Production of Acetylene and Synthesis or Reduction Gas from Coal in an Electric Arc Process. U.S. Patent 4,588,850, May 13, 1986. (72) Yan, B.; Cheng, Y.; Jin, Y.; Guo, C. Y. Fuel Process. Technol. 2012 , 100 , 1. (73) Cheng, Y.; Chen, J. Q.; Ding, Y. L.; Xiong, X. Y.; Jin, Y. Can. J. Chem. Eng. 2008 , 86 , 413. (74) Brachold, H.; Peuckert, C.; Regner, H. Chem. Ing. Tech. 1993 , 65 , 293. (75) Li, M.; Fan, Y.; Dai, B.; Deng, W.; Liu, X. Thin Solid Films 2001 , 390 , 170. (76) Keusenkothen, P. F.; Hershkowitz, F. Conversion of Co-fed Methane and Low Hydrogen Content Feedstocks to Acetylene. U.S. Patent Application 2010/0130803A1, May 27, 2010. (77) Gannon, R. E.; Krukonis, V. J.; Schoenberg, T. Prepr. Pap. Am. Chem. Soc., Div. Fuel Chem. 1969 , 13 (4), 321. (78) Joseph, R. T. Prepr. Pap. Am. Chem. Soc., Div. Fuel Chem. 1964 , 8 (3), 50. (79) Howard, W. B.; Wood, B. H.; Kaltenbacher, E. J. Chem. Eng. Prog. 1961 , 51 , 50. (80) Wang, B.; Tian, Y.; Zhang, Y.; Zhu, S.; Lu, Y.; Zhang, Y.; Xie, K. Energy Sources A 2007 , 13 , 1195. (81) Patrick, A. J.; Bentley, G. K.; Kaleel, M. K. Altern. Energy Sources 1980 , 6 , 65. (82) Grangier, L.; Gibson, J. Coal Utilisation: Technology, Economics and Policy; Graham and Trotman: London, 1981; pp 278 and 385. (83) Bozzuto, C. T. Acetylene from Coal and an Electric Arc. U.S. Patent 4,487,683, December 11, 1984. (84) Sharkey, A. G.; Shultz, J. L.; Friedel, R. A. In: Coal Science; Given, P. H., Ed.; American Chemical Society: Washington, DC, 1966; Chapt. 40. (85) Karn, F. S.; Sharkey, A. G. Prepr. Pap. Am. Chem. Soc., Div. Fuel Chem. 1966 , 10 (2), 44. (86) Gasner, L.; Denloye, A. O.; Regan, T. M. Chem. Eng. Commun. 1986 , 48 , 4. (87) Bamwenda, G.; Moore, E.; Wan, J. K. S. Res. Chem. Intermed. 1992 , 17 , 243. (88) Sprouse, K. M.; Schuman, M. D.; Combs, P. Production of Acetylene from Coal by Contact with a Combustion Gas. U.S. Patent 4,536,607, August 20, 1985. (89) Gannon, R. E.; Manyik, R. M.; Dietz, C. M.; Sargent, H. B.; Thribolet, R. O.; Scha ff er, R. P. Acetylene. In Kirk-Othmer Encyclopedia of Chemical Technology; Wiley: New York, 2004; p 177. (90) Nieuwland, J. A.; Vogt, R. R. The Chemistry of Acetylene; Reinhold: New York, 1945. (91) Chenier, P. J. Survey of Industrial Chemistry ; VCH: New York, 1992; pp 138, 175, and 267. (92) Davis, H. G.; Keister, R. G. In Industrial and Laboratory Pyrolyses; Albright, L. F., Crynes, B. L., Eds.; American Chemical Society: Washington, DC, 1976; Chapt. 22. (93) Alexander, S. R. Substitute Coal from Acetylene Production Byproducts. U.S. Patent 5,104,417, April 14, 1992. (94) McMurry, J. Organic Chemistry; Brooks/Cole: Paci�c Grove, CA, 2000; p 275. (95) Fey, M. G. Arc Heater Apparatus for Producing Acetylene from Heavy Hydrocarbons. U.S. Patent 4,105,888, August 8, 1978.

Review

(96) Katz, M.; Carluccio, F.; Mallari, G.; FitzPatrick, K.; Desai, A.; Casciano, R.; Tsai, J. Production of Acetylene. U.S. Patent 4,367,363, January 4, 1983. (97) Neary, R. M. In Handbook of Industrial Chemistry; Kent, J. A., Ed.; Van Nostrand Reinhold: New York, 1974; p 533. (98) Hanford, W. E.; Fuller, D. L. Ind. Eng. Chem. 1948 , 40 , 1171. (99) Fine, L. G. Chemistry; Appleton Century Crofts: New York, 1972; p 660. (100) Roberts, J. D.; Caserio, M. C. Organic Chemistry; W.A. Benjamin: New York, 1964; p 215. (101) Roscoe, H. E.; Schorlemmer, C. A Treatise on Chemistry; Macmillan: London, 1911; p 888. (102) Hilden, D. L.; Stebar, R. F. Energy Res. 1979 , 3 , 59. (103) O Lenick, T.; O Lenick, K. Reppe chemistry. http://www. surfatech.com/pdfs/Reppe_chemistry.pdf , 2008 (104) Rush, J. K. Amateur Work Mag. 1905 , 5 , 231. (105) Ju H.; Ko G.; Peters, W. Comparison of di ff erent ntgen, lling, ̈ ̈ routes from coal to chemicals and gasoline. Proceedings of 11th World Petroleum Congress , London, Aug. 28−Sept. 2, 1983. (106) Fieser, L. F.; Fieser, M. Advanced Organic Chemistry; Reinhold: New York, 1961; pp 213 and 232. (107) Szmant, H. H. Organic Chemistry; Prentice-Hall: Englewood Cliff s, NJ, 1957; pp 112, 152, 241, and 324. (108) Reppe, W. Justus Liebigs Ann. Chem. 1956 , 601 , 81. (109) Stokes, R. G. Opting for Oil; Cambridge University Press: Cambridge, U.K., 1994; pp 35, 37, and 50. (110) Nieuwland, J. A. Ind. Eng. Chem. 1935 , 27 , 850. (111) Brewster, R. Q. Organic Chemistry. Prentice-Hall: Englewood Cliff s, NJ, 1953; pp 85, 127, 147, 170, 185, 209, 350, and 785. (112) Brown, R. F. Organic Chemistry; Wadsworth: Belmont, CA, 1975; p 353. (113) Nieuwland, J. A. Some Reactions of Acetylene; University of Notre Dame Press: South Bend, IN, 1904. (114) Kutscheroff, M. Ber. Dtsch. Chem. Ges. 1881 , 14 , 1540. (115) Othmer, D. F.; Kon, K.; Igarashi, T. Ind. Eng. Chem. 1956 , 48 , 1258. (116) Fuson, R. C. Advanced Organic Chemistry; Wiley: New York, 1950; pp 55, 74, and 384. (117) Ray, F. E. Organic Chemistry; Lippincott: Chicago, 1947; p 52. (118) Carey, F. A. Organic Chemistry; McGraw-Hill: New York, 1987; p 348. (119) Chauvel, A.; Lefebvre, G. Petrochemical Processes. 2. Major Oxygenated, Chlorinated and Nitrated Derivatives; E d́ itions Technip: Paris, 1989; pp 66, 142, 154, and 198. (120) Reppe, W. Justus Liebigs Ann. Chem. 1953 , 582 , 1. (121) Falbe, J. J. Organomet. Chem. 1975 , 94 , 213. (122) Bordwell, F. G. Organic Chemistry; Macmillan: New York, 1963; pp 300, 308, 773, and 857. (123) Hill, W. H. In Chemistry of Coal Utilization; Lowry, H. H., Ed.; Wiley: New York, 1945; Chapt. 27. (124) Jackson, W. R.; Lovel, C. G. Aust. J. Chem. 1983 , 36 , 1975. (125) Cochin, M. D. Pop. Sci. Mon. 1884 , 25 , 202. (126) Vollhardt, K. P. C. Organic Chemistry ; Freeman: New York, 1987; pp 534 and 545. (127) Timmons, R. B.; He, Y.; Jang, W. L. Zeolite Catalyzed Conversion of Acetylene. U.S. Patent 5,118,893, June 2, 1992. (128) White, N.,; Kagi, D. A.; Greer, J. G.; Tsai, P. Aromatization of Acetylene. U.S. Patent 4,424,401, January 3, 1984. (129) Reppe, W.; Schweckendiek, W.J.. Justus Liebigs Ann. Chem. 1948 , 560 , 104. (130) Collins, D. E.; Richey, F. A. In Handbook of Industrial Chemistry; Kent, J. A., Ed.; Van Nostrand Reinhold: New York, 1992; p 808. (131) Morris, P. Process technology in the Third Reich: The case of IG Farben and Buna. Oxford History of Chemistry Seminar, May 28, 2009; www.history.ox.ac.uk/hsmt/histchem/histchem_poster.pdf. (132) Taylor, R. In Introduction to Carbon Technologies; Marsh, H., Heintz, E., Rodríguez-Reinoso, F., Eds.; Universidad de Alicante: Alicante, Spain, 1997; Chapt. 4. ’

1759

’


Chemical Reviews

(133) Donnet, J. B.; Bansal, R. C.; Wang, M. J. Carbon Black ; Taylor and Francis: Boca Raton, FL, 1993; pp 61 and 91. (134) Marsh, H.; Rodríguez-Reinoso, F. Activated Carbon; Elsevier: Amsterdam, 2006; pp 47 and 471. (135) Bolouri, K. S.; Amouroux, J. Plasma Chem. Plasma Process. 1986 , 6 , 335. (136) Cooper, J. F. In Recent Trends in Fuel Cell Science and Technology; Basu, S., Ed.; Anamaya Publishers: New Delhi, 2007; Chapt. 10. (137) Bao, W.; Cao, Q.; Lu ,̈ Y.; Chang, L. Energy Sources A 2008 , 30 , 734. (138) Wagman, D. D.; Kilpatrick, J. E.; Pitzer, K. S.; Rossini, F. D. J. Res. Natl. Bur. Stand. 1945 , 35 , 468. (139) Mu H.; Deller, K.; Vollheim, G.; Ku hn, W. Chem. Ing. Tech. ller, ̈ ̈ 1987 , 59 , 645. (140) O Boyle, C. J. Ind. Eng. Chem. 1950 , 42 , 1705. (141) Moses, J. M.; Weiss, A. H.; Matusek, K.; Guczi, L. J. Catal. 1984 , 86 , 417. (142) Chen, M. H.; Chu, W.; Dai, X. Y.; Zhang, X. W. Catal. Today 2004 , 89 , 201. (143) Al-Ammar, A. S.; Webb, G. J. Chem. Soc., Faraday Trans. 1 1978 , 74 , 195. (144) Zhang, Q.; Li, J.; Liu, X.; Zhu, Q. Appl. Catal., A 2000 , 197 , 221. (145) Battison, G. C.; Dalloro, L.; Tauszik, G. R. Appl. Catal. 1982 , 2 , 1. (146) Al-Ammar, A. S.; Webb, G. J. Chem. Soc., Faraday Trans. 1 1978 , 74 , 657. (147) Ke ̧pin L.; Wołcyrz, M. Appl. Catal. 1991 , 73 , 173. ski, ́ (148) Bazzazzadegan, H.; Kazemeini, M.; Rashidi, A. M. Appl. Catal., A 2011 , 399 , 184. (149) Azizi, Y.; Petit, C.; Pitchon, V. J. Catal. 2008 , 256 , 338. (150) Chekulaeva, I. A.; Kondrateva, K. V. Russ. Chem. Rev. 1965 , 34 , 669. (151) Fieser, L. F.; Fieser, M. Topics in Organic Chemistry ; Reinhold: New York, 1963; p 349. (152) Walsh, R.; Wells, J. M. Int. J. Chem. Kinet. 1975 , 7 , 319. (153) Hyman, J.; Freireich, E.; Lidov, R. E. Dienic Hydrocarbons and Derivatives Thereof. U.S. Patent 2,875,256, February 24, 1959. (154) Suld, G.; Schneider, A.; Myers, H. K. Catalytic Dimerization of Norbornadiene to Binor-S. U.S. Patent 4,031,150, June 21, 1977. (155) Anderson, W. S. Method of Generating Combustion Gases Utilizing Polynorbornene-based Combustible Compositions. U.S. Patent 4,420,931, December 20, 1983. (156) Frey, F. E. Process for Producing Cyclopentadiene. U.S. Patent 2,434,403, January 13, 1948. (157) Morrell, C. E.; West�eld, H. W.; Scheeline, L. P.; Carlson, C. S.; Heineman, H. J. Process of Producing Cycloalkadiene from Petroleum Oils. U.S. Patent 2,511,936, June 20, 1950. (158) Chien, J. C. W., 1984. Polyacetylene: Chemistry, Physics, and Material Science; Academic Press: Orlando, FL, 1984. (159) Klavetter, F. L.; Grubbs, R. H. J. Am. Chem. Soc. 1988 , 110 , 7807. (160) Reppe, W.; Schlichting, O.; Klager, K.; To T. Justus Liebigs pel, ̈ Ann. Chem. 1948 , 560 , 1. (161) Luttinger, L. B. J. Org. Chem. 1962 , 27 , 1591. (162) Luttinger, L. B.; Colthup, E. C. J. Org. Chem. 1962 , 27 , 3752. (163) Baughman, R. H.; Bre J. L.; Chance, R. R.; Elsenbaumer, R. das, ́ L.; Shacklette, L. W. Chem. Rev. 1982 , 82 , 209. (164) Ito, T.; Shirakawa, H.; Ikeda, S. J. Polym. Sci., Polym. Chem. 1974 , 12 , 11. (165) Daniels, W. E. J. Org. Chem. 1964 , 29 , 2936. (166) Tolbert, L. M. Acc. Chem. Res. 1992 , 25 , 561. (167) Akagi, K.; Suezaki, M.; Shirakawa, H.; Kyotani, H.; Shimomura, M.; Tanabe, Y. Synth. Met. 1989 , 28 , D1. (168) Etemad, S.; Heeger, A. J.; MacDiarmid, A. G. Annu. Rev. Phys. Chem. 1982 , 33 , 443. (169) Basescu, N.; Liu, Z. X.; Moses, D.; Heeger, A. J.; Naarmann, H.; Theophilou, N. Nature 1987 , 327 , 403.

Review

(170) Lugli, G.; Pedretti, U.; Perego, G. J. Polym. Sci., Polym. Lett. 1985 , 23 , 129.

(171) Naarmann, H. Synth. Met. 1987 , 17 , 223. (172) Naarmann, H.; Theophilou, N. Synth. Met. 1987 , 22 , 1. (173) Haberkorn, H.; Heckmann, W.; Ko hler, G.; Naarmann, H.; ̈ Schlag, J.; Simak, P.; Theophilou, N.; Voelkel, R. Eur. Polym. J. 1988 , 24 , 497. (174) Cowan, D. O.; Wiygul, F. A. Chem. Eng. News 1986 , 64 (29), 28. (175) Zoss, A. O.; Hanford, W. E.; Schildknecht, C. E. Ind. Eng. Chem. 1949 , 41 , 73. (176) Goldfarb, I. J.; Sikka, S. Properties of Blends of Polyphenylsulfone and Acetylene Terminated Reactive Plasticizers. Report AFWAL-TR-81-4100, Air Force Wright Aeronautical Laboratories, Air Force Systems Command, Wright-Patterson Air Force Base, Ohio, 1981. (177) Wei, X.; Shi, H.; Qian, W.; Luo, G.; Jin, Y.; Wei, F. Ind. Eng. Chem. Res. 2009 , 48 , 128. (178) Mitchenko, S. A.; Krasnyakova, T. V.; Zhikharev, I. V. Theor. Exp. Chem. 2008 , 44 , 316. (179) Speight, J. G. Handbook of Industrial Hydrocarbon Processes ; Gulf Professional Publishing: Houston, TX, 2010; p 457.

’

1760


Production of Acetylene and Acetylene-based Chemicals From Coal

Recommend Documents