“CATALYTIC CONVERTER”
A PROJECT REPORT
Submitted by: CHRISTO T JOSEPH REG NO: 13771FDAE0077
In Partial fulfillment for the award of the degree Of
DIPLOMA
IN
AUTOMOBILE ENGINEERING
July 2016
“CATALYTIC CONVERTER”
A Project report submitted for the partial fulfillment of the Diploma in automobile engineering. 2013 – 2016 By
CHRISTO T JOSEPH REG NO: 13771FDAE0077
Under the Guidance of
External Guide Dr. Ajay Kumar Head of the department Dept. of Automobile engineering College of engineering Kidangoor Kidangoor P.O, Kottayam, Kerala - 686572
GUIDE’S CERTIFICATE
I hereby certify that the research work embodied in the dissertation entitled “catalytic converter” has been under taken and completed by CHRISTO T JOSEPH under my guidance and supervision. I also certify that he has fulfilled all the requirements under the covenant governing the submission of dissertation for award of DIPLOMA IN AUTOMOBILE ENGINEERING.
Place: Pala Date: 12 July 2016
Dr. Ajay Kumar Head of the department Dept. of Automobile engineering College of Engineering Kidangoor Kottayam, Kerala
DECLARATION I hereby declare that the research work embodied in the dissertation entitled ”CATALYTIC CONVERTER” has been carried out by me, under the guidance and supervision of Dr. Ajay Kumar, head of Automobile Dept. College of engineering kidangoor. I also declare that this dissertation has not been submitted for the award of Diploma in Automobile Engineering.
Place: Pala Date: 12 July 2016 CHRISTO T JOSEPH REG NO: 13771FDAED0077
ABSTRACT Catalytic converter is most effective device which converts harmful gases due to engine exhaust into eco friendly gases. In this report, I have tried to bring into the importance of reducing air pollution and why catalytic converter is necessary in automobile. Also the principles of the catalytic converter and explains its workings. And I tried to bring in advance technology found out now a day for reducing air pollution. By best effort, I tried to focus on the necessity of subject. I hope my report is one step ahead in this direction.
CONTENTS CHAPTER
TITLE
PAGE
NO: 1
Introduction 1.1 Introduction
1
1.2 Cat-con as a pollution Control device.
1
1.2.1 Catalytic converter
1
1.3 History 1.4 position of catalytic converter 2
CONSTRUCTION 2.1 Basic components 2.2 Coating process 2.3 Detailed coating process 2.4 Catalyst materials 2.5 Types of catalytic converter 2.5.1 Three way catalytic converter 2.5.2 Ceramic Honeycomb type 2.5.3 Monolith 2.5.4 Pellet type
3
Working 3.1 conversion process 3.1.1 Pollutants released by a car engine 3.2 Ways of conversion 3.3 Fuel effects in performance of catalytic converter 3.3.1 Compression ignition direct injection 3.3.2 Unleaded petrol 3.3.3 Leaded versus unleaded
CHAPTER
TITLE
PAGE NO:
3.4 precautions 3.5 Advantages 3.6 Disadvantages 3.7 Improvements 3.7.1 Chrysler’s Catalytic Air supply system 4
New developments 4.1 Improvements in latest catalytic devices 4.1.1 Thin wall ceramic substrates 4.4.2 Electrically heated converter 4.4.3 Pre converter 4.2 Catalytic Converter troubleshooting 4.3 Reasons of catalytic converter failures 4.3.1 Clogged or poisoned cat-con 4.3.2 Bad exhaust valves 4.3.3 Out of tune engine 4.3.4 Excess fuel overheating the cat-con 4.3.5 Malfunctioning oxygen sensor 4.3.6 Oil or antifreeze entering the exhaust
5
Catalytic converter news 5.1 Direct fit catalytic converter 5.2 So-gel technology 5.3 Catalytic converter laws
6
Conclusion
7
References
CHAPTER 1 INTRODUCTION 1.1 Introduction As we know, air pollution is big challenge for the world. Air pollution is not national problem. An under developed country like India control of air pollution is very necessary. Air pollution happens due to industrial waste, automobile & by nature. But among that air pollution due to automobile contributes to 70% of total air pollution. So now a day control of automobile pollution & it’s bad effect is very necessary. We have several ways for controlling automobile pollution, but most effective way is by using catalytic converter in the automobile 1.2 Catalytic Converter as a Pollution Controller Device The catalytic converter does a great job at reducing the pollution, but it can still be improved substantially. One of its biggest shortcomings is that it only works at a fairly high temperature. When you start your car cold, the catalytic converter does almost nothing to reduce the pollution in your exhaust. 1.2.1 Catalytic converter As the name suggests, it basically converts harmful gases into harmless gases, which are environment friendly, with the help of a catalyst. Engine exhausts having harmful gases like CO, NOx & HC which are converted into harmless gases like CO2, N2 & H2O respectively with the use of catalytic converter. 1.3 History In 1973, General Motors faced new air pollution regulations and needed a way to make its cars conform to the stricter standards. Robert C. Stempel, who at the time was a special assistant to the GM president, was assigned to oversee development of a technology capable of addressing the problem. Under Stempel’s guidance, GM built on existing research to produce the first catalytic converter for use in an automobile. Catalytic converters were first installed in vehicles made in 1975 in response to EPA regulations passed two years earlier tightening auto emissions and requiring a gradual decrease in the lead content of all gasoline.
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In a study released on Nov. 28, 1973, the EPA determined “that lead from automobile vehicles was posing a direct threat to public health” Although catalytic converters were developed in the 1950s, the device couldn’t be used in vehicles because the lead in gasoline would render them useless. Since the introduction of stringent emission regulations in the US in the 1970s, car manufacturers have modified their exhaust systems to incorporate catalytic converters for the removal of Nox, CO and hydro carbons. All new cars registered throughout the European Union from 1st January 1993 have to be fitted with catalytic converters. Platinum, palladium and rhodium are the main active components. A potential problem appears with the release of platinum group metals (PGMs) from the converters into the environment. There is now convincing evidence for the release of platinum group metals (PGMs) into the environment, possibly by abrasion of the autocatalyst. As a result, PGMs are found to have increased in the environment. In recent study, we found that PGMs have increased in road dust since 1984 and particularly 1991. 1.4 Position of Catalytic Converter in an Exhaust System First, all catalytic converters were installed in under floor. This design needed further improvement. So additional starter catalyst is installed in closed coupled position. The catalytic converter usually looks like a muffler and is located underneath the vehicle in the proximity of the passenger seat in most cars although some cars have multiple converters. The purpose of a catalytic converter is to convert harmful hydrocarbons, carbon monoxide, and nitrogen oxides into harmless compounds. The catalysts inside the catalytic converter convert carbon monoxide and hydrocarbons into carbon dioxide and water, and nitrogen oxides back into nitrogen and oxygen.
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CHAPTER 2 CONSTRUCTION 2.1 Basic Components (1) Substrate: is ceramic honeycomb like structure with thousands of parallel channels that provide a large surface area for the engine exhaust. (2) Wash
Coat: A coating
that
increases
the
effective
surface
area
of
the
substrates & facilitates the application of precious metal catalyst onto the surface of the ceramic surface of the ceramic substrate. (3) Catalyst: Precious metal catalyst-the heart of catalytic converter, applied to wash coated ceramic substrate. (4) Mat: It provides thermal insulation & protects against mechanical shock & chassis vibration. (5) Can: A metal package that encase all the above components. (6) Heat Shields: They are used to protect various parts surrounding the catalytic converter, form thermal shocks. 2.2 Coating Process Catalytic converters are used in automobile and industries for pollution abatement. They usually consist of cordierite ceramic extruded to form a structure of honeycomb-like cells that extend as channels along the catalytic converter length. A paint-like liquid containing the precious metal catalyst is coated on the channel walls. During operation, exhaust gases are conveyed with low pressure drop through the catalytic converter. The pollutant gases are removed by catalytic activity in the catalyst coating. Coating processes for catalytic converters present several challenges that have been tackled in the visual analysis lab. Catalytic converter manufacturers complained that quality control of catalyst coat thicknesses is difficult. In addition the coating liquid often clogs several of the catalytic converter channels. Usually, the monoliths are sprayed with a non-viscous solution containing dissolved catalyst. Sometimes the monoliths are coated by dipping into catalyst enriched slurry and then blowing out the slurry with air. 3
The air clears the channels leaving a layer of deposited slurry solids on the channel walls. A solid coat of catalyst, called the washcoat, is left after the liquid components dries out. A third method is to suck the slurry through the monoliths by lowering one end of the monolith into catalyst slurry and applying a vacuum at the other end. 2.3 Detailed Coating Process (1) Engineers its converters with maximum airflow in mind. The large surface area of the honeycomb ceramic catalyst combines with a detailed coating process to allow the most exhaust to flow through the converter. Innovative technology allows each catalyst to both oxidize and reduce harmful emissions. (2) A ribbed body encases the ceramic to reduce expansion and distortion when the converter reaches its high operating temperature. The ribs form channels that hold the ceramic in proper alignment and protect the cushioning mat from direct exposure to exhaust gases. (3) Converters have a smooth-flowing, 1/2” lap joint where the neck and body connect. This joint prevents the neck from extending into the body, where it could impede exhaust flow. (4). Maintains separate dies for several converter body sizes and corresponding neck sizes. This process eliminates the need to adapt neck sizes to make them fit on a single converter body size, which would increase back pressure and decrease airflow and horsepower. (5) The ceramic catalysts are seam welded to a heavy-gauge, stainless steel converter body. Furthermore, a stainless steel heat shield is seam welded to the inner converter body. This style of welding forms a strong bond between the converter’s components and prevents the ceramics from shifting. (6) Ribbing on the shield offers a final layer of protection against heat damage while reinforcing the structural stability of the entire converter. 2.4 Catalyst material A catalytic is a substance that causes chemical reaction without being changed by the reaction. Noble metals are used as catalysts. A catalytic is a substance that causes chemical reaction without being changed by the reaction. Noble metals are used as catalysts. ▪ Oxidation converters: - 70% platinum & 30% palladium is not as efficient as platinum but it is used to reduce overall cost of the unit. 4
▪ Reduction converters: - it consists of platinum & rhodium. 2.5 Types of catalytic converter There are many types of structures used in catalytic converters. Honeycomb and Ceramic beads. Most cars today use a honeycomb structure. 2.5.1 Three-way Catalytic Converter In a three-way catalytic converter, the converter is positioned in front of the oxidation catalyst. A three-way catalytic converter reduces Nox emissions as well as CO and HC. The three-way catalyst reduces Nox into nitrogen and oxygen. The section of a three-way catalytic converter that breaks Nox down into harmless nitrogen and oxygen through a reduction reaction. 2.5.2 Ceramic honeycomb Structure A ceramic honeycomb structure is provided with a plurality of open passages extending there through in an axial direction thereof. The wall thickness of at least one part of the open passages formed in an annular portion along an outer peripheral surface of the structure is made larger than that of the other open passages formed in the other portion than the annular portion, and the structure has excellent mechanical strength and thermal shock strength. A method for producing a ceramic honeycomb structure comprising applying a coating material to an outer peripheral surface of the ceramic honeycomb body to form an outer peripheral wall, the thickness of the coating material applied being determined from the outer diameter of the ceramic honeycomb body and the drying shrinkage ratio of the coating material, such that the outer diameter of the dried ceramic honeycomb structure is within a target outer size ±1.4 mm. (1) The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the Nox emissions. When an No or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and hold on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are stuck to the catalyst, forming N2. For example: NO => N2 + O2 or 2NO2 => N2 + 2O2
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(2) An oxidation catalyst is a flow through exhaust device that contains a honeycomb structure covered with a layer of chemical catalyst. This layer contains small amounts of precious metal-usually platinum or palladium-that interact with and oxidize pollutants in the exhaust stream (CO and unburned HCs), thereby reducing poisonous emissions.
The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. For example: CO + O2 => 2CO2
2.5.3 Monolith Type (1) Shell: Manufactures make converter housing of shell of two stamped metal pieces welded to gather to form a round or oval assembly. (2) Monolith: It is made from ceramic matter. Honeycomb design has hundred of cellular passages for the exhaust gases to floe through. (3) Flow diffuser: It is situated between converter inlet & catalytic element. It is used to obtain uniform flow of exhaust gases over the entire area. If it is not present the pellet type gases will pass through the center of the element only. 2.5.4 Pellet Type (1) Pellet: It consists of a small aluminum oxide pellet of 1/8 to 1/10 of an inch in diameter. They are coated with thin layers of platinum or palladium. (2) Baffles: They direct the flow. First of all gases pass through the upper baffles. They have to pass through the pellets & get out through lower baffles. Baffles support & contains the bed. (3)Insulation: Situated between inner 7 outer shells. It retarded the transfer of heat so no heat shield is required here. Drain plug: It permits removal of catalysts pellets with special requirement 6
CHAPTER 3 WORKING
3.1 Conversion process Most modern cars are equipped with three-way catalytic converters. “Three-way” refers to the three regulated emission it helps to reduce carbon monoxide, VOCs and Nox molecules. The converter uses two different types of catalyst, a reduction catalyst and an oxidization catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required (they are very expensive). 3.1.1 Pollutants produced by a car engine In order to reduce emissions, modern car engines carefully control the amount of fuel they burn. They try to keep the air-to-fuel ratio very close to the stoichiometric point, which is the calculated ideal ratio of fuel. Theoretically, ratio the fuel will be burned using all of the oxygen in the air. For gasoline, the stoichiometric ratio is about 14:7:1, meaning that for each pound of gasoline, 14.7 pounds of air will be burned. Sometimes the mixture can be lean (an air-to-fuel ratio higher than 14.7), and other times the mixture can be rich (an air-to-fuel ratio lower than 14.7). The main emissions of a car engine are: (1) Nitrogen gas (N2) – Air is 78%, nitrogen gas and most of this passes right through the car engine. (2) Carbon dioxide (CO2) – This is one product of combustion. The carbon in the fuel bonds with the oxygen in the air. (3) Water vapor (H2O) – This is another product of combustion. The hydrogen in the fuel bonds with the oxygen in the air.
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These emissions are mostly benign (although carbon dioxide emissions are believed to contribute to global warming). But because the combustion process is never perfect, some smaller amounts of more harmful emissions are also produced in car engines. (1) Carbon monoxide (CO) – a poisonous gas that is colorless and odorless. (2) Hydrocarbons or volatile organic compounds (VOCs) – produced mostly from unburned fuel that evaporates. (3) Sunlight breaks these down to form oxidants, which react with oxides of nitrogen to cause ground level ozone (O3), a major component of smog. (4) Nitrogen oxides (NO and NO2, together called Nox) – contributes to smog and acid rain, and causes irritation to human mucus membranes. These are the main regulated emissions, and also the ones that catalytic converters are designed to reduce. 3.2 Ways of conversion (1) 2-way pellets (bead) type This type of converter either oxides or reduces but not both at one time, so most often not used now a days. (2) 3-ways / dual / hybrid type First of all exhaust gases passes through TWC where it reduces Nox & partly oxidizes HC/CO. Then pump provides sufficient air form oxidation Purpose. Then it passes through COC, where final oxidation of HC/CO. Then Pump provides sufficient air from oxidation purpose. Then it passes through COC, where final oxidation of HC/Co takes place. 3.3 Fuel effects in performance of catalytic converter 3.3.1 Compression ignition direct injection(CIDI) CIDI engines have highest thermal efficiency of any proven automobile power plant. Which increases fuel economy up to 35% . They are expected to deliver a fuel economy of up to 80mpg in vehicles being developed under “ partnership for a new generation of vehicles (PNGV) “ the joint venture of automobile giants like Chrysler corp., ford motor co., 8
Lawrence Livermore national lab, loss Alamos national lab, dark ridge national, and Sandia national lab. The primary technical barrier is emissions, learn burning CIDI engines have high concentrations of O2, and so reduction of Nox, is not possible with a high standard catalyst. So they have prepared a full size (110 cubic inch) converter & tested with a CIDI engine on a dynamometer. Test results have demonstrated a Nox reduction of 40% more than double the reduction realized with commercially available catalysts. 3.3.2 Unleaded Petrol Lead has been recognized as a health hazard. To reduce knocking (detonation) and as an octane improve 1 part of Tetraethyl Lead (TEL) PB] is added in 1300 parts of gasoline. About 85% of lead entering the atmosphere comes from TEL. Vehicles with catalytic converter must utilize and unleaded fuel. The lead itself plates the catalyst to form a coating that prevents the exhaust gas pollution reacting and therefore reacting with the catalyst. Manufacturers prevent the use of leaded fuel in a vehicle by the design of the filler tube leading down to the fuel tank. There is a special filler tube which has restriction placed at its opening which prevents the entry of large leaded fuel delivery nozzles at gasoline pumps. Lead gradually gets accumulated in the body, after certain level it causes a variety of heart, lungs, liver brain, etc. As an alternative to TEL as octane improver, either of the following can be added – part of Ethyl iodide (EI) – [(C2H5) 1] in 25 parts of gasoline. It causes diseases like gastro intestinal damage, liver kidney damage, and abnormality in fertility and pregnancy, mental development of children affected various skin disease, etc. 3.3.3 Leaded versus Unleaded Lead is there to enable higher octane petrol for better efficiency. Lead when burnt in engine is subjected to 2000-3000 degrees and is actually baked like a house brick which when emitted from exhaust fall to the ground within 10-12 feet ( heavier than air ). 9
These particles when tested various acids (like stomach acids) have no baked lead. Precede food, lead pipes containing drinking water. Lead is removed otherwise catalytic converter became clogged very quickly and stopped working. But unleaded petrol is much more dangerous. More than half a liter of unleaded petrol is not petrol. It is actually a brew of aromatics that replaced leads are Diethyl benzene, Mesitylene, Toluene, Xylene and Benzene. AI is declared carcinogeneous and will cause Leukemia and other cancer related illness. 3.4 Precautions If gases are too hot, by pass valve sends exhaust gases around the catalytic converter directly to the muffler (1) Failure to correct any of the conditions above will cause your new catalytic converter to fail. The warranty of your new converter does not cover damage described above. Tampering with or removing a catalytic converter from your vehicle is illegal and can result in expensive fines. (2) Use unleaded petrol only even one time leaded petrol will damage the catalytic converter permanently. (3) Consult an authorized service outlet at the earliest when, engine miss firing or runs irregularly, following cold start, A significant loss of power is noticed. (4)In the event of above symptoms, drive a car low speed without rapid acceleration. If the vehicle is continuously run with misfiring, it may cause overheating of shell, carpet etc. resulting into fire. So, don’t drive the vehicle with misfiring. 3.5 Advantages (1) It gives more power (2)It gives better performance (3) It gives reduced fuel consumption (4) Reducing amount of CO, HC and Nox, particulate emission, it leads to pollution free environment.
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(5) It is having long life. (6) It has to be replaced after 50,000 miles. Here no lead is used so no TEL is formed, which is very harmful to health. 3.6 Disadvantages (1)Cost is high. (2)Volume required is high. (3)Some amount of weight is added. (4)There is over temperature problem. (5) Shields required otherwise areas around it will be damaged. (6)Catalytic material is lost. 3.7 Improvements 3.7.1 Chrysler’s Catalytic Air supply system First of all Chrysler used its air injection system to supply the additional air to catalytic converter. Afterwards it modifies it by addition of air switching valve and coolant control engine vacuum switch. These units are control the air from the injection pump during and after engine warm up. This assists in oxidation of HC and Co. ON some 1977 and later vehicles Chrysler installed a small oxidation type converter welded into the engine exhaust pipe about 6 to 12 inches from the exhaust manifold. The device sometimes known as under hood converter begins the oxidation of HC and Co compounds before they reach the main under floor unit. This result in a more complete oxidation of harmful emission in the exhaust gas. Oxygen along with HC and Co compounds pass into the mini converter where the oxidized compounds pass into the main converter along with additional oxygen. The main converter completes the oxidation HC and Co compounds and converts them into harmless carbon dioxide and water.
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CHAPTER 4 NEW DEVELOPMENTS
4.1 Improvements in latest catalytic devices Over the years the technology behind the catalytic converters got better, there have been some significant new innovations in this technology. They are; 4.1.1 Thin wall ceramic structures They are extruded from dense, high strength ceramic substrate without sacrificing mechanical strength, total surface area remains same, back pressure reduces, conversion efficiency increases and thermal expansion reduces. 4.1.2 Electrically heated catalyst (EHC) To reduce ‘cold start’ emission in first 2 minute of operation, when most of automobile’s pollutants are emitted unconverted. Here metal monolith heats the cold exhaust gases, pre converter accelerates exhaust gas conversion and then ceramic main substrate begins conversion in less than 10 second engine ignitions. 4.1.3 Pre-converter Another option for cold start control is a small converter placed very close to the engine to accelerate exhaust gas converter. 4.2 Catalytic converter troubleshooting To understand why a catalytic converter fails, you need to know how it works. The catalytic converter is part of the automobile exhaust system. It converts harmful compounds in exhaust into harmless compounds. In a typical passenger car, the catalytic converter, which resembles a muffler in shape, is between the engine and the muffler. It’s on the underside of the car, usually underneath the passenger seat. Maybe you have felt its warmth through the floor on a long trip. Catalytic converters have been standard on U.S. automobiles since the mid-1970s. The catalytic converter helped drive the push toward unleaded gasoline as well. Leaded gasoline contaminates the catalyst used inside a catalytic converter, destroying its usefulness and leading to a clogged converter. 12
After the engine exhaust gases pass through the catalytic converter, the gases go through the muffler or mufflers, depending on the make of the automobile and rarely have a problem with being clogged or plugged during its lifetime. The inside of the catalytic converter is a honeycomb set of passageways or small ceramic beds with catalysts. A chemical reaction takes place to make the pollutants less harmful. There are many passages for the exhaust gases to flow, less allow for the maximum amount of surface area for the hot gases to pass. 4.3 Reasons of catalytic converter failures 4.3.1 Clogged or poisoned catalytic converter There really is no “inspection port” for the consumer or mechanical to see an actual clog in a converter. Often, the only way to tell if a catalytic converter is malfunctioning (plugged) is to remove it and check the change in engine performance. When a clogged converter is suspected, some mechanics temporarily remove the O2 sensor from the exhaust pipe ahead of the catalytic converter and look for a change in performance. A catalytic converter relies on receiving the proper mix of exhaust gases at the proper temperature. Any additives or malfunctions that cause the mixture or the temperature of the exhaust gases to change reduce the effectiveness and life of the catalytic converter. Leaded gasoline and the over-use of certain fuel additives can shorten the life of a catalytic converter. 4.3.2 Bad exhaust valves Sometimes you can tell that a converter is clogged because you don’t go any faster when you push the gas pedal. Also, there usually is a noticeable drop in gas mileage associated with a clogged catalytic converter. A partially clogged converter often acts like an engine governor. Limiting the actual RPMs to a fast idle. A totally clogged converter causes the engine to quit after a few minutes because of all the increased exhaust back pressure. The catalytic converter, like the rest of the emission system, typically has a warranty length that exceeds the term of the warranty for the rest of a typical U.S. automobile. 4.3.3 Out of tune engine Anytime an engine is running out of tune due to improper air/fuel mixture, misfiring cylinders, faulty engine sensors, incorrect ignitions timing, etc., damage to the catalytic converter will be incurred. Proper and regular servicing per the auto manufacturers recommendations are necessary to prevent premature catalytic converter failure. 13
4.3.4 Excess fuel overheating the catalytic converter An engine that is performing at peak efficiency will burn all the fuel in the combustion chamber during the combustion process. An engine that is not performing properly, that is not burning all the fuel, will allow unburned or excess fuel to enter the exhaust system. When this excess or unburned fuel contacts the hot core of the converter it will ignite. This constant infusion of unburned fuel will cause temperature to continuously rise above the designed operating temperature until the core of the catalytic converter will actually melt. Possible causes for the excess fuel entering the exhaust system are an incorrect fuel mixture, incorrect timing, corroded spark plugs, worn and cracked ignition wires, improper fuel pressure, a faulty oxygen sensor, sticking float, faulty fuel injector or a malfunctioning check valve. 4.3.5 Malfunctioning oxygen sensor The oxygen sensor measures the amount of oxygen present in the exhaust gas. Depending on the voltage generated by the oxygen sensor, the engine management system will change the air/fuel ratio to obtain the desired oxygen level present in the exhaust gas. A malfunctioning oxygen sensor sending an erroneous reading to the engine control system can causes a too rich or too lean condition. A rich condition will cause a converter to overheat and melt down from the unburned fuel being ignited while a lean condition can result in a misfire that can lead to the same result. Oxygen sensors were out and need to be changed per your auto manufacturer’s time and mileage limits. 4.3.6 Oil or antifreeze entering the exhaust When oil or antifreeze enters the exhaust system and contacts the hot core of the converter the oil and antifreeze will burn off leaving carbon deposits. The carbon deposits will coat the core of the converter thus reducing the catalytic converter’s ability to convert from harmful emission into harmless compounds. As the carbon deposits continue to accumulate, the pores in the ceramic catalyst will become restricted and block exhaust flow through the exhaust system. The resulting increased backpressure will result is a loss of power and overheated engine components. Possible causes are worn piston rings, faulty valve seals or valve guides, blown head gasket or intake gaskets, or warped engine components.
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CHAPTER 5 CATALYTIC CONVERTER NEWS
5.1 Direct fit catalytic converter The purpose of the emission control system is just that; it controls the emissions and exhaust from your vehicle. The idea is to turn the harmful gases your car manufactures into harmless ones that don’t ruin the environment, or us. Some of the problem gases are: hydrocarbons (unburned), carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, phosphorus lead and other metals. To prevent the engine from polluting the environment with these gases, we include a catalytic converter in our emission system. The catalytic converter is installed in the exhaust line, between the exhaust manifold and the muffler, and makes use of chemicals that act as a catalyst. Basically, the harmful gases enter the catalytic converter, a kind of stainless steel container. The converter is lined with chemicals such as aluminum oxide, platinum and palladium. These chemicals cause the carbon monoxide and hydrocarbons to change into water vapor and carbon dioxide. Some converters have a third lining of chemicals, platinum and rhodium, that reduce nitrogen oxides (three-way, dual bed catalytic converter). The reason that leaded gas cannot be used in an engine with a catalytic converter is that the lead coat the chemicals in the chemical lining cant’s come in contact with the pollutants. 5.2 So-Gel technology A new application of a chemical process called sol-gel technology shows promise for making automobile catalytic converters dramatically more efficient in reducing harmful air pollution emissions by targeting the first minute-and-a-half in which the car is running after a cold start, according to research presented at a meeting of the American Chemical Society. Most catalytic converters turn harmful combustion products such as hydrocarbons, carbon monoxide, and nitrogen oxides into benign water, carbon dioxide, and nitrogen. But during the first 90 seconds, while the catalytic converter has not reached optimum operating condition and maximum conversion efficiency, up to 70 percent of the total air pollutants discharged during a normal driving cycle are exhausted to the atmosphere.
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This brief window of pollution emission has been targeted as the point of attack by Chaitanya Narula and his colleagues in the chemistry department of the Ford Motor Company Research Laboratory in Dearborn, MI, to meet upcoming goals for ultra low automobile emissions. 5.3 catalytic converter laws In 1986, the U.S. Environmental Protection Agency issued new guidelines for the construction, efficiency and installation of aftermarket catalytic converters. All CleanAir converters listed in this catalog have been designed, tested and manufactured to meet this policy. In addition, CleanAir converter listed in this catalog is appropriate for use under the current requirements of the California Air Resources Board (C.A.R.B.). E.P.A. guidelines state that replacement converters may be installed only in the following situations: (1) The vehicle is missing a converter (2) A state or local inspection program has determined that the existing converter need replacement. (3) Vehicles manufactured prior to 1996 must have more than 50,000 miles, and a legitimate need for replacement must be established and documented. (4) In cases of OBD Il-equipped vehicles (1996 and later), the O.E. manufacturer's year/80,000-mile warranty must have expired and a legitimate need for (5) Replacement must have expired and a legitimate need for replacement must be established and documented.
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