Production of Methyl Ethyl Ketone From Secondary Butanol

PRODUCTION OF METHYL ETHYL KETONE FROM SECONDARY BUTANOL Process flow sheet PROCESS SELECTION: I have selected the dehydrogenation process for MEK production because of following advantage. 1. In dehydrogenation hydrogen as a byproduct is obtained that can be used as a furnace fuel. 2. In dehydrogenation process, there is the feasibility of separating the MEK from the reaction products. 3. The dehydrogenation process can easily be carried out at moderate temperature and at atmospheric pressure. 4. In dehydrogenation process, 90% of MEK can easily be converted to MEK. 5. Selective oxidation process require controlled conditions so it becomes uneconomical. 6. Chromic acid and sulphuric acid in aqueous acetone is required for selective oxidation of butanol while only brass is required for dehydrogenation of butanol. 7. The dehydrogenation reaction is a single step reaction and there are negligible chances of producing byproduct while oxidation is a three step reaction. 8. From the literature survey, it can be found that the dehydrogenation process is the most economical process.

PROCESS DESCRIPTION The cold feed of secondary butyl alcohol is pumped from the storage to a steam heater and then to a vertical thermo-syphon reboiler (vaporizer) in which the alcohol is vaporized. The thermo-syphon reboiler will be heated by the reaction products discharge from the reactor and the wet alcohol vapors will be passed to a knock-out drum (separator) to remove any entrained liquid. The liquid separated will be recycled and the dry alcohol vapors will be fed to a super heater 1 where they are super heated to a temperature of 573 K. The super heated vapors are then compressed to a second super heater 2 where they are heated to a temperature of 773 K. In these super heaters, the vapors are heated with the help of flue gases at high temperature. The superheated butyl alcohol vapours are fed to the reactor at 400-500 ºC where 90% is converted on a zinc oxide_ brass catalyst to methyl ethyl ketone and hydrogen. The reaction is,

CH3CH2–CHOH–CH3 (2- butanol)

CH3CH2-CO-CH3 + H2 (methyl ethyl ketone) (hydrogen)

The reaction products are then cooled in a vaporizer where there heat is utilized to vaporize the butanol feed liquid. The cooled products gases are then condensed in a water cool partial condenser where almost 80% of the MEK and unreacted butanol is condensed and the condensate is passed to a distillation unit. The gases effluent from the partial condenser is send to the absorber to recover remaining uncondensed MEK and alcohol. In the absorber, water is used

as an absorbent which absorb MEK and alcohol and leave from the bottom of the absorber. The off gases from the absorber containing all hydrogen, negligible water, MEK and alcohol are dried and used in a plant fuel system. The liquid discharged from the absorber is sent to a liquidliquid extraction column where trichloroethane is used to extract the MEK and alcohol and the raffinate contains water is recycled back to the absorber along with the small amount of makeup water. The extract from the liquid-liquid extraction column is sent to a solvent recovery column where trichloroethane is recovered at the bottom and is recycled back to a liquid-liquid extraction column. The top product from the solvent recovery unit is sent to a distillation column along with the condensate from the partial condenser. In the distillation column, 99% pure MEK is obtained as distillate and send to a storage where as the butyl alcohol obtained as a bottom product, is recycled back and mix with a fresh feed for reprocessing.

FLOW SHEET FOR THE PRODUCTION OF METHYL ETHYL KETONE Make up water

6 169KPa 642 K 2 142KPa 373 K

11 150KPa 300 K

13' 13 121KPa 300 K 14 300 K

2-butanol feed

18 101KPa 303 K

16 17 141 KPa 308 K

P-78

Pre-heater Storage

1 145KPa 298 K

1' 144KPa 373 K

MEK Storage Separator

Vaporizer

Reactor Absorber

3 133KPa 373 K

Pump 3' 131KPa 573 K

5 353KPa 773 K

Cooler

12 101KPa 310 K

15

Distillation Column

Superheater 1 4 355KPa 583 K

Compressor

Superheater 2

10 156KPa 335 K

7 163KPa 398 K

Liq-Liq Extraction Column

9 299 K

8

Partial Condenser

Solvent Recovery Column

E-34

Separator 19