Manufacturing of Chloromethane (CH3Cl)
Contents:
1. Properties
2. Manufacturing Process
3. Reactions Involved in Production of CH3Cl
4. Flow Diagram
5. Production Process
6. Applications
Properties:
|
Chemical Name |
Chloromethane, Methyl Chloride, Monochloromethane, R-40. |
|
Chemical Formula |
CH3Cl |
|
Molar Mass |
50.49 g/mol |
|
Appearance |
Colourless gas |
|
Odor |
Faint, Sweet odor |
|
Density |
1.003 g/L |
|
Melting Point |
-97.4 oC |
|
Boiling Point |
-23.8 oC |
|
Solubility in Water |
5.325 g/L |
Manufacturing Process :
Chloromethanes are produced from methane by chlorination route.
Chloromethanes namely methyl chloride (CH3Cl), methyl dichloride (CH2Cl2), Chloroform (CHCl3) and carbon tetra-chloride (CCl4) are produced by direct chlorination of CH4 in a gas phase reaction without any catalyst.
Reactions :
CH4 + Cl2 CH3Cl + HCl
CH3Cl + Cl2 CH2Cl2 + HCl
CH2Cl2 + Cl2 CHCl3 + HCl
CHCl3 + Cl2 CCl4 + HCl
The reactions are very exothermic. The feed molar ratio affects the product distribution. When CH4/Cl2 is about 1.8, then more CH3Cl is produced. On the other hand, when CH4 is chosen as a limiting reactant, more of CCl4 is produced. Therefore, depending upon the product demand, the feed ratio is adjusted.
Production Process :
Methane and Cl2 are mixed and sent to a furnace.
The furnace has a jacket or shell and tube system to accommodate feed pre-heating to desired furnace inlet temperature (about 380-300oC). To control temperature, N2 is used a diluent. Depending on the product distribution desired, the CH4/Cl2 ratio is chosen.
The product gases enter an integrated heat exchanger that receives separated CH4 (or a mixture of CH4 and N2) and gets cooled from the furnace exit temperature (400 oC).
Eventually, the mixture enters an absorber where water is used ass an absorber and water absorb the HCl to produce 32% HCl. The trace amounts of HCl in the vapour phase are removed in a neutralizer fed with NaOH.
The gas eventually is compressed and sent to a partial condenser followed with a phase separator. The phase separator produces two streams namely a liquid stream consisting of the chlorides and the unreacted CH4 and N2.
The gaseous product enters a dryer to remove H2O from the vapour stream using 98%
H2SO4 as the absorbent for water from vapour.
The chloromethanes enter a distillation sequence. The distillation sequence consist of columns that sequentially separate CH3Cl, CH2Cl2, CHCl3 and CCl4.
Applications:
The most important use of chloromethane today is as a chemical intermediate in the production of silicon polymers.
Smaller quantities are used as a solvent in the manufacturing of butyl rubber and in petrochemical industry.
Chloromethane is also employed as a methylating and chlorinating agent in organic chemisty.
