Dichloromethane Production Process Introduction

1. Raw Materials

Dichloromethane is primarily made from methane (CH₄) or chloromethane (CH₃Cl) and chlorine (Cl₂).

2. Production Method

Currently, the methane chlorination process (free radical chlorination reaction) is primarily used industrially:

At a certain temperature (350-450°C) and under light or catalytic conditions, methane reacts with chlorine.

The reaction gradually produces chloromethane → dichloromethane → chloroform (chloroform) → carbon tetrachloride.

Reaction Equation (Stepwise Chlorination):

CH₄ + Cl₂ → CH₃Cl + HCl

CH₃Cl + Cl₂ → CH₂Cl₂ + HCl

CH₂Cl₂ + Cl₂ → CHCl₃ + HCl

CHCl₃ + Cl₂ → CCl₄ + HCl

3. Process Flow

Chlorination Reaction: Methane and chlorine undergo a chlorination reaction in a reactor to produce a mixed methyl chloride.

Cooling and Absorption: The reaction gas is cooled, and the by-product hydrogen chloride (HCl) is absorbed and recovered.

Separation and Rectification: The mixed product enters a distillation tower, where it is fractionally separated to produce the target product, dichloromethane. Meanwhile, the by-products methyl chloride, chloroform, and carbon tetrachloride can be recovered separately.

Refining: Further distillation and purification remove impurities to produce finished dichloromethane that meets pharmaceutical or industrial grade standards.

4. Process Features

Methane is used as the raw material, which is an abundant source.

The chlorinated product can be flexibly adjusted according to demand.

By-products (chloroform and carbon tetrachloride) can be comprehensively utilized.

Reaction conditions must be strictly controlled to maximize dichloromethane yield.