A kind of method that dichloromethane prepares vinyl chloride monomer

Abstract

The invention discloses a method for preparing a chloroethylene monomer from dichloromethane. Under the condition of existence of a catalyst with hydrogenation activity, dichloromethane and hydrogen react to prepare the chloroethylene monomer; the reaction equation is 2CH2Cl2+H2=C2H3Cl+3HCl; the mole ratio of hydrogen to dichloromethane is (0.01-20) to 1; the reaction temperature of the reaction is 25-600 DEG C, and the reaction pressure is 0.001-10 atm. According to the method, raw materials are readily available and are low in cost, so that the production cost is low, and the reaction conversion rate is high; the chloroethylene monomer is high in selectivity; the method is a novel chloroethylene monomer synthesis technology and is suitable for being popularized and applied.

Description

technical field [0001] The invention relates to a method for preparing vinyl chloride monomer, in particular to a method for preparing vinyl chloride monomer by hydrogenation coupling reaction of dichloromethane. Background technique [0002] Vinyl chloride (CH 2 CHCl) is an important monomer used in polymer chemical industry, and is widely used in the production of polyvinyl chloride (PVC) in industry. At present, the industrial production methods of vinyl chloride monomer mainly include ethylene method and acetylene method. [0003] The acetylene method uses acetylene as a raw material, under the action of a mercury catalyst (mercury chloride loaded on activated carbon), reacts with hydrogen chloride to synthesize vinyl chloride monomer, and the vinyl chloride monomer is polymerized into PVC. The process is simple, the conversion rate of acetylene is more than 98%, and the selectivity of vinyl chloride is more than 99%. It is the earliest PVC production method to achieve...

AI Technical Summary

Problems solved by technology

In the vinyl chloride monomer synthesis process of the ethylene method, the reaction temperature of the ethylene dichloride pyrolysis furnace is only 500-550 °C, while in the French patent FR2711649, methyl chloride and chlorine need to be reacted at a high temperature of 700-1300 °C. This will inevitably require higher corrosion resistance and high temperature tolerance of the reaction device, which will greatly increase the investment cost of the reaction device

[0032] (2) The synthesis route of vinyl chloride is less feasible

Yet, although this patent has carried out exhaustive theoretical analysis to the synthetic vinyl chloride of methyl chloride and dichloromethane, concrete embodiment is not provided

In fact, follow-up studies conducted by domestic researchers have shown that it is difficult to find a suitable catalyst that can convert methyl chloride and methylene chloride into vinyl chloride.

This shows that, at least so far, it is very difficult for the new synthesis process of vinyl chloride provided by this patent to change from theory to reality.

[0033] (3) The selectivity of vinyl chloride is low

Among all the technical routes, only the high-temperature pyrolysis route of methyl chloride and chlorine gas given by French patent FR2711649 can obtain a relatively high vinyl chloride selectivity of about 30%, but the reaction conditions of this route are harsh and there are many types of products. greatly reduces its economic viability

As for other vinyl chloride synthesis routes, the highest selectivity of vinyl chloride is only about 10%, which is basically of no practical value

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