Method for producing cyclosiloxane through solvent oil catalytic cracking

Abstract

The invention discloses a method for producing cyclosiloxane through solvent oil catalytic cracking. The method comprises the following steps: vacuumizing a cracking kettle until the pressure in the kettle is -0.099 to -0.095 MPa, slowing heating the cracking kettle to a temperature of 120 DEG C; adding a certain amount of solvent oil into the cracking kettle; then adding a certain amount of hydrolysate and a KOH solution into the cracking kettle; heating the cracking kettle until the temperature in the cracking kettle reaches 130 to 150 DEG C to trigger the cracking reaction; stopping exchanging solvent oil after the cracking reactions have been carried out for a while, and keeping on carrying out cracking reactions. The method has the following advantages: solvent oil is taken as the catalyst, thus the heat transfer is uniform, the local overheating phenomenon is eliminated, the reaction speed is accelerated, and the cyclosiloxane yield is increased; the alkali catalyst using amount is reduced, and safety hazard is reduced; moreover, the device amplification is easy, the energy consumption and pollution is reduced, and the cracking technology is effectively improved.

Description

technical field [0001] The invention relates to the field of siloxane production, in particular to a method for producing cyclic siloxane mainly composed of octamethylcyclotetrasiloxane by catalytic cracking of solvent oil. Background technique [0002] Octamethylcyclotetrasiloxane (D4 for short), colorless transparent or milky white liquid, flammable, no peculiar smell, is a kind of hydrolyzate obtained through hydrolysis process with dimethyldichlorosilane monomer as the main raw material Based on the separation and rectification, or after the hydrolyzate undergoes cracking and rearrangement and then separated and rectified, it is a compound with a separate definition. The structural formula is: [0003] [0004] The primary form of dimethylcyclosiloxane is mainly used for ring-opening polymerization to form silicone oil, silicone rubber and silicone resin with different degrees of polymerization. These polymers are further processed into products that are widely used ...

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Problems solved by technology

[0005] The current dry cracking process used in the organic silicon monomer hydrolyzate cracking unit is highly dangerous, and potassium hydroxide is used as the catalyst for the cracking reaction, which has problems such as high labor intensity for slag discharge and difficult water consumption for slag discharge.

In the traditional octamethylcyclotetrasiloxane production process, the viscosity of the alkali catalyst reaction system is high, resulting in uneven heat transfer, so it is impossible to rearrange the long-chain linear hydrolyzate that occurs during the cracking process. The ring body affects the overall yield of the ring body product. The highest yield of the ring body in the traditional cracking process is 96%, and the yield cannot be improved.

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