Working principle of DCS reactors and conversion rate issues

Disproportionation catalysts: Catalysts are an important component of the disproportionation process. Research on disproportionation catalysts has a long history in the United States, but the various results obtained have various shortcomings when it comes to industrial application. For example, starting in the 1950s, UCC successively employed: 1) nitrile catalysts, but the temperature required for the disproportionation reaction was relatively high, exceeding 150°C, which resulted in high energy consumption ； 2) Fat amine nitriles were then used as disproportionation catalysts, but since such catalysts required pretreatment with Lewis acids and presented a series of associated problems, their industrial application was abandoned. 3) Dimethylformamide was later used as a catalyst, but this catalyst degrades very easily during the reaction. 4) Tertiary amines composed of hydrocarbon groups with 1-2 carbon atoms are used as catalysts, but this approach also presents the problem of high reaction temperatures, exceeding 150°C. Moreover, although the calculated one-way equilibrium conversion at 150°C is relatively high (theoretically up to 18%), the actual conversion in operation is lower, around 10%. Therefore, to achieve the desired output, larger-scale facilities are necessary. 5) By the late 1970s, UCC adopted a series of amino-based commercial resins from Romonhas Corporation as disproportionation catalysts, such as the macroporous tertiary amine ion-exchange resin A-21, the macroporous quaternary amine ion-exchange resin A-26, and the gel-type quaternary amine ion-exchange resin IRA-400. This allowed the disproportionation temperature and pressure to be reduced, but the issue of low one-way conversion rate persisted. The material needs to undergo multiple cycles of heating (to increase the disproportionation conversion rate) and condensation (to separate silane, trichlorosilane, dichlorodihydrosilane, and silicon tetrachloride), which results in certain energy consumption; yet industrial application has still been achieved. Meanwhile, other companies in the United States, as well as scholars from France, Germany, Japan, and South Korea, have also carried out extensive research and achieved a series of findings, including studies on the activity of organic compounds such as N-methyl-2-pyrrolidone, methylimide, tetramethylurea, tetramethylguanidine, trimethylsilylimidazole, benzothiazole, and N,N-dimethylethylamide as disproportionation catalysts. However, since these catalysts are originally solid and turn into a powdery substance upon contact with the chlorosilane mixture, they are difficult to separate from the products of disproportionation, which limits their use in industrial production.

The issue is serious; continuing to monitor!

Although it has not been used, this reaction is a disproportionation reaction, and its mechanism is that of a disproportionation reaction. The conversion rate depends greatly on the choice of catalyst; it is said that some companies can achieve a DCS conversion rate of 95%, but it is unclear whether this is true

A resin with amino functional groups is used as a catalyst, and during the reaction, the reactor temperature and feed ratio are primarily controlled. The understanding is quite superficial; I look forward to in-depth discussions!

Recently, this blog has contributed to the discussion on this issue. http://blog.sina.com.cn/s/blog_62222ce00100ubx1.html

The anionic resin provides an amine-based environment that acts as a catalyst, enabling the continuous distillation and separation of TCS; as a result, the reaction proceeds in a reverse disproportionation direction, **increasing the conversion rate of DCS.