As a niche chemical product, silicone may be a bit strange to most people. In fact, the application range of silicone products covers all areas of our production and life: aviation, construction, electronics and electrical, textiles, automobiles, machinery, leather and papermaking, chemical and light industry, metal and paint, medicine and medical treatment, and so on. Among them, there is a monomer-dimethyldichlorosilane (M2 for short) is the most important and used monomer in the synthesis of silicone products. It is mainly used as raw material for silicone rubber, silicone resin, sealant, plastics, etc., accounting for about organic 90% of the monomer output in the silicon industry, its production technology and level are the key to determining the organic silicon industry.
At present, the mainstream process for the synthesis of M2 monomer still uses the Rocho reaction discovered by General Electric in 1941. The problem is that the reaction produces a large number of other by-products while obtaining M2. Therefore, improving the selectivity and yield of M2 has always been a hot and difficult point of long-term concern in the industry and academia. However, so far, the selectivity and yield of M2 are still not high enough, mainly due to the unsatisfactory effect of the key catalyst—Cu-based catalyst. On the other hand, the catalytic mechanism has not been clear so far, so the development of high-performance Cu-based catalysts still mainly depends on industrial experience.
A few days ago, the team of researcher Su Fabing from the Institute of Process Engineering of the Chinese Academy of Sciences and the team of Professor Gong Xueqing from East China University of Science and Technology cooperated to use submicron Cu2O crystals with specific crystal faces as the model catalytic system, using a combination of experiments and theoretical calculations at the molecular and atomic level. The catalytic mechanism of the copper catalyst in the Rocho reaction was initially revealed. They first discovered the catalyst with the highest M2 selectivity and yield by simulating the synthesis process of organosilicon monomers-Cu2O cubes with {100} crystal faces exposed, and then used theoretical calculations to reveal that the main reason for the performance improvement was the first reactant. Methyl chloride has stronger dissociative adsorption on the {100} crystal plane. This work not only reveals the catalytic mechanism of Cu-based catalysts in the Rocho reaction at the microscopic scale, but also provides a new concept of improving reaction selectivity by adjusting the exposed crystal faces of metal oxide catalysts, which is helpful for organosilicon Development and innovation of Cu-based catalysts in industry.