Study On The Direct Synthesis Of Triethoxysilane

Triethoxysilane is an kind of important chemical raw materials, which is widely used in silane coupling-reagent like silicone oil, polysilane and resin production. Triethoxysilane is prepared by alcoholysis of trichlorosilane in industry, the process of which is complex,associated with a large number of hydrogen chloride gases, apparatus corrosion, pollution of the environment and low-yield. In this paper, a direct synthesis method for producing object product is discussed by reacting ethanol and silicon in the presence of a copper catalyst, and in a high-temperature stable organic solvent. This technique is simple, easy to operate and pollution-free. Therefore, deeply studying the process of the direct synthesis of triethoxysilane will undoubtedly be of great significance.In this paper, copper, self-cupric hydroxide, copper oxide, self-cuprous oxide and cuprous chloride was used separately as a catalyst for the direct synthesis of triethoxysilane, the results of which were inspected when different types and ratio of copper compounds related catalyst were used in the direct synthesis at appropriate reaction temperature to optimize the process. Electron microprobe and X-ray diffraction was used to characterize various copper compounds catalyst. Research showed that the cupric hydroxide and the copper were difficult to form active center because their surface area was relatively small and compact, so the product wasn't prepared; the copper oxide, cuprous oxide and cuprous chloride had large surface area and the surface morphology of which was rugged and similar to honeycomb, so they could be used to prepare triethoxysilane because the active center of which is easily to form, and in all of the catalysts cuprous chloride's effect was the best. The mechanism of the reaction-direct synthesis of triethoxysilane had been preliminary discussed.In this paper, the direct synthesis process for producing object product was studied systemically by reacting ethanol and silicon in the presence of a copper related catalyst, and in a high-temperature stable organic solvent. The parameters like reaction temperature, variety and dosage of the catalyst, the feeding rate and the granularity of the silicon were optimized. And it found that the silicon and cuprous chloride after pretreatment could obtain more active center-Cu3Si, this greatly shortened the induction period and improved the yield and the selectivity of the reaction. The method and the temperature of pretreatment were also studied. The yield of triethoxysilane in the optimized condition was 59.15%, while the selectivity was 91.49%. The method to separate the product was discussed finally. The n-hexane azeotrope was used to purify the triethoxysilane and a good result was got.