Study On The Preparation Process Of Direct Synthesis Of Triethoxysilane

Triethoxysilane is an important alkoxysilane and silicone intermediates, and is one of the basic raw materials on the preparation of silicon materials. Triethoxysilane, composed of a silicon atom to which three alkoxy groups and a hydrogen atom are bonded, are very reactive and unstable. They therefore undergo numerous reactions, such as copolymerization, copolycondensation and disproportionation reaction with other organic compounds, and a number of very useful substances being obtained. The direct synthesis triethoxysilane is the reaction that silicon and ethanol used as materials, copper used as catalyst and as the presence of organic solvent. Compared with traditional alcoholysis process, the direct synthesis process had obvious advantages in the aspect of technique steps, resources availability, environment effects and industrial structure. Now there are a few factories that can synthesize triethoxysilane by this process at home and abroad.In this paper, cuprous chloride, cuprous oxide and copper oxide are used separately as a catalyst for the direct synthesis of triethoxysilane. Scanning electron microscope and X-ray powder diffraction are used to characterize various copper compounds catalyst. Nanometer composite catalyst is inspected on the effect of reaction, and the better ratio of the catalyst is chosen. The experiment shows the yield and selectivity attain to 83.2% and 95.1% separately, when m(CuCl): m(Cu₂O): m(CuO)=5:3:3. Effective amount of catalyst is 5% by weight of the silicone metal. The reaction temperature is 210°C. Particle size of silicone is 200-320 meshes. Ethanol is fed into the slurry with the feed rate of 1.5ml/min and the amount of ethanol is 6 times by weight of the silicone metal. Suitable ratio of solvent to metallic silicon is 4.0-6.0 mL/g Si. The selectivity for triethoxysilane is close to 99% with 90% conversion of silicon. Simple distillation and reactive distillation are also studied to inspect the effect of separating and purifying the product. The mechanism of the reaction-direct synthesis of triethoxysilane has been preliminary discussed. It is approved that Cu3Si is the basis of the direct synthesis, which consistented with the mechanism of liquid-solid reaction.