Study On The Direct Synthesis Of Trialkoxysilane

Trialkoxysilanes, 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 addition, copolymerization, copolycondensation and disproportionation reaction with other organic compounds, and a number of very useful substance being obtained. These in turn are used as starting materials for silane coupling reagent, coating materials or for obtaining monosilanes in high purity for semiconductor applications.In industry, trialkoxysilanes are prepared by tricholorosilane and alcohol , however, hydrochloric acid which corrode reactor, pollute environment ,is formed and the yield of trialkoxysilane is low. The process for the direct synthesis of trialkoxysilane by reacting silicon metal with an alcohol over a copper catalyst is simple, handle easily, have no environmental pollution. Now there are a few factory that can synthesize trimethoxysilane by this process at home and abroad.This dissertation reports the synthesis of trialkoxysilane by the reaction of metallic silicon with methanol or ethanol using copper(l)chloride as the catalyst. The influence of reaction conditions such as temperature, solvent, speed of feeding and catalyst are studied. And the optimum conditions for synthesizing trialkoxysilane are established. For the first time, we find the activities of the Si-Cu2Cl2 mixture pretreated by microwave prior to feeding methanol increase greatly, and the Si-Cu2Cl2 is characterized by the technique of SEM and XRD in order to study the reason of the activity of reaction effected by microwave. The condition of pretreatment which influences the reaction such as microwave power, pretreatment time and the way are discussed. The experimental results show that the activity increase greatly after the mixture(mSi:mCuC1=10:0.4) is pretreated by microwave for 3min at high fire. In the distillate, the content of trimethoxysilane is 44.2%, the content of methanol is 44.7%; after adding Cu2O, the effect is remarkable, thecontent of Trimethoxysilane is 54.2%, the content of methanol is 34.6%Trimethoxysilane is synthesized by a new process of multiple reactor , the content of trimethoxysilane is 72.3%, the content of methanol is 10.8%. Content of methanol is decreased, and make the work of separation and purification simplely. In direct synthesis of triethoxysilane , the content of triethoxysilane is 68.8% ,the content of ethanol is 17.0%. At last, the application of trimethoxysilane is investigated...