Catalyzed direct reaction of methanol with silicon

Abstract

The present research involves the study of the direct reaction of methanol with silicon in the presence of copper as a catalyst. This reaction was performed in a static form system and the reacting CH3OH vapor could be brought into contact with the Si-catalyst mixture fixed as a bed in the reaction tube at reaction temperatures 250, 300 and 350 °C. The catalysts surfaces were characterized by using a number of surface analysis techniques, such as XRD, SEM, and EDX. The products of the interaction were mainly Trimethoxysilane (TrMS) and Tetramethoxysilane (TMS) and the highest percentage were 28% for TrMS and 21% for TMS. The percentage of the methoxysilanes increases when the Cu content of the mixture and the temperature increased, while the percentage of non-silicon products HCOH and CO decreases when the Cu content and temperature increased. The rate of CH3OH reaction with Si directly depends on its pressure giving rise to an apparent reaction order of unity with respect to the CH3OH reactant. Activation energies, pre-exponential factors, and ∇S# of the reaction have been estimated. A compensation effect operated in the kinetics of the CH3OH interaction with silicon as indicated by the linear relationships which existed between the values of Ea and the corresponding values of log A. The introduction of additives into the catalyst caused either promotion or inhibition.