Approach To Generating The Right Active Phase In The "Direct" Synthesis Of Trimethoxysilanes Using The Cucl-Cu2o Catalyst

The "direct" synthesis of trimethoxysilane (M3) by the reaction of Si with methanol over the Cud catalyst often generates a large amount of erosive HCl gas, causing severe environmental pollution. Thus, it calls for the development of greener and more efficient composite catalysts. In this work, to reduce the amount of CuCl, we employed three pretreatment methods to activate the contact mass of Si powder and the composite catalyst of CuCl and Cu2O. It was found that the contact mass activated by argon (Ar), hydrogen argon (H-2/Ar) and methyl chloride (CH3Cl), respectively, exhibited different catalytic performances: the highest Si conversion (34.1%) and M3 yield (24.0%) were obtained on the sample activated by CH3Cl. Notably, the M3 yield was increased 8-fold than that of the un-activated sample. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies revealed that different activation methods led to the generation of different kinds of CuxSi phases, such as Cu3Si and Cu4Si, both of which gradually transformed into Cu15Si4 during the reaction process. Pretreatment of the contact mass with CH3Cl promoted the formation of CuxSi, which contributed to the generation of more Cu15Si4 active phase, and finally to the superior catalytic performance.