Contact Mass in the Direct Synthesis of Alkoxysilanes. Raman Spectroscopy Study

Abstract

Raman spectroscopy was used to study the composition of contact masses (CMs) CuCl + Si obtained by different methods, which are utilized in the direct synthesis of alkoxysilanes. The CMs prepared by the classical method were shown to include copper oxides in a mixture with silicon and on the surface of metallic copper and Cu5Si intermetallide. Along with copper oxides, an active phase containing terminal Cu–Cl groups was also observed. In the case of mechanochemical synthesis, the formation of copper oxides was not observed. In view of the metallic conductivity of Cu3Si and Cu5Si, their direct identification using Raman spectra is not possible. All the mentioned copper-containing phases are involved in the reaction with alcohols and esters as catalysts. A difference between the two methods for obtaining CMs comes down to the presence or absence of a "catalytic cocktail", which significantly affects the parameters of the direct synthesis course.