CuCl-Catalyzed Hydrogenation of Silicon Tetrachloride in the Presence of Silicon: Mechanism and Kinetic Modeling

The CuCl-catalyzed hydrogenation of silicon tetrachloride (STC) in the presence of silicon was conducted in a fixed-bed reactor. The solid mass from different reaction stages was collected and characterized using X-ray diffraction (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The characterization results were used to develop a novel reaction mechanism. This mechanism is remarkable in that the Cu–Si surface species acted as both a catalyst and a solid reactant and could be regenerated via Cu diffusion into the bulk silicon phase. Different kinetic models were formulated by employing the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) approaches. Model discrimination was used to select a kinetic model based on the E–R mechanism, in which the surface reaction between the adsorbed STC and gas-phase H2 over the Cu3Si active sites was assumed to be the rate-determining step (RDS). The kinetic parameters were estimated using nonlinear regression, and the model predictions were in good agreement with the experimental data.