Bimetal chloride catalyzed hydrogenation of silicon tetrachloride in the presence of silicon

Abstract

The efficient conversion of the by-product SiCl₄ to SiHCl₃ remains a huge challenge for the Siemens process, the most popular polysilicon manufacturing process. Herein, hydrogenation of SiCl₄ in the presence of Si was investigated in a fixed-bed reactor over various transition metal chlorides and bimetal chloride catalysts. Catalytic performances of bimetal chloride were increased significantly compared to those of monometallic chloride catalysts. The conversion of SiCl₄ for Cu 10%–Ni 10% and Cu 10%–Co 10% reached 19.68% and 20.96% at 500 °C, respectively, when the molar ratio of H₂/SiCl₄ was 4 : 1 and the H₂ volume flow was 200 mL min⁻¹. Bimetal chloride catalysts showed an obvious synergistic effect during the catalytic process. Metal chloride precursors would be transformed into the corresponding metal silicides as active phases via a solid–solid reaction. As for bimetal chloride catalysts, the presence of Co or Ni was beneficial to the dispersion of metals and the reduction of Cu. And it was favorable to the formation of more copper silicides, which is responsible for the excellent catalytic performance of bimetal chloride catalysts.