Study On The Co-hydrogenation Of Silicon Tetrachloride And Silicon To Produce Trichlorosilane

Disposing of SiCl₄ properly is an urgent problem for increasing the demestic polysilicon production capacity, realizing sustainable development for the PV industry. The co-hydrogenation of silicon tetrachloride and silicon to produce trichlorosilane is an effective way to depose and realise cyclic utilization of SiCl₄.The thermodynamic analysis of the co-hydrogenation of silicon tetrachloride and silicon to produce trichlosilane was calculated based on the principle of Gibbs free energy minimization. Chemical reaction equilibrium in this system was computed, the main products in this system were HSiCl₃ (TCS), H₂SiCl₂ (DCS), HCl, three independent reactions were confirmed. The Diagrams of△_rH_m^θ,△_rG_m^θand K_p^θfor the three independent reactions in this system versus temperature were plotted, the diagrams of equilibrium conversion of SiCl₄ and equilibrium yields of SiHCl₃, SiH₂Cl₂, HCl versus temperature and pressure were plotted under the conditons of temperature range 673～923K, pressure range 1²0atm, H₂/SiCl₄ molar ratio range 1～5. The results showed that low temperature, high pressure and moderate H₂/SiCl₄ molar ration were favorable for producing SiHCl₃ in this reaction.The effect of temperature, pressure, H₂/SiCl₄ molar ration and metal catalyst on this experiment were tested through experiment. The temperature range was 673～973K, pressure range was 1～20atm, H₂/SiCl₄ molar ration range was 1～5. The experiment results showed that high temperature was benefit for increasing the conversion of SiCl₄ and the yield of SiHCl₃; High pressure and moderate H₂/SiCl₄ were flavorable for increasing the conversion of SiCl₄ and the yield of SiHCl₃; Cu powder had a better catalyst effect for producing SiHCl₃ than Ni, Fe, Ti powder.