Conversion of Carbonaceous Organic Impurities (Methyldichlorosilane) in Trichlorosilane Using Weakly Basic Anion-Exchange Resin as Solid Catalyst

Abstract

Trichlorosilane (SiHCl3) is an important raw material for preparing solar cells and semiconductor chips in the Siemens method. Since the boiling points of SiHCl3 and methyldichlorosilane (CH3SiHCl2) are close to each other, it is difficult to remove CH3SiHCl2 from the raw material to obtain high-purity products by traditional distillation methods. Therefore, we propose an efficient catalytic approach to convert CH3SiHCl2 to methyltrichlorosilane (CH3SiCl3) with an anion-exchange resin as the catalyst and tetrachlorosilane (SiCl4) as the Cl donor in a continuous-flow fixed bed reactor. Seven anion-exchange resins, including D201, D301, D303, 201 × 7, D301F, D315 and D380 were evaluated. The results showed that D301 resin had the best performance. Reaction conditions such as reaction temperature, reactant molar ratio and catalyst stability were investigated. The maximum conversion of CH3SiHCl2 was 60% at an optimum reaction temperature of 150 °C, n(CH3SiHCl2):n(SiCl4) = 1:3 and a liquid hourly space velocity (LHSV) of 3.0 h−1. A possible reaction mechanism is explained based on the reaction data obtained in the current work.