Exploration of photocatalytic chlorination combined simplified distillation to produce electronic grade high-purity trichlorosilane via microchannel reactor experiments, multiphase-flow simulation, ReaxFF MD, and DFT

High-purity trichlorosilane (SiHCl3) is a key raw material for producing electronic-grade polysilicon and semiconductor chips. Here, a novel approach via photocatalytic chlorination combined with simplified distillation was applied to produce electronic-grade high-purity (>99.998%) SiHCl3 in a microchannel reactor. The distillation stages can be significantly simplified by using the heart-shaped microchannel reactor during photocatalytic process. The optimal conditions of photocatalytic chlorination combined the distillation were determined: 365 nm of ultraviolet wavelength, 322.7 K of the reaction temperature, 19.8 W of the light intensity, 19.1 s of the reaction time, mol ratio of Cl2: CH3SiHCl2 is 5, 101.9 kPa of distillation pressure, and 75.3 m3/h of return flow. Multiphase-flow microreactor simulation indicated that each chamber in the reactor has a high-level impact and turbulence phenomenon, and results in the excellent mixing performance. Reactive force field molecular dynamic simulation and density-functional theory calculation determined that compared with SiHCl3, Cl· reacts extremely inclined to methyl dichlorosilane (CH3SiHCl2), especially at low temperatures. And the reaction mechanism is mainly by Cl· replacing H attached to Si in CH3SiHCl2. This feasible approach has the advantages of a purer product, simpler process, energy-saving, and economy, and is worthy of promotion.