The synthesis of Au–X (X = Pt, Pd) nanoalloys based on Bi as an intermediate using the galvanic replacement reaction method for electrocatalytic reaction.

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.

Boron chloride in the chlorosilane is hard to remove and directly impacts the quality of polysilicon produced by improved Siemens method. Silicon dioxide functionalized with mannitol and citric acid successfully removed boron chloride in organic solution. The effects of immersion concentration and drying temperature were studied to attain the best adsorption performance. The sorption phenomenon was described well by pseudo-second-order kinetic model and Langmuir adsorption isotherm; particle diffusion model proved that the adsorption on the active adsorption site was the rate determining step, with the formation of boronic esters. Thermal stability and degradation kinetic of the adsorbents were investigated by thermogravimetric analysis. The characterization results of Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray energy spectrometry, and BET showed the silicon dioxide was successfully functionalized by oxygen-containing functional groups, leading to be a better and safer substitute to traditional boron-selective chelating resin.