Catalytic Disproportionation of Methyltrichlorosilane by AL-MCM-41 to Prepare Dichlorodimethylsilane

Abstract

Al-MCM-41 samples with various Si/Al ratios were prepared and then used to disproportionate methyltrichlorosilane (MTS) to produce dichlorodimethylsilane (DMCS). The catalysts were characterized by FT-IR, X-ray powder diffraction (XRD), ²⁷Al magic angle spinning nuclear magnetic resonance (²⁷Al MAS NMR), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and N₂ absorption–desorption. It reveals that all samples show the hexagonal structure of MCM-41 and exhibit large BET surface areas (over 842 m²·g^?1). FT-IR spectra of pyridine adsorption demonstrates that Al-MCM-41 samples have Lewis (L) and Brønsted (B) acidic sites, and the B acidic sites are stable in the temperature ranging from 423 to 623 K. The effects of aluminum content and temperature on the disproportionation reaction were also investigated. The results show that the Al-MCM-41 with the Si/Al ratio of 15:1 exhibits an excellent activity with 100% conversion of MTS and 47% selectivity of DMCS at 623 K under atmospheric pressure.     

甲基三氯硅烷水解反应机理的密度泛函研究

采用量子化学密度泛函方法研究了甲基三氯硅烷的结构性质和水解反应机理,发现水的O原子进攻Si原子取代Cl原子的同时,水的另一个H原子逐渐与Cl结合形成相应的羟基硅烷和HCl.甲基三氯硅烷水解按亲核取代--消除的协同反应机理完成.     

Analytics of CVD Processes in the Deposition of SiC by Methyltrichlorosilane

 Gaseous species of the thermal methyltrichlorosilane decomposition were determined qualitatively and quantitatively by in situ infrared spectroscopy and gas chromatography. Surface species like SiCl _x were detected by reflexion in situ infrared spectroscopy. A CVD mechanism of this decomposition is introduced. The comparison between the layer composition determined by EPMA and determined by gas phase analysis is given.