Study On The Catalysts Of The Synthesis Of Methylchlorosilane

Organochlorosilanes are the foundation of the organosilicone industry. The Rochow direct process, which silicone and methyl chloride under catalysis form methyl chlorosilane, is the core synthesis technique for the commercial production of organosilicones. In this paper the mass ratios of catalyst to promoters in the direct process are investigated, and the catalysts were charactered with different methods, in order to analyse the mechanism of catalysis, enhance the selectivity of the dimethyldichlorosilane.The kinetics of Rochow direct process was studied in a fixed-bed reactor of 10 mm inner diameter. The methylchlorosilanes were synthesized via the Rochow direct process with the catalysts, i.e., the electrolytie copper powder, the atomized copper powder, the copper powder made by different methods(made in wet or dry condition), nano copper powder and several other kinds of copper powder, the different selectivity effects of different copper powder with proper promoters used in the direct process were reviewed, the selectivity effects of different mass ratios were compared, and the catalysts of the direct process were optimized in the endThe methylchlorosilane product in the direct synthesis is a complex compound, which contains dimethyldichlorosilane as the majority and some trimethylchlorosilane, methyltrichlorosilane, low-boiling products and high-boiling products. With GC the three main products can be detected via internal calibration curve method with benzene as the internal standard, they can be analyzed quantitatively. The results indicated that tendency of selectivity of dimethyldichlorosilane versus reaction time was increasing in the beginning, decreasing whereafter, the peak selectivity of dimethyldichlorosilane appeared at the ratio of 10:1:0.25 of silicon, copper and zinc if using nano copper powder.All kinds of copper powder and the solid residue after adding different promoter were treated and charactered by Field Scanning Electron Micrograph, X-rayDiffraction Instrument and Particle Size Analyzer. The results indicated that the specific surface area of the electrolytie copper powder and the atomized copper powder were smaller than others, and the surface were felsiter, therefore, they were hard to form the active center, also hard to synthesize the objective product. The contrast of other several kinds of copper powder indicated the copper powder with big specific surface area, alveolate or scraggly surface appearance was easy to form active center, synthesize methylchlorosilane. The results of XRD revealed that the e-phase after adding tin into the contact was stronger than that unadded, meanwhile, the r)-phase was quite weaker, reducing the selectivity of dimethyldichlorosilane.