Organosiliciumverbindungen XXII. Einfluss der Zusammensetzung des Siliciums auf die direkte Synthese der Methylchlorsilane

Thermodynamic assessment of the copper catalyzed direct synthesis of methylchlorosilanes

“…The absence of hydrogen chloride is explained by the formation of CuCl. Contrarily, Joklik and Bazant [38] found that methyl chloride decomposition in contact with copper at 300°C proceeds to a negligible extent only, whereas under the same conditions in the presence of AlCl 3 a full decomposition occurs. The decomposition of methyl chloride leads to the deposition of carbon (coke) at the surface of Experiments were performed in a fixed-bed reactor at 332°C using a copper-silicon contact mass with 10 wt% copper ( * only tetramethylsilane was calculated as side product).…”

“…Joklik and Bazant [38] studied the reaction between dimethyldichlorosilane and gaseous AlCl 3 at temperatures of 280°C and 300°C under atmospheric pressure. From the found maximum yield of 15.4% exclusively formed methyltrichlorosilane they concluded, that dimethyldichlorosilane is not involved in the reaction of Eq.…”

Effect of Low Aluminum Silicon on the Direct Process

“…The use of aluminum as a promoter has been discussed by others as well both as it is present in silicon 13 and when it is added to a MCS reactor bed. 14 Commercial MCS reactor trials with low aluminum content silicon metal were run at GE Silicones. The commercial trials were dramatic failures.…”

“…Silicon used for the MCS reaction may have a sufficient quantity of aluminum but an insufficient quantity of the correct (promoting) aluminum. The use of aluminum as a promoter has been discussed by others as well both as it is present in silicon and when it is added to a MCS reactor bed …”

Thermal cracking of CH3Cl leads to auto-catalysis of deposited coke

“…9,10 These hydrocarbons, usually referred to as coke, may deposit on the active sites, 11 reduce the productivity of (CH 3 ) 2 SiCl 2 leading to the deactivation. 12 A X-ray micro computed-tomography (micro-CT) image of coke covering the metals-based phases which catalyzed the Direct Synthesis is shown in Figure 1. High temperatures may cause the thermal cracking of CH 3 Cl.…”