Applied Catalysis B: Environmental, Vol.239, 102-113, 2018
Supported ionic liquid-like phases based on CMS/DVB with different NR3 cations as catalysts for the chlorosilanes disproportionation
The variety of catalysts based on macroporous supported ionic liquid-like phases using chloromethyl styrene cross-linked with divinylbenzene (CMS/DVB) and different NR3 cations was investigated for disproportionation of trichlorosilane in a continuous-flow reactor. To determine the optimal conditions for conducting a complex catalytic process, the primary task is to determine the thermodynamical equilibrium state of the reaction system. Increase in the concentration of DCS in the system occurs from 5 to 10%, which in turn is promising in terms of considering DCS as the main precursor for the processes of epitaxial silicon growth. In addition, the maximum attainable temperature is thermodynamically optimal for the process. In the first stage, the thermal stability of the catalyst supports was determined using evolved gas analysis and all samples have a similar thermal stability 475 K. All samples have been carefully studied by SEM, AFM, EGA and nitrogen physisorption. To compare the catalytic activity of different catalytic systems on the basis of macroporous supports modified by different tritic ammonium functional groups with the subsequent activation, the kinetics of the TCS disproportionation on the catalyst sample having the highest catalytic activity was studied. The results obtained indicate that the introduction of acceptor substituents increases catalytic activity in the disproportionation of TCS. To assess the feasibility of using dichlorosilane (DCS) as a raw material for the creation of semiconductor structures, the kinetics of thermal decomposition of DCS in a mixture with hydrogen was studied at a temperature of 1200-1500 K. According to the obtained kinetic results, the activation energy of the process is determined, which is in the temperature range of 1220-1320 K and the concentration of DCS in hydrogen 9-28.6 mol.%, is 112.9 kJ/mol. Activation energy value indicates the kinetical mode of the thermal decomposition.
Keywords:Trichlorosilane;Disproportionation;Supported ionic liquid-like phases;Silane;Heterogeneous catalysis