Gas-phase hydrodechlorination of mixtures of chloromethanes with activated carbon-supported platinum catalysts

摘要

Platinum catalysts supported on activated carbon (Pt/C) at different metal loadings (0.5-2% Pt) have been tested in the gas-phase hydrodechlorination (HDC) of mixtures of dichloromethane (DCM) and chloroform (TCM), with a total feed concentration of 1000ppmv. Almost complete dechlorination was achieved at 250°C, 1kghmol-1 space time and a H2/CM molar ratio of 25 with the 2% Pt catalyst. At a reaction temperature of 250°C, scarce inhibition in the conversion of both compounds was observed compared to the HDC of the individual chloromethanes. The TOF values for DCM increase with the Pt content, which can be attributed to the higher proportion of the zero-valent species. The selectivity to reaction products suggests a parallel reactions scheme. The catalysts showed a high stability, demonstrated by the unchanged conversion of both chloromethanes upon time on stream in long-term experiments carried out at up to 26h.