The conversion of methane on 12-tungstophosphoric acid in the presence of dichloro- or tetrachloromethane

Abstract

The introduction of small quantities of dichloro- or tetrachloromethane to the feed stream in the conversion of methane on silica-supported 12-tungstophosphoric acid produces substantial changes in the conversion, selectivity, and rates of consumption of reactants and formation of products. With 0.4% tetrachloromethane in the feed stream the selectivity to CH 3Cl and conversion of methane at 450 °C were approximately 80 and 1 mol%, respectively, over a 5 wt% loaded catalyst. Elimination of the oxidant N 2O from the feed stream produced a marked decrease in the yield of CH 3Cl suggesting a pivotal role of the oxidant in the chlorination process. The conversions, selectivities, and rates are also shown to depend on the loading of the catalyst, the reaction temperature, and the ratio of CH 4 to N 2O. Evidence is presented to show that the process apparently operates through the incorporation of chlorine in the catalyst, although the form of the latter is at this time unknown. Although the conversions are low the high selectivity to methyl chloride provides considerable attraction for this new route for the conversion of methane.