PYROLYSIS OF METHANE IN THE PRESENCE OF HYDROGEN

The kinetics of methane pyrolysis were studied in a tubular flow react or in the temperature range 1200 to 1500 degrees C at atmospheric pres sure. To avoid excessive carbon formation the reaction time was short and the methane feed was diluted with hydrogen. Ethene, ethyne, benzen e and hydrogen were the main gaseous products. Ethane was observed as a product at very low conversions of methane. More than 90% selectivit y was obtained for C-2 products, The ratio of ethyne to ethene increas ed with increasing temperature. The yield of C-2 products is limited b y gas-phase equilibrium at lower temperatures. Formation of carbon was strongly depressed by hydrogen at higher temperatures. The maximum yi eld of ethyne was found to increase from about 10% to about 50% when t he temperature was increased from 1200 to 1500 degrees C, with hydroge n dilution H-2:CH4 = 2:1. A mechanistic reaction model was used to sim ulate the pyrolysis of methane at the actual conditions. A sensitivity analysis was performed to evaluate the elementary reactions which inf luence the formation and consumption of the species in the model syste m.