THERMAL COUPLING OF METHANE IN A TUBULAR FLOW REACTOR - PARAMETRIC STUDY

The thermal cracking of methane in the presence of hydrogen (H-2/CH4 ratio from 1 to 2), was investigated in a tubular flow reactor at 10(5) Pa, in the temperature range 1180-1230-degrees-C, at residence times ranging from 0.2 to 1.5 s. Reaction products were analyzed by gas-phase chromatography: products in the gaseous samples were ethylene and acetylene as major products and ethane, propene, propadiene, propane, butadiene, butenes, and cyclopentadiene as minor products. In the liquid samples (quenched) the products were benzene, toluene, xylenes, and naphthalene. Formation of coke and tar was also observed. Hydrogen dilution increases yields and selectivities Of C2 hydrocarbons, avoid carbon formation, but reduces methane conversion. The experimental results show the large effect of short residence times associated with high-temperature levels. The formation of the measured reaction products and the influence of H-2 dilution on methane conversion and on the product distribution are accounted for by a reaction model.