Radiation-induced chemical reaction of methane in the presence of X- and Y-type molecular sieves

Abstract

The radiolysis of methane was investigated in the presence of X (13X) and Y (SK-40) type molecular sieves at 300°C. Product analysis showed that irradiation of methane over 13X and SK-40 produces hydrogen and hydrocarbons up to C 5. The yields of hydrocarbons, except for ethylene, over 13X and SK-40 slightly increased with irradiation time. The yields of the main hydrocarbon products over SK-40 were larger than those in the absence of molecular sieve in contrast to those over 13X. It was found that no 13X shows catalytic activity for the radiolysis of methane; on the other hand, SK-40 shows it. The relations between the proportion of hydrocarbon yield of each carbon number to the hydrocarbon total yield over 13X and SK-40 and the carbon number were the same as those in the absence of molecular sieve. It was proved by comparison of these results with those over A-type molecular sieve (5A) that the order of the catalytic activities of the molecular sieves for the radiolysis of methane differs considerably from that found in thermal catalytic reactions. These results are discussed in terms of the concept of energy transfer and the relation between the pore size of the molecular sieves andthe molecular diameters of the hydrocarbons produced.