Radiation-Sensitized Thermal Cracking of n-Butane. II. Ionic Reactions

Abstract

Ionic reactions in the radiolysis of n-butane were studied at temperatures ranging from 17 to 548 °C. Ionic chain reactions were found for the first time to take part in the radiation-sensitized thermal cracking mechanism of hydrocarbon system.The isobutane and isobutene yields increased with increasing temperature and at 548 °C their G-values reached 31.2 and 12.1, respectively, though they were not formed by the thermal cracking of n-butane. The formation was completely suppressed by the addition of 0.15 mol% ammonia. They were produced with high yields irrespective of the kind of wall of the irradiation cells. It was concluded from these results that isobutane and isobutene were formed by homogeneous ionic chain reactions with activation energies. Part of the propane product was also found to have been formed by ionic chain reactions. From the effect of adding n-pentane on the yields of the ionic products, C4H9+ ion was inferred as the carrier ion.In the vicinity of room temperature, formation by ionic reactions of polymers with more than 14 carbon atoms was inferred from the material balance of the products from H2 to C14.