Vapor-Phase Oxidation of Hydrocarbons. Part 2. Effect of Oxygen Concentration on Platinum-Catalyzed Combustion and Ionization

摘要

The catalytic combustion of hydrocarbons has been studied further, with particular attention given to the ionization phenomena associated therewith. The greater ion yield of highly branched alkanes relative to straight-chain alkanes was confirmed. The effect of the concentration of O2 in the gas mixture on the extent of oxidation and ionization varied with the hydrocarbon used. In general, increase in O2 content caused considerable enhancement of the ion yield. However, with some hydrocarbons the fraction oxidized decreased markedly with increased O2 concentration. The data seem consistent with an explanation based on lower temperature oxidation occurring only on the Pt surface, whereas at higher temperatures the catalytic process extends itself to some degree into the vapor phase. It is also suggested that dissociative adsorption of O2 at higher temperatures is involved in the ion-producing process. (Author)