Reactive oxygen species on platinum gauzes during partial oxidation of methane into synthesis gas

Platinum gauzes have been studied for the partial oxidation of methane in a high-temperature TAP-2 reactor between 800 and 1100 degrees C. Two different oxidation procedures were used and the oxygen uptake has been measured. Alternating pulse experiments with oxygen and methane with various pulse intervals have revealed mechanistic information about the platinum catalyzed partial oxidation. It has been shown that carbon monoxide and hydrogen can be produced directly from methane and solid oxidized platinum. In the absence of gas phase oxygen, the maximum selectivities to carbon monoxide and hydrogen were 97 and 96%, respectively, at a methane conversion of 25%. At low surface oxygen concentrations, oxygen that is incorporated in the platinum bulk diffuses back to the surface to react with surface carbon to carbon monoxide. In that case the surface lifetimes of carbon monoxide and hydrogen are much shorter than the oxygen diffusion time and no consecutive oxidation reactions occur. The results of this study show that production of synthesis gas with high yields is possible by a direct route. (C) 2000 Academic Press.