Selective combustion of hydrogen in the presence of hydrocarbons: 1. Pt-based catalysts

Abstract

In this communication we present experimental results showing that under certain reaction conditions the selective combustion of hydrogen in the presence of light hydrocarbons is possible over a PtSn/SiO 2 catalyst. This reaction is of importance in the development of new dehydrogenation technology based on partial combustion of hydrogen to generate heat in situ to the endothermic dehydrogenation processes. Both Sn/SiO 2 and PtSn/SiO 2 seem to be able to selectively combust hydrogen in a gas mixture with propane and oxygen, whereas Pt/SiO 2 alone is less selective. If propene is added to the gas mixture, Sn/SiO 2 is no longer able to selectively combust hydrogen. PtSn/SiO 2, on the other hand, can combust hydrogen with about 80% selectivity at 550 °C and 90% selectivity at 500 °C as long as the oxygen flow is less than half the amount of hydrogen (stoichiometry to water formation). As soon as the oxygen flow exceeds half the amount of hydrogen, the selectivity to CO x increases at the expense of water. The results show that surface reactions are involved.