Partial oxidation of methane to oxygenates by oxygen transfer at novel lattice oxygen sites of palladium and ruthenium bimetal oxide

Abstract

Alumina-supported bimetal oxide (PdRuOx) catalysts were prepared by galvanic displacement reduction method for partial oxidation of methane into oxygenates, and evaluated in a fixed-bed reactor at relatively low temperatures of 280–310 °C, using a mixture of NO and O2 as the oxidant. The bimetal oxide catalysts exhibited high selectivity to HCHO. However, CO2 was dominantly obtained over two alumina-supported monometal oxide (PdO and RuO2) catalysts. Characterizations results showed that bimetal oxide-PdRuOx species with Pd-(O)-Ru active sites can selectively convert CH4 to HCHO through the transfer of its novel lattice oxygen. And in this process, CH3OH may play as an intermediate. Compared to oxidation with either O2 and NO, the mixture oxidant of NO and O2, acting as an oxygen shuttle through the gas-phase reaction of NO+1/2 O2→NO2, promoted the selective formation of HCHO.