Development of active oxide catalysts for the direct oxidation of methane to formaldehyde

Formaldehyde is currently produced from methane by a three-step process involving H-2/CO synthesis gas and methanol as intermediates, and development of a single-step process would have great economic incentive for producing this commodity chemical. A historical perspective is presented here in regard to the research carried out with heterogeneous metal oxide catalysts in attempts to achieve selective oxidative conversion of methane to formaldehyde. The concepts employed, both chemical and engineering, are described, and these include dual redox promoters and double-bed catalysts. More recent work in this laboratory has found V2O5/SiO2 catalysts to be very active partial oxidation catalysts. The space-time yield of and selectivity toward formaldehyde are improved by the presence of steam in the methane/air reactant mixture, and an attractive feature of the product mixture is the low quantity of carbon dioxide produced. Space-time yields of >1.2 kg CH2O/kg catalyst per h have been achieved.