Selective Oxidation of Methane To Formaldehyde At Ambient Pressure: The Role of Dopants In Determining Optimum Carrier Loading For The Molybdena/Silica System

Conversion of methane to formaldehyde from a 5:1 mixture of methane and nitrous oxide was investigated between 500 and 600C for a range of molybdena catalysts supported on silica. This support was also modified by treatment with a range of additives (sodium, phosphorus or copper) prior to impregnation with ammonium heptamolybdate. An optimal molybdena loading could be defined for each support; modification of the support generally increased the optimal molybdena loading so that higher conversions could be achieved without loss of selectivity. These changes are rationalised in terms of a modification of the redox properties of the supported molybdena.