Catalytic properties of tricomponent metal oxides having the scheelite structure: II. Structural stability in the reduction-oxidation cycle

Abstract

Structural stability of complex metal oxide catalysts having the scheelite structure, Bi 1 − x 3 V 1 − x Mo xO 4, in the reduction-oxidation cycle is discussed on the basis of the mobility of lattice oxide ions determined by 18O 2 tracer measurements. Reduction of BiVO 4 and BiVMoO with a lower content of molybdenum, where the mobilities of lattice oxide ions are low, takes place in the vicinity of the surface layer of oxide, so that the surface structure is significantly changed after the reduction-oxidation cycle. The catalysts which contain the higher amounts of molybdenum are found to be stable during the reduction-oxidation process because rapid migration of lattice oxide ions prevents the local reduction of the catalysts.