Effect of γ-irradiation and doping with MoO3 and V2O5 on surface and catalytic properties of manganese oxides

The effects of gamma-irradiation (0.2-1.6 MGy), thermal treatment and doping with MoO3 and V2O5 (0.25-4 mol%) on the surface and catalytic properties of manganese oxides prepared by thermal decomposition of manganese carbonate at 400degreesC and 600degreesC have been investigated. The techniques employed were X-ray diffraction, nitrogen adsorption at -196degreesC, oxidation of CO by O-2 at 120-220degreesC and decomposition of H2O2 at 20-50degreesC. The results revealed that irradiation decreased the particle size of manganese oxides, increased their specific surface areas, decreased the amount of surface excess oxygen and decreased their catalytic activities. The doping with MoO3 and V2O5 conducted at 600degreesC brought about a measurable decrease in the BET-surface area and catalytic activities of the treated solids. These results were discussed in terms of splitting of manganese oxide particles and removal of chemisorbed oxygen by treating with gamma-irradiation and formation of manganese molybdate and vanadates by treating with the used dopant oxides. (C) 2002 Elsevier Science Ltd. All rights reserved.