Studies of hydrogen spillover. Part 3.—Catalysis of the reduction of metal oxides by palladium on silica

Thermal analysis (DTA and TGA) has been applied to the reduction by hydrogen of a number of metal oxides. When admixed with 5 % Pd/SiO2, certain oxides are reduced at markedly lower temperatures than in the absence of catalyst: oxides in this category include V2O5, CrO3, MoO3, WO3, UO3, Re2O7 and Co3O4. Observations are made on intermediate products formed during the course of catalysed reductions. With other oxides (CuO, Cu2O, NiO, ZnO, CdO and SnO2), the presence of the catalyst has little effect on the reduction rate. A requirement for a reduction to be catalysed is the availability of an oxidation state one below that in the oxide being reduced.