Catalytic Activity of Nb-Si Mixed Oxides Induced by Reduction with Hydrogen

Article abstract of DOI:10.1246/bcsj.61.3839

Mixed oxides of niobium and silicium became catalytically active for butene isomerization by a reduction with hydrogen, and their catalytic activities depended on the duration of the reduction.The activity was irreversibly poisoned by oxygen.The formation of Nb⁴⁺ by the hydrogen reduction was revealed by ESR technique.Nb⁴⁺ was oxidized to Nb⁵⁺ by the admission of oxygen gas , and at the same time O2^- was formed.It was concluded that the catalytically active site on the mixed oxide surface was Nb⁴⁺ ion formed by the reduction.The importance of isolation of Nb⁴⁺ ion in silica network was suggested for the retention of the catalytic activity.