Quantum-chemical cluster analysis of the mechanism of the reduction of vanadium oxide catalysts by monohydrogen. II. Octahedrally coordinated V5+ ions on a silica gel surface

The experimentally observed increase in the degree of reducibility of tetrahedrally coordinated surface ions of pentavalent vanadium on silica gel by monohydrogen following the preliminary adsorption on them of water molecules, which convert their coordination environment to an octahedral environment, has been analyzed with the aid of CINDORU unified cluster procedure. The results of the quantum-chemical analysis performed indicate that the increase may be attributed to the increase in the stability of the complexes of tetravalent vanadium formed and the increase in the role of the competitive mechanism involving the addition of the H atom to a surface V-OH group