A Study of Grafted Vanadium Oxides & V/Zr Mixed Oxides on Alumina

This book discusses studies pursued to identify the vanadium and zirconium oxidation states involved in successful catalytic production of hydrogen from steam reforming of hydrocarbons and alcohols. Vanadium oxides and vanadium/zirconium mixed oxides were loaded on to the support using grafting techniques. It was observed that the reaction of the respective, metal alkoxide precursors proceeded with surface hydroxyl groups slowly. These reactions resulted in “single sites” of the metal oxides on the surface with sub-monolayer to monolayer coverage. The loadings were controlled by the various reaction conditions and also by the size of the precursor molecules. In co-grafting studies in all the reactions the Zr/V ratio in the feed was four. Surprisingly, very low zirconium loading was observed on the catalyst surface and in most cases it was lower than the corresponding vanadium loading. From TPR and XPS studies V4+ & V5+ were the oxidation states observed under both normal and rigorous reducing conditions.