Structure/metathesis-activity relations of silica supported molybdenum and tungsten oxide

In this study the influence of metal content and impregnation technique (wet or dry) on struture and metathesis activity for silica supported molybdenum and tungsten oxide is described. Structural aspects are obtained from several techniques, in particular temperature programmed reduction and Raman spectroscopy. Catalytic activity has been measured in a six-channel microflow reactor. A combination of structural and metathesis activity data leads to the conclusion that in these systems the precursors for the catalytic sites in metathesis are surface compounds and not the bulk oxides. The results suggest that a prerequisite for catalytic activity is a combination of a high degree of dispersion and an easy reducibility