Surface properties and reactivity of Al2O3-supported MoO3 catalysts in ethane oxidative dehydrogenation

The effect of MoO3 loading on the properties and the catalytic performance of a series of alumina-supported molybdena catalysts (0-30 wt% MoO3) was investigated in the oxidative dehydrogenation of ethane. The molybdena species on alumina were found to be amorphous at submonolayer coverages. At higher loadings, the formation of Al-2(MoO4)(3) crystallites was detected by XRD. XPS revealed the existence of both Mo(VI) and Mo(V) sites on the catalyst surface, the concentration of which depends on the MoO3 loading. In terms of catalytic performance, the activity increases with increasing loading in the submonolayer regime, decreasing for higher loadings. High selectivity to ethene is obtained even at relatively high conversion levels for catalysts exceeding monolayer coverage.