Oxidative dehydro-isomerization of n-butane over anion-promoted Cr2O3/ZrO2 catalysts

The oxidative dehydrogenation and isomerization of n-butane to isobutene was investigated over several Cr2O3/ZrO2 catalysts modified by some acidic anions. The effects of acidic promoters on the Cr2O3/ZrO2 catalysts on the properties and catalytic behavior were studied. The modified Cr2O3/ZrO2 catalysts show varying surface physicochemical properties depending on the nature of anions. Addition of anion promoters reduces the surface area and redox potential and it also induces a remarkable change in acid strength. However, the change in the acid site distributions only occurred on the sulfated zirconia- and tungstated zirconia-supported catalysts. Modification of Cr2O3/ZrO2 by acidic anions decreases the butane conversion while it increases the butene and isobutene selectivities, which can be attributed to the variation of the redox property and acid sites.