Oxidative dehydro-isomerization of n-butane over anion-promoted Cr2O3/ZrO2catalysts

The oxidative dehydrogenation and isomerization of n-butane to isobutene wa s investigated over several Cr2O3/ZrO2 catalysts modified by some acidic an ions. The effects of acidic promoters on the Cr2O3/ZrO2 catalysts on the pr operties and catalytic behavior were studied. The modified Cr2O3/ZrO2 catal ysts show varying surface physicochemical properties depending on the natur e of anions. Addition of anion promoters reduces the surface area and redox potential and it also induces a remarkable change in acid strength. Howeve r, the change in the acid site distributions only occurred on the sulfated zirconia- and tungstated zirconia-supported catalysts. Modification of Cr2O 3/ZrO2 by acidic anions decreases the butane conversion while it increases the butene and isobutene selectivities, which can be attributed to the vari ation of the redox property and acid sites.