The active sites and catalytic properties of CrOx/Zn-Al2O3 catalysts for propane dehydrogenation

The CrOx-based catalysts supported on Zn-modified alumina were prepared for propane dehydrogenation. The CrOx/Zn-Al2O3 catalysts possess uniform foamed pores with high specific surface area and large pore size. The zinc enriched on the surface of alumina changes the surface energy and acid sites, which decreases interaction between chromium and support so that increases the particle size of crystal Cr2O3 and changes the distribution of Cr species. The dispersion of Cr6+ species on the Zn-modified alumina is improved, and the zinc promotes the formation of more active oligomeric and polymeric chromate on the surface and highly dispersive non-redox Cr3+ species in pore channel simultaneously, which chromium species exhibit high propane conversion and propylene yield. The zinc modifier obviously inhibits the formation of coke deposition to increase catalyst stability.