Non-Oxidative Propane Dehydrogenation on CrO(x)-ZrO(2)-SiO(2) Catalyst Prepared by One-Pot Template-Assisted Method

A series of CrO(x)-ZrO(2)-SiO(2) (CrZrSi) catalysts was prepared by a “one-pot” template-assisted evaporation-induced self-assembly process. The chromium content varied from 4 to 9 wt.% assuming Cr(2)O(3) stoichiometry. The catalysts were characterized by XRD, SEM-EDX, temperature-programmed reduction (TPR-H(2)), Raman spectroscopy, and X-ray photoelectron spectroscopy. The catalysts were tested in non-oxidative propane dehydrogenation at 500–600 °C. The evolution of active sites under the reaction conditions was investigated by reductive treatment of the catalysts with H(2). The catalyst with the lowest Cr loading initially contained amorphous Cr(3+) and dispersed Cr(6+) species. The latter reduced under reaction conditions forming Cr(3+) oxide species with low activity in propane dehydrogenation. The catalysts with higher Cr loadings initially contained highly dispersed Cr(3+) species stable under the reaction conditions and responsible for high catalyst activity. Silica acted both as a textural promoter that increased the specific surface area of the catalysts and as a stabilizer that inhibited crystallization of Cr(2)O(3) and ZrO(2) and provided the formation of coordinatively unsaturated Zr(4+) centers. The optimal combination of Cr(3+) species and coordinatively unsaturated Zr(4+) centers was achieved in the catalyst with the highest Cr loading. This catalyst showed the highest efficiency.