High-performance Cr-Zr-O and Cr-Zr-K-O catalysts prepared by nanocasting for dehydrogenation of propane to propene

摘要

Ordered mesoporous Cr-Zr-O and Cr-Zr-K-O catalysts were prepared by nanocasting using a CMK-3 carbon replica as a hard template. The synthesized oxide nanoreplicas had a uniform pore-size distribution centered in the range of 5.5-6.5 nm and specific surface areas of 123-164 m~2 g~(-1). Results of physicochemical characterization (UV-vis DRS, EPR, XRD, XPS and H2-TPR) revealed that chromium species were stabilized in +3, +5 and +6 oxidation states in all samples. The developed materials exhibited excellent catalytic performance and much higher resistance to deactivation during the process of dehydrogenation of propane to propene in comparison with a material prepared without the CMK-3 hard template assistance. Potassium doping (0.2, 0.5 or 1.0 wt%) of the catalyst with a Zr/Cr atomic ratio of 5 enhanced the selectivity to propene and resistance to coke deposition.