Effect of Calcination Atmosphere on the Structure and Catalytic Behavior of Cr2O3/Al2O3 Catalysts for Dehydrogenation of Propane

In this paper, the Cr2O3/Al2O3 catalysts with various loadings and calcination processes were prepared to investigate catalytic performance in the dehydrogenation of propane. Interestingly, it was found that the Cr2O3/Al2O3 catalysts by post-treatment of air calcination achieved higher propane conversion than their counterparts calcined by H2/Ar, while the latter exhibited a better anticoking ability and then higher resistance against deactivation. XRD, Raman spectra, UV-vis spectra, H2-TPR, XPS, and NH3-TPD investigations showed that the Cr6+ species with different polymeric degrees at low loading and crystalline Cr2O3 at high loading were observed on the Cr2O3/ Al2O3 catalysts calcined in air, which exhibited a higher Cr6+/Cr3+ ratio, a larger amount of H2 consumption, and concentration of surface acid sites. On the contrary, the post-treatment by H2/Ar effectively prevented the polymerization of the monomeric and/or oligomeric chromate species by the reduction of Cr6+ species, and the non-redox surface Cr3+ clusters or microcrystalline with good dispersion are the dominant species for all of the Cr2O3/Al2O3-H2/Ar catalysts. The characterization results demonstrated that the calcination atmosphere has a great impact on the nature of Cr species, the dispersion, and the surface acidity, which may account for the difference in the catalytic performance of propane dehydrogenation to propylene.

Automated summary

This study investigates the catalytic performance of Cr2O3/Al2O3 catalysts with different loadings and calcination processes in the dehydrogenation of propane. The results show that the catalysts calcined by air achieved higher propane conversion, while those calcined by H2/Ar exhibited better anticoking ability and resistance against deactivation. The difference in catalytic performance is attributed to the nature of Cr species, the dispersion, and the surface acidity.