Theoretical and experimental investigations into light alkane dehydrogenation over chromium-containing catalyst

Abstract

To avoid potential economic and technical risks in a hybrid C3/C4 alkane dehydrogenation plant, it is of great importance to better understand the similarities and differences of propane and isobutane dehydrogenation. However, few investigations on this issue have been conducted. To fulfill the research gap, a combined Density Functional Theory (DFT) and experimental investigation has been carried out in this work. Our findings indicate that, in the adsorption phase, both alkanes are apt to adsorb onto the tetra-coordinate Cr(4) site of the Cr2O3(0001) catalytic surface. But isobutane has a stronger adsorption capability than propane. In the dehydrogenation phase, both alkanes follow the stepwise C–H bond activation mechanism rather than the concerted mechanism. However, the activation energy required for isobutane dehydrogenation (i.e., 2.10 eV) is a bit lower than that for propane (i.e., 2.19 eV). The findings are also confirmed by experiments. It is believed that the present work discloses the similarities and differences of propane dehydrogenation (PDH) and isobutane dehydrogenation (BDH) on the same Cr-catalyst and could be used to guide the rational design, optimization and control of hybrid alkane dehydrogenation plants.