Enhanced catalytic performance of transition metal-doped Cr2O3 catalysts for propane dehydrogenation: A microkinetic modeling study

Abstract

The catalytic behavior of M1-Cr2O3 (M = Mn-Cu, Ru-Ag, and Os-Au) in propane dehydrogenation (PDH) has been studied by employing microkinetic modeling combined with results from periodic DFT + U calculations. Calculated results indicate that most of the single atoms concerned can be stably present on the Cr2O3 surface. The adsorption energy calculations and Bader charge analysis demonstrate that the acidity of the O sites adjacent to the M sites would be enhanced upon doping, which in turn strengthens the atomic H adsorption and the co-adsorption of various PDH species. The surface H formation energy is identified as the reactivity descriptor for PDH over the M1-Cr2O3 catalysts, and a volcano curve of the PDH activity is obtained. By calculating the difference between the propylene dehydrogenation and desorption barriers, it is found that some M1-Cr2O3 catalysts show improved selectivity towards propylene, as compared to Cr2O3. Comparison between the formation barriers of H2 and H2O reveals that single-atom doping has no apparent negative effect on the catalytic stability of the Cr2O3 surface. The Cu1-Cr2O3 catalyst is finally identified as the most promising catalyst for PDH among the 13 M1-Cr2O3 catalyst candidates, considering the catalytic activity, selectivity, stability, and cost.