Unraveling the Interplay between Nonthermal Plasma and Metal Oxide Catalysts in Propane Dehydrogenation Reaction

Plasma technology is a promising method for activating small molecules. Propane (C3H8) dehydrogenation (PDH) is a strong endothermic reaction that faces thermodynamic limitations, which is expected to be addressed by plasma technology. Investigating the interplay of the plasma and catalysts, as well as its impact on PDH, is significant for designing efficient plasma mediated PDH systems. Herein, we report a strong interplay between plasma and catalysts during the PDH reaction, which determines the enhancement performance. It was observed that the consumption rate of C3H8 can be greatly boosted in plasma-mediated conditions over three representative metal oxide catalysts, i.e., Co/Al2O3, Ga/Al2O3, and V/Al2O3. Discharge power calculations suggest that the activation of C3H8 by nonthermal plasma is primarily in the form of vibrational excitation, which reduces the activation energy required for the PDH and thus enhances the consumption rate of C3H8. A systematic study of the metal oxide catalysts by manipulating the number of active sites and the molecules of the vibrational excited state of C3H8 revealed a strong interplay between plasma and catalysts. For plasma-mediated PDH reactions, the rate increases with the loading of metal oxides, followed by a constant value in high-loading regions. In contrast, the values increased monotonically under the same conditions under pure thermal conditions. This suggests that the PDH performance in plasma-mediated conditions is determined by both the number of active sites and the amount of vibrationally excited molecules, while that for the pure thermal reaction is solely dictated by the number of active sites. This work is expected to advance the rational design of plasma-assisted systems with the optimal performance for more sustainable catalysis.