Ethane Dehydrogenation over the Core-Shell Pt-Based Alloy Catalysts: Driven by Engineering the Shell Composition and Thickness.

Pt-based catalysts as the commercial catalysts in ethane dehydrogenation (EDH) face one of the main challenges of realizing the balance between coke formation and catalytic activity. In this work, a strategy to drive the catalytic performance of EDH on Pt-Sn alloy catalysts is proposed by rationally engineering the shell surface structure and thickness of core-shell Pt@Pt 3 Sn and Pt 3 Sn@Pt catalysts from a theoretical perspective. Eight types of Pt@Pt 3 Sn and Pt 3 Sn@Pt catalysts with different Pt and Pt 3 Sn shell thicknesses are considered and compared with the industrially used Pt and Pt 3 Sn catalysts. Density functional theory (DFT) calculations completely describe the reaction network of EDH, including the side reactions of deep dehydrogenation and C-C bond cracking. Kinetic Monte Carlo (kMC) simulations reveal the influences of the catalyst surface structure, experimentally related temperatures, and reactant partial pressures. The results show that CHCH* is the main precursor for coke formation, and Pt@Pt 3 Sn catalysts generally have higher C 2 H 4 (g) activity and lower selectivity compared to those of Pt 3 Sn@Pt catalysts, which is attributed to the unique surface geometrical and electronic properties. 1Pt 3 Sn@4Pt and 1Pt@4Pt 3 Sn are screened out as catalysts exhibiting excellent performance; especially, the 1Pt 3 Sn@4Pt catalyst has much higher C 2 H 4 (g) activity and 100% C 2 H 4 (g) selectivity compared to those of 1Pt@4Pt 3 Sn and the widely used Pt and Pt 3 Sn catalysts. The two descriptors C 2 H 5 * adsorption energy and reaction energy of its dehydrogenation to C 2 H 4 * are proposed to qualitatively evaluate the C 2 H 4 (g) selectivity and activity, respectively. This work facilitates a valuable exploration for optimizing the catalytic performance of core-shell Pt-based catalysts in EDH and reveals the great importance of the fine control of the catalyst shell surface structure and thickness.