C<sub>2</sub>H<sub>2</sub> Selective Hydrogenation to C<sub>2</sub>H<sub>4</sub>: Engineering the Surface Structure of Pd-Based Alloy Catalysts to Adjust the Catalytic Performance
Wenjuan Zheng, Yuan Wang, Baojun Wang, Maohong Fan, Lixia Ling, Riguang Zhang
Abstract
The surface structure of the catalyst is a key factor to affect its catalytic performance toward the targeted reaction. In this work, aiming at revealing the surface structure influences of Pd-based alloy catalysts on the catalytic performance of C2H2 selective hydrogenation, four kinds of surface structures of Pd-based alloy catalysts, including the core–shell PdnL@M (M = Cu and Ag), the core–shell PdnL@PdxMy, the uniform alloy Pd1Cu3 and Pd1Ag1, and the subsurface structure Pd1L-Msub are engineered, and the corresponding catalytic performance is fully examined using DFT calculations. Our results reveal that the catalytic performance of C2H2 selective hydrogenation is closely related to the surface structures of Pd-based alloy catalysts; among them, the Pd1Cu3, Pd1L-Cusub, Pd1Ag1, and Pd1L-Agsub catalysts are screened out to serve as four promising candidates in the hydrogenation process, which exhibit better activity and selectivity toward gaseous C2H4 formation, especially, Pd1Cu3 and Pd1Ag1 with the uniform alloy structure. However, in the polymerization process, both Pd1L-Cusub and Pd1L-Agsub catalysts are deactivated due to the easier production of green oil, whereas both Pd1Cu3 and Pd1Ag1 catalysts effectively inhibit green oil production and present excellent thermal stability due to their ordered atomic arrangement. This work indicates the importance of rationally engineering the surface structure of Pd-based alloy catalysts, which may be applied to the design of other catalysts in C2H2 selective hydrogenation.