Synergistic trimetallic Ni–Cu–Sn catalysts for efficient selective hydrogenation of phenylacetylene
Selective hydrogenation of phenylacetylene is the most effective way to remove a small amount of phenylacetylene from styrene, but it is still a challenge to develop catalysts with high activity and selectivity. Herein, a series of non-precious bimetallic Ni 3 M/SiO 2 (M = Zn, Sn, Cd, Fe, Co, Cu, or Mo) and trimetallic Ni 3 Cu–Sn/SiO 2 catalysts were prepared and applied to selective hydrogenation of phenylacetylene. A trade-off between activity and selectivity was observed on Ni 3 M/SiO 2 , where Ni 3 Cu/SiO 2 showed the best hydrogenation activity because of the hydrogen spillover effect of the Ni–Cu alloy, while Ni 3 Sn/SiO 2 exhibited the highest selectivity to styrene due to the active-site isolation effect of the Ni–Sn alloy. Impressively, trimetallic Ni 3 Cu–Sn/SiO 2 offered superior catalytic performance (94 % styrene selectivity at >99 % phenylacetylene conversion) as compared to bimetallic catalysts, owing to the synergistic effect among Ni, Cu, and Sn. In the case of Cu and Sn co-doping, the hydrogen spillover on the Ni–Cu alloy was deeply suppressed by Sn, which enabled an effective modification of the geometric and electronic structures of Ni to favor styrene desorption. The hydrogenation activity of Ni 3 CuSn 0.3 /SiO 2 can be readily enhanced by increasing the metal loading and further improved by elevating the reaction temperature and pressure, but meanwhile the high selectivity is little affected. This work demonstrates a multi-metal synergistic strategy to break the activity–selectivity trade-off of Ni-based bimetallic catalysts in the selective hydrogenation of alkynes.
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