Mediating trade-off between activity and selectivity in alkynes semi-hydrogenation via a hydrophilic polar layer.

Xiong, Jinqi; Mao, Shanjun; Luo, Qian; Ning, Honghui; Lu, Bing; Liu, Yanling; Wang, Yong · Nat Commun · 2024

basic_science · Level V

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Abstract

As a crucial industrial process for the production of bulk and fine chemicals, semi-hydrogenation of alkynes faces the trade-off between activity and selectivity due to undesirable over-hydrogenation. By breaking the energy linear scaling relationships, we report an efficient additive-free WO<sub>3</sub>-based single-atom Pd catalytic system with a vertical size effect of hydrogen spillover. Hydrogen spillover induced hydrophilic polar layer (HPL) with limited thickness on WO<sub>3</sub>-based support exhibits unconventional size effect to Pd site, in which over-hydrogenation is greatly suppressed on Pd<sub>1</sub> site due to the polar repulsive interaction between HPL and nonpolar C=C bonds, whereas this is invalid for Pd nanoparticles with higher altitudes. By further enhancing the HPL through Mo doping, activated Pd<sub>1</sub>/MoWO<sub>3</sub> achieves recorded performance of 98.4% selectivity and 10200 h<sup>-1</sup> activity for semi-hydrogenation of 2-methyl-3-butyn-2-ol, 26-fold increase in activity of Lindlar catalyst. This observed vertical size effect of hydrogen spillover offers broad potential in catalytic performance regulation.