Highly Selective Semihydrogenation via a Wettability-Regulated Mass Transfer Process

Abstract

Desired catalytic performance can be achieved by regulating the wettability of heterogeneous catalysts. Herein, by loading palladium nanoparticles within heterostructural gel supports, we achieved the wettability-controlled selective hydrogenation of phenylacetylene (PT) into styrene (ST) or ethylbenzene (ET) in aqueous media. During catalysis, the selectivity toward ST improved significantly as the catalyst hydrophilicity increased. Additionally, catalyst’s wettability had a negligible influence on its efficiency in the hydrogenation of PT. Mechanistic studies revealed that the catalyst’s wettability has less effect on its affinity for PT but markedly influences its affinity for ST. Hydrophobic catalysts favorably adsorbed semi-hydrogenated products (ST) and fully hydrogenated them to the corresponding ET. Contrastingly, hydrogenation of PT over hydrophilic catalysts remained in a semi-hydrogenated state owing to the quick desorption of ST from the catalyst surface, resulting from weak ST-catalyst interactions. We believe that the proposed strategy will be applicable in a wide range of heterogeneous catalysis reactions.