Atomically dispersed Pd catalysts for the selective hydrogenation of succinic acid to γ-butyrolactone

Abstract

Heterogeneous palladium catalysts with high atom-efficiency offer practical value for selective hydrogenation. Here, we prepared atomically dispersed Pd species supported on γ-AlOOH nanosheets (Pd/γ-AlOOH), which contain clusters and dominated single atoms. Even with an extremely low amount of Pd loading, the catalytic activity of 0.1Pd/γ-AlOOH leads to 50.3% of succinic acid conversion at 4h. At the time, the succinic acid conversion reaches 90.7% and 97.1%, and the selectivity to γ-butyrolactone is high up to 96.9% and 93.8% over 0.5Pd/γ-AlOOH and 1.0Pd/γ-AlOOH, respectively. The supported Pd single atom (Pd1/γ-AlOOH) Exhibits 30- and 1100-fold increase in the catalytic activity compared with the supported clusters Pd13/γ-AlOOH and Pd55/γ-AlOOH for the selective hydrogenation of succinic acid to γ-butyrolactone, respectively. Analysis of the structural properties confirms that Pd single atoms on γ-AlOOH (010) surface have high adsorption energy, which is in agreement with catalytic efficiency. In addition, Pd single atoms in the catalyst 0.2Pd/γ-AlOOH account for 86.6% of the overall catalytic activity and can serve as the most efficient catalytic active sites.