Highly dispersed and stabilized Pd species on H2 pre-treated Al2O3 for anthraquinone hydrogenation and H2O2 production

Anthraquinone hydrogenation is the core reaction in H2O2 production process. In this work, γ-Al2O3 samples with different H2 treatment temperatures (denoted as R-Al-T) were prepared to be the catalytic supports, and a series of Pd/R-Al-T catalysts were obtained by a simple impregnation method. Among the catalysts, Pd/R-Al-500 exhibits the best catalytic performance for anthraquinone hydrogenation of 10.63 g⋅L−1 hydrogenation efficiency and 885.83 gH2O2⋅gPd−1⋅h−1 H2O2 productivity, which increases by 37.7% compared with Pd/γ-Al. The stability of Pd/R-Al-500 is also significantly higher than that of Pd/γ-Al. Characterization results show the pre-treatment can construct more coordinatively unsaturated pentacoordinate Al3+ (denoted as Al3+penta) and forms more Pd-O-Al structures, which improve the Pd dispersion and synergistic effect between Pd0 and Pd2+, so as to improve the catalytic activity. Al3+penta sites also enhance the anchoring effect on Pd species and lessen the Pd leaching and agglomeration, which lead to the high stability of Pd/R-Al-500 catalyst. This work provides a simple strategy to disperse and stabilize active Pd species on γ-Al2O3 for anthraquinone hydrogenation.