LAUSR

Abstract Hydrogenation of 2-ethyl-anthraquinone (EAQ) has been studied over Al 2 O 3 -supported monometallic Pd and bimetallic Pd-Co, Pd-Ag, and Pd-Cu catalysts prepared by incipient wetness co-impregnation method. The catalytic performance of the bimetallic catalysts could be greatly affected by the reduction temperature and mass ratio of the second metal (M = Co, Ag, Cu) to Pd (M/Pd). The highest catalytic activity, along with the high selectivity is achieved over Pd-Co catalysts having M/Pd = 0.25 reduced at a low temperature of 80 °C, with an increase in an order of magnitude in the reaction rate compared to the monometallic Pd catalyst. This could be ascribed to the synergistic effects of the Pd-M α+ structure formed at low reduction temperature, which is confirmed by the results of H 2 -TPR, FTIR of CO adsorbed, STEM-EDX and XPS characterizations. The experimental data were satisfactorily fitted to a Langmuir-Hinshelwood (L-H) model involving a surface reaction controlling mechanism for EAQ hydrogenation. The results revealed that the surface reaction rate constant remarkably increased over bimetallic Pd-Co and Pd-Ag catalysts, implying that their superior activity is due to the more facile activation of carbonyl bond of EAQ on Pd-M α+ sites than on Pd sites.