Fabrication of Supported Pd-Ir/Al2O3 Bimetallic Catalysts for 2-Ethylanthraquinone Hydrogenation

A series of chi wt % Pd-(1-chi) wt % Ir (chi = 0.75, 0.50, and 0.25) catalysts supported on gamma-Al2O3 have been prepared by co-impregnation and calcination-reduction, and subsequently employed in the hydrogenation of 2-ethylanthraquinonea key step in the manufacture of hydrogen peroxide. Detailed studies showed that the size and structure of the bimetallic PdIr particles vary as a function of Pd/Ir ratio. By virtue of its small metal particle size and the strong interaction between Pd and Ir, the 0.75 wt % Pd-0.25 wt % Ir/Al2O3 catalyst afforded the highest yield of H2O2, some 25.4% higher than that obtained with the monometallic 1 wt % Pd catalyst. Moreover, the concentration of the undesired byproduct 2-ethyl-5,6,7,8-tetrahydroanthraquinone (H(4)eAQ) formed using the Pd-Ir bimetallic catalysts was much lower than that observed with the pure Pd catalyst, which can be assigned to the geometric and electronic effects caused by the introduction of Ir. (C) 2017 American Institute of Chemical Engineers