Effects of porous oxide layer on performance of Pd-based monolithic catalysts for 2-ethylanthraquinone hydrogenation

Pd/oxide/cordierite monolithic catalysts(oxide = AlO, SiOand SiO\\AlO) were prepared by the impregnation method. The results of ICP, XRD, SEM–EDX, XPS and Nadsorption–desorption measurements revealed that the Pd penetration depth increased with increasing the thickness of oxide layer, and the catalysts with AlOlayers had the larger pore size than those with SiOand SiO\\AlOlayers. Catalytic hydrogenation of 2-ethylanthraquinone(eA Q), a key step of the HOproduction by the anthraquinone process, over the various monolithic catalysts(60 °C, atmosphere pressure) showed that the monolithic catalyst with the moderate thickness of AlOlayer(about 6 μm) exhibited the highest conversion of e AQ(99.1%) and hydrogenation efficiency(10.0 g·L). This could be ascribed to the suitable Pd penetration depth and the larger pore size, which provides a balance between the distribution of Pd and accessibility of active sites by the reactants.