Enhanced catalytic activity and stability over P-modified alumina supported Pd for anthraquinone hydrogenation

Abstract Pd catalysts loaded on P-doped alumina (Pd/Al2O3-xP) were prepared and applied to H2O2 production by means of anthraquinone hydrogenation. The catalytic performance over Pd/Al2O3-xP catalysts showed a volcano-shape trend with phosphorus content. Pd/Al2O3-1 P catalyst containing 1 wt% phosphorus exhibited the most excellent catalytic performance and reusability. The physicochemical properties of phosphorus-doped supports and Pd-loaded catalysts were investigated by several characterization methods. Doping phosphorus into Al2O3 increased thermal stability and adjusted surface acid intensity of the supports. Introducing suitable amount of phosphorus improved the Pd dispersion, regulated the reducibility of the catalysts. These factors contributed to the superior performance of Pd/Al2O3-1 P for the anthraquinone hydrogenation reaction. Furthermore, Pd/Al2O3 catalyst gradually deactivated during the recycle test, which was mainly attributed to Pd loss and byproduct deposition on the catalyst. Incorporation of phosphorus could enhance the anchoring effect between Pd nanoparticle and support, which could also inhibit the generation of byproducts.