Aqueous-phase reforming of ethylene glycol to hydrogen on Pd/Fe _3O_4 catalyst prepared by co-precipitation: Metal-support interaction and excellent intrinsic activity

摘要

A high-performance Pd/Fe_3O_4 catalyst for aqueous-phase reforming (APR) of ethylene glycol (EG) to H_2 was prepared facilely by the co-precipitation method. After proper activation, the Pd was present as highly dispersed metallic nanoparticles with dimension of <3 nm, and the Fe was present as magnetite. When compared to Pd catalyst supported on Fe_2O_3, NiO, Cr_2O_3, Al_2O_3, or ZrO_2 prepared by incipient wetness impregnation, the Pd/Fe_3O_4 catalyst displayed superior catalytic performance in terms of activity, selectivity, and stability. The intrinsic activity of the Pd/Fe_3O_4 catalyst was about three times of that of the second most active Pd/Fe_2O_3 catalyst under the same reaction conditions. In addition, the Pd/Fe _3O_4 catalyst retained ～80% of its initial activity after reaching the steady-state. Notably, the Pd/Fe_3O_4 catalyst possessed the highest turnover frequency of H_2 (109 min ~(-1)) reported so far, showing its promise as a new practical catalyst for APR of biomass-derived oxygenates to H_2. The excellent catalytic performance of the Pd/Fe_3O_4 catalyst was attributed to the enhanced synergistic effect between small Pd nanoparticles and magnetite in promoting the water-gas shift reaction, the rate-determining step in APR of EG over Pd-based catalysts.