Hydrogen production by aqueous phase reforming of sorbitol using bimetallic Ni-Pt catalysts: metal support interaction

摘要

Hydrogen was produced by Aqueous Phase Reforming (APR) of 10% (w/w) sorbitol using mono- and bi-metallic catalysts of Ni and Pt supported on alumina nano-fibre (Alnf), mesoporous ZrO2 and mixed oxides of ceria-zirconia-silica (CZxS) with varying concentration of silica (where x is silica concentration). X-ray diffraction, TEM/EDS and temperature programmed reduction were also carried on these catalysts to study the surface properties. It was observed that co-impregnation of Pt and Ni in atomic ratio 1:12 increased the reducibility of Ni by forming an alloy. However, sequential impregnation of Ni followed by Pt does not form the bi-metallic particles to increase the Ni reducibility. Reduction peak of co-impregnated Ni-Pt/Alnf was found to be 270 °C lower than the sequentially impregnated Pt/Ni/Alnf. The presence of silica at high concentration in CZxS support decreased the reducibility of ceria by forming an amorphous layer on Ce_xZr_(1-x)O_2 crystals, which also decreased Ni reducibility. The rate of H2 formation from aqueous phase sorbitol reforming was found to be highest for co-impregnated Ni-Pt catalysts followed by sequentially impregnated Pt/Ni and monometallic Ni catalyst. The H2 activity decreased in the following order of the supports: Alnf > ZrO2 > CZ3S > CZ7S.