Effect of Ni particle location within the mesoporous MCM-41 support for hydrogen production from the catalytic gasification of biomass

Thermal processing of biomass in the presence of a catalyst is a promising technology to generate H-rich gases for fuelling the future. Metal particles loaded on porous supports have been widely used for biomass gasification. However, no detailed research has been designed for describing the catalytic performance of nickel particles located inside compared to outside the pores of the supports. In this work, two groups of Ni/MCM-41 catalysts were prepared: I-series catalysts where most of the NiO particles were located inside the mesopores of MCM-41 and O-series catalysts where most of the NiO particles were located outside the pores of MCM-41. The prepared catalysts were used in the pyrolysis-catalytic gasification of wood sawdust using a two-stage fixed-bed reaction system. Gasification on the I-series catalysts generated more gas and hydrogen and lower oil, compared with the O-series catalysts. Hydrogen production was increased from 16.46 to 21.26 (mmol H g wood) when the catalyst was changed from 20%Ni-O to 20%Ni-I. The better performance of the I-series catalysts in relation to hydrogen production is suggested to be due to the longer residence time of pyrolysis reactants inside the pores of the MCM-41 and thus a longer contact time between reactants and active Ni sites. In addition, the high dispersion of the fine NiO particles inside the pores of the MCM-41 support enhances the catalytic performance of the I-series catalyst during the pyrolysis/gasification of biomass.