Hydrogen production from biomass gasification with Ni/MCM-41 catalysts: Influence of Ni content

The steam pyrolysis-gasification of biomass, wood sawdust, was carried out with a Ni/MCM-41 catalyst for hydrogen production in a two-stage fixed bed reaction system. The wood sawdust was pyrolysed in the first reactor and the derived products were gasified in the second reactor. The synthesised MCM-41 mesoporous catalyst supports were impregnated with different Ni loadings (5, 10, 20 and 40 wt.%), which were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction (TPR), transmission electron microscopy (TEM) and temperature-programmed oxidation (TPO). NiO particles were homogeneously dispersed inside the pores of 5, 10, and 20 wt.% Ni/MCM-41 catalysts; however, more bulkly NiO particles (up to 200 nm particle size) were detected outside the pores with an increase of the Ni loading up to 40 wt.%. Gas production was increased from 40.7 to 62.8 wt.%, hydrogen production was increased from 30.1 to 50.6 vol.% of total gas composition when the Ni loading was increased from 5 to 40 wt.% during the pyrolysis-gasification of wood sawdust. This work showed low coke deposition (from 0.5 to 4.0 wt.%) with valuable bio-oil by-products using the Ni/MCM-41 catalyst. The highly efficient conversion of renewable biomass resource to hydrogen and bio-oil with very low coke deposition indicates that biomass gasification on Ni/MCM-41 catalysts via two-stage reaction is a promising method for the development of the biorefinery concept.

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► The NiO particles of the prepared catalyst were located inside the pores of the MCM-41 at 5 or 10 wt.% of Ni loading.
► A high dispersion of Ni was obtained for the prepared catalyst.
► Some NiO particles were formed outside the pores of the 20 or 40 wt.% Ni/MCM-41 catalyst.
► Hydrogen and gas production were increased with the increase of Ni loading during the biomass gasification process.
► Less than 4 wt.% of coke was deposited on the reacted Ni/MCM-41 catalyst.