Development of Fe-Promoted Ni-Al Catalysts for Hydrogen Production from Gasification of Wood Sawdust

The production of renewable hydrogen-enriched gas from biomass waste is a promising technology for the development of a sustainable economy and society. Until now, there are still challenges of the technology in terms of the efficiency of hydrogen production. A catalyst is known and has been tested to enhance hydrogen production from biomass gasification, in particular, using Ni-based catalysts, which have high reactivity for hydrogen production and are cost-effective. However, developing a Ni-based catalyst with high thermal stability and resistance of coke deposition on the surface of the catalyst is still a challenging topic. In this work, Ni-Al catalysts doped with low-cost Fe metal were investigated for hydrogen-enriched syngas production from gasification of biomass using a two-stage fixed bed reactor. NiO-Fe₂O₃-Al₂O₃ catalysts with various Ni/Fe molar ratios (9:1, 8:2, 6:4, 5:5, 4:6, 2:8, and 1:9) were studied, aiming to understand the influence of Fe addition on the production of hydrogen and the catalyst stability in terms of coke deposition on the surface. X-ray diffraction, temperature-programmed reduction, and transmission electron microscopy (TEM) analysis of the fresh catalysts showed that nanoparticles (mainly NiAl₂O₄ spinel phase and Al₂O₃, ∼5 nm) were identified in the catalysts. High dispersion of metal particles was obtained using a co-precipitation method of catalyst preparation. With the increase of Fe addition, hydrogen production was reduced from around 11 to 8 mmol of H₂ g^-1 of biomass. However, the addition of Fe to the Ni-based catalyst significantly reduced the amount of coke deposited on the surface of the catalyst. The H₂/CO molar ratio was maximized to 1.28 when the Ni/Fe molar ratio was 1:1. In addition, sintering of metal particles was not observed through the TEM analysis of the fresh and reacted catalysts.