Pyrolysis/gasification of cellulose, hemicellulose and lignin for hydrogen production in the presence of various nickel-based catalysts

Cellulose, hemicellulose and lignin are the main components of biomass. This work presents research into the pyrolysis/gasification of all three main components of biomass, in order to evaluate and compare their hydrogen production and also understand their gasification processes. A fixed bed, two-stage reaction system has been used employing various nickel-based catalysts. Gas concentration (CO, H2, CO, CO2 and CH4) was analysed for the produced non-condensed gases. Oil byproducts were analysed by gas chromatography/mass spectrometry (GC/MS). Various techniques such as X-Ray Diffraction (XRD), scanning electron microscopy (SEM) coupled to an energy dispersive X-ray spectroscopy (EDXS), temperature-programmed oxidation (TPO) were applied to characterize the fresh or reacted catalysts. The experimental results show that the lignin sample generates the highest residue fraction (52.0 wt.%) among the three biomass components. When NiZnAl (1:1) catalyst was used in the gasification process, gas yield was increased from 62.4 to 68.2 wt.% for cellulose, and from 25.2 to 50.0 wt.% for the pyrolysis/gasification of lignin. Hydrogen production was increased from 7.0 to 18.7 (m mol g−1 sample) when the NiZnAl (1:1) catalyst was introduced in the pyrolysis/gasification of cellulose. Among the investigated catalysts, NiCaAl (1:1) was found to be the most effective for hydrogen production from cellulose pyrolysis/gasification.