Biomass pyrolysis coupled with non-thermal plasma/catalysis for hydrogen production: Influence of biomass components and catalyst properties

A novel two-stage pyrolysis-plasma/catalysis process has been developed for hydrogen production from waste biomass. Investigation into; the comparison of the biopolymers, cellulose and lignin; the effect of Mg, Co, Ce, Cu, Fe and Ni as promoter metals added to a Ni-Al2O3 catalyst; and the influence of the catalyst support material in relation to hydrogen production was carried out. The combination of plasma and catalysis produced the highest hydrogen and total gas yield from processing waste biomass in comparison to non-plasma pyrolysis-catalysis. The pyrolysis-plasma/catalysis of cellulose produced 4.07 mmol g−1 biomass of hydrogen compared with lignin which produced 4.29 mmol g−1 biomass of hydrogen. Metal promoters with the Ni-alumina catalyst did not have a strong influence on hydrogen production. However, some catalysts (Cu-Ni-Al2O3 and Ni-Ni-Al2O3), showed that addition of the metal promoter resulted in a reduced yield of hydrogen. The order of the catalysts in terms of hydrogen yield (H2 mmol g−1 biomass) was, Ce-Ni > Co-Ni > Mg-Ni > Fe-Ni > Ni-Ni > Cu-Ni. In addition, different catalyst support materials were investigated. Hydrogen yield was highest with alumina support material compared with titanium oxide and Y-zeolite supports. Hydrogen production was linked to the surface area and porosity, and the dielectric constant of the catalyst material.