Enhancement of hydrogen production in steam gasification of sludge: Comparing different strategies for deeper conversion of hydrogen sources in biomass

Biomass has significant advantages in the gasification process but is frequently hampered by low hydrogen production. In this study, sludge and hydrothermal aqueous phase (HTAP) were selected as biomass substrates to provide a plentiful source of organic hydrogen for gasification, and different strategies for deeper conversion of hydrogen sources and higher hydrogen production were compared. Solid acid catalysts were used to alter the distribution of organic hydrogen sources in biomass substrates. Ni-ore-based catalysts were used to directly catalyze the gasification process. The results showed that nickel-ore-based catalysts exhibited a much higher contribution to hydrogen production. The solid acid catalyst resulted in the dissociation of methyl and methoxy on the side chain of HTAP, and the transfer of hydrogen source affects the subsequent hydrogen production. And Ni-ore-based catalysts efficiently can convert the hydrogen sources in tar into valuable gas. The Ni-ore-based catalysts achieved up to 62.07% increase in hydrogen production from gasification. This study elucidates the underlying mechanistic issues of the proposed strategies to produce hydrogen from gasification and provides a deeper understanding of the efficient utilization of hydrogen sources in biomass.