Insights into aromatic methyl groups in the hydrothermal aqueous phase to enhance the efficiency of sludge gasification for hydrogen production

The present work studied the hydrogen production and transformation path of the gasification of domestic sludge with the hydrothermal aqueous phase (HTAP). The organic fractions of HTAP were found to significantly enhance the efficiency of sludge gasification for hydrogen production. FTIR and GC–MS were used to characterize the hydrothermal aqueous phase to further investigate the gasification pathways. Aromatics were found to be critical for the synergistic effect. The –CH₃ bond dissociation energies in aromatics were calculated by the density functional theory (DFT) and compared with the preliminary dissociation enthalpy of the methane reforming process. The dissociation energies of –CH₃ in the aromatics were much lower than that in methane. The contribution of the aromatics was mainly due to the disassociation of the side chain methyl groups. The dissociation of a large number of aromatic methyl groups in the HTAPs strongly promotes the reaction of methyl and water to produce hydrogen.