Hydrogen production from biomass via hydrothermal gasification using Ni–Ce catalysts supported on Kaolin

Ni–Ce bimetallic material was supported on Kaolin by impregnation, calcination, and reduction for hydrothermal gasification of crop residues at 340–400 °C and 16–30 MPa. According to orthogonal experiments, the optimal reaction conditions were determined to be 380 °C, 5 min, 0.5 g cotton stalk and 0.5 g catalyst. H 2 yield was enhanced from 1.85 mmol/g to 21.82 mmol/g, with the specific surface area increasing from 4.74 m 2  g −1 (Bulk Ni) to 26.46 m 2  g −1 (Ni–Ce/c-Kaolin catalyst), indicating that Kaolin improved the dispersion of active Ni species. The bimetallic Ni–Ce synergy is reflected by broader reduction peaks of the Ni–Ce catalyst in H 2 -TPR. The variation of cerium valence states in XPS revealed that Ce is dynamically involved in oxygen transfer, promoting catalytic activity in coexisting Ce 3+ /Ce 4+ oxides. The Ni–Ce/c-Kaolin catalyst developed in this study provides an efficient route to hydrogen production from agricultural waste, thereby demonstrating its potential for high-value conversion of sustainable biomass resources.