Ex-situ catalytic microwave-assisted gasification of sewage sludge over Ni-modified MIL-100 (Fe) derived catalysts: Tar reforming for hydrogen-rich syngas

Catalytic tar reforming is a pivotal technology for upgrading syngas quality during sewage sludge gasification. In this study, a series of Ni-modified carbon-based catalysts (x%NiFe/C) were synthesized using MIL-100(Fe) as a precursor to investigate the impact of Ni-loading on the catalytic performance for tar reforming. Detailed characterizations, including XRD, XPS, Raman, and NH 3 -TPD, revealed that the introduction of Ni species significantly tailored the physicochemical properties of the catalysts. Specifically, the 3.3%NiFe/C catalyst exhibited the optimal specific surface area and pore structure, facilitating efficient mass transfer. Characterization results confirmed the formation of Ni-Fe alloy, which not only modulated the surface electronic density to optimize acidity but also enhanced the dispersion of active sites. The interaction between Ni and Fe species effectively promoted the cleavage of C-C and C-H bonds in tar molecules while suppressing carbon deposition. Consequently, the 3.3%NiFe/C catalyst demonstrated superior catalytic activity and stability in the two-stage microwave-assisted gasification reforming process, achieving a syngas yield of 555 mg/g·SS, a tar conversion rate of 82.9%, and an H 2 concentration of 73.8 vol%. After ten cycles, the H 2 yield and concentration remained as high as 28.0 mmol/g·SS and 68.2 vol%, respectively. This work provides mechanistic insights into the design of MOF-derived carbon-supported catalysts for efficient SS gasification.