Reaction Mechanism of Mn-Mediated Synergistic Modulation of Anti-Coking Properties and Syngas Optimization in NiAl Catalysts

Aiming at the problem of high carbon emissions during carbonate pyrolysis under the dual-carbon strategy, Mn-doped modified NiMnAl catalysts were prepared via the sol-gel method in this work. The as-prepared NiMnAl catalysts exhibited remarkable performance improvement at 750 ℃. Compared with pristine NiAl catalysts, the CH₄ conversion rate increased from 11% to 16%, the H₂/CO volume ratio approached 1, and the carbon deposition decreased by more than 20%. Characterization results revealed that Mn doping enhanced lattice oxygen mobility through electronic structure rearrangement and the in-situ formation of MnO₂ active phases. Meanwhile, the specific surface area increased from 63.215 m²/g of the NiAl catalyst to 82.087 m²/g of the NiMnAl catalyst, accompanied by an optimized pore structure. The synergistic mechanism endows the catalyst with high catalytic activity and excellent carbon deposition resistance. Thermogravimetric analysis showed that the initial oxidation temperature of carbon deposits decreased, and the carbon deposition was further reduced by introducing a small amount of O₂. X-ray diffraction (XRD) and BET（Brunauer-Emmett-Teller）specific surface area measurements indicated that oxygen-introducing conditions can effectively alleviate the damage of pore structure caused by carbon deposition. This study provides a theoretical basis for the development and industrial application of high-efficiency anti-carbon-deposition catalysts.