Synergistic role of Fe in enhancing coke resistance and long-term stability of Ni/MgAl2O4 catalysts during dry reforming of methane

Dry reforming of methane (DRM) offers a promising approach for converting CH₄ and CO₂ into synthesis gas; however, catalyst deactivation caused by coke formation and metal sintering remains a major challenge. In this work, Ni/MgAl₂O₄, Fe/MgAl₂O₄, and Ni–Fe/MgAl₂O₄ catalysts were developed using a MgAl₂O₄ support prepared by co-precipitation and metal incorporation via wet impregnation. The catalysts were evaluated for DRM at 750 °C under 80 h time-on-stream conditions, and the effects of Fe addition on activity, syngas production, structural stability, and coke evolution were investigated using XRD, BET, H₂-TPR, H₂-chemisorption, XPS, Raman spectroscopy, TPO, and TGA analyses. The Ni–Fe/MgAl₂O₄ catalyst exhibited the highest performance, achieving initial CH₄ and CO₂ conversions of 93% and 95%, with H₂ and CO yields of 87.4% and 91.18%, respectively. After 80 h, it maintained CH₄ and CO₂ conversions of 84.6% and 85.2% with an H₂/CO ratio of 0.97. In contrast, Ni/MgAl₂O₄ showed severe deactivation, with CH₄ conversion decreasing from 71% to 39.1%. Characterization results revealed that Fe incorporation improved metal dispersion, strengthened Ni–Fe interaction, and suppressed Ni particle growth during reaction. Moreover, coke analysis confirmed a significant reduction in carbon deposition from 12.86 mmol C/g cat for Ni/MgAl₂O₄ to 2.48 mmol C/g cat for Ni–Fe/MgAl₂O₄. The enhanced DRM performance of the bimetallic catalyst is attributed to stabilized active sites and reduced formation of stable carbon species, demonstrating the effectiveness of Ni–Fe interactions for improving long-term DRM stability.