Dry Reforming of Methane Using Gd-promoted Ni/SBA-16 Catalyst: Structure, Activity and Process Optimization with Response Surface Methodology.

This work examines the effect of gadolinium (Gd) promotion on nickel-based SBA-16 catalysts for the dry reforming of methane (DRM), with the goal of improving syngas production by optimizing catalyst composition and operating conditions. Catalysts with varying Gd loadings (0.5-3 wt.%) were synthesised using co-impregnation. XRD, N2 physisorption, FTIR, XPS, and H2-TPR-CO2-TPD-H2-TPR were used to examine the structural features, textural properties, surface composition, and redox behaviour of the catalysts. XPS indicated formation of enhanced metal-support interactions, while initial and post-treatment H2-TPR analyses showed that moderate Gd loadings (1-2 wt.%) maintained a balanced distribution of reducible Ni species. The catalysts were tested for DRM performance at 800 °C and a gas hourly space velocity (GHSV) of 42,000 mL g-1 h-1. 1-2 wt.% Gd-promoted catalysts achieved the highest H2 (~67%) and CO yield (~76%). Response surface methodology (RSM) was used to identify optimal reaction conditions for maximum H2 yield. RSM predicted 848.9 °C temperature, 31,283 mL g-1 h-1 GHSV, and a CH4/CO2 ratio of 0.61 as optimal, predicting a H2 yield of 96.64%, which closely matched the experimental value of H2 yield (96.66%). The 5Ni-2Gd/SBA-16 catalyst exhibited minimal coke deposition, primarily of a graphitic character, as evidenced by TGA-DSC and Raman analyses. These results demonstrate the synergy between catalyst design and process optimization in maximizing DRM efficiency.