Nickel Supported Over Hierarchical Zeolite 13X Catalysts for Enhanced Conversion of Carbon Dioxide Into Methane

Catalytic conversion of carbon dioxide (CO₂) into useful chemicals such as methane (CH₄) is a promising carbon utilization method that effectively mitigates CO₂ and partially meets energy needs. The characteristics of commonly used nickel (Ni) supported meso/microporous catalysts for CO₂ methanation can be tailored by tuning the structural properties of the support and adding promoters. This work investigated the Ni supported over hierarchical zeolite 13X (h13X) and incorporated with different promoters (Mg, Ca, Ce, and La) developed using the wet-impregnation method. The catalysts were thoroughly characterized using SEM, EDS, XRD, H₂-TPR, CO₂-TPD, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and N₂ sorption and desorption techniques and evaluated for CO₂ methanation. The impact of promoters on the characteristics of the catalysts was observed with improved surface basicity in CO₂-TPD and metal-support interaction in H₂-TPR analysis. Among the promoted catalysts, the NiLa/h13X catalyst exhibited the highest catalytic activity with a maximum conversion of 76% and CH₄ selectivity of 98.5% at 400°C and 20 bar at GHSV of 60,000 mL g_cat⁻¹ h⁻¹, respectively. Regarding stability, the Mg-promoted catalyst exhibited better stability during 24 h of reaction than other catalysts, demonstrating better resilience against deactivation. The enhanced performance of the NiLa/h13X catalyst could be credited to the increased surface basicity, high surface area, and dispersion. This study highlights the potential of hierarchical porous zeolites for CO₂ methanation and other heterogeneous reactions.