Heterogeneous catalysis offers one of the sustainable solutions to the global warming challenge by converting greenhouse gases, particularly carbon dioxide (CO2), into valuable chemicals, notably methane (CH4). The CO2 methanation is a thermodynamically favorable and scalable process, typically carried out using nickel (Ni) based catalysts. However, the intense exothermicity of the methanation reaction poses challenges, including sintering of Ni nanoparticles and carbon deposition, which critically undermine the catalyst's stability. Resilience of the catalyst can be enhanced by tuning the metal-support interaction (MSI) and regulating the dispersion of Ni nanoparticles. 

The aim of this thesis was to develop stable and robust Ni catalysts by tuning the MSI and dispersion of Ni nanoparticles supported over the hierarchical zeolite 13X (h13X). Preliminary experiments demonstrated that Ni loading, activity, and instability of the catalyst are correlated. Under optimized synthesis conditions, grafting functional groups onto the support resulted in a stronger MSI and preferentially deposited Ni nanolayers, thereby enhancing the activity and stability of the catalyst. The addition of the cobalt cocatalyst strengthened the MSI and stabilized the catalyst's performance, notably during the initial stages of CO2 methanation. The synergistic effect of surface modification and cocatalyst resulted in lower activation energy, higher activity, and increased stability of the catalyst. Additionally, the influence of oxide promoters (La, Ca, Mg, Ce) proved to be dependent on their specific characteristics, with a notable increase in surface basicity, MSI, and catalyst stability. 

Based on the outcomes of surface modification and traditional catalyst design, a metal-chelation strategy was explored to regulate the size of Ni nanoparticles. The Ni was coordinated to the amine-based ligands, including pyridine, bipyridine, diethylenetriamine, and oleylamine, followed by their impregnation on the support. Remarkable differences were observed in the characteristics of the catalysts depending upon the type of ligand. A broader Ni distribution was observed for the heterocyclic ligand, whereas better textural properties were achieved by the aliphatic amines, which were attributed to the coordination of Ni in the metal-chelate complexes and the strength of interaction with the support. Besides the catalyst’s design, the process parameters, including temperature, pressure, H2/CO2 ratio, gas hourly velocity, and gas composition, showed a profound impact on the CO2 conversion, CH4 selectivity, and stability of the catalysts. overall, this thesis offers insights into regulating the catalyst's MSI, dispersion, distribution, activity, and stability.