(521s) Structure - Activity Relationship of Ni-Ru/?-Al2O3 Catalyst for CO2 Methanation Reaction.

Catalytic CO₂ methanation serves as a technique to restrain the growing greenhouse CO₂ emissions by converting CO₂ to CH₄ which serves as a valuable stored renewable power source. In our current research, we focus on low temperature CO₂ methanation catalyzed by highly active bimetallic Ni-Ru/γ-Al₂O₃ catalysts. In general, the cause of high activity of Ni-Ru/γ-Al₂O₃ catalyst is not clear, with some studies attributing it to the Ru segregation while others ascribing it to the dispersed Ru on the Ni surface. Here, in our current research we specifically focus on establishing a structure-activity relationship for Ni-Ru/γ-Al₂O₃ catalysts at various Ru loading using a combination of modelling and experimental tools. To begin with, Molecular Dynamics (MD) simulations were performed with Gupta potential for Ni (‘x’ mole%)-Ru (‘y’ mole%) ((‘x’=99.5, 95 and 85) (‘y’=0.5, 5 and 15)) bimetallic catalysts. The MD simulations showed a dispersed morphology of Ru throughout the Ni nanoparticle for all the investigated catalysts. Subsequently, we performed lab-scale experiments to validate the catalyst structure as deciphered from the MD simulations. Ni-Ru/γ-Al₂O₃ catalysts (Identical Ni: Ru mole% as in MD simulations) were synthesized by employing the wetness impregnation method and their crystalline phases were investigated by X-ray Diffraction (XRD) analysis. Next, we plan to investigate the elemental composition and particle size distribution of Ni and Ru in the synthesized catalysts with the aid of Scanning Transmission Electron Microscopy – Energy dispersive X-ray (STEM-EDX) analysis. Subsequently, to analyze the near surface composition of the synthesized catalysts, we plan to perform X-ray Photoelectron Spectroscopy (XPS) analysis. The deciphered and validated catalyst structure information will be used to develop a reaction mechanism with quantitative information of kinetic parameters. Finally, we plan to establish a performance level relationship between the model and reactor-level experimental data on catalyst activity and reactivity.