Analysis of Reaction Mechanisms in CO₂ Methanation Using Quantum Chemical Calculations

Abstract

This study systematically investigates the catalytic performance of Ni-supported metal oxide catalysts in CO₂ methanation, focusing on seven supports: ZrO₂, α-Al₂O₃, γ-Al₂O₃, MgO, TiO₂, ZnO, and CeO₂. In response to carbon utilization demands, CO₂ methanation, converting CO₂ and H₂ into synthetic methane, provides a promising route for renewable fuel production and energy storage.

An integrated approach of experimental evaluation and quantum chemical calculations was employed to examine adsorption stabilities of key intermediates (e.g., OH, OCHO, and other species) and to correlate these findings with catalytic activity. Experimental results indicated that ZrO₂ achieved the highest CO₂ conversion (49.2%) and CH₄ selectivity (73.5%), followed by α-Al₂O₃ (46.0%) and CeO₂ (42.9%), while MgO displayed moderate performance. In contrast, TiO₂ and ZnO were nearly inactive under the tested conditions. Computational findings confirmed these observations, demonstrating that adsorption energy and bond order are strong predictors of efficiency.

Notably, ZrO₂ and CeO₂ were predicted to stabilize multiple reaction pathways, highlighting their versatility; Computational results provided insight into α-Al₂O₃'s high activity in specific routes. By comparing single-metal-atom and twelve-metal-atom models, it was shown that smaller systems capture essential trends, thereby reducing computational requirements.

In conclusion, these results illuminate the critical role of adsorption stability in determining CO₂ methanation performance. Optimizing electronic properties and adsorption characteristics is crucial for enhancing catalytic efficiency. The combined experimental-computational analysis provides a basis for designing Ni-supported metal oxide catalysts that advance sustainable CO₂ utilization and energy solutions. These findings offer valuable guidelines for optimizing catalyst design and improving catalytic efficiency for industry.