Our recent experiments for CO₂ methanation reveal that Co catalysts supported on ZrO₂ and Al₂O₃ exhibit good initial activity, but the Co/ZrO₂ catalyst is catalytically more active and more stable than the Co/Al₂O₃ catalyst. Detailed characterization demonstrated that there are notable differences in the adsorption properties of key species between the ZrO₂- and Al₂O₃-supported catalysts and in the metal-support interactions where Co/ZrO₂ shows enhanced adsorption for key species and better reducibility of the cobalt oxide. In the present work, we performed density functional theory (DFT) calculations to provide theoretical insight into the support effect over Co/ZrO₂ and Co/Al₂O₃ for CO₂ methanation in terms of adsorption and activation of key species. The relative adsorption strengths of CO₂, H₂, CO, and CH₄ species on Co/ZrO₂ and Co/Al₂O₃ calculated by DFT showed qualitative agreement with experimental TPD. Importantly, DFT results uncovered an energetically more favorable H₂ dissociative adsorption, faster H* surface migration, and more facile Co-O bond cleavage on Co/ZrO₂ than on Co/Al₂O₃, thus rationalizing the experimentally observed lower temperature and higher degree of cobalt oxide reduction on the ZrO₂ support.

我们最近的CO ₂甲烷化实验表明，负载在ZrO ₂和Al ₂ O ₃上的Co催化剂具有良好的初始活性，但Co / ZrO ₂催化剂比Co / Al ₂ O ₃催化剂具有更高的催化活性和稳定性。详细的表征表明，在ZrO _2-和Al ₂ O ₃负载的催化剂之间，关键物质的吸附性能和Co / ZrO ₂的金属-载体相互作用之间存在显着差异。显示出对关键物质的吸附增强，并且氧化钴的还原性更好。在目前的工作中，我们进行了密度泛函理论（DFT）计算，以就关键物质的吸附和活化方面提供对Co / ZrO ₂和Co / Al ₂ O ₃对CO ₂甲烷化的支持作用的理论见解。DFT计算得到的CO ₂，H ₂，CO和CH ₄物种在Co / ZrO ₂和Co / Al ₂ O ₃上的相对吸附强度与实验TPD的定性一致。重要的是，DFT结果揭示了在能量上更有利的H ₂与Co / Al ₂ O ₃相比，在Co / ZrO ₂上具有离解吸附，更快的H *表面迁移和更容易的Co-O键裂解，因此使实验观察到的较低温度和较高氧化钴在ZrO ₂载体上的还原程度合理化。