Determining the Role of Cerium Hydride during CO2 Methanation

CO2 methanation (CO2 + 4H2 → CH4 + 2H2O) is a promising strategy for chemically storing renewable H2. For this reason, we have developed a highly active inverse ceria-based catalyst, CeO2/Co. In our previous studies, a clear oxidation and unit cell parameter expansion of ceria was seen in H2 atmosphere, indicative of Ce-hydride (Ce-H) formation. Our results suggest that this species might play an important role in the catalytic properties of this system. However, we have not yet been able to perform operando experiments on catalysts with and without Ce-H. Here, we propose to use XRD to determine the varying Ce-H content and transition metal (TM) oxidation state of catalysts and link it to the overall activity and selectivity of the catalyst for CH4 formation.

二氧化碳甲烷化（CO₂ methanation，CO₂ + 4H₂ → CH₄ + 2H₂O）是化学存储可再生氢气的一种极具前景的策略。为此，我们开发了一种高活性的反式二氧化铈基催化剂CeO₂/Co。在先前的研究中，我们观察到二氧化铈在氢气氛围下出现明显的氧化现象及晶胞参数膨胀，这表明铈氢化物（Ce-H）的形成。我们的结果提示，该物种可能在该体系的催化性能中发挥重要作用。然而，我们尚未能对含与不含铈氢化物的催化剂进行原位操作实验。在此，我们提出利用X射线衍射（XRD）测定催化剂中铈氢化物含量的变化及过渡金属（TM）的氧化态，并将其与催化剂生成甲烷的整体活性和选择性相关联。