The methanation of CO₂, as a part of the power-to-gas concept, was studied under various industrially relevant feed compositions with a focus on the formation and influence of carbonaceous species. For this purpose, 5 wt.% Ni/Al₂O₃, 5 wt.% Ni₃Fe/Al₂O₃ and 3.4 wt.% NiRh_0.1/Al₂O₃ catalysts were prepared and characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS). During the methanation of CO₂, the Ni₃Fe catalyst emerged as the most active and selective catalyst in the mid-temperature regime (300–350 °C). At 400 °C, all three tested catalysts showed high conversion of CO₂ (67–75%; Ni > Ni₃Fe > NiRh_0.1) and selectivity towards CH₄ (95–98%). Operando Raman spectroscopy was applied to elucidate the possible influence of carbonaceous species on the performance of the catalysts. Notably, no carbon deposition was observed under various feed compositions, even in CO₂ or CO₂/CH₄ mixtures, e.g. as provided by biogas plants. Only in pure CH₄ atmosphere an intensive carbon deposition with graphitic structure occurred as uncovered by operando Raman spectroscopy. Experiments in the lab-scale reactor and a spectroscopic microreactor could be correlated and revealed a strong catalytic deactivation of the carbon covered catalysts including a pronounced shift of the selectivity towards CO. The initial activity could be recovered after reactivation in H₂ at elevated temperatures, which led to a removal of the deposits especially from the metal particles. Raman spectroscopy, supported by the results from high-resolution transmission electron microscopy (HRTEM) and EELS, revealed that carbon remained on the support material. The latter did not have any significant influence on the catalytic activity and could be removed in an oxidizing atmosphere.

作为动力制气概念的一部分，对CO ₂的甲烷化进行了各种工业相关进料组成的研究，重点是碳质物质的形成和影响。为了这个目的，5重量％的Ni / Al的₂ ö ₃，5重量％的Ni ₃的Fe / Al的₂ ö ₃和3.4％（重量）NiRh _0.1 /的Al _2种ö ₃催化剂制备和表征通过X射线衍射（ XRD），程序升温还原（TPR），扫描透射电子显微镜（STEM）结合能量色散X射线光谱（EDX）和电子能量损失光谱（EELS）。在CO ₂的甲烷化过程中，Ni₃ Fe催化剂在中温区（300–350°C）中成为最具活性和选择性的催化剂。在400°C下，所有三种测试过的催化剂均表现出较高的CO ₂转化率（67-75％； Ni> Ni ₃ Fe> NiRh _0.1）和对CH _4的选择性（95-98％）。应用Operando拉曼光谱来阐明含碳物质对催化剂性能的可能影响。值得注意的是，在各种进料组成下，甚至在例如由沼气厂提供的CO ₂或CO ₂ / CH ₄混合物中都没有观察到碳沉积。仅在纯CH _4中气氛石墨结构的碳强化沉积发生作为未覆盖的由operando拉曼光谱。可以在实验室规模的反应器和光谱微反应器上进行实验，并揭示碳覆盖催化剂的强烈催化失活，包括向CO的选择性明显转移。在H _2中活化后可以恢复初始活性在升高的温度下，这导致特别是从金属颗粒中去除沉积物。高分辨率透射电子显微镜（HRTEM）和EELS的结果支持的拉曼光谱表明，碳保留在载体材料上。后者对催化活性没有明显影响，可以在氧化气氛中除去。