DataSheet1_Graphene nanoplatelets promoted CoO-based catalyst for low temperature CO2 methanation reaction.pdf

Methanation of CO2 is an important reaction for reducing CO2 emissions in a power-to-gas system. Compared to cobalt supported on gamma-Al2O3, cobalt supported on graphene nanoplatelets (GNPs) showed significantly better performance for CO2 methanation. Cobalt supported on GNPs was capable of 15% conversion of CO2 to CH4 at temperatures below 250°C, compared to 5% for cobalt supported on Al2O3. In situ thermogravimetric analysis (TGA) demonstrated that the Co/GNP catalyst was stable to 400°C. The maximum catalyst mass-specific CH4 yield was obtained at a Co loading of 5wt% on GNPs; however, high Co loading on GNPs deactivated the reactivity of the Co/GNP catalyst. Transmission electron microscopy (TEM) demonstrated that 5wt% Co/GNPs had the smallest and most dispersed cobalt nanoparticles. Excessive loading of cobalt tended to form isolated large Co nanoparticles. X-ray photoelectron spectroscopy (XPS) and Raman spectrometry revealed that more CoO phases were maintained on the surface of 5wt% Co/GNPs, indicating that the interaction between the Co and the GNPs had more of an impact on cobalt’s redox capacity than did particle size, which ultimately affected cobalt’s active phase during the CO2 reduction process. Furthermore, Raman spectrometry demonstrated that Co loading led to an increase in graphene defects. Higher Co loading on GNPs resulted in fewer interfaces between Co and GNPs due to the agglomeration of Co nanoparticles.

二氧化碳的甲烷化反应是电力至气体系统中降低二氧化碳排放的重要反应。相较于负载于γ-Al2O3上的钴，负载于石墨烯纳米片（GNPs）上的钴在二氧化碳甲烷化方面表现出显著优异的性能。负载于GNPs的钴能够在低于250°C的温度下实现高达15%的二氧化碳转化为甲烷的转化率，而负载于Al2O3上的钴仅为5%。原位热重分析（TGA）证实了Co/GNP催化剂在400°C下仍保持稳定。在GNPs上负载5wt%的钴时，获得了最大的催化剂质量特定的甲烷产量；然而，GNPs上高负载的钴会降低Co/GNP催化剂的活性。透射电子显微镜（TEM）显示，5wt%的Co/GNPs具有最小且分布最广的钴纳米颗粒。钴的过量负载倾向于形成孤立的大型钴纳米颗粒。X射线光电子能谱（XPS）和拉曼光谱研究表明，5wt%的Co/GNPs表面上保留了更多的CoO相，这表明钴与GNPs之间的相互作用对钴的氧化还原能力的影响大于颗粒尺寸，这最终影响了钴在二氧化碳还原过程中的活性相。此外，拉曼光谱表明，钴负载导致了石墨烯缺陷的增加。GNPs上较高的钴负载由于钴纳米颗粒的聚结，导致钴与GNPs之间的界面减少。