Kamsuwan Tanutporn, Guntida Adisak, Praserthdam Piyasan, Jongsomjit Bunjerd
Center of Excellence on Catalysis and Catalytic Reaction Engineering (CECC), Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
ACS Omega. 2022 Jul 14;7(29):25783-25797. doi: 10.1021/acsomega.2c03068. eCollection 2022 Jul 26.
The deterioration behaviors of Cu/ZnO/AlO (CZA) catalysts upon different Cu contents were elucidated. The fresh and spent catalysts after being used in CO and CO hydrogenation at 250 °C under atmospheric pressure were properly characterized using various techniques including X-ray powder diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction for the changes of metal sites, while the textural and chemical properties and carbon deposition on spent CZA catalysts were analyzed by N physisorption, energy-dispersive X-ray spectroscopy, and temperature-programmed oxidation. During the hydrogenation reaction for both CO and CO, the unstable Cu site on the spent CZA catalyst having a low Cu loading (sCZA-L) was oxidized to CuO and the aggregation of metal crystallite sites (Cu-ZnO and ZnO) was observed. Moreover, the amount of carbon deposition on sCZA-L (ca. >2%) is higher than the spent CZA catalyst having a high Cu loading (sCZA-H, ca. <0.5%). These phenomena led to a decrease in the surface area and the blockage of active sites. These findings can be determined on the catalytic deactivation and the obvious decrease in the catalytic activity of the CZA catalyst having a low Cu content (CZA-L, Cu:Zn = 0.8).
阐述了不同铜含量的Cu/ZnO/AlO（CZA）催化剂的劣化行为。使用包括X射线粉末衍射、X射线光电子能谱和程序升温还原等各种技术，对在250℃常压下用于CO和CO加氢反应后的新鲜和使用过的催化剂进行了适当表征，以研究金属位点的变化，同时通过N物理吸附、能量色散X射线光谱和程序升温氧化分析了使用过的CZA催化剂的织构和化学性质以及积碳情况。在CO和CO的加氢反应过程中，发现铜负载量低的使用过的CZA催化剂（sCZA-L）上不稳定的铜位点被氧化为CuO，并观察到金属微晶位点（Cu-ZnO和ZnO）的聚集。此外，sCZA-L上的积碳量（约>2%）高于铜负载量高的使用过的CZA催化剂（sCZA-H，约<0.5%）。这些现象导致表面积减小和活性位点堵塞。这些发现可以确定低铜含量（CZA-L，Cu:Zn = 0.8）的CZA催化剂的催化失活和催化活性的明显降低。
