Bo Zheng, Zhu Jinhui, Yang Shiling, Yang Huachao, Yan Jianhua, Cen Kefa
State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, College of Energy Engineering, Zhejiang University Hangzhou Zhejiang Province 310027 China
RSC Adv. 2019 Mar 6;9(13):7447-7456. doi: 10.1039/c9ra00794f. eCollection 2019 Mar 1.
In-plasma catalysis has been considered as a promising technology to degrade volatile organic compounds. Heterogeneous catalysts, especially binary metal oxide catalysts, play an important role in further advancing the catalytic performance of in-plasma catalysis. This work investigates the toluene decomposition performance over Co-Ce binary metal oxide catalysts within the in-plasma catalysis. Co-Ce catalysts with different Co/Ce molar ratios are synthesized by a citric acid method. Results show that the catalytic activity of Co-Ce catalysts is obviously superior to those of monometallic counterparts. Especially, CoCeO catalyst simultaneously realizes highly efficient toluene conversion (with a decomposition efficiency of 98.5% and a carbon balance of 97.8%) and a large energy efficiency of 7.12 g kW h, among the best performance in the state-of-art literature (0.42 to 6.11 g kW h). The superior catalytic performance is further interpreted by the synergistic effect between Co and Ce species and the significant plasma-catalyst interaction. Specifically, the synergistic effect can decrease the catalyst crystallite size, enlarge the specific surface area and improve the amount of oxygen vacancies/mobility, providing more active sites for the adsorption of surface active oxygen species. Meanwhile, the plasma-catalyst interaction is able to generate the surface discharge and reinforce the electric field strength, thereby accelerating the plasma-catalytic reactions. In the end, the plasma-catalytic reaction mechanism and pathways of toluene conversion are demonstrated.
等离子体催化被认为是一种降解挥发性有机化合物的有前景的技术。非均相催化剂，尤其是二元金属氧化物催化剂，在进一步提升等离子体催化的性能方面发挥着重要作用。本工作研究了在等离子体催化条件下 Co-Ce 二元金属氧化物催化剂上的甲苯分解性能。采用柠檬酸法合成了不同 Co/Ce 摩尔比的 Co-Ce 催化剂。结果表明，Co-Ce 催化剂的催化活性明显优于单金属催化剂。特别是，CoCeO 催化剂同时实现了高效的甲苯转化（分解效率为 98.5%，碳平衡为 97.8%）以及 7.12 g kW h 的高能量效率，在现有文献报道的最佳性能（0.42 至 6.11 g kW h）范围内。Co 和 Ce 物种之间的协同效应以及显著的等离子体 - 催化剂相互作用进一步解释了其优异的催化性能。具体而言，协同效应可减小催化剂微晶尺寸、增大比表面积并提高氧空位数量/迁移率，为表面活性氧物种的吸附提供更多活性位点。同时，等离子体 - 催化剂相互作用能够产生表面放电并增强电场强度，从而加速等离子体催化反应。最后，阐述了甲苯转化的等离子体催化反应机理和途径。
