Zhang Shuai, Wang Haozhe, Si Huayan, Jia Xiaoqian, Wang Ziyan, Li Qiang, Kong Jing, Zhang Jianbin
College of Chemical Engineering, Inner Mongolia University of Technology, Hohhot 010051, China.
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
ACS Appl Mater Interfaces. 2020 Sep 9;12(36):40285-40295. doi: 10.1021/acsami.0c09263. Epub 2020 Aug 25.
A novel core-shell (ε-MnO/CeO)@CeO composite catalyst with a synergistic effect was prepared by hydrothermal reaction and thermal decomposition and its application to high-efficiency oxidation removal of formaldehyde (HCHO) was systemically investigated. The (MnCO/CeO)@CeO precursor was prepared first by the one-pot hydrothermal reaction of Mn and Ce solutions with a CO-storage material (COSM) without any external templates or surfactants required. The thermal decomposition of the precursor afforded the core-shell (ε-MnO/CeO)@CeO composite catalyst with excellent catalytic performance. HCHO in the feed gas (180 ppm HCHO, 21% O, N balanced) at a gas hourly space velocity of 100 L/(g h) is 100% converted over the catalyst at 80 °C. The conversion rate remains above 95% in 72 h and above 73.8% in 140 h, suggesting the strong stability of the catalyst at high gas flow rates and relatively low temperatures. The synergistic mechanism of the catalyst was explored by X-ray diffraction, Raman, Brunauer-Emmett-Teller, transmission electron microscopy, and X-ray photoelectron spectroscopy. The number of defects in the catalyst and the strength of the Mn-O bond in ε-MnO can be tuned by adjusting the synthesis conditions. More oxygen vacancies on the surface of CeO can make the synergistic effect of the catalyst stronger, which significantly improves the lattice oxygen (O) activity on the surface of ε-MnO. Our work has provided new insights into the preparation of the desired composite catalysts with excellent performances.
通过水热反应和热分解制备了具有协同效应的新型核壳结构(ε-MnO/CeO)@CeO复合催化剂，并对其在高效氧化去除甲醛(HCHO)中的应用进行了系统研究。首先通过Mn和Ce溶液与储碳材料(COSM)的一锅水热反应制备了(MnCO/CeO)@CeO前驱体，无需任何外部模板或表面活性剂。前驱体的热分解得到了具有优异催化性能的核壳结构(ε-MnO/CeO)@CeO复合催化剂。在80℃、气体空速为100 L/(g h)的进料气(180 ppm HCHO、21% O₂、N₂平衡)中，HCHO在该催化剂上的转化率为100%。转化率在72 h内保持在95%以上，在140 h内保持在73.8%以上，表明该催化剂在高气体流速和相对较低温度下具有很强的稳定性。通过X射线衍射、拉曼光谱、布鲁诺尔-埃米特-泰勒比表面积测定法、透射电子显微镜和X射线光电子能谱对催化剂的协同作用机理进行了探索。通过调节合成条件，可以调节催化剂中的缺陷数量和ε-MnO中Mn-O键的强度。CeO表面更多的氧空位可以使催化剂的协同效应更强，这显著提高了ε-MnO表面晶格氧(O)的活性。我们的工作为制备具有优异性能的复合催化剂提供了新的思路。
