Yang Qilei, Li Qi, Wang Xiyang, Wang Xiao, Li Lei, Chu Xuefeng, Wang Dong, Men Jishuai, Li Xinbo, Si Wenzhe, Peng Yue, Ma Yongliang, Li Junhua
State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China.
Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
ACS Appl Mater Interfaces. 2022 Jan 19;14(2):2860-2870. doi: 10.1021/acsami.1c20965. Epub 2022 Jan 7.
A diesel oxidation catalyst (DOC) is installed upstream of an exhaust after-treatment line to remove CO and hydrocarbons and generate NO. The catalyst should possess both good oxidation ability and thermal stability because it sits after the engine. We present a novel high-performance DOC with high steam resistance and thermal stability. A selective dissolution method is adopted to modify the surface physicochemical environment of CeO-SmMnO. The X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, Raman, electron paramagnetic resonance, hydrogen temperature-programmed reduction, and temperature-programmed desorption results reveal that surface Sm cations are partially removed with the exposure of more Mn and Ce cations and the presence of active surface oxygen species. This mechanism benefits the oxygen transformation from Ce to Mn and promotes the Ce + Mn ↔ Ce + Mn redox cycle according to the in situ near-ambient pressure X-ray photoelectron spectroscopy and in situ diffuse reflectance infrared Fourier transformation spectroscopy results. Under laboratory-simulated diesel combustion conditions, the catalyst demonstrates excellent low-temperature oxidation catalytic activity (CO and CH conversion: = 250 °C) compared to a Pt-based catalyst (CO and CH conversion: = 310 °C) with a WHSV of 120,000 mL g h. Specifically, NO conversion reaches 68% when the temperature is approximately 300 °C.
柴油氧化催化剂（DOC）安装在排气后处理管线的上游，用于去除一氧化碳和碳氢化合物并生成一氧化氮。由于该催化剂位于发动机之后，因此应具备良好的氧化能力和热稳定性。我们提出了一种具有高抗蒸汽性和热稳定性的新型高性能DOC。采用选择性溶解方法来改变CeO-SmMnO的表面物理化学环境。X射线光电子能谱、X射线吸收光谱、拉曼光谱、电子顺磁共振、氢气程序升温还原和程序升温脱附结果表明，随着更多的锰和铈阳离子暴露以及活性表面氧物种的存在，表面钐阳离子部分被去除。根据原位近常压X射线光电子能谱和原位漫反射红外傅里叶变换光谱结果，这种机制有利于氧从铈向锰的转化，并促进Ce + Mn ↔ Ce + Mn氧化还原循环。在实验室模拟的柴油燃烧条件下，与具有120,000 mL g h空速的铂基催化剂（一氧化碳和碳氢化合物转化率： = 310 °C）相比，该催化剂表现出优异的低温氧化催化活性（一氧化碳和碳氢化合物转化率： = 250 °C）。具体而言，当温度约为300 °C时，一氧化氮转化率达到68%。
