Weiman Li, Haidi Liu, Min Zhang, Yunfa Chen
State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences Beijing 100190 China
University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing 100049 China.
RSC Adv. 2019 Oct 1;9(53):31035-31042. doi: 10.1039/c9ra05098a. eCollection 2019 Sep 26.
In this work, a series of mesoporous Ni Mn Ce ternary oxides were prepared to investigate their NO catalytic oxidation ability. The sample NiMnCe showed a 95% NO conversion at 210 °C (GHSV, ∼80 000 h). Characterization results showed the good catalytic performance of NiMnCe was due to its high specific surface area, more surface oxygen and high valance manganese species, which can be ascribed to the incorporation of three elements. Based on the results of XRD, H-TPR, O-TPD and XPS, we confirmed the existence of Ni + Mn → Ni + Mn, Ce + Ni → Ce + Ni in NiMnCe, and the oxidation-reduction cycles were proved to be helpful for NO oxidation. The results from an DRIFTS study indicated the presence of bidentate nitrate and monodentate nitrate species on the catalyst's surface. The nitrate species were proved to be intermediates for NO oxidation to NO. A nitrogen circle mechanism was proposed to explain the possible route for NO oxidation. Nickel introduction was also helpful to improve the SO resistance of the NO oxidation reaction. The activity drop of NiMnCe was 13.15% in the presence of SO, better than MnCe (25.29%).
在本工作中，制备了一系列介孔镍锰铈三元氧化物以研究其对NO的催化氧化能力。样品NiMnCe在210℃（气体时空速，约80000 h⁻¹）下NO转化率达95%。表征结果表明，NiMnCe良好的催化性能归因于其高比表面积、更多的表面氧和高价态锰物种，这可归因于三种元素的掺入。基于XRD、H-TPR、O-TPD和XPS的结果，我们证实了NiMnCe中存在Ni⁺+Mn→Ni⁰+Mn⁺、Ce⁴⁺+Ni⁰→Ce³⁺+Ni⁺，且氧化还原循环被证明有助于NO氧化。漫反射红外傅里叶变换光谱（DRIFTS）研究结果表明催化剂表面存在双齿硝酸盐和单齿硝酸盐物种。硝酸盐物种被证明是NO氧化为NO₂的中间体。提出了一个氮循环机制来解释NO氧化的可能途径。引入镍还有助于提高NO氧化反应的抗SO₂性能。在有SO₂存在的情况下，NiMnCe的活性下降为13.15%，优于MnCe（25.29%）。
