Dong Cui, Qu Zhenping, Jiang Xiao, Ren Yewei
Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Linggong Road 2, Dalian, 116024, China.
Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Linggong Road 2, Dalian, 116024, China.
J Hazard Mater. 2020 Jun 5;391:122181. doi: 10.1016/j.jhazmat.2020.122181. Epub 2020 Jan 22.
Oxygen vacancy acts an important role in adjusting the chemical properties of MnO. In this paper, two-dimensional MnO catalysts with different oxygen vacancy concentration are obtained by doping Cu. It is researched that the K species in the interlayer of birnessite-type MnO can be substituted during the Cu doping process. Meanwhile, this process will generate the oxygen vacancy. Interestingly, the formation of an appropriate numbers of oxygen vacancy in MnO distinctly enhances the low-temperature reducibility and oxygen species activity, which improves the catalytic activity for the toluene oxidation (T = 220 °C, E=43.6 kJ/mol). However, an excessive concentration of oxygen vacancy in MnO sample performs against the activity improvement for toluene oxidation. In situ DRIFTS are applied to elucidate the main intermediates and conversion pathway on MnO-OV3 with moderate concentration of oxygen vacancy. The results demonstrate that the adsorbed toluene can interact with oxygen species of catalyst to form physisorbed benzaldehyde, aldehydic adsorbate and benzoate species. In addition, it is found that the oxygen vacancy concentration plays an important effect on the oxidation of benzoate species owing to the acceleration effect of oxygen vacancy in the activation of gaseous oxygen.
氧空位在调节MnO的化学性质方面起着重要作用。本文通过掺杂Cu获得了具有不同氧空位浓度的二维MnO催化剂。研究发现，在Cu掺杂过程中，水钠锰矿型MnO层间的K物种可被取代。同时，该过程会产生氧空位。有趣的是，MnO中适量数量氧空位的形成显著提高了低温还原性和氧物种活性，从而提高了甲苯氧化的催化活性（T = 220°C，E = 43.6 kJ/mol）。然而，MnO样品中过量的氧空位浓度不利于甲苯氧化活性的提高。采用原位漫反射红外傅里叶变换光谱（in situ DRIFTS）来阐明具有中等氧空位浓度的MnO-OV3上的主要中间体和转化途径。结果表明，吸附的甲苯可与催化剂的氧物种相互作用形成物理吸附的苯甲醛、醛类吸附物和苯甲酸盐物种。此外，发现由于氧空位在气态氧活化中的加速作用，氧空位浓度对苯甲酸盐物种的氧化有重要影响。
