Tuning oxygen vacancy concentration of MnO2 through metal doping for improved toluene oxidation
Tuning oxygen vacancy concentration of MnO2 through metal doping for improved toluene oxidation
复制标题
通过金属掺杂调节 MnO2 的氧空位浓度以改善甲苯氧化
DOI：
10.1016/j.jhazmat.2020.122181
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发表时间：
2020-06-05
影响因子：
13.6
通讯作者：
Ren, Yewei
中科院分区：
文献类型：
--
作者：
Dong, Cui;Qu, Zhenping;Ren, Yewei
氧空位对MnO 2的化学性质起着重要的调节作用。本文通过掺杂Cu ~（2+）制备了不同氧空位浓度的二维MnO_2催化剂。研究了在Cu ~（2+）掺杂过程中，水钠锰矿型MnO_2层间的K ~+物种可以被置换。同时，这一过程会产生氧空位。有趣的是，在MnO 2中形成适当数量的氧空位明显增强了低温还原活性和氧物种活性，这提高了甲苯氧化的催化活性（T-100 = 220 ℃，E-a= 43.6 kJ/ mol）。但过量的氧空位不利于提高MnO 2催化剂的甲苯氧化活性。利用原位漫反射红外光谱研究了具有中等浓度氧空位的MnO 2-OV 3催化剂的主要中间产物和转化途径。结果表明，吸附态甲苯可与催化剂上的氧物种相互作用，形成物理吸附的苯甲醛、苯甲酸盐和苯甲酸盐物种。此外，还发现氧空位浓度对苯甲酸盐物种的氧化起着重要的影响，这是由于氧空位对气态氧的活化具有加速作用。
Oxygen vacancy acts an important role in adjusting the chemical properties of MnO2. In this paper, two-dimensional MnO2 catalysts with different oxygen vacancy concentration are obtained by doping Cu2+. It is researched that the K+ species in the interlayer of birnessite-type MnO2 can be substituted during the Cu2+ doping process. Meanwhile, this process will generate the oxygen vacancy. Interestingly, the formation of an appropriate numbers of oxygen vacancy in MnO2 distinctly enhances the low-temperature reducibility and oxygen species activity, which improves the catalytic activity for the toluene oxidation (T-100 = 220 degrees C, E-a= 43.6 kJ/ mol). However, an excessive concentration of oxygen vacancy in MnO2 sample performs against the activity improvement for toluene oxidation. In situ DRIFTS are applied to elucidate the main intermediates and conversion pathway on MnO2-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.