Unravelling the role of oxygen species in toluene oxidation over Co3O4-base catalysts: in situ DRIFTS coupled with quasi in situ XPS
Unravelling the role of oxygen species in toluene oxidation over Co3O4-base catalysts: in situ DRIFTS coupled with quasi in situ XPS
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DOI：
10.1016/j.jcat.2023.01.002
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发表时间：
2023-01
影响因子：
7.3
通讯作者：
Quanming Ren;Xiaoya Zhao;Jinping Zhong;Jin Zhang;Juntai Tian;Dengfeng Yan;Peng Liu;Mingli Fu-Mingli-F
中科院分区：
文献类型：
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作者：
Quanming Ren;Xiaoya Zhao;Jinping Zhong;Jin Zhang;Juntai Tian;Dengfeng Yan;Peng Liu;Mingli Fu-Mingli-F
本工作阐明了氧物种在Co3O4基催化剂上对甲苯氧化的作用。用Co3O4纳米针、纳米花、纳米立方体和纳米平板(分别记为Co3O4-n、Co3O4-f、Co3O4-c和Co3O4-p)通过静电吸附方法锚定铂纳米颗粒。与Co3O4催化剂相比，Pt/Co3O4催化剂对甲苯氧化的催化活性显著提高。在这些催化剂中，Pt/Co3O4-p表现出优异的催化活性，在82℃时，甲苯转化率为90%(T90=1167℃)，低于Co3O4-p(T90=249℃)。纳米铂明显增强了催化剂的低温还原能力，削弱了Co-O键能，提高了氧的迁移率和表面吸附氧的浓度。实验结果表明，甲苯在Co3O4基催化剂上氧化的主要中间体为苯甲酸盐。此外，结合准原位XPS的结果表明，在较低的反应温度(50℃)，甲苯主要由活性吸附氧物种氧化成苯甲酸酯，主要遵循Langmuir-HinShelwood机理；而在较高的反应温度(180-250℃)，甲苯主要由晶格氧物种氧化成CO2，主要遵循Mars-van Krevelen机理。
The present work elucidated the role of oxygen species in toluene oxidation over Co3O4-base catalysts. Co3O4nanoneedles, nanoflowers, nanocubes, and nanoplates (denoted as Co3O4-n, Co3O4-f, Co3O4-c, and Co3O4-p) were employed to anchor Pt nanoparticles by an electrostatic adsorption method. The catalytic activity of the Pt/Co3O4catalyst for toluene oxidation was significantly enhanced compared to that of Co3O4. Among these catalysts, Pt/Co3O4-p exhibited outstanding catalytic activity with the temperature for 90 % toluene conversion (T90= 167 °C) at 82 °C lower than Co3O4-p (T90= 249 °C). The low-temperature reducibility was obviously enhanced by the Pt nanoparticles, which weakened the Co-O bond energy, and improved the capacity of oxygen mobility and the concentration of surface adsorbed oxygen. The results ofin situDRIFTS demonstrated benzoate was identified as the dominant intermediate in toluene oxidation toward Co3O4-based catalysts. Furthermore, combined with the results ofquasi in situXPS showed that oxidizing toluene largely into benzoate primarily by the active adsorbed oxygen species at low reaction temperature (50 °C), mainly following the Langmuir-Hinshelwood mechanism, while oxidizing toluene into CO2mostly by the lattice oxygen species at high reaction temperature (180–250 °C), largely following the Mars-van Krevelen mechanism.