Comparative study of α-, β-, γ- and δ-MnO2 on toluene oxidation: Oxygen vacancies and reaction intermediates
Comparative study of α-, β-, γ- and δ-MnO2 on toluene oxidation: Oxygen vacancies and reaction intermediates
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α-、β-、γ-和δ-MnO2对甲苯氧化的比较研究：氧空位和反应中间体
DOI：
10.1016/j.apcatb.2019.118150
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发表时间：
2020-01-01
影响因子：
22.1
通讯作者：
Li, Junhua
中科院分区：
文献类型：
--
作者：
Yang, Wenhao;Su, Zi'ang;Li, Junhua
研究了α-、β-、γ-和δ-MnO 2催化剂的结构与性能的关系。四种样品在隧道尺寸、表面活性氧和氧化还原性质方面表现出不同的甲苯氧化活性。在60,000 mL·g（-1）·h（-1）的空速下，K+存在于层间的δ-MnO 2催化剂的甲苯氧化活性最高，且具有良好的耐水性。HAADF图像和EELS结果表明，氧空位优先通过Mn 4+还原形成在具有层堆叠位错的δ-MnO 2晶格上，而不是结晶良好的β-MnO 2。这些含杂阳离子K+的固有畸变结构改善了氧空位的出现-湮灭循环。原位DRIP IS的结果表明，甲苯吸附通过快速脱氢甲基由于丰富的表面吸附氧δ-MnO 2促进。此外，苯甲酸酯，马来酸和碳酸锰上的δ-MnO 2的甲苯氧化过程中，在相对较低的温度下的关键中间物种。
The structure-performance relationship of alpha-, beta-, gamma- and delta-MnO2 catalysts were studied. The four samples exhibited different activities of toluene oxidation in terms of distinct tunnel sizes, surface-active oxygen and redox properties. delta-MnO2 catalyst with K+ in the mezzanines of its layers presented the highest toluene oxidation activity under a GHSV of 60,000 mL.g(-1) h(-1), as well as good water resistance. HAADF images and EELS results showed that oxygen vacancies preferred to form on delta-MnO2 lattice with layer stack dislocations via Mn4+ reduction rather than beta-MnO2 with good crystallization. These inherent-distorted structures with heterocations K+ improved the emerge-annihilate cycling of oxygen vacancies. In-situ DRIP IS results showed that toluene adsorption was facilitated via rapid dehydrogenation of methyl due to abundant surface adsorbed oxygen on delta-MnO2. In addition, benzoate, maleic and manganese carbonate on delta-MnO2 were the key intermediate species during toluene oxidation at relatively low temperatures.