The role of lattice oxygen on the activity of manganese oxides towards the oxidation of volatile organic compounds
The role of lattice oxygen on the activity of manganese oxides towards the oxidation of volatile organic compounds
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DOI：
10.1016/j.apcatb.2010.07.007
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发表时间：
2010-08-31
影响因子：
22.1
通讯作者：
Figueiredo, J. L.
中科院分区：
文献类型：
--
作者：
Santos, V. P.;Pereira, M. F. R.;Figueiredo, J. L.
一系列结构、组成、平均锰氧化态和比表面积不同的锰氧化物已用于挥发性有机化合物（VOC）的全氧化。选择乙醇、乙酸乙酯和甲苯作为VOC的模型。在测试的锰氧化物中，发现钾锰矿（KMn8O16）在VOC的氧化中非常活跃。其他相（即 Mn2O3 和 Mn3O4）的存在对锰矿的性能有显着影响。程序升温实验与 X 射线光电子能谱 (XPS) 相结合表明氧物质的迁移率和反应性受到显着影响，这解释了这些样品的催化性能。 Mn3O4由于增加了晶格氧的反应活性和迁移率而提高了催化性能，而Mn2O3则具有相反的效果。这些结果表明，锰氧化物的氧化还原性能和催化性能之间存在相关性。吸附甲苯或乙醇后的程序升温表面反应（TPSR）以及进料中无氧情况下进行的反应表明，晶格氧参与了VOC氧化机制。研究发现转化水平受到 VOC 类型的影响，CO2 的反应性按以下顺序增加：甲苯 < 乙醇 < 乙酸乙酯。 VOC 的类型尤其重要，因为每种 VOC 都会影响催化剂的还原，从而影响气相中氧气的掺入速率。甲苯降低了氧的迁移率，因此氧在晶格中的结合速率较慢，这解释了观察到的较低的转化率。 (C) 2010 Elsevier B.V. 保留所有权利。
A series of manganese oxides differing in the structure, composition, average manganese oxidation state and specific surface area have been used in the total oxidation of volatile organic compounds (VOC). Ethanol, ethyl acetate and toluene were chosen as models of VOC.Among the manganese oxides tested, cryptomelane (KMn8O16) was found to be very active in the oxidation of VOC. The performance of cryptomelane was significantly affected by the presence of other phases, namely, Mn2O3 and Mn3O4. Temperature-programmed experiments combined with X-ray photoelectron spectroscopy (XPS) show that the mobility and reactivity of the oxygen species were significantly affected, explaining the catalytic performances of those samples. Mn3O4 improves the catalytic performance due to the increase of the reactivity and mobility of lattice oxygen, while Mn2O3 has the opposite effect. These results show that there is a correlation between the redox properties and the catalytic performance of the manganese oxides.Temperature-programmed surface reactions (TPSR) after adsorption of toluene or ethanol, in addition to reactions performed without oxygen in the feed, show that lattice oxygen is involved in the VOC oxidation mechanism. The conversion level was found to be influenced by the type of VOC, the reactivity into CO2 increasing in the following order: Toluene < Ethanol < Ethyl Acetate. The type of VOC is particularly important, as each VOC affects the reduction of the catalyst and, consequently, the incorporation rate of oxygen from the gas phase. Toluene decreases the oxygen mobility, so there is a slower incorporation rate of oxygen in the lattice, which explains the lower conversions observed. (C) 2010 Elsevier B.V. All rights reserved.