Catalytic oxidation of benzene by ozone over manganese oxides supported on USY zeolite
Catalytic oxidation of benzene by ozone over manganese oxides supported on USY zeolite
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DOI：
10.1016/j.jcat.2013.05.016
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发表时间：
2013-09-01
影响因子：
7.3
通讯作者：
Ogata, Atsushi
中科院分区：
文献类型：
--
作者：
Einaga, Hisahiro;Teraoka, Yasutake;Ogata, Atsushi
本文报道了以高硅铝比沸石（SiO_2/Al_2O_3 = 180）为载体的锰氧化物在臭氧存在下对苯氧化的催化性能。采用N2吸附、X射线吸收精细结构（XAFS）和程序升温还原（TPR）等方法对催化剂进行了表征。通过常规浸渍技术，锰氧化物以3+氧化态高度分散在Y型沸石中，它们是臭氧氧化苯的活性中心。在313-373 K下，在干燥和潮湿条件下获得稳态活性。在这两种条件下，臭氧消耗量，苯氧化，和考克斯形成之间观察到很强的相关性。反应气体中的水蒸气通过促进催化剂对副产物化合物的氧化而增强苯的氧化，并且水蒸气因此略微改善CO2选择性。傅立叶变换红外光谱（FTIR）和程序升温氧化（TPO）研究表明，苯在催化剂上被氧化生成了弱结合的甲酸和强结合的羧酸等含氧副产物。虽然甲酸在反应过程中稳定形成，但它很容易被臭氧进料氧化成CO2和CO。臭氧分解与苯氧化的比值约为9-10，且几乎不受反应温度和湿度的影响，表明在反应条件下，臭氧通过苯氧化被有效消耗。(C)2013 Elsevier Inc. All rights reserved.
This paper reports the catalytic behavior toward benzene oxidation in the presence of ozone of manganese oxides supported on a high Si/Al ratio zeolite (SiO2/Al2O3 = 180). The catalysts were characterized by N-2 adsorption, X-ray absorption fine structure (XAFS), and temperature-programmed reduction (TPR). By a conventional impregnation technique, the manganese oxides were highly dispersed in the zeolite Y in the 3+ oxidation state, and they were the active sites for benzene oxidation by ozone. Steady-state activities were obtained at 313-373 K under both dry and humid conditions. Under both of those conditions, a strong correlation was observed among the amounts of ozone consumed, benzene oxidized, and COx formed. Water vapor in the reaction gas enhanced benzene oxidation by promoting by-product compound oxidation by the catalyst, and water vapor thus slightly improved CO2 selectivity. Fourier-transformed infrared (FTIR) and temperature-programmed oxidation (TPO) studies demonstrated that benzene was oxidized on the catalysts to oxygen-containing by-products such as weakly bound formic acid and strongly bound carboxylates. Although formic acid was steadily formed during the reaction, it was readily oxidized to CO2 and CO by the ozone feed. The ratio of ozone decomposition to benzene oxidation was approximately 9-10 and was almost independent of reaction temperature and humidity, indicating that ozone was efficiently consumed through benzene oxidation under the reaction conditions. (C) 2013 Elsevier Inc. All rights reserved.