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论文类型：期刊论文
发表时间：2019-12-01
发表刊物：JOURNAL OF CATALYSIS
收录刊物：SCIE、EI
卷号：380
页面范围：21-31
ISSN号：0021-9517
关键字：MnOx/SBA-15; Oxygen species; Redox reaction; Isotopically labeled oxygen; Interface
摘要：An investigation of the effect of oxygen and silver species on the oxidation of toluene has been launched to identify the reaction process and mechanism over MnOx/SBA-15 and Ag-MnOx/SBA-15 catalysts. Detailed knowledge of the effect and cycle of oxygen species under reaction is typically missing, and this study points at the behavior of oxygen species over MnOx/SBA-15 for toluene oxidation for the first time, using in situ mass spectrum techniques with the isotope O-18(2). It is found that the Langmuir-Hinshelwood and Mars-van Krevelen mechanism coexist in toluene oxidation over MnOx/SBA-15 catalyst. In this study, surface and bulk lattice oxygen are shown to be vital active oxygen species in the whole reaction. The consumed oxygen species are replenished with gaseous oxygen, and the process follows the Mars-van Krevelen mechanism, as confirmed by detection of isotopic products. The adsorbed oxygen species with good mobility is also found to start up and participate in the reaction at lower temperatures, which follows the Langmuir-Hinshelwood reaction mechanism. The addition of Ag increases the amount of surface lattice oxygen species and improves the transformation rate and the migration of lattice oxygen, which effectively facilitates the low-temperature activity of toluene oxidation. (C) 2019 Elsevier Inc. All rights reserved.