Distribution and role of Li in Li-doped MgO catalysts for oxidative coupling of methane

• Published in: Journal of catalysis 2017-02, Vol.346, p.57-61
• Main Authors: Luo, Liangfeng, Jin, Yuekang, Pan, Haibin, Zheng, Xusheng, Wu, Lihui, You, Rui, Huang, Weixin
• Format: Article
• Language: English
• Subjects: Desorption; Migration; Structure–activity relation; Surface composition; Synchrotron radiation photoelectron spectroscopy
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2016.11.034

[Display omitted] •Initial Li content of Li/MgO affects the surface distribution of Li during the OCM reaction.•Li surface distribution in Li/MgO with large initial Li content maintains migration and desorption processes of Li.•Migration and desorption processes of Li form MgO surfaces with microstructures active in the OCM reaction.•Li in Li/MgO catalysts acts as a structural modifier instead of an active center. Surface distributions of Li in two Li/MgO catalysts with similar Li content but different microstructures and catalytic performance in the OCM reaction were characterized by synchrotron radiation photoelectron spectroscopy. Both Li/MgO catalysts show similar Li content within the topmost surface region, while the Li/MgO catalyst with a Li surface distribution capable of maintaining the migration and desorption processes of Li during the OCM reaction exhibits MgO surfaces with microstructures active in the OCM reaction. These results demonstrate that Li in Li/MgO catalysts acts as a structural modifier of the active MgO component rather than as an active center.