文献类型：期刊文献

英文题名：Strategies To Improve the Activity While Maintaining the Selectivity of Oxidative Coupling of Methane at La2O3: A Density Functional Theory Study

作者：Wang, Zhi-Qiang[1,2];Wang, Dong[1,2];Gong, Xue-Qing[1,2]

机构：[1]East China Univ Sci & Technol, Ctr Computat Chem, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Res Inst Ind Catalysis, Sch Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China

年份：2020

卷号：10

期号：1

起止页码：586

外文期刊名：ACS CATALYSIS

收录：;EI(收录号：20200107951706);WOS:【SCI-EXPANDED(收录号:WOS:000506725100064)】；

基金：The authors thank the National Super Computing Center in Jinan for computing time. This work was supported by National Key R&D Program of China (2018YFA0208602), National Natural Science Foundation of China (21825301, 21573067, 21421004), and the Program of Shanghai Academic Research Leader (17XD1401400).

语种：英文

外文关键词：oxidative coupling of methane; rare earth oxides; doped La2O3(001); activity and selectivity; density functional theory

摘要：Oxidative coupling of methane (OCM) holds the promise to achieve high-value-added products directly from methane, and the strategies to improve the catalytic performance of this process are highly desired. In this work, we performed extensive density functional theory (DFT) calculations to systematically study the activity and selectivity of the OCM reactions on several types of the La2O3 and CeO2 catalysts. We theoretically evidenced that the La2O3 catalyst has high hydrocarbon selectivity but low activity, while the CeO2 shows an opposite performance. These results can be largely rationalized by the calculated reaction energetics in generating the key CH3 center dot intermediates and further protecting them from excessive oxidation on the surface. We then proposed two strategies to improve the OCM activity while maintaining the selectivity of the La2O3 catalyst. Geometrically, by constructing the stepped La2O3(210) surface exposing lattice oxygens with low coordination numbers, both the heterolytic cleavage of the C-H bond in methane and the occurrence of the key CH3 center dot intermediates could be promoted. Electronically, codoping of Sr and Ce into La2O3 could favor the direct formation of CH3 center dot and further avoid its deactivation on the surface, leading to the significantly improved OCM performance. By conducting further analyses on the thermostability of the catalysts and calculating catalytic energetics of the complete reaction cycle, we excluded the practical application of the high-Miner-index La2O3 surfaces, but we theoretically predicted the Sr/Ce-La2O3 catalyst with a proper doping concentration to be highly efficient for catalyzing the OCM reactions.