期刊
JOURNAL OF CATALYSIS
卷 408, 期 -, 页码 465-477出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2021.04.007
关键词
Layered Sr (n+1) SnnO (3n+1) perovskites; Oxidative coupling of methane; Ruddlesden-Popper phase structure; Phase dependent of reactivity; Active electrophilic/lattice oxygen and basic sites
资金
- National Natural Science Foundation of China [21962009, 22062013, 21666020, 21567016]
- National Key Research and Development Program of China [2016YFC0209302]
- Natural Science Foundation of Jiangxi Province [20202BAB203006, 20181ACB20005]
- Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis [20181BCD40004]
By designing and synthesizing SrSnO3, Sr2SnO4, and Sr3Sn2O7 perovskite compounds, it is found that small crystal structure changes significantly influence the reaction performance of the catalysts. The electrophilic chemisorbed substances and surface lattice substances on these perovskite catalysts actively and selectively contribute to C-2 product formation, and the moderate and strong surface basic sites play a vital role in the reaction.
To seek more feasible catalysts for OCM reaction, SrSnO3, Sr2SnO4 and Sr3Sn2O7 perovskite compounds have been purposely designed and synthesized. It is discovered that the fine crystal structure change influences the reaction performance of the catalysts significantly, which follows the order of Sr2SnO4 > Sr3Sn2O7 > SrSnO3. On these perovskite catalysts, both the electrophilic chemisorbed O-2(-)/O-2(2-) and surface lattice O2- species are active and selective for C-2 product formation. In addition, both of their moderate and strong surface basic sites contribute vitally to the reaction. It is found that the moderate sites are associated with the M+ -O- ion pairs and oxygen vacancy, and the strong basic sites are related to the coordinatively unsaturated surface lattice O2-. Due to the phase structure difference of the three perovskites, their Sn-O bond length changes in the order of Sr2SnO4 > Sr3Sn2O7 > SrSnO3. Furthermore, both the electrical conductivity and DFT calculation results have testified that it is easier for Sr2SnO4 to generate surface oxygen vacancies than Sr3Sn2O7 and SrSnO3, which explains that this sample has the largest quantities of active surface oxygen and basic sites, as well as the best OCM performance. (c) 2021 Elsevier Inc. All rights reserved.
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