Jia-yu ZHANG , Na SUN , Li-xia LING , Ri-guang ZHANG , Li-tao JIA , De-bao LI , Bao-jun WANG
{"title":"Effect of different valence metals doping on methane activation over La2O3(001) surface","authors":"Jia-yu ZHANG , Na SUN , Li-xia LING , Ri-guang ZHANG , Li-tao JIA , De-bao LI , Bao-jun WANG","doi":"10.1016/S1872-5813(23)60343-3","DOIUrl":null,"url":null,"abstract":"<div><p>La<sub>2</sub>O<sub>3</sub> as a catalyst is used for oxidative coupling of methane (OCM) reactions due to its excellent stability and high C<sub>2</sub> selectivity, but poor activity on methane dissociation limits its wide application. Different valence metals are doped on the La<sub>2</sub>O<sub>3</sub>(001) surface to improve the methane conversion activity, and the activation of methane on metal-doped La<sub>2</sub>O<sub>3</sub>(001) surfaces has been investigated via the density functional theory (DFT) calculations. The relationship between the valence states of doped metals and the methane conversion activities shows that doping low valence metals (Li, Na, K, Mg, Ca, Sr and Ba) and equivalent metals (Al, Ga, In) can significantly improve the conversion activity of methane. Among them, the activation energy of methane on the Li-La<sub>2</sub>O<sub>3</sub>(001) surface is the lowest, which is only 13.0 kJ/mol. However, doping of high valence metals (Zr, Nb, Re and W) cannot improve the CH<sub>4</sub> dissociation activity. Furthermore, the relationships between surface oxygen vacancy formation energies, acid-base properties and the activation energies of CH<sub>4</sub> have also been investigated. The results show that with the increase of metal valence state, the oxygen vacancy formation energy increases, while the dissociation activity of CH<sub>4</sub> decreases. The introduction of alkali and alkaline earth metals increases the alkalinity of La<sub>2</sub>O<sub>3</sub>(001) surface, and the alkalinity of La<sub>2</sub>O<sub>3</sub>(001) doped with the alkali metal is stronger than that with the alkaline earth metal, exhibiting higher dissociation activity of CH<sub>4</sub>. Our research may provide a guide for improving methane conversion activity on La<sub>2</sub>O<sub>3</sub> catalysts.</p></div>","PeriodicalId":15956,"journal":{"name":"燃料化学学报","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"燃料化学学报","FirstCategoryId":"1087","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1872581323603433","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"Energy","Score":null,"Total":0}
引用次数: 2
Abstract
La2O3 as a catalyst is used for oxidative coupling of methane (OCM) reactions due to its excellent stability and high C2 selectivity, but poor activity on methane dissociation limits its wide application. Different valence metals are doped on the La2O3(001) surface to improve the methane conversion activity, and the activation of methane on metal-doped La2O3(001) surfaces has been investigated via the density functional theory (DFT) calculations. The relationship between the valence states of doped metals and the methane conversion activities shows that doping low valence metals (Li, Na, K, Mg, Ca, Sr and Ba) and equivalent metals (Al, Ga, In) can significantly improve the conversion activity of methane. Among them, the activation energy of methane on the Li-La2O3(001) surface is the lowest, which is only 13.0 kJ/mol. However, doping of high valence metals (Zr, Nb, Re and W) cannot improve the CH4 dissociation activity. Furthermore, the relationships between surface oxygen vacancy formation energies, acid-base properties and the activation energies of CH4 have also been investigated. The results show that with the increase of metal valence state, the oxygen vacancy formation energy increases, while the dissociation activity of CH4 decreases. The introduction of alkali and alkaline earth metals increases the alkalinity of La2O3(001) surface, and the alkalinity of La2O3(001) doped with the alkali metal is stronger than that with the alkaline earth metal, exhibiting higher dissociation activity of CH4. Our research may provide a guide for improving methane conversion activity on La2O3 catalysts.
期刊介绍:
Journal of Fuel Chemistry and Technology (Ranliao Huaxue Xuebao) is a Chinese Academy of Sciences(CAS) journal started in 1956, sponsored by the Chinese Chemical Society and the Institute of Coal Chemistry, Chinese Academy of Sciences(CAS). The journal is published bimonthly by Science Press in China and widely distributed in about 20 countries. Journal of Fuel Chemistry and Technology publishes reports of both basic and applied research in the chemistry and chemical engineering of many energy sources, including that involved in the nature, processing and utilization of coal, petroleum, oil shale, natural gas, biomass and synfuels, as well as related subjects of increasing interest such as C1 chemistry, pollutions control and new catalytic materials. Types of publications include original research articles, short communications, research notes and reviews. Both domestic and international contributors are welcome. Manuscripts written in Chinese or English will be accepted. Additional English titles, abstracts and key words should be included in Chinese manuscripts. All manuscripts are subject to critical review by the editorial committee, which is composed of about 10 foreign and 50 Chinese experts in fuel science. Journal of Fuel Chemistry and Technology has been a source of primary research work in fuel chemistry as a Chinese core scientific periodical.