气候变化领域集成服务门户(CCPortal): “Soft” oxidative coupling of methane to ethylene: Mechanistic insights from combined experiment and theory

CCPortal

DOI	10.1073/pnas.2012666118
	“Soft” oxidative coupling of methane to ethylene: Mechanistic insights from combined experiment and theory
	Liu S.; Udyavara S.; Zhang C.; Peter M.; Lohr T.L.; Dravid V.P.; Neurock M.; Marks T.J.
发表日期	2021
ISSN	0027-8424
卷号	118 期号:23
英文摘要	The oxidative coupling of methane to ethylene using gaseous disulfur (2CH4 + S2 → C2H4 + 2H2S) as an oxidant (SOCM) proceeds with promising selectivity. Here, we report detailed experimental and theoretical studies that examine the mechanism for the conversion of CH4 to C2H4 over an Fe3O4-derived FeS2 catalyst achieving a promising ethylene selectivity of 33%. We compare and contrast these results with those for the highly exothermic oxidative coupling of methane (OCM) using O2 (2CH4 + O2 → C2H4 + 2H2O). SOCM kinetic/mechanistic analysis, along with density functional theory results, indicate that ethylene is produced as a primary product of methane activation, proceeding predominantly via CH2 coupling over dimeric S-S moieties that bridge Fe surface sites, and to a lesser degree, on heavily sulfided mononuclear sites. In contrast to and unlike OCM, the overoxidized CS2 by-product forms predominantly via CH4 oxidation, rather than from C2 products, through a series of C-H activation and S-addition steps at adsorbed sulfur sites on the FeS2 surface. The experimental rates for methane conversion are first order in both CH4 and S2, consistent with the involvement of two S sites in the rate-determining methane C-H activation step, with a CD4/CH4 kinetic isotope effect of 1.78. The experimental apparent activation energy for methane conversion is 66 ± 8 kJ/mol, significantly lower than for CH4 oxidative coupling with O2. The computed methane activation barrier, rate orders, and kinetic isotope values are consistent with experiment. All evidence indicates that SOCM proceeds via a very different pathway than that of OCM. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Catalysis; Kinetics and density functional theory (DFT); Reaction mechanism; Sulfur oxidative coupling of methane (SOCM)
语种	英语
scopus关键词	carbene; carbon; carbon disulfide; ethylene; iron oxide; methane; oxidizing agent; oxygen; sulfur; adsorption; Article; catalyst; chemical reaction kinetics; controlled study; dehydrogenation; density functional theory; desorption; energy transfer; experimental study; hydrogen bond; kinetic isotope effect; kinetics; oxidative coupling; reaction analysis; theoretical study
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/238531
作者单位	Department of Chemistry, Northwestern University, Evanston, IL 60208, United States; Center for Catalysis and Surface Science, Northwestern University, Evanston, IL 60208, United States; Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, United States; Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, United States; Materials Research Center, Northwestern University, Evanston, IL 60208, United States
推荐引用方式 GB/T 7714	Liu S.,Udyavara S.,Zhang C.,等. “Soft” oxidative coupling of methane to ethylene: Mechanistic insights from combined experiment and theory[J],2021,118(23).
APA	Liu S..,Udyavara S..,Zhang C..,Peter M..,Lohr T.L..,...&Marks T.J..(2021).“Soft” oxidative coupling of methane to ethylene: Mechanistic insights from combined experiment and theory.Proceedings of the National Academy of Sciences of the United States of America,118(23).
MLA	Liu S.,et al."“Soft” oxidative coupling of methane to ethylene: Mechanistic insights from combined experiment and theory".Proceedings of the National Academy of Sciences of the United States of America 118.23(2021).