甲烷在单原子合金催化剂上选择性氧化制甲醇的理论研究  

Theoretical insights into the selective oxidation of methane to methanol on single-atom alloy catalysts

作　　者：周磊 苏亚琼 胡同亮 Lei Zhou;Ya-Qiong Su;Tong-Liang Hu(School of Materials Science and Engineering,National Institute for Advanced Materials,Nankai University,Tianjin 300350,China;School of Chemistry,Xi’an Key Laboratory of Sustainable Energy Materials Chemistry,State Key Laboratory of Electrical Insulation and Power Equipment,Engineering Research Center of Energy Storage Materials and Devices of Ministry of Education,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]School of Materials Science and Engineering,National Institute for Advanced Materials,Nankai University,Tianjin 300350,China [2]School of Chemistry,Xi’an Key Laboratory of Sustainable Energy Materials Chemistry,State Key Laboratory of Electrical Insulation and Power Equipment,Engineering Research Center of Energy Storage Materials and Devices of Ministry of Education,Xi’an Jiaotong University,Xi’an 710049,China

出　　处：《Science China Materials》2023年第8期3189-3199,共11页中国科学（材料科学（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (22275102);the Natural Science Foundation of Tianjin (20JCYBJC01330);Haihe Laboratory of Sustainable Chemical Transformations;the "Young Talent Support Plan" of Xi’an Jiaotong University

摘　　要：将甲烷直接转化为燃料和高附加值化学品引起了越来越多的研究兴趣,然而由于甲烷的化学惰性,实现这一过程仍然是一个巨大的挑战.本文设计了12种单原子合金催化剂(SAAs)应用于甲烷的活化,利用密度泛函理论(DFT)计算和微观动力学模拟筛选出对甲烷C–H键解离具有优异催化活性的单原子合金,并在此基础上进一步研究了甲烷选择性氧化制甲醇的机理.计算结果表明,惰性金属Ag、Au和Cu基底中掺杂Ir单原子具有更高的甲烷解离活性,这主要源于甲烷C–H键与Ir原子投影d轨道之间的相互作用.在引入分子氧之后,我们提出了甲烷选择性氧化制甲醇的三种反应机理.通过DFT计算确定了3条途径的完整反应网络,同时微观动力学模拟揭示了实际反应条件下每种SAA表面上反应物种覆盖度的变化.表面覆盖度分析表明,在所有的温度范围内,Ir1/Ag表面都有利于氧化反应,而Ir1/Au和Ir1/Cu只在有限的温度区间内有利于该氧化过程,表明Ir1/Ag单原子合金是甲烷选择性氧化制甲醇反应中非常有效的单原子合金催化剂.The direct conversion of methane into valueadded fuels and chemicals such as methanol has attracted increasing interest,but remains a great challenge due to the chemical inertness of methane.Herein,twelve single-atom alloys(SAAs)were designed for the activation of methane initially,and then the ones owning superior catalytic activity for C–H bond dissociation were screened out for further investigation of selective oxidation of methane to methanol by using density functional theory(DFT)calculations and microkinetic modeling.The results indicate that doping of Ir metal-atom into inert coinage hosts(Ag,Au and Cu)leads to a higher activity for methane dissociation,primarily deriving from the interaction between the C–H bond of methane and the unique projected d-band density of states of the Ir atom.With the introduction of molecular oxygen,three possible reaction mechanisms for selective oxidation of methane to methanol were proposed.Through DFT calculations,the complete reaction networks of three pathways were determined,and microkinetics revealed the changes of surface coverage of reactive species on each SAA under actual reaction conditions.The sophisticated analysis showed oxidation reactions were in favor on Ir1/Ag surface over all temperature ranges while favorable for Ir1/Au and Ir1/Cu within a limited interval,indicating that Ir1/Ag SAA is the most efficient for selective oxidation of methane to methanol.The insights in this work provide important guidelines for the design of highly active and efficient catalysts for direct conversion of methane in future.

关 键 词：微观动力学 单原子 选择性氧化 合金催化剂 化学惰性 氧化过程 氧化反应 DFT计算 

分 类 号：TQ223.121[化学工程—有机化工] TQ426