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Ab initio molecular dynamics simulation reveals the influence of entropy effect on Co@BEA zeolite-catalyzed dehydrogenation of ethane
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作者 Yumeng Fo Shaojia Song +8 位作者 Kun Yang Xiangyang Ji Luyuan Yang Liusai Huang Xinyu Chen Xueqiu Wu Jian Liu Zhen Zhao Weiyu Song 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第10期195-205,共11页
The C–H bond activation in alkane dehydrogenation reactions is a key step in determining the reaction rate.To understand the impact of entropy,we performed ab initio static and molecular dynamics free energy simulati... The C–H bond activation in alkane dehydrogenation reactions is a key step in determining the reaction rate.To understand the impact of entropy,we performed ab initio static and molecular dynamics free energy simulations of ethane dehydrogenation over Co@BEA zeolite at different temperatures.AIMD simulations showed that a sharp decrease in free energy barrier as temperature increased.Our analysis of the temperature dependence of activation free energies uncovered an unusual entropic effect accompanying the reaction.The unique spatial structures around the Co active site at different temperatures influenced both the extent of charge transfer in the transition state and the arrangement of 3d orbital energy levels.We provided explanations consistent with the principles of thermodynamics and statistical physics.The insights gained at the atomic level have offered a fresh interpretation of the intricate long-range interplay between local chemical reactions and extensive chemical environments. 展开更多
关键词 Ethane dehydrogenation c-h bond activation Ab initio molecular dynamics simulation ENTROPY heterogeneous catalysis
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C-H bond activation of propane on Ga_(2)O_(2)^(2+) in Ga/H-ZSM-5 and its mechanistic implications
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作者 Zhaoqi Zhao Yunzhu Zhong +1 位作者 Xiaoxia Chang Bingjun Xu 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第9期32-43,共12页
Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified ... Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga_(2)O_(2)^(2+) species corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga_(2)O_(2)^(2+) species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga_(2)O_(2)^(2+) species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga_(2)O_(2)^(2+) species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga_(2)O_(2)^(2+) species corresponding to GaHHW. 展开更多
关键词 Propane dehydrogenation Ga_(2)O_(2)^(2+) Activation of c-h bond Ga species
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Oxidative co-dehydrogenation of ethane and propane over h-BN as an effective means for C-H bond activation and mechanistic investigations 被引量:4
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作者 Hao Tian Bingjun Xu 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第8期2173-2182,共10页
Hexagonal boron nitride(h-BN)is a highly selective catalyst for oxidative dehydrogenation of light alkanes to produce the corresponding alkenes.Despite intense recent research effort,many aspects of the reaction mecha... Hexagonal boron nitride(h-BN)is a highly selective catalyst for oxidative dehydrogenation of light alkanes to produce the corresponding alkenes.Despite intense recent research effort,many aspects of the reaction mechanism,such as the observed supra-linear reaction order of alkanes,remain unresolved.In this work,we show that the introduction of a low concentration of propane in the feed of ethane oxidative dehydrogenation is able to enhance the C_(2)H_(6) conversion by 47%,indicating a shared reaction intermediate in the activation of ethane and propane.The higher activity of propane makes it the dominant radical generator in the oxidative co-dehydrogenation of ethane and propane(ODEP).This unique feature of the ODEP renders propane an effective probe molecule to deconvolute the two roles of alkanes in the dehydrogenation chemistry,i.e.,radical generator and substrate.Kinetic studies indicate that both the radical generation and the dehydrogenation pathways exhibit a first order kinetics toward the alkane partial pressure,leading to the observed second order kinetics of the overall oxidative dehydrogenation rate.With the steady-state approximation,a radical chain reaction mechanism capable of rationalizing observed reaction behaviors is proposed based on these insights.This work demonstrates the potential of ODEP as a strategy of both activating light alkanes in oxidative dehydrogenation on BN and mechanistic investigations. 展开更多
关键词 hexagonal boron nitride Oxidative dehydrogenation Radical chain reaction Reaction order c-h activation
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Activity and selectivity of propane oxidative dehydrogenation over VO_3/CeO_2(111) catalysts: A density functional theory study 被引量:3
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作者 Chang Huang Zhi-Qiang Wang Xue-Qing Gong 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第9期1520-1526,共7页
The oxidative dehydrogenation(ODH) of propane on monomeric VO3 supported by CeO2(111)(VO3/CeO 2(111)) is studied by periodic density functional theory calculations. Detailed energetic, structural, and electron... The oxidative dehydrogenation(ODH) of propane on monomeric VO3 supported by CeO2(111)(VO3/CeO 2(111)) is studied by periodic density functional theory calculations. Detailed energetic, structural, and electronic properties of these reactions are determined. The calculated activation energies of the breaking of the first and second C–H bonds of propane on the VO3/CeO2(111) catalyst are compared, and it is found that both the unique structural and electronic effects of the VO3/CeO2(111) catalyst contribute to the relatively easy rupture of the first C–H bond of the propane molecule during the ODH reaction. In particular, the so-called new empty localized states that are mainly constituted of O2 porbitals of the ceria-supported VO3 species are determined to be crucial for assisting the cleavage of the first C–H bond of the propane molecule. Following this they become occupied and the remaining C–H bonds become increasingly difficult to break owing to the increasing repulsion between the localized 4 felectrons at the Cecations, resulting in the adsorption of more H and other moieties. This work illustrates that CeO2-supported monomeric vanadium oxides can exhibit unique activity and selectivity for the catalytic ODH of alkanes to alkenes. 展开更多
关键词 Oxidativede hydrogenation Propanetopropylene chbondcleavage ceria‐support edvanadia Density functional theorycal culations
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Mn-corrolazine-based 2D-nanocatalytic material with single Mn atoms for catalytic oxidation of alkane to alcohol 被引量:2
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作者 Chun Zhu Jin-Xia Liang +2 位作者 Yang Meng Jian Lin Zexing Cao 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第6期1030-1039,共10页
Heterogenization of organic-macrocyclic metal catalysts is one of the simplest and most efficient methods for effective separation of products and cyclic application of a catalyst.By using an environmentally friendly ... Heterogenization of organic-macrocyclic metal catalysts is one of the simplest and most efficient methods for effective separation of products and cyclic application of a catalyst.By using an environmentally friendly Mn-corrolazine catalyst as the building unit,which can directly oxidize organic substrates under oxygen atmosphere and mild conditions,we theoretically constructed a novel two-dimensional(2D)Mn-corrolazine nanocatalytic material with high catalytic activity.In this material,each Mn atom maintains its electronic configuration in the monomer and can directly activate O2 as the single-atom catalyst(SAC)center to form a radical-like[Mn]-O-O under mild visible-light irradiation conditions.The newly generated[Mn]–O–O can efficiently and selectively oxidize C–H bonds to form alcohol species through H-abstraction and the rebound reaction.Moreover,the catalytic reaction is easily regulated by an external electric field along its intrinsic Mn–O–O reaction axis.The current study provides a theoretical foundation for further experimental studies and practical applications of the Mn-corrolazine-based SAC. 展开更多
关键词 Single-atom catalyst hETEROGENIZATION Two-dimensional nanomaterials First-principles calculations ch bond activation
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A Mechanistic Switch in C-H Bond Activation by Elusive Fe^(V)(O)(TAML)Reaction Intermediate:A Theoretical Study 被引量:1
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作者 Anran Zhou Zhiqiang Fu +2 位作者 Xuanyu Cao Yufen Zhao Yong Wang 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第2期383-389,I0032-I0064,I0004,共41页
The divergent behavior of C-H bond oxidations of aliphatic substrates compared to those of aromatic substrates shown in Gupta’s experiment was mechanistically studied herein by means of density functional theory calc... The divergent behavior of C-H bond oxidations of aliphatic substrates compared to those of aromatic substrates shown in Gupta’s experiment was mechanistically studied herein by means of density functional theory calculations.Our calculations reveal that such difference is caused by different reaction mechanisms between two kinds of substrates(the aliphatic cyclohexane,2,3-dimethylbutane and the aromatic toluene,ethylbenzene and cumene).For the aliphatic substrates,C-H oxidation by the oxidant Fe^(V)(O)(TAML)is a hydrogen atom transfer process;whereas for the aromatic substrates,C-H oxidation is a proton-coupled electron transfer(PCET)process with a proton transfer character on the transition state,that is,a proton-coupled electron transfer process holding a proton transfer-like transition state(PCET(PT)).This difference is caused by the strongπ-πinteractions between the tetra-anionic TAML ring and the phenyl ring of the aromatic substrates,which has a“pull”effect to make the electron transfer from substrates to the Fe=O moiety inefficient. 展开更多
关键词 c-h bond activation hydrogen atom transfer Proton coupled electron transfer Density functional theory
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室温光驱动甲烷活化 被引量:1
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作者 母晓玥 李路 《物理化学学报》 SCIE CAS CSCD 北大核心 2019年第9期968-976,共9页
如何在较温和的条件下将甲烷转化为其它更有价值的有机衍生物,如醇、芳烃、长链烷烃和烯烃等,长期以来是催化、化学及化工领域的热点课题和难点课题之一。为了提高甲烷的转化效率,过去几十年里,研究人员不断开发新的催化剂和新的反应路... 如何在较温和的条件下将甲烷转化为其它更有价值的有机衍生物,如醇、芳烃、长链烷烃和烯烃等,长期以来是催化、化学及化工领域的热点课题和难点课题之一。为了提高甲烷的转化效率,过去几十年里,研究人员不断开发新的催化剂和新的反应路径。与传统高温热催化方法相比,如果能利用自然界中丰富的太阳能驱动甲烷转化,将同时满足能源和环保两方面的要求,是各种新型非常规策略中比较令人期待的一种。本文从光催化材料的组成、结构及催化路线、催化机制等方面进行总结,对当前室温光活化甲烷分子的研究现状加以论述。 展开更多
关键词 甲烷转化 c―h键活化 光催化 无氧脱氢 分子筛 半导体
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催化在有机合成中的新进展 被引量:1
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作者 彭秀琴 《河北化工》 2011年第6期44-45,共2页
近年来,过渡金属催化的卤代芳烃与各种亲核试剂的偶联反应已成为构筑C―C或C―杂原子键的有效手段,例如著名的Suzuki、Kumada、Stille、Negishi等生成C―C键的偶联反应等。最近,C―H键的直接活化及功能化方面有了一些突破。介绍了这一... 近年来,过渡金属催化的卤代芳烃与各种亲核试剂的偶联反应已成为构筑C―C或C―杂原子键的有效手段,例如著名的Suzuki、Kumada、Stille、Negishi等生成C―C键的偶联反应等。最近,C―H键的直接活化及功能化方面有了一些突破。介绍了这一领域的新进展。 展开更多
关键词 c―h键活化 过渡金属 催化 有机合成
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甲烷/甲醇光催化转化研究进展 被引量:3
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作者 张舒怡 鲍静娴 +2 位作者 吴博 钟良枢 孙予罕 《物理化学学报》 SCIE CAS CSCD 北大核心 2019年第9期923-939,共17页
在能源需求不断上涨及石油供应日益紧张的背景下,开展对煤、天然气或生物质等非油基资源(CO、CO2、CH3OH、CH4等)的高效利用显得尤为重要。C1小分子(CO、CO2、CH3OH、CH4等)经催化转化可得到燃料及多种化学品,一直受到学术界及工业界的... 在能源需求不断上涨及石油供应日益紧张的背景下,开展对煤、天然气或生物质等非油基资源(CO、CO2、CH3OH、CH4等)的高效利用显得尤为重要。C1小分子(CO、CO2、CH3OH、CH4等)经催化转化可得到燃料及多种化学品,一直受到学术界及工业界的广泛关注。甲烷/甲醇作为重要的C1平台分子,其催化转化在C1化学中占据重要地位。为了提高目标产物的选择性,需要有效地控制甲烷/甲醇中C―H键的活化。传统热催化作为甲烷/甲醇最常见的转化方法发展已久,但仍然面临着反应条件苛刻、能耗大、产率和选择性低等问题。光催化反应通过引入光能弥补反应中吉布斯自由能的上升,同时具有反应条件温和、操作简单、能耗低等特点,从而为甲烷/甲醇转化提供了新的途径。通过调节光的波长、强度以及催化剂的氧化能力可以实现甲烷/甲醇的选择性转化,减少副产物的生成。此外,光催化能够选择性活化甲醇的C―H键而非O―H键,从而实现甲醇的C―C偶联反应。本文主要围绕甲烷/甲醇的重整、氧化和偶联反应,总结近年来的光催化转化进展,并对进一步提高光催化性能做了展望。 展开更多
关键词 c―h键活化 c1化学 甲烷 甲醇 光催化
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C–H bond activation in the total syntheses of natural products 被引量:2
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作者 Pengyu Tao Yanxing Jia 《Science China Chemistry》 SCIE EI CAS CSCD 2016年第9期1109-1125,共17页
The transition metal-mediated C–H bond activation has emerged as a powerful and ideal method for the total syntheses of natural products and pharmaceuticals, and has had a significant impact on synthetic planning and... The transition metal-mediated C–H bond activation has emerged as a powerful and ideal method for the total syntheses of natural products and pharmaceuticals, and has had a significant impact on synthetic planning and strategy in complex natural products.In this review, we describe selected recent examples of the transition metal-mediated C–H bond activation strategies for the rapid syntheses of natural products. 展开更多
关键词 c-h activation transition metal natural product total synthesis
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Photoinduced C–H direct arylation of unactivated arenes
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作者 Jian Kan Shijun Huang +2 位作者 Huaiqing Zhao Jin Lin Weiping Su 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第8期1329-1333,共5页
Two general protocols have been developed for the photoinduced, metal-free direct arylation of unactivated arenes with aryl iodide. Both methods gave good to excellent yields for most substrates. Notably, the C-F bond... Two general protocols have been developed for the photoinduced, metal-free direct arylation of unactivated arenes with aryl iodide. Both methods gave good to excellent yields for most substrates. Notably, the C-F bond in method A and the C-F, C-C1 and C-Br bonds in method B could survive the arylation reaction. These methods offered excellent options for syntheses of biaryls. 展开更多
关键词 c-h bond activation PhOTOINDUcED free radical aryl iodide
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Palladium-catalyzed R_2(O)P-directed C(sp^2)–H activation
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作者 Hongyu Zhang Shangdong Yang 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第8期1280-1285,共6页
In recent years,transition-metal-catalyzed inert C–H bond activation has developed rapidly and is a powerful protocol for the construction of new C–C or C–X bonds and the introduction of new functional groups.Our g... In recent years,transition-metal-catalyzed inert C–H bond activation has developed rapidly and is a powerful protocol for the construction of new C–C or C–X bonds and the introduction of new functional groups.Our group has also developed a series of R2(O)P-directed Pd-catalyzed C–H functionalizations involving olefination,hydroxylation,acetoxylation,arylation,and acylation through an uncommon seven-membered cyclo-palladium pretransition state.Unlike previously used directing groups,the R2(O)P group acts as a directing group and is also involved in the construction of P,-hetero-ligands. 展开更多
关键词 c-h bond activation PD-cATALYZED R2(O)P-directed
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