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沸石分子筛结构内配位不饱和位点:构筑与催化应用(英文) 被引量:5
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作者 李玮杰 孙兰兰 +3 位作者 谢林君 邓欣 关乃佳 李兰冬 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第9期1255-1281,共27页
具有规则微孔结构的沸石分子筛是目前广泛应用的吸附剂和催化剂,而它的框架结构还可作为承载配位不饱和位点的理想平台.近年来,沸石分子筛结构内配位不饱和位点的构建、表征和催化应用方面已经取得重要进展,本文将从配位催化的视角对其... 具有规则微孔结构的沸石分子筛是目前广泛应用的吸附剂和催化剂,而它的框架结构还可作为承载配位不饱和位点的理想平台.近年来,沸石分子筛结构内配位不饱和位点的构建、表征和催化应用方面已经取得重要进展,本文将从配位催化的视角对其进行总结与讨论.配位催化的概念由Natta在讨论Ziegler-Natta催化剂的性质时提出,已被广泛用于一系列重要反应,如加氢、氧化、羰基化、氢甲酰化和C-C键偶联中.配位催化尽管表现出高活性、高选择性和反应机理清晰等优点,但通常的过渡金属配合物催化剂在分离与回收方面也存在明显缺陷.沸石分子筛具有分子尺寸的规则孔道结构,其骨架、孔道内与离子交换位均可以引入过渡金属离子构筑配位不饱和位点.这一策略可以将配位化学与沸石化学的相关概念结合起来,并在多相催化反应过程中充分利用配位催化的优点.本文首先介绍了沸石分子筛骨架内与骨架外配位不饱和位点不同构筑策略,即离子交换-焙烧、扩散浸渍-焙烧、直接水热合成、过渡金属配合物封装以及骨架脱铝补位修饰,并对其特点进行了比较.随后讨论了用于检测阳离子落位、存在状态及其在沸石分子筛结构中动态变化的光谱技术,包括振动光谱(傅里叶变换红外光谱、拉曼光谱)、电子光谱(紫外-可见漫反射光谱、X射线光电子能谱)、共振波谱(固体核磁共振、电子自旋共振)以及X射线吸收谱(X射线近边吸收、X射线吸收精细结构).最后一部分总结了含配位不饱和位点的沸石分子筛在代表性重要催化反应中的应用,从氮氧化物转化、C-H键活化(甲烷羟基化、苯羟基化、丙烷氧化脱氢)、烯烃功能化(聚合、环氧化)、环氧化物开环(水合、氨解)和羰基活化(Baeyer-Villiger氧化重排、Meerwein-Ponndorf-Verley还原)等几类反应展开讨论.对反应机理与构效关系的认识一直以来是催化领域研究的挑战,而对于含配位不饱和位点的沸石分子筛这样复杂的体系来说更是如此.如果能够在沸石分子筛结构内构筑均一且结构明确的孤立金属离子位点,则可以将沸石分子筛骨架作为中心金属离子的配体,从而将含配位不饱和位点的沸石分子筛整体作为一类金属无机配合物,有助于更好地理解催化反应过程与本质. 展开更多
关键词 配位不饱和位点 沸石分子筛 构筑 表征 催化应用
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Optimizing zeolite stabilized Pt-Zn catalysts for propane dehydrogenation 被引量:7
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作者 linjun xie Yuchao Chai +4 位作者 Lanlan Sun Weili Dai Guangjun Wu Naijia Guan Landong Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第6期92-98,I0003,共8页
Propane dehydrogenation(PDH)provides an alternative route to non-petroleum based propylene and eligible catalysts with good overall performance are still being explored.Herein,we report the construction of zeolite sta... Propane dehydrogenation(PDH)provides an alternative route to non-petroleum based propylene and eligible catalysts with good overall performance are still being explored.Herein,we report the construction of zeolite stabilized Pt-Zn catalysts Pt-Zn/Si-Beta for PDH.Characterization results from transmission electron microscopy(TEM),ultraviolet-visible(UV-vis)and Fourier transform infrared(FTIR)spectroscopy reveal that highly-dispersed Zn species are stabilized by the silanols from zeolite framework dealumination,which then act as the anchoring sites for Pt species.The close contact between Pt-Zn species and the electronic interaction thereof make Pt-Zn/Si-Beta robust PDH catalysts.Under optimized conditions,a high propylene production rate of 4.11 molmol_(Pt)^(-1)s^(-1),high propylene selectivity of 98% and a sustainable deactivation rate of~0.02 h^(-1)can be simultaneously achieved at 823 K.Coke deposition is not the key reason for the catalytic deactivation,while the loss of Zn species and the resulting aggregation of Pt species under high temperatures are responsible for the irreversible deactivation of Pt-Zn/Si-Beta catalyst in PDH reaction. 展开更多
关键词 Propane dehydrogenation ZEOLITE Pt-Zn/Si-Beta DEACTIVATION
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Propane dehydrogenation catalyzed by in-situ partially reduced zinc cations confined in zeolites 被引量:4
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作者 linjun xie Rui Wang +3 位作者 Yuchao Chai Xuefei Weng Naijia Guan Landong Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第12期262-269,I0006,共9页
Propane dehydrogenation(PDH), employing Pt-or Cr-based catalysts, represents an emerging industrial route for propylene production. Due to the scarcity of platinum and the toxicity of chromium, alternative PDH catalys... Propane dehydrogenation(PDH), employing Pt-or Cr-based catalysts, represents an emerging industrial route for propylene production. Due to the scarcity of platinum and the toxicity of chromium, alternative PDH catalysts are being pursued. Herein, we report the construction of Zn-containing zeolite catalysts,namely Zn@S-1, for PDH reaction. Well-isolated zinc cations are successfully trapped and stabilized by the Si-OH groups in S-1 zeolites via in-situ hydrothermal synthesis. The as-prepared Zn@S-1 catalysts exhibit good dehydrogenation activity, high propylene selectivity, and regeneration capability in PDH reaction under employed conditions. The in-situ partial reduction of zinc species is observed and the partially reduced zinc cations are definitely identified as the active sites for PDH reaction. 展开更多
关键词 Propane dehydrogenation Zinc catalysts Zn@S-1 In-situ reduction
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Prevalence and associated factors of myocardial involvement in Duchenne muscular dystrophy patients in the first decade of life
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作者 Rong Xu Huayan Xu +13 位作者 Kun Zhang Hong Xu Hui Liu Hang Fu linjun xie Ke Xu Chuan Fu Xuesheng Li Xiaoyue Zhou Rajiv Ananthakrishna Joseph BSelvanayagam Li Yu Xiaotang Cai Yingkun Guo 《Chinese Medical Journal》 SCIE CAS CSCD 2023年第9期1132-1134,共3页
To the Editor:Duchenne muscular dystrophy(DMD)is a rare X-linked inherited disorder caused by dystrophin deficiency,which results in sarcolemmal fragility and degeneration of skeletal and cardiac myocytes.[1]Cardiac i... To the Editor:Duchenne muscular dystrophy(DMD)is a rare X-linked inherited disorder caused by dystrophin deficiency,which results in sarcolemmal fragility and degeneration of skeletal and cardiac myocytes.[1]Cardiac involvement ismanifested asDMDcardiomyopathy,which is the leading cause of disease-related morbidity and mortality among DMD patients. 展开更多
关键词 INVOLVEMENT PATIENTS DYSTROPHY
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