共查询到20条相似文献,搜索用时 15 毫秒
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Jooyoung Chung Chanhoi Kim Hansaem Jeong Prof. Taekyung Yu Do Huy Binh Prof. Jyongsik Jang Prof. Jaichan Lee Prof. B. Moon Kim Prof. Byungkwon Lim 《化学:亚洲杂志》2013,8(5):919-925
A systematic study on the selective semihydrogenation of alkynes to alkenes on shape‐controlled palladium (Pd) nanocrystals was performed. Pd nanocrystals with a cubic shape and thus exposed {100} facets were synthesized in an aqueous solution through the reduction of Na2PdCl4 with L ‐ascorbic acid in the presence of bromide ions. The Pd nanocubes were tested as catalysts for the semihydrogenation of various alkynes such as 5‐decyne, 2‐butyne‐1,4‐diol, and phenylacetylene. For all substrates, the Pd nanocubes exhibited higher alkene selectivity (>90 %) than a commercial Pd/C catalyst (75–90 %), which was attributed to a large adsorption energy of the carbon–carbon triple bond on the {100} facets of the Pd nanocubes. Our approach based on the shape control of Pd nanocrystals offers a simple and effective route to the development of a highly selective catalyst for alkyne semihydrogenation. 相似文献
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Minkee Choi Dong‐Hwan Lee Kyungsu Na Byung‐Woo Yu Ryong Ryoo Prof. 《Angewandte Chemie (International ed. in English)》2009,48(20):3673-3676
Exchange for the better : Mesoporous sodalite and NaA zeolite exchanged with Pd2+ exhibit remarkably high activity and reusability in C? C coupling reactions under aerobic atmosphere. It is proposed that the catalytic reactions are mediated by a molecular Pd0 species generated in situ within the pores (see picture), which is oxidized back to Pd2+ by O2, preventing the formation of catalytically inactive Pd0 agglomerates.
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Oxygen‐Assisted Synthesis of Mesoporous Palladium Nanoparticles as Highly Active Electrocatalysts 下载免费PDF全文
Dr. Cuiling Li Bo Jiang Dr. Masataka Imura Prof. Dr. Naoto Umezawa Dr. Victor Malgras Prof. Dr. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18671-18676
Mesoporous Pd nanoparticles (MPNs) enclosed by high‐index facets have been successfully prepared by taking advantage of successive oxygen adsorption and desorption caused by the oxidative etching effect. The as‐prepared MPNs exhibit excellent performance toward formic acid electro‐oxidation, which is due to the synergetic effect between the diffusion‐feasible tubular mesochannels and the high index facets. 相似文献
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Selective Transformation of Syngas into Gasoline‐Range Hydrocarbons over Mesoporous H‐ZSM‐5‐Supported Cobalt Nanoparticles 下载免费PDF全文
Dr. Kang Cheng Lei Zhang Dr. Jincan Kang Xiaobo Peng Prof. Dr. Qinghong Zhang Prof. Dr. Ye Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1928-1937
Bifunctional Fischer–Tropsch (FT) catalysts that couple uniform‐sized Co nanoparticles for CO hydrogenation and mesoporous zeolites for hydrocracking/isomerization reactions were found to be promising for the direct production of gasoline‐range (C5–11) hydrocarbons from syngas. The Brønsted acidity results in hydrocracking/isomerization of the heavier hydrocarbons formed on Co nanoparticles, while the mesoporosity contributes to suppressing the formation of lighter (C1–4) hydrocarbons. The selectivity for C5–11 hydrocarbons could reach about 70 % with a ratio of isoparaffins to n‐paraffins of approximately 2.3 over this catalyst, and the former is markedly higher than the maximum value (ca. 45 %) expected from the Anderson–Schulz–Flory distribution. By using n‐hexadecane as a model compound, it was clarified that both the acidity and mesoporosity play key roles in controlling the hydrocracking reactions and thus contribute to the improved product selectivity in FT synthesis. 相似文献
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Dr. Xiaoxia Zhou Prof. Hangrong Chen Dr. Yan Zhu Yudian Song Dr. Yu Chen Dr. Yongxia Wang Dr. Yun Gong Dr. Guobin Zhang Dr. Zhu Shu Dr. Xiangzhi Cui Dr. Jinjin Zhao Prof. Jianlin Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(30):10017-10023
Dual‐mesoporous ZSM‐5 zeolite with highly b axis oriented large mesopores was synthesized by using nonionic copolymer F127 and cationic surfactant CTAB as co‐templates. The product contains two types of mesopores—smaller wormlike ones of 3.3 nm in size and highly oriented larger ones of 30–50 nm in diameter along the b axis—and both of them interpenetrate throughout the zeolite crystals and interconnect with zeolite microporosity. The dual‐mesoporous zeolite exhibits excellent catalytic performance in the condensation of benzaldehyde with ethanol and greater than 99 % selectivity for benzoin ethyl ether at room temperature, which can be ascribed to the zeolite lattice structure offering catalytically active sites and the hierarchical and oriented mesoporous structure providing fast access of reactants to these sites in the catalytic reaction. The excellent recyclability and high catalytic stability of the catalyst suggest prospective applications of such unique mesoporous zeolites in the chemical industry. 相似文献
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Inside Cover: Selective Transformation of Syngas into Gasoline‐Range Hydrocarbons over Mesoporous H‐ZSM‐5‐Supported Cobalt Nanoparticles (Chem. Eur. J. 5/2015) 下载免费PDF全文
Dr. Kang Cheng Lei Zhang Dr. Jincan Kang Xiaobo Peng Prof. Dr. Qinghong Zhang Prof. Dr. Ye Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):1822-1822
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Well‐Defined Palladium Nanoparticles Supported on Siliceous Mesocellular Foam as Heterogeneous Catalysts for the Oxidation of Water 下载免费PDF全文
Dr. Oscar Verho Dr. Torbjörn Åkermark Dr. Eric V. Johnston Karl P. J. Gustafson Dr. Cheuk‐W. Tai Henrik Svengren Dr. Markus D. Kärkäs Prof. Jan‐E. Bäckvall Prof. Björn Åkermark 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5909-5915
Herein, we describe the use of Pd nanoparticles immobilized on an amino‐functionalized siliceous mesocellular foam for the catalytic oxidation of H2O. The Pd nanocatalyst proved to be capable of mediating the four‐electron oxidation of H2O to O2, both chemically and photochemically. The Pd nanocatalyst is easy to prepare and shows high chemical stability, low leaching, and recyclability. Together with its promising catalytic activity, these features make the Pd nanocatalyst of potential interest for future sustainable solar‐fuel production. 相似文献
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Yasmine Guefrachi Geetu Sharma Dandan Xu Gaurav Kumar Katherine P. Vinter Omar A. Abdelrahman Xinyu Li Saeed Alhassan Paul J. Dauenhauer Alexandra Navrotsky Wei Zhang Michael Tsapatsis 《Angewandte Chemie (International ed. in English)》2020,59(24):9579-9585
Commonly used methods to assess crystallinity, micro‐/mesoporosity, Brønsted acid site density and distribution (in micro‐ vs. mesopores), and catalytic activity suggest nearly invariant structure and function for aluminosilicate zeolite MFI two‐dimensional nanosheets before and after superheated steam treatment. Yet, pronounced reaction rate decrease for benzyl alcohol alkylation with mesitylene, a reaction that cannot take place in the zeolite micropores, is observed. Transmission electron microscopy images reveal pronounced changes in nanosheet thickness, aspect ratio and roughness indicating that nanosheet coarsening and the associated changes in the external (mesoporous) surface structure are responsible for the changes in the external surface catalytic activity. Superheated steam treatment of hierarchical zeolites can be used to alter nanosheet morphology and regulate external surface catalytic activity while preserving micro‐ and mesoporosity, and micropore reaction rates. 相似文献
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Copper/Palladium Synergistic Catalysis for the syn‐ and anti‐Selective Carboboration of Alkenes 下载免费PDF全文
Kaitlyn M. Logan Kevin B. Smith Prof. M. Kevin Brown 《Angewandte Chemie (International ed. in English)》2015,54(17):5228-5231
A method for the diastereoselective carboboration of 1,2‐disubstituted styrenes with aryl/vinyl bromides and (Bpin)2 is reported. High diastereoselectivities and yields are observed for the formation of either diastereomer of the product from a single alkene isomer. These reactions provide access to a diverse range of structures from simple starting materials. 相似文献
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Xuefeng Shen Wenting Mao Dr. Yanhang Ma Dr. Dongdong Xu Prof. Dr. Peng Wu Prof. Dr. Osamu Terasaki Prof. Dr. Lu Han Prof. Dr. Shunai Che 《Angewandte Chemie (International ed. in English)》2018,57(3):724-728
A conceptual design and synthesis of ordered mesoporous zeolites is a challenging research subject in material science. Several seminal articles report that one‐dimensional (1D) mesostructured lamellar zeolites are possibly directed by sheet‐assembly of surfactants, which collapse after removal of intercalated surfactants. However, except for one example of two‐dimensional (2D) hexagonal mesoporous zeolite, no other zeolites with ordered 2D or three‐dimensional (3D) mesostructures have been reported. An ordered 2D mesoporous zeolite can be templated by a cylindrical assembly unit with specific interactions in the hydrophobic part. A template molecule with azobenzene in the hydrophobic tail and diquaternary ammonium in the hydrophilic head group directs hierarchical MFI zeolite with a 2D square mesostructure. The material has an elongated octahedral morphology, and quaternary, ordered, straight, square channels framed by MFI thin sheets expanded along the a–c planes and joined with 90° rotations. The structural matching between the cylindrical assembly unit and zeolite framework is crucial for mesostructure construction. 相似文献