共查询到20条相似文献,搜索用时 15 毫秒
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Pingping Hu Zhiwei Huang Dr. Zakariae Amghouz Prof. Michiel Makkee Fei Xu Prof. Freek Kapteijn Dr. Alla Dikhtiarenko Yaxin Chen Dr. Xiao Gu Prof. Xingfu Tang 《Angewandte Chemie (International ed. in English)》2014,53(13):3418-3421
The synthesis of single‐atom catalysts and the control of the electronic properties of catalytic sites to arrive at superior catalysts is a major challenge in heterogeneous catalysis. A stable supported single‐atom silver catalyst with a controllable electronic state was obtained by anti‐Ostwald ripening. An electronic perturbation of the catalytic sites that is induced by a subtle change in the structure of the support has a strong influence on the intrinsic reactivity. The higher depletion of the 4d electronic state of the silver atoms causes stronger electronic metal–support interactions, which leads to easier reducibility and higher catalytic activity. These results may improve our understanding of the nature of electronic metal–support interactions and lead to structure–activity correlations. 相似文献
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A Case of Strong Metal–Support Interactions: Combining Advanced Microscopy and Model Systems to Elucidate the Atomic Structure of Interfaces
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Dr. Marc G. Willinger Dr. Wei Zhang Dr. Oleksandr Bondarchuk Dr. Shamil Shaikhutdinov Prof. Dr. Hans‐Joachim Freund Prof. Dr. Robert Schlögl 《Angewandte Chemie (International ed. in English)》2014,53(23):5998-6001
A symbiosis of advanced scanning probe and electron microscopy and a well‐defined model system may provide a detailed picture of interfaces on nanostructured catalytic systems. This was demonstrated for Pt nanoparticles supported on iron oxide thin films which undergo encapsulation by supporting oxide as a result of strong metal–support interactions. 相似文献
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Li‐Na Wang Dr. Xiao‐Na Li Li‐Xue Jiang Bin Yang Dr. Qing‐Yu Liu Dr. Hong‐Guang Xu Prof. Wei‐Jun Zheng Prof. Sheng‐Gui He 《Angewandte Chemie (International ed. in English)》2018,57(13):3349-3353
Catalytic CO oxidation by molecular O2 is an important model reaction in both the condensed phase and gas‐phase studies. Available gas‐phase studies indicate that noble metal is indispensable in catalytic CO oxidation by O2 under thermal collision conditions. Herein, we identified the first example of noble‐metal‐free heteronuclear oxide cluster catalysts, the copper–vanadium bimetallic oxide clusters Cu2VO3–5? for CO oxidation by O2. The reactions were characterized by mass spectrometry, photoelectron spectroscopy, and density functional calculations. The dynamic nature of the Cu?Cu unit in terms of the electron storage and release is the driving force to promote CO oxidation and O2 activation during the catalysis. 相似文献
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Inside Cover: Electronic Metal–Support Interactions in Single‐Atom Catalysts (Angew. Chem. Int. Ed. 13/2014)
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Pingping Hu Zhiwei Huang Dr. Zakariae Amghouz Prof. Michiel Makkee Fei Xu Prof. Freek Kapteijn Dr. Alla Dikhtiarenko Yaxin Chen Dr. Xiao Gu Prof. Xingfu Tang 《Angewandte Chemie (International ed. in English)》2014,53(13):3284-3284
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Template‐Induced Diverse Metal–Organic Materials as Catalysts for the Tandem Acylation–Nazarov Cyclization
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Chao Huang Ran Ding Prof. Chuanjun Song Jingjing Lu Lu Liu Xiao Han Prof. Jie Wu Hongwei Hou Prof. Yaoting Fan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16156-16163
In our continuing quest to develop a metal–organic framework (MOF)‐catalyzed tandem pyrrole acylation–Nazarov cyclization reaction with α,β‐unsaturated carboxylic acids for the synthesis of cyclopentenone[b]pyrroles, which are key intermediates in the synthesis of natural product (±)‐roseophilin, a series of template‐induced Zn‐based ( 1–3 ) metal‐organic frameworks (MOFs) have been solvothermally synthesized and characterized. Structural conversions from non‐porous MOF 1 to porous MOF 2 , and back to non‐porous MOF 3 arising from the different concentrations of template guest have been observed. The anion–π interactions between the template guests and ligands could affect the configuration of ligands and further tailor the frameworks of 1–3 . Futhermore, MOFs 1–3 have shown to be effective heterogeneous catalysts for the tandem acylation–Nazarov cyclization reaction. In particular, the unique structural features of 2 , including accessible catalytic sites and suitable channel size and shape, endow 2 with all of the desired features for the MOF‐catalyzed tandem acylation–Nazarov cyclization reaction, including heterogeneous catalyst, high catalytic activity, robustness, and excellent selectivity. A plausible mechanism for the catalytic reaction has been proposed and the structure–reactivity relationship has been further clarified. Making use of 2 as a heterogeneous catalyst for the reaction could greatly increase the yield of total synthesis of (±)‐roseophilin. 相似文献
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Dr. Nuo‐Wei Zhang Prof. Chuan‐Jing Huang Xiao‐Quan Zhu Jing‐Dong Xu Prof. Wei‐Zheng Weng Prof. Hui‐Lin Wan 《化学:亚洲杂志》2012,7(8):1895-1901
The effects of calcination temperature and feedstock pretreatment on the catalytic performance of Co/γ‐Al2O3 catalysts were studied for partial oxidation of methane (POM) to synthesis gas, with emphasis on the role of feedstock pretreatment. The physicochemical properties of the catalysts were characterized by N2 adsorption, X‐ray diffraction (XRD), transmission electron microscopy (TEM), H2 temperature‐programmed reduction (H2‐TPR), and Raman spectroscopy. The results showed that the pretreatment of the catalyst by reaction gas significantly improved the catalytic activity and stability for the POM reaction. On the other hand, the effect of calcination temperature was less significant. Although the initial activity was increased by an increased calcination temperature, the catalyst without the feedstock pretreatment suffered a rapid deactivation. The reaction‐atmosphere pretreatment was revealed as a process that mainly modified the surface structure of the catalyst. In that process, the formation of a CoAl2O4‐like compound led to high Co metal dispersion after reduction, and the transformation of the carrier into α‐Al2O3 occurred over the catalyst surface. Both the high dispersion of cobalt and the presence of α‐Al2O3 surface phase were assumed as the important factors resulting in an excellent catalytic performance in terms of high activity and high stability. 相似文献
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甲醇水蒸气重整制氢的高效碳纳米管改性Cu/ZnO/Al2O3催化剂 总被引:1,自引:1,他引:1
以碳纳米管为助剂,制备用于甲醇水蒸气重整制氢的新型高效Cu/ZnO/Al2O3催化剂,并与传统Cu/ZnO/Al2O3催化剂在相同条件下的催化性能进行了比较.结果表明,添加适量碳纳米管可显著提高催化剂的低温催化活性和选择性,在大幅度提高产氢速率的同时有效降低了重整产气中CO的含量.SEM和XRD分析证实适量碳纳米管的添加有效促进了Cu/ZnO/Al2O3催化剂结构特性的改善,有利于活性铜物种的分散,从而显著提高了催化剂的低温催化性能. 相似文献
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Dr. Yaoqi Li Dr. Ping Song Prof. Jie Zheng Prof. Xingguo Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(35):10887-10892
The application of ammonium borane (AB) as a hydrogen storage material is limited by the sluggish kinetics of H2 release. Two catalysts based on metal–organic frameworks (MOFs) have been prepared either by applying MOF as precursors or by the in situ reduction method. In the release of H2 from AB, the high H2 content of the whole system, the remarkably lower reaction onset temperature, the significantly increased H2 release rates at ≤90 °C, and the decreased reaction exothermicity have all been achieved with only 1.0 mol % MOF‐based catalyst. Moreover, the clear catalytic diversity of three catalysts has been observed and discussed. The in situ synthesized Ni0 sites and the MOF supports in the catalysts were proven to show significant and different effects to promote the catalytic activities. With MOF‐based catalysts, both the enhanced kinetics and the high H2 capacity of the AB system present great advantages for future use. 相似文献
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Jurjen Spekreijse Prof. Lars Öhrström Prof. Johan P. M. Sanders Prof. Johannes H. Bitter Dr. Elinor L. Scott 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15437-15443
A simple, one‐step mechanochemical procedure for immobilisation of homogeneous metathesis catalysts in metal–organic frameworks was developed. Grinding MIL‐101‐NH2(Al) with a Hoveyda–Grubbs second‐generation catalyst resulted in a heterogeneous catalyst that is active for metathesis and one of the most stable immobilised metathesis catalysts. During the mechanochemical immobilisation the MIL‐101‐NH2(Al) structure was partially converted to MIL‐53‐NH2(Al). The Hoveyda–Grubbs catalyst entrapped in MIL‐101‐NH2(Al) is responsible for the observed catalytic activity. The developed synthetic procedure was also successful for the immobilisation of a Zhan catalyst. 相似文献
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Enhanced Activity of CuCeO Catalysts for CO Oxidation: Influence of Cu2O and the Dispersion of Cu2O,CuO, and CeO2
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CuCeO catalysts prepared by a hydrothermal method with subsequent calcination are tested for the catalytic oxidation of CO. This synthesis method leads to a homogeneous dispersion of Cu2O, CuO, and CeO2 in the catalysts. The composition of the catalysts is determined by the molar ratio of the metals, the hydrothermal process, and calcination temperature and influences the catalytic performance. The catalyst containing Cu2O exhibits high catalytic activity with almost 100 % CO conversion at 105 °C and shows excellent stability with the conversion ratio not decreasing after four months of storage. 相似文献
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Chengshan Dai Dr. Ying Zhang Junnan Chen Dr. Xia Zhong Dr. Liyun Zhang Prof. Dr. Bingsen Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(34):e202200199
Selective hydrogenation of substituted nitroaromatic compounds is an extremely important and challenging reaction. Supported metal catalysts attract much attention in this reaction because the properties of metal nanoparticles (NPs) can be modified by the nature of the support. Herein, the support morphology on the catalytic performance of selective hydrogenation of 3-nitrostyrene to 3-vinylaniline was investigated. Pt NPs supported on octadecahedral α-Fe2O3 supports with a truncated hexagonal bipyramid shape (Pt/α-Fe2O3-O) and rod-shaped α-Fe2O3 supports (Pt/α-Fe2O3-R) were prepared by glycol reduction method. Detailed characterizations reveal that the electronic structure and dispersion of Pt NPs can be modified by the supports. The Pt/α-Fe2O3-O catalyst exhibited superior catalytic performance for hydrogenation of 3-nitrostyrene because of its low coordinated Pt sites and the small Pt NPs size, which is benefit from the high-index exposed surfaces of truncated hexagonal bipyramid-shaped α-Fe2O3 support. The structural evolution during the catalytic reaction was investigated in detail by identical location transmission electron microscopy (IL-TEM) method, which found that the high cycling activity of Pt/α-Fe2O3-O catalyst during the cycle experiment results from the stability of Pt NPs. 相似文献
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Zaccheria F Ravasio N Psaro R Fusi A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(24):6426-6431
A method for the anaerobic oxidation of a wide series of alcohols including cyclohexanols and steroidal alcohols, has been set up. It relies on a transfer dehydrogenation reaction from the substrate alcohol to styrene catalyzed by a heterogeneous, reusable copper catalyst under very mild liquid-phase experimental conditions (90 degrees C, N(2)) and shows unusual selectivity. Thus, the method is selective for the oxidation of secondary and allylic alcohols even in the presence of unprotected primary and benzylic alcohols. Electronic effects and the choice of the hydrogen acceptor account for the selectivity observed. 相似文献
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凝胶网格共沉淀法制备Cu/ZnO/Al2O3合成甲醇催化剂 总被引:11,自引:0,他引:11
随着工业污染和温室效应等环境问题及能源危机和资源危机的日益严重,以二氧化碳为原料催化合成甲醇等化学品已成为C;化工研究中最重要的前沿课题之一[‘-’j.CO。加氢合成甲醇的研究虽已有 相似文献
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分别以碳酸铵为沉淀剂采用共沉淀-蒸氨法(CAE)和以碳酸铵(CCA)、碳酸钠(CCS)为沉淀剂采用常规共沉淀法制备了三种Cu/ZnO/Al2O3催化剂,并运用XRD,BET,TPR和N2O滴定技术对催化剂进行了表征.结果表明:采用共沉淀-蒸氨法制备的催化剂具有较小的颗粒尺寸、较大的Cu(0)比表面积;以碳酸铵为沉淀剂常... 相似文献
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Adaptation o Cu/ZnO/Al2O3 to Temperature Change in Methanol Synthesis from CO2 Hydrogenation
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The induction behavior in CO2 hydrogenation was studied by varying the reaction temperature to investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change,The results indicated that a used catalyst had a tendency to keep the last running state in new reaction conditions for MeOH formation,and that this tendency was related to the difference in Cu/Cu^n ration caused by CO2 and CO produced at different reaction temperatures,However,the reverse water-gas shift reaction (BWGS) induced at four temperatures was completely different from that of methanol synthesis,It implied that the two so-called competitive reactions in CO2 H2,RWGS and methanol synthesis,have different, active centers. 相似文献
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Hydroxyl‐Mediated Non‐oxidative Propane Dehydrogenation over VOx/γ‐Al2O3 Catalysts with Improved Stability
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Dr. Zhi‐Jian Zhao Tengfang Wu Chuanye Xiong Guodong Sun Dr. Rentao Mu Dr. Liang Zeng Prof. Dr. Jinlong Gong 《Angewandte Chemie (International ed. in English)》2018,57(23):6791-6795
Supported vanadium oxides are one of the most promising alternative catalysts for propane dehydrogenation (PDH) and efforts have been made to improve its catalytic performance. However, unlike Pt‐based catalysts, the nature of the active site and surface structure of the supported vanadium catalysts under reductive reaction conditions still remain elusive. This paper describes the surface structure and the important role of surface‐bound hydroxyl groups on VOx / γ‐Al2O3 catalysts under reaction conditions employing in situ DRIFTS experiments and DFT calculations. It is shown that hydroxyl groups on the VOx /Al2O3 catalyst (V?OH) are produced under H2 pre‐reduction, and the catalytic performance for PDH is closely connected to the concentration of V?OH species on the catalyst. The hydroxyl groups are found to improve the catalyst that leads to better stability by suppressing the coke deposition. 相似文献
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浆态床合成甲醇CuO/ZnO/Al2O3催化剂的表面性质 总被引:3,自引:0,他引:3
采用并流共沉淀法制备了不同Cu/Zn摩尔比的CuO/ZnO/Al2O3催化剂,考察了其浆态床CO加氢合成甲醇的催化性能.通过N2吸附-脱附、X射线衍射、程序升温还原及X射线光电子能谱等方法对催化剂表面性质进行了表征.结果表明,催化剂具有体相和表面高分散两种不同还原性质的CuO,表面CuO的含量及其与ZnO的相互作用使催化剂活性增大.当催化剂中Cu/Zn≤1时,随着铜含量的增加,表面高分散的CuO量增加,CuO和ZnO之间相互作用增强,催化剂的活性也随之增大;当催化剂Cu/Zn>1时,增加的铜量主要体现为体相CuO含量的增加,且ZnO结晶度提高,CuO和ZnO之间的相互作用减弱,催化剂的活性随铜含量增大而减小. 相似文献