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Polymer-stabilized noble metal colloids were efficiently immobilized on silica by the addition of organic acids under mild conditions. The function of organic acids in the immobilization was studied by infrared spectroscopy. Transmission electron micrographs indicate that the immobilized colloids have a controlled particle size and size distribution. They serve as catalysts in the hydrogenation of cyclohexene and cyclopentadiene, the results of which show that this new type of immobilized colloid has high selectivity and good stability. 相似文献
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Huang Jianping Chen Fang Wang He Yan Hongge 《Research on Chemical Intermediates》2018,44(4):2729-2738
Research on Chemical Intermediates - The combination of the unique properties of graphene with functional characteristics of metal oxides is an interesting pathway to achieve desirable properties... 相似文献
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Chao Li Prof. Dr. Yongfeng Liu Yingjie Gu Mingxia Gao Prof. Dr. Hongge Pan 《化学:亚洲杂志》2013,8(9):2136-2143
The introduction of RbF into the Mg(NH2)2–2 LiH system significantly decreased its (de‐)hydrogenation temperatures and enhanced its hydrogen‐storage kinetics. The Mg(NH2)2–2 LiH–0.08 RbF composite exhibits the optimal hydrogen‐storage properties as it could reversibly store approximately 4.76 wt % hydrogen through a two‐stage reaction with the onset temperatures of 80 °C for dehydrogenation and 55 °C for hydrogenation. At 130 °C, approximately 70 % of hydrogen was rapidly released from the 0.08 RbF‐doped sample within 180 min, and the fully dehydrogenated sample could absorb approximately 4.8 wt % of hydrogen at 120 °C. Structural analyses revealed that RbF reacted readily with LiH to convert to RbH and LiF owing to the favorable thermodynamics during ball‐milling. The newly generated RbH participated in the following dehydrogenation reaction, consequently resulting in a decrease in the reaction enthalpy change and activation energy. 相似文献
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Jianhui Wang Tao Liu Dr. Guotao Wu Dr. Wen Li Yongfeng Liu Dr. C. Moysés Araújo Dr. Ralph H. Scheicher Dr. Andreas Blomqvist Rajeev Ahuja Prof. Zhitao Xiong Dr. Ping Yang Dr. Mingxia Gao Dr. Hongge Pan Prof. Ping Chen Prof. 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2009,121(32):5942-5946
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Liu Y Liang C Zhou H Gao M Pan H Wang Q 《Chemical communications (Cambridge, England)》2011,47(6):1740-1742
A synergetic effect of K, Ti and F together on improving the reversible hydrogen storage properties of NaAlH(4) is found by intruding K(2)TiF(6) as catalyst precursor. Around 4.4 wt% of hydrogen can be released from the NaAlH(4)-0.025 K(2)TiF(6) sample within 40 min at 140 °C. 相似文献
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Liang C Liu Y Jiang Y Wei Z Gao M Pan H Wang Q 《Physical chemistry chemical physics : PCCP》2011,13(1):314-321
A mechanistic understanding on the enhanced kinetics of hydrogen storage in the NaBH(4)-added Mg(NH(2))(2)-2LiH system is provided by carrying out experimental investigations associated with first-principles calculations. It is found that the operating temperatures for hydrogen desorption of the Mg(NH(2))(2)-2LiH system are reduced by introducing NaBH(4), and the NaBH(4) species seems almost unchanged during dehydrogenation/hydrogenation process. First-principles calculations reveal that the presence of NaBH(4) in the Mg(NH(2))(2)-2LiH system facilitates the formation of Mg vacancies in Mg(NH(2))(2). The appearance of Mg vacancies not only weakens the N-H bonds but also promotes the diffusion of atoms and/or ions, consequently resulting in the improvement of the reaction kinetics of hydrogen desorption/absorption of the NaBH(4)-added Mg(NH(2))(2)-2LiH system. This finding provides us with a deep insight into the role played by NaBH(4) in the Li-Mg-N-H system, as well as ideas for designing high-performance catalysts for metal-N-H-based hydrogen storage media. 相似文献
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Let Q be a bounded open domain in R^n with smooth boundaryаΩ.Let X=(X1,X2…,Xm)be a system of general Grushin type vector fields defined onΩand the boundaryаΩis non-characteristic for X.For△x=∑j=1^mXj^2,we denoteλk as the k-th eigenvalue for the bi-subelliptic operator△X2^2 onΩ.In this paper,by using the sharp sub-elliptic estimates and maximally hypoeliptic estimates,we give the optimal lower bound estimates ofλk for the operatork△X^2. 相似文献
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Yazhen Wang Rifang Li Hongge Jia Guoxing Yang Yutao Di Chenxi Xu Liqun Ma Hui Zhang Yongli Zhou Yu Zang Shuangping Xu Zhaoyang Sun Liwu Zu Chenge Yue Tianyu Lan 《Chemical Papers》2018,72(11):2871-2877
A novel peroxy group-containing silane coupling agent was synthesized and anchored on the surface of titanium dioxide nanoparticles (nano-TiO2) to form an immobilized-initiator-modified nano-TiO2 species. In this study, the kinetic parameters of the peroxy group-containing silane were tested and assessed using DSC. The pre-exponential factor (Ad) was 8.973?×?108 and the activation energy (Ea) was 80.736 kJ mol?1. Moreover, the empirical Arrhenius equation was determined to be ln Kd?=???80.736/RT?+?ln(8.973?×?108). To obtain continuous polymers, acrylonitrile (AN) and methyl methacrylate (MMA) were polymerized using the novel peroxy group-containing silane and FeSO4 as an initiator system. The number average molecular weights (Mn of PAN?=?3×104 and Mn of PMMA?=?1.4?×?105) and polydispersity indexes (PDI of PAN?=?2.76 and PDI of PMMA?=?1.65) were determined by GPC. It was suggested that the redox initiation system can generate highly reactive species on the surfaces of inorganic nanoparticles. The nano-TiO2-grafted polymers were successfully obtained. 相似文献