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Theoretical Study on the Adsorption and Hydrogenation Mechanism of 2-Methylthiophene over the Pt(111) Catalyst
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作者 施炜 倪哲明 +1 位作者 夏盛杰 苏为科 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2017年第12期1961-1974,共14页
The adsorption process and hydrogenation mechanisms of 2-methylthiophene on the Pt(111) surface have been elucidated using density functional theory(DFT). The optimal adsorption sites of reactants, intermediates, ... The adsorption process and hydrogenation mechanisms of 2-methylthiophene on the Pt(111) surface have been elucidated using density functional theory(DFT). The optimal adsorption sites of reactants, intermediates, and products as well as the activation energy and reaction energy of each elementary reactions were investigated. The results turned out that the 2-methylthiophene tilt to the Pt(111) catalyst with the C_1–C_2 double bond at the top site was the most stable. During the hydrogenation process, the heat of reaction almost located at the negative side, so dropping the temperature is good for the occurrence of hydrogenation process. The hydrogenation steps of mechanism take place along C_2→C_3→C_1→C_4→S→C_1 to generate the product of pentane-2-thiol, in which the first step with the highest energy barrier is the rate-determining step. 展开更多
关键词 density functional theory 2-methylthiophene Pt(111) ADSORPTION hydrogenation mechanisms
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THEORETICAL ANALYSIS OF HYDROGENATION MECHANISM CATALYZED BY Pd-Fe_2O_3/D_(3520)
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作者 胡卫兵 张胜民 张曼征 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 1996年第4期35-38,共4页
The mechanism of catalytic hydrogenation of styrene is analyzed by catalysis theory and frontier molecular orbital theory.
关键词 olefinic double bonds hydrogenation mechanism frontier molecular orbital theory
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DFT Studies on Hydrogen Overfall Mechanism for Catalyzed Hydroisomerization of Pentane 被引量:1
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作者 AI Chun-Zhi SUN Ren-An WANG Chang-Sheng 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2007年第2期239-247,共9页
The mechanism and related reaction paths in the hydroisomerization of n-pentane were studied by DFT calculations at the B3LYP/6-311++G^** level. Two possible transition states were theoretically predicted and ve... The mechanism and related reaction paths in the hydroisomerization of n-pentane were studied by DFT calculations at the B3LYP/6-311++G^** level. Two possible transition states were theoretically predicted and verified by the vibration frequency analysis as well as the calculations of intrinsic reaction coordinates (IRC). Furthermore, the related reaction barriers were evaluated by single point energy at the MP2/6-311++G^** level with zero point vibration correction of DFT method. Thus, it is concluded that the isomerization might go through two pathways. 展开更多
关键词 catalyzed isomerization of n-pentane hydrogen overfall mechanism i-pentane DFT
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Decomposition of a β-O-4 lignin model compound over solid Cs-substituted polyoxometalates in anhydrous ethanol: acidity or redox property dependence? 被引量:1
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作者 吴学众 焦文千 +4 位作者 李秉正 黎演明 张亚红 王全瑞 唐颐 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第7期1216-1228,共13页
Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for de... Production o f aromatics from lignin has attracted much attention. Because of the coexistence of C-O and C-C bonds and their complex combinations in the lignin macromolecular network, a plausible roadmap for developing a lignin catalytic decomposition process could be developed by exploring the transformation mechanisms of various model compounds. Herein, decomposition of a lignin model compound, 2-phenoxyacetophenone (2-PAP), was investigated over several ce-sium-exchanged polyoxometalate (Cs-POM) catalysts. Decomposition of 2-PAP can follow two dif-ferent mechanisms: an active hydrogen transfer mechanism or an oxonium cation mechanism. The mechanism for most reactions depends on the competition between the acidity and redox proper-ties of the catalysts. The catalysts of POMs perform the following functions: promoting active hy-drogen liberated from ethanol and causing formation of and then temporarily stabilizing oxonium cations from 2-PAP. The use of Cs-PMo, which with strong redox ability, enhances hydrogen libera-tion and promotes liberated hydrogen transfer to the reaction intermediates. As a consequence, complete conversion of 2-PAP (〉99%) with excellent selectivities to the desired products (98.6% for phenol and 91.1% for acetophenone) can be achieved. 展开更多
关键词 Lignin model compound β-O-4 ether bond POLYOXOMETALATE Hydrogen transfer mechanism Oxonium cation mechanism Anhydrous ethanol
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Theoretical Study on the Excited-state Intramolecular Hydrogen Abstraction Reactions of Butanal 被引量:1
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作者 吕玲玲 杨声 +2 位作者 袁琨 王小芳 王永成 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第10期1226-1235,共10页
The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluo... The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluorescence quenching of the n,π^*-excited state of covalent butanal with three paths: (1) The first path corresponds to direct S0-react reconstitution, which involves the first S1 decay by partial hydrogen atom transfer. (2) The second stepwise mechanism can be viewed as a full hydrogen atom transfer followed by a partial hydrogen atom back transfer, electron transfer (near S1/S0 or S0-TS) and finally a proton transfer to S0-react. (3) On the triplet surface, the surface crossing to the singlet state would be clearly much efficient at the T1/S0 region due to the large SOC value of 8.3 cm^-1. The S0-react decay route from T1/S0 was studied with an intrinsic reaction coordinate (IRC) calculation at the CASSCF level, resulting in the S0-React minimum. 展开更多
关键词 butanal valence bond theory (VB) state correlation diagram hydrogen abstraction mechanism
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INVESTIGATION OF HYDROGEN INDUCED DUCTILE BRITTLE TRANSITION IN 7175 ALUMINUM ALLOY 被引量:8
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作者 R.G.Seng: B.J Zhong, MG. Zeng and P. Geng(Department of Materials Scierce, Science College,Northearstern Univeisity, Shenyang 110006, China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1996年第4期287-290,共4页
Effects of hydrogen on the mechanical properties of differently aged 7175 aluminum alloys were investigated by using cathodic H-permeation, slow strain rate tension and so on. The results indicate that both the yield ... Effects of hydrogen on the mechanical properties of differently aged 7175 aluminum alloys were investigated by using cathodic H-permeation, slow strain rate tension and so on. The results indicate that both the yield stress and the percentage reduction of area decrease with increasing hydrogen charging time, and the degree of reduction decreases as aging time increases for the same hydrogen charging time. 展开更多
关键词 hydrogen induced ductile-brittle transition 7175 aluminum alloy mechanical property cathodic H-permeation
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An Investigation on Hydrogen Storage Kinetics of the Nanocrystalline and Amorphous LaMg12-type Alloys Synthesized by Mechanical Milling 被引量:2
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作者 张羊换 WANG Jinglong +3 位作者 ZHANG Peilong ZHU Yongguo HOU Zhonghui SHANG Hongwei 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第2期278-287,共10页
Nanocrystalline and amorphous LaMg_(12)-type LaMg_(11)Ni + x wt% Ni(x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydroge... Nanocrystalline and amorphous LaMg_(12)-type LaMg_(11)Ni + x wt% Ni(x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydrogen storage kinetics of as-milled alloys were investigated systematically. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. And the gaseous hydrogen storage properties were investigated by Sievert apparatus and a differential scanning calorimeter(DSC) connected with a H_2 detector. Hydrogen desorption activation energy of alloy hydrides was estimated by using Arrhenius and Kissinger methods. It is found that the increase of Ni content significantly improves the gaseous and electrochemical hydrogen storage kinetic performances of as-milled alloys. Furthermore, as ball milling time changes, the maximum of both high rate discharge ability(HRD) and the gaseous hydriding rate of as-milled alloys can be obtained. But the hydrogen desorption kinetics of alloys always increases with the extending of milling time. Moreover, the improved gaseous hydrogen storage kinetics of alloys are ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and milling time. 展开更多
关键词 LaMg12 alloy mechanical milling activation energy hydrogen storage kinetics
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Review of Hydrogen Embrittlement in Metals: Hydrogen Diffusion, Hydrogen Characterization, Hydrogen Embrittlement Mechanism and Prevention 被引量:22
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作者 Xinfeng Li Xianfeng Ma +3 位作者 Jin Zhang Eiji Akiyama Yanfei Wang Xiaolong Song 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2020年第6期759-773,共15页
Hydrogen dissolved in metals as a result of internal and external hydrogen can affect the mechanical properties of the metals, principally through the interactions between hydrogen and material defects. Multiple pheno... Hydrogen dissolved in metals as a result of internal and external hydrogen can affect the mechanical properties of the metals, principally through the interactions between hydrogen and material defects. Multiple phenomena such as hydrogen dissolution, hydrogen diffusion, hydrogen redistribution and hydrogen interactions with vacancies, dislocations, grain boundaries and other phase interfaces are involved in this process. Consequently, several hydrogen embrittlement(HE) mechanisms have been successively proposed to explain the HE phenomena, with the hydrogen-enhanced decohesion mechanism, hydrogenenhanced localized plasticity mechanism and hydrogen-enhanced strain-induced vacancies being some of the most important. Additionally, to reduce the risk of HE for engineering structural materials in service, surface treatments and microstructural optimization of the alloys have been suggested. In this review, we report on the progress of the studies on HE in metals, with a particular focus on steels. It focuses on four aspects:(1) hydrogen diffusion behavior;(2) hydrogen characterization methods;(3) HE mechanisms;and(4) the prevention of HE. The strengths and weaknesses of the current HE mechanisms and HE prevention methods are discussed, and specific research directions for further investigation of fundamental HE mechanisms and methods for preventing HE failure are identified. 展开更多
关键词 Hydrogen embrittlement Hydrogen diffusion Hydrogen embrittlement mechanism PREVENTION
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Mechanism of Hg^0 oxidation in the presence of HCl over a commercial V_2O_5–WO_3/TiO_2 SCR catalyst 被引量:8
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作者 Ruihui Liu Wenqing Xu +1 位作者 Li Tong Tingyu Zhu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第10期76-83,共8页
Experiments were conducted in a fixed-bed reactor containing a commercial V2O5/WO3/TiO2 catalyst to investigate mercury oxidation in the presence of HCl and O2. Mercury oxidation was improved significantly in the pres... Experiments were conducted in a fixed-bed reactor containing a commercial V2O5/WO3/TiO2 catalyst to investigate mercury oxidation in the presence of HCl and O2. Mercury oxidation was improved significantly in the presence of HCl and O2, and the Hg^0 oxidation efficiencies decreased slowly as the temperature increased from 200 to 400℃. Upon pretreatment with HCl and O2 at 350℃, the catalyst demonstrated higher catalytic activity for Hg^0 oxidation. Notably,the effect of pretreatment with HCl alone was not obvious. For the catalyst treated with HCl and O2, better performance was observed with lower reaction temperatures. The results showed that both HCl and Hg^0 were first adsorbed onto the catalyst and then reacted with O2 following its adsorption, which indicates that the oxidation of Hg^0 over the commercial catalyst followed the Langmuir–Hinshelwood mechanism. Several characterization techniques, including Hg^0temperature-programmed desorption(Hg-TPD) and X-ray photoelectron spectroscopy(XPS), were employed in this work. Hg-TPD profiles showed that weakly adsorbed mercury species were converted to strongly bound species in the presence of HCl and O2. XPS patterns indicated that new chemisorbed oxygen species were formed by the adsorption of HCl, which consequently facilitated the oxidation of mercury. 展开更多
关键词 Mercury Hydrogen chloride Vanadium-based catalyst Oxidation mechanism
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Mechanism and rate constants for complete series reactions of 19 fluorophenols with atomic H 被引量:1
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作者 Rui Gao Xiaoyan Sun +2 位作者 Wanni Yu Qingzhu Zhang Wenxing Wang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2014年第1期154-159,共6页
Fluorine-containing halogenated fluorophenol may have effect as intermediate species involved in the formation of polyfluorinated dibenzo-p-dioxin/dibenzofurans (PFDDs/Fs). The mechanism for the atomic H initiated r... Fluorine-containing halogenated fluorophenol may have effect as intermediate species involved in the formation of polyfluorinated dibenzo-p-dioxin/dibenzofurans (PFDDs/Fs). The mechanism for the atomic H initiated reactions with complete series of nineteen fluorophenol congeners was studies using the density functional theory. At the MPWB1K,/6-31+G(d,p) level, the geometries and frequencies of reactants, transition states, and products were obtained, and the accurate energetic values were acquired at the MPWB 1K/6-311 +G(3df,2p) level. The rate constants were evaluated by the canonical variational transition-state theory with the small curvature tunneling contribution over a wide temperature range of 600-1000 K. The study shows that the intramolecular hydrogen-bond in the ortho-substituted FPs as well as the inductive effect of the electron-withdrawing fluorine and steric repulsion of multiple substitutions may ultimately be responsible for the relative strength of the O-H bonds in FPs. The results can be used for further studies on PFDD/Fs formation mechanism. 展开更多
关键词 fluorophenols fluorophenoxy radicals atomic H hydrogen bond reaction mechanism rate constants
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Overview of hydrogen-resistant alloys for high-pressure hydrogen environment:on the hydrogen energy structural materials 被引量:3
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作者 Jiaxing Liu Mingjiu Zhao Lijian Rong 《Clean Energy》 EI CSCD 2023年第1期99-115,共17页
With the progressive expansion of hydrogen fuel demand,hydrogen pipelines,hydrogen storage cylinders and hydrogen refuelling stations(HRSs)are the primary components of hydrogen energy systems that face high-pressure ... With the progressive expansion of hydrogen fuel demand,hydrogen pipelines,hydrogen storage cylinders and hydrogen refuelling stations(HRSs)are the primary components of hydrogen energy systems that face high-pressure hydrogen environments.Hydrogen embrittlement(HE)is a typical phenomenon in metallic materials,particularly in the high-pressure hydrogen environment,that causes loss of ductility and potentially catastrophic failure.HE is associated with materials,the service environment and stress.The primary mechanisms for explaining the HE of materials are hydrogen-enhanced decohesion,hydrogen-induced phase transformation,hydrogen-enhanced local plasticity,adsorption-induced dislocation emission and hydrogen-enhanced strain-induced vacancy.To reduce the risk of HE for metallic structural materials used in hydrogen energy systems,it is crucial to reasonably select hydrogen-resistant materials for high-pressure hydrogen environments.This paper summarizes HE phenomena,mechanisms and current problems for the metallic structural materials of hydrogen energy systems.A research perspective is also proposed,mainly focusing on metal structural materials for hydrogen pipelines,hydrogen storage cylinders and hydrogen compressors in HRSs from an application perspective. 展开更多
关键词 hydrogen energy hydrogen refuelling station hydrogen pipelines hydrogen storage cylinder hydrogen embrittlement hydrogen embrittlement mechanism
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Thermal,physical and mechanical properties of hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers 被引量:4
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作者 Feng Jia Jin-Long Mao +2 位作者 Xue-Yun Yang Yan Ma Cheng Yao 《Chinese Chemical Letters》 SCIE CAS CSCD 2013年第7期654-658,共5页
Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenu... Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. The results showed that incorporation of Nylon 66 into hydrogenated dimer acid-based Nylon had no significant effect on the glass transition or melting temperatures. However, the crystallization temperature, crystallinity degree and the maximum rate of decomposition temperature from derivative thermogravimetry measurements vary. Mechanical testing data revealed that with increasing Nylon 66 concentrations, the tensile strength of copolymers increased, while the elongation at break point and notched izod impact strength decreased. The physical and mechanical properties of HN-40, HN-50 and HN-60 are similar to those of the current PAl 1, PAl212, and PAlll 1 Nylon products. 展开更多
关键词 Nylon Hydrogenated dimer acid Thermal properties Mechanical properties
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Hydrogen Storage Thermodynamics and Dynamics of Nd–Mg–NiBased Nd Mg_(12^-)Type Alloys Synthesized by Mechanical Milling 被引量:1
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作者 Yang-Huan Zhang Ze-Ming Yuan +3 位作者 Wen-Gang Bu Feng Hu Ying Cai Dong-Liang Zhao 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2016年第6期577-586,共10页
Nanocrystalline and amorphous Nd Mg_(12^-)type Nd Mg_(11)Ni+ x wt% Ni(x=100, 200) hydrogen storage alloys were synthesized by mechanical milling. The effects of Ni content and milling time on hydrogen storage t... Nanocrystalline and amorphous Nd Mg_(12^-)type Nd Mg_(11)Ni+ x wt% Ni(x=100, 200) hydrogen storage alloys were synthesized by mechanical milling. The effects of Ni content and milling time on hydrogen storage thermodynamics and dynamics of the alloys were systematically investigated. The gaseous hydrogen absorption and desorption properties were investigated by Sieverts apparatus and differential scanning calorimeter connected with a H_2 detector. Results show that increasing Ni content significantly improves hydrogen absorption and desorption kinetics of the alloys. Furthermore,varying milling time has an obvious effect on the hydrogen storage properties of the alloys. Hydrogen absorption saturation ratio(R^a_(10); a ratio of the hydrogen absorption capacity in 10 min to the saturated hydrogen absorption capacity) of the alloys obtains the maximum value with varying milling time. Hydrogen desorption ratio(R^d_(20), a ratio of the hydrogen desorption capacity in 20 min to the saturated hydrogen absorption capacity) of the alloys always increases with extending milling time. The improved hydrogen desorption kinetics of the alloys are considered to be ascribed to the decreased hydrogen desorption activation energy caused by increasing Ni content and milling time. 展开更多
关键词 NdMg12 alloy Hydrogen storage Mechanical milling Activation energy Kinetics
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Hydrogen Storage Kinetics of Nanocrystalline and Amorphous LaMg_(12)-Type Alloy–Ni Composites Synthesized by Mechanical Milling 被引量:1
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作者 Yanghuan Zhang Baowei Li +4 位作者 Huiping Ren Tai Yang Shihai Guo Yan Qi Dongliang Zhao 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第3期218-225,共8页
The nanocrystalline and amorphous LaMg11Ni + x wt% Ni (x = 100, 200) composites were synthesized by the mechanical milling, and their gaseous and electrochemical hydrogen storage kinetics performance were systemati... The nanocrystalline and amorphous LaMg11Ni + x wt% Ni (x = 100, 200) composites were synthesized by the mechanical milling, and their gaseous and electrochemical hydrogen storage kinetics performance were systematically investigated, The results indicate that the as-milled composites exhibit excellent hydrogen storage kinetic performances, and increasing Ni content significantly facilitates the improvement of the hydrogen storage kinetics properties of the composites. The gaseous and electrochemical hydrogen storage kinetics of the composites reaches a maximum value with the variation of milling time. Increasing Ni content and milling time both make the hydrogen desorption activation energy lower, which are responsible for the enhancement in the hydrogen storage kinetics properties of the composites. The diffusion coefficient of hydrogen atom and activation enthalpy of charge transfer on the surface of the as-milled composites were also calculated, which are considered to be the dominated factors for the electrochemical high rate discharge ability. 展开更多
关键词 LaMg12 alloy Mechanical milling Activation energy Hydrogen storage kinetics
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Hydrogen storage thermodynamic and kinetic characteristics of PrMg12-type alloys synthesized by mechanical milling 被引量:1
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作者 Jin-liang Gao Yan Qi +3 位作者 Ya-qin Li Hong-wei Shang Dong-liang Zhao Yang-huan Zhang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2017年第2期198-205,共8页
To improve the hydrogen storage performance of PrMg12-type alloys, Ni was adopted to replace partially Mg in the alloys. The PrMgllNi+x wt.% Ni (x=100, 200) alloys were prepared via mechanical milling. The phase st... To improve the hydrogen storage performance of PrMg12-type alloys, Ni was adopted to replace partially Mg in the alloys. The PrMgllNi+x wt.% Ni (x=100, 200) alloys were prepared via mechanical milling. The phase structures and morphology of the experimental alloys were in vestigated by X-ray diffraction and transmission electron microscopy. The results show that increasing milling time and Ni content accelerate the formation of nanocrystalline and amorphous structure. The gaseous hydrogen storage properties of the experimental alloys were determined by differential scanning calorimetry (DSC) and Sievert apparatus. In addition, increasing milling time makes the hydrogenation rates of the alloys augment firstly and decline subsequently and the dehydrogenation rate always increases. The maximum capacity is 5. 572 wt. % for the x = 100 alloy and 5. 829 wt. % for the x = 200 alloy, respectively. The enthalpy change ( △H ), entropy change (△S) and the dehydrogenation activation energy (Exde) markedly lower with increasing the milling time and the Ni content due to the generation of nanocrystalline and amorphous structure. 展开更多
关键词 PrMg12 alloy Mechanical milling Activation energy Hydrogen storage dynamics Thermodynamics
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Theoretical Study of the Radical Scavenging Activity of Shikonin and Its Derivatives
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作者 靳瑞岌 李杰 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2012年第1期84-90,共7页
A series of shikonin derivatives have been designed and their radical scavenging activity has been characterized by the B3LYP/6-31 +G(d) approach. The hydrogen bond properties of the studied structures were investi... A series of shikonin derivatives have been designed and their radical scavenging activity has been characterized by the B3LYP/6-31 +G(d) approach. The hydrogen bond properties of the studied structures were investigated using the atoms in molecules (AIM) theory. The calculated results reveal that the hydrogen bond is important for good scavenging activity. The introduction of electron-drawing (electron-donating) groups increases (decreases) the scavenging activities of radical and radical cations of shikonin derivatives. Shikonin derivatives appear to be good candidates for the single-electron-transfer mechanism, particularly for -N(CH3)2 derivative. Taking this system as an example, we present an efficient method for the investigation of radical scavenging activity from theoretical point of view. With the current work, we hope to highlight the radical scavenging activity of hydroxynaphtho- quinones derivatives and stimulate the interest for further studies and exploitation in pharmaceutical industry. 展开更多
关键词 shikonin derivatives radical scavenging activity hydrogen atom transfer mechanism single electrontransfer mechanism atoms in molecules theory (AIM)
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Phase Stability in Mechanically Alloyed Mg–Ni System Studied by Experiments and Thermodynamic Calculations
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作者 Mohammad Hossein Enayati Fathallah Karimzadeh +1 位作者 Soheil Sabooni Majid Jafari 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2015年第8期1002-1007,共6页
In this study, microstructural evolution of Mg–Ni alloy during mechanical alloying(MA) was investigated.Also, a thermodynamic approach was utilized to predict the most stable phases formed in Mg–Ni alloy after MA.... In this study, microstructural evolution of Mg–Ni alloy during mechanical alloying(MA) was investigated.Also, a thermodynamic approach was utilized to predict the most stable phases formed in Mg–Ni alloy after MA. The phase composition and microstructural properties of Mg–Ni alloy were assessed by X-ray diffractometry, high-resolution field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results showed that ball milling of magnesium and nickel powder mixture for 70 h yields nanostructural Mg2Ni compound with an average grain size of ~20 nm. Thermodynamic calculations revealed that in the composition ranges of 0.0 / XMg/ 0.03(at.%)and 0.97 / XMg/ 1, there is no driving force for amorphous phase formation. In the composition range of 0.07 / XMg/ 0.93, the change of Gibbs free energy for amorphous phase formation was more negative than solid solution.While for XMg= 0.66(nominal composition of Mg2Ni intermetallic phase), the change of Gibbs free energy for intermetallic phase was found to be more negative than both amorphous and solid solution phases indicating that Mg2Ni intermetallic compound is the most stable phase, in agreement with the experimental observations. 展开更多
关键词 Mechanical alloying Nanocrystalline Hydrogen storage material Mg2Ni Thermodynamics
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