期刊文献+
共找到525篇文章
< 1 2 27 >
每页显示 20 50 100
Cu-based materials for electrocatalytic CO_(2) to alcohols:Reaction mechanism,catalyst categories,and regulation strategies
1
作者 Yaru Lei Yaxin Niu +8 位作者 Xiaolong Tang Xiangtao Yu Xiubing Huang Xiaoqiu Lin Honghong Yi Shunzheng Zhao Jiaying Jiang Jiyue Zhang Fengyu Gao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第10期593-611,I0013,共20页
Electrocatalytic CO_(2) reduction reaction(CO_(2)RR)technology,which enables carbon capture storage and resource utilization by reducing CO_(2) to valuable chemicals or fuels,has become a global research hotspot in re... Electrocatalytic CO_(2) reduction reaction(CO_(2)RR)technology,which enables carbon capture storage and resource utilization by reducing CO_(2) to valuable chemicals or fuels,has become a global research hotspot in recent decades.Among the many products of CO_(2)RR(carbon monoxide,acids,aldehydes and alcohols,olefins,etc.),alcohols(methanol,ethanol,propanol,etc.)have a higher market value and energy density,but it is also more difficult to produce.Copper is known to be effective in catalyzing CO_(2) to high valueadded alcohols,but with poor selectivity.The progress of Cu-based catalysts for the selective generation of alcohols,including copper oxides,bimetals,single atoms and composites is reviewed.Meanwhile,to improve Cu-based catalyst activity and modulate product selectivity,the modulation strategies are straighten out,including morphological regulation,crystalline surface,oxidation state,as well as elemental doping and defect engineering.Based on the research progress of electrocatalytic CO_(2) reduction for alcohol production on Cu-based materials,the reaction pathways and the key intermediates of the electrocatalytic CO_(2)RR to methanol,ethanol and propanol are summarized.Finally,the problems of traditional electrocatalytic CO_(2)RR are introduced,and the future applications of machine learning and theoretical calculations are prospected.An in-depth discussion and a comprehensive review of the reaction mechanism,catalyst types and regulation strategies were carried out with a view to promoting the development of electrocatalytic CO_(2)RR to alcohols. 展开更多
关键词 Electrocatalytic CO_(2)RR Cu-based catalyst ALCOHOLS reaction mechanism Regulation strategies
下载PDF
In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction
2
作者 Andi Haryanto Kyounghoon Jung +1 位作者 Chan Woo Lee Dong-Wan Kim 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第3期632-651,I0014,共21页
Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy future.Computational methods have been widely use... Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy future.Computational methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic insights.In this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the HER.In addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during HER.These spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER. 展开更多
关键词 Hydrogen evolution reaction Infrared spectroscopy Raman spectroscopy X-ray absorption spectroscopy reaction mechanism
下载PDF
Study on trifluoromethanesulfonic acid-promoted synthesis of daidzein: Process optimization and reaction mechanism
3
作者 Hai Cao Haibin Yang +3 位作者 Yanxiong Fang Yuandi Zeng Xiaolan Cai Jingjing Ma 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第7期132-139,共8页
Daidzein has been widely used in pharmaceuticals,nutraceuticals,cosmetics,feed additives,etc.Its preparation process and related reaction mechanism need to be further investigated.A cost-effective process for synthesi... Daidzein has been widely used in pharmaceuticals,nutraceuticals,cosmetics,feed additives,etc.Its preparation process and related reaction mechanism need to be further investigated.A cost-effective process for synthesizing daidzein was developed in this work.In this article,a two-step synthesis of daidzein(Friedel–Crafts acylation and[5+1]cyclization)was developed via the employment of trifluoromethanesulfonic acid(TfOH)as an effective promoting reagent.The effect of reaction conditions such as solvent,the amount of TfOH,reaction temperature,and reactant ratio on the conversion rate and the yield of the reaction,respectively,was systematically investigated,and daidzein was obtained in 74.0%isolated yield under optimal conditions.Due to the facilitating effect of TfOH,the Friedel–Crafts acylation was completed within 10 min at 90℃ and the[5+1]cyclization was completed within 180 min at 25℃.In addition,a possible reaction mechanism for this process was proposed.The results of the study may provide useful guidance for industrial production of daidzein on a large scale. 展开更多
关键词 SYNTHESIS Optimal design Chemical processes reaction mechanism
下载PDF
Study of the reaction mechanism for preparing powdered activated coke with SO_(2)adsorption capability via one-step rapid activation method under flue gas atmosphere
4
作者 Binxuan Zhou Jingcai Chang +5 位作者 Jun Li Jinglan Hong Tao Wang Liqiang Zhang Ping Zhou Chunyuan Ma 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第1期158-168,共11页
In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction m... In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction mechanism is summarized.Results indicate that the reaction process of this method can be divided into three stages:stage I is the rapid release of volatiles and the rapid consumption of O_(2),primarily occurring within a reaction time range of 0-0.5 s;stage II is mainly the continuous release and diffusion of volatiles,which is the carbonization and activation coupling reaction stage,and the carbonization process is the main in this stage.This stage mainly occurs at the reaction time range of 0.5 -2.0 s when SL-coal is used as material,and that is 0.5-3.0 s when JJ-coal is used as material;stage III is mainly the activation stage,during which activated components diffuse to both the surface and interior of particles.This stage mainly involves the reaction stage of CO_(2)and H2O(g)activation,and it mainly occurs at the reaction time range of 2.0-4.0 s when SL-coal is used as material,and that is 3.0-4.0 s when JJ-coal is used as material.Besides,the main function of the first two stages is to provide more diffusion channels and contact surfaces/activation sites for the diffusion and activation of the activated components in the third stage.Mastering the reaction mechanism would serve as a crucial reference and foundation for designing the structure,size of the reactor,and optimal positioning of the activator nozzle in PAC preparation. 展开更多
关键词 reaction mechanism Powdered activated coke preparation SO_(2)adsorption One-step rapid activation Flue gas atmosphere
下载PDF
The reaction mechanism and interfacial crystallization of Al nanoparticle-embedded Ni under shock loading
5
作者 Yifan Xie Jian-Li Shao +1 位作者 Rui Liu Pengwan Chen 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第3期114-124,共11页
The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nan... The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nanoparticle,interfacial crystallization and dissolution are the main characteristics.The reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following dissolution.The reaction rate increases with the decrease of particle diameter,however,the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our simulations.Meanwhile,we found a negative exponential growth in the fraction of crystallized Al atoms,and the crystallinity of B2-NiAl(up to 20%)is positively correlated with the specific surface area of Al particle.This can be attributed to the formation mechanism of B2-NiAl by structural evolution of finite mixing layer near the collapsed interface.For shock melting of both Al particle and Ni matrix,the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal jet.In addition,the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement,which results in an almost constant reaction rate similar to the mechanical mixing process. 展开更多
关键词 Shock-induced reaction Molecular dynamics simulations Interfacial crystallization reaction mechanism
下载PDF
Recent Advances in Transition Metal-Based Catalysts for Electrocatalytic Nitrate Reduction Reaction
6
作者 LUO Hongxia CHEN Jun YANG Jianping 《Journal of Donghua University(English Edition)》 CAS 2024年第4期333-348,共16页
The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalyti... The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalytic nitrate reduction reaction(eNO_(3)RR)has been widely studied for its advantages of being eco-friendly,easy to operate,and controllable under environmental conditions with renewable energy as the driving force.Transition metal-based catalysts(TMCs)have been widely used in electrocatalysis due to their abundant reserves,low costs,easy-to-regulate electronic structure and considerable electrochemical activity.In addition,TMCs have been extensively studied in terms of the kinetics of the nitrate reduction reaction,the moderate adsorption energy of nitrogen-containing species and the active hydrogen supply capacity.Based on this,this review firstly discusses the mechanism as well as analyzes the two main reduction products(N_(2)and NH_(3))of eNO_(3)RR,and reveals the basic guidelines for the design of efficient nitrate catalysts from the perspective of the reaction mechanism.Secondly,this review mainly focuses on the recent advances in the direction of eNO_(3RR)with four types of TMCs,Fe,Co,Ni and Cu,and unveils the interfacial modulation strategies of Fe,Co,Ni and Cu catalysts for the activity,reaction pathway and stability.Finally,reasonable suggestions and opportunities are proposed for the challenges and future development of eNO_(3)RR.This review provides far-reaching implications for exploring cost-effective TMCs to replace high-cost noble metal catalysts(NMCs)for eNO_(3)RR. 展开更多
关键词 electrocatalysis nitrate reduction reaction transition metal-based catalyst(TMC) reaction mechanism nitrogen cycle
下载PDF
Insights into kinetics and reaction mechanism of acid-catalyzed transesterification synthesis of diethyl oxalate
7
作者 Naiwen Zhang Rui Xia +4 位作者 Siyu Wan Xinyang Xiong Jinggang Zhao Jun Zhou Lei Shi 《Resources Chemicals and Materials》 2024年第1期93-101,共9页
The catalytic performance of different acidic catalysts for diethyl oxalate synthesis from the one-step transesterification of dimethyl oxalate and ethanol was evaluated.The effects of different factors(e.g.,acidity,e... The catalytic performance of different acidic catalysts for diethyl oxalate synthesis from the one-step transesterification of dimethyl oxalate and ethanol was evaluated.The effects of different factors(e.g.,acidity,electron accepting capacity,cations type and crystalline water)on the catalytic activity of acidic catalysts were investigated respectively.It was proposed and confirmed that the transesterification reaction catalyzed by a Lewis acid(FeCl3)and a Bronsted acid(H2SO4)follows a first-order kinetic reaction process.In addition,the Lewis acid-catalyzed transesterification processes with different ester structures were used to further explore and understand the speculated reaction mechanism.This work enriches the theoretical understanding of acid-catalyzed transesterification reactions and is of great significance for the development of highly active catalysts for diethyl oxalate synthesis,diminishing the industrial production cost of diethyl oxalate,and developing downstream bulk or high-value-added industrial products. 展开更多
关键词 Diethyl oxalate TRANSESTERIFICATION KINETICS Acidic catalyst reaction mechanism
下载PDF
Recent progress in research and design concepts for the characterization,testing,and photocatalysts for nitrogen reduction reaction 被引量:3
8
作者 Benteng Sun Shucao Lu +2 位作者 Yeye Qian Xiaoli Zhang Jian Tian 《Carbon Energy》 SCIE CSCD 2023年第3期19-74,共56页
The reduction of molecular nitrogen(N_(2))to ammonia(NH_(3))under mild conditions is one of the most promising studies in the energy field due to the important role of NH_(3)in modern industry,production,and life.The ... The reduction of molecular nitrogen(N_(2))to ammonia(NH_(3))under mild conditions is one of the most promising studies in the energy field due to the important role of NH_(3)in modern industry,production,and life.The photocatalytic reduction of N_(2)is expected to achieve clean and sustainable NH_(3)production by using clean solar energy.To date,the new photocatalysts for photocatalytic reduction of N_(2)to NH_(3)at room temperature and atmospheric pressure have not been fully developed.The major challenge is to achieve high light-absorption efficiency,conversion efficiency,and stability of photocatalysts.Herein,the methods for measuring produced NH_(3)are compared,and the problems related to possible NH_(3)pollution in photocatalytic systems are mentioned to provide accurate ideas for measuring photocatalytic efficiency.The recent progress of nitrogen reduction reaction(NRR)photocatalysts at ambient temperature and pressure is summarized by introducing charge transfer,migration,and separation in photocatalytic NRR,which provides a guidance for the selection of future photocatalyst.More importantly,we introduce the latest research strategies of photocatalysts in detail,which can guide the preparation and design of photocatalysts with high NRR activity. 展开更多
关键词 nitrogen reduction reaction PHOTOCATALYSTS produced NH 3 measuring methods reaction mechanism research strategy
下载PDF
For more and purer hydrogen-the progress and challenges in water gas shift reaction 被引量:2
9
作者 Limin Zhou Yanyan Liu +8 位作者 Shuling Liu Huanhuan Zhang Xianli Wu Ruofan Shen Tao Liu Jie Gao Kang Sun Baojun Li Jianchun Jiang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第8期363-396,I0010,共35页
The water gas shift(WGS) reaction is a standard reaction that is widely used in industrial hydrogen production and removal of carbon monoxide. The improved catalytic performance of WGS reaction also contributes to amm... The water gas shift(WGS) reaction is a standard reaction that is widely used in industrial hydrogen production and removal of carbon monoxide. The improved catalytic performance of WGS reaction also contributes to ammonia synthesis and other reactions. Advanced catalysts have been developed for both high and low-temperature reactions and are widely used in industry. In recent years, supported metal nanoparticle catalysts have been researched due to their high metal utilization. Low-temperature catalysts have shown promising results, including high selectivity, high shift rates, and higher activity potential. Additionally, significant progress has been made in removing trace CO through the redox reaction in electrolytic cell. This paper reviews the development of WGS reaction catalysts, including the reaction mechanism, catalyst design, and innovative research methods. The catalyst plays a crucial role in the WGS reaction, and this paper provides an instant of catalyst design under different conditions. The progress of catalysts is closely related to the development of advanced characterization techniques.Furthermore, modifying the catalyst surface to enhance activity and significantly increase reaction kinetics is a current research direction. This review goals to stimulate a better understanding of catalyst design, performance optimization, and driving mechanisms, leading to further progress in this field. 展开更多
关键词 Water gas shift reaction Hydrogen production Heterogeneous catalysis reaction Mechanism Single atomic catalysts
下载PDF
Exploration of optimal reaction conditions on lactic acid production from glucose photoreforming over carbon nitride 被引量:1
10
作者 Heng Zhao Xiao Wang +6 位作者 Xingxing Wu Jiu Wang Na Zhong Ali Seifitokaldani Stephen Larter Md Golam Kibria Jinguang Hu 《Resources Chemicals and Materials》 2023年第2期111-116,共6页
Biomass valorization by photoreforming approach provides a promising and alternative strategy to generate value-added chemicals and fuels.In this work,we demonstrate the selective production of lactic acid from glu-co... Biomass valorization by photoreforming approach provides a promising and alternative strategy to generate value-added chemicals and fuels.In this work,we demonstrate the selective production of lactic acid from glu-cose photoreforming over pristine graphitic carbon nitride(g-C_(3) N_(4))photocatalyst.Control experiments screen the best condition for the highest yield of lactic acid,including modulating pH,catalyst loading,and reaction time.100%glucose conversion is achieved along with almost 100%lactic acid yield under the optimized con-dition.Density functional theory(DFT)calculations reveal that the rate-determining step(RDS)of the overall reaction on g-C_(3) N_(4) is the conversion of pyruvaldehyde,where an electron transfer takes place.This present work provides experimental insights and theoretical understanding for selective lactic acid production from biomass photoreforming. 展开更多
关键词 Lactic acid Glucose photoreforming Carbon nitride DFT reaction mechanism
下载PDF
In Situ Reaction Strengthening and Toughening of B_(4)C/TiSi_(2)Ceramics
11
作者 夏涛 涂晓诗 +2 位作者 张帆 ZHANG Jinyong REN Lin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第1期12-19,共8页
B_(4)C-SiC-TiB_(2)ceramics were prepared by in situ reactive hot-pressing sintering with TiSi_(2)as an additive.The reaction pathways of TiSi_(2)and B_(4)C were investigated.The sintering was found to be a multistep p... B_(4)C-SiC-TiB_(2)ceramics were prepared by in situ reactive hot-pressing sintering with TiSi_(2)as an additive.The reaction pathways of TiSi_(2)and B_(4)C were investigated.The sintering was found to be a multistep process.The reaction started at approximately 1000℃,and TiB_(2)was formed first.Part of Si and C started to react at 1300℃,and the unreacted Si melted at 1400℃to form a liquid phase.TiSi_(2)predominantly affected the intermediate sintering process of B_(4)C and increased the sintering rate.Due to the unique reaction process of TiSi_(2)and B_(4)C,a large number of aggregates composed of SiC and TiB_(2)were generated.The results showed that composite ceramics with the optimal flexural strength of 807 MPa,fracture toughness of 3.2 MPa·m1/2,and hardness of 32 GPa,were obtained when the TiSi_(2)content was 10 wt%. 展开更多
关键词 in situ reaction hot pressing sintering TiSi_(2) B_(4)C composite ceramics reaction mechanism
下载PDF
Mechanism Study of BF_(3)/n-Butanol-catalyzed 1-Decene Oligomerization Reaction
12
作者 He Leilei Su Shuo +2 位作者 Zhao Yi Xu Bing Long Jun 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第2期74-80,共7页
The active catalysts of the BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization reaction,as well as the distribution of the reaction products,was investigated by molecular simulation.The calculation results show ... The active catalysts of the BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization reaction,as well as the distribution of the reaction products,was investigated by molecular simulation.The calculation results show that(BF_(3))_(2)·n-C_(4)H_(9)OH catalyzes the 1-decene oligomerization reaction with higher activity compared to BF_(3)·n-C_(4)H_(9)OH,which is the most catalytically active substance in the BF_(3)/n-C_(4)H_(9)OH catalyst system.The reaction energy barriers and heats of reaction of chain initiation,chain growth,and chain termination in BF_(3)/n-C_(4)H_(9)OH-catalyzed 1-decene oligomerization are calculated to reveal the product distribution.The calculation results show that the contents of the oligomerization reaction products in descending order are trimer,tetramer,pentamer,and dimer.The calculated results were consistent with the experimentally obtained product distribution. 展开更多
关键词 poly-α-olefin synthetic base oil oligomerization reaction reaction mechanism boron trifluoride
下载PDF
Promotional roles of ZrO_2 and WO_3 in V_2O_5-WO_3/TiO_2-ZrO_2 catalysts for NO_x reduction by NH_3:Catalytic performance,morphology,and reaction mechanism 被引量:8
13
作者 张亚平 王龙飞 +4 位作者 李娟 张会岩 徐海涛 肖睿 杨林军 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第11期1918-1930,共13页
V2O5/TiO2-ZrO2 catalysts containing various amounts of WO3 were synthesized.The catalyst morphologies,catalytic performances,and reaction mechanisms in the selective catalytic reduction of NOx by NH3 were investigated... V2O5/TiO2-ZrO2 catalysts containing various amounts of WO3 were synthesized.The catalyst morphologies,catalytic performances,and reaction mechanisms in the selective catalytic reduction of NOx by NH3 were investigated using in situ diffuse-reflectance infrared Fourier-transform spectroscopy,temperature-programmed reduction(TPR),X-ray diffraction,and the Brunauer-Emmett-Teller(BET) method.The BET surface area of the triple oxides increased with increasing ZrO2 doping but gradually decreased with increasing WO3 loading.Addition of sufficient WO3 helped to stabilize the pore structure and the combination of WO3 and ZrO2 improved dispersion of all the metal oxides.The mechanisms of reactions using V2O5-9%WO3/TiO2-ZrO2 and V2O5-9%WO3/TiO2were compared by using either a single or mixed gas feed and various pretreatments.The results suggest that both reactions followed the Eley-Ridel mechanism;however,the dominant acid sites,which depended on the addition of WO3 or ZrO2,determined the pathways for NOx reduction,and involved[NH4^+-NO-Bronsted acid site]^* and[NH2-NO-Lewis acid site]^* intermediates,respectively.NH3-TPR and H2-TPR showed that the metal oxides in the catalysts were not reduced by NH3 and O2did not reoxidize the catalyst surfaces but participated in the formation of H2O and NO2. 展开更多
关键词 ZIRCONIA Tungsten oxide Selective catalytic reduction by ammonia In situ infrared diffuse-reflectance Fourier-transform spectroscopy reaction mechanism
下载PDF
Mechanism for thermite reactions of aluminum/iron-oxide nanocomposites based on residue analysis 被引量:7
14
作者 王毅 宋小兰 +4 位作者 姜炜 邓国栋 郭效德 刘宏英 李凤生 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第1期263-270,共8页
Sol-gel method was employed to combine Al and iron-oxide to form nanocomposites (nano-Al/xero-Fe2O3 and micro-Al/xero-Fe2O3). SEM, EDS and XRD analyses were used to characterize the nanocomposites and the results in... Sol-gel method was employed to combine Al and iron-oxide to form nanocomposites (nano-Al/xero-Fe2O3 and micro-Al/xero-Fe2O3). SEM, EDS and XRD analyses were used to characterize the nanocomposites and the results indicated that nano-Al and micro-Al were compactly wrapped by amorphous iron-oxide nanoparticles (about 20 nm), respectively. The iron-oxide showed the mass ratio of Fe to O as similar as that in Fe2O3. Thermal analyses were performed on two nanocomposites, and four simple mixtures (nano-Al+xero-Fe2O3, nano-Al+micro-Fe2O3, micro-Al+xero-Fe2O3, and micro-Al+micro-Fe2O3) were also analyzed. There were not apparent distinctions in the reactions of thermites fueled by nano-Al. For thermites fueled by micro-Al, the DSC peak temperatures of micro-Al/Xero-Fe2O3 were advanced by 68.1 ℃ and 76.8 ℃ compared with micro-Al+xero-Fe2O3 and micro-Al+micro-Fe2O3, respectively. Four thermites, namely, nano-Al/xero-Fe2O3, nano-Al+micro-Fe2O3, micro-Al/xero-Fe2O3, and micro-Al+micro-Fe2O3, were heated from ambient temperature to 1020 ℃, during which the products at 660 ℃ and 1020 ℃ were collected and analyzed by XRD. Crystals of Fe, FeAl2O4, Fe3O4,α-Fe2O3, Al,γ-Fe2O3, Al2.667O4, FeO andα-Al2O3 were indexed in XRD patterns. For each thermite, according to the specific products, the possible equations were given. Based on the principle of the minimum free energy, the most reasonable equations were inferred from the possible reactions. 展开更多
关键词 AL AL NANOCOMPOSITES thermite reaction reaction mechanism
下载PDF
Reaction mechanisms of low-grade molybdenum concentrate during calcification roasting process 被引量:6
15
作者 甘敏 范晓慧 +6 位作者 陈许玲 吴程骞 季志云 王送荣 汪国靖 邱冠周 姜涛 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第11期3015-3023,共9页
The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. T... The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The resultsshow that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidationtemperature of MoS2 is 450℃, while the formation of CaMoO4 and CaSO4 occurs above 500℃. The whole calcification reactionsare nearly completed between 600 and 650℃. However, raising the temperature further helps for the formation of CaMoO4 but isdisadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows theorder: Ca(OH)2〉CaO〉CaCO3. With increasing the dosage of Ca(OH)2, the molybdenum retention rate and sulfur-fixing rate rise, butexcessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca(OH)2 to molybdenumconcentrate is 1:1. When roasted at 650 ℃ for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grademolybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% withcalcines being leached by sulphuric acid. 展开更多
关键词 molybdenum concentrate calcification roasting reaction mechanism thermodynamic analysis phase transformation
下载PDF
Reaction mechanism of preparation of titanium by electro-deoxidation in molten salt 被引量:9
16
作者 王斌 刘奎仁 陈建设 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第10期2327-2331,共5页
The electro-deoxidation of TiO2 was investigated in molten CaCl2.Back electromotive force measurements,constant voltage electrolytic experiments,contrast experiments of different cathodes,and cyclic voltammograms were... The electro-deoxidation of TiO2 was investigated in molten CaCl2.Back electromotive force measurements,constant voltage electrolytic experiments,contrast experiments of different cathodes,and cyclic voltammograms were carried out for solving the puzzle of reduction mechanism.The results showed that the reduction process proceeded step by step.TiO2 was first reduced to Ti3O5 or Ti2O3,and then further reduced to Ti3O,Ti2O,TiO and Ti.In addition,direct electrochemical reduction of titanium dioxide was the primary cathodic reaction;meanwhile,some calciothermic reduction reactions also happened at the cathode.Cyclic voltammograms of solid titanium dioxide and molybdenum wire in molten salts with different compositions were also studied. 展开更多
关键词 TITANIUM ELECTRO-DEOXIDATION reaction mechanism molten salt
下载PDF
Engineering g-C_(3)N_(4)based materials for advanced photocatalysis:Recent advances 被引量:1
17
作者 Xin-Lian Song Lei Chen +2 位作者 Li-Jiao Gao Jin-Tao Ren Zhong-Yong Yuan 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第2期166-197,共32页
Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental remediation.The outstanding electronic structure and physicochemical properti... Photocatalysis driven by abundant yet intermittent solar energy has considerable potential in renewable energy generation and environmental remediation.The outstanding electronic structure and physicochemical properties of graphitic carbon nitride(g-C_(3)N_(4)),together with unique metal-free characteristic,make them ideal candidates for advanced photocatalysts construction.This review summarizes the up-to-date advances on g-C_(3)N_(4)based photocatalysts from ingenious-design strategies and diversified photocatalytic applications.Notably,the advantages,fabrication methods and limitations of each design strategy are systemically analyzed.In order to deeply comprehend the inner connection of theory–structure–performance upon g-C_(3)N_(4)based photocatalysts,structure/composition designs,corresponding photocatalytic activities and reaction mechanisms are jointly discussed,associated with introducing their photocatalytic applications toward water splitting,carbon dioxide/nitrogen reduction and pollutants degradation,etc.Finally,the current challenges and future perspectives for g-C_(3)N_(4)based materials for photocatalysis are briefly proposed.These design strategies and limitations are also instructive for constructing g-C_(3)N_(4) based materials in other energy and environment-related applications. 展开更多
关键词 Graphitic carbon nitride g-C_(3)N_(4) Design strategies PHOTOCATALYSIS PHOTOCATALYSTS reaction mechanism
下载PDF
High-rate electrochemical H_(2)O_(2) production over multimetallic atom catalysts under acidic–neutral conditions 被引量:1
18
作者 Yueyu Tong Jiaxin Liu +5 位作者 Bing-Jian Su Jenh-Yih Juang Feng Hou Lichang Yin Shi Xue Dou Ji Liang 《Carbon Energy》 SCIE EI CAS CSCD 2024年第1期44-62,共19页
Hydrogen peroxide(H_(2)O_(2))production by the electrochemical 2-electron oxygen reduction reaction(2e−ORR)is a promising alternative to the energy-intensive anthraquinone process,and single-atom electrocatalysts show... Hydrogen peroxide(H_(2)O_(2))production by the electrochemical 2-electron oxygen reduction reaction(2e−ORR)is a promising alternative to the energy-intensive anthraquinone process,and single-atom electrocatalysts show the unique capability of high selectivity toward 2e−ORR against the 4e−one.The extremely low surface density of the single-atom sites and the inflexibility in manipulating their geometric/electronic configurations,however,compromise the H_(2)O_(2) yield and impede further performance enhancement.Herein,we construct a family of multiatom catalysts(MACs),on which two or three single atoms are closely coordinated to form high-density active sites that are versatile in their atomic configurations for optimal adsorption of essential*OOH species.Among them,the Cox–Ni MAC presents excellent electrocatalytic performance for 2e−ORR,in terms of its exceptionally high H_(2)O_(2) yield in acidic electrolytes(28.96 mol L^(−1) gcat.^(−1) h^(−1))and high selectivity under acidic to neutral conditions in a wide potential region(>80%,0–0.7 V).Operando X-ray absorption and density functional theory analyses jointly unveil its unique trimetallic Co2NiN8 configuration,which efficiently induces an appropriate Ni–d orbital filling and modulates the*OOH adsorption,together boosting the electrocatalytic 2e−ORR capability.This work thus provides a new MAC strategy for tuning the geometric/electronic structure of active sites for 2e−ORR and other potential electrochemical processes. 展开更多
关键词 hydrogen peroxide production multiatom catalysts operando X-ray adsorption spectrum reaction mechanism tendency structure-property relation
下载PDF
Theoretical investigations on CO oxidation reaction catalyzed by gold nanoparticles 被引量:2
19
作者 孙科举 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第10期1608-1618,共11页
It is crucial to understand the mechanism of low temperature CO oxidation reaction catalyzed by gold nanoparticles so as to find out the origin of the high catalytic reactivity and extend the indus‐trialization appli... It is crucial to understand the mechanism of low temperature CO oxidation reaction catalyzed by gold nanoparticles so as to find out the origin of the high catalytic reactivity and extend the indus‐trialization applications of nano gold catalysts. In this work, some theoretical works on CO adsorp‐tion, O2 adsorption, atomic oxygen adsorption, formation of surface gold oxide films, reaction mechanisms of CO oxidation involving O2 reaction with CO and O2 dissociation before reacting with CO on gold surfaces and Au/metal oxide were summarized, and the influences of coordination number, charge transfer and relativity of gold on CO oxidation reaction were briefly reviewed. It was found that CO reaction mechanism depended on the systems with or without oxide and the strong relativistic effects might play an important role in CO oxidation reaction on gold catalysts. In particular, the relativistic effects are related to the unique behaviors of CO adsorption, O adsorption, O2 activation on gold surfaces, effects of coordination number and the wide gap between the chem‐ical inertness of bulk gold and high catalytic activity of nano gold. The present work helps us to understand the CO oxidation reaction mechanism on gold catalysts and the influence of relativistic effects on gold catalysis. 展开更多
关键词 Carbon monoxide oxidation reaction Gold nanoparticle reaction mechanism Theoretical calculation Relativistic effect
下载PDF
Recent Advances in Mechanistic Understanding of Metal-Free Carbon Thermocatalysis and Electrocatalysis with Model Molecules
20
作者 Wei Guo Linhui Yu +2 位作者 Ling Tang Yan Wan Yangming Lin 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第7期74-97,共24页
Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and sustainability.Ov... Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and sustainability.Over the past decade,well-designed carbon catalysts with tunable structures and heteroatom groups coupled with various characterization techniques have proposed numerous reaction mechanisms.However,active sites,key intermediate species,precise structure-activity relationships and dynamic evolution processes of carbon catalysts are still rife with controversies due to the monotony and limitation of used experimental methods.In this Review,we sum-marize the extensive efforts on model catalysts since the 2000s,particularly in the past decade,to overcome the influences of material and structure limitations in metal-free carbon catalysis.Using both nanomolecule model and bulk model,the real contribution of each alien species,defect and edge configuration to a series of fundamentally important reactions,such as thermocatalytic reactions,electrocatalytic reactions,were systematically studied.Combined with in situ techniques,isotope labeling and size control,the detailed reaction mechanisms,the precise 2D structure-activity relationships and the rate-determining steps were revealed at a molecular level.Furthermore,the outlook of model carbon catalysis has also been proposed in this work. 展开更多
关键词 Metal-free carbon catalysts Model catalyst ELECTROCATALYSIS Active site reaction mechanisms
下载PDF
上一页 1 2 27 下一页 到第
使用帮助 返回顶部