The triple bond in N_(2)has an extremely high bond energy and is thus difficult to break.N_(2)is commonly converted into NH3 artificially via the Haber-Bosch process,and NH_(3)can be utilized to produce other nitrogen...The triple bond in N_(2)has an extremely high bond energy and is thus difficult to break.N_(2)is commonly converted into NH3 artificially via the Haber-Bosch process,and NH_(3)can be utilized to produce other nitrogen-containing chemicals.Here,we developed an electron catalyzed method to directly fix N_(2)into azos,by pushing and pulling the electron into and from the aromatic halide with the cyclic voltammetry method.The round-trip journey of electron can successfully weaken the triple bond in N_(2)through the electron pushing-induced aryl radical via a“brick trowel”transition state,and then produce the diazonium ions by pulling the electron out from the diazo radical intermediate.Different azos can be synthesized with this developed electron catalyzed approach.This approach provides a novel concept and practical route for the fixation of N_(2)at atmospheric pressure into chemical products valuable for industrial and commercial applications.展开更多
The technology for green and macro-conversion of solid waste biomass to prepare high-quality activated carbon demands urgent development.This study proposes a technique for synthesizing carbon adsorbents using trace K...The technology for green and macro-conversion of solid waste biomass to prepare high-quality activated carbon demands urgent development.This study proposes a technique for synthesizing carbon adsorbents using trace KOH-catalyzed CO_(2) activation.Comprehensive investigations were conducted on three aspects:physicochemical structure evolution of biochar,mechanistic understanding of trace KOH-facilitated CO_(2) activation processes,and application characteristics for CO_(2) adsorption.Results demonstrate that biochar activated by trace KOH(<10%)and CO_(2) achieves comparable specific surface area(1244.09 m^(2)/g)to that obtained with 100%KOH activation(1425.10 m^(2)/g).The pore structure characteristics(specific surface area and pore volume)are governed by CO and CH4 generated through K-salt catalyzed reactions between CO_(2) and biochar.The optimal CO_(2) adsorption capacities of KBC adsorbent reached 4.70 mmol/g(0℃)and 7.25 mmol/g(25℃),representing the maximum values among comparable carbon adsorbents.The 5%KBC-CO_(2) sample exhibited CO_(2) adsorption capacities of 3.19 and 5.01 mmol/g under respective conditions,attaining current average performance levels.Notably,CO_(2)/N_(2) selectivity(85∶15,volume ratio)reached 64.71 at 0.02 bar with robust cycling stability.Molecular dynamics simulations revealed that oxygen-containing functional groups accelerate CO_(2) adsorption kinetics and enhance micropore storage capacity.This technical route offers simplicity,environmental compatibility,and scalability,providing critical references for large-scale preparation of high-quality carbon materials.展开更多
Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were...Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were widely used for theπ-activation of unsaturated carbon−carbon bonds,particularly alkynes.Moreover,they exhibit favorable functional-group compatibility,good biocompatibility,and,generally,gold-catalyzed reactions are not sensitive to air or water.展开更多
The activation of carbon-hydrogen(C-H)bonds is of great scientific importance and offers broad applications in modern organic chemistry[1].In recent years,strategies for C-H bond activation have made notable advances,...The activation of carbon-hydrogen(C-H)bonds is of great scientific importance and offers broad applications in modern organic chemistry[1].In recent years,strategies for C-H bond activation have made notable advances,particularly in the efficient construction of complex molecular architectures.However,most existing C-H activation systems rely on expensive noble metal catalysts,including palladium,rhodium,ruthenium,and iridium.These metals not only come at a high cost but are also often associated with significant toxicity,which further limits their viability and sustainability in industrial applications.展开更多
Ynones are important skeletons in bioactive molecules and valuable building blocks for organic synthesis,thus great efforts have been devoted to their preparation.While,introducing prochiral substrates to construct yn...Ynones are important skeletons in bioactive molecules and valuable building blocks for organic synthesis,thus great efforts have been devoted to their preparation.While,introducing prochiral substrates to construct ynones bearing a chiral framework is unrealized to date.Herein,we reported the first example of Pd/SOP-catalyzed asymmetric carbonylative alkynylation via a non-classical carbonylative Sonogashiratype approach(acyl-Pd(Ⅱ)species generated from nucleophiles).By using cyclic diaryliodonium salts as prochiral substrates,various axial chiral ynones with good functional group tolerance(39 examples),satisfied yields(71%-96%)and excellent enantioselectivities(generally 94%-99%ee)were produced.Synthesis of bioactive compounds,scale-up experiment and useful transformations were also conducted to demonstrate the utility of this process.展开更多
The dectrochemical reduction characteristics of carbon tetrachlofide （CT） were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders＇...The dectrochemical reduction characteristics of carbon tetrachlofide （CT） were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders＇ iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders＇ iron. The entire CT in 350 ml aqueous solution with 320 mg/L was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with Fe/Cu ratio of 10：1 （w/w） were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were different. The degradation rate was not significantly influenced by pH in the catalyzed Fe-Cu process; in Master Builders＇ iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders＇ iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode （Cu） and anode （Fe） compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.展开更多
The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studie...The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.展开更多
Ammonium perchlorate(APC)is the most common oxidizer in use for solid rocket propulsion systems.However its initial thermal decomposition is an endothermic process that requires 102.5 J·g^-1.This manner involves ...Ammonium perchlorate(APC)is the most common oxidizer in use for solid rocket propulsion systems.However its initial thermal decomposition is an endothermic process that requires 102.5 J·g^-1.This manner involves high activation energy and could render high burning rate regime.This study reports on the sustainable fabrication of CuO nanoparticles as a novel catalyzing agent for APC oxidizer.Colloidal CuO nanoparticles with consistent product quality were fabricated by using hydrothermal processing.TEM micrographs demonstrated mono-dispersed particles of 15 nm particle size.XRD diffractogram demonstrated highly crystalline material.The synthesized colloidal CuO particles were effectively coated with APC particles via co-precipitation by using fast-crash solvent-antisolvent technique.The impact of copper oxide particles on APC thermal behavior has been investigated using DSC and TGA techniques.APC demonstrated an initial endothermic decomposition stage at 242℃ with subsequent two exothermic decomposition stages at 297,8℃ and 452.8℃ respectively.At 1 wt%,copper oxide offered decrease in initial endothermic decomposition stage by 30%.The main outcome of this study is that the two main exothermic decomposition peaks were merged into one single peak with an increase in total heat release by 53%.These novel features can inherit copper oxide particles unique catalyzing ability for advanced highly energetic systems.展开更多
The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the ...The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the sintering of ZnS and FeS and used for the pressure acid leaching experiment.The variations in the potential of the pressure leaching system were investigated by using a self-designed potential autoclave.The results showed that compared to the non-iron sphalerite,there was a violent redox reaction between the 25.70%Fe-artificial sphalerite and dissolved oxygen during the process of pressure leaching;and the catalytic mechanism was attributed to the redox couple Fe^3+/Fe^2+,where Fe3+oxidizes the H2S gas film and the reduced Fe2+state is subsequently oxidized by the dissolved oxygen.Furthermore,the effect of temperature,H2SO4 concentration,and oxygen partial pressure on the artificial sphalerite with different iron contents was studied.The sphalerite samples with iron content were observed to dissolve more easily in sulfuric acid compared to the non-iron samples.Moreover,the activation energy of artificial sphalerite was observed to be lower in the sample with 25.70%iron content(22.26 kJ/mol)compared to that with no iron(32.31 kJ/mol);and the apparent reaction orders were obtained with respect to H2SO4 concentration(1.10 and 1.36)and oxygen partial pressure(1.29 and 1.41),respectively.A comprehensive kinetic model was developed on the basis of the experimental data and the fitted leaching ratio plot;and the kinetic equations for the leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation were determined.展开更多
The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap(CCRT)system composed of a diesel oxidation catalyst(DOC)and a catalyzed diesel particulate filter(CDPF)on t...The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap(CCRT)system composed of a diesel oxidation catalyst(DOC)and a catalyzed diesel particulate filter(CDPF)on the main gaseous and particulate emissions from an urban diesel bus,as well as the durability performance of the CCRT system.Experiments were conducted based on a heavy chassis dynamometer,and a laboratory activity test as well as X-ray photoelectron spectroscopy(XPS)test were applied to evaluate the changes of the aged CCRT catalyst.Results showed that the CCRT could reduce the CO by 71.5%and the total hydrocarbons(THC)by 88.9%,and meanwhile promote the oxidation of NO.However,the conversion rates for CO and THC dropped to 25.1%and 55.1%,respectively,after the CCRT was used for one year(~60,000 km),and the NO oxidation was also weakened.For particulate emissions,the CCRT could reduce 97.4%of the particle mass(PM)and almost 100%of the particle number(PN).The aging of the CCRT resulted in a reduced PM trapping efficiency but had no observable effect on the PN;however,it increased the proportion of nucleation mode particles.The activity test results indicated that the deterioration of the CCRT was directly relevant to the increase in the light-off temperatures of the catalyst for CO,C3H8 and NO2.In addition,the decreased concentrations of the active components Pt2+ and Pt4+ in the catalyst are also important factors in the CCRT deterioration.展开更多
In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions...In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption.The reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.展开更多
The selective oxidation of 5-hydroxymethylfurfural(HMF),a versatile bio-based platform molecule,leads to the formation of several intriguing and useful downstream chemicals,such as 2,5-diformylfuran(DFF),5-hydroxymeth...The selective oxidation of 5-hydroxymethylfurfural(HMF),a versatile bio-based platform molecule,leads to the formation of several intriguing and useful downstream chemicals,such as 2,5-diformylfuran(DFF),5-hydroxymethyl-2-furancarboxylic acid(HMFCA),formyl 2-furancarboxylic acid(FFCA),2,5-furandicarboxylic acid(FDCA) and furan-2,5-dimethylcarboxylate(FDMC).These products have been extensively employed to fabricate novel polymers,pharmaceuticals,sustainable dyes and many other value-added fine chemicals.The heart of the developed HMF oxidation processes is always the catalyst.In this regard,this review comprehensively summarized the established heterogeneous catalyst design strategy for the selective oxidation of HMF via thermo-catalysis.Particular attention has been focused on the reaction mechanism of HMF oxidation over different catalysts as well as enhancing the catalytic performance of the catalyst through manipulating the properties of the support and fabricating of multi-component metal nano-particles and oxides.The current challenges and possible research directions for the catalytic oxidation of HMF in the future are also discussed.展开更多
A novel palladium-catalyzed coupling reaction for the preparation of derivatives of stilbazoles was presented. A series of stilbazoles were synthesized firstly by this highly efficient method. From this reaction it wa...A novel palladium-catalyzed coupling reaction for the preparation of derivatives of stilbazoles was presented. A series of stilbazoles were synthesized firstly by this highly efficient method. From this reaction it was found that reaction solvent is one of important factors in this catalytic system.展开更多
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
Visible light-induced organic reactions have gained much attention in recent years due to their mild conditions and high efficiency[1,2].In this context,many efficient photocatalysts including transition metal complex...Visible light-induced organic reactions have gained much attention in recent years due to their mild conditions and high efficiency[1,2].In this context,many efficient photocatalysts including transition metal complexes and organic dyes have been developed for various organic transformations.展开更多
A direct C–H amination reaction of N-Ts-2-Styrylaniline derivatives to realize the synthesis of indole derivatives was developed in the presence of copper salt. A variety of N-Ts-2-Styrylaniline derivatives were tran...A direct C–H amination reaction of N-Ts-2-Styrylaniline derivatives to realize the synthesis of indole derivatives was developed in the presence of copper salt. A variety of N-Ts-2-Styrylaniline derivatives were transformed into the corresponding indole products in good to excellent yield under mild conditions with the oxidation of potassium persulfate.展开更多
Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and al...Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and alcohols with the conversion of 15.00％～34.58％ containing of 97.60％～99.80％ ketones and alcohols. The turnover numbers of these catalysts are over 3500 mol-cat. ^(-1)for 3.5 h.展开更多
Unfixed reactive dyes stained on cotton fabric could be removed using Fe-tetra-amido macro-cyclic ligands( TAML) / H_2O_2 catalyzed oxidation system( COS). The colored washing-off wastewater also could be decolorized ...Unfixed reactive dyes stained on cotton fabric could be removed using Fe-tetra-amido macro-cyclic ligands( TAML) / H_2O_2 catalyzed oxidation system( COS). The colored washing-off wastewater also could be decolorized simultaneously in the same system. The decolourization kinetics showed that the decolourization ratio of reactive dyes in water could reach at least 80% at room temperature in 10 min,which followed the law of pseudo-first order reaction kinetics. The effects of the COS washing-off process parameters on the decolourization ratio,chemical oxygen demand( COD) of wastewater,K/S value,color fastness,color difference,and bursting strength were investigated in detail. The results showed that color fastness properties and final shade of fabric treated by COS were very similar to conventional soaping. The reactive dye molecules in wash-off bath were destroyed using the COS,potentially reduced COD which generated during conventional washing-off procedure.展开更多
Novel fluorescent coumarin-4H-pyran conjugates were achieved by three-component reactions of various synthetic β-ketoesters with aldehydes and malononitrile in aqueous media.Besides mild reaction conditions,operation...Novel fluorescent coumarin-4H-pyran conjugates were achieved by three-component reactions of various synthetic β-ketoesters with aldehydes and malononitrile in aqueous media.Besides mild reaction conditions,operational simplicity,absence of tedious separation procedures,using of inexpensive and nontoxic commercially available cationic surfactant cetyltrimethylammonium chloride（CTAC） as a catalyst are the prominent advantage of this method.展开更多
文摘The triple bond in N_(2)has an extremely high bond energy and is thus difficult to break.N_(2)is commonly converted into NH3 artificially via the Haber-Bosch process,and NH_(3)can be utilized to produce other nitrogen-containing chemicals.Here,we developed an electron catalyzed method to directly fix N_(2)into azos,by pushing and pulling the electron into and from the aromatic halide with the cyclic voltammetry method.The round-trip journey of electron can successfully weaken the triple bond in N_(2)through the electron pushing-induced aryl radical via a“brick trowel”transition state,and then produce the diazonium ions by pulling the electron out from the diazo radical intermediate.Different azos can be synthesized with this developed electron catalyzed approach.This approach provides a novel concept and practical route for the fixation of N_(2)at atmospheric pressure into chemical products valuable for industrial and commercial applications.
基金supported by the National Natural Science Foundation of China(52376103,542B2081).
文摘The technology for green and macro-conversion of solid waste biomass to prepare high-quality activated carbon demands urgent development.This study proposes a technique for synthesizing carbon adsorbents using trace KOH-catalyzed CO_(2) activation.Comprehensive investigations were conducted on three aspects:physicochemical structure evolution of biochar,mechanistic understanding of trace KOH-facilitated CO_(2) activation processes,and application characteristics for CO_(2) adsorption.Results demonstrate that biochar activated by trace KOH(<10%)and CO_(2) achieves comparable specific surface area(1244.09 m^(2)/g)to that obtained with 100%KOH activation(1425.10 m^(2)/g).The pore structure characteristics(specific surface area and pore volume)are governed by CO and CH4 generated through K-salt catalyzed reactions between CO_(2) and biochar.The optimal CO_(2) adsorption capacities of KBC adsorbent reached 4.70 mmol/g(0℃)and 7.25 mmol/g(25℃),representing the maximum values among comparable carbon adsorbents.The 5%KBC-CO_(2) sample exhibited CO_(2) adsorption capacities of 3.19 and 5.01 mmol/g under respective conditions,attaining current average performance levels.Notably,CO_(2)/N_(2) selectivity(85∶15,volume ratio)reached 64.71 at 0.02 bar with robust cycling stability.Molecular dynamics simulations revealed that oxygen-containing functional groups accelerate CO_(2) adsorption kinetics and enhance micropore storage capacity.This technical route offers simplicity,environmental compatibility,and scalability,providing critical references for large-scale preparation of high-quality carbon materials.
文摘Gold,unlike other transition metals such as Pd,Ni,and Cu,offers unique reactivity profiles and has emerged as an attractive area of research in organic chemistry over the last two decades.Initially,gold catalysts were widely used for theπ-activation of unsaturated carbon−carbon bonds,particularly alkynes.Moreover,they exhibit favorable functional-group compatibility,good biocompatibility,and,generally,gold-catalyzed reactions are not sensitive to air or water.
文摘The activation of carbon-hydrogen(C-H)bonds is of great scientific importance and offers broad applications in modern organic chemistry[1].In recent years,strategies for C-H bond activation have made notable advances,particularly in the efficient construction of complex molecular architectures.However,most existing C-H activation systems rely on expensive noble metal catalysts,including palladium,rhodium,ruthenium,and iridium.These metals not only come at a high cost but are also often associated with significant toxicity,which further limits their viability and sustainability in industrial applications.
基金supported financially by National Nature Science Foundation of China(No.22171258)the Youth Innovation Promotion Association CAS(No.2022375)+1 种基金the Biological Resources Programme,Chinese Academy of Sciences(No.KFJ-BRP-008)the Sichuan Science and Technology Program(No.2022ZYD0038)。
文摘Ynones are important skeletons in bioactive molecules and valuable building blocks for organic synthesis,thus great efforts have been devoted to their preparation.While,introducing prochiral substrates to construct ynones bearing a chiral framework is unrealized to date.Herein,we reported the first example of Pd/SOP-catalyzed asymmetric carbonylative alkynylation via a non-classical carbonylative Sonogashiratype approach(acyl-Pd(Ⅱ)species generated from nucleophiles).By using cyclic diaryliodonium salts as prochiral substrates,various axial chiral ynones with good functional group tolerance(39 examples),satisfied yields(71%-96%)and excellent enantioselectivities(generally 94%-99%ee)were produced.Synthesis of bioactive compounds,scale-up experiment and useful transformations were also conducted to demonstrate the utility of this process.
基金Project supported by the Hi-Tech Research and Development Program(863) of China (No. 2002AA601270)
文摘The dectrochemical reduction characteristics of carbon tetrachlofide （CT） were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders＇ iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders＇ iron. The entire CT in 350 ml aqueous solution with 320 mg/L was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with Fe/Cu ratio of 10：1 （w/w） were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were different. The degradation rate was not significantly influenced by pH in the catalyzed Fe-Cu process; in Master Builders＇ iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders＇ iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode （Cu） and anode （Fe） compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.
文摘The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.
文摘Ammonium perchlorate(APC)is the most common oxidizer in use for solid rocket propulsion systems.However its initial thermal decomposition is an endothermic process that requires 102.5 J·g^-1.This manner involves high activation energy and could render high burning rate regime.This study reports on the sustainable fabrication of CuO nanoparticles as a novel catalyzing agent for APC oxidizer.Colloidal CuO nanoparticles with consistent product quality were fabricated by using hydrothermal processing.TEM micrographs demonstrated mono-dispersed particles of 15 nm particle size.XRD diffractogram demonstrated highly crystalline material.The synthesized colloidal CuO particles were effectively coated with APC particles via co-precipitation by using fast-crash solvent-antisolvent technique.The impact of copper oxide particles on APC thermal behavior has been investigated using DSC and TGA techniques.APC demonstrated an initial endothermic decomposition stage at 242℃ with subsequent two exothermic decomposition stages at 297,8℃ and 452.8℃ respectively.At 1 wt%,copper oxide offered decrease in initial endothermic decomposition stage by 30%.The main outcome of this study is that the two main exothermic decomposition peaks were merged into one single peak with an increase in total heat release by 53%.These novel features can inherit copper oxide particles unique catalyzing ability for advanced highly energetic systems.
基金Projects(51804136,51764016)supported by the National Natural Science Foundation of ChinaProject(U1402271)supported by the Joint Funds of the National Natural Science Foundation of China+2 种基金Project(20181BAB216017)supported by the Jiangxi Provincial Natural Science Foundation,ChinaProject(GK-201803)supported by the Research Fund Program of State Key Laboratory of Rare Metals Separation and Comprehensive Utilization,ChinaProjects(yy2016001,yy2016012)supported by the Research Fund Program of the State Key Laboratory of Pressure Hydrometallurgical Technology of Associated Nonferrous Metal Resources,China。
文摘The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the sintering of ZnS and FeS and used for the pressure acid leaching experiment.The variations in the potential of the pressure leaching system were investigated by using a self-designed potential autoclave.The results showed that compared to the non-iron sphalerite,there was a violent redox reaction between the 25.70%Fe-artificial sphalerite and dissolved oxygen during the process of pressure leaching;and the catalytic mechanism was attributed to the redox couple Fe^3+/Fe^2+,where Fe3+oxidizes the H2S gas film and the reduced Fe2+state is subsequently oxidized by the dissolved oxygen.Furthermore,the effect of temperature,H2SO4 concentration,and oxygen partial pressure on the artificial sphalerite with different iron contents was studied.The sphalerite samples with iron content were observed to dissolve more easily in sulfuric acid compared to the non-iron samples.Moreover,the activation energy of artificial sphalerite was observed to be lower in the sample with 25.70%iron content(22.26 kJ/mol)compared to that with no iron(32.31 kJ/mol);and the apparent reaction orders were obtained with respect to H2SO4 concentration(1.10 and 1.36)and oxygen partial pressure(1.29 and 1.41),respectively.A comprehensive kinetic model was developed on the basis of the experimental data and the fitted leaching ratio plot;and the kinetic equations for the leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation were determined.
基金supported by the National Key Research and Development Program of China (No. YS2017ZY020019)Research Project of Shanghai Committee of Science and Technology (No. 18DZ1202900)the China Scholarship Council (No. 201806260133)
文摘The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap(CCRT)system composed of a diesel oxidation catalyst(DOC)and a catalyzed diesel particulate filter(CDPF)on the main gaseous and particulate emissions from an urban diesel bus,as well as the durability performance of the CCRT system.Experiments were conducted based on a heavy chassis dynamometer,and a laboratory activity test as well as X-ray photoelectron spectroscopy(XPS)test were applied to evaluate the changes of the aged CCRT catalyst.Results showed that the CCRT could reduce the CO by 71.5%and the total hydrocarbons(THC)by 88.9%,and meanwhile promote the oxidation of NO.However,the conversion rates for CO and THC dropped to 25.1%and 55.1%,respectively,after the CCRT was used for one year(~60,000 km),and the NO oxidation was also weakened.For particulate emissions,the CCRT could reduce 97.4%of the particle mass(PM)and almost 100%of the particle number(PN).The aging of the CCRT resulted in a reduced PM trapping efficiency but had no observable effect on the PN;however,it increased the proportion of nucleation mode particles.The activity test results indicated that the deterioration of the CCRT was directly relevant to the increase in the light-off temperatures of the catalyst for CO,C3H8 and NO2.In addition,the decreased concentrations of the active components Pt2+ and Pt4+ in the catalyst are also important factors in the CCRT deterioration.
基金sponsored by the National Engineering Laboratory for Mobile Source Emission Control Technology (No. NELMS2020A02)Shanghai Sailing Program (No. 21YF1448900)。
文摘In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption.The reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.
基金funding supported by the National Natural Science Foundation of China (Grant Nos. 2207827521978246)+3 种基金the National Key Research and Development Program of China (Grant No. 2019YFB1503903)the Key Area Research and Development Program of Guangdong Province (Grant No. 2020B0101070001)the Fundamental Research Funds for the Central Universities (Grant No. 20720190014)PetroChina Innovation Foundation (2019D5007-0413)。
文摘The selective oxidation of 5-hydroxymethylfurfural(HMF),a versatile bio-based platform molecule,leads to the formation of several intriguing and useful downstream chemicals,such as 2,5-diformylfuran(DFF),5-hydroxymethyl-2-furancarboxylic acid(HMFCA),formyl 2-furancarboxylic acid(FFCA),2,5-furandicarboxylic acid(FDCA) and furan-2,5-dimethylcarboxylate(FDMC).These products have been extensively employed to fabricate novel polymers,pharmaceuticals,sustainable dyes and many other value-added fine chemicals.The heart of the developed HMF oxidation processes is always the catalyst.In this regard,this review comprehensively summarized the established heterogeneous catalyst design strategy for the selective oxidation of HMF via thermo-catalysis.Particular attention has been focused on the reaction mechanism of HMF oxidation over different catalysts as well as enhancing the catalytic performance of the catalyst through manipulating the properties of the support and fabricating of multi-component metal nano-particles and oxides.The current challenges and possible research directions for the catalytic oxidation of HMF in the future are also discussed.
基金This work was supported by Foundation from President of the Chinese Academic of Science and NSFC.
文摘A novel palladium-catalyzed coupling reaction for the preparation of derivatives of stilbazoles was presented. A series of stilbazoles were synthesized firstly by this highly efficient method. From this reaction it was found that reaction solvent is one of important factors in this catalytic system.
基金Supported by the Foundation of Education Committee of Liaoning Province (No. 990321076)
文摘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.
文摘Visible light-induced organic reactions have gained much attention in recent years due to their mild conditions and high efficiency[1,2].In this context,many efficient photocatalysts including transition metal complexes and organic dyes have been developed for various organic transformations.
基金financially supported by the National Natural Science Foundation of China(Nos.21272169,21302135)the Key Innovation Team of Science & Technology in Zhejiang Province(No.2010R50018-10)+1 种基金the Science and Technology Bureau of Taizhou(No.08KY10)the Key Disciplines of Applied Chemistry of Zhejiang Province,Taizhou University
文摘A direct C–H amination reaction of N-Ts-2-Styrylaniline derivatives to realize the synthesis of indole derivatives was developed in the presence of copper salt. A variety of N-Ts-2-Styrylaniline derivatives were transformed into the corresponding indole products in good to excellent yield under mild conditions with the oxidation of potassium persulfate.
文摘Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and alcohols with the conversion of 15.00％～34.58％ containing of 97.60％～99.80％ ketones and alcohols. The turnover numbers of these catalysts are over 3500 mol-cat. ^(-1)for 3.5 h.
基金National Key Technology R&D Program,China(No.2011BAE07B08)the Fundamental Research Funds for the Central Universities,China(No.2232013D3-26)
文摘Unfixed reactive dyes stained on cotton fabric could be removed using Fe-tetra-amido macro-cyclic ligands( TAML) / H_2O_2 catalyzed oxidation system( COS). The colored washing-off wastewater also could be decolorized simultaneously in the same system. The decolourization kinetics showed that the decolourization ratio of reactive dyes in water could reach at least 80% at room temperature in 10 min,which followed the law of pseudo-first order reaction kinetics. The effects of the COS washing-off process parameters on the decolourization ratio,chemical oxygen demand( COD) of wastewater,K/S value,color fastness,color difference,and bursting strength were investigated in detail. The results showed that color fastness properties and final shade of fabric treated by COS were very similar to conventional soaping. The reactive dye molecules in wash-off bath were destroyed using the COS,potentially reduced COD which generated during conventional washing-off procedure.
基金the financial support from the National Natural Science Foundation of China(No.21462041)Natural-Science Foundation for Distinguished Young Scholars of Xinjiang Uyghur Autonomous Region(No.Qn2015jq002)the Tianshan Talent Cultivation Project of Xinjiang Uyghur Autonomous Region
文摘Novel fluorescent coumarin-4H-pyran conjugates were achieved by three-component reactions of various synthetic β-ketoesters with aldehydes and malononitrile in aqueous media.Besides mild reaction conditions,operational simplicity,absence of tedious separation procedures,using of inexpensive and nontoxic commercially available cationic surfactant cetyltrimethylammonium chloride（CTAC） as a catalyst are the prominent advantage of this method.
