The optimization of reaction processes is crucial for the green, efficient, and sustainable development of the chemical industry. However, how to address the problems posed by multiple variables, nonlinearities, and u...The optimization of reaction processes is crucial for the green, efficient, and sustainable development of the chemical industry. However, how to address the problems posed by multiple variables, nonlinearities, and uncertainties during optimization remains a formidable challenge. In this study, a strategy combining interpretable machine learning with metaheuristic optimization algorithms is employed to optimize the reaction process. First, experimental data from a biodiesel production process are collected to establish a database. These data are then used to construct a predictive model based on artificial neural network (ANN) models. Subsequently, interpretable machine learning techniques are applied for quantitative analysis and verification of the model. Finally, four metaheuristic optimization algorithms are coupled with the ANN model to achieve the desired optimization. The research results show that the methanol: palm fatty acid distillate (PFAD) molar ratio contributes the most to the reaction outcome, accounting for 41%. The ANN-simulated annealing (SA) hybrid method is more suitable for this optimization, and the optimal process parameters are a catalyst concentration of 3.00% (mass), a methanol: PFAD molar ratio of 8.67, and a reaction time of 30 min. This study provides deeper insights into reaction process optimization, which will facilitate future applications in various reaction optimization processes.展开更多
The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions f...The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions for preparing well-dispersed nanoparticles were found as follows: 0.4 mol/L NaBH4 was added into solution containing 0.2 mol/L Cu2+, 1.0% gelatin dispersant in mass fraction, and 1.2 mol/L NH3?H2O at pH 12 and 313 K. In addition, a series of experiments were performed to discover the reaction process. NH3?H2O was found to be able to modulate the reaction process. At pH=10, Cu2+ was transformed to Cu(NH3)42+ as precursor after the addition of NH3?H2O, and then Cu(NH3)42+ was reduced by NaBH4 solution. At pH=12, Cu2+ was transformed to Cu(OH)2 as precursor after the addition of NH3?H2O, and Cu(OH)2 was then reduced by NaBH4 solution.展开更多
Solar-driven photocatalytic hydrogen production via water splitting is considered as one of the most promising green and sustainable strategies,with the potential to replace traditional fossil fuels[1,2].Generally,thi...Solar-driven photocatalytic hydrogen production via water splitting is considered as one of the most promising green and sustainable strategies,with the potential to replace traditional fossil fuels[1,2].Generally,this photocatalytic reaction process includes the following steps:First,the semiconductor photocatalyst is photoexcited to generate photoinduced excitons on a femtosecond timescale.Next,the photoinduced excitons are separated into photogenerated electrons and holes,occurring within a femtosecond to picosecond timescale.Subsequently,only a small fraction of the photogenerated electrons and holes can overcome kinetic barriers,such as phonon scattering and bulk defects,to migrate to the surface。展开更多
M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr （ Ⅳ ） of Na2 CrO4 borne in the chromium slag to Cr （ Ⅲ ） in the solid phase re...M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr （ Ⅳ ） of Na2 CrO4 borne in the chromium slag to Cr （ Ⅲ ） in the solid phase reaction, and its thermodynamics and kinetics were studied. The reduction process of Na2CrO4 by carbon produced CO, whiCh＇was endothermic. Under the experimental condition, the apparent activation energy was 4. 41 kJ·mol^-1 , the＇apparent order of reaction for Na2 CrO4 was equal to one, and the partial pressure of CO was only 0.22 Pa at 1 330℃.展开更多
The reaction kinetics of roasting zinc silicate using NaOH was investigated.The orthogonal test was employed to optimize the reaction conditions and the optimized reaction conditions were as follows:molar ratio of NaO...The reaction kinetics of roasting zinc silicate using NaOH was investigated.The orthogonal test was employed to optimize the reaction conditions and the optimized reaction conditions were as follows:molar ratio of NaOH to Zn2SiO4 of 16:1,reaction temperature of 550°C,and reaction time of 2.5 h.In order to ascertain the phases transformation and reaction processes of zinc oxide and silica,the XRD phase analysis was used to analyze the phases of these specimens roasted at different temperatures.The final phases of the specimen roasted at 600°C were Na2ZnO2,Na4SiO4,Na2ZnSiO4 and NaOH.The reaction kinetic equation of roasting was determined by the shrinking unreacted core model.Aiming to investigate the reaction mechanism,two control models of reaction rate were applied:chemical reaction at the particle surface and diffusion through the product layer.The results indicated that the diffusion through the product layer model described the reaction process well.The apparent activation energy of the roasting was 19.77 kJ/mol.展开更多
Amine-based carbon dioxide(CO2)capture is still limited by high desorption energy consumption.Fixing CO2 into carbonate is a safer and more permanent method.In this work,calcium oxide(CaO)is introduced to perform chem...Amine-based carbon dioxide(CO2)capture is still limited by high desorption energy consumption.Fixing CO2 into carbonate is a safer and more permanent method.In this work,calcium oxide(CaO)is introduced to perform chemical desorption instead of thermal desorption on 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)aqueous solution after CO2 absorption.The X-ray diffraction(XRD)patterns of solid products show the formation of calcite calcium carbonate(CaCO3),which prove the feasibility of this method.The effects of reaction temperature,reaction time and Ca2+/CO32-molar ratios on the related reactions in CO2 absorption-mineralization process and CaCO3 precipitation are discussed,and purer CaCO3 is obtained by ultrasonic treatment.The CaCO3 content can be increased to 95.8%and the CO2 desorption ratio can achieve 80%by 30 min ultrasonic dispersion treatment under the conditions(40℃,180 min,Ca2+/CO32-molar ratio=1.0).After five cycles,DBU aqueous solution shows stable CO2 absorption and mineralization ability.Fourier transform infrared spectroscopy(FT-IR)spectra of the reaction process also indicate the regeneration of the solvent.Compared with thermal desorption,this process is exothermic,almost without no additional heat.展开更多
β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the ...β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope,and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1773 K.展开更多
A new material with heat-resistant and adiabatic characteristics and high strength was prepared using the combustion synthesis method by mixed powders of CrO3, Al, Al2O3, and NaF in atmospheric gas. The reaction dynam...A new material with heat-resistant and adiabatic characteristics and high strength was prepared using the combustion synthesis method by mixed powders of CrO3, Al, Al2O3, and NaF in atmospheric gas. The reaction dynamic process of the Al-CrO3-NaF-Al2O3-N2-O2 new material system by the combustion synthesis method was discussed based on the observation results by SEM, EDS, and XRD in combination with the combustion front quenching method （CFQM） and the relation curves between reaction free enthalpies and the corresponding temperatures. The combustion synthesis mechanism and the formation reasons of the phase in the combustion product were analyzed.展开更多
In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuou...In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling （DMM） instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy （EDX） and X-ray diffraction （XRD） of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-α-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TLA1 as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.展开更多
The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic re...The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic reaction is constrained by thermodynamic equilibrium and involves a complex reaction network, leading to a heightened focus on catalysts and process design. Copper-based catalysts have been extensively studied and exhibit exceptional low-temperature catalytic performance in cyclohexanol dehydrogenation, with some being commercially used in the industry. This paper specifically concentrates on research advancement concerning active species, reaction mechanisms, factors influencing product selectivity, and the deactivation behaviors of copper-based catalysts. Moreover, a brief introduction to the new processes that break thermodynamic equilibrium via reaction coupling and their corresponding catalysts is summarized here as well. These reviews may off er guidance and potential avenues for further investigations into catalysts and processes for cyclohexanol dehydrogenation.展开更多
Based on the theory of relativistic superstrong magnetic fields （SMFs）, by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening （SES） in SMFs and the influ...Based on the theory of relativistic superstrong magnetic fields （SMFs）, by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening （SES） in SMFs and the influence of SES on the nuclear reaction of 23Mg （p, Y）24A1. Our calculations show that the nuclear reaction will be markedly effected by the SES in SMFs in the surface of magnetars. Our calculated screening rates can increase two orders of magnitude due to SES in SMFs.展开更多
The water-gas shift(WGS)reaction plays a pivotal role in various industrial processes,particularly in hydrogen production and carbon monoxide removal.As global energy demands rise and environmental concerns intensify,...The water-gas shift(WGS)reaction plays a pivotal role in various industrial processes,particularly in hydrogen production and carbon monoxide removal.As global energy demands rise and environmental concerns intensify,the development of efficient and sustainable catalysts for the low-temperature WGS(LT-WGS)reaction has gained significant attention.This review focuses on recent advancements in water-gas-shift catalyst design for low-temperature conditions and emerging renewable energy-driven catalytic processes,such as photocatalysis,electrocatalysis,and plasma catalysis for the WGS reaction,which are less commonly explored in existing reviews.We systematically analyze mechanisms studies of LT-WGS,rational catalyst design strategies,and recent frontier advances in the development of highly efficient catalysts.Furthermore,this review provides actionable insights for refining catalyst architectures,enhancing operational efficiency,elucidating reaction pathways,and pioneering hybrid technologies,all contributing to further advancements in this field.展开更多
In this study,the effects of reaction parameters on the deep-reduction and carbonization process of WO_(2)-Co to WC-Co were studied.The results indicate that the oxygen loss rate of WO_(2) is positively correlated wit...In this study,the effects of reaction parameters on the deep-reduction and carbonization process of WO_(2)-Co to WC-Co were studied.The results indicate that the oxygen loss rate of WO_(2) is positively correlated with temperature and methane partial pressure.The partial pressure of methane has no significant effect on the formation rate of WC.The carbon content and particle size of the product increase with the increase of CH_(4) partial pressure.By synergistically regulating the reaction temperature to 950℃,the CH_(4) partial pressure to 1.25%,and the reaction time to 60 min,ultrafine WC-Co powder without η phase can be obtained.The particle size of the composite powder is 128 nm,with total carbon content of 6.16%,free carbon content of 0.4%,and residual oxygen content of 0.05%,respectively.The growth rate relationship of tungsten carbide is as follows:δ(t)=1.21×10^(-13)exp(-12809.72/T)√t.展开更多
Annular channeling has seriously troubled deep oil and gas exploitation,and the reduction of hydrostatic pressure of cement slurry in the waiting stage is considered one of the main causes of early annular channeling....Annular channeling has seriously troubled deep oil and gas exploitation,and the reduction of hydrostatic pressure of cement slurry in the waiting stage is considered one of the main causes of early annular channeling.However,at present,there is still a lack of sufficient research on and understanding of the relationship between the time-varying law of hydrostatic pressure of cement slurry and the early hydration process in different well sections,especially in high-temperature well sections.Therefore,in this paper,a hydrostatic pressure measurement experiment of cement slurry at low temperature(50-90℃)and high temperature(120-180℃)was carried out using a self-developed hydrostatic pressure measurement device of cement slurry.Then,the cement slurry cured at 90℃ for 1-8 h was sampled by the freeze-drying method,and XRD and TG experiments were carried out.The results show that the hydrostatic curves of low and high temperatures both show a trend of rapid increase first,then remain stable,and then decrease rapidly.With an increase in temperature,the time of the stable and falling segments of the hydrostatic curve of the cement slurry gradually decreases.By fitting the rapid pressure drop time points of cement slurry at different temperatures,it can be determined that the rapid pressure drop time and temperature show a functional relationship.The XRD and TG results of different curing times at 90℃ were analyzed.It can be seen that in the early stage of the hydration induction period,the connection between cement particles is not close,and the hydrostatic pressure of the cement slurry column remains stable.As the hydration process enters the acceleration period,the cement particles crosslink with each other through hydration products to form a bridge structure,and the hydrostatic pressure of the cement paste begins to decrease.This shows that the pressure drop time can be controlled by regulating the hydration process to provide theoretical guidance for cement slurry preparation and slurry column design in cementing engineering.展开更多
Carbon-fueled solid oxide fuel cells(CF-SOFCs)can electrochemically convert the chemical energy in carbon into electricity,which demonstrate both superior electrical efficiency and fuel utilisation compared to all oth...Carbon-fueled solid oxide fuel cells(CF-SOFCs)can electrochemically convert the chemical energy in carbon into electricity,which demonstrate both superior electrical efficiency and fuel utilisation compared to all other types of fuel cells.However,using solid carbon as the fuel of SOFCs also faces some challenges,the fluid mobility and reactive activity of carbon-based fuels are much lower than those of gaseous fuels.Therefore,the anode reaction kinetics plays a crucial role in determining the electrochemical performance of CF-SOFCs.Herein,the progress of various anodes in CF-SOFCs is reviewed from the perspective of material compositions,electrochemical performance and microstructures.Challenges faced in developing high performance anodes for CF-SOFCs are also discussed.展开更多
The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like ...The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like screening model. Association pathway and dissocia-tion pathway were investigated by the comparison of several energies. The cleavage energy of Pd（PR3）2 complex was calculated, as well as the oxidative addition reaction barrier energy of Pd（PR3）n （n=1,2） with aryl bromide in N,N-dimethylformamide solvent. This study proved that the ligands volume possessed a great impact on the mechanism of oxidative addition： less bulky ligand palladium associated with aryl bromide via two donor ligands,but larger bulky ligand palladium coordinated via monoligand.展开更多
Zirconia-mullite-corundum composites were successfully prepared from fly ash,zircon and alumina powder by a reaction sintering process.The phase and microstructure evolutions of the composite synthesized at desired te...Zirconia-mullite-corundum composites were successfully prepared from fly ash,zircon and alumina powder by a reaction sintering process.The phase and microstructure evolutions of the composite synthesized at desired temperatures of 1 400,1 500 and 1 600°C for 4 h were characterized by X-ray diffractometry and scanning electronic microscopy,respectively.The influences of sintering temperature on shrinkage ratio,apparent porosity and bulk density of the synthesized composite were investigated.The formation process of the composites was discussed in detail.The results show that the zirconia-mullite-corundum composites with good sintering properties can be prepared at 1 600°C for 4 h.Zirconia particles can be homogeneously distributed in mullite matrix,and the zirconia particles are around 5μm.The formation process of zirconia-mullite-corundum composites consists of decomposition of zircon and mullitization process.展开更多
Currently,photocatalytic water splitting is regarded as promising technology in renewable energy generation.However,the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers...Currently,photocatalytic water splitting is regarded as promising technology in renewable energy generation.However,the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers.Rational designed the structure and doping elements become important alternative routes to improve the performance of photocatalyst.In this work,we rational designed oxygen-doped graphitic carbon nitride(OCN)nanotubes derived from supermolecular intermediates for photocata lytic water splitting.The as prepared OCN nanotubes exhibit an outstanding hydrogen evolution rate of 73.84μmol h^(-1),outperforming the most of reported one dimensional(1D)g-C_(3)N_(4) previously.Due to the rational oxygen doping,the band structure of g-C_(3)N_(4) is meliorated,which can narrow the band gap and reduce the recombination rate of photogene rated carriers.Furthermore,the hollow nanotube structure of OCN also provide multiple diffuse reflection during photocata lytic reaction,which can significantly promote the utilization capacity of visible light and enhance the photocatalytic water splitting performance.It is believed that our work not only rationally controls the nanostructure,but also introduces useful heteroatom into the matrix of photocatalyst,which provides an effective way to design high-efficiency g-C_(3)N_(4) photocatalyst.展开更多
In situ Al2O3 whiskers reinforced Ti-Al intermetallic composites were fabricated at ~1200℃ by reaction sintering of cold-consolidated fillets consisting mainly of Ti, Al, and different additives. The phases and micro...In situ Al2O3 whiskers reinforced Ti-Al intermetallic composites were fabricated at ~1200℃ by reaction sintering of cold-consolidated fillets consisting mainly of Ti, Al, and different additives. The phases and microstructures of the sintered composites were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The process of synthesis was investigated using differential thermal analysis (DTA). The effects of processing parameters and additives on the microstructures of the composites and the development of whisker were examined. It is found that the morphology of the whisker is strongly influenced by the additives, the exothermal reaction process, and the processing parameters.展开更多
Non-thermal plasma technology is a new type of odor treatment processing.We deal with H2Sfrom waste gas emission using non-thermal plasma generated by dielectric barrier discharge.On the basis of two criteria,removal ...Non-thermal plasma technology is a new type of odor treatment processing.We deal with H2Sfrom waste gas emission using non-thermal plasma generated by dielectric barrier discharge.On the basis of two criteria,removal efficiency and absolute removal amount,we deeply investigate the changes in electrical parameters and process parameters,and the reaction process of the influence of ozone on H2S gas removal.The experimental results show that H2S removal efficiency is proportional to the voltage,frequency,power,residence time and energy efficiency,while it is inversely proportional to the initial concentration of H2S gas,and ozone concentration.This study lays the foundations of non-thermal plasma technology for further commercial application.展开更多
基金supported by the National Natural Science Foundation of China(22408227,22238005)the Postdoctoral Research Foundation of China(GZC20231576).
文摘The optimization of reaction processes is crucial for the green, efficient, and sustainable development of the chemical industry. However, how to address the problems posed by multiple variables, nonlinearities, and uncertainties during optimization remains a formidable challenge. In this study, a strategy combining interpretable machine learning with metaheuristic optimization algorithms is employed to optimize the reaction process. First, experimental data from a biodiesel production process are collected to establish a database. These data are then used to construct a predictive model based on artificial neural network (ANN) models. Subsequently, interpretable machine learning techniques are applied for quantitative analysis and verification of the model. Finally, four metaheuristic optimization algorithms are coupled with the ANN model to achieve the desired optimization. The research results show that the methanol: palm fatty acid distillate (PFAD) molar ratio contributes the most to the reaction outcome, accounting for 41%. The ANN-simulated annealing (SA) hybrid method is more suitable for this optimization, and the optimal process parameters are a catalyst concentration of 3.00% (mass), a methanol: PFAD molar ratio of 8.67, and a reaction time of 30 min. This study provides deeper insights into reaction process optimization, which will facilitate future applications in various reaction optimization processes.
文摘The preparation of Cu nanoparticles by the aqueous solution reduction method was investigated. The effects of different reaction parameters on the preparation of Cu nanoparticles were studied. The optimum conditions for preparing well-dispersed nanoparticles were found as follows: 0.4 mol/L NaBH4 was added into solution containing 0.2 mol/L Cu2+, 1.0% gelatin dispersant in mass fraction, and 1.2 mol/L NH3?H2O at pH 12 and 313 K. In addition, a series of experiments were performed to discover the reaction process. NH3?H2O was found to be able to modulate the reaction process. At pH=10, Cu2+ was transformed to Cu(NH3)42+ as precursor after the addition of NH3?H2O, and then Cu(NH3)42+ was reduced by NaBH4 solution. At pH=12, Cu2+ was transformed to Cu(OH)2 as precursor after the addition of NH3?H2O, and Cu(OH)2 was then reduced by NaBH4 solution.
文摘Solar-driven photocatalytic hydrogen production via water splitting is considered as one of the most promising green and sustainable strategies,with the potential to replace traditional fossil fuels[1,2].Generally,this photocatalytic reaction process includes the following steps:First,the semiconductor photocatalyst is photoexcited to generate photoinduced excitons on a femtosecond timescale.Next,the photoinduced excitons are separated into photogenerated electrons and holes,occurring within a femtosecond to picosecond timescale.Subsequently,only a small fraction of the photogenerated electrons and holes can overcome kinetic barriers,such as phonon scattering and bulk defects,to migrate to the surface。
基金Item Sponsored by National Natural Science Foundation of China (50234040)
文摘M, a particular industrial waste, was selected to detoxify chromium slag at a high temperature. The carbon remaining in M reduced Cr （ Ⅳ ） of Na2 CrO4 borne in the chromium slag to Cr （ Ⅲ ） in the solid phase reaction, and its thermodynamics and kinetics were studied. The reduction process of Na2CrO4 by carbon produced CO, whiCh＇was endothermic. Under the experimental condition, the apparent activation energy was 4. 41 kJ·mol^-1 , the＇apparent order of reaction for Na2 CrO4 was equal to one, and the partial pressure of CO was only 0.22 Pa at 1 330℃.
基金Projects(51774070,51204054)supported by the National Natural Science Foundation of ChinaProject(150204009)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2014CB643405)supported by the National Basic Research Program of China
文摘The reaction kinetics of roasting zinc silicate using NaOH was investigated.The orthogonal test was employed to optimize the reaction conditions and the optimized reaction conditions were as follows:molar ratio of NaOH to Zn2SiO4 of 16:1,reaction temperature of 550°C,and reaction time of 2.5 h.In order to ascertain the phases transformation and reaction processes of zinc oxide and silica,the XRD phase analysis was used to analyze the phases of these specimens roasted at different temperatures.The final phases of the specimen roasted at 600°C were Na2ZnO2,Na4SiO4,Na2ZnSiO4 and NaOH.The reaction kinetic equation of roasting was determined by the shrinking unreacted core model.Aiming to investigate the reaction mechanism,two control models of reaction rate were applied:chemical reaction at the particle surface and diffusion through the product layer.The results indicated that the diffusion through the product layer model described the reaction process well.The apparent activation energy of the roasting was 19.77 kJ/mol.
基金the National Natural Science Foundation of China(No.21878190)National Key R&D Program of China(2018YFB0605700)for financial support。
文摘Amine-based carbon dioxide(CO2)capture is still limited by high desorption energy consumption.Fixing CO2 into carbonate is a safer and more permanent method.In this work,calcium oxide(CaO)is introduced to perform chemical desorption instead of thermal desorption on 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)aqueous solution after CO2 absorption.The X-ray diffraction(XRD)patterns of solid products show the formation of calcite calcium carbonate(CaCO3),which prove the feasibility of this method.The effects of reaction temperature,reaction time and Ca2+/CO32-molar ratios on the related reactions in CO2 absorption-mineralization process and CaCO3 precipitation are discussed,and purer CaCO3 is obtained by ultrasonic treatment.The CaCO3 content can be increased to 95.8%and the CO2 desorption ratio can achieve 80%by 30 min ultrasonic dispersion treatment under the conditions(40℃,180 min,Ca2+/CO32-molar ratio=1.0).After five cycles,DBU aqueous solution shows stable CO2 absorption and mineralization ability.Fourier transform infrared spectroscopy(FT-IR)spectra of the reaction process also indicate the regeneration of the solvent.Compared with thermal desorption,this process is exothermic,almost without no additional heat.
基金Project(50274021) supported by the National Natural Science Foundation of China and Baoshan Iron and Steel Co., Ltd.
文摘β-Sialon/ZrN bonded corundum composites were synthesized using fused white corundum,alumina micro powder,zircon and carbon black by nitridation reaction sintering process. Phase composition and microstructure of the synthesized composites were investigated by X-ray powder diffraction and scanning electronic microscope,and the formation process of the composites was discussed. The results show that the composites with different compositions can be obtained by controlling the heating temperature and contents of zircon and carbon black. The proper temperature to synthesize the composites is 1773 K.
基金the National High-Tech Research and Development Program of China (863 Program) (No. 2006AA03Z351).
文摘A new material with heat-resistant and adiabatic characteristics and high strength was prepared using the combustion synthesis method by mixed powders of CrO3, Al, Al2O3, and NaF in atmospheric gas. The reaction dynamic process of the Al-CrO3-NaF-Al2O3-N2-O2 new material system by the combustion synthesis method was discussed based on the observation results by SEM, EDS, and XRD in combination with the combustion front quenching method （CFQM） and the relation curves between reaction free enthalpies and the corresponding temperatures. The combustion synthesis mechanism and the formation reasons of the phase in the combustion product were analyzed.
文摘In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling （DMM） instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy （EDX） and X-ray diffraction （XRD） of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-α-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TLA1 as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.
基金the support from Clariant International Ltd.the National Natural Science Foundation of China (Nos.22022811,21938008,and U21B2096)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘The dehydrogenation of cyclohexanol to cyclohexanone is a crucial industrial process in the production of caprolactam and adipic acid, both of which serve as important precursors in nylon textiles. This endothermic reaction is constrained by thermodynamic equilibrium and involves a complex reaction network, leading to a heightened focus on catalysts and process design. Copper-based catalysts have been extensively studied and exhibit exceptional low-temperature catalytic performance in cyclohexanol dehydrogenation, with some being commercially used in the industry. This paper specifically concentrates on research advancement concerning active species, reaction mechanisms, factors influencing product selectivity, and the deactivation behaviors of copper-based catalysts. Moreover, a brief introduction to the new processes that break thermodynamic equilibrium via reaction coupling and their corresponding catalysts is summarized here as well. These reviews may off er guidance and potential avenues for further investigations into catalysts and processes for cyclohexanol dehydrogenation.
基金supported in part by the National Natural Science Foundation of China through grant No. 11565020the Natural Science Foundation of Hainan province under grant No. 114012the Undergraduate Innovation Program of Hainan province under grant No. 20130139
文摘Based on the theory of relativistic superstrong magnetic fields （SMFs）, by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening （SES） in SMFs and the influence of SES on the nuclear reaction of 23Mg （p, Y）24A1. Our calculations show that the nuclear reaction will be markedly effected by the SES in SMFs in the surface of magnetars. Our calculated screening rates can increase two orders of magnitude due to SES in SMFs.
基金supported by the National Key R&D Program of China(Grant No.2024YFB4006702)Dalian Science and Technology Talent Innovation Support Program Project(Grant No.2023RY011)+1 种基金Dalian Science and Technology Innovation Fund Project(Grant No.2024JJ12CG031)Dalian University of Technology Xinghai Outstanding Young Scholar Program.
文摘The water-gas shift(WGS)reaction plays a pivotal role in various industrial processes,particularly in hydrogen production and carbon monoxide removal.As global energy demands rise and environmental concerns intensify,the development of efficient and sustainable catalysts for the low-temperature WGS(LT-WGS)reaction has gained significant attention.This review focuses on recent advancements in water-gas-shift catalyst design for low-temperature conditions and emerging renewable energy-driven catalytic processes,such as photocatalysis,electrocatalysis,and plasma catalysis for the WGS reaction,which are less commonly explored in existing reviews.We systematically analyze mechanisms studies of LT-WGS,rational catalyst design strategies,and recent frontier advances in the development of highly efficient catalysts.Furthermore,this review provides actionable insights for refining catalyst architectures,enhancing operational efficiency,elucidating reaction pathways,and pioneering hybrid technologies,all contributing to further advancements in this field.
基金financial support from the National Natural Science Foundation of China(22078326,21878305).
文摘In this study,the effects of reaction parameters on the deep-reduction and carbonization process of WO_(2)-Co to WC-Co were studied.The results indicate that the oxygen loss rate of WO_(2) is positively correlated with temperature and methane partial pressure.The partial pressure of methane has no significant effect on the formation rate of WC.The carbon content and particle size of the product increase with the increase of CH_(4) partial pressure.By synergistically regulating the reaction temperature to 950℃,the CH_(4) partial pressure to 1.25%,and the reaction time to 60 min,ultrafine WC-Co powder without η phase can be obtained.The particle size of the composite powder is 128 nm,with total carbon content of 6.16%,free carbon content of 0.4%,and residual oxygen content of 0.05%,respectively.The growth rate relationship of tungsten carbide is as follows:δ(t)=1.21×10^(-13)exp(-12809.72/T)√t.
基金support provided by the Natural Science Foundation of Science and Technology Department of Sichuan Province,China(2024NSFSC0154)the Open Fund for Research Platform of the School of New Energy and Materials,Southwest Petroleum University(2022SCYYQKCCL010).
文摘Annular channeling has seriously troubled deep oil and gas exploitation,and the reduction of hydrostatic pressure of cement slurry in the waiting stage is considered one of the main causes of early annular channeling.However,at present,there is still a lack of sufficient research on and understanding of the relationship between the time-varying law of hydrostatic pressure of cement slurry and the early hydration process in different well sections,especially in high-temperature well sections.Therefore,in this paper,a hydrostatic pressure measurement experiment of cement slurry at low temperature(50-90℃)and high temperature(120-180℃)was carried out using a self-developed hydrostatic pressure measurement device of cement slurry.Then,the cement slurry cured at 90℃ for 1-8 h was sampled by the freeze-drying method,and XRD and TG experiments were carried out.The results show that the hydrostatic curves of low and high temperatures both show a trend of rapid increase first,then remain stable,and then decrease rapidly.With an increase in temperature,the time of the stable and falling segments of the hydrostatic curve of the cement slurry gradually decreases.By fitting the rapid pressure drop time points of cement slurry at different temperatures,it can be determined that the rapid pressure drop time and temperature show a functional relationship.The XRD and TG results of different curing times at 90℃ were analyzed.It can be seen that in the early stage of the hydration induction period,the connection between cement particles is not close,and the hydrostatic pressure of the cement slurry column remains stable.As the hydration process enters the acceleration period,the cement particles crosslink with each other through hydration products to form a bridge structure,and the hydrostatic pressure of the cement paste begins to decrease.This shows that the pressure drop time can be controlled by regulating the hydration process to provide theoretical guidance for cement slurry preparation and slurry column design in cementing engineering.
基金financially supported by the National Natural Science Foundation of China(Grant nos.21376001,21576028 and 21506012)。
文摘Carbon-fueled solid oxide fuel cells(CF-SOFCs)can electrochemically convert the chemical energy in carbon into electricity,which demonstrate both superior electrical efficiency and fuel utilisation compared to all other types of fuel cells.However,using solid carbon as the fuel of SOFCs also faces some challenges,the fluid mobility and reactive activity of carbon-based fuels are much lower than those of gaseous fuels.Therefore,the anode reaction kinetics plays a crucial role in determining the electrochemical performance of CF-SOFCs.Herein,the progress of various anodes in CF-SOFCs is reviewed from the perspective of material compositions,electrochemical performance and microstructures.Challenges faced in developing high performance anodes for CF-SOFCs are also discussed.
基金This work was supported by the National Natural Science Foundation of China （No.20776089） and the New Century Excellent Talents Program of Ministry of Education （No.NCET-05-0783）. The State Key Laboratory of Polymer Materials Engineering in Sichuan University was acknowledged for providing dmol3 modules and Prof. Ying Xue, Xiang-yuan Li, and Quan Zhu were grateful for the useful discussions.
文摘The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like screening model. Association pathway and dissocia-tion pathway were investigated by the comparison of several energies. The cleavage energy of Pd（PR3）2 complex was calculated, as well as the oxidative addition reaction barrier energy of Pd（PR3）n （n=1,2） with aryl bromide in N,N-dimethylformamide solvent. This study proved that the ligands volume possessed a great impact on the mechanism of oxidative addition： less bulky ligand palladium associated with aryl bromide via two donor ligands,but larger bulky ligand palladium coordinated via monoligand.
基金Project(N100302002)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(20100471467)supported by the China Postdoctoral Science Foundation
文摘Zirconia-mullite-corundum composites were successfully prepared from fly ash,zircon and alumina powder by a reaction sintering process.The phase and microstructure evolutions of the composite synthesized at desired temperatures of 1 400,1 500 and 1 600°C for 4 h were characterized by X-ray diffractometry and scanning electronic microscopy,respectively.The influences of sintering temperature on shrinkage ratio,apparent porosity and bulk density of the synthesized composite were investigated.The formation process of the composites was discussed in detail.The results show that the zirconia-mullite-corundum composites with good sintering properties can be prepared at 1 600°C for 4 h.Zirconia particles can be homogeneously distributed in mullite matrix,and the zirconia particles are around 5μm.The formation process of zirconia-mullite-corundum composites consists of decomposition of zircon and mullitization process.
基金financially supported by the Key-Area Research and Development Program of Guangdong Province(2019B010937001)the National Natural Science Foundation of China(50702022,51577070,51702056 and U1601208)+1 种基金Natural Science Foundation of Guangdong Province(2019A1515012129)Science and Technology Planning Project of Guangdong Province(2016B090932005)。
文摘Currently,photocatalytic water splitting is regarded as promising technology in renewable energy generation.However,the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers.Rational designed the structure and doping elements become important alternative routes to improve the performance of photocatalyst.In this work,we rational designed oxygen-doped graphitic carbon nitride(OCN)nanotubes derived from supermolecular intermediates for photocata lytic water splitting.The as prepared OCN nanotubes exhibit an outstanding hydrogen evolution rate of 73.84μmol h^(-1),outperforming the most of reported one dimensional(1D)g-C_(3)N_(4) previously.Due to the rational oxygen doping,the band structure of g-C_(3)N_(4) is meliorated,which can narrow the band gap and reduce the recombination rate of photogene rated carriers.Furthermore,the hollow nanotube structure of OCN also provide multiple diffuse reflection during photocata lytic reaction,which can significantly promote the utilization capacity of visible light and enhance the photocatalytic water splitting performance.It is believed that our work not only rationally controls the nanostructure,but also introduces useful heteroatom into the matrix of photocatalyst,which provides an effective way to design high-efficiency g-C_(3)N_(4) photocatalyst.
基金This work was supported by the National Natural Science Foundation of China (No. 50432010, 50372037).
文摘In situ Al2O3 whiskers reinforced Ti-Al intermetallic composites were fabricated at ~1200℃ by reaction sintering of cold-consolidated fillets consisting mainly of Ti, Al, and different additives. The phases and microstructures of the sintered composites were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The process of synthesis was investigated using differential thermal analysis (DTA). The effects of processing parameters and additives on the microstructures of the composites and the development of whisker were examined. It is found that the morphology of the whisker is strongly influenced by the additives, the exothermal reaction process, and the processing parameters.
基金supported by the Open Project Program of State Key Laboratory of Petroleum Pollution Control(No.PPC2017010)CNPC Research Institute of Safety and Environmental Technology,and State Key Laboratory of Solid Waste Reuse for Building Materials(SWR2017002)+2 种基金National Natural Science Foundation of China(No.51108453)Program for New Century Excellent Talents in University(No.NCET120967)the Fundamental Research Funds for the Central Universities(No.2009QH03)
文摘Non-thermal plasma technology is a new type of odor treatment processing.We deal with H2Sfrom waste gas emission using non-thermal plasma generated by dielectric barrier discharge.On the basis of two criteria,removal efficiency and absolute removal amount,we deeply investigate the changes in electrical parameters and process parameters,and the reaction process of the influence of ozone on H2S gas removal.The experimental results show that H2S removal efficiency is proportional to the voltage,frequency,power,residence time and energy efficiency,while it is inversely proportional to the initial concentration of H2S gas,and ozone concentration.This study lays the foundations of non-thermal plasma technology for further commercial application.
