The steady-state kinetics for complete oxidation of benzene over has been investigated by the external recycling reactor. The kinetics equation was described by the L-H model of adsorption of benzene and oxygen with t...The steady-state kinetics for complete oxidation of benzene over has been investigated by the external recycling reactor. The kinetics equation was described by the L-H model of adsorption of benzene and oxygen with the inhibition of carbon dioxide. The parameters of the kinetics model were estimated by the method of orthogonal design. The heats of adsorption of benzene, oxygen and carbon dioxide were determined by the method of gas-adsorption chromatography. The details of oscillations of complete oxidation of benzene were investigated.展开更多
Royal palm tree peroxidase (RPTP) has been isolated to homogeneity from leaves of Roystonea regia palm trees. The enzyme purification steps included homogenization, (NH4)SO4 precipitation, extraction of palm leaf colo...Royal palm tree peroxidase (RPTP) has been isolated to homogeneity from leaves of Roystonea regia palm trees. The enzyme purification steps included homogenization, (NH4)SO4 precipitation, extraction of palm leaf colored compounds and consecutive chromatography on Phenyl-Sepharose, TSK-Gel DEAE-5PW and Superdex-200. The novel peroxidase was characterized as having a molecular weight of 48.2 ± 3.0 kDa and an isoelectric point pI 5.4 ± 0.1. The enzyme forms dimers in solution with approximate molecular weight of 92 ± 2 kDa. Here we investigated the steady-state kinetic mechanism of the H2O2-supported oxidation of different organic substrates by RPTP. The results of the analysis of the initial rates vs. H2O2 and reducing substrate concentrations were seen to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach used expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters KmH2O2, KmAH2, kcat, KSIH2O2, KSIAH2 and of the microscopic rate constants k1 and k3 of the shared three-step peroxidase catalytic cycle. Furthermore, the concentration and time-dependences and the mechanism of the suicide inactivation of RPTP by hydrogen peroxide were studied kinetically with guaiacol as co-substrate. The turnover number (r) of H2O2 required to complete the inactivation of the enzyme was 2154 ± 100 and the apparent rate constants of catalysis 185 s–1 and 18 s–1.展开更多
Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting t...Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting two greenhouse gases(methane and carbon dioxide)into syngas and its promising industrial applications.Nickel(Ni)-based catalysts,with high catalytic activity,low cost,and abundant resources,are considered ideal candidates for industrial applications.In this article,three reaction kinetic models were briefly introduced,namely the Power-Law(PL)model,the Eley-Rideal(ER)model,and the Langmuir-Hinshelwood-Hougen-Watson(LHHW)model.Based on the LHHW model,the reaction kinetics and mechanisms of different catalytic systems were systematically discussed,including the properties of supports,the doping of noble metals and transition metals,the role of promoters,and the influence of the geometric and electronic structures of Ni on the reaction mechanism.Furthermore,the kinetics of carbon deposition and elimination on various catalysts were analyzed.Based on the reaction rate expressions for carbon elimination,the reasons for the high activity of transition metal iron(Fe)-doped catalysts and core-shell structured catalysts in carbon elimination were explained.Based on the detailed collation and comparative analysis of the reaction mechanisms and kinetic characteristics across diverse Ni-based catalytic systems,a theoretical guidance for the designing of high-performance catalysts was provided in this work.展开更多
The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623−773 K and pressure ranges of 10−10000 Pa.The experimental results reveal that the evaporation rate...The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623−773 K and pressure ranges of 10−10000 Pa.The experimental results reveal that the evaporation rate increases with increasing temperature and decreasing pressure.Surface reaction control dominates at low pressures(<100 Pa),whereas diffusion control dominates at high pressures(>5000 Pa).The evaporation behavior is successfully described by an Arrhenius-type model for temperature dependence and Logistic model for pressure dependence.Key kinetic parameters,including the critical pressure,maximum evaporation rate and evaporation coefficient,were calculated.The evaporation coefficient varies between 0.010 and 0.223,and the critical pressures vary between 281 and 478 Pa with temperature.展开更多
The hydrogen reduction kinetics of tungsten trioxide(WO_(3))was investigated via non-isothermal thermogravimetric analysis.Under the local gas-solid reduction conditions,the particle morphology of tungsten powders was...The hydrogen reduction kinetics of tungsten trioxide(WO_(3))was investigated via non-isothermal thermogravimetric analysis.Under the local gas-solid reduction conditions,the particle morphology of tungsten powders was found to be consistent with that of raw material WO_(3).The removal of oxygen from tungsten oxide during hydrogen reduction led to the formation of porous structures between the reduced particles,which were obviously different from the polyhedral single-crystal configuration of tungsten powders obtained via chemical vapor deposition.Moreover,the two-stage hydrogen reduction mechanisms of WO_(3) under the local gas-solid reduction conditions can be described using the composite autocatalytic function.The activation energies of the first and second stages of the hydrogen reduction of WO_(3) were determined to be 121 and 135 kJ/mol,respectively.展开更多
The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light...The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light absorption to charge separation,transport,and ultimately charge collection.Dynamic changes in crystallization and aggregation states can also disrupt the microstructure of the active layer,thus shortening the lifetime of the cell.In this study,a morphology modulation strategy is proposed to regulate the crystallization kinetics of non-fullerene acceptors by employing the polymer molecule PYIT as a nucleating agent.An appropriate amount of PYIT was first completely dissolved with the non-fullerene acceptor Y6 and left to stand for 24 h,followed by the fabrication of layer-by-layer processed OSCs.Experiments demonstrated that high crystallinity of PYIT allows it to act as a crystallization nucleus,promoting the crystallization,orientation consistency,and ordered stacking of the acceptor.These nanoscale structural optimizations facilitate efficient charge transport,enhance exciton dissociation efficiency,and suppress unfavorable energetic disorder.Consequently,not only was the power conversion efficiency(PCE)of D18-Cl/Y6-based layer-by-layer processed OSC increased from 18.08%to 19.13%,but the atmospheric stability and long-term lifetime of the OSCs were also significantly improved.Notably,this strategy is also applicable to indoor OSCs,and the PYIT-optimized device can achieve a PCE of 27.0%under 1000 lux light-emitting diode(LED,3200K)irradiation,which is superior to that of the control device(24.2%).This work develops a crystal engineering strategy that is able to simultaneously optimize the microscopic morphology and charge dynamics properties in OSCs,thereby achieving simultaneous improvement in efficiency and stability.展开更多
In order to explore the effects of CaO,lignite dust and sawdust on the drying characteristics ofmunicipal sludge at different concentrations,a three-factor three-level regression experiment was carried out based on th...In order to explore the effects of CaO,lignite dust and sawdust on the drying characteristics ofmunicipal sludge at different concentrations,a three-factor three-level regression experiment was carried out based on the results of thermogravimetric experiment and single factor experiment.By fitting three common mathematical models,the Page model with the highest fitting degree was selected to determine the most suitable mathematical model to describe the municipal sludge drying process.In addition,the Box-Behnken design principle in the response surface method was used to analyze the interaction of three factors on the drying characteristics of municipal sludge.The results of the study show that below 100℃is the optimal drying temperature range for municipal sludge.The results of single factor experiments showed that the order of influence of the three factors on sludge drying time was CaO concentration>sawdust concentration>lignite dust concentration.In the single factor experiment,the optimal process parameterswere CaOconcentration 3%,lignite powder concentration 7%,and sawdust concentration 7%.In themulti-factor interaction analysis,the interaction between CaO and sawdust had the most significant effect on the reduction of drying time,and the order of influence was as follows:CaO interaction with sawdust>lignite dust interaction with sawdust>CaO interaction with lignite powder.Further analysis showed that the optimal process ratio was 3%CaO concentration and 3%sawdust concentration.展开更多
This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,5...This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.展开更多
In this study,copper extraction from low-grade oxide-sulfide ores was investigated using a leaching method combined with response surface methodology(RSM)to optimize operational conditions and assess leaching kinetics...In this study,copper extraction from low-grade oxide-sulfide ores was investigated using a leaching method combined with response surface methodology(RSM)to optimize operational conditions and assess leaching kinetics.Given copper's extensive industrial applications,sustainable recovery from low-grade ores is critical.Five key parameters-acid concentration,leaching time,particle size,temperature,and solids percentage-were identified as major influences on copper recovery.The results revealed that leaching time and solids percentage,along with interactions between temperature-time and temperature-solids percentage,had the most significant effects.Optimal conditions for 80% copper recovery while minimizing iron recovery below 3% included an acid concentration of 1.21 mol L^(-1),a leaching time of 108 min,a particle size of 438μm,a temperature of 45℃,and a solids percentage of 18.2%.Leaching kinetics were analyzed using shrinking core models,with the Dickinson model best describing the process,showing an activation energy of 32.63 kJ mol^(-1),indicative of mixed diffusion and chemical reaction control.The final kinetic model effectively predicted the influence of key parameters.These findings highlight the importance of optimizing process variables and selecting suitable kinetic models to enhance extraction efficiency,reduce costs,and improve sustainability in copper recovery.展开更多
Layered double hydroxides(LDHs)hold great promise as cathode materials for aqueous zinc-ion batteries(AZIBs).Nevertheless,they also face challenges of sluggish kinetics and rapid capacity loss.Herein,a conformational ...Layered double hydroxides(LDHs)hold great promise as cathode materials for aqueous zinc-ion batteries(AZIBs).Nevertheless,they also face challenges of sluggish kinetics and rapid capacity loss.Herein,a conformational entropy regulation strategy has been applied to surmount the shortcomings.A medium-entropy iron-based metal organic framework(MIL-88)derived NiCoFeInZnV-based layered double hydroxide with carbon loaded(ME-NiCoFeInZnV-LDH/C)has been first proposed and prepared with a designed method.The increased entropy optimizes electron conductivity and alleviates structure alteration and diffusion barrier during interactions with charge carriers,due to electron-induced effect and“cocktail”effect.Moreover,the nanosheet assembled hollow prismatic structures could homogenize flux distribution and electric field distribution.Therefore,the electrochemical kinetics,crystal structure stability,and activity could be dramatically improved.Leveraging the advantages of structure and composition regulation,Zn||ME-NiCoFeInZnV-LDH/C zinc battery delivers high specific capacities,rate performance,and cycling stability.This work proposes a novel and feasible medium-entropy strategy to prepare a high-performance cathode for advanced AZIBs,which is of prominent significance for the development of charge storage devices.展开更多
Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed control.Thus,fault diagnosis of gas turbine actuators has attracted considerable attention,from b...Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed control.Thus,fault diagnosis of gas turbine actuators has attracted considerable attention,from both academia and industry.However,the extensive literature that exists on this topic does not address identifying the severity of actuator faults and focuses mainly on actuator fault detection and isolation.In addition,previous studies of actuator fault identification have not dealt with multiple concurrent faults in real time,especially when these are accompanied by sudden failures under dynamic conditions.This study develops component-level models for fault identification in four typical actuators used in high-bypass ratio turbofan engines under both dynamic and steady-state conditions and these are then integrated with the engine performance model developed by the authors.The research results reported here present a novel method of quantifying actuator faults using dynamic effect compensation.The maximum error for each actuator is less than0.06%and 0.07%,with average computational time of less than 0.0058 s and 0.0086 s for steady-state and transient cases,respectively.These results confirm that the proposed method can accurately and efficiently identify concurrent actuator fault for an engine operating under either transient or steady-state conditions,even in the case of a sudden malfunction.The research results emonstrate the potential benefit to emergency response capabilities by introducing this method of monitoring the health of aero engines.展开更多
In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodyn...In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.展开更多
Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment ...Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.展开更多
This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that ...This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.展开更多
Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Bori...Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Boriding process is one of the ways to modify and increase the surface properties.The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316 L SS.In this study,the growth kinetic mechanism was evaluated for AM 316 L SS.Pack boriding was applied at 850,900 and 950℃,each for 2,4 and 6 h.The thickness of the boride layers ranged from(1.8±0.3)μm to(27.7±2.2)μm.A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe_(2)B phase layers.The activation energy(Q)values for boron diffusion in FeB layer,Fe_(2)B layer,and dual FeB+Fe_(2)B layer were found to be 256.56,161.61 and 209.014 kJ/mol,respectively,which were higher than the conventional 316 L SS.The findings might provide and open new directions and approaches for applications of additively manufactured steels.展开更多
Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batterie...Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batteries for mitigating range anxiety and slow charging issues in new energy vehicles.Herein,a thick silicon/carbon composite electrode with vertically aligned channels in the thickness direction(VC-SC)is constructed by employing a bubble formation method.Both experimental characterizations and theoretical simulations confirm that the obtained vertical channel structure can effectively address the problem of sluggish ion transport caused by high tortuosity in conventional thick electrodes,conspicuously enhance reaction kinetics,reduce polarization and side reactions,mitigate stress,increase the utilization of active materials,and promote cycling stability of the thick electrode.Consequently,when paired with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),the VC-SC||NCM622 pouch type full cell(~6.0 mAh cm^(-2))exhibits significantly improved rate performance and capacity retention compared with the SC||NCM622 full cell with the conventional silicon/carbon composite electrode without channels(SC)as the anode.The assembled VC-SC||NCM622 pouch full cell with a high energy density of 490.3 Wh kg^(-1)also reveals a remarkable fast charging capability at a high current density of 2.0 mA cm^(-2),with a capacity retention of 72.0%after 500 cycles.展开更多
Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cok...Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.展开更多
The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and h...The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and high regeneration efficiency.Different with the liquid-liquid phase change solvent,the reaction kinetics of CO_(2)capture into solid-liquid biphasic solvent was rarely studied.In the present work,the reaction kinetics of CO_(2)absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor.The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism.The overall reaction rate constant(kov)and the enhancement factor(E)of CO_(2)absorption both increased with increasing temperature.The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading,so the higher reaction temperature was conducive to the absorption,and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.展开更多
Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and init...Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.展开更多
Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully u...Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully understood yet,resulting in a lack of theoretical basis for synthesis process improvement.Here,the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory.Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions.Based on theoretical reaction rate ratios,reaction pathways were selected,and a simplified reaction network was derived.It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions.The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data.This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.展开更多
基金Supported by the National Sciences Fundation of China.
文摘The steady-state kinetics for complete oxidation of benzene over has been investigated by the external recycling reactor. The kinetics equation was described by the L-H model of adsorption of benzene and oxygen with the inhibition of carbon dioxide. The parameters of the kinetics model were estimated by the method of orthogonal design. The heats of adsorption of benzene, oxygen and carbon dioxide were determined by the method of gas-adsorption chromatography. The details of oscillations of complete oxidation of benzene were investigated.
文摘Royal palm tree peroxidase (RPTP) has been isolated to homogeneity from leaves of Roystonea regia palm trees. The enzyme purification steps included homogenization, (NH4)SO4 precipitation, extraction of palm leaf colored compounds and consecutive chromatography on Phenyl-Sepharose, TSK-Gel DEAE-5PW and Superdex-200. The novel peroxidase was characterized as having a molecular weight of 48.2 ± 3.0 kDa and an isoelectric point pI 5.4 ± 0.1. The enzyme forms dimers in solution with approximate molecular weight of 92 ± 2 kDa. Here we investigated the steady-state kinetic mechanism of the H2O2-supported oxidation of different organic substrates by RPTP. The results of the analysis of the initial rates vs. H2O2 and reducing substrate concentrations were seen to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach used expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters KmH2O2, KmAH2, kcat, KSIH2O2, KSIAH2 and of the microscopic rate constants k1 and k3 of the shared three-step peroxidase catalytic cycle. Furthermore, the concentration and time-dependences and the mechanism of the suicide inactivation of RPTP by hydrogen peroxide were studied kinetically with guaiacol as co-substrate. The turnover number (r) of H2O2 required to complete the inactivation of the enzyme was 2154 ± 100 and the apparent rate constants of catalysis 185 s–1 and 18 s–1.
基金Supported by Innovation Capability Support Program of Shaanxi(2024RS-CXTD-53,2024ZC-KJXX-096)the Key R&D Program of Shaanxi Province(2022QCY-LL-69)Xi’an Science and Technology Project(24GXFW0089)。
文摘Under the backdrop of“Carbon Peak and Carbon Neutrality”(dual carbon)goal in China,the methane-carbon dioxide reforming reaction has attracted considerable attention due to its environmental benefits of converting two greenhouse gases(methane and carbon dioxide)into syngas and its promising industrial applications.Nickel(Ni)-based catalysts,with high catalytic activity,low cost,and abundant resources,are considered ideal candidates for industrial applications.In this article,three reaction kinetic models were briefly introduced,namely the Power-Law(PL)model,the Eley-Rideal(ER)model,and the Langmuir-Hinshelwood-Hougen-Watson(LHHW)model.Based on the LHHW model,the reaction kinetics and mechanisms of different catalytic systems were systematically discussed,including the properties of supports,the doping of noble metals and transition metals,the role of promoters,and the influence of the geometric and electronic structures of Ni on the reaction mechanism.Furthermore,the kinetics of carbon deposition and elimination on various catalysts were analyzed.Based on the reaction rate expressions for carbon elimination,the reasons for the high activity of transition metal iron(Fe)-doped catalysts and core-shell structured catalysts in carbon elimination were explained.Based on the detailed collation and comparative analysis of the reaction mechanisms and kinetic characteristics across diverse Ni-based catalytic systems,a theoretical guidance for the designing of high-performance catalysts was provided in this work.
基金Yunnan Fundamental Research Project,China(No.202201BE070001-056)。
文摘The volatilization characteristics and kinetic mechanisms of arsenic were investigated in the temperature range of 623−773 K and pressure ranges of 10−10000 Pa.The experimental results reveal that the evaporation rate increases with increasing temperature and decreasing pressure.Surface reaction control dominates at low pressures(<100 Pa),whereas diffusion control dominates at high pressures(>5000 Pa).The evaporation behavior is successfully described by an Arrhenius-type model for temperature dependence and Logistic model for pressure dependence.Key kinetic parameters,including the critical pressure,maximum evaporation rate and evaporation coefficient,were calculated.The evaporation coefficient varies between 0.010 and 0.223,and the critical pressures vary between 281 and 478 Pa with temperature.
基金supported by the National Key Research&Development Program of China(No.2022YFC2904905)the National Natural Science Foundation of China(No.52274400)+1 种基金the Project of Zhongyuan Critical Metals Laboratory,China(No.GJJSGFZD202302)the Science and Technology Project of Henan Province,China(No.232102230044)。
文摘The hydrogen reduction kinetics of tungsten trioxide(WO_(3))was investigated via non-isothermal thermogravimetric analysis.Under the local gas-solid reduction conditions,the particle morphology of tungsten powders was found to be consistent with that of raw material WO_(3).The removal of oxygen from tungsten oxide during hydrogen reduction led to the formation of porous structures between the reduced particles,which were obviously different from the polyhedral single-crystal configuration of tungsten powders obtained via chemical vapor deposition.Moreover,the two-stage hydrogen reduction mechanisms of WO_(3) under the local gas-solid reduction conditions can be described using the composite autocatalytic function.The activation energies of the first and second stages of the hydrogen reduction of WO_(3) were determined to be 121 and 135 kJ/mol,respectively.
基金supported by the National Natural Science Foundation of China (NSFC grant no. 62474028, 52130304, and62222503)the Natural Science Foundation of Sichuan Province(2025ZNSFSC0037, 2025ZNSFSC1460, and 2024NSFSC1447)+1 种基金the National Key R and D Program of China (2023YFB2604101)sponsored by the Sichuan Province Key Laboratory of Display Science and Technology
文摘The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light absorption to charge separation,transport,and ultimately charge collection.Dynamic changes in crystallization and aggregation states can also disrupt the microstructure of the active layer,thus shortening the lifetime of the cell.In this study,a morphology modulation strategy is proposed to regulate the crystallization kinetics of non-fullerene acceptors by employing the polymer molecule PYIT as a nucleating agent.An appropriate amount of PYIT was first completely dissolved with the non-fullerene acceptor Y6 and left to stand for 24 h,followed by the fabrication of layer-by-layer processed OSCs.Experiments demonstrated that high crystallinity of PYIT allows it to act as a crystallization nucleus,promoting the crystallization,orientation consistency,and ordered stacking of the acceptor.These nanoscale structural optimizations facilitate efficient charge transport,enhance exciton dissociation efficiency,and suppress unfavorable energetic disorder.Consequently,not only was the power conversion efficiency(PCE)of D18-Cl/Y6-based layer-by-layer processed OSC increased from 18.08%to 19.13%,but the atmospheric stability and long-term lifetime of the OSCs were also significantly improved.Notably,this strategy is also applicable to indoor OSCs,and the PYIT-optimized device can achieve a PCE of 27.0%under 1000 lux light-emitting diode(LED,3200K)irradiation,which is superior to that of the control device(24.2%).This work develops a crystal engineering strategy that is able to simultaneously optimize the microscopic morphology and charge dynamics properties in OSCs,thereby achieving simultaneous improvement in efficiency and stability.
基金the National Natural Science Foundation of China,grant number 52406074the China Postdoctoral Science Foundation under Grant Number 2025T180171+1 种基金the Natural Science Foundation of Guangdong Province(2025A1515011270)the China Southern Power Grid Technology Project(GDKJXM20231415/030100KC23120104).
文摘In order to explore the effects of CaO,lignite dust and sawdust on the drying characteristics ofmunicipal sludge at different concentrations,a three-factor three-level regression experiment was carried out based on the results of thermogravimetric experiment and single factor experiment.By fitting three common mathematical models,the Page model with the highest fitting degree was selected to determine the most suitable mathematical model to describe the municipal sludge drying process.In addition,the Box-Behnken design principle in the response surface method was used to analyze the interaction of three factors on the drying characteristics of municipal sludge.The results of the study show that below 100℃is the optimal drying temperature range for municipal sludge.The results of single factor experiments showed that the order of influence of the three factors on sludge drying time was CaO concentration>sawdust concentration>lignite dust concentration.In the single factor experiment,the optimal process parameterswere CaOconcentration 3%,lignite powder concentration 7%,and sawdust concentration 7%.In themulti-factor interaction analysis,the interaction between CaO and sawdust had the most significant effect on the reduction of drying time,and the order of influence was as follows:CaO interaction with sawdust>lignite dust interaction with sawdust>CaO interaction with lignite powder.Further analysis showed that the optimal process ratio was 3%CaO concentration and 3%sawdust concentration.
文摘This study explores the thin-layer convective solar drying of Marrubium vulgare L.leaves under conditions typical of sun-rich semi-arid climates.Drying experiments were conducted at three inlet-air temperatures(40℃,50℃,60℃)and two air velocities(1.5 and 2.5 m·s^(-1))using an indirect solar dryer with auxiliary temperature control.Moisture-ratio data were fitted with eight widely used thin-layer models and evaluated using correlation coefficient(r),root-mean-square error(RMSE),and Akaike information criterion(AIC).A complementary heattransfer analysis based on Reynolds and Prandtl numbers with appropriate Nusselt correlations was used to relate flow regime to drying performance,and an energy balance quantified the relative contributions of solar and auxiliary heat.The logarithmic model consistently achieved the lowest RMSE/AIC with r>0.99 across all conditions.Higher temperature and air velocity significantly reduced drying time during the decreasing-rate period,with no constantrate stage observed.On average,solar input supplied the large majority of the thermal demand,while the auxiliary heater compensated short irradiance drops to maintain setpoints.These findings provide a reproducible dataset and a modelling benchmark for M.vulgare leaves,and they support energy-aware design of hybrid solar dryers formedicinal plants in sun-rich regions.
基金Open Access funding enabled and organized by Projekt DEAL.
文摘In this study,copper extraction from low-grade oxide-sulfide ores was investigated using a leaching method combined with response surface methodology(RSM)to optimize operational conditions and assess leaching kinetics.Given copper's extensive industrial applications,sustainable recovery from low-grade ores is critical.Five key parameters-acid concentration,leaching time,particle size,temperature,and solids percentage-were identified as major influences on copper recovery.The results revealed that leaching time and solids percentage,along with interactions between temperature-time and temperature-solids percentage,had the most significant effects.Optimal conditions for 80% copper recovery while minimizing iron recovery below 3% included an acid concentration of 1.21 mol L^(-1),a leaching time of 108 min,a particle size of 438μm,a temperature of 45℃,and a solids percentage of 18.2%.Leaching kinetics were analyzed using shrinking core models,with the Dickinson model best describing the process,showing an activation energy of 32.63 kJ mol^(-1),indicative of mixed diffusion and chemical reaction control.The final kinetic model effectively predicted the influence of key parameters.These findings highlight the importance of optimizing process variables and selecting suitable kinetic models to enhance extraction efficiency,reduce costs,and improve sustainability in copper recovery.
基金the funding support from the National Natural Science Foundation of China(Grant No.52202217,52471222)the Natural Science Foundation of Jilin Province(Grant No.YDZJ202201ZYTS375).
文摘Layered double hydroxides(LDHs)hold great promise as cathode materials for aqueous zinc-ion batteries(AZIBs).Nevertheless,they also face challenges of sluggish kinetics and rapid capacity loss.Herein,a conformational entropy regulation strategy has been applied to surmount the shortcomings.A medium-entropy iron-based metal organic framework(MIL-88)derived NiCoFeInZnV-based layered double hydroxide with carbon loaded(ME-NiCoFeInZnV-LDH/C)has been first proposed and prepared with a designed method.The increased entropy optimizes electron conductivity and alleviates structure alteration and diffusion barrier during interactions with charge carriers,due to electron-induced effect and“cocktail”effect.Moreover,the nanosheet assembled hollow prismatic structures could homogenize flux distribution and electric field distribution.Therefore,the electrochemical kinetics,crystal structure stability,and activity could be dramatically improved.Leveraging the advantages of structure and composition regulation,Zn||ME-NiCoFeInZnV-LDH/C zinc battery delivers high specific capacities,rate performance,and cycling stability.This work proposes a novel and feasible medium-entropy strategy to prepare a high-performance cathode for advanced AZIBs,which is of prominent significance for the development of charge storage devices.
基金support by the National Natural Science Foundation of China(Grant No.52402520)。
文摘Actuator faults can be critical in turbofan engines as they can lead to stall,surge,loss of thrust and failure of speed control.Thus,fault diagnosis of gas turbine actuators has attracted considerable attention,from both academia and industry.However,the extensive literature that exists on this topic does not address identifying the severity of actuator faults and focuses mainly on actuator fault detection and isolation.In addition,previous studies of actuator fault identification have not dealt with multiple concurrent faults in real time,especially when these are accompanied by sudden failures under dynamic conditions.This study develops component-level models for fault identification in four typical actuators used in high-bypass ratio turbofan engines under both dynamic and steady-state conditions and these are then integrated with the engine performance model developed by the authors.The research results reported here present a novel method of quantifying actuator faults using dynamic effect compensation.The maximum error for each actuator is less than0.06%and 0.07%,with average computational time of less than 0.0058 s and 0.0086 s for steady-state and transient cases,respectively.These results confirm that the proposed method can accurately and efficiently identify concurrent actuator fault for an engine operating under either transient or steady-state conditions,even in the case of a sudden malfunction.The research results emonstrate the potential benefit to emergency response capabilities by introducing this method of monitoring the health of aero engines.
基金financially supported by the National Natural Science Foundation of China(No.52174342)Beijing Natural Sci-ence Foundation(No.2232044)Beijing Municipal Education Commission Research Plan General Project(No.KM202410005009).
文摘In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.
基金supported by the National Natural Science Foundation of China(U22A20120,52071135,51871090,U1804135,and 52301269)the Natural Science Foundation of Hebei Province for Innovation Groups Program(C2022203003)Fundamental Research Funds for the Universities of Henan Province(NSFRF220201).
文摘Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.
基金supported by the National Natural Science Foundation of China(No.52271089)the financial support from the C hina Postdoctoral Science Foundation(No.2023M732192)。
文摘This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.
文摘Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Boriding process is one of the ways to modify and increase the surface properties.The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316 L SS.In this study,the growth kinetic mechanism was evaluated for AM 316 L SS.Pack boriding was applied at 850,900 and 950℃,each for 2,4 and 6 h.The thickness of the boride layers ranged from(1.8±0.3)μm to(27.7±2.2)μm.A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe_(2)B phase layers.The activation energy(Q)values for boron diffusion in FeB layer,Fe_(2)B layer,and dual FeB+Fe_(2)B layer were found to be 256.56,161.61 and 209.014 kJ/mol,respectively,which were higher than the conventional 316 L SS.The findings might provide and open new directions and approaches for applications of additively manufactured steels.
基金National Key R&D Program of China,Grant/Award Number:2023YFB2503900National Natural Science Foundation of China,Grant/Award Number:12172143Shenzhen Science and Technology Program,Grant/Award Numbers:JCYJ20220818100418040,JCYJ20220530160816038。
文摘Constructing silicon(Si)-based composite electrodes that possess high energy density,long cycle life,and fast charging capability simultaneously is critical for the development of high performance lithium-ion batteries for mitigating range anxiety and slow charging issues in new energy vehicles.Herein,a thick silicon/carbon composite electrode with vertically aligned channels in the thickness direction(VC-SC)is constructed by employing a bubble formation method.Both experimental characterizations and theoretical simulations confirm that the obtained vertical channel structure can effectively address the problem of sluggish ion transport caused by high tortuosity in conventional thick electrodes,conspicuously enhance reaction kinetics,reduce polarization and side reactions,mitigate stress,increase the utilization of active materials,and promote cycling stability of the thick electrode.Consequently,when paired with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),the VC-SC||NCM622 pouch type full cell(~6.0 mAh cm^(-2))exhibits significantly improved rate performance and capacity retention compared with the SC||NCM622 full cell with the conventional silicon/carbon composite electrode without channels(SC)as the anode.The assembled VC-SC||NCM622 pouch full cell with a high energy density of 490.3 Wh kg^(-1)also reveals a remarkable fast charging capability at a high current density of 2.0 mA cm^(-2),with a capacity retention of 72.0%after 500 cycles.
基金supported by National Natural Science Foundation of China(22178002,22178001)Natural Science Foundation of Anhui Province(2308085Y19)Excellent Youth Research Project of Anhui Provincial Department of Education(2022AH030045).
文摘Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.
基金supported by the National Natural Science Foundation of China(No.22276064)the Youth Innovation Grant of Xiamen,Fujian Province(No.3502Z20206006)+1 种基金the MOE Key Laboratory of Resources and Environmental System Optimization(No.KLRE-KF202205)Fujian Science and Technology Project(No.2022Y3007).
文摘The non-aqueous solid-liquid biphasic solvent of 2-amino-2-methyl-1-propanol(AMP)/piperazine(PZ)/dipropylene glycol dimethyl ether(DME)features a high CO_(2)absorption loading,favorable phase separation behavior and high regeneration efficiency.Different with the liquid-liquid phase change solvent,the reaction kinetics of CO_(2)capture into solid-liquid biphasic solvent was rarely studied.In the present work,the reaction kinetics of CO_(2)absorption into AMP/PZ/DME solid-liquid biphasic solvent was investigated into the double stirred kettle reactor.The absorption reaction followed a pseudo-first-order kinetic model according to the zwitterion mechanism.The overall reaction rate constant(kov)and the enhancement factor(E)of CO_(2)absorption both increased with increasing temperature.The total mass transfer resistance of the absorbent decreased with increasing temperature and increased with increasing absorption loading,so the higher reaction temperature was conducive to the absorption,and the liquid phase mass transfer resistance was the main factor affecting the absorption rate.
基金National Natural Science Foundation of China(52275328,51875157)。
文摘Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.
基金supported by the National Key Research&Development Program of China(2021YFB3803200)the National Natural Science Foundation of China(22288102).
文摘Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully understood yet,resulting in a lack of theoretical basis for synthesis process improvement.Here,the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory.Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions.Based on theoretical reaction rate ratios,reaction pathways were selected,and a simplified reaction network was derived.It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions.The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data.This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.
