The catalytic diesel particulate filter(CDPF)is the most widely used after-treatment device for controlling diesel engine soot emissions.The development of cost-effective catalysts is crucial for diesel engines to com...The catalytic diesel particulate filter(CDPF)is the most widely used after-treatment device for controlling diesel engine soot emissions.The development of cost-effective catalysts is crucial for diesel engines to comply with future ultra-low emission regulations.This paper studies a new type of Ce/La modified Cs-V non-noble metal CDPF catalyst.Three test catalysts(Cs-V,Cs-V-5%Ce,and Cs-V-5%La)were formulated to explore the physical properties,activity,and sulfur resistance through XRD,SEM,XPS,and TPO tests.And TGA tests with different catalyst-to-soot mass ratios were designed to analyze the reaction kinetics.The results show that the soot oxidation process is divided into three stages:slow oxidation,rapid oxidation,and soot burnout.SEM and XRD results show that,compared with Ce doping,La-doped catalysts have less damage to the microstructure of the first active component,Cs_(2)V_(4)O_(11).XPS results show that the introduction of Ce and La is beneficial to the formation of oxygen vacancies and lattice distortion,increasing the proportion of active oxygen species,thereby improving the soot oxidation activity,among which La-doped active oxygen species have the highest proportion(94%).And the Cs-V-5%La catalyst has the best effect on improving the soot conversion of the three stages.The fresh state has the best low-temperature activity index,the lowest characteristic temperature(T_(50) of 374℃)and activation energy(115.01 kJ/mol),and excellent sulfur resistance.The soot conversion and oxidation speed of the three stages decreases,duration lengthens,and activation energy increases by more than 100 kJ/mol as catalyst-to-soot mass ratios decrease.展开更多
Precise and quantitative measurement of soot particle emission plays an essential role in accurately assessing the combustion performance of aero-engine combustors and infrared signature levels in aircraft exhausts.Am...Precise and quantitative measurement of soot particle emission plays an essential role in accurately assessing the combustion performance of aero-engine combustors and infrared signature levels in aircraft exhausts.Among various intrusive or non-intrusive approaches for soot diagnostics,Laser-Induced Incandescence(LⅡ)technique has been increasingly applied for soot concentration measurement in various combustion environments such as laminar flames and internal combustion engines due to its high spatial resolution and sensitivity.As for LⅡmeasurement in aero-engine combustors,however,it normally suffers from very limited optical accesses and often faces mandatory requirements of oblique imaging from a small backward angle.In this work,we demonstrate a Two-Color(2C)LⅡsystem that simultaneously captures LⅡsignal images at two distinct wavelengths using a Scheimpflug imaging configuration.A projective transformation algorithm and image overlapping procedures were employed to spatially correct the raw Scheimpflug LⅡimages.Performance validation of the developed 2C-Scheimpflug LⅡsystem was first conducted under specified conditions in a laminar C_(2)H_(4)/air McKenna flame.The obtained Soot Volume Fraction(SVF)level and its spatial distribution are in consistent with previous studies under identical flame conditions reported by other research groups.Finally,as a demonstration of engineering benchmark application,we applied the developed 2C-Scheimpflug LⅡsystem to measure SVF distribution in the cross-section plane perpendicular to the direction of flame propagation at the exhaust of a single-sector dual-swirl aero-engine model combustor.Transient soot production events were observed and characteristics of the SVF distribution were investigated.These experimental results suggest the feasibility of the 2C-Scheimpflug LⅡtechnique developed in this work for precise and quantitative measurements of soot concentration in practical environments.展开更多
Gasoline soot particles pose a severe threat to the ecological environment and human health,but they can be potentially filtered out by using catalytic gasoline particulate filter(cGPF),whose core component is a catal...Gasoline soot particles pose a severe threat to the ecological environment and human health,but they can be potentially filtered out by using catalytic gasoline particulate filter(cGPF),whose core component is a catalyst coating.To develop more effective catalyst coatings with excellent activity,stability,and water resistance,a kind of composite oxide MnO_(x)/CeO_(2)-ZrO_(2) was synthesized using different methods,and its soot oxidation performance was evaluated under low O_(2) concentrations.Herein,MnO_(x)/CeO_(2)-ZrO_(2) prepared by impregnation(abbreviated as MCZ-IM)exhibits a T_(50)(temperature required for 50% soot conversion)of 329℃in 1%O_(2) and 370℃ in 0.5%O_(2),displaying better comprehensive performance when compared to catalysts prepared by high-energy ball milling(abbreviated as MCZ-HB)and co-precipitation(abbreviated as MCZ-CP).Structure-activity relationship reveals that soot oxidation under low O_(2) concentrations is weakly correlated with textural and structural properties,but strongly depends on the generation and migration of active oxygen species(AOS),especially superoxide(O_(2)^(-))and peroxide(O_(2)^(2-))anions,which are linked to redox properties,oxygen storage and release capacity,as well as amount of oxygen vacancies.The impregnation method enhances oxygen species adsorption,activation and desorption more effectively,endowing it with a more effective approach to enhancing AOS generation and mobility.Therefore,this study not only provides a preparation strategy for particulate matter oxidation catalysts applicable to actual operating conditions,but also offers insights into the migration of AOS at low O_(2) concentrations.展开更多
The soot emitted during the operation of diesel engine exhaust seriously threatens the human health and environment,so treating diesel engine exhaust is critical.At present,the most effective method for eliminating so...The soot emitted during the operation of diesel engine exhaust seriously threatens the human health and environment,so treating diesel engine exhaust is critical.At present,the most effective method for eliminating soot particles is post-treatment technology.Preparation of economically viable and highly active soot combustion catalysts is a pivotal element of post-treatment technology.In this study,different single-metal oxide catalysts with fibrous structures and alkali metal-modified hollow nanotubular Mn-based oxide catalysts were synthesized using centrifugal spinning method.Activity evaluation results showed that the manganese oxide catalyst has the best catalytic activity among the prepared single-metal oxide catalysts.Further research on alkali metal modification showed that doping alkali metals is beneficial for improving the oxidation state of manganese and generating a large number of reactive oxygen species.Combined with the structural effect brought by the hollow nanotube structure,the alkali metal-modified Mn-based oxide catalysts exhibit superior catalytic performance.Among them,the Cs-modified Mn-based oxide catalyst exhibits the best catalytic performance because of its rich active oxygen species,excellent NO oxidation ability,abundant Mn^(4+)ions(M^(n4)+/Mn^(n+)=64.78%),and good redox ability.The T_(10),T_(50),T_(90),and CO_(2)selectivity of the Cs-modified Mn-based oxide catalyst were 267°C,324°C,360°C,and 97.8%,respectively.展开更多
In the quest to develop high-performance lubrication additives,a novel nanocomposite comprising biodiesel soot modified by silver(Ag/BDS)was synthesized.The tribological behavior of Ag/BDS nanocomposite as an additive...In the quest to develop high-performance lubrication additives,a novel nanocomposite comprising biodiesel soot modified by silver(Ag/BDS)was synthesized.The tribological behavior of Ag/BDS nanocomposite as an additive for liquid paraffin(LP)were systematically investigated using response surface methodology.To elucidate the friction and wear mechanisms associated with the Ag/BDS nanocomposite,various analytical techniques were employed,including scanning electron microscopy with energy-dispersive spectroscopy(SEM/EDS),Raman spectroscopy,and molecular dynamics simulations.The results show that the concentration of Ag/BDS has a significant impact on the tribological properties of LP under different applied loads and sliding speeds.Notably,LP containing 0.25%Ag/BDS shows the most favorable tribological performance and in comparison,to pure LP,the average friction coefficient and average wear volume have been reduced by 42.7%and 21.2%,respectively.The mechanisms underlying the reduction in friction and anti-wear mechanism of Ag/BDS have been attributed to the excellent synergies of Ag and BDS.Specifically,the Ag particles facilitate the incorporation of BDS particles in the formation of uniform boundary lubrication films.展开更多
Effective lattice oxygen(Olatt)activation at low temperatures has long been a challenge in catalytic oxidation reactions.Traditional thermal catalytic soot combustion,even with Pt/Pd catalysts,is inefficient at exhaus...Effective lattice oxygen(Olatt)activation at low temperatures has long been a challenge in catalytic oxidation reactions.Traditional thermal catalytic soot combustion,even with Pt/Pd catalysts,is inefficient at exhaust temperatures below 200℃,particularly under conditions of frequent idling.Herein,we report an effective strategy utilizing non-thermal plasma(NTP)to activate Olatt in Ce_(1–x)Co_(x)O_(2–δ)catalysts,achieving dramatic enhancement of the soot combustion rate at low temperatures.At 200℃ and 4.3 W(discharge power,P_(dis)),NTP-Ce_(0.8)Co_(0.2)O_(2–δ)achieved 96.9%soot conversion(X_(C)),99.0%CO_(2) selectivity(S(CO_(2)))and a maximum energy conversion efficiency(Emax)of 14.7 g kWh^(–1).Compared with previously reported results,NTP-Ce_(0.8)Co_(0.2)O_(2–δ)exhibits the highest S(CO_(2))and Emax values.Remarkably,even without heating,X_(C),Emax,and S(CO_(2))reached 92.1%,6.1 g kWh–1,and 97.5%,respectively,at 6.3 W(P_(dis)).The results of characterization and theoretical calculation demonstrated that Co dopes into the CeO_(2) crystal lattice and forms an asymmetric Ce–O–Co structure,making oxygen“easy come,easy go”,thereby enabling the rapid combustion of soot over NTP-Ce_(0.8)Co_(0.2)O_(2–δ).This study highlights the great potential of NTP for activating Olatt and provides valuable insights into the design of efficient NTP-adapted catalysts for oxidation reactions.展开更多
Oxygenated fuels can reduce harmful emissions without affecting engine performance,meeting the big challenge in the transportation industry,which keeps the environment safe and reduces global warming.This study invest...Oxygenated fuels can reduce harmful emissions without affecting engine performance,meeting the big challenge in the transportation industry,which keeps the environment safe and reduces global warming.This study investigates the impact of biodiesel injection strategies and fuel injection pressures(FIP)on diesel engine exhaust emission characteristics.The engine is fuelled with 20%Jatropha biodiesel(JB)and 80%diesel,named JB20D.The ratios of fuel injection pressures started with injecting the fuel(diesel and JB20D)from 200 bar to 500 bar.The experimental outcomes indicate that the engine performance of brake-specific fuel consumption increased by 21.36%from the burning of JB20D compared with diesel,while brake thermal efficiency improved by 6.54%for low and high FIP compared to the diesel.The high fuel injection pressures slightly decrease the nitrogen oxide(NOX)emissions for both diesel and biodiesel.The emissions of NOX decreased from the combustion of JB20D by 18.7%under high fuel injection pressures compared to diesel.The concentration of soot particulate decreased by 20.4%form JB20D combustion than those combusted from diesel fuel.展开更多
The extensive use of diesel engines has led to significant emissions of pollutants,especially soot particles,which pose serious risks to both the environment and human health.At present,developing catalysts with low–...The extensive use of diesel engines has led to significant emissions of pollutants,especially soot particles,which pose serious risks to both the environment and human health.At present,developing catalysts with low–temperature activity,low cost,and high stability remains the core challenge in eliminating soot from diesel engine exhaust.This paper first reviews the mechanisms of soot catalytic oxidation.Based on these mechanisms,the current design directions for soot catalysts are summarized and discussed.On the one hand,the effects of modification methods such as doping,loading,and solid solution on the performance of manganese-based catalysts are reviewed from the perspective of intrinsic activity.On the other hand,the research progress on manganese-based catalysts with specific morphological structures for soot oxidation is explored.Following the identification of design strategies,the commonly used preparation methods to achieve these designs are also outlined.Finally,the paper highlights the challenges associated with manganese-based catalysts in soot catalysis and discusses future research and development directions.展开更多
Catalytic oxidation of soot is of great importance for emission control on diesel vehicles.In this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-...Catalytic oxidation of soot is of great importance for emission control on diesel vehicles.In this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-temperature calcination greatly improved the activity of the catalyst.When the calcination temperature was increased from 500℃ to 750℃,T_(50) decreased from 456.9℃ to 389.8℃ in a NO/O_(2)/H_(2)O/N_(2) atmosphere.Characterization results revealed that high-temperature calcination can promote the ability to transfer negative charge density from Cs to other metal cations in Cs/Co/Ce-Sn,which will facilitate the production of more oxygen defects and the generation of more surface-active oxygen species.Surfaceactive oxygen species are beneficial to the oxidation of NO to NO_(2),leading to the high yield of NO_(2) exploitation.Therefore,the Cs/Co/Ce-Sn catalyst calcined at 750℃ demonstrated higher activity than that calcined at 500℃.This work provides a pathway to prepare high efficiency catalysts for the removal of soot and significant insight into the effects of calcination on soot oxidation catalysts.展开更多
Catalyzed gasoline particulate filters(cGPFs)are being developed to enable compliance with the particulate number limits for passenger cars equipped with gasoline direct injection(GDI)engines in China and Europe,It is...Catalyzed gasoline particulate filters(cGPFs)are being developed to enable compliance with the particulate number limits for passenger cars equipped with gasoline direct injection(GDI)engines in China and Europe,It is appealing to build catalysts with ceria—an irreplaceable"reducible"component in three-way converters—to help eliminate the soot particles trapped in cGPFs via O_(2)-assisted combustion.While research aiming at understanding how these recipes function has continued for more than two decades,a universal model elucidating the roles of different"active oxygen"species is yet to be realized.In this perspective,by critically assessing the reported data about gasoline soot catalytic combustion over ceria catalysts,it is suggested that ceria ignites soot through contributing its lattice oxygen,giving rise to a"hot ring"region at the periphery of soot-catalyst interface.During the"re-oxidation"semi-cycles,electrophilic superoxides and/or peroxides(O_(x)^(n-))are produced at the Ce^(3+)and oxygen vacancy sites enriched in this collar-like region,and then work as key reactive phases for soot deep oxidation.Based on this"O_(x)^(n-)assisted"Mars-van Krevelen mechanism,several guidelines for ceria catalyst designing are proposed,ending with a summary about where future opportunities and challenges may lie in developing efficient and practical cGPF catalysts.展开更多
Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel,and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems.H...Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel,and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems.However,soot as a functional material is also widely used in energy storage and superhydrophobic materials.As a partial oxidation technology,the entrained flow coal gasification process will produce part of the soot.It is important to separate soot from the coal gasification fine slag(CGFS)and understand its structural characteristics for soot utilization.For this purpose,two industrial typical pulverized coal gasification fine slag(PCGFS)and coal-water slurry gasification fine slag(WCGFS)were selected for this study.The results showed that both fine slags were rich in soot,and the dry ash free mass fraction of soot in PCGFS and WCGFS was 6.24%and 2.91%,respectively,and the soot of PCGFS had a hollow carbon nanosphere morphology,while the soot of WCGFS showed a flocculent irregular morphology.The average fringe length,fringe tortuosity,and fringe spacing of the soot were 0.84 nm,1.21,and 0.45 nm,respectively.Compared to the WCGFS,the soot particles of PCGFS have less continuity of molecular bonds within the lattice,the larger the defects within the lattice,the fewer isolated lattice carbon layers there are.This study provides important theoretical support for understanding the structural characteristics and next applications of soot in the entrained flow coal gasification fine slag.展开更多
The spatiotemporal distribution of soot concentration in aero-engine combustor is important for assessing its combustion performance.Here,we report experimental measurements of soot concentration in terms of Soot Volu...The spatiotemporal distribution of soot concentration in aero-engine combustor is important for assessing its combustion performance.Here,we report experimental measurements of soot concentration in terms of Soot Volume Fraction(SVF)and its spatiotemporal distribution in a single-sector dual-swirl aero-engine combustor using Two-Color Laser-Induced Incandescence(2C-LII).It is shown that soot predominantly forms in the symmetrical vortices of the primary combustion zone,exhibiting a V-type distribution with higher concentration in the lower half of the zone than the upper half,with a small amount distributed in the secondary recirculation zone.Soot emissions at the combustor outlet are relatively low under three typical operating conditions by LII experiments,which is aligned with Smoke Number(SN)from gas analysis.The effect of inlet air temperature on SVF distribution and dynamics in the primary combustion zone is studied,which suggests that the SVF level in the primary combustion zone monotonically increases with the temperature.Meanwhile,the SVF distribution becomes more symmetrical as the inlet temperature increases,although the overall SVF level in the lower half of the zone is still higher.We also investigate the influence of the inlet air pressure on the SVF distribution at the combustor outlet.The soot concentration at the combustor outlet increases with inlet pressure,mainly distributed irregularly across both sides and the center.On both sides,the distribution is continuous,while the center exhibits dot-like and linear patterns.Numerical simulations correlated SVF distribution with the flow field in the primary combustion zone,qualitatively explaining the observed SVF distribution behavior.These results under various conditions can provide valuable insights for improving the performance of this specific combustor and designing high-temperature-rise combustors in the future.展开更多
Quantitative measurement of Soot Volume Fraction (SVF) is an essential prerequisite for controlling soot particle emissions from aero-engine combustors. As an in-situ and non-intrusive optical diagnostic technique, La...Quantitative measurement of Soot Volume Fraction (SVF) is an essential prerequisite for controlling soot particle emissions from aero-engine combustors. As an in-situ and non-intrusive optical diagnostic technique, Laser-Induced Incandescence (LII) has been increasingly applied for soot concentration quantification in various combustion environments such as laminar flame, vehicle exhaust, internal combustion chamber as well as aero-engine combustor. In this work, we experimentally measured the spatial and temporal distribution of SVF using two-color LII technique at the outlet of a single-sector dual-swirl aero-engine model combustor. The effect of inlet pressure and air preheat temperature on the SVF distribution was separately investigated within a pressure range of 241–425 kPa and a temperature range of 292–500 K. The results show that soot production increases with the inlet pressure but generally decreases with the air preheat temperature. Qualitative analysis was provided to explain the above results of parametric studies. The LII experiments were also conducted under 3 designed conditions to evaluate soot emission under practical operations. Particularly, weak soot emission was detected at the outlet under the idle condition. Our experimental results provide a valuable benchmark for evaluating soot emission in the exhaust plume of this aero-engine combustor during practical operations.展开更多
The composite oxides xAg/Co_（0.93）Ce_（0.07）（x=Ag/（Co＋Ce） molar ratio）,intended for use as high performance catalytic materials,were successfully prepared via citric acid complexation.The effects of silver on ...The composite oxides xAg/Co_（0.93）Ce_（0.07）（x=Ag/（Co＋Ce） molar ratio）,intended for use as high performance catalytic materials,were successfully prepared via citric acid complexation.The effects of silver on the performance of these substances during soot combustion were subsequently investigated.Under O_2,the 0.3Ag/Co_（0.93）Ce_（0.07） catalyst resulted in the lowest ignition temperature,T_（10）,of197 ℃,while the minimum light-off temperature was obtained from both 0.2Ag/Co_（0.93）Ce_（0.07） and0.3Ag/Co_（0.93）Ce_（0.07） in the NO_x atmosphere.These materials were also characterized by various techniques,including H_2,soot and NO_x temperature programmed reduction,X-ray diffraction,and electron paramagnetic resonance,Raman,X-ray photoelectron,and Fourier transform infrared spectroscopic analyses.The results demonstrated that silver significantly alters the catalytic behavior under both O_2 and NO_x,even though the lattice structure of the mixed oxide is not affected.Surface silver oxides generated under the O_2 atmosphere favor soot combustion by participating in the redox cycles between soot and the silver oxide,whereas the AgNO_3 that forms in a NO_x-rich atmosphere facilitates soot abatement at a lower temperature.The inferior activity of AgNO_3 relative to that of Ag_2O results in the different catalytic performance in the presence of NO_x or O_2.展开更多
Soot,a product of insufficient combustion,is usually in the form of aggregate. The multi-scattering of soot fractal aggregates has been proved to play an important role in studying the soot radiative properties,which ...Soot,a product of insufficient combustion,is usually in the form of aggregate. The multi-scattering of soot fractal aggregates has been proved to play an important role in studying the soot radiative properties,which is rarely considered in predicting the radiative heat transfer in combustion flame. In the present study,based on the weighted sum of gray soot fractal aggregate(WSGSA) model,which is used to predict the temperature field and soot aggregates in turbulent diffusion flame,the flame temperature distribution and soot volume fraction distribution under the conditions of the model without considering radiation,the default radiation model in Fluent software and the WSGSA model are calculated respectively. The results show that the flame temperature will be seriously overestimated without considering radiation and the maximum relative discrepancy of flame centerline temperature is about 64.5%. The accuracy will be improved by the default radiation model in the Fluent software,but the flame temperature is still overestimated and the maximum relative discrepancy of flame centerline temperature is about 42.1%. However,more satisfactory results can be obtained by the WSGSA model,and the maximum relative discrepancy of flame centerline temperature is no more than 15.3%. Similar conclusions can also be obtained in studying the temperature distribution along different flame heights. Moreover,the soot volume fraction can be predicted more accurately with the application of the WSGSA model. Both without considering radiation and using the default radiation model in the Fluent software will result in the underestimating of soot volume fraction. All the results reveal that the WSGSA model can be used to predict the temperature and soot aggregates in the CH/air turbulent diffusion flame.展开更多
基金supported by the National Natural Science Foundation of China(No.52206167)the Science and Technology Talents and Platform Program(Academician ExpertWorkstation)(No.202305AF150109)+1 种基金Shanghai Sailing Program(No.21YF1448900)the Introduced and co-builded high-level research and development institutions of Jiangxi Province(No.20212CCH45004).
文摘The catalytic diesel particulate filter(CDPF)is the most widely used after-treatment device for controlling diesel engine soot emissions.The development of cost-effective catalysts is crucial for diesel engines to comply with future ultra-low emission regulations.This paper studies a new type of Ce/La modified Cs-V non-noble metal CDPF catalyst.Three test catalysts(Cs-V,Cs-V-5%Ce,and Cs-V-5%La)were formulated to explore the physical properties,activity,and sulfur resistance through XRD,SEM,XPS,and TPO tests.And TGA tests with different catalyst-to-soot mass ratios were designed to analyze the reaction kinetics.The results show that the soot oxidation process is divided into three stages:slow oxidation,rapid oxidation,and soot burnout.SEM and XRD results show that,compared with Ce doping,La-doped catalysts have less damage to the microstructure of the first active component,Cs_(2)V_(4)O_(11).XPS results show that the introduction of Ce and La is beneficial to the formation of oxygen vacancies and lattice distortion,increasing the proportion of active oxygen species,thereby improving the soot oxidation activity,among which La-doped active oxygen species have the highest proportion(94%).And the Cs-V-5%La catalyst has the best effect on improving the soot conversion of the three stages.The fresh state has the best low-temperature activity index,the lowest characteristic temperature(T_(50) of 374℃)and activation energy(115.01 kJ/mol),and excellent sulfur resistance.The soot conversion and oxidation speed of the three stages decreases,duration lengthens,and activation energy increases by more than 100 kJ/mol as catalyst-to-soot mass ratios decrease.
基金supported by the Equipment Test and Evaluation Technology Research Project,China(No.2100070017)the Natural Science Foundation of Gansu Province,China(No.24JRRA415)。
文摘Precise and quantitative measurement of soot particle emission plays an essential role in accurately assessing the combustion performance of aero-engine combustors and infrared signature levels in aircraft exhausts.Among various intrusive or non-intrusive approaches for soot diagnostics,Laser-Induced Incandescence(LⅡ)technique has been increasingly applied for soot concentration measurement in various combustion environments such as laminar flames and internal combustion engines due to its high spatial resolution and sensitivity.As for LⅡmeasurement in aero-engine combustors,however,it normally suffers from very limited optical accesses and often faces mandatory requirements of oblique imaging from a small backward angle.In this work,we demonstrate a Two-Color(2C)LⅡsystem that simultaneously captures LⅡsignal images at two distinct wavelengths using a Scheimpflug imaging configuration.A projective transformation algorithm and image overlapping procedures were employed to spatially correct the raw Scheimpflug LⅡimages.Performance validation of the developed 2C-Scheimpflug LⅡsystem was first conducted under specified conditions in a laminar C_(2)H_(4)/air McKenna flame.The obtained Soot Volume Fraction(SVF)level and its spatial distribution are in consistent with previous studies under identical flame conditions reported by other research groups.Finally,as a demonstration of engineering benchmark application,we applied the developed 2C-Scheimpflug LⅡsystem to measure SVF distribution in the cross-section plane perpendicular to the direction of flame propagation at the exhaust of a single-sector dual-swirl aero-engine model combustor.Transient soot production events were observed and characteristics of the SVF distribution were investigated.These experimental results suggest the feasibility of the 2C-Scheimpflug LⅡtechnique developed in this work for precise and quantitative measurements of soot concentration in practical environments.
基金Advanced Materials-National Science and Technology Major Project(2024ZD0606500)National Natural Science Foundation of China(21902110)Sichuan Provincial Science Foundation(2023NSFSC0093)。
文摘Gasoline soot particles pose a severe threat to the ecological environment and human health,but they can be potentially filtered out by using catalytic gasoline particulate filter(cGPF),whose core component is a catalyst coating.To develop more effective catalyst coatings with excellent activity,stability,and water resistance,a kind of composite oxide MnO_(x)/CeO_(2)-ZrO_(2) was synthesized using different methods,and its soot oxidation performance was evaluated under low O_(2) concentrations.Herein,MnO_(x)/CeO_(2)-ZrO_(2) prepared by impregnation(abbreviated as MCZ-IM)exhibits a T_(50)(temperature required for 50% soot conversion)of 329℃in 1%O_(2) and 370℃ in 0.5%O_(2),displaying better comprehensive performance when compared to catalysts prepared by high-energy ball milling(abbreviated as MCZ-HB)and co-precipitation(abbreviated as MCZ-CP).Structure-activity relationship reveals that soot oxidation under low O_(2) concentrations is weakly correlated with textural and structural properties,but strongly depends on the generation and migration of active oxygen species(AOS),especially superoxide(O_(2)^(-))and peroxide(O_(2)^(2-))anions,which are linked to redox properties,oxygen storage and release capacity,as well as amount of oxygen vacancies.The impregnation method enhances oxygen species adsorption,activation and desorption more effectively,endowing it with a more effective approach to enhancing AOS generation and mobility.Therefore,this study not only provides a preparation strategy for particulate matter oxidation catalysts applicable to actual operating conditions,but also offers insights into the migration of AOS at low O_(2) concentrations.
基金supported by National Key R&D Program of China(2022YFB3506200,2022YFB3504100)National Natural Science Foundation of China(22072095,22372107,22202058)+3 种基金Excellent Youth Science Foundation of Liaoning Province(2022-YQ-20)Shenyang Science and Technology Planning Project(22-322-3-28)Liaoning Xingliao talented youth Top talent program(XLYC2203007)University Joint Education Project for China-Central and Eastern European Countries(2021097).
文摘The soot emitted during the operation of diesel engine exhaust seriously threatens the human health and environment,so treating diesel engine exhaust is critical.At present,the most effective method for eliminating soot particles is post-treatment technology.Preparation of economically viable and highly active soot combustion catalysts is a pivotal element of post-treatment technology.In this study,different single-metal oxide catalysts with fibrous structures and alkali metal-modified hollow nanotubular Mn-based oxide catalysts were synthesized using centrifugal spinning method.Activity evaluation results showed that the manganese oxide catalyst has the best catalytic activity among the prepared single-metal oxide catalysts.Further research on alkali metal modification showed that doping alkali metals is beneficial for improving the oxidation state of manganese and generating a large number of reactive oxygen species.Combined with the structural effect brought by the hollow nanotube structure,the alkali metal-modified Mn-based oxide catalysts exhibit superior catalytic performance.Among them,the Cs-modified Mn-based oxide catalyst exhibits the best catalytic performance because of its rich active oxygen species,excellent NO oxidation ability,abundant Mn^(4+)ions(M^(n4)+/Mn^(n+)=64.78%),and good redox ability.The T_(10),T_(50),T_(90),and CO_(2)selectivity of the Cs-modified Mn-based oxide catalyst were 267°C,324°C,360°C,and 97.8%,respectively.
基金funded by the National Natural Science Foundation of China(52075141)the Open Project of Anhui Province Key Laboratory of Critical Friction Pair for Advanced Equipment(LCFP-2408)+9 种基金Key Research&Development(R&D)Plan of Anhui Province under Grant(2022a05020019)Support Program for Outstanding Young Talents in Anhui Province Colleges and Universities(gxyq2022079)Excellent Research and Innovation Teams Project of Anhui Province's Universities(2022AH010092)Discipline Construction Quality Improvement Project of Chaohu University(kj22fdzy03,XLZ202307,XLZ202301)School-level Scientific Research Project of Chaohu University(XLY-202112)Scientific Research Planning Project of Anhui Provincial(2022AH051726)Anhui Province University Science and Engineering Teachers'Internship Program in Enterprises(2024jsqygz89)Anhui Province College Students'Innovation and Entrepreneurship Training Program(S202410380020)Anhui Province Postdoctoral Research Project(2024A773)Horizontal Research Project of Chaohu University(hxkt20230006).
文摘In the quest to develop high-performance lubrication additives,a novel nanocomposite comprising biodiesel soot modified by silver(Ag/BDS)was synthesized.The tribological behavior of Ag/BDS nanocomposite as an additive for liquid paraffin(LP)were systematically investigated using response surface methodology.To elucidate the friction and wear mechanisms associated with the Ag/BDS nanocomposite,various analytical techniques were employed,including scanning electron microscopy with energy-dispersive spectroscopy(SEM/EDS),Raman spectroscopy,and molecular dynamics simulations.The results show that the concentration of Ag/BDS has a significant impact on the tribological properties of LP under different applied loads and sliding speeds.Notably,LP containing 0.25%Ag/BDS shows the most favorable tribological performance and in comparison,to pure LP,the average friction coefficient and average wear volume have been reduced by 42.7%and 21.2%,respectively.The mechanisms underlying the reduction in friction and anti-wear mechanism of Ag/BDS have been attributed to the excellent synergies of Ag and BDS.Specifically,the Ag particles facilitate the incorporation of BDS particles in the formation of uniform boundary lubrication films.
文摘Effective lattice oxygen(Olatt)activation at low temperatures has long been a challenge in catalytic oxidation reactions.Traditional thermal catalytic soot combustion,even with Pt/Pd catalysts,is inefficient at exhaust temperatures below 200℃,particularly under conditions of frequent idling.Herein,we report an effective strategy utilizing non-thermal plasma(NTP)to activate Olatt in Ce_(1–x)Co_(x)O_(2–δ)catalysts,achieving dramatic enhancement of the soot combustion rate at low temperatures.At 200℃ and 4.3 W(discharge power,P_(dis)),NTP-Ce_(0.8)Co_(0.2)O_(2–δ)achieved 96.9%soot conversion(X_(C)),99.0%CO_(2) selectivity(S(CO_(2)))and a maximum energy conversion efficiency(Emax)of 14.7 g kWh^(–1).Compared with previously reported results,NTP-Ce_(0.8)Co_(0.2)O_(2–δ)exhibits the highest S(CO_(2))and Emax values.Remarkably,even without heating,X_(C),Emax,and S(CO_(2))reached 92.1%,6.1 g kWh–1,and 97.5%,respectively,at 6.3 W(P_(dis)).The results of characterization and theoretical calculation demonstrated that Co dopes into the CeO_(2) crystal lattice and forms an asymmetric Ce–O–Co structure,making oxygen“easy come,easy go”,thereby enabling the rapid combustion of soot over NTP-Ce_(0.8)Co_(0.2)O_(2–δ).This study highlights the great potential of NTP for activating Olatt and provides valuable insights into the design of efficient NTP-adapted catalysts for oxidation reactions.
文摘Oxygenated fuels can reduce harmful emissions without affecting engine performance,meeting the big challenge in the transportation industry,which keeps the environment safe and reduces global warming.This study investigates the impact of biodiesel injection strategies and fuel injection pressures(FIP)on diesel engine exhaust emission characteristics.The engine is fuelled with 20%Jatropha biodiesel(JB)and 80%diesel,named JB20D.The ratios of fuel injection pressures started with injecting the fuel(diesel and JB20D)from 200 bar to 500 bar.The experimental outcomes indicate that the engine performance of brake-specific fuel consumption increased by 21.36%from the burning of JB20D compared with diesel,while brake thermal efficiency improved by 6.54%for low and high FIP compared to the diesel.The high fuel injection pressures slightly decrease the nitrogen oxide(NOX)emissions for both diesel and biodiesel.The emissions of NOX decreased from the combustion of JB20D by 18.7%under high fuel injection pressures compared to diesel.The concentration of soot particulate decreased by 20.4%form JB20D combustion than those combusted from diesel fuel.
基金sponsored by the National Natural Science Foundation of China(Grant 22406050)the Top-Notch Personnel Fund of Henan Agricultural University(Grant 30501029)+2 种基金the Natural Science Foundation of Henan Province(Grant 232300420293)the Science and Technology Project of China Tobacco Shaanxi Industrial Co.,Ltd.(Grant BA000-ZB24010)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(Grant YJS2024JD17).
文摘The extensive use of diesel engines has led to significant emissions of pollutants,especially soot particles,which pose serious risks to both the environment and human health.At present,developing catalysts with low–temperature activity,low cost,and high stability remains the core challenge in eliminating soot from diesel engine exhaust.This paper first reviews the mechanisms of soot catalytic oxidation.Based on these mechanisms,the current design directions for soot catalysts are summarized and discussed.On the one hand,the effects of modification methods such as doping,loading,and solid solution on the performance of manganese-based catalysts are reviewed from the perspective of intrinsic activity.On the other hand,the research progress on manganese-based catalysts with specific morphological structures for soot oxidation is explored.Following the identification of design strategies,the commonly used preparation methods to achieve these designs are also outlined.Finally,the paper highlights the challenges associated with manganese-based catalysts in soot catalysis and discusses future research and development directions.
基金supported by the National Natural Science Foundation of China(Nos.22206183,52225004)the National Key R&D Program of China(No.2022YFC3701804)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23010201)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2022309)。
文摘Catalytic oxidation of soot is of great importance for emission control on diesel vehicles.In this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-temperature calcination greatly improved the activity of the catalyst.When the calcination temperature was increased from 500℃ to 750℃,T_(50) decreased from 456.9℃ to 389.8℃ in a NO/O_(2)/H_(2)O/N_(2) atmosphere.Characterization results revealed that high-temperature calcination can promote the ability to transfer negative charge density from Cs to other metal cations in Cs/Co/Ce-Sn,which will facilitate the production of more oxygen defects and the generation of more surface-active oxygen species.Surfaceactive oxygen species are beneficial to the oxidation of NO to NO_(2),leading to the high yield of NO_(2) exploitation.Therefore,the Cs/Co/Ce-Sn catalyst calcined at 750℃ demonstrated higher activity than that calcined at 500℃.This work provides a pathway to prepare high efficiency catalysts for the removal of soot and significant insight into the effects of calcination on soot oxidation catalysts.
基金supported by the National Natural Science Foundation of China(22076176,22276106)the Natural Science Foundation of Shandong Province(ZR2021YQ14)+3 种基金the Innovation Ability Improvement Project for Technology-based Small-and Medium-sized Enterprises of Shandong Province(2022TSGC1345)Jiangsu Province Science and Technology Plan Special Fund(BZ2022053)Key Research and Development Program of Anhui Province(202104g01020006)the Fundamental Research Funds for the Central Universities(202141008)。
文摘Catalyzed gasoline particulate filters(cGPFs)are being developed to enable compliance with the particulate number limits for passenger cars equipped with gasoline direct injection(GDI)engines in China and Europe,It is appealing to build catalysts with ceria—an irreplaceable"reducible"component in three-way converters—to help eliminate the soot particles trapped in cGPFs via O_(2)-assisted combustion.While research aiming at understanding how these recipes function has continued for more than two decades,a universal model elucidating the roles of different"active oxygen"species is yet to be realized.In this perspective,by critically assessing the reported data about gasoline soot catalytic combustion over ceria catalysts,it is suggested that ceria ignites soot through contributing its lattice oxygen,giving rise to a"hot ring"region at the periphery of soot-catalyst interface.During the"re-oxidation"semi-cycles,electrophilic superoxides and/or peroxides(O_(x)^(n-))are produced at the Ce^(3+)and oxygen vacancy sites enriched in this collar-like region,and then work as key reactive phases for soot deep oxidation.Based on this"O_(x)^(n-)assisted"Mars-van Krevelen mechanism,several guidelines for ceria catalyst designing are proposed,ending with a summary about where future opportunities and challenges may lie in developing efficient and practical cGPF catalysts.
基金supported by the National Natural Science Foundation of China(22168032,21968024)the National Key Research and Development Program of China(2023YFC3904302).
文摘Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel,and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems.However,soot as a functional material is also widely used in energy storage and superhydrophobic materials.As a partial oxidation technology,the entrained flow coal gasification process will produce part of the soot.It is important to separate soot from the coal gasification fine slag(CGFS)and understand its structural characteristics for soot utilization.For this purpose,two industrial typical pulverized coal gasification fine slag(PCGFS)and coal-water slurry gasification fine slag(WCGFS)were selected for this study.The results showed that both fine slags were rich in soot,and the dry ash free mass fraction of soot in PCGFS and WCGFS was 6.24%and 2.91%,respectively,and the soot of PCGFS had a hollow carbon nanosphere morphology,while the soot of WCGFS showed a flocculent irregular morphology.The average fringe length,fringe tortuosity,and fringe spacing of the soot were 0.84 nm,1.21,and 0.45 nm,respectively.Compared to the WCGFS,the soot particles of PCGFS have less continuity of molecular bonds within the lattice,the larger the defects within the lattice,the fewer isolated lattice carbon layers there are.This study provides important theoretical support for understanding the structural characteristics and next applications of soot in the entrained flow coal gasification fine slag.
基金support of the National Science and Technology Major Project of China(No.J2019-V-0005-0096)the National Key Research and Development Program of China(No.2020YFA0405700).
文摘The spatiotemporal distribution of soot concentration in aero-engine combustor is important for assessing its combustion performance.Here,we report experimental measurements of soot concentration in terms of Soot Volume Fraction(SVF)and its spatiotemporal distribution in a single-sector dual-swirl aero-engine combustor using Two-Color Laser-Induced Incandescence(2C-LII).It is shown that soot predominantly forms in the symmetrical vortices of the primary combustion zone,exhibiting a V-type distribution with higher concentration in the lower half of the zone than the upper half,with a small amount distributed in the secondary recirculation zone.Soot emissions at the combustor outlet are relatively low under three typical operating conditions by LII experiments,which is aligned with Smoke Number(SN)from gas analysis.The effect of inlet air temperature on SVF distribution and dynamics in the primary combustion zone is studied,which suggests that the SVF level in the primary combustion zone monotonically increases with the temperature.Meanwhile,the SVF distribution becomes more symmetrical as the inlet temperature increases,although the overall SVF level in the lower half of the zone is still higher.We also investigate the influence of the inlet air pressure on the SVF distribution at the combustor outlet.The soot concentration at the combustor outlet increases with inlet pressure,mainly distributed irregularly across both sides and the center.On both sides,the distribution is continuous,while the center exhibits dot-like and linear patterns.Numerical simulations correlated SVF distribution with the flow field in the primary combustion zone,qualitatively explaining the observed SVF distribution behavior.These results under various conditions can provide valuable insights for improving the performance of this specific combustor and designing high-temperature-rise combustors in the future.
基金supported by the National Key Research and Development Program of China(No.2020YFA0405700).
文摘Quantitative measurement of Soot Volume Fraction (SVF) is an essential prerequisite for controlling soot particle emissions from aero-engine combustors. As an in-situ and non-intrusive optical diagnostic technique, Laser-Induced Incandescence (LII) has been increasingly applied for soot concentration quantification in various combustion environments such as laminar flame, vehicle exhaust, internal combustion chamber as well as aero-engine combustor. In this work, we experimentally measured the spatial and temporal distribution of SVF using two-color LII technique at the outlet of a single-sector dual-swirl aero-engine model combustor. The effect of inlet pressure and air preheat temperature on the SVF distribution was separately investigated within a pressure range of 241–425 kPa and a temperature range of 292–500 K. The results show that soot production increases with the inlet pressure but generally decreases with the air preheat temperature. Qualitative analysis was provided to explain the above results of parametric studies. The LII experiments were also conducted under 3 designed conditions to evaluate soot emission under practical operations. Particularly, weak soot emission was detected at the outlet under the idle condition. Our experimental results provide a valuable benchmark for evaluating soot emission in the exhaust plume of this aero-engine combustor during practical operations.
基金supported by the National Natural Science Foundation of China(21577088)~~
文摘The composite oxides xAg/Co_（0.93）Ce_（0.07）（x=Ag/（Co＋Ce） molar ratio）,intended for use as high performance catalytic materials,were successfully prepared via citric acid complexation.The effects of silver on the performance of these substances during soot combustion were subsequently investigated.Under O_2,the 0.3Ag/Co_（0.93）Ce_（0.07） catalyst resulted in the lowest ignition temperature,T_（10）,of197 ℃,while the minimum light-off temperature was obtained from both 0.2Ag/Co_（0.93）Ce_（0.07） and0.3Ag/Co_（0.93）Ce_（0.07） in the NO_x atmosphere.These materials were also characterized by various techniques,including H_2,soot and NO_x temperature programmed reduction,X-ray diffraction,and electron paramagnetic resonance,Raman,X-ray photoelectron,and Fourier transform infrared spectroscopic analyses.The results demonstrated that silver significantly alters the catalytic behavior under both O_2 and NO_x,even though the lattice structure of the mixed oxide is not affected.Surface silver oxides generated under the O_2 atmosphere favor soot combustion by participating in the redox cycles between soot and the silver oxide,whereas the AgNO_3 that forms in a NO_x-rich atmosphere facilitates soot abatement at a lower temperature.The inferior activity of AgNO_3 relative to that of Ag_2O results in the different catalytic performance in the presence of NO_x or O_2.
基金supported by the National Natural Science Foundation of China (No. 51806103)the Aeronautical Science Foundation of China (No.201928052002)the Fundamental Research Funds for the Central Universities(No.NT2021007)。
文摘Soot,a product of insufficient combustion,is usually in the form of aggregate. The multi-scattering of soot fractal aggregates has been proved to play an important role in studying the soot radiative properties,which is rarely considered in predicting the radiative heat transfer in combustion flame. In the present study,based on the weighted sum of gray soot fractal aggregate(WSGSA) model,which is used to predict the temperature field and soot aggregates in turbulent diffusion flame,the flame temperature distribution and soot volume fraction distribution under the conditions of the model without considering radiation,the default radiation model in Fluent software and the WSGSA model are calculated respectively. The results show that the flame temperature will be seriously overestimated without considering radiation and the maximum relative discrepancy of flame centerline temperature is about 64.5%. The accuracy will be improved by the default radiation model in the Fluent software,but the flame temperature is still overestimated and the maximum relative discrepancy of flame centerline temperature is about 42.1%. However,more satisfactory results can be obtained by the WSGSA model,and the maximum relative discrepancy of flame centerline temperature is no more than 15.3%. Similar conclusions can also be obtained in studying the temperature distribution along different flame heights. Moreover,the soot volume fraction can be predicted more accurately with the application of the WSGSA model. Both without considering radiation and using the default radiation model in the Fluent software will result in the underestimating of soot volume fraction. All the results reveal that the WSGSA model can be used to predict the temperature and soot aggregates in the CH/air turbulent diffusion flame.
