Defect engineering in metal organic frameworks(MOFs)has captured significant attention in the field of photocatalysis.A series of UiO-66(Ce)(UiO=University of Oslo)MOFs with different contents of missing-linker defect...Defect engineering in metal organic frameworks(MOFs)has captured significant attention in the field of photocatalysis.A series of UiO-66(Ce)(UiO=University of Oslo)MOFs with different contents of missing-linker defects have been developed for the photocatalytic selective oxidation of benzylamine(BA)and thioanisole(TA)under visible light.The introduction of missing-linker defects promotes the formation of unsaturated Ce sites with a high Ce3+content.It also generates a high concentration of oxygen vacancies.In situ Fourier transform infrared spectroscopy(FTIR)results revealed that BA and TA molecules were activated on coordinatively unsaturated Ce sites via the H-N…Ce and the C-S…Ce interactions,respectively.Simulated in situ electron paramagnetic resonance(EPR)data indicate that O_(2) activation and reduction occur at coordinatively unsaturated Ce^(3+)sites to form·O_(2)^(-).This is accelerated by the Ce^(3+)/Ce^(4+)redox cycle associated with the photogenerated electrons.The corresponding photogenerated holes are involved in the deprotonation of the activated BA and TA.The most active sample exhibits 98.4%and 95.5%conversion rates for BA and TA oxidation.Mechanisms for the molecular activation are proposed at the molecular level.展开更多
The rational fabrication of photocatalysts with dual functions upon visible light, such as photocatalytic radioactive U(Ⅵ)reduction and value-added organic oxidation, is highly desirable but remains huge challenge. H...The rational fabrication of photocatalysts with dual functions upon visible light, such as photocatalytic radioactive U(Ⅵ)reduction and value-added organic oxidation, is highly desirable but remains huge challenge. Here, we couple the photocatalytic U(Ⅵ) reduction with the oxidative organic synthesis to one system using novel extended π-conjugated framework(Cu@ThTCPP) without the expense of sacrificial reagents. Noticeably, the as-prepared Cu@Th-TCPP linked by tetratopic tetrakis(4-carboxyphenyl)porphyrin(TCPP) ligand and unique Th(μ-O)(HCOO)(HO)secondary building unit(SBU) exhibits significantly enhanced activity when the photocatalytic U(Ⅵ) reduction and thioanisole oxidation were integrated to one system.Further experimental characterizations demonstrate that the highly conjugated framework of Cu@Th-TCPP is good for the charge transfer and separation, while incorporating Cusite further accelerates the charge-carrier dynamics, thus giving rise to the dual-functional property. Apparently, this strategy conforms to atomic economy, opens a new horizon to address radioactive environmental pollution in natural water systems and soils, and simultaneously produces valuable chemicals.展开更多
Secondary organic aerosol （SOA） formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodyn...Secondary organic aerosol （SOA） formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer （ALTOFMS）, respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 μm （i.e., PM2.5）, and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.展开更多
A simple and effective method of removing polluted organics in water is reported here.Titanium dioxide is a catalyst in photo-oxidation of monocrotophos.The mechanism of photocatalytic oxidation and the kinetics of th...A simple and effective method of removing polluted organics in water is reported here.Titanium dioxide is a catalyst in photo-oxidation of monocrotophos.The mechanism of photocatalytic oxidation and the kinetics of the reaction were studied. This same principle also leads to the construction of instrument of PTR-FIA analysis for monitoring organic phosphorus and phosphate in water.展开更多
Investigating the impacts of soil conversion on soil organic carbon(OC) content and its fractions within soil aggregates is essential for defining better strategies to improve soil structure and OC sequestration in te...Investigating the impacts of soil conversion on soil organic carbon(OC) content and its fractions within soil aggregates is essential for defining better strategies to improve soil structure and OC sequestration in terrestrial ecosystems. However, the consequences of soil conversion from paddy soil to upland soil for soil aggregates and intra-aggregate OC pools are poorly understood. Therefore, the objective of this study was to quantify the effects of soil conversion on soil aggregate and intra-aggregate OC pool distributions. Four typical rice-producing areas were chosen in North and South China, paired soil samples(upland soil converted from paddy soil more than ten years ago vs. adjacent paddy soil) were collected(0–20 cm) with three replicates in each area. A set of core parameters(OC preservation capacity, aggregate carbon(C) turnover, and biological activity index) were evaluated to assess the responses of intra-aggregate OC turnover to soil conversion. Results showed that soil conversion from paddy soil to upland soil significantly improved the formation of macro-aggregates and increased aggregate stability. It also notably decreased soil intra-aggregate OC pools, including easily oxidized OCa(EOCa), particulate OCa(POCa), and mineral-bound(MOCa) OC, and the sensitivity of aggregate-associated OC pools to soil conversion followed the order: EOCa(average reduction of 21.1%) > MOCa(average reduction of 15.4%) > POCa(average reduction of 14.8%). The potentially mineralizable C(C_(0)) was significantly higher in upland soil than in paddy soil, but the corresponding decay constant(k) was lower in upland soil than in paddy soil. Random forest model and partial correlation analysis showed that EOCa and pH were the important nutrient and physicochemical factors impacting k of C mineralization in paddy soil,while MOCa and C-related enzyme(β-D-cellobiohydrolase) were identified as the key factors in upland soil. In conclusion, this study evidenced that soil conversion from paddy soil to upland soil increased the percentage of macro-aggregates and aggregate stability, while decreased soil aggregate-associated C stock and k of soil C mineralization on a scale of ten years. Our findings provided some new insights into the alterations of soil aggregates and potential C sequestration under soil conversion system in rice-producing areas.展开更多
Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)a...Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)as precursors,are extensively used as catalysts for VOCs oxidation due to their uniformity advantage.This review summarizes the developments in the LDH-derived VOCs heterogeneous catalytic oxidation over the last 10 years.Particularly,it addresses the VOCs abatement performance over MMO,noble metal/MMO,core-shell structured MMO,and integral MMO film catalysts originating from LDHs.Moreover,it highlights the water vapor effect and oxidation mechanism.This review indicates that LDH-based catalysts are a category of important VOCs oxidation materials.展开更多
Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the s...Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the sources and causes of LOC contamination are. In this study, soil organic carbon（SOC）, total nitrogen（TN）, microbial biomass carbon（MBC）, microbial biomass nitrogen（MBN） and LOC were analyzed based on different soil horizons and elevations using turnover time in an experimental site（3700 m to 4300 m area） in Sygera. SOC and LOC in higher-elevation vegetation types were higher than that of in lower-elevation vegetation types. Our results presented that the soil microbial biomass carbon（SMBC） and soil microbial biomass nitrogen（SMBN）were positively correlated with SOC. The content of easily oxidized carbon（EOC）, particulate organic carbon（POC） and light fraction organic carbon（LFOC） decreased with depth increasing and the content were the lowest in the 60 cm to 100 cm depth.The total SOC, ROC and POC contents decreased with increasing soil horizons. The SOC, TN, MBC and MBN contents increased with increasing altitude in the Sygera Mountains. The MBC and MBN contents weredifferent with the changes of SOC（p＆lt;0.05）,meanwhile, both LFOC and POC were related to total SOC（p＆lt;0.05）. The physical and chemical properties of soil, including temperature, humidity, and altitude,were involved in the regulation of SOC, TN, MBC,MBN and LFOC contents in the Sygera Mountains,Tibetan Plateau.展开更多
Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for th...Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.展开更多
This study was carried out in paddy fields to explore how organic manure applications would affect greenhouse emissions in South China. The results showed that the seasonal emission of CH4 under the chemical fertiliz...This study was carried out in paddy fields to explore how organic manure applications would affect greenhouse emissions in South China. The results showed that the seasonal emission of CH4 under the chemical fertilizer （CF） treatment was 271.47 kg/hm^2. In comparison, the seasonal emissions of CH4 under the treatment of pig manure （PM）, chicken manure （CM） and rice straw （RS） increased by 50.61,260.22 and 602.82 kg/hm^2, respectively. N2O emission under the CF treatment was 1.22 kg/hm^2, while the N20 seasonal emissions under tile PM, CM and RS treatment decreased by 23.6% （P〈0.05）, 31.7% （P〈0.05） and 30.9% （P〈0.05）, respectively. Meanwhile, the readily oxidized organic carbon （which was oxidized by 167 mmol/L potassium permanganate, ROC167） of manure, paddy soil Eh value and temperature could also affect the CH4 emissions. The average yield of the organic fertilizer treatments increased by 6.8% compared with that of the CF treatment. Among all the organic fertilizer treatments, the PM treatment offered the lowest global warming potential and greenhouse gas intensity, in which the PM was of no significant difference from NF （no fertilizing） and CF. Therefore, the pig manure is capable of coordinating the relationship between environment and yield, and it also has a low ROC167 content, so the PM is considered worthy of recommendation.展开更多
Multi-biomarker indexes were analyzed for two piston cores from potential cold seep areas of the South China Sea off southwestern Taiwan. Total organic carbon（TOC） normalized terrestrial（n-alkanes） and marine（bra...Multi-biomarker indexes were analyzed for two piston cores from potential cold seep areas of the South China Sea off southwestern Taiwan. Total organic carbon（TOC） normalized terrestrial（n-alkanes） and marine（brassicasterol, dinosterol, alkenones and iso-GDGTs） biomarker contents and ratios（TMBR, 1/Pmar-aq, BIT） were used to evaluate the contributions of terrestrial and marine organic matter（TOM and MOM respectively） to the sedimentary organic matter, indicating that MOM dominated the organic sources in Core MD052911 and the sedimentary organic matter in Core ORI-_（86）0-22 was mainly derived from terrestrial inputs, and different morphologies were the likely reason for TOM percentage differences. BIT results suggested that river-transported terrestrial soil organic matter was not a major source of TOM of sedimentary organic matter around these settings.Diagnostic biomarkers for methane-oxidizing archaea（MOA） were only detected in one sample at 172 cm depth of Core ORI-_（86）0-22, with abnormally high iso-GDGTs content and Methane Index（MI） value（0.94）. These results indicated high anaerobic oxidation of methane（AOM） activities at or around 172 cm in Core ORI-_（86）0-22.However in Core MD052911, MOA biomarkers were not detected and MI values were lower（0.19–0.38）, indicated insignificant contributions of iso-GDGTs from methanotrophic archaea and the absence of significant AOM activities. Biomarker results thus indicated that the discontinuous upward methane seepage and insufficient methane flux could not induce high AOM activities in our sampling sites. In addition, the different patterns of TEX_（86） and U_（37）^（K′） temperature in two cores suggested that AOM activities affected TEX_（86）37 temperature estimates with lower values in Core ORI-_（86）0-22, but not significantly on TEX_（86） temperature estimates in Core MD052911.展开更多
Metal sulfides as a feasible candidate with high specific capacitance for supercapacitors suffer from sluggish ion/electron transport kinetics and rapid capacitance fading. Herein, we demonstrate a method to fabricate...Metal sulfides as a feasible candidate with high specific capacitance for supercapacitors suffer from sluggish ion/electron transport kinetics and rapid capacitance fading. Herein, we demonstrate a method to fabricate a composite of reduced graphene oxide（rGO） with hollow Co9S8 derived from metal organic framework（MOF）. Due to the combined highly conductive rGO substrates and hollow shell, the prepared r GO/Co9S8 composite exhibits a high specific capacitance of 575.9 F/g at 2 A/g and 92.0% capacitance retention after 9000 cycles. Its excellent electrochemical performance provides great promise for application, and this versatile method can be extended to prepare other similar nanocomposite.展开更多
The octahedral molecular sieve(OMS-2)-supported Fe( xFe/OMS-2: x = 1, 3, 5, and 10) catalysts were prepared using the pre-incorporation method. Physicochemical properties of the as-synthesized materials were character...The octahedral molecular sieve(OMS-2)-supported Fe( xFe/OMS-2: x = 1, 3, 5, and 10) catalysts were prepared using the pre-incorporation method. Physicochemical properties of the as-synthesized materials were characterized by means of various techniques, and their catalytic activities for CO, ethyl acetate, and toluene oxidation were evaluated. Among all of the samples, performed the best, with the reaction temperature required to achieve 90% conversion( T 90%) being 160 ℃ for CO oxidation, 210 ℃ for ethyl acetate oxidation, and 285 ℃ for toluene oxidation. Such a good catalytic performance of 5Fe/OMS-2 was associated with its high(Mn^(3+) + Mn^(2+)) content and adsorbed oxygen species concentration, and good lowtemperature reducibility and lattice oxygen mobility as well as strong interaction between Fe and OMS-2. In addition, catalytic mechanisms of the oxidation of three pollutants over the 5Fe/OMS-2 catalyst were also studied. It was found that CO, ethyl acetate or toluene was first adsorbed, then the related intermediates were formed, and finally the formed intermediates were completely converted into CO_(2) and H_(2)O.展开更多
High-surface-area mesoprous powders of γ-Al2O3 doped with Cu^2＋, Cr^3＋, and V^3＋ ions were prepared uia a modified sol-gel method and were investigated as catalysts for the oxidation of chlorinated organic compoun...High-surface-area mesoprous powders of γ-Al2O3 doped with Cu^2＋, Cr^3＋, and V^3＋ ions were prepared uia a modified sol-gel method and were investigated as catalysts for the oxidation of chlorinated organic compounds. The composites retained high surface areas and pore volumes comparable with those of undoped γ-Al2O3 and the presence of the transition metal ions enhanced their surface acidic properties. The catalytic activity of the prepared catalysts in the oxidation of 1,2-dichloroethane （DCE） was studied in the temperature range of 250-400℃. The catalytic activity and product selectivity were strongly dependent on the presence and the type of dopant ion. While Cu^2＋- and Cr^3＋-containing catalysts showed 100% conversion at 300℃ and 350℃, V3＋-containing catalyst showed considerably lower conversion. Furthermore, while the major products of the reactions over γ-alumina were vinyl chloride （C2H3Cl） and hydrogen chloride （HCl） at all temperatures, Cu- and Cr-doped catalysts showed siguiticantly stronger capability for deep oxidation to CO2.展开更多
Photoelectrocatalysis(PEC)is a promising approach that can convert renewable solar energy into chemical energy,while most concern is concentrated on PEC water splitting to obtain high‐value‐added fuel—hydrogen.In p...Photoelectrocatalysis(PEC)is a promising approach that can convert renewable solar energy into chemical energy,while most concern is concentrated on PEC water splitting to obtain high‐value‐added fuel—hydrogen.In practice,more economic benefits can be produced based on PEC technique,such as H_(2)O oxidative H_(2)O_(2) synthesis,organic selective oxidation,organic pollutants degradation and CO_(2) reduction.Although there are plenty of excellent reviews focusing on the PEC water splitting system,the production of various high‐value‐added chemicals in PEC systems has not been discussed synthetically.This Account will focus on the production process of various high‐value‐added chemicals through PEC technology.The photoelectrode design,reaction environment and working mechanisms of PEC systems are also discussed in detail.We believe that this comprehensive Account of the expanded application of photoelectrocatalysis can add an inestimable impetus to the follow‐up development of this technology.展开更多
Renewable energy-driven hydrogen generation from water electrolysis has been widely recognized as a promising approach to utilize sustainable energy resources,reduce our dependence on legacy fossil fuels and alleviate...Renewable energy-driven hydrogen generation from water electrolysis has been widely recognized as a promising approach to utilize sustainable energy resources,reduce our dependence on legacy fossil fuels and alleviate net carbon dioxide emissions.However,conventional water electrolyzers suffer from the high overpotentials,mainly due to the sluggish kinetics of anodic oxygen evolution reaction(OER).This reaction also generates reactive oxygen species that could degrade the proton exchange membrane and oxygen that may mix with the cathodic hydrogen to form explosive gaseous mixtures.To address these issues,an innovative hybrid water electrolysis strategy which involves a certain alternative oxidation reaction to replace OER has been developed,and has led to a burgeoning area that sparks much research interest in finding available alternative reactions and their corresponding electrocatalysts.Herein,we summarize the alternative reactions into three groups:(1)the reagentsacrificing type that can generate H2 with an ultra-low potential while the substrates are oxidized to valueless products;(2)the pollutant-degrading type at which environmental pollutants are used as substrates;(3)the valueadded type that produces valuable products at the anode.Catalyst and electrolyzer designs for hybrid electrolysis are also briefly discussed,with an emphasis on the catalyst reconstruction phenomenon.Finally,the present challenges and perspectives are put forward.展开更多
Objective The study aim was to investigate the effects of exposure to multiple environmental organic pollutants on cardiopulmonary health with a focus on the potential mediating role of oxidative stress.Methods A repe...Objective The study aim was to investigate the effects of exposure to multiple environmental organic pollutants on cardiopulmonary health with a focus on the potential mediating role of oxidative stress.Methods A repeated-measures randomized crossover study involving healthy college students in Beijing was conducted.Biological samples,including morning urine and venous blood,were collected to measure concentrations of 29 typical organic pollutants,including hydroxy polycyclic aromatic hydrocarbons(OH-PAHs),bisphenol A and its substitutes,phthalates and their metabolites,parabens,and five biomarkers of oxidative stress.Health assessments included blood pressure measurements and lung function indicators.Results Urinary concentrations of 2-hydroxyphenanthrene(2-OH-PHE)(β=4.35%[95%confidence interval(CI):0.85%,7.97%]),3-hydroxyphenanthrene(β=3.44%[95%CI:0.19%,6.79%]),and 4-hydroxyphenanthrene(4-OH-PHE)(β=5.78%[95%CI:1.27%,10.5%])were significantly and positively associated with systolic blood pressure.Exposures to 1-hydroxypyrene(1-OH-PYR)(β=3.05%[95%CI:−4.66%,−1.41%]),2-OH-PHE(β=2.68%[95%CI:−4%,−1.34%]),and 4-OH-PHE(β=3%[95%CI:−4.68%,−1.29%])were negatively associated with the ratio of forced expiratory volume in the first second to forced vital capacity.These findings highlight the adverse effects of exposure to multiple pollutants on cardiopulmonary health.Biomarkers of oxidative stress,including 8-hydroxy-2'-deoxyguanosine and extracellular superoxide dismutase,mediated the effects of multiple OH-PAHs on blood pressure and lung function.展开更多
A series of crystalline compounds were obtained from simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate and different Keggin polyoxometalates. Phosphotungstic acid immobilized in host matrix ...A series of crystalline compounds were obtained from simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate and different Keggin polyoxometalates. Phosphotungstic acid immobilized in host matrix was selected for the first time as a recyclable and efficient catalyst in oxidative desulfurization process, under eco-sustainable conditions supported by the green oxidant O2 and the green extracting agent distilled water. The efficiency of desulfurization with air was studied and it is possible to use air as green oxidant in desulfurization. Moreover, the catalyst is effective for the desulfurization of real diesel.展开更多
A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60...A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.展开更多
Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene ...Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1：2：4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the Ce O2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.展开更多
A total of 15 light-duty diesel vehicles（LDDVs） were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hy...A total of 15 light-duty diesel vehicles（LDDVs） were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hydrocarbons（HC） and nitrogen oxides（NOx） at different speeds, chemical species profiles and ozone formation potential（OFP） of volatile organic compounds（VOCs） emitted from diesel vehicles with different emission standards were analyzed. The results demonstrated that emission reductions of HC and NOxhad been achieved as the control technology became more rigorous from Stage I to Stage IV. It was also found that the HC and NOxemissions and percentage of O2 dropped with the increase of speed, while the percentage of CO2 increased. The abundance of alkanes was significantly higher in diesel vehicle emissions, approximately accounting for 41.1%–45.2%, followed by aromatics and alkenes. The most abundant species were propene,ethane, n-decane, n-undecane, and n-dodecane. The maximum incremental reactivity（MIR）method was adopted to evaluate the contributions of individual VOCs to OFP. The results indicated that the largest contributors to O3 production were alkenes and aromatics, which accounted for 87.7%–91.5%. Propene, ethene, 1,2,4-trimethylbenzene, 1-butene, and1,2,3-trimethylbenzene were the top five VOC species based on their OFP, and accounted for 54.0%-64.8% of the total OFP. The threshold dilution factor was applied to analyze the possibility of VOC stench pollution. The majority of stench components emitted from vehicle exhaust were aromatics, especially p-diethylbenzene, propylbenzene, m-ethyltoluene, and p-ethyltoluene.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22272026 and 22272028)the 111 Project(No.D16008)Jinhong Bi thanks the Youth Talent Support Program of Fujian Province(No.00387077).
文摘Defect engineering in metal organic frameworks(MOFs)has captured significant attention in the field of photocatalysis.A series of UiO-66(Ce)(UiO=University of Oslo)MOFs with different contents of missing-linker defects have been developed for the photocatalytic selective oxidation of benzylamine(BA)and thioanisole(TA)under visible light.The introduction of missing-linker defects promotes the formation of unsaturated Ce sites with a high Ce3+content.It also generates a high concentration of oxygen vacancies.In situ Fourier transform infrared spectroscopy(FTIR)results revealed that BA and TA molecules were activated on coordinatively unsaturated Ce sites via the H-N…Ce and the C-S…Ce interactions,respectively.Simulated in situ electron paramagnetic resonance(EPR)data indicate that O_(2) activation and reduction occur at coordinatively unsaturated Ce^(3+)sites to form·O_(2)^(-).This is accelerated by the Ce^(3+)/Ce^(4+)redox cycle associated with the photogenerated electrons.The corresponding photogenerated holes are involved in the deprotonation of the activated BA and TA.The most active sample exhibits 98.4%and 95.5%conversion rates for BA and TA oxidation.Mechanisms for the molecular activation are proposed at the molecular level.
基金supported by Jiangxi Province Key Laboratory of Synthetic Chemistry(JXSC202004)the Foundation of Jiangxi Educational Committee(GJJ200731)the Natural Science Foundation of Jiangxi Province of China(20192BAB213001)。
文摘The rational fabrication of photocatalysts with dual functions upon visible light, such as photocatalytic radioactive U(Ⅵ)reduction and value-added organic oxidation, is highly desirable but remains huge challenge. Here, we couple the photocatalytic U(Ⅵ) reduction with the oxidative organic synthesis to one system using novel extended π-conjugated framework(Cu@ThTCPP) without the expense of sacrificial reagents. Noticeably, the as-prepared Cu@Th-TCPP linked by tetratopic tetrakis(4-carboxyphenyl)porphyrin(TCPP) ligand and unique Th(μ-O)(HCOO)(HO)secondary building unit(SBU) exhibits significantly enhanced activity when the photocatalytic U(Ⅵ) reduction and thioanisole oxidation were integrated to one system.Further experimental characterizations demonstrate that the highly conjugated framework of Cu@Th-TCPP is good for the charge transfer and separation, while incorporating Cusite further accelerates the charge-carrier dynamics, thus giving rise to the dual-functional property. Apparently, this strategy conforms to atomic economy, opens a new horizon to address radioactive environmental pollution in natural water systems and soils, and simultaneously produces valuable chemicals.
基金supported by the Open Research Fund of Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Sciences (No. JJ-10-04)the National Natural Science Foundation of China (No.40975080, 10979061)class A technology fund of Department of Education of Fujian Province (No. JA11290)
文摘Secondary organic aerosol （SOA） formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer （ALTOFMS）, respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 μm （i.e., PM2.5）, and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.
文摘A simple and effective method of removing polluted organics in water is reported here.Titanium dioxide is a catalyst in photo-oxidation of monocrotophos.The mechanism of photocatalytic oxidation and the kinetics of the reaction were studied. This same principle also leads to the construction of instrument of PTR-FIA analysis for monitoring organic phosphorus and phosphate in water.
基金jointly supported by the National Natural Science Foundation of China(No.41161047)the Scientific Development and Technology Innovation Project of Xinjiang Production and Construction Group(XPCG)in China(No.2017BA041)。
文摘Investigating the impacts of soil conversion on soil organic carbon(OC) content and its fractions within soil aggregates is essential for defining better strategies to improve soil structure and OC sequestration in terrestrial ecosystems. However, the consequences of soil conversion from paddy soil to upland soil for soil aggregates and intra-aggregate OC pools are poorly understood. Therefore, the objective of this study was to quantify the effects of soil conversion on soil aggregate and intra-aggregate OC pool distributions. Four typical rice-producing areas were chosen in North and South China, paired soil samples(upland soil converted from paddy soil more than ten years ago vs. adjacent paddy soil) were collected(0–20 cm) with three replicates in each area. A set of core parameters(OC preservation capacity, aggregate carbon(C) turnover, and biological activity index) were evaluated to assess the responses of intra-aggregate OC turnover to soil conversion. Results showed that soil conversion from paddy soil to upland soil significantly improved the formation of macro-aggregates and increased aggregate stability. It also notably decreased soil intra-aggregate OC pools, including easily oxidized OCa(EOCa), particulate OCa(POCa), and mineral-bound(MOCa) OC, and the sensitivity of aggregate-associated OC pools to soil conversion followed the order: EOCa(average reduction of 21.1%) > MOCa(average reduction of 15.4%) > POCa(average reduction of 14.8%). The potentially mineralizable C(C_(0)) was significantly higher in upland soil than in paddy soil, but the corresponding decay constant(k) was lower in upland soil than in paddy soil. Random forest model and partial correlation analysis showed that EOCa and pH were the important nutrient and physicochemical factors impacting k of C mineralization in paddy soil,while MOCa and C-related enzyme(β-D-cellobiohydrolase) were identified as the key factors in upland soil. In conclusion, this study evidenced that soil conversion from paddy soil to upland soil increased the percentage of macro-aggregates and aggregate stability, while decreased soil aggregate-associated C stock and k of soil C mineralization on a scale of ten years. Our findings provided some new insights into the alterations of soil aggregates and potential C sequestration under soil conversion system in rice-producing areas.
基金supported by the National Key R&D Program of China(2017YFC0211503,2016YFC0207100)the Strategic Priority Research Program(A)of the Chinese Academy of Sciences(XDA23030300)+2 种基金the National Natural Science Foundation of China(21401200,51672273)the Open Research Fund of State Key Laboratory of Multi-phase Complex Systems(MPCS-2017-D-06)the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment,CAS(CERAE201805)~~
文摘Catalytic oxidation is regarded as one of the most promising strategies for volatile organic compounds(VOCs)purification.Mixed metal oxides(MMOs),after topological transformation using layered double hydroxides(LDHs)as precursors,are extensively used as catalysts for VOCs oxidation due to their uniformity advantage.This review summarizes the developments in the LDH-derived VOCs heterogeneous catalytic oxidation over the last 10 years.Particularly,it addresses the VOCs abatement performance over MMO,noble metal/MMO,core-shell structured MMO,and integral MMO film catalysts originating from LDHs.Moreover,it highlights the water vapor effect and oxidation mechanism.This review indicates that LDH-based catalysts are a category of important VOCs oxidation materials.
基金supported by CFERN & GENE Award Funds on Ecological Paper
文摘Labile organic carbon（LOC） is one of the most important indicators of soil organic matter quality and dynamics elevation and plays important function in the Tibetan Plateau climate. However, it is unknown what the sources and causes of LOC contamination are. In this study, soil organic carbon（SOC）, total nitrogen（TN）, microbial biomass carbon（MBC）, microbial biomass nitrogen（MBN） and LOC were analyzed based on different soil horizons and elevations using turnover time in an experimental site（3700 m to 4300 m area） in Sygera. SOC and LOC in higher-elevation vegetation types were higher than that of in lower-elevation vegetation types. Our results presented that the soil microbial biomass carbon（SMBC） and soil microbial biomass nitrogen（SMBN）were positively correlated with SOC. The content of easily oxidized carbon（EOC）, particulate organic carbon（POC） and light fraction organic carbon（LFOC） decreased with depth increasing and the content were the lowest in the 60 cm to 100 cm depth.The total SOC, ROC and POC contents decreased with increasing soil horizons. The SOC, TN, MBC and MBN contents increased with increasing altitude in the Sygera Mountains. The MBC and MBN contents weredifferent with the changes of SOC（p＆lt;0.05）,meanwhile, both LFOC and POC were related to total SOC（p＆lt;0.05）. The physical and chemical properties of soil, including temperature, humidity, and altitude,were involved in the regulation of SOC, TN, MBC,MBN and LFOC contents in the Sygera Mountains,Tibetan Plateau.
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (No. 2012R1A1B3002152, 2013R1A2A2A03016095)
文摘Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.
文摘This study was carried out in paddy fields to explore how organic manure applications would affect greenhouse emissions in South China. The results showed that the seasonal emission of CH4 under the chemical fertilizer （CF） treatment was 271.47 kg/hm^2. In comparison, the seasonal emissions of CH4 under the treatment of pig manure （PM）, chicken manure （CM） and rice straw （RS） increased by 50.61,260.22 and 602.82 kg/hm^2, respectively. N2O emission under the CF treatment was 1.22 kg/hm^2, while the N20 seasonal emissions under tile PM, CM and RS treatment decreased by 23.6% （P〈0.05）, 31.7% （P〈0.05） and 30.9% （P〈0.05）, respectively. Meanwhile, the readily oxidized organic carbon （which was oxidized by 167 mmol/L potassium permanganate, ROC167） of manure, paddy soil Eh value and temperature could also affect the CH4 emissions. The average yield of the organic fertilizer treatments increased by 6.8% compared with that of the CF treatment. Among all the organic fertilizer treatments, the PM treatment offered the lowest global warming potential and greenhouse gas intensity, in which the PM was of no significant difference from NF （no fertilizing） and CF. Therefore, the pig manure is capable of coordinating the relationship between environment and yield, and it also has a low ROC167 content, so the PM is considered worthy of recommendation.
基金The National Natural Science Foundation of China under contract No.41521064the Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology under contract No.MRE201301
文摘Multi-biomarker indexes were analyzed for two piston cores from potential cold seep areas of the South China Sea off southwestern Taiwan. Total organic carbon（TOC） normalized terrestrial（n-alkanes） and marine（brassicasterol, dinosterol, alkenones and iso-GDGTs） biomarker contents and ratios（TMBR, 1/Pmar-aq, BIT） were used to evaluate the contributions of terrestrial and marine organic matter（TOM and MOM respectively） to the sedimentary organic matter, indicating that MOM dominated the organic sources in Core MD052911 and the sedimentary organic matter in Core ORI-_（86）0-22 was mainly derived from terrestrial inputs, and different morphologies were the likely reason for TOM percentage differences. BIT results suggested that river-transported terrestrial soil organic matter was not a major source of TOM of sedimentary organic matter around these settings.Diagnostic biomarkers for methane-oxidizing archaea（MOA） were only detected in one sample at 172 cm depth of Core ORI-_（86）0-22, with abnormally high iso-GDGTs content and Methane Index（MI） value（0.94）. These results indicated high anaerobic oxidation of methane（AOM） activities at or around 172 cm in Core ORI-_（86）0-22.However in Core MD052911, MOA biomarkers were not detected and MI values were lower（0.19–0.38）, indicated insignificant contributions of iso-GDGTs from methanotrophic archaea and the absence of significant AOM activities. Biomarker results thus indicated that the discontinuous upward methane seepage and insufficient methane flux could not induce high AOM activities in our sampling sites. In addition, the different patterns of TEX_（86） and U_（37）^（K′） temperature in two cores suggested that AOM activities affected TEX_（86）37 temperature estimates with lower values in Core ORI-_（86）0-22, but not significantly on TEX_（86） temperature estimates in Core MD052911.
基金Financial support from National Key Project (No. 2017YFF0210703)Distinguished Young Scientists Program of the National Natural Science Foundation of China (Nos. 51425301, 21374021, 51673096 and U1601214)
文摘Metal sulfides as a feasible candidate with high specific capacitance for supercapacitors suffer from sluggish ion/electron transport kinetics and rapid capacitance fading. Herein, we demonstrate a method to fabricate a composite of reduced graphene oxide（rGO） with hollow Co9S8 derived from metal organic framework（MOF）. Due to the combined highly conductive rGO substrates and hollow shell, the prepared r GO/Co9S8 composite exhibits a high specific capacitance of 575.9 F/g at 2 A/g and 92.0% capacitance retention after 9000 cycles. Its excellent electrochemical performance provides great promise for application, and this versatile method can be extended to prepare other similar nanocomposite.
基金supported by the National Natural Science Foundation of China (Nos. 21277008 and 20777005)National Key Research and Development Program of China (No. 2017YFC0209905)Natural Science Foundation of Beijing (No. 8082008 )。
文摘The octahedral molecular sieve(OMS-2)-supported Fe( xFe/OMS-2: x = 1, 3, 5, and 10) catalysts were prepared using the pre-incorporation method. Physicochemical properties of the as-synthesized materials were characterized by means of various techniques, and their catalytic activities for CO, ethyl acetate, and toluene oxidation were evaluated. Among all of the samples, performed the best, with the reaction temperature required to achieve 90% conversion( T 90%) being 160 ℃ for CO oxidation, 210 ℃ for ethyl acetate oxidation, and 285 ℃ for toluene oxidation. Such a good catalytic performance of 5Fe/OMS-2 was associated with its high(Mn^(3+) + Mn^(2+)) content and adsorbed oxygen species concentration, and good lowtemperature reducibility and lattice oxygen mobility as well as strong interaction between Fe and OMS-2. In addition, catalytic mechanisms of the oxidation of three pollutants over the 5Fe/OMS-2 catalyst were also studied. It was found that CO, ethyl acetate or toluene was first adsorbed, then the related intermediates were formed, and finally the formed intermediates were completely converted into CO_(2) and H_(2)O.
基金United Arab Emirates University through NRF grant, 2011
文摘High-surface-area mesoprous powders of γ-Al2O3 doped with Cu^2＋, Cr^3＋, and V^3＋ ions were prepared uia a modified sol-gel method and were investigated as catalysts for the oxidation of chlorinated organic compounds. The composites retained high surface areas and pore volumes comparable with those of undoped γ-Al2O3 and the presence of the transition metal ions enhanced their surface acidic properties. The catalytic activity of the prepared catalysts in the oxidation of 1,2-dichloroethane （DCE） was studied in the temperature range of 250-400℃. The catalytic activity and product selectivity were strongly dependent on the presence and the type of dopant ion. While Cu^2＋- and Cr^3＋-containing catalysts showed 100% conversion at 300℃ and 350℃, V3＋-containing catalyst showed considerably lower conversion. Furthermore, while the major products of the reactions over γ-alumina were vinyl chloride （C2H3Cl） and hydrogen chloride （HCl） at all temperatures, Cu- and Cr-doped catalysts showed siguiticantly stronger capability for deep oxidation to CO2.
文摘Photoelectrocatalysis(PEC)is a promising approach that can convert renewable solar energy into chemical energy,while most concern is concentrated on PEC water splitting to obtain high‐value‐added fuel—hydrogen.In practice,more economic benefits can be produced based on PEC technique,such as H_(2)O oxidative H_(2)O_(2) synthesis,organic selective oxidation,organic pollutants degradation and CO_(2) reduction.Although there are plenty of excellent reviews focusing on the PEC water splitting system,the production of various high‐value‐added chemicals in PEC systems has not been discussed synthetically.This Account will focus on the production process of various high‐value‐added chemicals through PEC technology.The photoelectrode design,reaction environment and working mechanisms of PEC systems are also discussed in detail.We believe that this comprehensive Account of the expanded application of photoelectrocatalysis can add an inestimable impetus to the follow‐up development of this technology.
基金We acknowledge the financial support from the Start-up Funding of the Huazhong University of Science and Technology(HUST)and the Program for HUST Academic Frontier Youth Team(2018QYTD15).
文摘Renewable energy-driven hydrogen generation from water electrolysis has been widely recognized as a promising approach to utilize sustainable energy resources,reduce our dependence on legacy fossil fuels and alleviate net carbon dioxide emissions.However,conventional water electrolyzers suffer from the high overpotentials,mainly due to the sluggish kinetics of anodic oxygen evolution reaction(OER).This reaction also generates reactive oxygen species that could degrade the proton exchange membrane and oxygen that may mix with the cathodic hydrogen to form explosive gaseous mixtures.To address these issues,an innovative hybrid water electrolysis strategy which involves a certain alternative oxidation reaction to replace OER has been developed,and has led to a burgeoning area that sparks much research interest in finding available alternative reactions and their corresponding electrocatalysts.Herein,we summarize the alternative reactions into three groups:(1)the reagentsacrificing type that can generate H2 with an ultra-low potential while the substrates are oxidized to valueless products;(2)the pollutant-degrading type at which environmental pollutants are used as substrates;(3)the valueadded type that produces valuable products at the anode.Catalyst and electrolyzer designs for hybrid electrolysis are also briefly discussed,with an emphasis on the catalyst reconstruction phenomenon.Finally,the present challenges and perspectives are put forward.
基金supported by the National Key Research&Development Program of the Ministry of Science and Technology of China(2022YFE0134900,2023YFC3708305,2023YFC3708302)Strategy Priority Research Program(Category B)of the Chinese Academy of Sciences(No.XDB0750300)National Natural Science Foundation of China(Grant No.42477455,42077390).
文摘Objective The study aim was to investigate the effects of exposure to multiple environmental organic pollutants on cardiopulmonary health with a focus on the potential mediating role of oxidative stress.Methods A repeated-measures randomized crossover study involving healthy college students in Beijing was conducted.Biological samples,including morning urine and venous blood,were collected to measure concentrations of 29 typical organic pollutants,including hydroxy polycyclic aromatic hydrocarbons(OH-PAHs),bisphenol A and its substitutes,phthalates and their metabolites,parabens,and five biomarkers of oxidative stress.Health assessments included blood pressure measurements and lung function indicators.Results Urinary concentrations of 2-hydroxyphenanthrene(2-OH-PHE)(β=4.35%[95%confidence interval(CI):0.85%,7.97%]),3-hydroxyphenanthrene(β=3.44%[95%CI:0.19%,6.79%]),and 4-hydroxyphenanthrene(4-OH-PHE)(β=5.78%[95%CI:1.27%,10.5%])were significantly and positively associated with systolic blood pressure.Exposures to 1-hydroxypyrene(1-OH-PYR)(β=3.05%[95%CI:−4.66%,−1.41%]),2-OH-PHE(β=2.68%[95%CI:−4%,−1.34%]),and 4-OH-PHE(β=3%[95%CI:−4.68%,−1.29%])were negatively associated with the ratio of forced expiratory volume in the first second to forced vital capacity.These findings highlight the adverse effects of exposure to multiple pollutants on cardiopulmonary health.Biomarkers of oxidative stress,including 8-hydroxy-2'-deoxyguanosine and extracellular superoxide dismutase,mediated the effects of multiple OH-PAHs on blood pressure and lung function.
基金financial support from the National Natural Science Foundation of China (Nos. 20976097, 21076116, 21211120165, 21311120297)Petro China Scientific and Technical Innovation Project (No. 2010D-5006-0405)Natural Science Foundation of Shandong Province (No. ZR2011BM023)
文摘A series of crystalline compounds were obtained from simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate and different Keggin polyoxometalates. Phosphotungstic acid immobilized in host matrix was selected for the first time as a recyclable and efficient catalyst in oxidative desulfurization process, under eco-sustainable conditions supported by the green oxidant O2 and the green extracting agent distilled water. The efficiency of desulfurization with air was studied and it is possible to use air as green oxidant in desulfurization. Moreover, the catalyst is effective for the desulfurization of real diesel.
基金supported by the National Natural Science Foundation of China (Nos. 41475113, 41175018)the CAS Strategic Priority Research Program (No. XDB05010500)
文摘A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.
基金the financial support from the Natural Science Foundation of China (No. 21107096)Zhejiang Provincial Natural Science Foundation of China (No. Y14E080008)+1 种基金the Commission of Science and Technology of Zhejiang province (No. 2013C03021)the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20133317110004)
文摘Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1：2：4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the Ce O2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.
基金supported by the Natural Sciences Foundation of China(Nos.91544232&51408015)the Ministry of Environmental Protection Special Funds for Scientific Research on Public Causes(No.201409006)+4 种基金the Beijing municipal science and technology plan projects(No.Z131100001113029)the 13th graduate students of science and technology fund of Beijing University of Technology(ykj-2014-11484)the projects supported by Beijing Municipal Commission of Science and Technology(No.Z141100001014002)Beijing Municipal Commission of Education(No.PXM2016_014204_001029)National Science and Technology Support Project of China(No.2014BAC23B02)
文摘A total of 15 light-duty diesel vehicles（LDDVs） were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hydrocarbons（HC） and nitrogen oxides（NOx） at different speeds, chemical species profiles and ozone formation potential（OFP） of volatile organic compounds（VOCs） emitted from diesel vehicles with different emission standards were analyzed. The results demonstrated that emission reductions of HC and NOxhad been achieved as the control technology became more rigorous from Stage I to Stage IV. It was also found that the HC and NOxemissions and percentage of O2 dropped with the increase of speed, while the percentage of CO2 increased. The abundance of alkanes was significantly higher in diesel vehicle emissions, approximately accounting for 41.1%–45.2%, followed by aromatics and alkenes. The most abundant species were propene,ethane, n-decane, n-undecane, and n-dodecane. The maximum incremental reactivity（MIR）method was adopted to evaluate the contributions of individual VOCs to OFP. The results indicated that the largest contributors to O3 production were alkenes and aromatics, which accounted for 87.7%–91.5%. Propene, ethene, 1,2,4-trimethylbenzene, 1-butene, and1,2,3-trimethylbenzene were the top five VOC species based on their OFP, and accounted for 54.0%-64.8% of the total OFP. The threshold dilution factor was applied to analyze the possibility of VOC stench pollution. The majority of stench components emitted from vehicle exhaust were aromatics, especially p-diethylbenzene, propylbenzene, m-ethyltoluene, and p-ethyltoluene.
