SF_(6) has excellent insulation performance and arc extinguishing ability,and is widely used in the power industry.However,its global warming potential is about 23,500 times that of C0_(2),it can exist stably in the a...SF_(6) has excellent insulation performance and arc extinguishing ability,and is widely used in the power industry.However,its global warming potential is about 23,500 times that of C0_(2),it can exist stably in the atmosphere,it is not easily degradable and is of great potential harm to the environment.Based on pulsed dielectric barrier discharge plasma technology,the effects of H_(2)O and 0_(2) on the degradation of SF_(6) were studied.Studies have shown that H_(2)O can effectively promote the decomposition of SF_(6) and improve its degradation rate and energy efficiency of degradation.Under the action of a pulse input voltage and input frequency of 15 kV and 15 kHz,respectively,when H_(2)O is added alone the effect of 1% H_(2)O is the best,and the rate and energy efficiency of degradation of SF_(6) reach their maximum values,which are 91.9% and 8.25 g kWh^(-1),respectively.The synergistic effect of H_(2)O and O_(2) on the degradation of SF_(6) was similar to that of H_(2)O.When the concentration of H_(2)O and O_(2) was 1%,the system obtained the best rate and energy efficiency of degradation,namely 89.7% and 8.05 g kWh~(-1),respectively.At the same time,different external gases exhibit different capabilities to regulate decomposition products.The addition of H_(2)O can effectively improve the selectivity of S0_(2).Under the synergistic effect of H_(2)O and O_(2),with increase in O_(2) concentration the degradation products gradually transformed into SO_(2)F_(2).From the perspective of harmless treatment of the degradation products of SF_(6),the addition of O_(2) during the SF_(6) degradation process should be avoided.展开更多
Anatase TiO2 nanosheets(-ns-) with dominant exposed {001} facets were used as support to load copper,and the synthesized Cu/TiO2-ns catalysts were evaluated for CO2 hydrogenation to methanol. Under the reaction cond...Anatase TiO2 nanosheets(-ns-) with dominant exposed {001} facets were used as support to load copper,and the synthesized Cu/TiO2-ns catalysts were evaluated for CO2 hydrogenation to methanol. Under the reaction conditions, P = 3.0 MPa, T = 260 ℃, V(N2):V(H2):V(CO2) = 8:69:23 and gas hourly space velocity(GHSV) = 3600 mL g-1h-1, the methanol yield reached an appealing high value, 5.6%. Copper-loading amount, calcination temperature and reduction atmosphere have been investigated in this work, which significantly influence the particle sizes of copper and/or the defect concentration in TiO2, then leading to different catalytic performance. Characterizations of XRD, EPR, CO2-TPD and FTIR demonstrate that higher specific surface area of Cu is good for the hydrogenation of CO2 and adequate amount of Ti3+ plays important roles in CO2 activation. Both of them facilitate high turnover frequency(TOF) of methanol formation.展开更多
Herein,a bottom-down design is presented to successfully fabricate ZIF-derived Co3O4,grown in situ on a one-dimensional(1D)α-MnO2 material,denoted as α-MnO2@Co3O4.The synergistic effect derived from the coupled inte...Herein,a bottom-down design is presented to successfully fabricate ZIF-derived Co3O4,grown in situ on a one-dimensional(1D)α-MnO2 material,denoted as α-MnO2@Co3O4.The synergistic effect derived from the coupled interface constructed betweenα-MnO2 and Co3O4 is responsible for the enhanced catalytic activity.The resultantα-MnO2@Co3O4 catalyst exhibits excellent catalytic activity at a T90%(temperature required to achieve a toluene conversion of 90%)of approximately 229℃,which is 47 and 28℃ lower than those of the pureα-MnO2 nanowire and Co3O4-b obtained via pyrolysis of ZIF-67,respectively.This activity is attributed to the increase in the number of surface-adsorbed oxygen species,which accelerate the oxygen mobility and enhance the redox pairs of Mn^4+/Mn^3+ and Co^2+/Co^3+.Moreover,the result of in situ diffuse reflectance infrared Fourier transform spectroscopy suggests that the gaseous oxygen could be more easily activated to adsorbed oxygen species on the surface of α-MnO2@Co3O4 than on that of α-MnO2.The catalytic reaction route of toluene oxidation over theα-MnO2@Co3O4 catalyst is as follows:toluene→benzoate species→alkanes containing oxygen functional group→CO2 and H2O.In addition,the α-MnO2@Co3O4 catalyst shows excellent stability and good water resistance for toluene oxidation.Furthermore,the preparation method can be extended to other 1D MnO2 materials.A new strategy for the development of high-performance catalysts of practical significance is provided.展开更多
In an insulating system including solid and gas dielectrics, discharge type has a strong impact on charge accumulation at the interface between two dielectrics, and hence charge decay. In order to clarify the influenc...In an insulating system including solid and gas dielectrics, discharge type has a strong impact on charge accumulation at the interface between two dielectrics, and hence charge decay. In order to clarify the influence, a surface charge measurement system was constructed, and three types of discharge, i.e. surface discharge, and low intensity and high intensity coronas, were introduced to cause surface charge accumulation. The decay behavior of surface charges after different types of discharge was obtained at various temperatures. It was found that total surface charges monotonically decreased with time, and the decay rate became larger as temperature increased. However, after a surface discharge or a high intensity corona, surface charge density in the local area appeared to fluctuate during the decay process. Compared with this, the fluctuation of surface charge density was not observed after a low intensity corona. The mechanisms of surface charge accumulation and decay were analysed. Moreover, a microscopic physical model involving charge production, accumulation, and decay was proposed so that the experimental results could be explained.展开更多
Selective catalytic NH_(3)-to-N_(2) oxidation(NH_(3)-SCO)is highly promising for abating NH_(3) emissions slipped from stationary flue gas after-treatment devices.Its practical application,however,is limited by the no...Selective catalytic NH_(3)-to-N_(2) oxidation(NH_(3)-SCO)is highly promising for abating NH_(3) emissions slipped from stationary flue gas after-treatment devices.Its practical application,however,is limited by the non-availability of low-cost catalysts with high activity and N_(2) selectivity.Here,using defect-rich nitrogen-doped carbon nanotubes(NCNT-AW)as the support,we developed a highly active and durable copper-based NH_(3)-SCO catalyst with a high abundance of cuprous(Cu^(+))sites.The obtained Cu/NCNT-AW catalyst demonstrated outstanding activity with a T_(50)(i.e.the temperature to reach 50% NH_(3) conversion)of 174℃ in the NH_(3)-SCO reaction,which outperformed not only the Cu catalyst supported on N-free O-functionalized CNTs(OCNTs)or NCNT with less surface defects,but also those most active Cu catalysts in open literature.Reaction kinetics measurements and temperature-programmed surface reactions using NH_(3)as a probe molecule revealed that the NH_(3)-SCO reaction on Cu/NCNT-AW follows an internal selective catalytic reaction(i-SCR)route involving nitric oxide(NO)as a key intermediate.According to mechanistic investigations by X-ray photoelectron spectroscopy,Raman spectroscopy,and X-ray absorption spectroscopy,the superior NH_(3)-SCO performance of Cu/NCNT-AW originated from a synergy of surface defects and N-dopants.Specifically,surface defects promoted the anchoring of Cu O nanoparticles on N-containing sites and,thereby,enabled efficient electron transfer from N to Cu O,increasing significantly the fraction of SCR-active Cu^(+)sites in the catalyst.This study puts forward a new idea for manipulating and utilizing the interplay of defects and N-dopants on carbon surfaces to fabricate Cu^(+)-rich Cu catalysts for efficient abatement of slip NH_(3)emissions via selective oxidation.展开更多
Palladium-exchanged chabazite(Pd-CHA) zeolites as passive NO_x adsorbers(PNAs) enable efficient purification of nitrogen oxides(NO_x) in cold-start diesel exhausts. Their commercial application, however,is limited by ...Palladium-exchanged chabazite(Pd-CHA) zeolites as passive NO_x adsorbers(PNAs) enable efficient purification of nitrogen oxides(NO_x) in cold-start diesel exhausts. Their commercial application, however,is limited by the lack of facile preparation method. Here, high-performance CHA-type Pd-SAPO-34 zeolite was synthesized by a modified solid-state ion exchange(SSIE) method using PdO as Pd precursor,and demonstrated superior PNA performance as compared to Pd-SAPO-34 prepared by conventional wetchemistry strategies. Structural characterization using Raman spectroscopy and X-ray diffraction revealed that the SSIE method avoided water-induced damage to the zeolite framework during Pd loading. Mechanistic investigations on the SSIE process by in situ infrared spectroscopy and X-ray photoelectron spectroscopy disclosed that, while PdO precursor was mainly converted to Pd^(2+) cations coordinated to the zeolite framework by consuming the-OH groups of the zeolite, a portion of PdO could also undergo thermal decomposition to form highly dispersed Pd~0 clusters in the pore channels. This simplified and scalable SSIE method paves a new way for the cost-effective synthesis of defect-free high-performance Pd-SAPO-34 zeolites as PNA catalysts.展开更多
The buffer layer defects of high‐voltage crosslinked polyethylene(XLPE)cable occur frequently,which makes the detection method become the focus to be studied.Here,the broadband impedance detection technology for the ...The buffer layer defects of high‐voltage crosslinked polyethylene(XLPE)cable occur frequently,which makes the detection method become the focus to be studied.Here,the broadband impedance detection technology for the buffer layer defects of high‐voltage XLPE cables with corrugated aluminium sheath is investigated.There are nine cable samples,including new and defective ones.Some of the defective cables are artificial,and the other is retired cables.The influence of wiring mode,the circumferential relative position of electrodes,cable length,artificial white powder,artificial damp,and retired defective cables on the impedance spectrum is studied.It is found that the wiring mode of the insulation shield/aluminium sheath at the end of the cable can effectively detect the buffer layer defects.And the broadband impedance amplitude spectrum of the buffer layer in defective cable,measuring at various circumferential relative positions,is obviously different.When there are white powders,air gaps,or ablation in the buffer layer,the broadband impedance spectrum(BIS)will increase by several times.When the buffer layer is damped,the BIS will reduce.The research here provides theoretical support and technical methods for the buffer layer defects of XLPE cable with corrugated aluminium sheath.展开更多
Herein, we reported the synthesis of well-defined Co_3O_4 nanoarrays(NAs) supported on a monolithic three-dimensional macroporous nickel(Ni) foam substrate for use in highefficiency CO oxidation. The monolithic Co_3O_...Herein, we reported the synthesis of well-defined Co_3O_4 nanoarrays(NAs) supported on a monolithic three-dimensional macroporous nickel(Ni) foam substrate for use in highefficiency CO oxidation. The monolithic Co_3O_4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time,solvent polarity and deposition agent, these Co_3O_4 NAs catalysts exhibited various novel morphologies(single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co_3O_4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity(GHSV) 10,000 hr^(-1) and 150°C with longterm stability. Compared with the other Co_3O_4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites(Co^(3+)/Co^(2+)= 1.26).展开更多
A modified Hummer's method was adopted for the synthesis of graphene oxide(GO) and reduced graphene oxide(rGO). It was revealed that the modified method is effective for the production of GO and rGO from graphite...A modified Hummer's method was adopted for the synthesis of graphene oxide(GO) and reduced graphene oxide(rGO). It was revealed that the modified method is effective for the production of GO and rGO from graphite. Transmission electron microscopy(TEM) images of GO and rGO showed a sheet-like morphology. Because of the presence of oxygenated functional groups on the carbon surface, the interlayer spacing of the prepared GO was higher than that of rGO. The presence of /OH and CO groups in the Fourier transform infrared spectra(FTIR) spectrum and G-mode and 2D-mode in Raman spectra confirmed the synthesis of GO and rGO. rGO(292.6 m2/g) showed higher surface area than that of GO(236.4 m2/g). The prepared rGO was used as an adsorbent for benzene and toluene(model pollutants of volatile organic compounds(VOCs)) under dynamic adsorption/desorption conditions. rGO showed higher adsorption capacity and breakthrough times than GO. The adsorption capacity of rGO for benzene and toluene was 276.4 and 304.4 mg/g, respectively.Desorption experiments showed that the spent rGO can be successfully regenerated by heating at 150.0℃. Its excellent adsorption/desorption performance for benzene and toluene makes rGO a potential adsorbent for VOC adsorption.展开更多
Characteristics of toluene decomposition and formation of nitrogen oxide(NOx) by-products were investigated in a dielectric barrier discharge(DBD) reactor with/without catalyst at room temperature and atmospheric ...Characteristics of toluene decomposition and formation of nitrogen oxide(NOx) by-products were investigated in a dielectric barrier discharge(DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide(Mn Ox), iron oxide(Fe Ox), cobalt oxide(Co Ox) and copper oxide(Cu O), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density(SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the Cu O catalyst showed the best performance in NOx suppression. The Mn Ox catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.展开更多
Metal organic frameworks(MOFs)derivatives represented by quasi-MOFs have excellent physical and chemical properties and can be applied for the catalytic combustion of volatile organic compounds(VOCs).In this work,Pd/q...Metal organic frameworks(MOFs)derivatives represented by quasi-MOFs have excellent physical and chemical properties and can be applied for the catalytic combustion of volatile organic compounds(VOCs).In this work,Pd/quasi-Ce-BTC synthesized by simple one-step Npyrolysis was applied to the oxidation of toluene,showing excellent toluene catalytic activity(T_(90)=175℃,30000 mL/(g·h)).Microscopic analyses indicate the formation and interaction of a carbon matrix composite quasi-MOF structure interface.The results show that the amorphous carbon matrix formed during the partial pyrolysis of Ce-BTC significantly improves the adsorption and activation capacity of toluene in the reaction,and constructs a reductive system to maintain high concentrations of Ce^(3+)and Pd^(0),which can facilitate the activation and utilization of oxygen in reaction.Quasi in-situ XPS proves that carbon matrix is indirectly involved in the activation and storage of oxygen,and Pd^(0)is the crucial active site for the activation of oxygen.Stability and water resistance tests display good stability of Pd/quasi-Ce-BTC.This work provides a potential method for designing quasi-MOF catalysts towards VOCs effective abatement.展开更多
As an indispensable part of high-voltage direct current(HVDC)cable,the semiconductive shielding layer plays the role of uniforming electric field in the cable.However,cable shielding materials>35 kV mainly rely on ...As an indispensable part of high-voltage direct current(HVDC)cable,the semiconductive shielding layer plays the role of uniforming electric field in the cable.However,cable shielding materials>35 kV mainly rely on foreign imports in China,which belongs to the technical weak issues in the field of electrical materials.At present,there are few systematic reports on semiconductive shielding material of HVDC cable.In the work,the mechanisms of charge conduction and thermal conduction of semiconductive material have been introduced.Effect of raw material,carbon black content and the second conductive filler on the resistance characteristics of the semiconductive layer,the charge accumulation characteristics of the insulating layer and the interface characteristics have been studied.A kind of semiconductive layer as a high voltage terminal charge emission method has been proposed to study charge emission from the semiconducting layer to the insulation layer.This work can provide theoretical guidance for the research of semiconductive shielding materials.展开更多
As an environmental friendly insulating medium,C_(4)F_(7)N has received extensive attention in the past two years.In this study,the partial discharge(PD)and breakdown characteristics of C_(4)F_(7)N/CO_(2)gas mixture w...As an environmental friendly insulating medium,C_(4)F_(7)N has received extensive attention in the past two years.In this study,the partial discharge(PD)and breakdown characteristics of C_(4)F_(7)N/CO_(2)gas mixture were investigated using the gas insulation performance test platform.The influence of gas pressure and mixing ratio on the PD initial voltage(PDIV)and breakdown voltage of C_(4)F_(7)N/CO_(2)gas mixture in different electric fields was tested.It was found that the PDIV and breakdown voltage of gas mixture with 2-8%C_(4)F_(7)N in the highly non-uniform field showed a linear saturation increasing trend with the change of gas pressure and mixing ratio.The breakdown voltage of gas mixture increases linearly with gas pressure in the quasi-uniform electric field.The relative breakdown voltage of gas mixture in the highly non-uniform field under high-pressure conditions is inferior to those of low-pressure conditions.The C_(4)F_(7)N/CO_(2)gas mixture containing 2-8%C_(4)F_(7)N is sensitive to the non-uniformity of electric field.According to the PD and breakdown tests results,C_(4)F_(7)N/CO_(2)gas mixture with 2-8%C_(4)F_(7)N has the potential to replace SF6 using in gas-insulated equipment.展开更多
A facile hydrothermal method was applied to gain stably and highly efficient CuO-CeO_(2)(denoted as Cu1Ce2)catalyst for toluene oxidation.The changes of surface and inter properties on Cu1Ce2 were investigated compari...A facile hydrothermal method was applied to gain stably and highly efficient CuO-CeO_(2)(denoted as Cu1Ce2)catalyst for toluene oxidation.The changes of surface and inter properties on Cu1Ce2 were investigated comparing with pure CeO_(2)and pure CuO.The formation of Cu-Ce interface promotes the electron transfer between Cu and Ce through Cu^(2+)+Ce^(3+)↔Cu^(+)+Ce^(4+)and leads to high redox properties and mobility of oxygen species.Thus,the Cu1Ce2 catalyst makes up the shortcoming of CeO_(2)and CuO and achieved high catalytic performance with T_(50)=234°C and T_(99)=250°C(the temperature at which 50%and 90%C_(7)H_(8)conversion is obtained,respectively)for toluene oxidation.Different reaction steps and intermediates for toluene oxidation over Cu1Ce2,CeO_(2)and CuO were detected by in situ DRIFTS,the fast benzyl species conversion and preferential transformation of benzoates into carbonates through C=C breaking over Cu1Ce2 should accelerate the reaction.展开更多
The temperature of waste gas in refuse transfer station,airport smoking area,and RTO terminal is low,which needs deep oxidation.Catalytic ozonation is one of the most effective treatment techniques in these scenarios....The temperature of waste gas in refuse transfer station,airport smoking area,and RTO terminal is low,which needs deep oxidation.Catalytic ozonation is one of the most effective treatment techniques in these scenarios.In this study,we reported that catalysts were modified under the condition of mag-netic field to simulate the low temperature dynamic conditions of low concentration toluene for catalytic ozonation.This paper aims to explore the relationship between oxygen vacancy and active oxygen species,and the specific pathways of toluene oxidation.The study found that citric acid can enhance the syner-gistic effect between Mn and Ce,and promote the generation of oxygen vacancies.The surface molecule adsorption oxygen is more conducive to catalytic oxidation than subsurface atom adsorption oxygen.Fi-nally,we proposed the main pathways of toluene in this reaction system,which runs through the whole process of the reaction.展开更多
Herein,a facile glycol reduction route is successful employed to synthesize bimetallic Pt Ag alloys with homogeneous distribution of sizes and elements.Experimental studies reveal that the ultrafine Pt Ag alloys with ...Herein,a facile glycol reduction route is successful employed to synthesize bimetallic Pt Ag alloys with homogeneous distribution of sizes and elements.Experimental studies reveal that the ultrafine Pt Ag alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO_(2)microsphere,which remarkably enhances the catalytic performances for CO oxidation.Importantly,quasi in-situ X-ray photoelectron spectroscopy(XPS)result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by CO and O_(2)molecules,and the oxygen vacancy sites could be replenished and excited by gas-phase O_(2).展开更多
Ceria is widely used as a catalyst for soot combustion,but effects of Zr substitution on the reaction mechanism is ambiguous.The present work elucidates effects of Zr substitution on soot combustion over cubic fluorit...Ceria is widely used as a catalyst for soot combustion,but effects of Zr substitution on the reaction mechanism is ambiguous.The present work elucidates effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria.The nanostructured CeO_(2),Ce_(0.92)Zr_(0.08)O_(2),and Ce_(0.84)Zr_(0.16)O_(2)composed of 5-6 nm crystallites display T_(m-CO2)(the temperature at maximum CO_2 yield)at 383,355,and 375℃under 10 vol.%O_(2)/N_(2),respectively.The size of agglomerate decreases from 165.5 to 51.9-57.3 nm,which is beneficial for the sootceria contact.Moreover,Zr increases the amount of surface oxygen vacancies,generating more active oxygen(O_(2)^-and O^(-))for soot oxidation.Thus,the activities of Ce_(0.92)Zr_(0.08)O_(2)and Ce_(0.84)Zr_(0.16)O_(2)in soot combustion are better than that of CeO_(2).Although oxygen vacancies promote the migration of lattice O~(2-),the enriched surface Zr also inhibits the mobility of lattice O^(2-).Therefore,the T_(m-CO2)of Ce_(0.84)Zr_(0.1)6 O_(2)is higher than that of Ce_(0.92)Zr_(0.08)O_(2).Based on reaction kinetic study,soot in direct contact with ceria preferentially decomposes with low activation energy,while the oxidation of isolated soot occurs through diffusion with high activation energy.The obtained findings provide new understanding on the soot combustion over nanoceria.展开更多
The authors regret“In the whole text,ppm and mg/L was confusing.As in aqueous phase,1 ppm=1 mg/L,but in gaseous phase,1 ppm=0.001%o.In this paper,in text and figures,the concentration units were ppm,but when calculat...The authors regret“In the whole text,ppm and mg/L was confusing.As in aqueous phase,1 ppm=1 mg/L,but in gaseous phase,1 ppm=0.001%o.In this paper,in text and figures,the concentration units were ppm,but when calculating the adsorption ca-pacity,the concentration units ppm were mistakenly used as mg/L.As for benzene,1 ppm=3.4871 x 10^-3 mg/L,as for toluene。展开更多
基金supported by Guizhou Province (Ceneral), grant/award number Qian Ke He Zhi Cheng [2022] General 207, National Natural Science Foundation of China (No. 52307170)Natural Science Foundation of Hubei Province, China (No. 2023AFB382)。
文摘SF_(6) has excellent insulation performance and arc extinguishing ability,and is widely used in the power industry.However,its global warming potential is about 23,500 times that of C0_(2),it can exist stably in the atmosphere,it is not easily degradable and is of great potential harm to the environment.Based on pulsed dielectric barrier discharge plasma technology,the effects of H_(2)O and 0_(2) on the degradation of SF_(6) were studied.Studies have shown that H_(2)O can effectively promote the decomposition of SF_(6) and improve its degradation rate and energy efficiency of degradation.Under the action of a pulse input voltage and input frequency of 15 kV and 15 kHz,respectively,when H_(2)O is added alone the effect of 1% H_(2)O is the best,and the rate and energy efficiency of degradation of SF_(6) reach their maximum values,which are 91.9% and 8.25 g kWh^(-1),respectively.The synergistic effect of H_(2)O and O_(2) on the degradation of SF_(6) was similar to that of H_(2)O.When the concentration of H_(2)O and O_(2) was 1%,the system obtained the best rate and energy efficiency of degradation,namely 89.7% and 8.05 g kWh~(-1),respectively.At the same time,different external gases exhibit different capabilities to regulate decomposition products.The addition of H_(2)O can effectively improve the selectivity of S0_(2).Under the synergistic effect of H_(2)O and O_(2),with increase in O_(2) concentration the degradation products gradually transformed into SO_(2)F_(2).From the perspective of harmless treatment of the degradation products of SF_(6),the addition of O_(2) during the SF_(6) degradation process should be avoided.
基金financially supported by the National Natural Science Foundation of China (no. 91645119, 21207039, B5151050)the Fundamental Research Funds for the Central Universities (No.2017ZD076)+2 种基金Guangzhou science and technology plan (201607010095)the Natural Science Foundation of Guangdong Province, China (Grant no. S2011010000737)State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, P.R. China (No. 201602)
文摘Anatase TiO2 nanosheets(-ns-) with dominant exposed {001} facets were used as support to load copper,and the synthesized Cu/TiO2-ns catalysts were evaluated for CO2 hydrogenation to methanol. Under the reaction conditions, P = 3.0 MPa, T = 260 ℃, V(N2):V(H2):V(CO2) = 8:69:23 and gas hourly space velocity(GHSV) = 3600 mL g-1h-1, the methanol yield reached an appealing high value, 5.6%. Copper-loading amount, calcination temperature and reduction atmosphere have been investigated in this work, which significantly influence the particle sizes of copper and/or the defect concentration in TiO2, then leading to different catalytic performance. Characterizations of XRD, EPR, CO2-TPD and FTIR demonstrate that higher specific surface area of Cu is good for the hydrogenation of CO2 and adequate amount of Ti3+ plays important roles in CO2 activation. Both of them facilitate high turnover frequency(TOF) of methanol formation.
文摘Herein,a bottom-down design is presented to successfully fabricate ZIF-derived Co3O4,grown in situ on a one-dimensional(1D)α-MnO2 material,denoted as α-MnO2@Co3O4.The synergistic effect derived from the coupled interface constructed betweenα-MnO2 and Co3O4 is responsible for the enhanced catalytic activity.The resultantα-MnO2@Co3O4 catalyst exhibits excellent catalytic activity at a T90%(temperature required to achieve a toluene conversion of 90%)of approximately 229℃,which is 47 and 28℃ lower than those of the pureα-MnO2 nanowire and Co3O4-b obtained via pyrolysis of ZIF-67,respectively.This activity is attributed to the increase in the number of surface-adsorbed oxygen species,which accelerate the oxygen mobility and enhance the redox pairs of Mn^4+/Mn^3+ and Co^2+/Co^3+.Moreover,the result of in situ diffuse reflectance infrared Fourier transform spectroscopy suggests that the gaseous oxygen could be more easily activated to adsorbed oxygen species on the surface of α-MnO2@Co3O4 than on that of α-MnO2.The catalytic reaction route of toluene oxidation over theα-MnO2@Co3O4 catalyst is as follows:toluene→benzoate species→alkanes containing oxygen functional group→CO2 and H2O.In addition,the α-MnO2@Co3O4 catalyst shows excellent stability and good water resistance for toluene oxidation.Furthermore,the preparation method can be extended to other 1D MnO2 materials.A new strategy for the development of high-performance catalysts of practical significance is provided.
基金the financial support from National Natural Science Foundation of China (No. 51607128)Natural Science Foundation of Hubei Province (No. 2016CFB111)China Postdoctoral Science Foundation (No. 2016M602353)
文摘In an insulating system including solid and gas dielectrics, discharge type has a strong impact on charge accumulation at the interface between two dielectrics, and hence charge decay. In order to clarify the influence, a surface charge measurement system was constructed, and three types of discharge, i.e. surface discharge, and low intensity and high intensity coronas, were introduced to cause surface charge accumulation. The decay behavior of surface charges after different types of discharge was obtained at various temperatures. It was found that total surface charges monotonically decreased with time, and the decay rate became larger as temperature increased. However, after a surface discharge or a high intensity corona, surface charge density in the local area appeared to fluctuate during the decay process. Compared with this, the fluctuation of surface charge density was not observed after a low intensity corona. The mechanisms of surface charge accumulation and decay were analysed. Moreover, a microscopic physical model involving charge production, accumulation, and decay was proposed so that the experimental results could be explained.
基金supported by the National Natural Science Foundation of China(Nos.21806039,21976058)the Natural Science Foundation of Guangdong Province(No.2023A1515011682)+2 种基金the Fundamental Research Funds for the Central Universities(No.2022ZYGXZR018)the Science and Technology Program of Guangzhou(No.202102080490).P.C.appreciates the funding from the Pearl River Talent Recruitment Program of Guangdong Province(No.2019QN01L170)the Innovation&Entrepreneurship Talent Program of Shaoguan City。
文摘Selective catalytic NH_(3)-to-N_(2) oxidation(NH_(3)-SCO)is highly promising for abating NH_(3) emissions slipped from stationary flue gas after-treatment devices.Its practical application,however,is limited by the non-availability of low-cost catalysts with high activity and N_(2) selectivity.Here,using defect-rich nitrogen-doped carbon nanotubes(NCNT-AW)as the support,we developed a highly active and durable copper-based NH_(3)-SCO catalyst with a high abundance of cuprous(Cu^(+))sites.The obtained Cu/NCNT-AW catalyst demonstrated outstanding activity with a T_(50)(i.e.the temperature to reach 50% NH_(3) conversion)of 174℃ in the NH_(3)-SCO reaction,which outperformed not only the Cu catalyst supported on N-free O-functionalized CNTs(OCNTs)or NCNT with less surface defects,but also those most active Cu catalysts in open literature.Reaction kinetics measurements and temperature-programmed surface reactions using NH_(3)as a probe molecule revealed that the NH_(3)-SCO reaction on Cu/NCNT-AW follows an internal selective catalytic reaction(i-SCR)route involving nitric oxide(NO)as a key intermediate.According to mechanistic investigations by X-ray photoelectron spectroscopy,Raman spectroscopy,and X-ray absorption spectroscopy,the superior NH_(3)-SCO performance of Cu/NCNT-AW originated from a synergy of surface defects and N-dopants.Specifically,surface defects promoted the anchoring of Cu O nanoparticles on N-containing sites and,thereby,enabled efficient electron transfer from N to Cu O,increasing significantly the fraction of SCR-active Cu^(+)sites in the catalyst.This study puts forward a new idea for manipulating and utilizing the interplay of defects and N-dopants on carbon surfaces to fabricate Cu^(+)-rich Cu catalysts for efficient abatement of slip NH_(3)emissions via selective oxidation.
基金supported by the National Natural Science Foundation of China (No.21976058)the Natural Science Foundation of Guangdong Province (No.2023A1515011682)+3 种基金the Fundamental Research Funds for the Central Universities (No.2022ZYGXZR018)the National Engineering Laboratory for Mobile Source Emission Control Technology (No.NELMS2020A10)the funding from the Pearl River Talent Recruitment Program of Guangdong Province (No.2019QN01L170)the Innovation & Entrepreneurship Talent Program of Shaoguan City。
文摘Palladium-exchanged chabazite(Pd-CHA) zeolites as passive NO_x adsorbers(PNAs) enable efficient purification of nitrogen oxides(NO_x) in cold-start diesel exhausts. Their commercial application, however,is limited by the lack of facile preparation method. Here, high-performance CHA-type Pd-SAPO-34 zeolite was synthesized by a modified solid-state ion exchange(SSIE) method using PdO as Pd precursor,and demonstrated superior PNA performance as compared to Pd-SAPO-34 prepared by conventional wetchemistry strategies. Structural characterization using Raman spectroscopy and X-ray diffraction revealed that the SSIE method avoided water-induced damage to the zeolite framework during Pd loading. Mechanistic investigations on the SSIE process by in situ infrared spectroscopy and X-ray photoelectron spectroscopy disclosed that, while PdO precursor was mainly converted to Pd^(2+) cations coordinated to the zeolite framework by consuming the-OH groups of the zeolite, a portion of PdO could also undergo thermal decomposition to form highly dispersed Pd~0 clusters in the pore channels. This simplified and scalable SSIE method paves a new way for the cost-effective synthesis of defect-free high-performance Pd-SAPO-34 zeolites as PNA catalysts.
基金Key Technology Project of China Southern Power Grid,Grant/Award Number:080045KK52190021。
文摘The buffer layer defects of high‐voltage crosslinked polyethylene(XLPE)cable occur frequently,which makes the detection method become the focus to be studied.Here,the broadband impedance detection technology for the buffer layer defects of high‐voltage XLPE cables with corrugated aluminium sheath is investigated.There are nine cable samples,including new and defective ones.Some of the defective cables are artificial,and the other is retired cables.The influence of wiring mode,the circumferential relative position of electrodes,cable length,artificial white powder,artificial damp,and retired defective cables on the impedance spectrum is studied.It is found that the wiring mode of the insulation shield/aluminium sheath at the end of the cable can effectively detect the buffer layer defects.And the broadband impedance amplitude spectrum of the buffer layer in defective cable,measuring at various circumferential relative positions,is obviously different.When there are white powders,air gaps,or ablation in the buffer layer,the broadband impedance spectrum(BIS)will increase by several times.When the buffer layer is damped,the BIS will reduce.The research here provides theoretical support and technical methods for the buffer layer defects of XLPE cable with corrugated aluminium sheath.
基金supported by Science and Technology Planning Project of Guangdong Province China (No.2015B0202236002)the National Natural Science Foundation of China (Nos.21401200,51108187,51672273,B5151050)+2 种基金the National Key R & D Plan (No.2017YFC0211503)the Open Research Fund of State Key Laboratory of Multi-phase Complex Systems (No.MPCS-2017-D-06)the Guangdong Natural Science Foundation (No.2016A030311003)
文摘Herein, we reported the synthesis of well-defined Co_3O_4 nanoarrays(NAs) supported on a monolithic three-dimensional macroporous nickel(Ni) foam substrate for use in highefficiency CO oxidation. The monolithic Co_3O_4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time,solvent polarity and deposition agent, these Co_3O_4 NAs catalysts exhibited various novel morphologies(single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co_3O_4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity(GHSV) 10,000 hr^(-1) and 150°C with longterm stability. Compared with the other Co_3O_4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites(Co^(3+)/Co^(2+)= 1.26).
基金financially supported by the China Postdoctoral Science Foundation(2016M592496)National Natural Science Foundation of China(Nos.91645119,21207039,U1201231,51378218,51108187 and 50978103)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.2017BQ053 and 2017BQ055)Natural Science Foundation of Guangdong Province,China(Grant No.2014A030310431)Guangzhou Science and Technology Plan(201607010095)
文摘A modified Hummer's method was adopted for the synthesis of graphene oxide(GO) and reduced graphene oxide(rGO). It was revealed that the modified method is effective for the production of GO and rGO from graphite. Transmission electron microscopy(TEM) images of GO and rGO showed a sheet-like morphology. Because of the presence of oxygenated functional groups on the carbon surface, the interlayer spacing of the prepared GO was higher than that of rGO. The presence of /OH and CO groups in the Fourier transform infrared spectra(FTIR) spectrum and G-mode and 2D-mode in Raman spectra confirmed the synthesis of GO and rGO. rGO(292.6 m2/g) showed higher surface area than that of GO(236.4 m2/g). The prepared rGO was used as an adsorbent for benzene and toluene(model pollutants of volatile organic compounds(VOCs)) under dynamic adsorption/desorption conditions. rGO showed higher adsorption capacity and breakthrough times than GO. The adsorption capacity of rGO for benzene and toluene was 276.4 and 304.4 mg/g, respectively.Desorption experiments showed that the spent rGO can be successfully regenerated by heating at 150.0℃. Its excellent adsorption/desorption performance for benzene and toluene makes rGO a potential adsorbent for VOC adsorption.
基金funded by the National Natural Science Foundation of China (Nos. 50708021, 51108187)the Research Fund Program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University, No. 2013K0007)Guangdong Provincial Key Laboratory of Atmospheric environment and Pollution Control (No. 2011A060901011)
文摘Characteristics of toluene decomposition and formation of nitrogen oxide(NOx) by-products were investigated in a dielectric barrier discharge(DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide(Mn Ox), iron oxide(Fe Ox), cobalt oxide(Co Ox) and copper oxide(Cu O), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density(SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the Cu O catalyst showed the best performance in NOx suppression. The Mn Ox catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.
基金Project supported by the National Natural Science Foundation of China(51878293)the National Key Research and Development Plan(2018YFB0605200)China Postdoctoral Science Foundation(2020M682715)。
文摘Metal organic frameworks(MOFs)derivatives represented by quasi-MOFs have excellent physical and chemical properties and can be applied for the catalytic combustion of volatile organic compounds(VOCs).In this work,Pd/quasi-Ce-BTC synthesized by simple one-step Npyrolysis was applied to the oxidation of toluene,showing excellent toluene catalytic activity(T_(90)=175℃,30000 mL/(g·h)).Microscopic analyses indicate the formation and interaction of a carbon matrix composite quasi-MOF structure interface.The results show that the amorphous carbon matrix formed during the partial pyrolysis of Ce-BTC significantly improves the adsorption and activation capacity of toluene in the reaction,and constructs a reductive system to maintain high concentrations of Ce^(3+)and Pd^(0),which can facilitate the activation and utilization of oxygen in reaction.Quasi in-situ XPS proves that carbon matrix is indirectly involved in the activation and storage of oxygen,and Pd^(0)is the crucial active site for the activation of oxygen.Stability and water resistance tests display good stability of Pd/quasi-Ce-BTC.This work provides a potential method for designing quasi-MOF catalysts towards VOCs effective abatement.
基金supported by the China Postdoctoral Science Foundation(Grant No.2018M642627)the National Natural Science Foundation of China(Grant No.51907095)+1 种基金the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2019BEE036)the National Engineering Laboratory for Ultra High Voltage Engineering Technology(Grant No.NEL201802).
文摘As an indispensable part of high-voltage direct current(HVDC)cable,the semiconductive shielding layer plays the role of uniforming electric field in the cable.However,cable shielding materials>35 kV mainly rely on foreign imports in China,which belongs to the technical weak issues in the field of electrical materials.At present,there are few systematic reports on semiconductive shielding material of HVDC cable.In the work,the mechanisms of charge conduction and thermal conduction of semiconductive material have been introduced.Effect of raw material,carbon black content and the second conductive filler on the resistance characteristics of the semiconductive layer,the charge accumulation characteristics of the insulating layer and the interface characteristics have been studied.A kind of semiconductive layer as a high voltage terminal charge emission method has been proposed to study charge emission from the semiconducting layer to the insulation layer.This work can provide theoretical guidance for the research of semiconductive shielding materials.
基金the Science and Technology Project of China Southern Power Grid(no.ZBKJXM20170090).
文摘As an environmental friendly insulating medium,C_(4)F_(7)N has received extensive attention in the past two years.In this study,the partial discharge(PD)and breakdown characteristics of C_(4)F_(7)N/CO_(2)gas mixture were investigated using the gas insulation performance test platform.The influence of gas pressure and mixing ratio on the PD initial voltage(PDIV)and breakdown voltage of C_(4)F_(7)N/CO_(2)gas mixture in different electric fields was tested.It was found that the PDIV and breakdown voltage of gas mixture with 2-8%C_(4)F_(7)N in the highly non-uniform field showed a linear saturation increasing trend with the change of gas pressure and mixing ratio.The breakdown voltage of gas mixture increases linearly with gas pressure in the quasi-uniform electric field.The relative breakdown voltage of gas mixture in the highly non-uniform field under high-pressure conditions is inferior to those of low-pressure conditions.The C_(4)F_(7)N/CO_(2)gas mixture containing 2-8%C_(4)F_(7)N is sensitive to the non-uniformity of electric field.According to the PD and breakdown tests results,C_(4)F_(7)N/CO_(2)gas mixture with 2-8%C_(4)F_(7)N has the potential to replace SF6 using in gas-insulated equipment.
基金financially supported by the China Postdoctoral Science Foundation(No.2018M643090)the National Natural Science Foundation of China(No.52000077)+3 种基金the National Key Research and Development Project of Research(No.2017YFC0212805)the National Natural Science Foundation of China(No.51878292)the Natural Science Foundation of Guangdong Province,China(No.2015B020236002)the China Postdoctoral Science Foundation(No.2020M682715).
文摘A facile hydrothermal method was applied to gain stably and highly efficient CuO-CeO_(2)(denoted as Cu1Ce2)catalyst for toluene oxidation.The changes of surface and inter properties on Cu1Ce2 were investigated comparing with pure CeO_(2)and pure CuO.The formation of Cu-Ce interface promotes the electron transfer between Cu and Ce through Cu^(2+)+Ce^(3+)↔Cu^(+)+Ce^(4+)and leads to high redox properties and mobility of oxygen species.Thus,the Cu1Ce2 catalyst makes up the shortcoming of CeO_(2)and CuO and achieved high catalytic performance with T_(50)=234°C and T_(99)=250°C(the temperature at which 50%and 90%C_(7)H_(8)conversion is obtained,respectively)for toluene oxidation.Different reaction steps and intermediates for toluene oxidation over Cu1Ce2,CeO_(2)and CuO were detected by in situ DRIFTS,the fast benzyl species conversion and preferential transformation of benzoates into carbonates through C=C breaking over Cu1Ce2 should accelerate the reaction.
基金financially supported by the Scientific Research Project of Guangzhou City(No.201804020026)the National Nat-ural Science Foundation of China(Nos.51878293,21777047)+1 种基金the National Key Research and Development Program of China(No.2018YFB0605200)the Natural Science Foundation of Guang-dong Province(No.2017B090901049).
文摘The temperature of waste gas in refuse transfer station,airport smoking area,and RTO terminal is low,which needs deep oxidation.Catalytic ozonation is one of the most effective treatment techniques in these scenarios.In this study,we reported that catalysts were modified under the condition of mag-netic field to simulate the low temperature dynamic conditions of low concentration toluene for catalytic ozonation.This paper aims to explore the relationship between oxygen vacancy and active oxygen species,and the specific pathways of toluene oxidation.The study found that citric acid can enhance the syner-gistic effect between Mn and Ce,and promote the generation of oxygen vacancies.The surface molecule adsorption oxygen is more conducive to catalytic oxidation than subsurface atom adsorption oxygen.Fi-nally,we proposed the main pathways of toluene in this reaction system,which runs through the whole process of the reaction.
基金financially supported by the Research Funds of the Guilin University of Technology(No.GUTQDJJ202041)Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control(No.Guikeneng 2001K002)+2 种基金National Natural Science Foundation of China(Nos.51978189,51878292)National Key R&D Program of China(No.2017YFC0211503)China Postdoctoral Science Foundation(No.2020M683629XB)。
文摘Herein,a facile glycol reduction route is successful employed to synthesize bimetallic Pt Ag alloys with homogeneous distribution of sizes and elements.Experimental studies reveal that the ultrafine Pt Ag alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO_(2)microsphere,which remarkably enhances the catalytic performances for CO oxidation.Importantly,quasi in-situ X-ray photoelectron spectroscopy(XPS)result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by CO and O_(2)molecules,and the oxygen vacancy sites could be replenished and excited by gas-phase O_(2).
基金financially supported by Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302013)the Natural Science Foundation for Distinguished Young Scientists of Guangdong Province(No.2020B1515020015)+1 种基金Pearl River S&T Nova Program of Guangzhou(No.201806010069)。
文摘Ceria is widely used as a catalyst for soot combustion,but effects of Zr substitution on the reaction mechanism is ambiguous.The present work elucidates effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria.The nanostructured CeO_(2),Ce_(0.92)Zr_(0.08)O_(2),and Ce_(0.84)Zr_(0.16)O_(2)composed of 5-6 nm crystallites display T_(m-CO2)(the temperature at maximum CO_2 yield)at 383,355,and 375℃under 10 vol.%O_(2)/N_(2),respectively.The size of agglomerate decreases from 165.5 to 51.9-57.3 nm,which is beneficial for the sootceria contact.Moreover,Zr increases the amount of surface oxygen vacancies,generating more active oxygen(O_(2)^-and O^(-))for soot oxidation.Thus,the activities of Ce_(0.92)Zr_(0.08)O_(2)and Ce_(0.84)Zr_(0.16)O_(2)in soot combustion are better than that of CeO_(2).Although oxygen vacancies promote the migration of lattice O~(2-),the enriched surface Zr also inhibits the mobility of lattice O^(2-).Therefore,the T_(m-CO2)of Ce_(0.84)Zr_(0.1)6 O_(2)is higher than that of Ce_(0.92)Zr_(0.08)O_(2).Based on reaction kinetic study,soot in direct contact with ceria preferentially decomposes with low activation energy,while the oxidation of isolated soot occurs through diffusion with high activation energy.The obtained findings provide new understanding on the soot combustion over nanoceria.
文摘The authors regret“In the whole text,ppm and mg/L was confusing.As in aqueous phase,1 ppm=1 mg/L,but in gaseous phase,1 ppm=0.001%o.In this paper,in text and figures,the concentration units were ppm,but when calculating the adsorption ca-pacity,the concentration units ppm were mistakenly used as mg/L.As for benzene,1 ppm=3.4871 x 10^-3 mg/L,as for toluene。