The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber ...The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling model.The accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust chamber.Additionally,key parameters related to heat transfer performance were calculated.The results demonstrate that the model is sufficiently accurate to be used as a preliminary design tool.The temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer analysis.In addition,the performance of composite cooling is observed to be superior to regenerative cooling.Increasing the gas film flow rate results in higher cooling efficiency and a lower gas-side wall temperature.Furthermore,the position at which the gas film is introduced greatly impacts the cooling performance.The optimal introduction position for the gas film is determined when the film is introduced from a single row of holes.This optimal introduction position results in a more uniform wall temperature distribution and reduces the peak temperature.Lastly,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall temperature.These results provide a basis for the design of gas film/regenerative composite cooling systems.展开更多
Electrocatalytic CO_(2)reduction(ECR)to produce value-added fuels and chemicals using renewable electricity is an emerging strategy to mitigate global warming and decrease reliance on fossil fuels.Among various ECR pr...Electrocatalytic CO_(2)reduction(ECR)to produce value-added fuels and chemicals using renewable electricity is an emerging strategy to mitigate global warming and decrease reliance on fossil fuels.Among various ECR products,liquid oxygenates(Oxys)are especially attractive due to their high energy density,high safety and transportability that could be adapted to the existing infrastructure and transportation system.However,efficiently generating these highly reduced oxygen-containing products by ECR remains challenging due to the complexity of coupled proton and electron transfer processes.In recent years,in-depth studies of reaction mechanisms have advanced the design of catalysts and the regulation of reaction systems for ECR to produce Oxys,Here,by focusing on the production of typical Oxys,such as methanol,acetic acid,ethanol,acetone,n-propanol,and isopropanol,we outline various reaction paths and key intermediates for the electrochemical conversion of CO_(2)into these target products.We also summarize the current research status and recent advances in catalysts based on their elemental composition,and consider recent studies on the change of catalyst geometry and electronic structure,as well as the optimization of reaction systems to increase ECR performance.Finally,we analyze the challenges in the field of ECR to Oxys and provide an outlook on future directions for high-efficiency catalyst prediction and design,as well as the development of advanced reaction systems.展开更多
The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled elec...The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts.展开更多
Natural gas is widely regarded as an efficient,relatively clean,and economically viable energy source.Its safe operation and continuous supply through pipeline infrastructure has led to its prominence in the energy se...Natural gas is widely regarded as an efficient,relatively clean,and economically viable energy source.Its safe operation and continuous supply through pipeline infrastructure has led to its prominence in the energy sector.Methanol plays an important role in the natural gas industry,typically serving as a solvent or hydrate inhibitor.Therefore,the accurate estimation of thermodynamic properties for methane/methanol binary is extremely important to optimise the operating parameter,maximise the dehydration effect,and reduce the cost.As the Helmholtz energy equation of state is expected to offer high accuracy in predicting the vapour-liquid equilibrium of methane/methanol binary,four reducing parameters were derived based on collected experimental data.Additionally,the sensitivities of various reducing parameter combinations were simultaneously investigated.The results demonstrated a strong agreement between predicted fractions and experimental data,with the UMADs(uncertainty-weighted mean absolute deviation)of 3.484 and 0.665 for liquid and vapour phases,respectively.Meanwhile,it is deemed“very likely”,“likely”,and“unlikely”to achieve acceptable prediction for 3-parameter optimisation,2-parameter optimisation and,1-parameter optimisation,respectively.展开更多
The development of highly active functionalized ionic liquids(ILs)as both extractants and catalysts for use in achieving deep desulfurization continues to pose challenges.In this study,a highly efficient oxidative des...The development of highly active functionalized ionic liquids(ILs)as both extractants and catalysts for use in achieving deep desulfurization continues to pose challenges.In this study,a highly efficient oxidative desulfurization system was constructed,composed of dual-acidic ionic liquids(DILs)and H_(2)O_(2)-AcOH.The investigation results of four DILs prepared from different metal chlorides([HSO_(3)C_(3)NEt_(3)]Cl-MnCl_(n),MnCl_(n)=AlCl_(3),ZnCl_(2),CuCl_(2),FeCl_(3))in oxidative desulfurization showed that[HSO_(3)C_(3)NEt_(3)]Cl-AlCl_(3)had an outstanding catalytic effect and significantly promoted the oxidation of sulfides.With a 0.2 g[HSO_(3)C_(3)NEt_(3)]Cl-AlCl_(3),the removal rate of dibenzothiophene(DBT)reached 100%in 10 mL model oil under mild conditions at 55℃for 20 min.The key is its ability to induce the dismutation of su-peroxide anions(·O_(2)^(-)),which facilitates the generation of singlet oxygen(1 O_(2)).The efficient oxidation of DBT is accomplished through a predominantly^(1)O_(2)-mediated_(n)on-radical mechanism.[HSO_(3)C_(3)NEt_(3)]Cl-AlCl_(3)serves as a favorable medium for contact to be made between^(1)O_(2)and sulfides,which indicates an efficient catalytic-adsorption synergy.展开更多
Developing efficient and stable non-precious metal catalysts is essential for replacing platinum-based catalysts in polymer electrolyte membrane fuel cells(PEMFCs).The transition metal and nitrogen co-doped carbon ele...Developing efficient and stable non-precious metal catalysts is essential for replacing platinum-based catalysts in polymer electrolyte membrane fuel cells(PEMFCs).The transition metal and nitrogen co-doped carbon electrocatalyst(M-N-C)is considered an effective alternative to precious metal catalysts.However,its relatively poor performance in acidic environments has always been a problem plaguing its practical application in PEMFCs.This study presents a sequential deposition methodology for constructing a composite catalytic system of Fe-N-C and ionic liquid(IL),which exhibits improved performance at both half-cell and membrane electrode assembly scales.The presence of IL significantly inhibits H_(2)O_(2)production,preferentially promoting the 4e–O_(2)reduction reaction,resulting in improved electrocatalytic activity and stability.Additionally,the enhanced PEMFC performance of IL containing electrodes is a direct result of the improved ionic and reactant accessibility of the pore confined Fe-N-C catalysts where the IL minimizes local resistive transport losses.This study establishes a strategic foundation for the practical utilization of non-precious metal catalysts in PEMFCs and other energy converting technologies.展开更多
Development of clean desulfurization process that combines both efficient and environmentally friendly remains a significant challenge for diesel production.The photocatalytic oxidation desulfurization technology is r...Development of clean desulfurization process that combines both efficient and environmentally friendly remains a significant challenge for diesel production.The photocatalytic oxidation desulfurization technology is regarded as a promising process depending on the superior electron transfer and visible light utilization of photocatalyst.Herein,the nonstoichiometry MoO_(3-x)with outstanding photoresponse ability is prepared and modified by imidazole-based ionic liquid[C_(12)mim]Cl to upgrade electronic structure.The interface H-bonding between MoO_(3-x)and[C_(12)mim]Cl regard as electronic transfer channel and the recombination of e^(-)-h^(+)pairs is effectively inhibited with the modification of[C_(12)mim]Cl.Deep desulfurization rate of 96.6%can be reached within 60 min and the MoO_(3-x)/[C_(12)mim]Cl(MoC_(12))photocatalyst demonstrated outstanding cyclic stability within 7 cycles in an extraction coupled photocatalytic oxidation desulfurization(ECPODS)system.The study provides a new perspective on enhancing photocatalytic desulfurization through defect engineering and surface modification.展开更多
The large-scale commercialization of proton exchange membrane fuel cells(PEMFCs)has been hindered by the high demand of platinum(Pt)in the cathode due to the sluggish kinetics of the oxygen reduction reaction.Reducing...The large-scale commercialization of proton exchange membrane fuel cells(PEMFCs)has been hindered by the high demand of platinum(Pt)in the cathode due to the sluggish kinetics of the oxygen reduction reaction.Reducing the amount of Pt would worsen the problems caused by the adsorption of perfluorinated sulfonic acid(PFSA)ionomers to Pt via the side chains,namely,blocking the active sites of Pt and inducing densely packed layers of fluorocarbon backbones on Pt surface to obstruct local O_(2)transport at the Pt/PFSA interfaces.This work aims at optimizing the Pt/ionomer interface to mitigate the sulfonate adsorption and in the meantime to reduce the local O_(2)transport resistance(R_(local)),by using a porous composite of 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquid(IL)modified MOF-808(BMImHSO_(4)@MOF-808)as additive in cathodic catalyst layer(CCL).Through detailed physical,spectroscopic and electrochemical characterizations,we demonstrate a three-fold optimization mechanism of Pt/ionomer interface structure by BMImHSO_(4)@MOF-808:the unsaturated metal sites in MOF-808 effectively inhibit the sulfonate adsorption on Pt through coordination with the sulfonates of PFSA,thereby improving catalyst utilization;the pores in MOF-808 establish efficient transport channels for gaseous oxygen,significantly reducing R_(local);the IL modification layers facilitate the formation of continuous proton transport networks,increasing proton conductivity.The incorporation of BMImHSO_(4)@MOF-808 in a low-Pt CCL(0.1 mg_(Pt)cm^(-2))yields a peak power density of 1.9 W cm^(-2)for PEMFC under H_(2)-O_(2)condition,and ca.20%increase of power density under H_(2)-air condition as compared with conventional CCL,indicating the prospect of IL-MOF composites as an efficient additive to enhance the performance of PEMFCs.展开更多
Direct conversion of methane using a metal-loaded ZSM-5 zeolite prepared viaacidic ion exchange was investigated to elucidate the roles of metal and acidity in the formation ofliquid hydrocarbons. ZSM-5 (SiO_2/Al_2O_3...Direct conversion of methane using a metal-loaded ZSM-5 zeolite prepared viaacidic ion exchange was investigated to elucidate the roles of metal and acidity in the formation ofliquid hydrocarbons. ZSM-5 (SiO_2/Al_2O_3=30) was loaded with different metals (Cr, Cu and Ga)according to the acidic ion-exchange method to produce metal-loaded ZSM-5 zeolite catalysts. XRD,NMR, FT-IR and N_2 adsorption analyses indicated that Cr and Ga species managed to occupy thealuminum positions in the ZSM-5 framework. In addition, Cr species were deposited in the pores ofthe structure. However, Cu oxides were deposited on the surface and in the mesopores of the ZSM-5zeolite. An acidity study using TPD-NH_3, FT-IR, and IR-pyridine analyses revealed that the totalnumber of acid sites and the strengths of the Broensted and Lewis acid sites were significantlydifferent after the acidic ion exchange treatment. Cu loaded HZSM-5 is a potential catalyst fordirect conversion of methane to liquid hydrocarbons. The successful production of gasoline via thedirect conversion of methane depends on the amount of aluminum in the zeolite framework and thestrength of the Broensted acid sites.展开更多
For direct gas to liquid（GTL）,a novel process producing energy sources for methane dehydroaromatization is needed.Supporting MoO3 on H-MFI zeolite shows the high catalytic capacity and a selective activity for dehyd...For direct gas to liquid（GTL）,a novel process producing energy sources for methane dehydroaromatization is needed.Supporting MoO3 on H-MFI zeolite shows the high catalytic capacity and a selective activity for dehydroaromatization of methane to benzene at 973 K in a fixed bed reactor.On the other hand,deactivation by coke on the active sites in all the catalysts is formed during the reaction.H2 co-feed suppressed the deactivation,which is probably due to the decrease in coking amount.Mo K-edge X-ray absorption fine structure（XAFS） results showed the formation of dispersed Mo2C species with low crystallinity after dehydroaromatization.Mo LIII-edge XANES（X-ray absorption near-edge structure） indicated the formation of active Mo species including Mo2C and Mo-oxycarbide（MoOxCy）,where the redox state should be independent in the absence/presence of H2.It is concluded that Mo-oxycarbide species act as highly active species,and their stability affected the durable activity in the presence of H2.展开更多
A reversible storage-release process switched by a temperature difference of 10 ℃ around room temperature can be realized. This fast, recyclable, energy efficient, low cost and green system within a wide range of tem...A reversible storage-release process switched by a temperature difference of 10 ℃ around room temperature can be realized. This fast, recyclable, energy efficient, low cost and green system within a wide range of temperature and pressure is reported here for the first time. The system is believed to open up a new route for the storage and homogeneous utilization of methane.展开更多
Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SE...Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SEM)are employed to visualize and quantify morphological evolution characteristics of fractures in coal after LN2 thermal shocking treatments.LN2 thermal shocking leads to a denser fracture network than its original state with coal porosity growth rate increasing up to 183.3%.The surface porosity of theμCT scanned layers inside the coal specimen is influenced by LN2 thermal shocking which rises from 18.76%to 215.11%,illustrating the deformation heterogeneity of coal after LN2 thermal shocking.The cracking effect of LN2 thermal shocking on the surface of low porosity is generally more effective than that of high surface porosity,indicating the applicability of LN2 thermal shocking on low-permeability CBM reservoir stimulation.The characteristics of SEM scanned coal matrix in the coal powder and the coal block after the LN2 thermal shocking presented a large amount of deep and shallow progressive scratch layers,fracture variation diversity(i.e.extension,propagation,connectivity,irregularity)on the surface of the coal block and these were the main reasons leading to the decrease of the uniaxial compressive strength of the coal specimen.展开更多
Pd-containing ionic liquid （IL） 1-hexyl-3-methylimidazolium tetrafluoroborate （C6MIMBF4） immobilized on γ-Al2O3 （Pd-IL/γ-Al2O3） was prepared and characterized by Fourier transform infrared spectroscopy （FTIR...Pd-containing ionic liquid （IL） 1-hexyl-3-methylimidazolium tetrafluoroborate （C6MIMBF4） immobilized on γ-Al2O3 （Pd-IL/γ-Al2O3） was prepared and characterized by Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM） and Brunauer-Emmett- Teller （BET） analysis. The influences of C6MIMBF4 loading and Pd on methane conversion to C2 hydrocarbons under cold plasma were investigated. FTIR and SEM analyses indicated that C6MIMBF4 had been successfully immobilized on γ-Al2O3 and the C6MIMBF4 showed excellent stability under cold plasma. The results of BET and methane conversion showed that with the increase in immobilization amount of C6MIMBF4 onto γ-Al2O3, the specific surface area and pore volume of IL/γ-Al2O3 decreased, while the selectivity and yield of C2 hydrocarbons increased. The selectivity of C2 hydrocarbons was 94.6% when the loading of C6MIMBF4 was 40%, and the percentage of C2H4 in C2 hydrocarbons was as high as 64% when using Pd-IL/γ-Al2O3 as a catalyst with no conventional thermal reduction treatment. Optical emission spectra （OES） from the cold plasma reactor during methane conversion were also studied. The results indicated that the intensity of the C2, CH, H, and C active species from methane and hydrogen decomposition increased when IL/γ-Al2O3 or Pd-IL/γ-Al2O3 was introduced into the plasma system. Based on the analyses of the gas product and OES spectra, it can be concluded that the surface catalyzed reactions between plasma and ionic liquid were very important for the reduction of Pd2＋ and the formation of C2H4.展开更多
Metal containing ZSM-5 can produce higher hydrocarbons in methane oxidation. Many researchers have studied the applicability of HZSM-5 and modify ZSM-5 for methane conversion to liquid hydrocarbons, but their research...Metal containing ZSM-5 can produce higher hydrocarbons in methane oxidation. Many researchers have studied the applicability of HZSM-5 and modify ZSM-5 for methane conversion to liquid hydrocarbons, but their research results still lead to low conversion, low selectivity and low heat resistance. The modified HZSM-5, by loading with tungsten （W）, could enhance its heat resistant performance, and the high reaction temperature （800 ℃） did not lead to a loss of the W component by sublimation. The loading of HZSM-5 with tungsten and copper （Cu） resulted in an increment in the methane conversion as well as CO2 and C5＋ selectivities. In contrast, CO, C2-3 and H2O selectivities were reduced. The process of converting methane to liquid hydrocarbons （C5＋） was dependent on the metal surface area and the acidity of the zeolite. High methane conversion and C5＋ selectivity, and low H20 selectivity are obtained over W/3.0Cu/HZSM.展开更多
The conversion of methane to liquid fuels is still in the development process. The modified HZSM-5 by loading with Tungsten （W） enhanced its heat resistant performance, and the high reaction temperature （800℃） di...The conversion of methane to liquid fuels is still in the development process. The modified HZSM-5 by loading with Tungsten （W） enhanced its heat resistant performance, and the high reaction temperature （800℃） did not lead to the loss of W component by sublimation. The loading of ZSM-5 with Tungsten and Copper （Cu） resulted in an increment in the methane conversion, CO2, and C5＋ selectivities. The high methane conversion and C5＋ selectivity, and low H2O selectivity are obtained by using W/3.0Cu/ZSM-5. The optimization of methane conversion over 3.0 W/3.0Cu/ZSM-5 under different temperature and oxygen concentration using response surface methodology （RSM） are studied. The optimum point for methane conversion is 19% when temperature is 753 ℃, and oxygen concentration is 12%. The highest C5＋ selectivity is 27% when temperature is 751 ℃. and oxwen concentration is 11%.展开更多
Promoted and mediated by an ionic liquid-[bmim][BF4], fused pyrans or arylbis（4-hydroxy-6-methyl-2-oxo-2H-pyran-3- yl）methanes were efficiently and selectively prepared from the reaction of aldehyde and 4-hydroxy-6-...Promoted and mediated by an ionic liquid-[bmim][BF4], fused pyrans or arylbis（4-hydroxy-6-methyl-2-oxo-2H-pyran-3- yl）methanes were efficiently and selectively prepared from the reaction of aldehyde and 4-hydroxy-6-methyl-2-oxo-pyran with or without acetic anhydride. By using these novel procedures, pyrimidine nucleoside-fused pyran and arylbis（pyranon-3-yl）methane hybrids with potential biological activities were constructed.展开更多
Efficient electrophilic substitution reaction of indoles with various aromatic aldehydes were carried out with a catalytic amount of sodium hydrogensulfate monohydrate （NaHSO4·H20） in ionic liquid n-butylpyridi...Efficient electrophilic substitution reaction of indoles with various aromatic aldehydes were carried out with a catalytic amount of sodium hydrogensulfate monohydrate （NaHSO4·H20） in ionic liquid n-butylpyridinium tetrafluoroborate （[Bpy]BF4） to afford the corresponding bi（indolyl）methanes in excellent yields. The notable advantages of this protocol in terms of low cost of catalyst and ionic liquid, mild conditions, simple operation, short reaction time, high yields and recycling of the ionic liquid.展开更多
Methane chemistry is one of the“Holy Grails of catalysis”.It is highly desirable but challenge to transform methane into value-added chemicals,because of its high C-H bonding energy(435 kJ/mol),lack ofπbonding or u...Methane chemistry is one of the“Holy Grails of catalysis”.It is highly desirable but challenge to transform methane into value-added chemicals,because of its high C-H bonding energy(435 kJ/mol),lack ofπbonding or unpaired electrons.Currently,commercial methane conversion is usually carried out in harsh conditions with enormous energy input.Photocatalytic partial oxidation of methane to liquid oxygenates(PPOMO)is a future-oriented technology towards realizing high efficiency and high selectivity under mild conditions.The selection of oxidant is crucial to the PPOMO performance.Hence,attentions are paid to the research progress of PPOMO with various oxidants(O_(2),H_(2)O,H_(2)O_(2)and other oxidants).Moreover,the activation of the selected oxidants is also highly emphasized.Meanwhile,we summarized the methane activation mechanisms focusing on the C-H bond that was broken mainly by·OH radical,O-specie or photogenerated hole(h+).Finally,the challenges and prospects in this subject are briefly discussed.展开更多
Hydrogen production from electrochemical water splitting is a promising strategy to generate green energy,which requires the development of efficient and stable electrocatalysts for the hydrogen evolution reaction and...Hydrogen production from electrochemical water splitting is a promising strategy to generate green energy,which requires the development of efficient and stable electrocatalysts for the hydrogen evolution reaction and the oxygen evolution reaction(HER and OER).Ionic liquids(ILs)or poly(ionic liquids)(PILs),containing heteroatoms,metal-based anions,and various structures,have been frequently involved as precursors to prepare electrocatalysts for water splitting.Moreover,ILs/PILs possess high conductivity,wide electrochemical windows,and high thermal and chemical stability,which can be directly applied in the electrocatalysis process with high durability.In this review,we focus on the studies of ILs/PILs-derived electrocatalysts for HER and OER,where ILs/PILs are applied as heteroatom dopants and metal precursors to prepare catalysts or are directly utilized as the electrocatalysts.Due to those attractive properties,IL/PIL-derived electrocatalysts exhibit excellent performance for electrochemical water splitting.All these accomplishments and developments are systematically summarized and thoughtfully discussed.Then,the overall perspectives for the current challenges and future developments of ILs/PILs-derived electrocatalysts are provided.展开更多
基金supported by the National Science Fund Project(No.2019-JCJQ-ZQ-019)the Innovative Research Group Project of National Natural Science Foundation of China(No.T2221002).
文摘The thermal protection of rocket engines is a crucial aspect of rocket engine design.In this paper,the gas film/regenerative composite cooling of the liquid oxygen/liquid methane(LOX/LCH4)rocket engine thrust chamber was investigated.A gas film/regenerative composite cooling model was developed based on the Grisson gas film cooling efficiency formula and the one-dimensional regenerative cooling model.The accuracy of the model was validated through experiments conducted on a 6 kg/s level gas film/regenerative composite cooling thrust chamber.Additionally,key parameters related to heat transfer performance were calculated.The results demonstrate that the model is sufficiently accurate to be used as a preliminary design tool.The temperature rise error of the coolant,when compared with the experimental results,was found to be less than 10%.Although the pressure drop error is relatively large,the calculated results still provide valuable guidance for heat transfer analysis.In addition,the performance of composite cooling is observed to be superior to regenerative cooling.Increasing the gas film flow rate results in higher cooling efficiency and a lower gas-side wall temperature.Furthermore,the position at which the gas film is introduced greatly impacts the cooling performance.The optimal introduction position for the gas film is determined when the film is introduced from a single row of holes.This optimal introduction position results in a more uniform wall temperature distribution and reduces the peak temperature.Lastly,it is observed that a double row of holes,when compared to a single row of holes,enhances the cooling effect in the superposition area of the gas film and further lowers the gas-side wall temperature.These results provide a basis for the design of gas film/regenerative composite cooling systems.
基金financial supports from the National Natural Science Foundation of China(52201237)the Talent Introduction Project of Chinese Academy of Sciences(E344011)+4 种基金the Shenzhen High Level Talent Team Project(KQTD2022110109364705)the Joint Research Project of China Merchants Group and SIAT(E2Z1521)the Cross Institute Joint Research Youth Team Project of SIAT(E25427)National Natural Science Foundation of China(52402136)the China Postdoctoral Science Foundation(E325281005)。
文摘Electrocatalytic CO_(2)reduction(ECR)to produce value-added fuels and chemicals using renewable electricity is an emerging strategy to mitigate global warming and decrease reliance on fossil fuels.Among various ECR products,liquid oxygenates(Oxys)are especially attractive due to their high energy density,high safety and transportability that could be adapted to the existing infrastructure and transportation system.However,efficiently generating these highly reduced oxygen-containing products by ECR remains challenging due to the complexity of coupled proton and electron transfer processes.In recent years,in-depth studies of reaction mechanisms have advanced the design of catalysts and the regulation of reaction systems for ECR to produce Oxys,Here,by focusing on the production of typical Oxys,such as methanol,acetic acid,ethanol,acetone,n-propanol,and isopropanol,we outline various reaction paths and key intermediates for the electrochemical conversion of CO_(2)into these target products.We also summarize the current research status and recent advances in catalysts based on their elemental composition,and consider recent studies on the change of catalyst geometry and electronic structure,as well as the optimization of reaction systems to increase ECR performance.Finally,we analyze the challenges in the field of ECR to Oxys and provide an outlook on future directions for high-efficiency catalyst prediction and design,as well as the development of advanced reaction systems.
基金supported by the National Natural Science Foundation of China(22209040,22202063).
文摘The development of highly active catalyst in pH-neutral media for oxygen evolution reaction(OER)is critical in the field of renewable energy storage and conversion.Nevertheless,the slow kinetics of proton-coupled electron transfer(PCET)hinders the overall OER efficiency.Herein,we report an ionic liquid(IL)modified CoSn(OH)_(6)nanocubes(denoted as CoS-n(OH)_(6)-IL),which could be prepared through a facile strategy.The modified IL would not change the structural character-istics of CoSn(OH)_(6),but could effectively regulate the local proton activity near the active sites.The CoSn(OH)_(6)-IL exhibited higher intrinsic OER performances than the pristine CoSn(OH)_(6)in neutral media.For example,the current density of CoS-n(OH)_(6)-IL at 1.8 V versus reversible hydrogen electrode(RHE)was about 4 times higher than that of CoSn(OH)_(6).According to the pH-dependent kinetic investigations,operando electrochemical impedance spectroscopic,chemical probe tests,and deuterium kinetic isotope effects,the interfacial layer of IL could be utilized as a proton transfer mediator to promote the proton transfer,which enhances the surface coverage of OER intermediates and reduces the activation barrier.Consequent-ly,the sluggish OER kinetics would be efficiently accelerated.This study provides a facile and effective strategy to facilitate the PCET processes and is beneficial to guide the rational design of OER electrocatalysts.
基金supported financially by the National Natural Science Foundation of China(52202434)the National Natural Science Foundation of Ningbo(2023J275).
文摘Natural gas is widely regarded as an efficient,relatively clean,and economically viable energy source.Its safe operation and continuous supply through pipeline infrastructure has led to its prominence in the energy sector.Methanol plays an important role in the natural gas industry,typically serving as a solvent or hydrate inhibitor.Therefore,the accurate estimation of thermodynamic properties for methane/methanol binary is extremely important to optimise the operating parameter,maximise the dehydration effect,and reduce the cost.As the Helmholtz energy equation of state is expected to offer high accuracy in predicting the vapour-liquid equilibrium of methane/methanol binary,four reducing parameters were derived based on collected experimental data.Additionally,the sensitivities of various reducing parameter combinations were simultaneously investigated.The results demonstrated a strong agreement between predicted fractions and experimental data,with the UMADs(uncertainty-weighted mean absolute deviation)of 3.484 and 0.665 for liquid and vapour phases,respectively.Meanwhile,it is deemed“very likely”,“likely”,and“unlikely”to achieve acceptable prediction for 3-parameter optimisation,2-parameter optimisation and,1-parameter optimisation,respectively.
基金support provided by South Africa National Research Foundation(UID 95983,113648,137947)Foundation for Innovative Research Groups of the Natural Science Foundation of Hebei Province(no.B2021208005).
文摘The development of highly active functionalized ionic liquids(ILs)as both extractants and catalysts for use in achieving deep desulfurization continues to pose challenges.In this study,a highly efficient oxidative desulfurization system was constructed,composed of dual-acidic ionic liquids(DILs)and H_(2)O_(2)-AcOH.The investigation results of four DILs prepared from different metal chlorides([HSO_(3)C_(3)NEt_(3)]Cl-MnCl_(n),MnCl_(n)=AlCl_(3),ZnCl_(2),CuCl_(2),FeCl_(3))in oxidative desulfurization showed that[HSO_(3)C_(3)NEt_(3)]Cl-AlCl_(3)had an outstanding catalytic effect and significantly promoted the oxidation of sulfides.With a 0.2 g[HSO_(3)C_(3)NEt_(3)]Cl-AlCl_(3),the removal rate of dibenzothiophene(DBT)reached 100%in 10 mL model oil under mild conditions at 55℃for 20 min.The key is its ability to induce the dismutation of su-peroxide anions(·O_(2)^(-)),which facilitates the generation of singlet oxygen(1 O_(2)).The efficient oxidation of DBT is accomplished through a predominantly^(1)O_(2)-mediated_(n)on-radical mechanism.[HSO_(3)C_(3)NEt_(3)]Cl-AlCl_(3)serves as a favorable medium for contact to be made between^(1)O_(2)and sulfides,which indicates an efficient catalytic-adsorption synergy.
基金国家自然科学基金(22202124,22208376)山西省科技创新团队专项资金(202304051001023)+3 种基金山西省重点研发计划(202302060301009)山西省国家留学基金委(2023-008,2023-009)山东省自然科学基金(ZR2023LFG005)青岛新能源山东实验室开放项目(QNESL OP 202303).
文摘Developing efficient and stable non-precious metal catalysts is essential for replacing platinum-based catalysts in polymer electrolyte membrane fuel cells(PEMFCs).The transition metal and nitrogen co-doped carbon electrocatalyst(M-N-C)is considered an effective alternative to precious metal catalysts.However,its relatively poor performance in acidic environments has always been a problem plaguing its practical application in PEMFCs.This study presents a sequential deposition methodology for constructing a composite catalytic system of Fe-N-C and ionic liquid(IL),which exhibits improved performance at both half-cell and membrane electrode assembly scales.The presence of IL significantly inhibits H_(2)O_(2)production,preferentially promoting the 4e–O_(2)reduction reaction,resulting in improved electrocatalytic activity and stability.Additionally,the enhanced PEMFC performance of IL containing electrodes is a direct result of the improved ionic and reactant accessibility of the pore confined Fe-N-C catalysts where the IL minimizes local resistive transport losses.This study establishes a strategic foundation for the practical utilization of non-precious metal catalysts in PEMFCs and other energy converting technologies.
基金supports from National Natural Science Foundation of China(Nos.22172066,22378176)supported by State Key Laboratory of Heavy Oil Processing.Supported by Jiangsu Collaborative Innovation Center of TechnologyMaterial of Water Treatment,Suzhou University of Science and Technology.
文摘Development of clean desulfurization process that combines both efficient and environmentally friendly remains a significant challenge for diesel production.The photocatalytic oxidation desulfurization technology is regarded as a promising process depending on the superior electron transfer and visible light utilization of photocatalyst.Herein,the nonstoichiometry MoO_(3-x)with outstanding photoresponse ability is prepared and modified by imidazole-based ionic liquid[C_(12)mim]Cl to upgrade electronic structure.The interface H-bonding between MoO_(3-x)and[C_(12)mim]Cl regard as electronic transfer channel and the recombination of e^(-)-h^(+)pairs is effectively inhibited with the modification of[C_(12)mim]Cl.Deep desulfurization rate of 96.6%can be reached within 60 min and the MoO_(3-x)/[C_(12)mim]Cl(MoC_(12))photocatalyst demonstrated outstanding cyclic stability within 7 cycles in an extraction coupled photocatalytic oxidation desulfurization(ECPODS)system.The study provides a new perspective on enhancing photocatalytic desulfurization through defect engineering and surface modification.
文摘The large-scale commercialization of proton exchange membrane fuel cells(PEMFCs)has been hindered by the high demand of platinum(Pt)in the cathode due to the sluggish kinetics of the oxygen reduction reaction.Reducing the amount of Pt would worsen the problems caused by the adsorption of perfluorinated sulfonic acid(PFSA)ionomers to Pt via the side chains,namely,blocking the active sites of Pt and inducing densely packed layers of fluorocarbon backbones on Pt surface to obstruct local O_(2)transport at the Pt/PFSA interfaces.This work aims at optimizing the Pt/ionomer interface to mitigate the sulfonate adsorption and in the meantime to reduce the local O_(2)transport resistance(R_(local)),by using a porous composite of 1-butyl-3-methylimidazolium hydrogen sulfate ionic liquid(IL)modified MOF-808(BMImHSO_(4)@MOF-808)as additive in cathodic catalyst layer(CCL).Through detailed physical,spectroscopic and electrochemical characterizations,we demonstrate a three-fold optimization mechanism of Pt/ionomer interface structure by BMImHSO_(4)@MOF-808:the unsaturated metal sites in MOF-808 effectively inhibit the sulfonate adsorption on Pt through coordination with the sulfonates of PFSA,thereby improving catalyst utilization;the pores in MOF-808 establish efficient transport channels for gaseous oxygen,significantly reducing R_(local);the IL modification layers facilitate the formation of continuous proton transport networks,increasing proton conductivity.The incorporation of BMImHSO_(4)@MOF-808 in a low-Pt CCL(0.1 mg_(Pt)cm^(-2))yields a peak power density of 1.9 W cm^(-2)for PEMFC under H_(2)-O_(2)condition,and ca.20%increase of power density under H_(2)-air condition as compared with conventional CCL,indicating the prospect of IL-MOF composites as an efficient additive to enhance the performance of PEMFCs.
文摘Direct conversion of methane using a metal-loaded ZSM-5 zeolite prepared viaacidic ion exchange was investigated to elucidate the roles of metal and acidity in the formation ofliquid hydrocarbons. ZSM-5 (SiO_2/Al_2O_3=30) was loaded with different metals (Cr, Cu and Ga)according to the acidic ion-exchange method to produce metal-loaded ZSM-5 zeolite catalysts. XRD,NMR, FT-IR and N_2 adsorption analyses indicated that Cr and Ga species managed to occupy thealuminum positions in the ZSM-5 framework. In addition, Cr species were deposited in the pores ofthe structure. However, Cu oxides were deposited on the surface and in the mesopores of the ZSM-5zeolite. An acidity study using TPD-NH_3, FT-IR, and IR-pyridine analyses revealed that the totalnumber of acid sites and the strengths of the Broensted and Lewis acid sites were significantlydifferent after the acidic ion exchange treatment. Cu loaded HZSM-5 is a potential catalyst fordirect conversion of methane to liquid hydrocarbons. The successful production of gasoline via thedirect conversion of methane depends on the amount of aluminum in the zeolite framework and thestrength of the Broensted acid sites.
基金supported by the Joint Studies Program (No. 18-502, and 19-501) of UVSOR-IMS, Japansupported by the Joint Studies Program (No. 2000G274, 2004G110)of KEK-PF, Japan
文摘For direct gas to liquid（GTL）,a novel process producing energy sources for methane dehydroaromatization is needed.Supporting MoO3 on H-MFI zeolite shows the high catalytic capacity and a selective activity for dehydroaromatization of methane to benzene at 973 K in a fixed bed reactor.On the other hand,deactivation by coke on the active sites in all the catalysts is formed during the reaction.H2 co-feed suppressed the deactivation,which is probably due to the decrease in coking amount.Mo K-edge X-ray absorption fine structure（XAFS） results showed the formation of dispersed Mo2C species with low crystallinity after dehydroaromatization.Mo LIII-edge XANES（X-ray absorption near-edge structure） indicated the formation of active Mo species including Mo2C and Mo-oxycarbide（MoOxCy）,where the redox state should be independent in the absence/presence of H2.It is concluded that Mo-oxycarbide species act as highly active species,and their stability affected the durable activity in the presence of H2.
基金This work was financially supported by the National Science Foundation of China (Project No.20533010).
文摘A reversible storage-release process switched by a temperature difference of 10 ℃ around room temperature can be realized. This fast, recyclable, energy efficient, low cost and green system within a wide range of temperature and pressure is reported here for the first time. The system is believed to open up a new route for the storage and homogeneous utilization of methane.
基金Project(2017XKQY012)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SEM)are employed to visualize and quantify morphological evolution characteristics of fractures in coal after LN2 thermal shocking treatments.LN2 thermal shocking leads to a denser fracture network than its original state with coal porosity growth rate increasing up to 183.3%.The surface porosity of theμCT scanned layers inside the coal specimen is influenced by LN2 thermal shocking which rises from 18.76%to 215.11%,illustrating the deformation heterogeneity of coal after LN2 thermal shocking.The cracking effect of LN2 thermal shocking on the surface of low porosity is generally more effective than that of high surface porosity,indicating the applicability of LN2 thermal shocking on low-permeability CBM reservoir stimulation.The characteristics of SEM scanned coal matrix in the coal powder and the coal block after the LN2 thermal shocking presented a large amount of deep and shallow progressive scratch layers,fracture variation diversity(i.e.extension,propagation,connectivity,irregularity)on the surface of the coal block and these were the main reasons leading to the decrease of the uniaxial compressive strength of the coal specimen.
基金supported by the National Science Foundation of China(No.20973028)
文摘Pd-containing ionic liquid （IL） 1-hexyl-3-methylimidazolium tetrafluoroborate （C6MIMBF4） immobilized on γ-Al2O3 （Pd-IL/γ-Al2O3） was prepared and characterized by Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM） and Brunauer-Emmett- Teller （BET） analysis. The influences of C6MIMBF4 loading and Pd on methane conversion to C2 hydrocarbons under cold plasma were investigated. FTIR and SEM analyses indicated that C6MIMBF4 had been successfully immobilized on γ-Al2O3 and the C6MIMBF4 showed excellent stability under cold plasma. The results of BET and methane conversion showed that with the increase in immobilization amount of C6MIMBF4 onto γ-Al2O3, the specific surface area and pore volume of IL/γ-Al2O3 decreased, while the selectivity and yield of C2 hydrocarbons increased. The selectivity of C2 hydrocarbons was 94.6% when the loading of C6MIMBF4 was 40%, and the percentage of C2H4 in C2 hydrocarbons was as high as 64% when using Pd-IL/γ-Al2O3 as a catalyst with no conventional thermal reduction treatment. Optical emission spectra （OES） from the cold plasma reactor during methane conversion were also studied. The results indicated that the intensity of the C2, CH, H, and C active species from methane and hydrogen decomposition increased when IL/γ-Al2O3 or Pd-IL/γ-Al2O3 was introduced into the plasma system. Based on the analyses of the gas product and OES spectra, it can be concluded that the surface catalyzed reactions between plasma and ionic liquid were very important for the reduction of Pd2＋ and the formation of C2H4.
基金Supported by Ministry of Science,Technology and Environment,Malaysia.
文摘Metal containing ZSM-5 can produce higher hydrocarbons in methane oxidation. Many researchers have studied the applicability of HZSM-5 and modify ZSM-5 for methane conversion to liquid hydrocarbons, but their research results still lead to low conversion, low selectivity and low heat resistance. The modified HZSM-5, by loading with tungsten （W）, could enhance its heat resistant performance, and the high reaction temperature （800 ℃） did not lead to a loss of the W component by sublimation. The loading of HZSM-5 with tungsten and copper （Cu） resulted in an increment in the methane conversion as well as CO2 and C5＋ selectivities. In contrast, CO, C2-3 and H2O selectivities were reduced. The process of converting methane to liquid hydrocarbons （C5＋） was dependent on the metal surface area and the acidity of the zeolite. High methane conversion and C5＋ selectivity, and low H20 selectivity are obtained over W/3.0Cu/HZSM.
文摘The conversion of methane to liquid fuels is still in the development process. The modified HZSM-5 by loading with Tungsten （W） enhanced its heat resistant performance, and the high reaction temperature （800℃） did not lead to the loss of W component by sublimation. The loading of ZSM-5 with Tungsten and Copper （Cu） resulted in an increment in the methane conversion, CO2, and C5＋ selectivities. The high methane conversion and C5＋ selectivity, and low H2O selectivity are obtained by using W/3.0Cu/ZSM-5. The optimization of methane conversion over 3.0 W/3.0Cu/ZSM-5 under different temperature and oxygen concentration using response surface methodology （RSM） are studied. The optimum point for methane conversion is 19% when temperature is 753 ℃, and oxygen concentration is 12%. The highest C5＋ selectivity is 27% when temperature is 751 ℃. and oxwen concentration is 11%.
基金the National Natural Science Foundation of China(No.20772025)the Program for Science & Technology Innovation Talents in Universities of Henan Province(No.2008HASTIT006)the Natural Science Foundation of Department of Education of Henan Province(No.2008A150013).
文摘Promoted and mediated by an ionic liquid-[bmim][BF4], fused pyrans or arylbis（4-hydroxy-6-methyl-2-oxo-2H-pyran-3- yl）methanes were efficiently and selectively prepared from the reaction of aldehyde and 4-hydroxy-6-methyl-2-oxo-pyran with or without acetic anhydride. By using these novel procedures, pyrimidine nucleoside-fused pyran and arylbis（pyranon-3-yl）methane hybrids with potential biological activities were constructed.
基金The project was supported by the National Natural Science Foundation of China （No. 20272018） the Guangdong Natural Science Foundation （No. 04010458, 021166）.
文摘Efficient electrophilic substitution reaction of indoles with various aromatic aldehydes were carried out with a catalytic amount of sodium hydrogensulfate monohydrate （NaHSO4·H20） in ionic liquid n-butylpyridinium tetrafluoroborate （[Bpy]BF4） to afford the corresponding bi（indolyl）methanes in excellent yields. The notable advantages of this protocol in terms of low cost of catalyst and ionic liquid, mild conditions, simple operation, short reaction time, high yields and recycling of the ionic liquid.
基金the National Key R&D Program of China(No.2021YFA1500800)National Natural Science Foundation of China(No.22072106).
文摘Methane chemistry is one of the“Holy Grails of catalysis”.It is highly desirable but challenge to transform methane into value-added chemicals,because of its high C-H bonding energy(435 kJ/mol),lack ofπbonding or unpaired electrons.Currently,commercial methane conversion is usually carried out in harsh conditions with enormous energy input.Photocatalytic partial oxidation of methane to liquid oxygenates(PPOMO)is a future-oriented technology towards realizing high efficiency and high selectivity under mild conditions.The selection of oxidant is crucial to the PPOMO performance.Hence,attentions are paid to the research progress of PPOMO with various oxidants(O_(2),H_(2)O,H_(2)O_(2)and other oxidants).Moreover,the activation of the selected oxidants is also highly emphasized.Meanwhile,we summarized the methane activation mechanisms focusing on the C-H bond that was broken mainly by·OH radical,O-specie or photogenerated hole(h+).Finally,the challenges and prospects in this subject are briefly discussed.
基金supported by the Natural Science Founda-tion of Chongqing(cstc2021jcyj-msxmX0420)Natural Science Foundation of Sichuan(2023NSFSC0088)。
文摘Hydrogen production from electrochemical water splitting is a promising strategy to generate green energy,which requires the development of efficient and stable electrocatalysts for the hydrogen evolution reaction and the oxygen evolution reaction(HER and OER).Ionic liquids(ILs)or poly(ionic liquids)(PILs),containing heteroatoms,metal-based anions,and various structures,have been frequently involved as precursors to prepare electrocatalysts for water splitting.Moreover,ILs/PILs possess high conductivity,wide electrochemical windows,and high thermal and chemical stability,which can be directly applied in the electrocatalysis process with high durability.In this review,we focus on the studies of ILs/PILs-derived electrocatalysts for HER and OER,where ILs/PILs are applied as heteroatom dopants and metal precursors to prepare catalysts or are directly utilized as the electrocatalysts.Due to those attractive properties,IL/PIL-derived electrocatalysts exhibit excellent performance for electrochemical water splitting.All these accomplishments and developments are systematically summarized and thoughtfully discussed.Then,the overall perspectives for the current challenges and future developments of ILs/PILs-derived electrocatalysts are provided.
