Hydrogen is an indispensable energy carrier for the sustainable development of human society.Nevertheless,its storage,transportation,and in situ generation still face significant challenges.Methanol can be used as an ...Hydrogen is an indispensable energy carrier for the sustainable development of human society.Nevertheless,its storage,transportation,and in situ generation still face significant challenges.Methanol can be used as an intermediate carrier for hydrogen supplies,providing hydrogen energy through instant methanol conversion.In this study,a sorption-enhanced,chemical-looping,oxidative steam methanol-reforming(SECLOSRM)process is proposed using CuO–MgO for the on-board hydrogen supply,which could be a promising method for safe and efficient hydrogen production.Aspen Plus software was used for feasibility verification and parameter optimization of the SECL-OSRM process.The effects of CuO/CH_(3)OH,MgO/CH_(3)OH,and H_(2)O/CH_(3)OH mole ratios and of temperature on H_(2)production rate,H utilization efficiency,CH_(3)OH conversion,CO concentration,and system heat balance are discussed thoroughly.The results indicate that the system can be operated in autothermal conditions with high-purity hydrogen(99.50 vol%)and ultra-low-concentration CO(<50 ppm)generation,which confirms the possibility of integrating low-temperature proton-exchange membrane fuel cells(LT-PEFMCs)with the SECL-OSRM process.The simulation results indicate that the CO can be modulated in a lower concentration by reducing the temperature and by improving the H_(2)O/CH_(3)OH and MgO/CH_(3)OH mole ratios.展开更多
Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures, annealing temperatures, and annealing times. The effects of temperature on the optical properties, chemical composition, structure, a...Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures, annealing temperatures, and annealing times. The effects of temperature on the optical properties, chemical composition, structure, and laser- induced damage threshold （LIDT） are systematically investigated. The results show that the increase of deposition temperature decreases the film transmittance slightly, yet annealing below 923 K is beneficial for the transmittance. The XRD analysis reveals that the film is in the amorphous phase when annealed below 873 K and in thehexagonal phase when annealed at 1073 K. While an interesting near-crystalline phase is found when annealed at 923 K. The LIDT increases with the deposition temperature increasing, whereas it increases firstly and then decreases as the annealing temperature increases. In addition, the increase of the annealing time from 4 h to 12 h is favourable to improving the LIDT, which is mainly due to the improvement of the O/Ta ratio. The highest LIDT film is obtained when annealed at 923 K, owing to the lowest density of defect.展开更多
CO_(2)reduction reaction(CO_(2)RR)electrolyzers based on gas diffusion electrode(GDE)enable the direct mass transfer of CO_(2)to the catalyst surface for participation in the reaction,thereby establishing an efficient...CO_(2)reduction reaction(CO_(2)RR)electrolyzers based on gas diffusion electrode(GDE)enable the direct mass transfer of CO_(2)to the catalyst surface for participation in the reaction,thereby establishing an efficient three-phase reaction interface that significantly enhances current density.However,current hydrophobic modification methods face difficulties in achieving precise and substantial control over wettability,and the hydrophobic modifiers tend to significantly impair the conductivity of the electrode and ion transport capabilities.This study employs Nafion ionomers to hydrophobically modify the threedimensional catalyst layer,revealing the bifunctionality of Nafion.The fluorinated backbone of Nafion ensures the hydrophobicity of the entire catalyst layer,while its sulfonic acid groups promote ion transport,without significantly affecting the conductivity of the electrode.Furthermore,by employing modifiers with distinct wettability characteristics,a highly efficient and large-scale manipulation of the hydrophilic/hydrophobic properties of the catalyst layer was successfully realized.The electrode,constructed with silver nanopowder as a representative catalyst and modified with the hydrophobic ionomer Nafion,exhibits a substantial enhancement in both catalytic activity and durability.The optimized electrode exhibited exceptional electrocatalytic performance in both flow cell and membrane electrode assembly(MEA)configurations.Notably,in the MEA,the electrode achieved a remarkable CO Faradaic efficiency(FE)of 93.3%at a total current density of 200 mA cm^(-2),while maintaining stable operation for over 62 h.展开更多
The performance of the fuel electrode in a solid oxide electrolysis cell(SOEC)is crucial to facilitating fuel gas electrolysis and is the key determinant of overall electrolysis efficiency.Nevertheless,the commerciali...The performance of the fuel electrode in a solid oxide electrolysis cell(SOEC)is crucial to facilitating fuel gas electrolysis and is the key determinant of overall electrolysis efficiency.Nevertheless,the commercialization of integrated CO_(2)-H_(2)O electrolysis in SOEC remains constrained by suboptimal catalytic efficiency and long-term stability limitations inherent to conventional fuel electrode architec-tures.A novel high-entropy Sr_(2)FeTi_(0.2)Cr_(0.2)Mn_(0.2)Mo_(0.2)Co_(0.2)O_(6−δ)(SFTCMMC)was proposed as a prospective electrode material of co-elec-trolysis in this work.The physicochemical properties and electrochemical performance in the co-electrolysis reaction were investigated.Full cell is capable of electrolyzing H_(2)O and CO_(2)effectively with an applied voltage.The effects of temperature,H_(2)O and CO_(2)concentra-tions,and applied voltage on the electrochemical performance of Sc_(0.18)Zr_(0.82)O_(2−δ)(SSZ)-electrolyte supported SOEC were investigated by varying the operating conditions.The SOEC obtains a favorable electrolysis current density of 1.47 A·cm^(−2)under co-electrolysis condi-tion at 850℃ with 1.5 V.Furthermore,the cell maintains stable performance for 150 h at 1.3 V,and throughout this period,no carbon de-position is detected.The promising findings suggest that the high-entropy SFTCMMC perovskite is a viable fuel electrode candidate for efficient H_(2)O/CO_(2)co-electrolysis.展开更多
CO_(2) hydrogenation to methanol is a critical technology for hydrogen energy conversion and a promising approach to mitigate the energy crisis and greenhouse effect.However,developing highly selective catalysts remai...CO_(2) hydrogenation to methanol is a critical technology for hydrogen energy conversion and a promising approach to mitigate the energy crisis and greenhouse effect.However,developing highly selective catalysts remains a major challenge for its practical application.Herein,we synthesize an efficient CoCuInO-r catalyst with Cu_(11)In_(9) and Co^(0) dual sites on In_(2)O_(3) via a sol-gel method.The Cu_(11)In_(9) intermetallic compound enhances H_(2) adsorption capacity and strength,and increases oxygen vacancy concentration on the catalyst surface,thereby improving CO_(2) activation and hydrogenation efficiency.Meanwhile,Co^(0) suppresses the desorption of the*CO species,facilitating its further hydrogenation to methanol.In-situ DRIFTS experiments indicate that the CO_(2) hydrogenation to methanol over CoCuInO-r follows the formate pathway.Compared with CuInO-r(containing Cu_(11)In_(9) on In_(2)O_(3)),CoCuInO-r exhibits a~20%increase in methanol selectivity and a 2-fold higher methanol space-time yield,reaching 7.68 mmol·g^(-1)·h^(-1) at 300℃ and 4 MPa.展开更多
Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or rea...Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or reactor on the catalytic per-formance of various metal oxides remains insuffi ciently understood.This study examines the infl uence of water on supported metal oxide catalysts,specifi cally CoO x/Al_(2)O_(3),VO x/Al_(2)O_(3),and an industrial analog CrO x/Al_(2)O_(3) catalyst.By combining titration experiments,in situ Fourier transform infrared spectroscopy,kinetic analysis,and isotopic techniques,we demon-strate that even trace amounts of water can markedly suppress PDH performance via dissociative adsorption on the oxide surface.Methanol pretreatment eff ectively scavenges adsorbed water,recovering Lewis acid-base sites and consequently restoring PDH activity.This work underscores the profound inhibitory role of trace water in PDH over metal oxide catalysts and illustrates the potential of methanol pretreatment as an effective strategy to mitigate this limitation.展开更多
Reversible protonic ceramic electrochemical cells(RPCECs),which are capable of efficiently converting electrical and chemical energy in mutual directions,are considered highly promising alternatives for bidirectional ...Reversible protonic ceramic electrochemical cells(RPCECs),which are capable of efficiently converting electrical and chemical energy in mutual directions,are considered highly promising alternatives for bidirectional electrical energy generation or storage.However,the sluggish electrocatalytic activity at low temperatures and unsatisfactory operational durability of oxygen electrodes remain the primary challenges to the commercial application of R-PCECs.Here,the degradation mechanism of the BaFe_(0.4)Co_(0.4)Zr_(0.1)Y_(0.1)O_(3−δ)(BFCZY)oxygen electrode under humid conditions is systematically investigated.This degradation can be attributed to the formation of BaCO_(3)caused by water-facilitated Ba segregation.The activity and stability of the BFCZY oxygen electrode are significantly improved through heterointerface engineering by infiltrating the BaCO_(3)(BCO)catalyst.At 600°C in 30 vol%H_(2)O-air,heterointerface engineering decreases the polarization resistance of the BFCZY electrode by half(from 0.42 to 0.21Ω·cm^(2))and the decay rate by more than one order of magnitude(from 0.384 to 0.026Ω·cm^(2)/100 h).Moreover,an RPCEC with a BCO-BFCZY oxygen electrode exhibited high activity and stability in both fuel cell and water electrolysis modes.The substantially increased electrocatalytic activity and stability of the oxygen electrode are attributed primarily to the improved surface oxygen exchange process and inhibited Ba segregation.展开更多
Based on the problems caused by many oxygen-containing functional groups and poor floatability on the surface of low rank coal,the characteristics of low rank coal were analyzed systematically by means of scanning ele...Based on the problems caused by many oxygen-containing functional groups and poor floatability on the surface of low rank coal,the characteristics of low rank coal were analyzed systematically by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-Ray photoelectron spectroscopy(XPS)techniques.The bubble-particle induction time was used to determine the characterization of the bubble-particle attachment,and the bubble-particle attachment of low rank coal modified by soaking the coal samples in an acid or alkaline solution was analyzed.The floatability of the modified coal surface was verified by flotation tests.The results show that the particle size of 0.125–0.074 mm of the coal sample exhibited better bubble-particle attachment characteristics.The small bubble,the larger approach velocity of bubble and the larger bubble deformation were more helpful to enhance the bubbleparticle attachment.For an acid solution,the smaller the p H was and the longer the soaking time was,the better the floatability of the coal sample and the higher the combustible material recovery were.The combustible material recovery of low rank coal was increased to 78.79%by soaking the sample in an acid solution of pH=0 for 180 min.On the contrary there was a best concentration for the alkaline solution.展开更多
The effect of Co doping on ceria-zirconia mixed oxides was investigated for Co0.1Ce0.6Zr0.3Ox sample prepared by sol-gel method. The Pd-only three-way catalyst （TWC） was obtained by incipient wetness impregnation wi...The effect of Co doping on ceria-zirconia mixed oxides was investigated for Co0.1Ce0.6Zr0.3Ox sample prepared by sol-gel method. The Pd-only three-way catalyst （TWC） was obtained by incipient wetness impregnation with 0.5 wt.% Pd loading. The structural and oxygen handling properties were analyzed by X-ray diffraction （XRD）, H2-temperature programmed reduction （H2-TPR） and the dynamic oxygen storage capacity （DOSC）. The introduction of Co into ceria-zirconia lattice strongly modified the mobility of oxygen and enhanced the DOSC performance. Pd-only TWC based on the Co0.1Ce0.6Zr0.3Ox support exhibited superior activity for water-gas shift and steam reforming and ampli- fied amplitude of stoichiometric window.展开更多
Copper-exchanged chabazite（Cu/CHA） catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na＋ ions on Cu/SAPO-34 for ammonia selective catalytic reduction（NH_3-SC...Copper-exchanged chabazite（Cu/CHA） catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na＋ ions on Cu/SAPO-34 for ammonia selective catalytic reduction（NH_3-SCR） are still unclear. In order to investigate the mechanism, five samples with various Na contents were synthesized and characterized. It was observed that the introduced Na＋ ion-exchanges with H＋and Cu2＋of Cu/SAPO-34. The exchange of H＋is easier than that of isolated Cu2＋. The exchanged Cu2＋ions aggregate and form ＂CuAl_2O4-like＂ species.The NH_3-SCR activity of Cu/SAPO-34 decreases with increasing Na content, and the loss of isolated Cu2＋and acid sites is responsible for the activity loss.展开更多
Recent research on deterministic methods for circulating cooling water systems optimization has been well developed. However, the actual operating conditions of the system are mostly variable, so the system obtained u...Recent research on deterministic methods for circulating cooling water systems optimization has been well developed. However, the actual operating conditions of the system are mostly variable, so the system obtained under deterministic conditions may not be stable and economical. This paper studies the optimization of circulating cooling water systems under uncertain circumstance. To improve the reliability of the system and reduce the water and energy consumption, the influence of different uncertain parameters is taken into consideration. The chance constrained programming method is used to build a model under uncertain conditions, where the confidence level indicates the degree of constraint violation. Probability distribution functions are used to describe the form of uncertain parameters. The objective is to minimize the total cost and obtain the optimal cooling network configuration simultaneously.An algorithm based on Monte Carlo method is proposed, and GAMS software is used to solve the mixed integer nonlinear programming model. A case is optimized to verify the validity of the model. Compared with the deterministic optimization method, the results show that when considering the different types of uncertain parameters, a system with better economy and reliability can be obtained(total cost can be reduced at least 2%).展开更多
China’s energy supply heavily relies on coal and China’s coal resource and water resource has a reverse distribution.The problem of water shortages restricts the applications of wet coal beneficiation technologies i...China’s energy supply heavily relies on coal and China’s coal resource and water resource has a reverse distribution.The problem of water shortages restricts the applications of wet coal beneficiation technologies in drought regions.The present situation highlights the significance and urgency of developing dry beneficiation technologies of coal.Besides,other countries that produce large amounts of coal also encounter serious problem of lack of water for coal beneficiation,such as American,Australia,Canada,South Africa,Turkey and India.Thus,dry coal beneficiation becomes the research hot-points in the field of coal cleaning worldwide in recent years.This paper systematically reviewed the promising research efforts on dry coal beneficiation reported in literature in last 5 years and discussed the progress in developments of dry coal beneficiation worldwide.Finally,we also elaborated the prospects and the challenges of the development of dry coal beneficiation.展开更多
Carbonic anhydrase(CA)as a typical metalloenzyme in biological system can accelerate the hydration/dehydration of carbon dioxide(CO2,the major components of greenhouse gases),which performer with high selectivity,envi...Carbonic anhydrase(CA)as a typical metalloenzyme in biological system can accelerate the hydration/dehydration of carbon dioxide(CO2,the major components of greenhouse gases),which performer with high selectivity,environmental friendliness and superior efficiency.However,the free form of CA is quite expensive(~RMB 3000/100 mg),unstable,and non-reusable as the free form of CA is not easy for recovery from the reaction environment,which severely limits its large-scale industrial applications.The immobilization may solve these problems at the same time.In this context,many efforts have been devoted to improving the chemical and thermal stabilities of CA through immobilization strategy.Very recently,a wide range of available inorganic,organic and hybrid compounds have been explored as carrier materials for CA immobilization,which could not only improve the tolerance of CA in hazardous environments,but also improve the efficiency and recovery to reduce the cost of large-scale application of CA.Several excellent reviews about immobilization methods and application potential of CA have been published.By contrast,in our review,we stressed on the way to better retain the biocatalytic activity of immobilized CA system based on different carrier materials and to solve the problems facing in practical operations well.The concluding remarks are presented with a perspective on constructing efficient CO2 conversion systems through rational combining CA and advanced carrier materials.展开更多
Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the se...Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.展开更多
Multi-principal element alloys exhibit excellent physical,chemical and mechanical properties,and they are used as novel structural materials for potential applications in nuclear energy,hydrogen energy,and petrochemic...Multi-principal element alloys exhibit excellent physical,chemical and mechanical properties,and they are used as novel structural materials for potential applications in nuclear energy,hydrogen energy,and petrochemical fields.However,exposing components made of the alloys to service conditions related to the mentioned applications may induce hydrogen embrittlement(HE)as one of the typical failure mechanisms.In this review,we report and summarize the progress in understanding HE in multi-principal element alloys,with a particular focus on high-entropy alloys(HEAs).The review focuses on four aspects:(1)hydrogen migration behavior(hydrogen dissolution,hydrogen diffusion,and hydrogen traps);(2)factors affecting HE(hydrogen concentration,alloy elements and microstructure);(3)tensile mechanical properties in the presence of hydrogen and micro-damage HE mechanisms;(4)the design concept for preventing hydrogen-induced mechanical degradation.The differences in the HE behavior and failure mechanisms between HEAs and traditional alloys are compared and discussed.Moreover,specific research directions for further investigation of fundamental HE issues and a strategy for a simultaneous improvement in strength and HE resistance are identified.展开更多
Lanthanum-containing(LaX)and cerium-containing X zeolites(CeX)were prepared by a doubleexchange,double-calcination method.By changing the calcination atmospheres between nitrogen and air,the Ce^(IV) contents in CeX ze...Lanthanum-containing(LaX)and cerium-containing X zeolites(CeX)were prepared by a doubleexchange,double-calcination method.By changing the calcination atmospheres between nitrogen and air,the Ce^(IV) contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established.The crystallinity of CeX zeolite was found to be negatively correlated with the Ce^(IV) content.This i s believed to be due to the water formed during the oxidation of Ce^(III),which facilitates the framework dealumination.As a consequence,calcining in air resulted in a great elimination of strong Brønsted acid sites while under nitrogen protection,this phenomenon was mostly hindered and the sample’s acidity was preserved.When tested in a continuously flowed slurry reactor,the catalyst lifetime for isobutane alkylation was found to be linearly related to the strong Brønsted acid concentration.In addition,Ce^(3+)was found more benefit for the hydride transfer compared with La^(3+),which is ascribed to the stronger polarization effect on the CH bond of isobutane.Moreover,the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules.Based on the product distribution,a new catalytic cycle of dimethylhexanes(DMHs)involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.展开更多
Experiments were made for the adsorption of CO2 and N2 on typical adsorbents to investigate the effects of porous structure and surface affinity of adsorbents as well as those of adsorption temperature and pressure th...Experiments were made for the adsorption of CO2 and N2 on typical adsorbents to investigate the effects of porous structure and surface affinity of adsorbents as well as those of adsorption temperature and pressure that might cause the variation of adsorption mechanism. It is shown that polar surface tends to enlarge the adsorption difference between CO2 and N2, and the difference is more sensitive to temperature than the adsorbents with non-polar surface. The adsorbents with non-polar surface are not much sensitive to the effect of water vapor, though the water vapor interferes the separation remarkably. The separation coefficient linearly increases with the micro- pore volume per unit surface area of activated carbons, but no rule is shown on mesoporous silicon materials. The function of adsorption mechanism on the separation is not as much as expected.展开更多
FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen tempe...FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen temperature-programmed reduction （H2-TPR） techniques. The dynamic oxygen storage capacity （DOSC） was investigated by mass spectrometry with CO/O2 transient pulses. The powder XRD data following Rietveld refinement revealed that the solubility limit of iron oxides in the CeO2 was 5 mol% based on Fe/（Ce＋Fe）. The lattice parameters experienced a decrease followed by an increase due to the influence of the maximum solubility limit of iron oxides in the CeO2. TPR analysis revealed that Fe introduction into ceria strongly modified the textual and structural properties, which influenced the oxygen handling properties. DOSC results revealed that Ce-based materials containing Fe oxides with multiple valences contribute to the majority of DOSC. The kinetic analysis indicated that the calculated apparent kinetic parameters obey the compensation effect. The three-way catalytic performance for Pd-only catalysts based on the Fe doping support exhibited the redundant iron species separated out of the CeO2 and interacted with the ceria and Pd species on the surface, which seriously influenced the catalytic properties, especially after hydrothermal aging treatment.展开更多
Noble nanometals are of significance in both scientific interest and technological applications,which are usually obtained by conventional wet-chemical synthesis.Organic surfactants are always used in the synthesis to...Noble nanometals are of significance in both scientific interest and technological applications,which are usually obtained by conventional wet-chemical synthesis.Organic surfactants are always used in the synthesis to prevent unexpected overgrowth and aggregation of noble nanometals.However,the surfactants are hard to remove and may interfere with plasmonic and catalytic studies,remaining surfactant-free synthesis of noble nanometals a challenge.Herein,we report an approach to epitaxial growth of sizecontrolled noble nanometals on MXenes.As piloted by density functional theory calculations,along with work function experimental determination,kinetic and spectroscopic studies,epitaxial growth of noble nanometals is initiated via a mechanism that involves an in situ redox reaction.In the redox,MXenes as two-dimensional solid reductants whose work functions are compatible with the reduction potentials of noble metal cations,enable spontaneous donation of electrons from the MXenes to noble metal cations and reduce the cations into nanoscale metallic metals on the outmost surface of MXenes.Neither surfactants nor external reductants are used during the whole synthesis process,which addresses a long-standing interference issue of surfactant and external reductant in the conventional wet-chemical synthesis.Moreover,the MXenes induced noble nanometals are size-controlled.Impressively,noble nanometals firmly anchored on MXenes exhibit excellent performance towards surface enhanced Raman scattering.Our developed strategy will promote the nanostructure-controlled synthesis of noble nanometals,offering new opportunities to further improve advanced functional properties towards practical applications.展开更多
The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration freq...The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration frequency and amplitude, and gas velocity on these characteristics were considered. The average size, average density, size deviation coefficient, and density deviation coefficient were used to identify lignite size and density. The separation efficiency was adopted to evaluate the segregation performance,and the segregation mechanisms were explored. The results show that ε(size,max) of heterogeneous multisize-component lignite with K_(size) = 65% reaches 80% at f= 20 Hz, A = 5 mm, and N =(1,3). ε_(density,max) Of heterogeneous multi-density-component lignite with K_(density)= 25% reaches 50% at f = 15 Hz, A = 5 mm,and N =(1,1.5). The density segregations of 1-3 and 3-6 mm multi-component mixtures are remarkable,ε_(density,max)= 42% and 31% at f= 14 and 16 Hz, and A = 3 and 5 mm, respectively. The size segregation of 1-6 mm multi-component mixture is prominent and ε_(size,max)= 55% at f= 15 Hz, A = 5 mm. The mediumsized mixture with a narrow size distribution at low frequency is favorable for density segregation,and a mixture with a wider size distribution at high frequency is most favorable for size segregation.Precise control of gas flow and vibration as well as optimal design of the fluidized bed can improve the performance of segregation in the vibrated gas-fluidized bed.展开更多
基金supported by the National Key R&D Program of China(2018YFE0111100)National Natural Science Foundation of China(52106193,21908162)+2 种基金the Natural Science Foundation of Hunan Province(2021JJ40756)the Science and Technology Innovation Program of Hunan Province(2020GK2070)the Innovation-Driven Project of Central South University(2020CX008)
文摘Hydrogen is an indispensable energy carrier for the sustainable development of human society.Nevertheless,its storage,transportation,and in situ generation still face significant challenges.Methanol can be used as an intermediate carrier for hydrogen supplies,providing hydrogen energy through instant methanol conversion.In this study,a sorption-enhanced,chemical-looping,oxidative steam methanol-reforming(SECLOSRM)process is proposed using CuO–MgO for the on-board hydrogen supply,which could be a promising method for safe and efficient hydrogen production.Aspen Plus software was used for feasibility verification and parameter optimization of the SECL-OSRM process.The effects of CuO/CH_(3)OH,MgO/CH_(3)OH,and H_(2)O/CH_(3)OH mole ratios and of temperature on H_(2)production rate,H utilization efficiency,CH_(3)OH conversion,CO concentration,and system heat balance are discussed thoroughly.The results indicate that the system can be operated in autothermal conditions with high-purity hydrogen(99.50 vol%)and ultra-low-concentration CO(<50 ppm)generation,which confirms the possibility of integrating low-temperature proton-exchange membrane fuel cells(LT-PEFMCs)with the SECL-OSRM process.The simulation results indicate that the CO can be modulated in a lower concentration by reducing the temperature and by improving the H_(2)O/CH_(3)OH and MgO/CH_(3)OH mole ratios.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61107080 and 50921002)the Natural Science Foundation of Jiangsu Province,China (Grant No. BK2011223)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China (New Teachers) (Grant No.20110095120018)the China Postdoctoral Science Foundation (Grant No. 20110491472)the Fundamental Research Funds for the Central Universities,China (Grant No. 2012QNA03)
文摘Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures, annealing temperatures, and annealing times. The effects of temperature on the optical properties, chemical composition, structure, and laser- induced damage threshold （LIDT） are systematically investigated. The results show that the increase of deposition temperature decreases the film transmittance slightly, yet annealing below 923 K is beneficial for the transmittance. The XRD analysis reveals that the film is in the amorphous phase when annealed below 873 K and in thehexagonal phase when annealed at 1073 K. While an interesting near-crystalline phase is found when annealed at 923 K. The LIDT increases with the deposition temperature increasing, whereas it increases firstly and then decreases as the annealing temperature increases. In addition, the increase of the annealing time from 4 h to 12 h is favourable to improving the LIDT, which is mainly due to the improvement of the O/Ta ratio. The highest LIDT film is obtained when annealed at 923 K, owing to the lowest density of defect.
基金National Key R&D Program of China(2023YFA1507902,2021YFA1500804)the National Natural Science Foundation of China(22121004,22038009,22250008)+2 种基金the Haihe Laboratory of Sustainable Chemical Transformations(CYZC202107)the Program of Introducing Talents of Discipline to Universities,China(No.BP0618007)the Xplorer Prize,China,for their financial support。
文摘CO_(2)reduction reaction(CO_(2)RR)electrolyzers based on gas diffusion electrode(GDE)enable the direct mass transfer of CO_(2)to the catalyst surface for participation in the reaction,thereby establishing an efficient three-phase reaction interface that significantly enhances current density.However,current hydrophobic modification methods face difficulties in achieving precise and substantial control over wettability,and the hydrophobic modifiers tend to significantly impair the conductivity of the electrode and ion transport capabilities.This study employs Nafion ionomers to hydrophobically modify the threedimensional catalyst layer,revealing the bifunctionality of Nafion.The fluorinated backbone of Nafion ensures the hydrophobicity of the entire catalyst layer,while its sulfonic acid groups promote ion transport,without significantly affecting the conductivity of the electrode.Furthermore,by employing modifiers with distinct wettability characteristics,a highly efficient and large-scale manipulation of the hydrophilic/hydrophobic properties of the catalyst layer was successfully realized.The electrode,constructed with silver nanopowder as a representative catalyst and modified with the hydrophobic ionomer Nafion,exhibits a substantial enhancement in both catalytic activity and durability.The optimized electrode exhibited exceptional electrocatalytic performance in both flow cell and membrane electrode assembly(MEA)configurations.Notably,in the MEA,the electrode achieved a remarkable CO Faradaic efficiency(FE)of 93.3%at a total current density of 200 mA cm^(-2),while maintaining stable operation for over 62 h.
基金supported by the National Natural Science Foundation of China(No.52472270)the Basic Research Program of Jiangsu(No.BK20243049)the Fundamental Research Funds for the Central Universities(No.2023KYJD1010).
文摘The performance of the fuel electrode in a solid oxide electrolysis cell(SOEC)is crucial to facilitating fuel gas electrolysis and is the key determinant of overall electrolysis efficiency.Nevertheless,the commercialization of integrated CO_(2)-H_(2)O electrolysis in SOEC remains constrained by suboptimal catalytic efficiency and long-term stability limitations inherent to conventional fuel electrode architec-tures.A novel high-entropy Sr_(2)FeTi_(0.2)Cr_(0.2)Mn_(0.2)Mo_(0.2)Co_(0.2)O_(6−δ)(SFTCMMC)was proposed as a prospective electrode material of co-elec-trolysis in this work.The physicochemical properties and electrochemical performance in the co-electrolysis reaction were investigated.Full cell is capable of electrolyzing H_(2)O and CO_(2)effectively with an applied voltage.The effects of temperature,H_(2)O and CO_(2)concentra-tions,and applied voltage on the electrochemical performance of Sc_(0.18)Zr_(0.82)O_(2−δ)(SSZ)-electrolyte supported SOEC were investigated by varying the operating conditions.The SOEC obtains a favorable electrolysis current density of 1.47 A·cm^(−2)under co-electrolysis condi-tion at 850℃ with 1.5 V.Furthermore,the cell maintains stable performance for 150 h at 1.3 V,and throughout this period,no carbon de-position is detected.The promising findings suggest that the high-entropy SFTCMMC perovskite is a viable fuel electrode candidate for efficient H_(2)O/CO_(2)co-electrolysis.
基金financial support from the National Key Research and Development Program of China(2022YFB4101800)National Natural Science Foundation of China(22278298)the Key Research&Development Program of Shandong Province,China(2024CXGC010410).
文摘CO_(2) hydrogenation to methanol is a critical technology for hydrogen energy conversion and a promising approach to mitigate the energy crisis and greenhouse effect.However,developing highly selective catalysts remains a major challenge for its practical application.Herein,we synthesize an efficient CoCuInO-r catalyst with Cu_(11)In_(9) and Co^(0) dual sites on In_(2)O_(3) via a sol-gel method.The Cu_(11)In_(9) intermetallic compound enhances H_(2) adsorption capacity and strength,and increases oxygen vacancy concentration on the catalyst surface,thereby improving CO_(2) activation and hydrogenation efficiency.Meanwhile,Co^(0) suppresses the desorption of the*CO species,facilitating its further hydrogenation to methanol.In-situ DRIFTS experiments indicate that the CO_(2) hydrogenation to methanol over CoCuInO-r follows the formate pathway.Compared with CuInO-r(containing Cu_(11)In_(9) on In_(2)O_(3)),CoCuInO-r exhibits a~20%increase in methanol selectivity and a 2-fold higher methanol space-time yield,reaching 7.68 mmol·g^(-1)·h^(-1) at 300℃ and 4 MPa.
基金supported by the National Key R&D Program of China(No.2023YFA1507800)the National Science Foundation of China(Nos.22121004,22122808,22478279,and 22108201)+1 种基金the Haihe Laboratory of Sustainable Chemical Trans-formations,the Program of Introducing Talents of Discipline to Uni-versities(No.BP0618007)the XPLORER PRIZE.
文摘Metal oxide catalysts are widely employed in propane dehydrogenation(PDH)for propylene synthesis,requiring sequential reduction-reaction-regeneration cycles.However,the eff ect of water present in the inlet gas or reactor on the catalytic per-formance of various metal oxides remains insuffi ciently understood.This study examines the infl uence of water on supported metal oxide catalysts,specifi cally CoO x/Al_(2)O_(3),VO x/Al_(2)O_(3),and an industrial analog CrO x/Al_(2)O_(3) catalyst.By combining titration experiments,in situ Fourier transform infrared spectroscopy,kinetic analysis,and isotopic techniques,we demon-strate that even trace amounts of water can markedly suppress PDH performance via dissociative adsorption on the oxide surface.Methanol pretreatment eff ectively scavenges adsorbed water,recovering Lewis acid-base sites and consequently restoring PDH activity.This work underscores the profound inhibitory role of trace water in PDH over metal oxide catalysts and illustrates the potential of methanol pretreatment as an effective strategy to mitigate this limitation.
基金the National Key R&D Program of China(No.2021YFB4001502)is highly appreciated。
文摘Reversible protonic ceramic electrochemical cells(RPCECs),which are capable of efficiently converting electrical and chemical energy in mutual directions,are considered highly promising alternatives for bidirectional electrical energy generation or storage.However,the sluggish electrocatalytic activity at low temperatures and unsatisfactory operational durability of oxygen electrodes remain the primary challenges to the commercial application of R-PCECs.Here,the degradation mechanism of the BaFe_(0.4)Co_(0.4)Zr_(0.1)Y_(0.1)O_(3−δ)(BFCZY)oxygen electrode under humid conditions is systematically investigated.This degradation can be attributed to the formation of BaCO_(3)caused by water-facilitated Ba segregation.The activity and stability of the BFCZY oxygen electrode are significantly improved through heterointerface engineering by infiltrating the BaCO_(3)(BCO)catalyst.At 600°C in 30 vol%H_(2)O-air,heterointerface engineering decreases the polarization resistance of the BFCZY electrode by half(from 0.42 to 0.21Ω·cm^(2))and the decay rate by more than one order of magnitude(from 0.384 to 0.026Ω·cm^(2)/100 h).Moreover,an RPCEC with a BCO-BFCZY oxygen electrode exhibited high activity and stability in both fuel cell and water electrolysis modes.The substantially increased electrocatalytic activity and stability of the oxygen electrode are attributed primarily to the improved surface oxygen exchange process and inhibited Ba segregation.
基金financially supported by the National Key R&D Program of China(No.2018YFC0604702)the National Natural Science Foundation of China(No.51774284).
文摘Based on the problems caused by many oxygen-containing functional groups and poor floatability on the surface of low rank coal,the characteristics of low rank coal were analyzed systematically by means of scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-Ray photoelectron spectroscopy(XPS)techniques.The bubble-particle induction time was used to determine the characterization of the bubble-particle attachment,and the bubble-particle attachment of low rank coal modified by soaking the coal samples in an acid or alkaline solution was analyzed.The floatability of the modified coal surface was verified by flotation tests.The results show that the particle size of 0.125–0.074 mm of the coal sample exhibited better bubble-particle attachment characteristics.The small bubble,the larger approach velocity of bubble and the larger bubble deformation were more helpful to enhance the bubbleparticle attachment.For an acid solution,the smaller the p H was and the longer the soaking time was,the better the floatability of the coal sample and the higher the combustible material recovery were.The combustible material recovery of low rank coal was increased to 78.79%by soaking the sample in an acid solution of pH=0 for 180 min.On the contrary there was a best concentration for the alkaline solution.
基金Project supported by National High-Tech Research and Development Program of China (2011AA03A405)the Key Program of Tianjin Natural Science Foundation (09JCZDJC26600)
文摘The effect of Co doping on ceria-zirconia mixed oxides was investigated for Co0.1Ce0.6Zr0.3Ox sample prepared by sol-gel method. The Pd-only three-way catalyst （TWC） was obtained by incipient wetness impregnation with 0.5 wt.% Pd loading. The structural and oxygen handling properties were analyzed by X-ray diffraction （XRD）, H2-temperature programmed reduction （H2-TPR） and the dynamic oxygen storage capacity （DOSC）. The introduction of Co into ceria-zirconia lattice strongly modified the mobility of oxygen and enhanced the DOSC performance. Pd-only TWC based on the Co0.1Ce0.6Zr0.3Ox support exhibited superior activity for water-gas shift and steam reforming and ampli- fied amplitude of stoichiometric window.
基金financially supported by the National Key Research and Development program(No.2017YFC0211302)the National Natural Science Foundation of China(No.21676195)+1 种基金the Science Fund of State Key Laboratory of Engine Reliability(No.skler-201714)finical support from GM Global Research&Development(No.GAC1539)
文摘Copper-exchanged chabazite（Cu/CHA） catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na＋ ions on Cu/SAPO-34 for ammonia selective catalytic reduction（NH_3-SCR） are still unclear. In order to investigate the mechanism, five samples with various Na contents were synthesized and characterized. It was observed that the introduced Na＋ ion-exchanges with H＋and Cu2＋of Cu/SAPO-34. The exchange of H＋is easier than that of isolated Cu2＋. The exchanged Cu2＋ions aggregate and form ＂CuAl_2O4-like＂ species.The NH_3-SCR activity of Cu/SAPO-34 decreases with increasing Na content, and the loss of isolated Cu2＋and acid sites is responsible for the activity loss.
基金Financial support from the National Natural Science Foundation of China (22022816, 22078358)。
文摘Recent research on deterministic methods for circulating cooling water systems optimization has been well developed. However, the actual operating conditions of the system are mostly variable, so the system obtained under deterministic conditions may not be stable and economical. This paper studies the optimization of circulating cooling water systems under uncertain circumstance. To improve the reliability of the system and reduce the water and energy consumption, the influence of different uncertain parameters is taken into consideration. The chance constrained programming method is used to build a model under uncertain conditions, where the confidence level indicates the degree of constraint violation. Probability distribution functions are used to describe the form of uncertain parameters. The objective is to minimize the total cost and obtain the optimal cooling network configuration simultaneously.An algorithm based on Monte Carlo method is proposed, and GAMS software is used to solve the mixed integer nonlinear programming model. A case is optimized to verify the validity of the model. Compared with the deterministic optimization method, the results show that when considering the different types of uncertain parameters, a system with better economy and reliability can be obtained(total cost can be reduced at least 2%).
基金The study is supported by the National Key Basic Research Program of China(2012CB214904)the National Natural Science Foundation of China(51221462,51134022,51174203)+1 种基金the Research Fund for the Doctoral Program of Higher Education(20120095130001)the Natural Science Foundation of Jiangsu Province(BK20140209).
文摘China’s energy supply heavily relies on coal and China’s coal resource and water resource has a reverse distribution.The problem of water shortages restricts the applications of wet coal beneficiation technologies in drought regions.The present situation highlights the significance and urgency of developing dry beneficiation technologies of coal.Besides,other countries that produce large amounts of coal also encounter serious problem of lack of water for coal beneficiation,such as American,Australia,Canada,South Africa,Turkey and India.Thus,dry coal beneficiation becomes the research hot-points in the field of coal cleaning worldwide in recent years.This paper systematically reviewed the promising research efforts on dry coal beneficiation reported in literature in last 5 years and discussed the progress in developments of dry coal beneficiation worldwide.Finally,we also elaborated the prospects and the challenges of the development of dry coal beneficiation.
基金the National Natural Science Fundation of China(21776213)Natural Science Fund of Tianjin(19JCYBJC19700)for financial support。
文摘Carbonic anhydrase(CA)as a typical metalloenzyme in biological system can accelerate the hydration/dehydration of carbon dioxide(CO2,the major components of greenhouse gases),which performer with high selectivity,environmental friendliness and superior efficiency.However,the free form of CA is quite expensive(~RMB 3000/100 mg),unstable,and non-reusable as the free form of CA is not easy for recovery from the reaction environment,which severely limits its large-scale industrial applications.The immobilization may solve these problems at the same time.In this context,many efforts have been devoted to improving the chemical and thermal stabilities of CA through immobilization strategy.Very recently,a wide range of available inorganic,organic and hybrid compounds have been explored as carrier materials for CA immobilization,which could not only improve the tolerance of CA in hazardous environments,but also improve the efficiency and recovery to reduce the cost of large-scale application of CA.Several excellent reviews about immobilization methods and application potential of CA have been published.By contrast,in our review,we stressed on the way to better retain the biocatalytic activity of immobilized CA system based on different carrier materials and to solve the problems facing in practical operations well.The concluding remarks are presented with a perspective on constructing efficient CO2 conversion systems through rational combining CA and advanced carrier materials.
基金Supported by the Project funded by China Postdoctoral Science Foundation(2016M590191)the Key Basic Research Items in Application Basic Research Program of Hebei Province(16964502D)
文摘Reactive dividing wall column(RDWC) is a highly integrated unit which combines reaction distillation(RD) with dividing wall column separation technology into one shell, and it realized the chemical reaction and the separation of multiple product fractions simultaneously. In this paper, the reaction of esterification with acetic acid and ethanol to produce ethyl acetate was used as the research system, experiments and simulations of the RDWC were carried out. This system in the traditional process mostly used the homogeneous catalyst(e.g. sulfuric acid). However, in view of the corrosion of the equipment caused by the acidity of the catalyst, we used the heterogeneous catalysts – iron exchange resins – Amberlyst15 and proposed a novel catalyst loading method. Firstly,the reliability of the model of the simulation was verified by the experimental study on the change of liquid split ratio and reflux ratio. After that, the four-column model was established in Aspen Plus to analyze the effects of the amount of azeotropic agent, reflux ratio and acetic acid concentration. Finally, for a fair comparison, the economic analysis was conducted between traditional RD column and RDWC. The results showed that RDWC can save34.7% of total operating costs and 18.5% of TAC.
基金supported by the National Natural Science Foundation of China(No.12104057)the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110895)+5 种基金the State Key Laboratory for Mechanical Behavior of Materials(No.20202209)the State Key Laboratory of Advanced Metals and Materials(No.2021-Z02)the Open Project of State Key Laboratory of Advanced Special SteelShanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS 2021-08)the Science and Technology Commission of Shanghai Municipality(Nos.19DZ2270200 and 20511107700)the Major Engineering Materials Service Safety Research Evaluation Facility National Major Science and Technology Infrastructure Open Project Fund。
文摘Multi-principal element alloys exhibit excellent physical,chemical and mechanical properties,and they are used as novel structural materials for potential applications in nuclear energy,hydrogen energy,and petrochemical fields.However,exposing components made of the alloys to service conditions related to the mentioned applications may induce hydrogen embrittlement(HE)as one of the typical failure mechanisms.In this review,we report and summarize the progress in understanding HE in multi-principal element alloys,with a particular focus on high-entropy alloys(HEAs).The review focuses on four aspects:(1)hydrogen migration behavior(hydrogen dissolution,hydrogen diffusion,and hydrogen traps);(2)factors affecting HE(hydrogen concentration,alloy elements and microstructure);(3)tensile mechanical properties in the presence of hydrogen and micro-damage HE mechanisms;(4)the design concept for preventing hydrogen-induced mechanical degradation.The differences in the HE behavior and failure mechanisms between HEAs and traditional alloys are compared and discussed.Moreover,specific research directions for further investigation of fundamental HE issues and a strategy for a simultaneous improvement in strength and HE resistance are identified.
基金This work was supported by the National Key Research and Development Program of China(2017YFA0206803)the National Natural Science Foundation of China(21878315)+3 种基金the Key Programs of the Chinese Academy of Sciences(KFZD-SW-413)the Key Programs of Innovation Academy for Green Manufacture,CAS(IAGM2020C17)K.C.Wong Education Foundation(No.GJTD-2018-04)the Major Program of National Natural Science Foundation of China(21890762).
文摘Lanthanum-containing(LaX)and cerium-containing X zeolites(CeX)were prepared by a doubleexchange,double-calcination method.By changing the calcination atmospheres between nitrogen and air,the Ce^(IV) contents in CeX zeolites were adjusted and their impacts on physicochemical properties and catalytic performance in isobutane alkylation were established.The crystallinity of CeX zeolite was found to be negatively correlated with the Ce^(IV) content.This i s believed to be due to the water formed during the oxidation of Ce^(III),which facilitates the framework dealumination.As a consequence,calcining in air resulted in a great elimination of strong Brønsted acid sites while under nitrogen protection,this phenomenon was mostly hindered and the sample’s acidity was preserved.When tested in a continuously flowed slurry reactor,the catalyst lifetime for isobutane alkylation was found to be linearly related to the strong Brønsted acid concentration.In addition,Ce^(3+)was found more benefit for the hydride transfer compared with La^(3+),which is ascribed to the stronger polarization effect on the CH bond of isobutane.Moreover,the decline of hydride transfer activity can be slowed down by the catalytic cracking of the bulky molecules.Based on the product distribution,a new catalytic cycle of dimethylhexanes(DMHs)involving a direct formation of isobutene rather than tert-butyl carbocation was proposed in isobutane alkylation.
文摘Experiments were made for the adsorption of CO2 and N2 on typical adsorbents to investigate the effects of porous structure and surface affinity of adsorbents as well as those of adsorption temperature and pressure that might cause the variation of adsorption mechanism. It is shown that polar surface tends to enlarge the adsorption difference between CO2 and N2, and the difference is more sensitive to temperature than the adsorbents with non-polar surface. The adsorbents with non-polar surface are not much sensitive to the effect of water vapor, though the water vapor interferes the separation remarkably. The separation coefficient linearly increases with the micro- pore volume per unit surface area of activated carbons, but no rule is shown on mesoporous silicon materials. The function of adsorption mechanism on the separation is not as much as expected.
基金support the National HighTech Research and Development Program of China (No.2011AA03A405)
文摘FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen temperature-programmed reduction （H2-TPR） techniques. The dynamic oxygen storage capacity （DOSC） was investigated by mass spectrometry with CO/O2 transient pulses. The powder XRD data following Rietveld refinement revealed that the solubility limit of iron oxides in the CeO2 was 5 mol% based on Fe/（Ce＋Fe）. The lattice parameters experienced a decrease followed by an increase due to the influence of the maximum solubility limit of iron oxides in the CeO2. TPR analysis revealed that Fe introduction into ceria strongly modified the textual and structural properties, which influenced the oxygen handling properties. DOSC results revealed that Ce-based materials containing Fe oxides with multiple valences contribute to the majority of DOSC. The kinetic analysis indicated that the calculated apparent kinetic parameters obey the compensation effect. The three-way catalytic performance for Pd-only catalysts based on the Fe doping support exhibited the redundant iron species separated out of the CeO2 and interacted with the ceria and Pd species on the surface, which seriously influenced the catalytic properties, especially after hydrothermal aging treatment.
基金supported by the National Natural Science Foundation of China(No.51972310)the Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences(CAS)+1 种基金the Youth Innovation Promotion Association,CAS(No.2011152)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)(No.U1501501).
文摘Noble nanometals are of significance in both scientific interest and technological applications,which are usually obtained by conventional wet-chemical synthesis.Organic surfactants are always used in the synthesis to prevent unexpected overgrowth and aggregation of noble nanometals.However,the surfactants are hard to remove and may interfere with plasmonic and catalytic studies,remaining surfactant-free synthesis of noble nanometals a challenge.Herein,we report an approach to epitaxial growth of sizecontrolled noble nanometals on MXenes.As piloted by density functional theory calculations,along with work function experimental determination,kinetic and spectroscopic studies,epitaxial growth of noble nanometals is initiated via a mechanism that involves an in situ redox reaction.In the redox,MXenes as two-dimensional solid reductants whose work functions are compatible with the reduction potentials of noble metal cations,enable spontaneous donation of electrons from the MXenes to noble metal cations and reduce the cations into nanoscale metallic metals on the outmost surface of MXenes.Neither surfactants nor external reductants are used during the whole synthesis process,which addresses a long-standing interference issue of surfactant and external reductant in the conventional wet-chemical synthesis.Moreover,the MXenes induced noble nanometals are size-controlled.Impressively,noble nanometals firmly anchored on MXenes exhibit excellent performance towards surface enhanced Raman scattering.Our developed strategy will promote the nanostructure-controlled synthesis of noble nanometals,offering new opportunities to further improve advanced functional properties towards practical applications.
基金the National Natural Science Foundation of China (Nos. 51774283, 51174203)the Major International (Regional) Joint Research Project of NSFC (No. 51620105001) for the financial supports
文摘The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration frequency and amplitude, and gas velocity on these characteristics were considered. The average size, average density, size deviation coefficient, and density deviation coefficient were used to identify lignite size and density. The separation efficiency was adopted to evaluate the segregation performance,and the segregation mechanisms were explored. The results show that ε(size,max) of heterogeneous multisize-component lignite with K_(size) = 65% reaches 80% at f= 20 Hz, A = 5 mm, and N =(1,3). ε_(density,max) Of heterogeneous multi-density-component lignite with K_(density)= 25% reaches 50% at f = 15 Hz, A = 5 mm,and N =(1,1.5). The density segregations of 1-3 and 3-6 mm multi-component mixtures are remarkable,ε_(density,max)= 42% and 31% at f= 14 and 16 Hz, and A = 3 and 5 mm, respectively. The size segregation of 1-6 mm multi-component mixture is prominent and ε_(size,max)= 55% at f= 15 Hz, A = 5 mm. The mediumsized mixture with a narrow size distribution at low frequency is favorable for density segregation,and a mixture with a wider size distribution at high frequency is most favorable for size segregation.Precise control of gas flow and vibration as well as optimal design of the fluidized bed can improve the performance of segregation in the vibrated gas-fluidized bed.
