The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy.Ammonia borane(AB)has regarded as a competitive candidate for ...The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy.Ammonia borane(AB)has regarded as a competitive candidate for chemical hydrogen storage.However,developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge.Herein,cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure,and function as hydrogen evolution photocatalysts.Impressively,the Co_(2)P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min^(-1),outperforming most of the noble-metal-free catalysts reported to date.This remarkable performance is attributed to its desired nanosheets structure,featuring with high specific surface area,abundant exposed active sites,and short charge diffusion paths.Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond.展开更多
This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and...This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.展开更多
Solid-state polymer electrolytes(SPEs)have attracted increasing attention due to good interfacial contact,light weight,and easy manufacturing.However,the practical application of SPEs such as the most widely studied p...Solid-state polymer electrolytes(SPEs)have attracted increasing attention due to good interfacial contact,light weight,and easy manufacturing.However,the practical application of SPEs such as the most widely studied poly(ethylene oxide)(PEO)in high-energy solid polymer batteries is still challenging,and the reasons are yet elusive.Here,it is found that the mismatch between PEO and 4.2 V-class cathodes is beyond the limited electrochemical window of PEO in the solid Li Ni_(1/3)Mn_(1/3)Co_(1/3)O_(2)(NMC)-PEO batteries.The initial oxidation of PEO initiates remarkable surface reconstruction of NMC grains in solid batteries that are different from the situation in liquid electrolytes.Well-aligned nanovoids are observed in NMC grains during the diffusion of surface reconstruction layers towards the bulk in solid batteries.The substantial interphasial degradation,therefore,blocks smooth Li+transport across the NMC-PEO interface and causes performance degradation.A thin yet effective Li F-containing protection layer on NMC can effectively stabilize the NMC-PEO interface with a greatly improved lifespan of NMC|PEO|Li batteries.This work deepens the understanding of degradations in high-voltage solid-state polymer batteries.展开更多
Understanding the relationship between the chemical composition and pyrolysis performance of endothermic hydrocarbon fuel(EHF) is of great significance for the design and optimization of advanced EHFs. In this work, t...Understanding the relationship between the chemical composition and pyrolysis performance of endothermic hydrocarbon fuel(EHF) is of great significance for the design and optimization of advanced EHFs. In this work, the effect of deep hydrogenation on the pyrolysis of commercial RP-3 is investigated.Fuels with different hydrogenation degrees were obtained by the partially and completely catalytic hydrogenation and their pyrolysis performances were investigated using an apparatus equipped with an electrically heated tubular reactor. The results show that with the increase of hydrogenation degree, fuel conversion almost remains constant during the pyrolysis process(500-650°C, 4 MPa);however, the heat sink increases slightly, and the anti-coking performance significantly improves, which are highly related to their H/C ratios. Detailed characterisations reveal that the difference of the pyrolysis performance can be ascribed to the content of aromatics and cycloalkanes: the former are prone to initiate secondary reactions to form coking precursors, while the latter could act as the hydrogen donor and release hydrogen, which will terminate the radical propagation reactions and suppress the coke deposition. This work should provide the guidance for upgrading EHFs by modulating the composition of EHFs.展开更多
Methane steam reforming is the main hydrogen production method in the industry. The product of methane steam reforming contains H2, CH4, CO and CO2 and is then purified by pressure swing adsorption(PSA) technology. In...Methane steam reforming is the main hydrogen production method in the industry. The product of methane steam reforming contains H2, CH4, CO and CO2 and is then purified by pressure swing adsorption(PSA) technology. In this study, a layered two-bed PSA process was designed theoretically to purify H2 from methane steam reforming off gas. The effects of adsorption pressure, adsorption time and purgeto-feed ratio(P/F ratio) on process performance were investigated to design a PSA process with more than99.95% purity and 80% recovery. Since the feed composition of the PSA process changes with the upstream process, the effect of the feed composition on the process performance was discussed as well.The result showed that the increase of CH4 concentration, which was the weakest adsorbate, would have a negative impact on product purity.展开更多
Supported metal catalysts play a vital role in the chemical industry, and the metal-support interaction is an important property of the catalyst. However, in the traditional impregnation method, it is difficult to obt...Supported metal catalysts play a vital role in the chemical industry, and the metal-support interaction is an important property of the catalyst. However, in the traditional impregnation method, it is difficult to obtain sufficient metal-support interactions owing to the mobility of the metal precursor during evaporation drying. Here, freeze drying is applied during impregnation instead of evaporation drying for enhancing the metal-support interactions. 57 Fe ZSM-5 was chosen as a representative catalyst. A quantitative analysis was conducted based on Mossbauer spectroscopy. Compared with traditional evaporation-drying catalyst, freeze-drying catalyst has stronger metal-support interactions. In addition, more iron species are confined in the channel and smaller metal sizes and less diversity are obtained. The compositional change is also proved because of the superior performance of the freeze-drying catalyst during N2O decomposition. This method can be extended to other supported metal catalysts prepared through an impregnation method, which can be used to tune the metal-support interactions and metal sizes.展开更多
Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we ...Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.展开更多
Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membra...Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membrane layer, which usually requires complex surface modification or seeding. Herein, we demonstrate that a dual-layer asymmetric polymer support prepared by a simple spinning process is a good candidate for the preparation of ZIF-8 membrane. The inner layer of the support is an organic hollow fiber(PES) with finger-like pores, and the outer layer is a ZnO-PES composite layer with finger-like pores also. The ZnO-PES composite layer is expected to contain uniform ZnO crystals in the polymer matrix, i.e., the ZnO particles in the skin layer of the support are not easy to fall off. Under the induction of ZnO particles in the outer layers, continuous ZIF-8 membranes can be prepared by single in-situ crystallization, showing good adhesion to the supports. The obtained ZIF-8 membranes show a H_(2) permeance of 8.7 × 10^(-8)mol·m^(-2)·s^(-1)·Pa^(-1) with a H_(2)/N_(2) ideal separation selectivity of 18.0. The design and preparation of this dual-layer polymer support is expected to promote the large-scale application of MOF membranes on polymer supports.展开更多
Iron-containing zeolites play an important role in the selective oxidation of methane to oxygenates by nitrous oxide.A solid-state ion exchange method is adopted to prepare Fe-MOR zeolite catalysts with different amou...Iron-containing zeolites play an important role in the selective oxidation of methane to oxygenates by nitrous oxide.A solid-state ion exchange method is adopted to prepare Fe-MOR zeolite catalysts with different amounts of extra-framework Al.EPR spectra and UV-vis spectra show that the percentage of iron ions in tetrahedral or octahedral coordination increases while those of clustered Fe species decrease by the addition of extra-framework Al species.Nitrous oxide titration reveals that more active Fe centers are formed,which promote the nitrous oxide consumption.The number of active centers in the catalyst with the introduction of extra-framework Al is about four times that of the catalyst without the addition of extra-framework Al.Due to this,there is an increase in the methane conversion,total selectivity and yield of oxygenates.展开更多
Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus....Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus.A comparison of model results with industrial data and previously reported results showed that the model can predict the process kinetics more accurately.In addition,the validated model was used to study the effects of different process variables,including coil outlet temperature(COT),steam-to-ethane ratio and residence time on ethane conversion,ethylene selectivity,products yields,and coking rate.Finally,steady-state optimization was conducted to the operation of industrial reactor.The COT and steam-to-ethane ratio were taken as decision variables to maximize the annual operational profit.展开更多
Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-h...Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.展开更多
In this work,a degradable polyurethane composed of caprolactone(CL)and L-Lactide(LLA)as soft segments,and 4,40-methylenebis(cyclohexyl isocyanate)(H12 MDI)and polytetramethylene ether glycol(PTMEG)as hard segments,was...In this work,a degradable polyurethane composed of caprolactone(CL)and L-Lactide(LLA)as soft segments,and 4,40-methylenebis(cyclohexyl isocyanate)(H12 MDI)and polytetramethylene ether glycol(PTMEG)as hard segments,was prepared.Hydrolytic degradation experiment revealed that the degradable polyurethane(PU)could be degraded in artificial seawater.It also showed that caprolactone-copolyurethane(CL-PU)copolymer with higher crystallinity degraded much slower in artificial seawater.However,the introduction of LLA resulted in an increase in the hydrophilicity and reduction in the crystallinity of degradable PU,as demonstrated by the contact angle analysis.The result of the scanning electron microscope showed that the surface of degradable PU renewed under static condition.Moreover,degradable PU was able to be used as a carrier,and it controlled the release rate of 4,5-dichloro-2-octyl-isothiazolone(DCOIT).The anti-diatom(Navicula incerta)test demonstrated that the(caprolactone-co-L-lactide)-co-polyurethane 4(CL/LAx-PU4)with DCOIT contents prevented the adhesion of diatom Navicula incerta(88.37%reduction)due to their self-polishing and the release of antifoulants.Therefore,the degradable PU consisted of CL,LLA,and DCOIT could be a durable resin with good antifouling activity for the application in the marine anti-biofouling field.展开更多
This work first investigated the detection of slags,slag pool liquid level,and slag accumulation height in laboratory scale based on acoustic emission(AE)detection,and further tried the feasibility of this method in a...This work first investigated the detection of slags,slag pool liquid level,and slag accumulation height in laboratory scale based on acoustic emission(AE)detection,and further tried the feasibility of this method in an industrial scale coal gasifier.Results show that the energy and variance of acoustic signals can realize the accurate detection of large slag(criterion:E>1.5 E0,S>1.2 S0),and the average relative error is only 0.28%.The acoustic energy in the frequency range of 20–40 k Hz is defined as the characteristic energy,which can realize the accurate detection of slag accumulation height and slag pool liquid level,and the average relative error is only 3.94%.Furthermore,AE detection also realize accurate detection of large slag in an industrial scale gasifier and the acoustic signals at slag screen can be used to realize the early warning of the slag collapse(5 h earlier).展开更多
Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through...Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.展开更多
The aminolysis of ethyl acetate was promoted significantly via continuous reaction in a tubular reactor.Npropylacetamide was thus synthesized without presence of solvent and catalyst.The optimum conditions were obtain...The aminolysis of ethyl acetate was promoted significantly via continuous reaction in a tubular reactor.Npropylacetamide was thus synthesized without presence of solvent and catalyst.The optimum conditions were obtained as follows:the reaction temperature is 218℃,the reaction pressure is 3.5 MPa,the molar ratio(ethyl acetate:N-propylamine)is 1:1,and the residence time is 350 min.Accordingly,the conversion of ethyl acetate is up to94.8%.Furthermore,the kinetics of the rapid reaction stage(when the conversion of ethyl acetate is 20%-80%)can be expressed as Ink=-4629.441/T+2.1366,and the apparent activation energy is Ea=38489 J·mol-1.展开更多
Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold lo...Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated.The catalysts are characterized by CO_(2)-TPD,EDS,XPS,STEM and XRD techniques.Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion,resulting in a higher catalytic performance,and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution.The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst,and the optimum Mg/Al molar ratio is 0.1–0.2.This study underlines the importance of engineering support particle size,concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.展开更多
Developing effective iron-incorporated zeolites and determining their active centers for the direct oxidation of CH_4 to oxygenates have remained challenging topics so far.In this paper,we successfully prepare the hig...Developing effective iron-incorporated zeolites and determining their active centers for the direct oxidation of CH_4 to oxygenates have remained challenging topics so far.In this paper,we successfully prepare the highly-dispersed iron supported Y zeolites by a facile solid-state ion-exchange method with ferrocene,which was conducted under water-free conditions followed by a series of calcination.Moreover,extra-framework dinuclear Fe^(2+)complexes are identified as so-called activeα-iron sites on zeolites.ICP-OES,N_2 adsorption–desorption test,X-ray diffraction,solid-state^(27)Al NMR,N_2O titration,TEM,EPR and^(57)Fe M?ssbauer spectra were carried out to characterize properties of sample structure,acid sites,as well as the supported iron species.Characterization results indicate that high-temperature treatments have no effect on the typical structure feature of zeolites.Compared with catalysts synthesized by conventional impregnation,the samples prepared by the facile approach possess abundant dinuclear Fe^(2+)complexes but no Fe_2O_3 bulks and show weak acidity.These lead to a higher oxygenate selectivity in CH_4 oxidation to oxygenates.Remarkably,the oxygenate(HCHO and CH_3OH)selectivity of 6.5% at 375°C can be eventually obtained.展开更多
Continuous preparation of pyromellitic dianhydride(PMDA) from durene has been studied using a fixedbed reactor. The reaction was performed using a phosphorus-vanadium-titanium ternary catalyst.Relatively high selectiv...Continuous preparation of pyromellitic dianhydride(PMDA) from durene has been studied using a fixedbed reactor. The reaction was performed using a phosphorus-vanadium-titanium ternary catalyst.Relatively high selectivity and yield of PMDA was obtained. The in-situ characterization was combined with theoretical calculation to reveal the reaction mechanisms, and the remarkable doping effect was discussed.展开更多
Antioxidants addition is believed as a facile and effective way to improve jet fuel thermal oxidation stability.However,amine antioxidants,as one of the most important antioxidants,have not received sufficient attenti...Antioxidants addition is believed as a facile and effective way to improve jet fuel thermal oxidation stability.However,amine antioxidants,as one of the most important antioxidants,have not received sufficient attention in the field of jet fuel autoxidation yet.Herein,the inhibition efficiency and mechanism of decane and exo-tetrahydrodicyclopentadiene(THDCPD)oxidation by di-4-tert-butylphenylamine(diarylamine)was experimentally and theoretically investigated.The results show that diarylamine can significantly inhibit decane oxidation but is less efficient for THDCPD oxidation,which is attributed to the higher energy barrier of retro-carbonyl-ene reaction(rate-determining step)in THDCPD than that in decane during diarylamine regeneration.However,the addition of diarylamine will cause undesirable color change after accelerated oxidation and produce slightly more deposits during high-temperature thermal oxidative stress for both decane and THDCPD.The results provide significant implications for the future design of effective antioxidant additives for high-performance jet fuel.展开更多
Difluoromethane is typically produced vialiquid-phase fluorination as performed in a batch reactor.However,this process suffers from some problems,e.g.,severe corrosion of the reactor,high safety risk,and the regenera...Difluoromethane is typically produced vialiquid-phase fluorination as performed in a batch reactor.However,this process suffers from some problems,e.g.,severe corrosion of the reactor,high safety risk,and the regeneration of the catalyst.In this paper,a flow process as performed in the tubular reactor was designed.The optimum conditions for continuous synthesis of difluoromethane were obtained as follows:the reaction temperature was 100℃,the molar ratio of dichloromethane to hydrogen fluoride was 1.6:1 and the reaction time was 300 s.The operation of the cyclic process was stable for 24 h with the conversion per pass of hydrogen fluoride up to 16.2%.The unreacted raw materials were easily reused.The deactivation of the common catalyst,antimony pentachloride,was investigated by catalyst concentration curve and XPS analysis.The approach proposed in this work is proven to be safe,efficient and low amount of catalyst.展开更多
基金supported by the National Natural Science Foundation of China(22108238,21878259)the Zhejiang Provincial Natural Science Foundation of China(LR18B060001)+5 种基金Anhui Provincial Natural Science Founda-tion(1908085QB68)the Natural Science Foundation of the Anhui Higher Education Institutions of China(KJ2020A0275)Major Science and Technology Project of Anhui Province(201903a05020055)Foundation of Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology(ZJKL-ACEMT-1802)China Postdoctoral Science Foundation(2019M662060,2020T130580)Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology(BM2012110).
文摘The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy.Ammonia borane(AB)has regarded as a competitive candidate for chemical hydrogen storage.However,developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge.Herein,cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure,and function as hydrogen evolution photocatalysts.Impressively,the Co_(2)P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min^(-1),outperforming most of the noble-metal-free catalysts reported to date.This remarkable performance is attributed to its desired nanosheets structure,featuring with high specific surface area,abundant exposed active sites,and short charge diffusion paths.Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond.
基金support and encouragement of the Joint Funds of the National Natural Science Foundation of China(No.U21B2095)the Major Research Project of National Natural Science Foundation of China(No.91834303).
文摘This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.
基金supported by the National Natural Science Foundation of China (U21A2075, 22179117)the Fujian Science & Technology Innovation Laboratory for Energy Devices of China (21CLAB) (21C-OP-202107)the Program of Zhejiang University and Program of State Key Laboratory of Clean Energy Utilization at Zhejiang (ZJUCEU2020005)
文摘Solid-state polymer electrolytes(SPEs)have attracted increasing attention due to good interfacial contact,light weight,and easy manufacturing.However,the practical application of SPEs such as the most widely studied poly(ethylene oxide)(PEO)in high-energy solid polymer batteries is still challenging,and the reasons are yet elusive.Here,it is found that the mismatch between PEO and 4.2 V-class cathodes is beyond the limited electrochemical window of PEO in the solid Li Ni_(1/3)Mn_(1/3)Co_(1/3)O_(2)(NMC)-PEO batteries.The initial oxidation of PEO initiates remarkable surface reconstruction of NMC grains in solid batteries that are different from the situation in liquid electrolytes.Well-aligned nanovoids are observed in NMC grains during the diffusion of surface reconstruction layers towards the bulk in solid batteries.The substantial interphasial degradation,therefore,blocks smooth Li+transport across the NMC-PEO interface and causes performance degradation.A thin yet effective Li F-containing protection layer on NMC can effectively stabilize the NMC-PEO interface with a greatly improved lifespan of NMC|PEO|Li batteries.This work deepens the understanding of degradations in high-voltage solid-state polymer batteries.
基金support from National Key Research and Development Program of China(2021YFC2103701)the National Postdoctoral Program of China(GZB20230630)the National Natural Science Foundation of China(22208295).
文摘Understanding the relationship between the chemical composition and pyrolysis performance of endothermic hydrocarbon fuel(EHF) is of great significance for the design and optimization of advanced EHFs. In this work, the effect of deep hydrogenation on the pyrolysis of commercial RP-3 is investigated.Fuels with different hydrogenation degrees were obtained by the partially and completely catalytic hydrogenation and their pyrolysis performances were investigated using an apparatus equipped with an electrically heated tubular reactor. The results show that with the increase of hydrogenation degree, fuel conversion almost remains constant during the pyrolysis process(500-650°C, 4 MPa);however, the heat sink increases slightly, and the anti-coking performance significantly improves, which are highly related to their H/C ratios. Detailed characterisations reveal that the difference of the pyrolysis performance can be ascribed to the content of aromatics and cycloalkanes: the former are prone to initiate secondary reactions to form coking precursors, while the latter could act as the hydrogen donor and release hydrogen, which will terminate the radical propagation reactions and suppress the coke deposition. This work should provide the guidance for upgrading EHFs by modulating the composition of EHFs.
基金The financial support from the project of National Natural Science Foundation of China(21822809&61590925)the National Science Fund for Distinguished Young Scholars(21525627)
文摘Methane steam reforming is the main hydrogen production method in the industry. The product of methane steam reforming contains H2, CH4, CO and CO2 and is then purified by pressure swing adsorption(PSA) technology. In this study, a layered two-bed PSA process was designed theoretically to purify H2 from methane steam reforming off gas. The effects of adsorption pressure, adsorption time and purgeto-feed ratio(P/F ratio) on process performance were investigated to design a PSA process with more than99.95% purity and 80% recovery. Since the feed composition of the PSA process changes with the upstream process, the effect of the feed composition on the process performance was discussed as well.The result showed that the increase of CH4 concentration, which was the weakest adsorbate, would have a negative impact on product purity.
基金supported by the National Key R&D Program of China(2016YFA0202900)the National Natural Science Foundation of China(21622606)+1 种基金Zhejiang Provincial Natural Science Foundation of China(LR18B060001)the Fundamental Research Funds for the Central Universities~~
文摘Supported metal catalysts play a vital role in the chemical industry, and the metal-support interaction is an important property of the catalyst. However, in the traditional impregnation method, it is difficult to obtain sufficient metal-support interactions owing to the mobility of the metal precursor during evaporation drying. Here, freeze drying is applied during impregnation instead of evaporation drying for enhancing the metal-support interactions. 57 Fe ZSM-5 was chosen as a representative catalyst. A quantitative analysis was conducted based on Mossbauer spectroscopy. Compared with traditional evaporation-drying catalyst, freeze-drying catalyst has stronger metal-support interactions. In addition, more iron species are confined in the channel and smaller metal sizes and less diversity are obtained. The compositional change is also proved because of the superior performance of the freeze-drying catalyst during N2O decomposition. This method can be extended to other supported metal catalysts prepared through an impregnation method, which can be used to tune the metal-support interactions and metal sizes.
基金Supported by the National Natural Science Foundation of China(21676238)
文摘Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.
基金supported by the National Natural Science Foundation of China (21978253)the Fundamental Research Funds for the Central Universities (226-2022-00020, 226-2022-00055)。
文摘Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membrane layer, which usually requires complex surface modification or seeding. Herein, we demonstrate that a dual-layer asymmetric polymer support prepared by a simple spinning process is a good candidate for the preparation of ZIF-8 membrane. The inner layer of the support is an organic hollow fiber(PES) with finger-like pores, and the outer layer is a ZnO-PES composite layer with finger-like pores also. The ZnO-PES composite layer is expected to contain uniform ZnO crystals in the polymer matrix, i.e., the ZnO particles in the skin layer of the support are not easy to fall off. Under the induction of ZnO particles in the outer layers, continuous ZIF-8 membranes can be prepared by single in-situ crystallization, showing good adhesion to the supports. The obtained ZIF-8 membranes show a H_(2) permeance of 8.7 × 10^(-8)mol·m^(-2)·s^(-1)·Pa^(-1) with a H_(2)/N_(2) ideal separation selectivity of 18.0. The design and preparation of this dual-layer polymer support is expected to promote the large-scale application of MOF membranes on polymer supports.
基金This research was supported by the Zhejiang Provincial Natural Science Foundation of China(LR18B060001)Basic Research Project of Sinopec Group(415025)the Fundamental Research Funds for the Central Universities.
文摘Iron-containing zeolites play an important role in the selective oxidation of methane to oxygenates by nitrous oxide.A solid-state ion exchange method is adopted to prepare Fe-MOR zeolite catalysts with different amounts of extra-framework Al.EPR spectra and UV-vis spectra show that the percentage of iron ions in tetrahedral or octahedral coordination increases while those of clustered Fe species decrease by the addition of extra-framework Al species.Nitrous oxide titration reveals that more active Fe centers are formed,which promote the nitrous oxide consumption.The number of active centers in the catalyst with the introduction of extra-framework Al is about four times that of the catalyst without the addition of extra-framework Al.Due to this,there is an increase in the methane conversion,total selectivity and yield of oxygenates.
基金The financial support provided by the Project of National Natural Science Foundation of China(21822809&21978256)the Fundamental Research Funds for the Central Universitiesthe Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(Grant No.2018-K23)are gratefully acknowledged.
文摘Ethane steam cracking process in an industrial reactor was investigated.An one-demsional(1D)steady-state model was developed firstly by using an improved molecular reaction scheme and was then simulated in Aspen Plus.A comparison of model results with industrial data and previously reported results showed that the model can predict the process kinetics more accurately.In addition,the validated model was used to study the effects of different process variables,including coil outlet temperature(COT),steam-to-ethane ratio and residence time on ethane conversion,ethylene selectivity,products yields,and coking rate.Finally,steady-state optimization was conducted to the operation of industrial reactor.The COT and steam-to-ethane ratio were taken as decision variables to maximize the annual operational profit.
基金The support from the National Natural Science Foundation of China(22278353)is greatly appreciated。
文摘Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.
基金supported by the National Natural Science Foundation of China(21776249,21878267,21576236)。
文摘In this work,a degradable polyurethane composed of caprolactone(CL)and L-Lactide(LLA)as soft segments,and 4,40-methylenebis(cyclohexyl isocyanate)(H12 MDI)and polytetramethylene ether glycol(PTMEG)as hard segments,was prepared.Hydrolytic degradation experiment revealed that the degradable polyurethane(PU)could be degraded in artificial seawater.It also showed that caprolactone-copolyurethane(CL-PU)copolymer with higher crystallinity degraded much slower in artificial seawater.However,the introduction of LLA resulted in an increase in the hydrophilicity and reduction in the crystallinity of degradable PU,as demonstrated by the contact angle analysis.The result of the scanning electron microscope showed that the surface of degradable PU renewed under static condition.Moreover,degradable PU was able to be used as a carrier,and it controlled the release rate of 4,5-dichloro-2-octyl-isothiazolone(DCOIT).The anti-diatom(Navicula incerta)test demonstrated that the(caprolactone-co-L-lactide)-co-polyurethane 4(CL/LAx-PU4)with DCOIT contents prevented the adhesion of diatom Navicula incerta(88.37%reduction)due to their self-polishing and the release of antifoulants.Therefore,the degradable PU consisted of CL,LLA,and DCOIT could be a durable resin with good antifouling activity for the application in the marine anti-biofouling field.
基金the support and encouragement of The National Science Fund for Distinguished Young(21525627)the Science Fund for Creative Research Groups of National Natural Science Foundation of China(61621002)。
文摘This work first investigated the detection of slags,slag pool liquid level,and slag accumulation height in laboratory scale based on acoustic emission(AE)detection,and further tried the feasibility of this method in an industrial scale coal gasifier.Results show that the energy and variance of acoustic signals can realize the accurate detection of large slag(criterion:E>1.5 E0,S>1.2 S0),and the average relative error is only 0.28%.The acoustic energy in the frequency range of 20–40 k Hz is defined as the characteristic energy,which can realize the accurate detection of slag accumulation height and slag pool liquid level,and the average relative error is only 3.94%.Furthermore,AE detection also realize accurate detection of large slag in an industrial scale gasifier and the acoustic signals at slag screen can be used to realize the early warning of the slag collapse(5 h earlier).
文摘Catalytic co-cracking of Fischer–Tropsch(FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins,monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.
基金financial support from the National Natural Science Foundation of China(21476194)the National Key Research and Development Program of China(2016YFB0301800).
文摘The aminolysis of ethyl acetate was promoted significantly via continuous reaction in a tubular reactor.Npropylacetamide was thus synthesized without presence of solvent and catalyst.The optimum conditions were obtained as follows:the reaction temperature is 218℃,the reaction pressure is 3.5 MPa,the molar ratio(ethyl acetate:N-propylamine)is 1:1,and the residence time is 350 min.Accordingly,the conversion of ethyl acetate is up to94.8%.Furthermore,the kinetics of the rapid reaction stage(when the conversion of ethyl acetate is 20%-80%)can be expressed as Ink=-4629.441/T+2.1366,and the apparent activation energy is Ea=38489 J·mol-1.
基金Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050269)the Fundamental Research Funds for the Central Universities(226-2023-00085,226-2023-00057).
文摘Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated.The catalysts are characterized by CO_(2)-TPD,EDS,XPS,STEM and XRD techniques.Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion,resulting in a higher catalytic performance,and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution.The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst,and the optimum Mg/Al molar ratio is 0.1–0.2.This study underlines the importance of engineering support particle size,concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.
基金Support by the National Key R&D Program of China(2016YFA0202900)the National Natural Science Foundation of China(21622606)+2 种基金the Natural Science Foundation of Zhejiang Province(LR18B060001)Basic Research Project of Sinopec Group(415025)the Fundamental Research Funds for the Central Universities
文摘Developing effective iron-incorporated zeolites and determining their active centers for the direct oxidation of CH_4 to oxygenates have remained challenging topics so far.In this paper,we successfully prepare the highly-dispersed iron supported Y zeolites by a facile solid-state ion-exchange method with ferrocene,which was conducted under water-free conditions followed by a series of calcination.Moreover,extra-framework dinuclear Fe^(2+)complexes are identified as so-called activeα-iron sites on zeolites.ICP-OES,N_2 adsorption–desorption test,X-ray diffraction,solid-state^(27)Al NMR,N_2O titration,TEM,EPR and^(57)Fe M?ssbauer spectra were carried out to characterize properties of sample structure,acid sites,as well as the supported iron species.Characterization results indicate that high-temperature treatments have no effect on the typical structure feature of zeolites.Compared with catalysts synthesized by conventional impregnation,the samples prepared by the facile approach possess abundant dinuclear Fe^(2+)complexes but no Fe_2O_3 bulks and show weak acidity.These lead to a higher oxygenate selectivity in CH_4 oxidation to oxygenates.Remarkably,the oxygenate(HCHO and CH_3OH)selectivity of 6.5% at 375°C can be eventually obtained.
基金financial support by the National Natural Science Foundation of China (21878265)。
文摘Continuous preparation of pyromellitic dianhydride(PMDA) from durene has been studied using a fixedbed reactor. The reaction was performed using a phosphorus-vanadium-titanium ternary catalyst.Relatively high selectivity and yield of PMDA was obtained. The in-situ characterization was combined with theoretical calculation to reveal the reaction mechanisms, and the remarkable doping effect was discussed.
基金the financial support from the Postdoctoral Science Foundation of China(2021M702810)the Haihe Laboratory of Sustainable Chemical Transformations(CYZC202103)the National Natural Science Foundation of China(21978200 and 22222808)。
文摘Antioxidants addition is believed as a facile and effective way to improve jet fuel thermal oxidation stability.However,amine antioxidants,as one of the most important antioxidants,have not received sufficient attention in the field of jet fuel autoxidation yet.Herein,the inhibition efficiency and mechanism of decane and exo-tetrahydrodicyclopentadiene(THDCPD)oxidation by di-4-tert-butylphenylamine(diarylamine)was experimentally and theoretically investigated.The results show that diarylamine can significantly inhibit decane oxidation but is less efficient for THDCPD oxidation,which is attributed to the higher energy barrier of retro-carbonyl-ene reaction(rate-determining step)in THDCPD than that in decane during diarylamine regeneration.However,the addition of diarylamine will cause undesirable color change after accelerated oxidation and produce slightly more deposits during high-temperature thermal oxidative stress for both decane and THDCPD.The results provide significant implications for the future design of effective antioxidant additives for high-performance jet fuel.
基金financial support from the National Natural Science Foundation of China(21878265,21606104)the National Key Research and Development Program of China(2016YFB0301800)。
文摘Difluoromethane is typically produced vialiquid-phase fluorination as performed in a batch reactor.However,this process suffers from some problems,e.g.,severe corrosion of the reactor,high safety risk,and the regeneration of the catalyst.In this paper,a flow process as performed in the tubular reactor was designed.The optimum conditions for continuous synthesis of difluoromethane were obtained as follows:the reaction temperature was 100℃,the molar ratio of dichloromethane to hydrogen fluoride was 1.6:1 and the reaction time was 300 s.The operation of the cyclic process was stable for 24 h with the conversion per pass of hydrogen fluoride up to 16.2%.The unreacted raw materials were easily reused.The deactivation of the common catalyst,antimony pentachloride,was investigated by catalyst concentration curve and XPS analysis.The approach proposed in this work is proven to be safe,efficient and low amount of catalyst.
