The rheological properties of South China Sea （SCS） crude oil were studied. A group of synthetic long-chain polymers, including octadecyl acrylate-maleic anhydride bidodecyl amide copolymer （VR-D）, octadecyl acryl...The rheological properties of South China Sea （SCS） crude oil were studied. A group of synthetic long-chain polymers, including octadecyl acrylate-maleic anhydride bidodecyl amide copolymer （VR-D）, octadecyl acrylate-maleic anhydride bioctadecyl amide copolymer （VR-O） and octadecyl acrylate-maleic anhydride phenly amide copolymer （VR-A）, were employed to serve as viscosity reducers （VRs）. Their performance was evaluated by both experimental and computational methodologies. The results suggest that the SCS crude oil has low wax content yet high resin and asphaltene contents, which lead to high viscosity through formation of association structures. Additionally, the SCS crude oil appears to be a pseudoplastic fluid showing linear shear stress-shear rate dependence at low temperature. Interestingly, it gradually evolves into a Newtonian fluid with exponential relationship between shear stress and shear rate at higher temperature. Synthetic VRs demonstrate desirable and effective performance on improvement of the rheological properties of SCS crude oil. Upon the introduction of 1000ppm VR-O, which is synthesized by using octadecylamine in the aminolysis reaction, the viscosity of SCS crude oil is decreased by 44.2% at 15 ℃ and 40.2% at 40℃. The computational study suggests significant energy level increase and shear stress decrease for VR-containing crude oil systems.展开更多
Supported Pd catalysts with varied Pd loadings(x=0.5 wt%, 2.0 wt%, 5.0 wt%, 7.5 wt%, 15.0 wt%) were prepared by the incipient wetness impregnation method using a ZnAl_(2)O_(4) spinel support.We found that ZnAl_(2)O_(4...Supported Pd catalysts with varied Pd loadings(x=0.5 wt%, 2.0 wt%, 5.0 wt%, 7.5 wt%, 15.0 wt%) were prepared by the incipient wetness impregnation method using a ZnAl_(2)O_(4) spinel support.We found that ZnAl_(2)O_(4) supported Pd catalysts with low Pd loadings(e.g., 0.5 wt%) are very selective in syngas conversion to methanol and dimethyl-ether(DME).XRD and TEM characterization shows that,after reduction at350℃,PdZnβ phase with Pd:Zn molar ratio of 1:1 is favored to form predominantly on the spinel support at relatively low Pd loadings,i.e.less than 5.0 wt%, while Pd-rich PdZnα alloy phase exists at Pd loadings above 5.0 wt%.A higher reduction temperature such as 500℃ can facilitate the transformation from PdZnα to PdZnβ phase in those catalysts with high Pd loading.We further found that catalysts with predominant PdZnβ phase are selective in the methanol and DME production from syngas,while the presence of PdZnα phase leads to the notable formation of alkanes byproducts,resulting in reduced methanol and DME selectivity.DME formation from dehydration of methanol depends on the acidity of catalysts,which was found to increase with Pd loading,probably due to the formation of isolated Al_(2)O_(3) as a result of Zn migrating from ZnAl_(2)O_(4) spinel phase to form the PdZn phases with Pd.展开更多
Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical,...Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical, through oxidative esterification over Au-based catalysts. Detailed experimental studies showed that Au on amphoteric supports with appropriate strength and balanced ratio of acid and base sites can facilitate the desired oxidative-esterification pathway without accelerating undesired aldol-condensation or Cannizzaro reactions. In particular, hydroxyapatite (with a Ca/P ratio of 1.62) supported Au achieved 87% selectivity to methyl pyruvate at an acetol conversion of 62%.展开更多
This paper reports an experimental study on catalytic conversion of carbon dioxide to methanol, ethanol and acetic acid. Satalysts having different catalytic functions were synthesized and combined in different ways t...This paper reports an experimental study on catalytic conversion of carbon dioxide to methanol, ethanol and acetic acid. Satalysts having different catalytic functions were synthesized and combined in different ways to enhance the selectivity to desired products. The combined catalyst system possessed the following functions： methanol synthesis, Fischer-Tropsch synthesis, water-gas-shift and hydrogenation. Results showed that the methods of integrating these catalytic functions played an important role in achieving the desired product selectivity. We speculate that if methanol synthesis sites were located adjacent to the C--C chain growth sites, the formation rate of C2 oxygenates would be enhanced. The advantage of using a high temperature methanol catalyst PdZnA1 in the combined catalyst system was demonstrated. In the presence of PdZnA1 catalyst, the combined catalyst system was stable at 380 ~C. It was observed that, at high temperature, kinetics favored oxygenate formation. The results implied that the process can be intensified by operating at high temperature using Pd-based methanol synthesis catalyst. Steam reforming of the byproduct organics was demonstrated as a means to provide supplemental hydrogen. Preliminary process design, simulation, and economic analysis of the proposed CO2 conversion process were carded out. Economic analysis indicates how ethanol production cost was affected by the price of CO2 and hydrogen.展开更多
Terpenoids have drawn much attention to scientists in synthesizing high-performance bio-jet fuels due to their ring structures,which feature potential high densities.Here,a facile biphasic catalytic process has been d...Terpenoids have drawn much attention to scientists in synthesizing high-performance bio-jet fuels due to their ring structures,which feature potential high densities.Here,a facile biphasic catalytic process has been developed for the production of high-density tricyclic hydrocarbon biofuels from a monoterpenoid,1,8-cineole,using sulfuric acid(H2SO4)as the homogeneous catalyst.A^100%conversion of 1,8-cineole and a>40%carbon yield of cyclic dimers were achieved at 100℃within two hours.The mechanism for the acid-catalyzed conversion of 1,8-cineole to cyclic hydrocarbon dimers were explored.In particular,the formation of the diene intermediates and the following dimerization of dienes was essential to synthesize tricyclic terpene dimers.The biphasic catalytic process accelerated the deoxygenation rate and enabled the dimerization with the aid of organic solvent while controlling the reaction rates to avoid the formation of solid residues.Moreover,this process also facilitated the product separation by organic solvent extraction while enabling easy recycle of the homogenous catalysts.展开更多
A series of Ag-ZrO_(2)/SiO_(2) catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and s...A series of Ag-ZrO_(2)/SiO_(2) catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity.According to the results of detailed characterizations(e.g.CO/pyridine-DRIFTS,XPS,TEM,NH3-TPD,and ^(1)H MAS NMR),it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO_(2) improved the interaction between Ag and ZrO_(2)/SiO_(2),creating more Ag^(δ+)active sites.The high dispersion of ZrO_(2) on SiO_(2) generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity,promoting the condensation of acetaldehyde to crotonaldehyde.These Zr-O-Si interfaces in close interaction with Ag^(δ+)species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol.The synergies among the interfaces resulted in retarded ethanol dehydration reactivity,balanced ethanol dehydrogenation and condensation reactions,and a subsequent high 1,3-butadiene yield.展开更多
Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 （SIO2/A1203 = 30） catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethan...Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 （SIO2/A1203 = 30） catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and l-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions （classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds） varied with time on stream （TOS）. At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5.展开更多
Biofuels and bio-based chemicals are getting more and more attention because of their sustainable and renewable properties and wide industrial applications.However,the low concentrations of the targeted products in th...Biofuels and bio-based chemicals are getting more and more attention because of their sustainable and renewable properties and wide industrial applications.However,the low concentrations of the targeted products in their fermentation broths,the complicated components of the broths and the high energy-intensive separation and purification process hinder the competitiveness of biofuels and biochemicals with the petro-based ones.Hence,the production and the separation of biofuels and bio-based chemicals in energy-saving,low-cost and greenness ways become hot topics nowadays.This review introduces the separation technologies(salting-out extraction,salting-out,sugaring-out extraction,and sugaring-out)that extract biobutanol,1,3-propanediol,2,3-butanediol,acetoin,organic acids and other bio-based chemicals from fermentation broths/aqueous solutions.Salting-out/sugar-ing-out extraction and salting-out/sugaring-out technologies display the high separating efficiency and the high targeted product yields.In addition,they are easy to operate and require low cost for separating products.Hence,they are the effective and potential technologies for separating targeted products in the wide industrial applications.The successful research into the salting-out/sugaring-out and salting-out/sugaring-out extraction not only affords biofuels and biochemical but also opens a door for the development of novel separation methods.展开更多
The production of higher terminal alcohols through CO hydrogenation according to the Fischer–Tropsch(F–T) process has been a topic of interest since the Institut Fran?ais du Pétrole(IFP) demonstrated shortchain...The production of higher terminal alcohols through CO hydrogenation according to the Fischer–Tropsch(F–T) process has been a topic of interest since the Institut Fran?ais du Pétrole(IFP) demonstrated shortchain C_1–C_6mixed alcohols production over cobalt–copper based catalysts. A number of catalyst formulations were screened for their suitability at that time. In particular, the addition of Cr, Zn, Al, Mn and V to Co Cu was investigated. In a number of patents, it was shown that catalyst preparation is crucial in these catalyst formulations and that high alcohols selectivity can only be achieved by carefully respecting the procedures and recipes. This short critical review highlights recent developments in Co Cu-based catalysts for higher terminal alcohols synthesis via F–T synthesis. Special attention will be given to catalyst preparation which according to developments in our group is based on oxalate precipitation. This way we show that the close association of Co and Cu on the one hand and promoter/dispersant on the other are of utmost importance to ensure high performance of the catalysts. We shall concentrate on 'Co Cu Mn','Co Cu Mo' and 'Co Cu Nb' catalyst formulations, all prepared via oxalate precipitation and combined with'entrainment techniques' if necessary, and show high total alcohols selectivity can be obtained with tunable Anderson-Schulz-Flory chain-lengthening probability. Either long-chain C_8–C_(14)terminal alcohols as feedstock for plasticizers, lubricants and detergents, or short-chain C_2–C_5alcohols as 'alkanol' fuels or fuel additives can be formed this way.展开更多
As one of the naturally abundant elements,carbon can present in different molecular structures(allotropes)and thus lead to various physi-cal/chemical properties of carbon-based materials which have found wide applicat...As one of the naturally abundant elements,carbon can present in different molecular structures(allotropes)and thus lead to various physi-cal/chemical properties of carbon-based materials which have found wide applications in a variety of fields including electrochemistry,optical,adsorption and catalysis,etc.On the other hand,its different allotropes also endow carbon-based materials with various morphostructures,which have been recently explored to prepare oxides and zeolites/zeotypes with tailored structures.In this review,we mainly summarize the recent advances in using carbon materials as hard templates to synthesize structural materials.Specifically,we focus on the development in the synthetic strategies,such as endotemplating,exotemplating approaches and using carbon materials as chemical reagents for the synthesis of metal carbides or nitrides,with an emphasis laid on the control of morphostructure.Meanwhile,the applications of the obtained materials will be highlighted,especially,in the field of heterogeneous catalysis where enhanced performances have been achieved with the materials derived from carbon-templated methods.展开更多
Porous heterogeneous lyophobic systems(HLSs)find potential applications in energy restoring,dissipating,and absorbing.However,the development of controllable HLSs still lacks rational structure design of nanoporous ma...Porous heterogeneous lyophobic systems(HLSs)find potential applications in energy restoring,dissipating,and absorbing.However,the development of controllable HLSs still lacks rational structure design of nanoporous materials matching the molecular sizes of adopted liquids.Besides that,thoroughly understanding the underlying transportation mechanism in the confined nano channels is greatly challenging.In this work,a series of Co/Zn bimetallic zeolitic imidazolate frameworks(ZIFs)with tunable structures were synthesized via regulating the Co to Zn ratios and employed to investigate the intrusion–extrusion of liquid water in confined nanopores.Structural characterizations confirm the heterometallic coordination in the Co/Zn-doped frameworks.Water intrusion–extrusion experiments unlock the relationship between the intrusion pressure and the nanopore size and realize the evolution of the HLSs between molecular spring and shock-absorber.In addition,cycling tests indicate the reversible structure change of Co/Zn ZIFs encountering pressure-induced water intrusion.In combination with molecular dynamics simulations,we present that the water multimers intrude into nanopores of ZIFs in chain-like forms along with dissociation of hydrogen bonds(HBs).Water molecules in the pre-intrusion state exhibit reduced HBs in response to the increase of pressure and linear structure with 1.6–3.0 HBs on average.After transition to the post-intrusion situation,the associative configuration of water tends to exhibit the tetrahedral structure.Herein,we highlight the roles of pore size and HB in synergically dominating the pressure-induced intrusion–extrusion of liquid water in hydrophobic nanopores.Furthermore,the present work can also guide the development of functional vip–host systems based on porous architectures.展开更多
A Ni/MgO catalyst was prepared via novel dielectric-barrier discharge （DBD） plasma decomposition method. The combined characterization of Bmnauer- Emmett-Teller measurement, X-ray diffraction, hydrogen temperature-p...A Ni/MgO catalyst was prepared via novel dielectric-barrier discharge （DBD） plasma decomposition method. The combined characterization of Bmnauer- Emmett-Teller measurement, X-ray diffraction, hydrogen temperature-programmed reduction and transmission electron microscopy shows that DBD plasma treatment enhances the support-metal interaction of Ni/MgO catalyst and facilitates the formation of smaller Ni particles. Sphere-like Ni particles form on plasma treated Ni/MgO catalysts. The plasma treated Ni/MgO catalyst shows a significantly improved low temperature activity and good stability for CO2 reforming of methane to syngas.展开更多
Catalytic fast pyrolysis （CFP） is deemed as the most promising way to convert biomass to transportation fuels or value added chemicals. Most works in literature so far have focused on the in situ CFP where the catal...Catalytic fast pyrolysis （CFP） is deemed as the most promising way to convert biomass to transportation fuels or value added chemicals. Most works in literature so far have focused on the in situ CFP where the catalysts are packed or co-fed with the feedstock in the pyrolysis reactor. However, the ex situ CFP with catalysts separated from the pyrolyzer has attracted more and more attentions due to its unique advantages of individually optimizing the pyrolysis conditions and catalyst performances. This review compares the differences between the in situ and ex situ CFP operation, and summarizes the development and progress of ex situ CFP applications, including the rationale and performances of different catalysts, and the choices of suitable ex situ reactor systems. Due to the complex composition of bio-oil, no single approach was believed to be able to solve the problems completely among all those existing technologies. With the increased understanding of catalyst performances and reaction process, the recent trend toward an integration of biomass or bio-oil fractionation with subsequent thermo/biochemical conversion routes is also discussed.展开更多
The performance of CoCrMo alloy in orthopaedic implants may be unfavourably affected by hyaluronic acid(HA)in synovial fluid.In this study,the authors aimed to understand the interactions between HA and CoCrMo using d...The performance of CoCrMo alloy in orthopaedic implants may be unfavourably affected by hyaluronic acid(HA)in synovial fluid.In this study,the authors aimed to understand the interactions between HA and CoCrMo using dedicated electrochemical experiments and surface analyses.A sequence of electrochemical measurements(open-circuit potential,linear polarization resistance,potentiodynamic and potentiostatic polarizations)was run on LC-CoCrMo(ASTM F1537)in Dulbecco's phosphate-buffered saline(DPBS)solution with and without HA and in DPBS mixed with newborn calf serum(NCS)and HA,partially under simultaneous recording of surface pH using custom-made microelectrodes.Samples were analysed by optical and elec-tron microscopy.HA had no significant impact on the corrosion potential of CoCrMo alloy(ECORR=−173�8,−211�16,and−254�30 V_(Ag/AgCl),in DPBS,DPBS+HA,and DPBS+NCS+HA,respectively).Average current density values at the transpassive domain were double in DPBS compared to DPBS+HA and DPBS+NCS+HA.At potentials above+0.6 V_(Ag/AgCl),surface pH values decreased from 7.5 to 6.5 in DPBS and from 7.5 to below 4 in DPBS+HA.In conclusion,the presence of HA did not compromise the corrosion resistance of CoCrMo alloy at free potential,but it enhanced acidic conditions at the near surface under anodic-applied potential in the transpassive domain.展开更多
基金financially supported by the Training Program of the Major Research Plan of the National Natural Science Foundation of China(grant no.91634112)the Natural Science Foundation of Shanghai(grant no.16ZR1408100)+2 种基金the Fundamental Research Funds for the Central Universities of China(grant no.22A201514010)the Open Project of State Key Laboratory of Chemical Engineering(SKL-Ch E-16C01)the institutional funds from the Gene and Linda Voiland School of Chemical Engineering and Bioengineering at Washington State University
文摘The rheological properties of South China Sea （SCS） crude oil were studied. A group of synthetic long-chain polymers, including octadecyl acrylate-maleic anhydride bidodecyl amide copolymer （VR-D）, octadecyl acrylate-maleic anhydride bioctadecyl amide copolymer （VR-O） and octadecyl acrylate-maleic anhydride phenly amide copolymer （VR-A）, were employed to serve as viscosity reducers （VRs）. Their performance was evaluated by both experimental and computational methodologies. The results suggest that the SCS crude oil has low wax content yet high resin and asphaltene contents, which lead to high viscosity through formation of association structures. Additionally, the SCS crude oil appears to be a pseudoplastic fluid showing linear shear stress-shear rate dependence at low temperature. Interestingly, it gradually evolves into a Newtonian fluid with exponential relationship between shear stress and shear rate at higher temperature. Synthetic VRs demonstrate desirable and effective performance on improvement of the rheological properties of SCS crude oil. Upon the introduction of 1000ppm VR-O, which is synthesized by using octadecylamine in the aminolysis reaction, the viscosity of SCS crude oil is decreased by 44.2% at 15 ℃ and 40.2% at 40℃. The computational study suggests significant energy level increase and shear stress decrease for VR-containing crude oil systems.
基金supported by the Major Research Plan of National Natural Science Foundation of China(No.91545114 and No.91545203)the National Natural Science Foundation of China(No.21576227)。
文摘Supported Pd catalysts with varied Pd loadings(x=0.5 wt%, 2.0 wt%, 5.0 wt%, 7.5 wt%, 15.0 wt%) were prepared by the incipient wetness impregnation method using a ZnAl_(2)O_(4) spinel support.We found that ZnAl_(2)O_(4) supported Pd catalysts with low Pd loadings(e.g., 0.5 wt%) are very selective in syngas conversion to methanol and dimethyl-ether(DME).XRD and TEM characterization shows that,after reduction at350℃,PdZnβ phase with Pd:Zn molar ratio of 1:1 is favored to form predominantly on the spinel support at relatively low Pd loadings,i.e.less than 5.0 wt%, while Pd-rich PdZnα alloy phase exists at Pd loadings above 5.0 wt%.A higher reduction temperature such as 500℃ can facilitate the transformation from PdZnα to PdZnβ phase in those catalysts with high Pd loading.We further found that catalysts with predominant PdZnβ phase are selective in the methanol and DME production from syngas,while the presence of PdZnα phase leads to the notable formation of alkanes byproducts,resulting in reduced methanol and DME selectivity.DME formation from dehydration of methanol depends on the acidity of catalysts,which was found to increase with Pd loading,probably due to the formation of isolated Al_(2)O_(3) as a result of Zn migrating from ZnAl_(2)O_(4) spinel phase to form the PdZn phases with Pd.
基金supported by the National Natural Science Foundation of China(91545114,91545203,and 21576227)the 985 Program of the Chemistry and Chemical Engineering disciplines of Xiamen University~~
文摘Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical, through oxidative esterification over Au-based catalysts. Detailed experimental studies showed that Au on amphoteric supports with appropriate strength and balanced ratio of acid and base sites can facilitate the desired oxidative-esterification pathway without accelerating undesired aldol-condensation or Cannizzaro reactions. In particular, hydroxyapatite (with a Ca/P ratio of 1.62) supported Au achieved 87% selectivity to methyl pyruvate at an acetol conversion of 62%.
基金funding for this work was provided by Ocean Ethanol LLC
文摘This paper reports an experimental study on catalytic conversion of carbon dioxide to methanol, ethanol and acetic acid. Satalysts having different catalytic functions were synthesized and combined in different ways to enhance the selectivity to desired products. The combined catalyst system possessed the following functions： methanol synthesis, Fischer-Tropsch synthesis, water-gas-shift and hydrogenation. Results showed that the methods of integrating these catalytic functions played an important role in achieving the desired product selectivity. We speculate that if methanol synthesis sites were located adjacent to the C--C chain growth sites, the formation rate of C2 oxygenates would be enhanced. The advantage of using a high temperature methanol catalyst PdZnA1 in the combined catalyst system was demonstrated. In the presence of PdZnA1 catalyst, the combined catalyst system was stable at 380 ~C. It was observed that, at high temperature, kinetics favored oxygenate formation. The results implied that the process can be intensified by operating at high temperature using Pd-based methanol synthesis catalyst. Steam reforming of the byproduct organics was demonstrated as a means to provide supplemental hydrogen. Preliminary process design, simulation, and economic analysis of the proposed CO2 conversion process were carded out. Economic analysis indicates how ethanol production cost was affected by the price of CO2 and hydrogen.
文摘Terpenoids have drawn much attention to scientists in synthesizing high-performance bio-jet fuels due to their ring structures,which feature potential high densities.Here,a facile biphasic catalytic process has been developed for the production of high-density tricyclic hydrocarbon biofuels from a monoterpenoid,1,8-cineole,using sulfuric acid(H2SO4)as the homogeneous catalyst.A^100%conversion of 1,8-cineole and a>40%carbon yield of cyclic dimers were achieved at 100℃within two hours.The mechanism for the acid-catalyzed conversion of 1,8-cineole to cyclic hydrocarbon dimers were explored.In particular,the formation of the diene intermediates and the following dimerization of dienes was essential to synthesize tricyclic terpene dimers.The biphasic catalytic process accelerated the deoxygenation rate and enabled the dimerization with the aid of organic solvent while controlling the reaction rates to avoid the formation of solid residues.Moreover,this process also facilitated the product separation by organic solvent extraction while enabling easy recycle of the homogenous catalysts.
基金supported by the U.S.Department of Energy(DOE),Office of Basic Energy Sciences,Division of Chemical Sciences,Biosciences,and Geosciences Catalysis Program(DE-AC05-RL01830,FWP-47319)National Natural Science Foundation of China(21776268)Shandong Chambroad Holding Company。
文摘A series of Ag-ZrO_(2)/SiO_(2) catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity.According to the results of detailed characterizations(e.g.CO/pyridine-DRIFTS,XPS,TEM,NH3-TPD,and ^(1)H MAS NMR),it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO_(2) improved the interaction between Ag and ZrO_(2)/SiO_(2),creating more Ag^(δ+)active sites.The high dispersion of ZrO_(2) on SiO_(2) generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity,promoting the condensation of acetaldehyde to crotonaldehyde.These Zr-O-Si interfaces in close interaction with Ag^(δ+)species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol.The synergies among the interfaces resulted in retarded ethanol dehydration reactivity,balanced ethanol dehydrogenation and condensation reactions,and a subsequent high 1,3-butadiene yield.
基金the Pacific Northwest National Laboratory's Laboratory Directed Research and Development Funding
文摘Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 （SIO2/A1203 = 30） catalyst was studied at 360 C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and l-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions （classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds） varied with time on stream （TOS）. At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5.
文摘Biofuels and bio-based chemicals are getting more and more attention because of their sustainable and renewable properties and wide industrial applications.However,the low concentrations of the targeted products in their fermentation broths,the complicated components of the broths and the high energy-intensive separation and purification process hinder the competitiveness of biofuels and biochemicals with the petro-based ones.Hence,the production and the separation of biofuels and bio-based chemicals in energy-saving,low-cost and greenness ways become hot topics nowadays.This review introduces the separation technologies(salting-out extraction,salting-out,sugaring-out extraction,and sugaring-out)that extract biobutanol,1,3-propanediol,2,3-butanediol,acetoin,organic acids and other bio-based chemicals from fermentation broths/aqueous solutions.Salting-out/sugar-ing-out extraction and salting-out/sugaring-out technologies display the high separating efficiency and the high targeted product yields.In addition,they are easy to operate and require low cost for separating products.Hence,they are the effective and potential technologies for separating targeted products in the wide industrial applications.The successful research into the salting-out/sugaring-out and salting-out/sugaring-out extraction not only affords biofuels and biochemical but also opens a door for the development of novel separation methods.
基金supported by the National Science Foundation under contract No.CBET-1438227
文摘The production of higher terminal alcohols through CO hydrogenation according to the Fischer–Tropsch(F–T) process has been a topic of interest since the Institut Fran?ais du Pétrole(IFP) demonstrated shortchain C_1–C_6mixed alcohols production over cobalt–copper based catalysts. A number of catalyst formulations were screened for their suitability at that time. In particular, the addition of Cr, Zn, Al, Mn and V to Co Cu was investigated. In a number of patents, it was shown that catalyst preparation is crucial in these catalyst formulations and that high alcohols selectivity can only be achieved by carefully respecting the procedures and recipes. This short critical review highlights recent developments in Co Cu-based catalysts for higher terminal alcohols synthesis via F–T synthesis. Special attention will be given to catalyst preparation which according to developments in our group is based on oxalate precipitation. This way we show that the close association of Co and Cu on the one hand and promoter/dispersant on the other are of utmost importance to ensure high performance of the catalysts. We shall concentrate on 'Co Cu Mn','Co Cu Mo' and 'Co Cu Nb' catalyst formulations, all prepared via oxalate precipitation and combined with'entrainment techniques' if necessary, and show high total alcohols selectivity can be obtained with tunable Anderson-Schulz-Flory chain-lengthening probability. Either long-chain C_8–C_(14)terminal alcohols as feedstock for plasticizers, lubricants and detergents, or short-chain C_2–C_5alcohols as 'alkanol' fuels or fuel additives can be formed this way.
基金supported by the National Natural Science Foundation of China(21006024)Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials,Department of Chemistry,Fudan University(No.2010MCIMKF)+2 种基金Fundamental Research Funds for the Central Universities(WA0914023)CPNP Foundation(2011D-5006-0507)sponsored by the Shanghai Pujiang Program(11PJ1402600)for talented returnees
文摘As one of the naturally abundant elements,carbon can present in different molecular structures(allotropes)and thus lead to various physi-cal/chemical properties of carbon-based materials which have found wide applications in a variety of fields including electrochemistry,optical,adsorption and catalysis,etc.On the other hand,its different allotropes also endow carbon-based materials with various morphostructures,which have been recently explored to prepare oxides and zeolites/zeotypes with tailored structures.In this review,we mainly summarize the recent advances in using carbon materials as hard templates to synthesize structural materials.Specifically,we focus on the development in the synthetic strategies,such as endotemplating,exotemplating approaches and using carbon materials as chemical reagents for the synthesis of metal carbides or nitrides,with an emphasis laid on the control of morphostructure.Meanwhile,the applications of the obtained materials will be highlighted,especially,in the field of heterogeneous catalysis where enhanced performances have been achieved with the materials derived from carbon-templated methods.
基金supported by the National Natural Science Foundation of China(Nos.22178109 and 21878097)the Natural Science Foundation of Shanghai(No.21ZR1417700)。
文摘Porous heterogeneous lyophobic systems(HLSs)find potential applications in energy restoring,dissipating,and absorbing.However,the development of controllable HLSs still lacks rational structure design of nanoporous materials matching the molecular sizes of adopted liquids.Besides that,thoroughly understanding the underlying transportation mechanism in the confined nano channels is greatly challenging.In this work,a series of Co/Zn bimetallic zeolitic imidazolate frameworks(ZIFs)with tunable structures were synthesized via regulating the Co to Zn ratios and employed to investigate the intrusion–extrusion of liquid water in confined nanopores.Structural characterizations confirm the heterometallic coordination in the Co/Zn-doped frameworks.Water intrusion–extrusion experiments unlock the relationship between the intrusion pressure and the nanopore size and realize the evolution of the HLSs between molecular spring and shock-absorber.In addition,cycling tests indicate the reversible structure change of Co/Zn ZIFs encountering pressure-induced water intrusion.In combination with molecular dynamics simulations,we present that the water multimers intrude into nanopores of ZIFs in chain-like forms along with dissociation of hydrogen bonds(HBs).Water molecules in the pre-intrusion state exhibit reduced HBs in response to the increase of pressure and linear structure with 1.6–3.0 HBs on average.After transition to the post-intrusion situation,the associative configuration of water tends to exhibit the tetrahedral structure.Herein,we highlight the roles of pore size and HB in synergically dominating the pressure-induced intrusion–extrusion of liquid water in hydrophobic nanopores.Furthermore,the present work can also guide the development of functional vip–host systems based on porous architectures.
文摘A Ni/MgO catalyst was prepared via novel dielectric-barrier discharge （DBD） plasma decomposition method. The combined characterization of Bmnauer- Emmett-Teller measurement, X-ray diffraction, hydrogen temperature-programmed reduction and transmission electron microscopy shows that DBD plasma treatment enhances the support-metal interaction of Ni/MgO catalyst and facilitates the formation of smaller Ni particles. Sphere-like Ni particles form on plasma treated Ni/MgO catalysts. The plasma treated Ni/MgO catalyst shows a significantly improved low temperature activity and good stability for CO2 reforming of methane to syngas.
文摘Catalytic fast pyrolysis （CFP） is deemed as the most promising way to convert biomass to transportation fuels or value added chemicals. Most works in literature so far have focused on the in situ CFP where the catalysts are packed or co-fed with the feedstock in the pyrolysis reactor. However, the ex situ CFP with catalysts separated from the pyrolyzer has attracted more and more attentions due to its unique advantages of individually optimizing the pyrolysis conditions and catalyst performances. This review compares the differences between the in situ and ex situ CFP operation, and summarizes the development and progress of ex situ CFP applications, including the rationale and performances of different catalysts, and the choices of suitable ex situ reactor systems. Due to the complex composition of bio-oil, no single approach was believed to be able to solve the problems completely among all those existing technologies. With the increased understanding of catalyst performances and reaction process, the recent trend toward an integration of biomass or bio-oil fractionation with subsequent thermo/biochemical conversion routes is also discussed.
基金Division of Chemical,Bioengineering,Environmental,and Transport Systems,Grant/Award Number:1706889。
文摘The performance of CoCrMo alloy in orthopaedic implants may be unfavourably affected by hyaluronic acid(HA)in synovial fluid.In this study,the authors aimed to understand the interactions between HA and CoCrMo using dedicated electrochemical experiments and surface analyses.A sequence of electrochemical measurements(open-circuit potential,linear polarization resistance,potentiodynamic and potentiostatic polarizations)was run on LC-CoCrMo(ASTM F1537)in Dulbecco's phosphate-buffered saline(DPBS)solution with and without HA and in DPBS mixed with newborn calf serum(NCS)and HA,partially under simultaneous recording of surface pH using custom-made microelectrodes.Samples were analysed by optical and elec-tron microscopy.HA had no significant impact on the corrosion potential of CoCrMo alloy(ECORR=−173�8,−211�16,and−254�30 V_(Ag/AgCl),in DPBS,DPBS+HA,and DPBS+NCS+HA,respectively).Average current density values at the transpassive domain were double in DPBS compared to DPBS+HA and DPBS+NCS+HA.At potentials above+0.6 V_(Ag/AgCl),surface pH values decreased from 7.5 to 6.5 in DPBS and from 7.5 to below 4 in DPBS+HA.In conclusion,the presence of HA did not compromise the corrosion resistance of CoCrMo alloy at free potential,but it enhanced acidic conditions at the near surface under anodic-applied potential in the transpassive domain.
