The low porosity of metal-organic framework glass makes it difficult to prepare membranes with high permeability.To solve this problem,we fabricated a series of self-supported zeolite glass composite membranes with di...The low porosity of metal-organic framework glass makes it difficult to prepare membranes with high permeability.To solve this problem,we fabricated a series of self-supported zeolite glass composite membranes with different 4A zeolite loadings using the abundant pore structure of the zeolite.The 4A zeolite embedded in the zeolite glass composite membrane preserved the ligand bonds and chemical structure.The self-supported zeolite glass composite membranes exhibited good interfacial compatibility.More importantly,the incorporation of the 4A zeolite significantly improved the CO_(2)adsorption capacity of the pure a_(g)ZIF-62 membranes.In addition,gas separation performance measurements showed that the(a_(g)ZIF-62)_(0.7)(4A)_(0.3)membrane had a permeability of 13,329 Barrer for pure CO_(2)and an ideal selectivity of 31.7 for CO_(2)/CH_(4),which exceeded Robeson's upper bound.The(a_(g)ZIF-62)_(0.7)(4A)_(0.3)membrane exhibited good operational stability in the variable pressure test and 48 h long-term continuous test.This study provides a method for preparing zeolite glass composite membranes.展开更多
This paper reports on a new microporous composite silica membrane prepared via acid-catalyzed polymeric route of sol-gel method with tetraethylorthosilicate(TEOS)and a bridged silsesquioxane[1,2-bis(triethoxysilyl)eth...This paper reports on a new microporous composite silica membrane prepared via acid-catalyzed polymeric route of sol-gel method with tetraethylorthosilicate(TEOS)and a bridged silsesquioxane[1,2-bis(triethoxysilyl)ethane, BTESE]as precursors.A stable nano-sized composite silica sol with a mean volume size of^5 nm was synthesized. A 150 nm-thick defect-free composite silica membrane was deposited on disk support consisting of macroporous α-Al2O3 and mesoporousγ-Al2O3 intermediate layer by using dip-coating approach,followed by calcination under pure nitrogen atmosphere.The composite silica membranes exhibit molecular sieve properties for small gases like H2,CO2,O2,N2,CH4 and SF6 with hydrogen permeances in the range of(1-4)×10 -7mol·m -2·s -1·Pa -1(measured at 200°C,3.0×105 Pa).With respect to the membrane calcined at 500°C,it is found that the permselectivities of H 2 (0.289 nm)with respect to N2(0.365 nm),CH4(0.384 nm)and SF6(0.55 nm)are 22.9,42 and>1000,respectively, which are all much higher than the corresponding Knudsen values(H2/N2=3.7,H2/CH4=2.8,and H2/SF6=8.5).展开更多
In this work, the effects of support surface pore structures(including surface pore size, surface pore density and surface porosity) on the performance of thin film composite(TFC) gas separation membrane over a wide p...In this work, the effects of support surface pore structures(including surface pore size, surface pore density and surface porosity) on the performance of thin film composite(TFC) gas separation membrane over a wide pressure range(from 0.3 to 2.0 MPa) were studied. To fulfill it, the polysulfone(PSf) supports with different surface pore structures were prepared. Two kinds of wide-accepted polymeric membrane materials, i.e., polyvinylamine(PVAm) and Pebax 1657 copolymer, were used as skin layer materials. We pointed out for the first time that the support surface average pore size and pore density could affect the chain mobility of polymer of skin layer at the support surface pore entrance, then, can affect the TFC membrane performance. Besides, we also discussed the effects of support on the TFC membrane performance when the feed pressure changes for the first time. This work can provide guidance for choosing a suitable support for TFC gas separation membrane.展开更多
Industrial thin-film composite(TFC)membranes achieve superior gas separation properties from high-performance selective layer materials,while the success of membrane technology relies on high-performance gutter layers...Industrial thin-film composite(TFC)membranes achieve superior gas separation properties from high-performance selective layer materials,while the success of membrane technology relies on high-performance gutter layers to achieve production scalability and low-cost manufacturing.However,the current literature predominantly focuses on the design of polymer architectures to obtain high permeability and selectivity,while the art of fabricating gutter layers is usually safeguarded by industrial manufacturers and appears lackluster to academic researchers.This is the first report aiming to provide a comprehensive and critical review of state-of-the-art gutter layer materials and their design and modification to enable TFC membranes with superior separation performance.We first elucidate the importance of the gutter layer on membrane performance through modeling and experimental results.Then various gutter layer materials used to obtain high-performance composite membranes are critically reviewed,and the strategies to improve their compatibility with the selective layer are highlighted,such as oxygen plasma treatment,polydopamine deposition,and surface grafting.Finally,we present the opportunities of the gutter layer design for practical applications.展开更多
The development of defect-free composite membrane(CM) is often challenging due to poor dispersion and distribution of filler particles in the polymer matrix. Despite the attractive physicochemical properties and gas s...The development of defect-free composite membrane(CM) is often challenging due to poor dispersion and distribution of filler particles in the polymer matrix. Despite the attractive physicochemical properties and gas separation performance of carbon nanotube(CNT) based CM, CNT displayed poor dispersion characteristics in most polymer matrix domain. Instead of incorporating CNT, a viable alternative, carbon nanofiber(CNF) which exhibits similar properties as CNT, but improved dispersion quality in the polymer matrix is found. In this work,CNF particles were incorporated in poly(2,6-dimethyl-1,4-phenylene oxide)(PPOdm) polymer continuous phase for CM development. The optimum gas separation performance of the PPOdm-CNF CM(11.25 at 197.02 barrer of CO_2 permeability) was obtained at 3 wt% of CNF loading. Compared to pristine PPOdmmembrane,CO_2 permeability and CO_2/CH_4 selectivity of PPOdm-3 wt% CNF CM were enhanced by 180% and 55%, respectively.At 3 wt% CNF loading, the filler particles were dispersed and distributed more homogenously, in which no obvious CNF agglomeration was observed. In addition, the incorporation of CNF particles also enhanced the mechanical and thermal properties of the resultant CM.展开更多
Microporous polyvinylidene fluoride(PVDF)hollow fibre membranes were spun using the dry-wet phaseinversion method.By means of dip-coating technique,a uniform coating with thickness of around 5-12 μm of polyvinyldimet...Microporous polyvinylidene fluoride(PVDF)hollow fibre membranes were spun using the dry-wet phaseinversion method.By means of dip-coating technique,a uniform coating with thickness of around 5-12 μm of polyvinyldimethylsiloxane(PVDMS)was formed on the surface of porous PVDF hollow fibers.The structural parameters of PVDFsubstrate membrane were estimated by gas permeation test.Using N_2/O_2 as the medium,the separation properties ofPVDMS-PVDF composite hollow fiber membranes were also evaluated experimentally.The experimental data of bothpermeability and selectivity are in good agreement with the theoretical results predicted by the presented pore-distributionmodel.In order to obtain the compact composite membrane free of defects by the dip-coating technique,the thickness ofPVDMS skin must be higher than 5 μm.展开更多
Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustio...Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.展开更多
Palladium membranes were prepared on an α-alumina support bymetal-organic compound chemical vapor deposition (MOCVD) method frompalladium (II) acetate precursor. Permeation properties of hydrogenand helium gas were s...Palladium membranes were prepared on an α-alumina support bymetal-organic compound chemical vapor deposition (MOCVD) method frompalladium (II) acetate precursor. Permeation properties of hydrogenand helium gas were studied as a function of the number of times ofdeposition of palladium on the peeling off phenomenon of palladium,which is common in electroless plated membrane, was observed. Silicawas introduced into the pores to prevent the palladium grain frompeeling off. The palladium-silica conjugated membrane does not showthe peeling off phenomenon and can withstand the high temperature upto 800 deg. C which is the upper limit of our apparatus.展开更多
The composite membranes with cellulose acetate（CA） as the separating layer material and polyacrylonitrile（PAN） as the supporting layer material were prepared for separating caprolactam（CPL） from CPL/water mixtur...The composite membranes with cellulose acetate（CA） as the separating layer material and polyacrylonitrile（PAN） as the supporting layer material were prepared for separating caprolactam（CPL） from CPL/water mixtures by pervaporation technique.The swelling experiments were carried out to investigate the effects of swelling time and CPL concentration on the degree of swelling.The results showed that the CA membrane reached swelling equilibrium within 24 h,and the degree of swelling first slightly decreased then increased with the increase of CPL concentration in the feed under the experimental conditions.Respectively comparing flux with permeance,and separation factor with selectivity,we found out that the separation performance of the CA/PAN composite membrane is more strongly dependent on its hydrophilic/hydrophobic nature as well as on the effects of operating parameters,such as feed composition concentration and feed temperature.展开更多
基金supported by the S&T Program of Hebei(no.22373709D).
文摘The low porosity of metal-organic framework glass makes it difficult to prepare membranes with high permeability.To solve this problem,we fabricated a series of self-supported zeolite glass composite membranes with different 4A zeolite loadings using the abundant pore structure of the zeolite.The 4A zeolite embedded in the zeolite glass composite membrane preserved the ligand bonds and chemical structure.The self-supported zeolite glass composite membranes exhibited good interfacial compatibility.More importantly,the incorporation of the 4A zeolite significantly improved the CO_(2)adsorption capacity of the pure a_(g)ZIF-62 membranes.In addition,gas separation performance measurements showed that the(a_(g)ZIF-62)_(0.7)(4A)_(0.3)membrane had a permeability of 13,329 Barrer for pure CO_(2)and an ideal selectivity of 31.7 for CO_(2)/CH_(4),which exceeded Robeson's upper bound.The(a_(g)ZIF-62)_(0.7)(4A)_(0.3)membrane exhibited good operational stability in the variable pressure test and 48 h long-term continuous test.This study provides a method for preparing zeolite glass composite membranes.
基金Supported by the National Natural Science Foundation of China(20906047)the State Key Laboratory of Chemical Engineering(SKL-ChE-09A01)the State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201002)
文摘This paper reports on a new microporous composite silica membrane prepared via acid-catalyzed polymeric route of sol-gel method with tetraethylorthosilicate(TEOS)and a bridged silsesquioxane[1,2-bis(triethoxysilyl)ethane, BTESE]as precursors.A stable nano-sized composite silica sol with a mean volume size of^5 nm was synthesized. A 150 nm-thick defect-free composite silica membrane was deposited on disk support consisting of macroporous α-Al2O3 and mesoporousγ-Al2O3 intermediate layer by using dip-coating approach,followed by calcination under pure nitrogen atmosphere.The composite silica membranes exhibit molecular sieve properties for small gases like H2,CO2,O2,N2,CH4 and SF6 with hydrogen permeances in the range of(1-4)×10 -7mol·m -2·s -1·Pa -1(measured at 200°C,3.0×105 Pa).With respect to the membrane calcined at 500°C,it is found that the permselectivities of H 2 (0.289 nm)with respect to N2(0.365 nm),CH4(0.384 nm)and SF6(0.55 nm)are 22.9,42 and>1000,respectively, which are all much higher than the corresponding Knudsen values(H2/N2=3.7,H2/CH4=2.8,and H2/SF6=8.5).
基金Supported by the National Natural Science Foundation of China(21436009)the National High-tech Research and Development Program(2012AA03A611)the Program of Introducing Talents of Discipline to Universities(B06006)
文摘In this work, the effects of support surface pore structures(including surface pore size, surface pore density and surface porosity) on the performance of thin film composite(TFC) gas separation membrane over a wide pressure range(from 0.3 to 2.0 MPa) were studied. To fulfill it, the polysulfone(PSf) supports with different surface pore structures were prepared. Two kinds of wide-accepted polymeric membrane materials, i.e., polyvinylamine(PVAm) and Pebax 1657 copolymer, were used as skin layer materials. We pointed out for the first time that the support surface average pore size and pore density could affect the chain mobility of polymer of skin layer at the support surface pore entrance, then, can affect the TFC membrane performance. Besides, we also discussed the effects of support on the TFC membrane performance when the feed pressure changes for the first time. This work can provide guidance for choosing a suitable support for TFC gas separation membrane.
基金support from the U.S.Department of Energy National Energy Technology Laboratory(DE-FE0031736)the New York State Foundation for Science,Technology and Innovation(NYSTAR).
文摘Industrial thin-film composite(TFC)membranes achieve superior gas separation properties from high-performance selective layer materials,while the success of membrane technology relies on high-performance gutter layers to achieve production scalability and low-cost manufacturing.However,the current literature predominantly focuses on the design of polymer architectures to obtain high permeability and selectivity,while the art of fabricating gutter layers is usually safeguarded by industrial manufacturers and appears lackluster to academic researchers.This is the first report aiming to provide a comprehensive and critical review of state-of-the-art gutter layer materials and their design and modification to enable TFC membranes with superior separation performance.We first elucidate the importance of the gutter layer on membrane performance through modeling and experimental results.Then various gutter layer materials used to obtain high-performance composite membranes are critically reviewed,and the strategies to improve their compatibility with the selective layer are highlighted,such as oxygen plasma treatment,polydopamine deposition,and surface grafting.Finally,we present the opportunities of the gutter layer design for practical applications.
基金Yayasan Universiti Teknologi PETRONAS (YUTP-FRG grant 0153AA-E08)CO_2 Research Centre (CO_2RES) for supporting this work
文摘The development of defect-free composite membrane(CM) is often challenging due to poor dispersion and distribution of filler particles in the polymer matrix. Despite the attractive physicochemical properties and gas separation performance of carbon nanotube(CNT) based CM, CNT displayed poor dispersion characteristics in most polymer matrix domain. Instead of incorporating CNT, a viable alternative, carbon nanofiber(CNF) which exhibits similar properties as CNT, but improved dispersion quality in the polymer matrix is found. In this work,CNF particles were incorporated in poly(2,6-dimethyl-1,4-phenylene oxide)(PPOdm) polymer continuous phase for CM development. The optimum gas separation performance of the PPOdm-CNF CM(11.25 at 197.02 barrer of CO_2 permeability) was obtained at 3 wt% of CNF loading. Compared to pristine PPOdmmembrane,CO_2 permeability and CO_2/CH_4 selectivity of PPOdm-3 wt% CNF CM were enhanced by 180% and 55%, respectively.At 3 wt% CNF loading, the filler particles were dispersed and distributed more homogenously, in which no obvious CNF agglomeration was observed. In addition, the incorporation of CNF particles also enhanced the mechanical and thermal properties of the resultant CM.
基金This work was supported by the National Natural Science Foundation of China(No.20076025).
文摘Microporous polyvinylidene fluoride(PVDF)hollow fibre membranes were spun using the dry-wet phaseinversion method.By means of dip-coating technique,a uniform coating with thickness of around 5-12 μm of polyvinyldimethylsiloxane(PVDMS)was formed on the surface of porous PVDF hollow fibers.The structural parameters of PVDFsubstrate membrane were estimated by gas permeation test.Using N_2/O_2 as the medium,the separation properties ofPVDMS-PVDF composite hollow fiber membranes were also evaluated experimentally.The experimental data of bothpermeability and selectivity are in good agreement with the theoretical results predicted by the presented pore-distributionmodel.In order to obtain the compact composite membrane free of defects by the dip-coating technique,the thickness ofPVDMS skin must be higher than 5 μm.
基金funded by the Helmholtz Association of German Research Centersthe funding given by the German Federal Ministry for Economic Affairs and Energy to finance the research project METPORE Ⅱ (03ET2016)+2 种基金the METPORE Ⅱ project partnersSSC Strategic Science Consult GmbHBORSIG Membrane Technology GmbH
文摘Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.
文摘Palladium membranes were prepared on an α-alumina support bymetal-organic compound chemical vapor deposition (MOCVD) method frompalladium (II) acetate precursor. Permeation properties of hydrogenand helium gas were studied as a function of the number of times ofdeposition of palladium on the peeling off phenomenon of palladium,which is common in electroless plated membrane, was observed. Silicawas introduced into the pores to prevent the palladium grain frompeeling off. The palladium-silica conjugated membrane does not showthe peeling off phenomenon and can withstand the high temperature upto 800 deg. C which is the upper limit of our apparatus.
基金Supported by the Research Foundation of China Petroleum and Chemical Corporation (SINOPEC)
文摘The composite membranes with cellulose acetate（CA） as the separating layer material and polyacrylonitrile（PAN） as the supporting layer material were prepared for separating caprolactam（CPL） from CPL/water mixtures by pervaporation technique.The swelling experiments were carried out to investigate the effects of swelling time and CPL concentration on the degree of swelling.The results showed that the CA membrane reached swelling equilibrium within 24 h,and the degree of swelling first slightly decreased then increased with the increase of CPL concentration in the feed under the experimental conditions.Respectively comparing flux with permeance,and separation factor with selectivity,we found out that the separation performance of the CA/PAN composite membrane is more strongly dependent on its hydrophilic/hydrophobic nature as well as on the effects of operating parameters,such as feed composition concentration and feed temperature.
