Structures and Properties of Supported Polyimide/SnO2 Hybrid Membranes

A series of polyimide/SnO2 hybrid membranes supported on TiO2/kieselguhr-mullite were prepared from polyimide with a large amount of carboxyl and SnO2 sol via a sol-gel process. The SnO2 phase chemically linked with the polyimide through the pendant carboxyl along the polyimide. The hybrid membranes were highly homogeneous, and when the SnO2 contents reached 15wt% the SnO2 phase was observed as particles with a diameter of 5 nm dispersed in the hybrid membranes . The cross-linking between the SnO2 phase and polyimide effectively enhanced the glass temperature of the hybrid films. With the increasing of the SnO2 contents, the pore sizes of the membranes decreased, and their pore sizes were mainly focused on 3.8, 3.1, 2.8 and 2.4 nm. The hybrid membranes showed higher permeability for H2, CO2, CO and H2O when compared to the pure polyimide. The separation factors of the polyimide/SnO2 hybrid membranes with 15wt% SnO2 content for H2/N2, CO2/N2, CO/N2 and H2O/N2 were 54.1, 30.2, 35.9 and 40.1, respectively.     

Alumina-supported SAPO-34 membranes for CO2/CH4 separation

SAPO-34 membranes were prepared by in situ crystallization on alpha-Al2O3 porous supports. The crystal size of the seeds was effectively controlled in the 0.7 to 8.5 micron range by employing different structure-directing agents. Seeds smaller than 1 micron produced membranes with CO2/CH4 separation selectivities higher than 170 and unprecedented CO2 permeances as high as 2.0 x 10(-6) mol/m2.s.Pa at 295 K and a feed pressure of 224 kPa. The membranes effectively separated CO2/CH4 mixtures up to 1.7 MPa.     

Matrimid®5218/PSf双层非对称中空纤维膜的制备及其气体分离性能研究

以商业化聚酰亚胺Matrimid®5218作为功能层材料, 聚砜作为支撑层材料, 采用共挤出法制备双层非对称中空纤维气体分离膜. 所制备的双层非对称中空纤维膜具有致密无缺陷的超薄皮层, 致密皮层厚度约为0.21 μm. 在25 ℃, 0.5 MPa下, CO2/CH4的选择性系数达51.39, CO2的渗透系数为46.29 GPU, O2/N2的选择性系数达到7.13, O2的渗透速率为6.38 GPU. 考察了温度和压力对膜的渗透系数和选择性系数的影响, 并考察了物理老化对膜性能的影响.     

The Influence of Polymer Concentration and Formation Technique on Gas Transport and Gas Sorption Properties of Copolyetherimide-Based Composite Membranes Containing MIL-101 Filler

Composite mixed-matrix membranes for gas separation containing copolyetherimide Siltem® as the polymer matrix and metal-organic framework MIL-101 (10 wt %) as the active filler, were obtained using dry and wet-dry formation techniques. It has been found that the polymer concentration in the initial solution does not significantly affect the CO2 and CH4 permeability of the film membranes obtained by dry molding. The addition of MIL-101 increases the CO2/CH4 selectivity of the dry-formed membranes approximately by 2 times compared to the selectivity of the filler-free polymer membranes. The materials synthesized by the wet-dry formation possess increased permeability and inverted CO2/CH4 selectivity, which indicates a change in the gas transport mechanism. With the increase of polymer concentration, the selectivity of the membranes obtained by the wet-dry technique, increases significantly due to the formation of the dense selective layer.     

CO2选择性透过膜材料的制备

作为一种主要温室气体和一种重要的"潜在碳资源",CO2的分离和回收备受关注.与传统的CO2分离方法相比,膜分离技术具有不可比拟的优势.本文对近年来CO2选择透过无机膜、聚合物膜和促进传递膜等膜材料的制备方法及改性研究进行了综述,并对CO2选择性透过膜材料未来的发展进行了展望.     

致密皮层非对称气体分离膜的制备

以湿相转化法制备出分离性能优良的致密皮层非对称气体分离膜；建立了醋酸纤维素 丙酮 甲醇三组分制膜体系，所制得的致密皮层醋酸纤维素非对称气体分离膜，在室温、０５ＭＰａ进气压力下，该膜对ＣＯ２／ＣＨ４的分离系数３０，ＣＯ２透气速率可达１８×１０－８ｃｍ３（ＳＴＰ）／ｃｍ２·ｓ·Ｐａ；扫描电镜图显示该膜表层致密、超薄（约２００ｎｍ）、支持层疏松，为理想结构的非对称气体分离膜．     

The effects of transition metal complexes on the permeation of small gas molecules through cellulose acetate membranes

Cellulose acetate (CA) membranes containing RuCl₃·3H₂O and RhCl [P(C₆H₅)₃]₃ were prepared reproducibly. Such membranes, on treatment with CO, formed metal-carbonyl species at relatively low temperature. The Ru-carbonyls formed in CA were quite stable at 40°C in comparison with the Rh-carbonyl species and, interestingly, there was no permeation of CO gas through the ruthenium-containing CA membrane at 40°C. However, the permeation of other gas molecules, such as H₂, N₂ and O₂, through the same membrane was reduced only slightly, probably due to the cross-linking effect of the transition metal complexes in CA. It was found that essentially pure H₂ gas could be recovered from a 1: 1 mixture of H₂ and CO gases using ruthenium-containing cellulose acetate membranes.     

十七氟癸基修饰的有机-无机杂化二氧化硅膜材料的制备及气体分离性能

以十七氟癸基三乙氧基硅烷(PFDTES)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法制备了十七氟癸基修饰的SiO₂溶胶, 采用浸渍提拉法在γ-Al₂O₃/α-Al₂O₃多孔陶瓷支撑体上涂膜, 然后在N₂气氛保护下烧结成完整无缺陷的有机-无机杂化SiO₂膜. 利用扫描电子显微镜对膜材料的形貌进行观察, 通过动态光散射技术对溶胶粒径及分布进行测试, 利用视频光学接触角测量仪、 红外光谱仪和热分析仪表征了十七氟癸基修饰对有机-无机杂化SiO₂膜疏水性的影响. 结果表明, 十七氟癸基已经成功修饰到SiO₂膜材料中, 且随着PFDTES加入量的增大, 溶胶粒径和膜材料对水的接触角不断增大. 当n(PFDTES): n(BTESE)=0.25: 1时, 溶胶粒径分布较窄, 平均粒径为3.69 nm, 膜材料对水的接触角为(112.0±0.4)º. 在修饰后的有机-无机杂化SiO₂膜中H₂的输运遵循微孔扩散机理, 在300℃时, H₂的渗透率达到5.99×10^-7 mol·m^-2·Pa^-1·s^-1, H₂/CO和H₂/CO₂的理想分离系数分别达到9.54和5.20, 均高于Knudsen扩散的理想分离因子, 表明膜材料具有良好的分子筛分效应.     

Selective Permeation of CO2 Through Modified PVSA/PS Composite Membrane

Fixed carrier membranes are more favorable compared with the liquid membranes andion-exchange membranes, they can provide superior stability, high permeation rate andhigh selectivity1. Fixed carrier membrane for CO2 separation is a new research field,only…     

二氧化钛纳米粒子-氧化石墨烯/聚酰亚胺混合基质膜的原位聚合及气体渗透性能

以钛酸四丁酯为前驱体,采用浸渍-沉淀法制备二氧化钛纳米粒子-氧化石墨烯(TiO_2-GO)复合物,再将TiO_2-GO复合物与4,4'-(六氟异亚丙基)邻苯二甲酸酐和4,4'-二氨基二苯醚通过原位聚合构建TiO_2-GO/TiO_2-GO/PI(聚酰亚胺)混合基质膜,用于CO_2的渗透脱除.采用傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、热失重(TG)和Zeta电位等表征了TiO_2-GO复合物和TiO_2-GO/PI混合基质膜的形貌与结构;探讨了TiO_2掺杂量对TiO_2-GO复合物及TiO_2-GO/PI混合基质膜的结构和气体渗透性能的影响.结果表明,TiO_2-GO复合物中TiO_2纳米粒子较均匀地沉积在GO片层上,TiO_2纳米粒子在形成的同时破坏了GO的结构,使其无序度增加.TiO_2的掺杂对TiO_2-GO/PI混合基质膜的形貌与结构影响较小,但提升了TiO_2-GO/PI混合基质膜的CO_2和N2渗透性能.但过量的掺杂使TiO_2粒子在GO片层上团聚,从而导致TiO_2-GO复合物在混合基质膜中的分散性变差,CO_2渗透性及CO_2/N2渗透选择性降低.当TiO_2掺杂质量分数为30%时,TiO_2-GO/PI混合基质膜的CO_2渗透性为360 Barrer[1 Barrer=10~(-10)cm~3(STP)·cm/(cm~2·s·cm Hg)=7.5×10~(-14)cm~3(STP)·cm/(cm~2·s·Pa)],CO_2/N_2的渗透选择性可达31.     

Highly hydrothermally stable microporous silica membranes for hydrogen separation

Fluorocarbon-modified silica membranes were deposited on gamma-Al2O3/alpha-Al2O3 supports by the sol-gel technique for hydrogen separation. The hydrophobic property, pore structure, gas transport and separation performance, and hydrothermal stability of the modified membranes were investigated. It is observed that the water contact angle increases from 27.2+/-1.5 degrees for the pure silica membranes to 115.0+/-1.2 degrees for the modified ones with a (trifluoropropyl)triethoxysilane (TFPTES)/tetraethyl orthosilicate (TEOS) molar ratio of 0.6. The modified membranes preserve a microporous structure with a micropore volume of 0.14 cm3/g and a pore size of approximately 0.5 nm. A single gas permeation of H2 and CO2 through the modified membranes presents small positive apparent thermal activation energies, indicating a dominant microporous membrane transport. At 200 degrees C, a single H2 permeance of 3.1x10(-6) mol m(-2) s(-1) Pa(-1) and a H2/CO2 permselectivity of 15.2 were obtained after proper correction for the support resistance and the contribution from the defects. In the gas mixture measurement, the H2 permeance and the H2/CO2 separation factor almost remain constant at 200 degrees C with a water vapor pressure of 1.2x10(4) Pa for at least 220 h, indicating that the modified membranes are hydrothermally stable, benefiting from the integrity of the microporous structure due to the fluorocarbon modification.     

Fabrication of polymer/fluoride-containing salts blend composite membranes for CO_2 separation

Poly (N,N-dimethylaminoethyl methacrylate)-poly (ethylene glycol methyl ether methacrylate) (PDMAEMA-PEGMEMA) and cesium fluoride (CsF) were blended and used as the separation material of composite membranes.Hollow fiber composite membranes were fabricated by coating the blend on polysulfone (PSf) hollow fiber substrate.Introduction of fluorine ion improved the separation performance of the membrane.The concentration of coating solution was adjusted to obtain a membrane with high permeance.The composite membrane showed good performance with the CO2 permeance of 30.4 GPU (1 GPU=10-6 cm3 (STP)/(cm 2 s cmHg)),and selectivities to CO2/N2,CO2/CH4,CO2/H2 and O2/N2 of 47.2,37.6,1.75 and 4.70,respectively.Potassium fluoride (KF),due to its low cost,was also used as a substitute of CsF to prepare composite membrane and the permeation data showed that CsF can be replaced by KF.The effect of operating temperature on the permeation properties of the composite membrane was also investigated.     

中空纤维Au-CeZr/FAU催化膜的制备及在富氢气氛CO选择性氧化反应中的应用

采用浸渍法制备了一系列不同Ce/Zr掺杂比例的FAU分子筛膜, 并进一步负载纳米金, 制备了Au-CeZr/FAU催化膜. 对催化膜的微观形貌及结构进行了表征, 并对其在富氢气氛中催化CO优先氧化性能进行了研究. H₂-TPR结果表明, Ce/Zr掺杂比为1∶1时制得的催化膜Au-Ce₁Zr₁/FAU具有最好的被还原能力, 更有利于Au的分散与还原; O₂-TPD结果表明, 该样品的氧物种比其它样品上的氧物种活性更高. 更好的被还原性能和更高的氧物种活性使得制备的Au-Ce₁Zr₁/FAU催化膜性能最佳, 在60 ℃时CO转化率与O₂选择性可以同时达到100%, 并且在经过10次热循环测试后仍然可以保持稳定的催化性能.     

CO2／CH4分离膜及沸石填料影响渗透过程的研究

报导了甲基硅橡胶和纤维素（ＣＡ、ＣＴＡ、ＥＣ）膜对ＣＯ２、ＣＨ４的选择透气性能，并讨论了沸石作为填料所引起的分子筛作用的气体渗透过程。甲基硅橡胶的气体渗透系数最高，而选择性最低，且不受填料沸石的影响。纤维素膜的气体选择性较大，渗透系数可以通过沸石的加人而明显增加。特别是沸石１３Ｘ．沸石３Ａ、４Ａ、５Ａ在ＥＣ膜中对气体分子筛作用，改变了气体原有的渗透过程，提高了选择性。使用Ａｒｒｈｅｎｉｕｓ公式计算出ＥＣ－沸石３Ａ膜的气体渗透活化能。     

超临界CO_2诱导相转化法制备聚苯乙烯膜及膜体系的相图计算

以甲苯为溶剂,利用超临界CO_2诱导相转化法制备了多孔非对称聚苯乙烯膜.通过扫描电镜对膜结构进行了表征,探讨了不同温度、压力和铸膜液中聚苯乙烯浓度对膜形态、孔径分布及膜孔隙率的影响;同时,基于Tompa扩展的Flory-Huggins聚合物溶液理论计算了聚苯乙烯/超临界CO_2/甲苯铸膜体系的三元相图.研究表明,在温度为35~65℃、压力为8~16 MPa及聚合物质量分数为15%~35%条件下,制备的聚苯乙烯膜截面呈胞腔状孔结构,孔隙率为53.54%~84.67%,且孔隙率随温度、压力和聚苯乙烯浓度均呈现出先增大后减小的趋势.相图计算结果表明,温度对体系双节线位置的改变影响较小,而压力对其影响相对较大.     

Fabrication of polymer/fluoride-containing salts blend composite membranes for CO2 separation

Poly (N, N-dimethylaminoethyl methacrylate)-poly (ethylene glycol methyl ether methacrylate) (PDMAEMA-PEGMEMA) and cesium fluoride (CsF) were blended and used as the separation material of composite membranes. Hollow fiber composite membranes were fabricated by coating the blend on polysulfone (PSf) hollow fiber substrate. Introduction of fluorine ion improved the separation performance of the membrane. The concentration of coating solution was adjusted to obtain a membrane with high permeance. The composite membrane showed good performance with the CO2 permeance of 30.4 GPU (1 GPU = 10^-6 cm³(STP)/(cm²·s·cmHg)), and selectivities to CO2/N2, CO2/CH4, CO2/H2 and O2/N2 of 47.2, 37.6, 1.75 and 4.70, respectively. Potassium fluoride (KF), due to its low cost, was also used as a substitute of CsF to prepare composite membrane and the permeation data showed that CsF can be replaced by KF. The effect of operating temperature on the permeation properties of the composite membrane was also investigated.     

定向含硼MFI型沸石膜对纯气体的渗透性以及对乙醇/水体系的分离选择性

研究定向含硼MFI型沸石膜和原多孔玻璃基材对纯气体的渗透性以及对乙醇/水体系的分离选择性.原多孔玻璃基材对纯气体的透过表现出诺森扩散选择性,表明气体以诺森扩散通过.纯气体透过焙烧后的B-A1-ZSM-5沸石膜,H₂,He,Ne,Ar,O₂,CO₂对N₂的理想选择性分别为16.8,15.6,12.6,9.41,8.60,5.32;CO和SO₂对N₂的理想选择性分别为0.135和0.0179;O₂对CO和SO₂的理想选择性分别为63.7和480.2.这表明该类沸石膜对纯气体的透过不仅具有良好的理想选择性,而且可能为新型防毒面具提供一种很好的可选材料.渗透汽化实验表明,在测定温度范围内原多孔玻璃基材对三种不同浓度的乙醇/水体系几乎没有分离性能.焙烧后的B-A1-ZSM-5沸石膜对5 wt%,50wt%和95wt%乙醇/水体系的分离,水的最大分离系数分别为28.2,135.7和518.5,且温度均为303 K.表明该MFI型沸石膜具有强的亲水性.     

MICROPOROUS PVDF-HFP-BASED POLYMER MEMBRANES FORMED FROM SUPERCRITICAL CO2 INDUCED PHASE SEPARATION

Microporous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membranes following supercritical CO_2 induced phase separation process were prepared using four solvents.The solid electrolytes of PVDF-HFP were formed by microporous PVDF-HFP membranes filled and swollen by a liquid electrolyte.The effect of the solvents on the morphology and structure,electrolyte absorptions and lithium ionic conductivity of the activated membranes were investigated.It was approved that all the membrane had the simi...     

聚酰亚胺/SnO_2杂化膜的制备和表征及其气体渗透性测定

杂化材料作为一种新型材料结合了有机无机材料的优异特性，具有较高的热稳定性、机械强度和某些特殊的化学性质，在微电子、光电设备、传感器和分离膜等诸多领域得到应用与研究．溶胶凝胶法作为合成杂化材料的主要手段，具有反应条件温和，可通过调配反应参数来控制杂化材料的微观形态和性质等优点．     

Conventional processes and membrane technology for carbon dioxide removal from natural gas:A review

Membrane technology is becoming more important for CO 2 separation from natural gas in the new era due to its process simplicity,relative ease of operation and control,compact,and easy to scale up as compared with conventional processes.Conventional processes such as absorption and adsorption for CO 2 separation from natural gas are generally more energy demanding and costly for both operation and maintenance.Polymeric membranes are the current commercial membranes used for CO 2 separation from natural gas.However,polymeric membranes possess drawbacks such as low permeability and selectivity,plasticization at high temperatures,as well as insufficient thermal and chemical stability.The shortcomings of commercial polymeric membranes have motivated researchers to opt for other alternatives,especially inorganic membranes due to their higher thermal stability,good chemical resistance to solvents,high mechanical strength and long lifetime.Surface modifications can be utilized in inorganic membranes to further enhance the selectivity,permeability or catalytic activities of the membrane.This paper is to provide a comprehensive review on gas separation,comparing membrane technology with other conventional methods of recovering CO 2 from natural gas,challenges of current commercial polymeric membranes and inorganic membranes for CO 2 removal and membrane surface modification for improved selectivity.