Selective Removal of Carbon Dioxide from Wet CO2/H2 Mixtures via Facilitated Transport Membranes containing Amine Blends as Carriers

The selective separation of carbon dioxide (CO₂) from a wet gaseous mixture of CO₂/H₂ through facilitated transport membranes containing immobilized aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), ethylenediamine (EDA) and monoprotonated ethylenediamine (EDAH⁺) and their blends was experimentally investigated. The effect of CO₂ partial pressure, amine concentration, feed side pressure and amine species on the CO₂ and H₂ permeances were studied. The CO₂ permeability through amine solution membranes decreased with increasing CO₂ feed partial pressure but the H₂ permeance was almost independent of the H₂ partial pressure. A comparison of experimental results showed that single or blended amines with low viscosity and a moderate equilibrium constant, i.e., large forward and reverse reaction rate of CO₂‐amine, are suitable for effective separation of CO₂. The permeability of CO₂ generally increased with an increase in amine concentration, although this increase may be compromised by the salting out effect and decrease in diffusivities of species. The results obtained indicated that CO₂ permeance across a variety of amines are in the order of DEA (2 M) > MD (2 M) > MD (1 M) > MEA (2 M) > MEA (4 M) > MD (4 M) > DEA (1 M) > DEA (4 M) > MEA (1 M) for various concentrations of MEA + DEA blend and are in the order of EDAH⁺ (2 M) > DEA (2 M) > MH (2 M) > DH (2 M) > ED (2 M) > EDA (2 M) > MEA (2 M) for various blends of amine.     

用于CO2/CH4分离的cPIM-1/ZIF-8混合基质膜的制备

自聚微孔聚合物（PIM-1）虽具有良好的CO₂渗透性能,但其气体选择性普遍较差,限制其在CO₂/CH₄分离领域的应用。本文以N,N-二甲基甲酰胺（DMF）为溶剂制备ZIF-8纳米粒子,将其引入到羧基化的PIM-1基质中,制备了cPIM-1/ZIF-8混合基质膜,用于CO₂/CH₄分离。结果表明：由于合成ZIF-8的溶剂也是cPIM-1的良溶剂,使得两者之间具有良好的界面相容性,从而使ZIF-8添加量高达质量分数45%。随着ZIF-8添加量的增加,膜的CO₂渗透速率持续增加,CO₂/CH₄选择性呈现先上升后下降的趋势。当ZIF-8添加量为质量分数25%时,膜的CO₂/CH₄分离性能最好,即CO₂渗透系数为3942 Barrer,CO₂/CH₄选择性为18.7,较cPIM-1纯膜分别提高了 84%和43%,成功地超越了Robeson分离上限。     

Membranes for CO2 /CH4 and CO2/N2 Gas Separation

Membrane technology has emerged as a leading tool worldwide for effective CO₂ separation because of its well-known advantages, including high surface area, compact design, ease of maintenance, environmentally friendly nature, and cost-effectiveness. Polymeric and inorganic membranes are generally utilized for the separation of gas mixtures. The mixed-matrix membrane (MMM) utilizes the advantages of both polymeric and inorganic membranes to surpass the trade-off limits. The high permeability and selectivity of MMMs by incorporating different types of fillers exhibit the best performance for CO₂ separation from natural gas and other flue gases. The recent progress made in the field of MMMs having different types of fillers is emphasized. Specifically, CO₂/CH₄ and CO₂/N₂ separation from various types of MMMs are comprehensively reviewed that are closely relevant to natural gas purification and compositional flue gas treatment     

Asymmetric oxygen-functionalized carbon nanotubes dispersed in polysulfone for CO2 separation

Carbon dioxide separation from flue gases is an important challenge to be faced. Membrane processes are a promising alternative to increase technical and economical constraints once the development of materials with superior characteristics are attained. Integrally asymmetric mixed matrix membranes (MMMs) were prepared by dry/wet phase inversion process of polysulfone (PSF) containing oxygen-functionalized multiwalled carbon nanotubes (MWNT-O). Fourier transform infrared (FTIR) spectroscopy confirmed the presence of MWNT-O in MMMs. Thermal gravimetric analysis (TGA) showed that MMMs are stable up to 150°C. Photomicrographs from scanning electron microscopy (SEM) revealed that MMMs consist of an asymmetric structure with a skin layer supported on a sponge-like substructure. The pore size of the support of MMMs increased with MWNT-O content from 0.4 to 0.8 wt.% and the thickness of the dense layer decreased. However, when the content of MWNT-O increased to 1 wt.%, the pore size decreased, and the dense layer increased. Therefore, MMMs changed CO₂ separation performance. For 1 wt.% MWNT-O loading compared to the neat polymer, CO₂ permeance and CO₂/N₂ selectivity was increased from 1.5 to 2.7 GPU, and from 9.5 to 14.3, respectively.     

Metal-induced polymer framework membrane with high performance for CO2 separation

In this study, a novel porous material, that is, metal-induced polymer framework-1 (MPF-1) was synthesized using Zn(NO₃)₂·6H₂O and a high-molecular weight PVAmacid. MPF-1 has two structural advantages that help to create CO₂ separation membranes with simple fabrication procedure and high performance. First, MPF-1 is a high-molecular weight polymer with certain flexibility, and thus having good membrane-forming ability. Second, MPF-1 has small and uniform distributed pores, and contains amine groups those can react with CO₂ molecules reversibly. Therefore, CO₂ molecules can preferentially adsorb on pore walls of MPF-1 and transport across the pores by monomolecular surface diffusion, while most of N₂, CH₄, or H₂ molecules are excluded out the pores. The MPF-1 was employed to fabricate a microporous membrane by coating the MPF-1 dispersions on a polysulfone ultrafiltration membrane. CO₂ permeance and selectivity of the membrane keep almost unchanged with the feed pressure increasing from 0.11 to 1.0 MPa. © 2018 American Institute of Chemical Engineers AIChE J, 65: 239–249, 2019     

CO2/N2开关微乳液及其油污洗涤和分离性能

采用等摩尔的十二烷基苯磺酸钠与N-十二烷基-N,N-二甲基叔胺为主乳化剂,正丁醇为助乳化剂,正庚烷为油相,制得O/W型微乳液。在CO_2/N_2交替作用下,可实现微乳液-相分离-微乳液的可逆转换;原始微乳液与复原微乳液半径分别为(10.89±0.21)和(11.50±0.47)nm。该微乳液对多孔固体和织物表面烃类矿物油的洗油率分别为99.13%±0.32%和98.30%±0.28%,对油砂表面原油的洗油率为54.52%±0.25%。活性物质量分数相等时,微乳稀释液对织物表面油性记号笔渍的去污力是市售洗衣粉的1.90倍;而微乳原液的去污力是市售洗衣粉的2.02倍。洗后含油废液通入CO_2可迅速实现油水分层,分离油相后的残余水相经阴、阳离子交换树脂和活性炭常规处理,COD和TOC分别为40.62和17.51 mg/L,符合GB 18918-2002中一级水排放标准(COD≤100 mg/L,TOC≤20 mg/L)。     

叔胺基CO2开关表面活性剂的合成及性能研究

以不同碳链长度的脂肪酸(n=12,14和16)和N,N-二甲基-1,3-丙二胺为原料合成了系列长链脂肪酰胺叔胺C_nAMPM。通过核磁共振氢谱和电导率实验证实了其CO_2开关响应性能。研究发现:通入CO_2后,CnAMPM表现出表面活性剂特征,随着碳链长度增加,cmc线性降低,发泡性能、乳化正庚烷的能力和在标准帆布上的润湿性能也相应下降。通入N_2后,发泡力大幅度降低;C_(12)AMPM的乳化性能较好,润湿性能好于另外2种;而C_(14)AMPM和C_(16)AMPM的乳化能力和润湿能力均较差。     

Adsorption and separation of CO2/N2 and CO2/CH4 by 13X zeolite

Accumulation of greenhouse gases in the atmosphere is responsible for increased global warming of our planet. The increasing concentration of carbon dioxide mainly from flue gas, automobile and landfill gas (LFG) emissions are major contributors to this problem. In this work, CO₂, CH₄ and N₂ adsorption was studied on Ceca 13X zeolite by determining pure and binary mixture isotherms using a constant volume method and a concentration pulse chromatographic technique at 40 and 100°C. The experimental data were then compared to the predicted binary behaviour by extended Langmuir model. Results showed that the extended Langmuir theoretical adsorption model can only be applied as an approximation to predict the experimental binary behaviour for the systems studied. Equilibrium phase diagrams were obtained from the experimental binary isotherms. For these systems, the integral thermodynamic consistency tests were also conducted. It was found that Ceca 13X exhibits large CO₂/CH₄ and CO₂/N₂ selectivity and could find application in landfill gas purification, CO₂ removal from natural gas and CO₂ removal from ambient air or flue gas streams. © 2011 Canadian Society for Chemical Engineering     

CO2/N2 separation using supported ionic liquid membranes with green and cost-effective [Choline][Pro]/PEG200 mixtures

The high price and toxicity of ionic liquids(ILs) have limited the design and application of supported ionic liquid membranes(SILMs) for CO_2 separation in both academic and industrial fields. In this work, [Choline][Pro]/polyethylene glycol 200(PEG200) mixtures were selected to prepare novel SILMs because of their green and costeffective characterization, and the CO_2/N_2 separation with the prepared SILMs was investigated experimentally at temperatures from 308.15 to 343.15 K. The temperature effect on the permeability, solubility and diffusivity of CO_2 was modeled with the Arrhenius equation. A competitive performance of the prepared SILMs was observed with high CO_2 permeability ranged in 343.3–1798.6 barrer and high CO_2/N_2 selectivity from 7.9 to 34.8.It was also found that the CO_2 permeability increased 3 times by decreasing the viscosity of liquids from 370 to38 m Pa·s. In addition, the inherent mechanism behind the significant permeability enhancement was revealed based on the diffusion-reaction theory, i.e. with the addition of PEG200, the overall resistance was substantially decreased and the SILMs process was switched from diffusion-control to reaction-control.     

Study on CO2 facilitated separation of mixed matrix membranes containing surface modified MWCNTs

Mixed matrix membranes (MMMs) for CO₂-facilitated separation were prepared by incorporating different surface-modified multiwalled carbon nanotubes (MWCNTs) in a fixed carrier membrane material. Polymer containing amino groups, poly(vinylalcohol-co-vinylamine) (VA-co-VAm) was synthesized as polymeric matrix. MWCNTs as well as MWCNTs surface-modified with  OH and  NH₂ were applied as nanofillers. The physical property, chemical structure, and membrane morphology were characterized by FT-IR, TG, XRD, DSC, CA, XPS, and SEM. The effects of content, functional group, temperature, and pressure on gas permselectivity were studied. Results show that the incorporation of nanofillers can effectively restrict the polymer chain packing and lead to low crystallinity. The MMMs exhibited higher CO₂ permselectivity than the pure polymeric membrane. For all the MMMs, the CO₂ permeance and selectivity increased with MWCNTs contents to a maximum and then decreased. MWCNT-NH₂ can be regarded as the most effective nanofiller. MMMs with 2.0 wt % MWCNT-NH₂ displayed the highest CO₂ permeance of 132 GPU and CO₂/N₂ selectivity of 74. Both CO₂ permeance and selectivity were decreased with feed gas pressure and temperature. The membrane exhibited good stability in the testing with the binary gas mixtures of CO₂/N₂ for 110 h under 0.54 MPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47848.     

Dual-phase membrane reactor for hydrogen separation with high tolerance to CO2 and H2S impurities

Catalytic membrane reactors based on oxygen-permeable membranes are recently studied for hydrogen separation because their hydrogen separation rates and separation factors are comparable to those of Pd-based membranes. New membrane materials with high performance and good tolerance to CO₂ and H₂S impurities are highly desired. In this work, a new membrane material Ce_0.85Sm_0.15O_1.925–Sr₂Fe_1.5Mo_0.5O_6-δ (SDC–SFM) was prepared for hydrogen separation. It exhibits high conductivities at low oxygen partial pressures, which is benefit to electron transfer and ion diffusion. A high hydrogen separation rate of 6.6 mL cm⁻² min⁻¹ was obtained on a 0.5-mm-thick membrane coated with Ni/SDC catalyst at 900°C. The membrane reactor was operated steadily for 532 h under atmospheres containing CO₂ and H₂S impurities. Various characterizations reveal that SDC–SFM has good stability in the membrane reactor for hydrogen separation. All facts confirm that SDC–SFM is promising for hydrogen separation in practical applications. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1088–1096, 2019     

Enhanced CO2 separation performance of mixed matrix membrane by incorporating amine-functionalized silica filler

Mixed matrix membranes (MMMs) owing to the tunable characteristics and functionalization ability can effectively substitute the highly intensive conventional membranes for industrial-scale CO₂ separation. Further, to strengthen the interfacial polymer-filler interaction, an interfacial design strategy incorporating active functional groups in the filler surface can be demonstrated. In this study, as-synthesized silica nanoparticles (SNPs) was surface functionalized by (3-aminopropyl) trimethoxysilane silica modifier (AFSNP). The CO₂ separation of poly (vinyl alcohol)/polyethylene glycol based MMM infused with surface-functionalized SNP (AFSNP) was conducted. The comparative study highlighted in-depth analysis of intrinsic physicochemical properties of as-synthesized membranes and nanoparticles. Detailed characterization such as advanced microscopic analysis, X-ray photoelectron spectroscopy (XPS) analysis and ninhydrin assay validated the successful grafting of amino groups onto the silica surface. The morphological inspection corroborated the consistent dispersion ability of the nanoparticles in the membrane matrix. The effect of the operating conditions on the membrane selectivity and CO₂ permeance were statistically analyzed by ANOVA. The CO₂ permeation result (CO₂ permeance and CO₂/N₂ selectivity) exhibited many fold increment with surface functionalization of SNPs compared to undoped silica MMM. The defect-free, performance-oriented CO₂-selective membrane thus opened up the possibility of this combination as a prospective contender for large-scale carbon capture studies.     

CO2 separation performance by chitosan/tetraethylenepentamine/poly(ether sulfone) composite membrane

CO₂ separation from CO₂/N₂ (20:80) gas mixture has been demonstrated by tetraethylenepentamine blended with chitosan (CS‐TEPA) membrane. Optimization of CS and TEPA weight ratio were carried out based on characterization details involving thermogravimetric analysis, Fourier transform infrared spectroscopy, X‐ray diffraction, atomic force microscope, and field emission scanning electron microscope. Effects of water flow rate, pressure, and temperature were concurrently studied on CS‐TEPA membranes through gas permeation. Almost twofold increase in CO₂ permeance (24.7 GPU) was detected in CS blend with 30% (w/w) of TEPA (CS70) as compared to pure CS membrane (12.5 GPU). CS70 yielded CO₂/N₂ selectivity of 80 whereas CS demonstrated a maximum of 54 at 90 °C. The membrane also exhibited improved stability at temperatures less than 120 °C which was evident from TGA isotherm trace. The proposed composite membrane can be a promising candidate for flue gas separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45206.     

High-speed CO2 transport channel containing carboxymethyl chitosan/hydrotalcite membrane for CO2 separation

A comprehensive understanding of carboxymethyl chitosan (CMC)-based mixed matrix membrane (MMM) has been critically investigated. The present work elaborates the compatibility of hydrotalcite (HT) and CMC in terms of CO₂ separation application. Various spectroscopic and microscopic techniques have been utilized to characterize the respective properties of the prepared membrane. The temperature stability and moisture retention behavior of the membrane recognized itself as the flue gas separation membrane. The CO₂/N₂ separation experiment was performed on the MMM at different temperature (60–110 °C) and sweep/feed water flow to the saturator ratio (0.33 to 3). The membrane exhibited the optimum CO₂ permeance of 70 GPU at 90°C pertaining to water flow ratio of 2.33 (sweep/feed). The CO₂/N₂ selectivity observed at that same operating condition was 13. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48715.     

Pebax/a-MoS2/MIP-202混合基质膜的制备及CO2分离性能

为了获得高性能的CO₂/N₂分离膜,把空气中氧刻蚀的二硫化钼（a-MoS₂）和金属有机框架材料MIP-202通过机械力化学反应制备的双功能填料作为分散相,聚醚嵌段酰胺（Pebax-1657）作为连续相,采用溶液浇铸法制备了Pebax/a-MoS₂/MIP-202混合基质膜。采用FT-IR表征了填料的化学结构,借助ATR-FTIR、SEM、TG和力学性能测试表征了混合基质膜的化学结构、微观形貌结构、热稳定性和物理力学性能。研究了水含量、双功能填料配比、含量、膜两侧压差和操作温度对膜气体分离性能的影响,并考察了模拟烟道气（CO₂/N₂体积比15/85）条件下混合基质膜的长时间运行稳定性。结果表明：在温度为25℃、膜两侧压差为0.1 MPa的操作条件下,a-MoS₂与MIP-202质量比为5∶5和双功能填料含量为6%（质量）时,膜的气体分离性能达到最优,CO₂渗透性和CO₂/N₂选择性分别为380 Barrer和124.7,超过了2019年McKeown等提出的上限值。连续测试360 h后,混合基质膜的性能没有明显降低,其平均CO₂渗透性和CO₂/N₂选择性分别为358 Barrer和120.1。这主要是由于a-MoS₂和MIP-202协同提高了膜的气体分离性能。     

Pebax/a-MoS2/MIP-202混合基质膜的制备及CO2分离性能

为了获得高性能的CO₂/N₂分离膜,把空气中氧刻蚀的二硫化钼（a-MoS₂）和金属有机框架材料MIP-202通过机械力化学反应制备的双功能填料作为分散相,聚醚嵌段酰胺（Pebax-1657）作为连续相,采用溶液浇铸法制备了Pebax/a-MoS₂/MIP-202混合基质膜。采用FT-IR表征了填料的化学结构,借助ATR-FTIR、SEM、TG和力学性能测试表征了混合基质膜的化学结构、微观形貌结构、热稳定性和物理力学性能。研究了水含量、双功能填料配比、含量、膜两侧压差和操作温度对膜气体分离性能的影响,并考察了模拟烟道气（CO₂/N₂体积比15/85）条件下混合基质膜的长时间运行稳定性。结果表明：在温度为25℃、膜两侧压差为0.1 MPa的操作条件下,a-MoS₂与MIP-202质量比为5∶5和双功能填料含量为6%（质量）时,膜的气体分离性能达到最优,CO₂渗透性和CO₂/N₂选择性分别为380 Barrer和124.7,超过了2019年McKeown等提出的上限值。连续测试360 h后,混合基质膜的性能没有明显降低,其平均CO₂渗透性和CO₂/N₂选择性分别为358 Barrer和120.1。这主要是由于a-MoS₂和MIP-202协同提高了膜的气体分离性能。     

Synthesis of dual-functionalized mixed matrix membrane with amino-GO-Bent/PVDF for efficient separation of CO2/CH4 and CO2/N2

Mixed matrix membranes (MMMs), which combine the characteristics of inorganic nanofillers and organic matrices, have received wide attention because of their good permeability and selective performance for separating CO₂ from industrial waste gases. In this work, the amino-GO-loaded bentonite (amino GO-Bent) was prepared by loading  NH₂ on the GO surface with a large number of functional sites. Firstly, by introducing  NH₂ on the surface of GO and then interacting with bentonite (Bent) organically modified by silane coupling agents through amide bonding. Mixed matrix membranes (MMMs) with an area of 623.7 cm² and homogeneous texture were prepared using amino-GO-Bent as inorganic filler to improve the membrane selectivity for CO₂/N₂ and CO₂/CH₄ separation. The results show that the introduction of amino GO-Bent in MMMs can greatly improve the CO₂ permeability and obtain high CO₂ permeation performance: 2.67945 × 10⁻⁷ cm³ (STP)·cm/s/cm²/cmHg, and the selectivity of CO₂/N₂ and CO₂/CH₄ can reach 307.28 and 325.97, respectively. The two selective values were 14 and 18 times higher than those of pure PVDF membranes, and the performance of MMMs far exceeded the Robeson upper limit in 2008, respectively.     

Synthesis and characterization of diethanolamine-impregnated cross-linked polyvinylalcohol/glutaraldehyde membranes for CO2/CH4 separation

In this research, the cross-linking of diethanolamine (DEA) impregnated poly(vinyl alcohol) (PVA) on polytetrafluoroethylene (PTFE) by glutaraldehyde (GA) with different blend compositions (GA/PVA: 0.5, 1, 3, 5, 7 ratio%) was performed in the absence of an acid catalyst and organic solvents in order to avoid any interference in CO₂ facilitation reaction with DEA. The fabricated membranes were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Furthermore, the effects of cross-linking agent content, feed pressure and composition as well as stability on CO₂/CH₄ transport properties were investigated in both pure and mixed gas experiments. The cross-linked membranes showed reasonable CO₂/CH₄ permselectivities in comparison with uncross-linked membranes. The best-yield CO₂-selective membranes (DEA-PVA/GA(1 wt%)/PTFE) represented the best CO₂/CH₄ selectivity of 91.13 and 665 for pure and mixed gas experiments, respectively.     

用于燃烧后CO2捕集系统的胺基固态吸附材料研究进展

随着工业化的发展和大量化石燃料的消耗,大量的CO₂气体排放到大气中并引发了一系列严重的环境问题,而采用燃烧后CO₂捕集技术可以有效地应对这一问题。寻找一种高效吸附、稳定、价格低廉的固态吸附材料对于开展燃烧后CO₂捕集系统的研究具有重要的实际意义。近年来,胺基固态吸附材料因其高CO₂吸附能力和高吸附选择性成为研究的热点。本文综述了近年来国内外学者对不同胺基固态吸附材料在合成方法、载体材料选择以及性能测试等方面进行的研究,重点讨论了以沸石分子筛、介孔硅分子筛、多孔碳和金属有机骨架为载体的胺基固态吸附材料对CO₂的吸附行为,并指出多孔载体材料的结构改进及有机胺和促进剂的合理选择将会成为未来胺基固态吸附材料的重点研究方向。