Zeolite Mixed Matrix Membranes Research Articles

Pervaporative poly(vinyl alcohol)/H‐β zeolite mixed matrix membranes for dewatering C2–C3 alcohols

AbstractIn present work, mixed matrix membranes (MMMs) of poly(vinyl alcohol) (PVA) and porous H‐β zeolite have been thoroughly studied for concentrating ethanol, n‐propanol and isopropanol aqueous solutions via dewatering pervaporation. The effects of the zeolite content, feed composition and temperature on pervaporation flux/separation factor and permeance/selectivity are examined in detail for three alcohols. Experimental results show the H‐β zeolite addition has achieved more pronounced permeation flux and better separation efficiency than pure PVA counterpart, mainly attributed to the zeolitic pore size and hydrophilic feature. The MMMs have led to satisfactory permeation flux and separation factor and these results may be analyzed from the perspectives of the driving force, Hansen solubility parameter parameters and Flory–Huggins interaction parameter. The separation factor generally follows the sequence of isopropanol > n‐propanol > ethanol according to the reverse order of their molecular sizes and polarities. The MMM of 20 wt% zeolite loading has performed stably over 144 h at 60°C, and achieved separation factors of 1204, 1391, and 1645 and total fluxes of 719, 702, and 684 g/m2 h from the 10 wt% water feed for isopropanol, n‐propanol and ethanol, respectively. Therefore, the PVA/H‐β zeolite MMMs are technologically promising for alcohol dehydration applications.

Pervaporation of hydrazine/water with ethylcellulose/4A zeolite mixed matrix membranes

Pervaporation of hydrazine/water with ethylcellulose/4A zeolite mixed matrix membranes

Experimental and Numerical Study of CO2/CH4 Separation Using SAPO-34/PES Hollow Fiber Membrane

The poor compatibility between polymeric matrix and inorganic filler in mixed matrix membrane (MMM) generates interfacial defects that reduce the gas selectivity. In this work, the defects in poletherysulfone (PES)/silicoaluminophosphate (SAPO)-34 zeolite mixed matrix membrane was prepared by dry–wet spinning technique for the separation of CO2/CH4 mixtures. In this regard, the synthesized PES/SAPO-34 mixed matrix membranes (MMMs) were characterized via FESEM, TGA and DSC analyses. The response surface methodology (RSM) was applied to find the relationships between several explanatory variables such as air gap distance, jet strech ratio and zeolite content and CO2 permeance as responses. The results were validated with the experimental data, which the model results were in good agreement with the available experimental data. The effects of feed temperature and feed pressure on permeation and CO2/CH4 selectivity of membranes were investigated. The MMMs showed better performance than the neat PES membrane. Two dimensional countercurrent mathematical model for membrane separation has been incorporated with Aspen HYSYS as a user defined unit operation in order to optimize and design the membrane system for CO2 capture from natural gas. Parameter sensitivities, along with process economics, have been studied for different design configurations (including recycle streams and multiple stages). It has been observed that double stage with permeate recycle system gives the optimum design configuration due to minimum process gas cost involved with it. Permeation results manifested that the PES/SAPO-34 fabricated at optimum conditions has incredible worth from the prospective of industrial separations of CO2 from flue and natural gas.

Mixed Matrix Membranes prepared from polysulfone and Linde Type A zeolite

Abstract This work focuses on dip coating and further phase inversion prepared polysulfone/LTA zeolite mixed matrix membranes (MMMs). The Linde Type A (LTA) zeolite synthesized under hydrothermal conditions by the organic free method was introduced as fillers at 10 and 20 wt.% loadings into the polysulfone polymer matrix to obtain MMMs. The x-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis indicated that the as-synthesized LTA zeolite samples were crystalline and mainly composed of crystal of predominantly cubic shape. Textural characterisation using Ar adsorption/desorption data of LTA zeolite shown the existence of mesoporous. Atomic force microscopy (AFM) in combination with the SEM characterised the membrane morphology and the dispersion of zeolite fillers. The effect of the zeolite loading on the performance of the MMMs was analysed. It points out that N2 permeability was increased with the increment of zeolite filler, also the high membranes permeability and the weak dependence upon transmembrane pressure and therefore its high selectivity. The average membrane thickness was 150 μm.

Preparation and Characterization of PIM-1/Modified Zeolite Mixed Matrix Membranes for CO2/N2 Separation

Mixed matrix membranes (MMMs) of polymer of intrinsic microporosity (PIM-1) is synthesized by incorporating modified zeolite (MZ) as the filler. Zeolite was treated with (3-Aminopropyl)-triethoxysilane (APTES). This treatment provided terminal amino groups to the zeolite by interaction between zeolite and ethoxy group of silane. MZ was systematically incorporated from 5 wt% to 15 wt% for evaluation of the improvement in gas separation behaviour. Physical characteristics and elemental analysis of MMMs were evaluated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectrum indicated physical interaction between PIM-1 and MZ. Scanning electron microscopy analysis (SEM) revealed the smooth surface morphology for PIM-1 membrane. Aggregates of MZ were observed from SEM analysis of PIM-1/MZ MMMs which indicated the formation of additional void volume. The Brunauer, Emmett, Teller (BET) analysis exhibited type I isotherm for PIM-1. The PIM-1 surface area was calculated to be 656 m2 g-1. Thermogravimetric analysis (TGA) revealed that membranes are thermally stable up to 460 ᴼC. Gas separation behaviour of MMMs was also evaluated with particular focus on CO2 /N2 separation. Permeability was observed to increase with increasing filler concentration. CO2 permeability was evaluated to increase from 2610 barrer for PIM-1 membrane to 5540 barrer for PIM-1/MZ MMM (15 wt%). Tremendous increase in permeability was observed for alcohol treated PIM-1/MZ MMMs. Aging analysis was performed by calculating the permeability for each membrane after 30, 60 and 90 days.

Preparation and characterization of poly(vinylidene fluoride)‐13X zeolite mixed matrix membranes for lithium ion batteries' separator with enhanced performance

Abstract13X zeolite was hydrothermally synthesized and poly(vinylidene fluoride) (PVDF)/13X zeolite particles mixed matrix membranes were prepared using phase inversion method as the lithium‐ion battery separator. Hydrophilic and porous 13X zeolite loading impacts on the critical separator properties of morphology, wettability, electrolyte uptake, and high temperatures dimensional stability were investigated using scanning electron microscopy, contact angle, and thermal shrinkage analysis. Electrolyte uptake of the 13X zeolite particles loaded PVDF separators increased and also the incorporation facilitated the lithium ions migration (ion conductivity) due to the Lewis acidity of their structure. The 8 wt% 13X zeolite loaded separator (S2) revealed higher porosity (~+20%), electrolyte uptake (+80%), ion conductivity (+80%), and thermal shrinkage (~−47% at 165°C). C‐rate capability and cycle performance of a cell battery assembled using the S2 separator considerably improved compared with those of the assembled by the neat PVDF and commercial polypropylene separators.

Novel N-p-carboxy benzyl chitosan/poly (vinyl alcohol/functionalized zeolite mixed matrix membranes for DMFC applications

The novel N-p-carboxy benzyl chitosan (CBC)/ poly (vinyl alcohol) (PVA) based mixed matrix membranes (MMMs) filled with surface-modified zeolite have been prepared using the dissolution casting technique. The applicability of prepared MMMs for direct methanol fuel cell (DMFC) was investigated in terms of water uptake, methanol permeation, and proton conductivity by changing filler content (10−50 wt. %). The zeolite was modified by silane coupling agent, 3-mercaptopropyltrimethoxysilane (MPTMS). The resultant modified zeolite (MZ) was incorporated into CBC/PVA blend to obtain mixed matrix PEMs. The functional group, structural properties, morphological and topographical investigation of MMMs were examined using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) respectively. The prepared MMMs exhibited a remarkable decrease in methanol permeability of 2.3 × 10−7 cm2/s with C-CPMZ50. The maximum value of proton conductivity of 0.0527 Scm−1, was shown by C-CMPZ10. The prepared PEMs also displayed good stability during long term operating time.

Effects of solvent and ionic liquid properties on ionic liquid enhanced polysulfone/SAPO-34 mixed matrix membrane for CO2 removal

Abstract The poor compatibility between polymeric matrix and inorganic filler in mixed matrix membrane (MMM) generates interfacial defects that reduce the gas selectivity. In this work, the defects in polysulfone (PSf)/silicoaluminophosphate (SAPO)-34 zeolite mixed matrix membrane was post-treated using three types of ionic liquid with CO2 affinity. The effects of solvent (methanol and ethanol) and ionic liquid used in modification on membrane properties and CO2 removal was studied. The presence of ionic liquid in the modified MMM was confirmed in Fourier-transform infrared spectroscopy analysis. The CO2/N2 selectivity of the MMM was enhanced more than 700% after being treated using 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) ionic liquid solution in methanol. The solvent polarity could affect the solubility and mobility of ionic liquid during modification. When 1-ethyl-3-methyl imidazolium bis(tri-fluoromethylsulfonyl)imide ([emim][Tf2N]) ionic liquid was used, the CO2/N2 selectivity and CO2 permeance could be further increased to 44.9 and 7.19 GPU, respectively.

Poly(vinyl alcohol)/ZSM-5 zeolite mixed matrix membranes for pervaporation dehydration of isopropanol/water solution through response surface methodology

Mixed matrix membranes (MMMs) of poly(vinyl alcohol) (PVA) containing certain amounts of ZSM-5 zeolite were evaluated for pervaporation dehydration of highly concentrated isopropanol aqueous solution. The effects of zeolite content, feed composition and feed temperature on the membrane separation performance are in detail examined by using a preliminarily one-factor-each time method and a systematically response surface methodology (RSM). Preliminarily results show the dehydration separation factor/selectivity have been greatly boosted but without the cost of pervaporation flux/permeance after adding zeolite ZSM-5, and it is consistent very well with the Arrhenius activation energy estimations where water molecules require much less energy whereas ethanol molecules need much more energy to transport through the membrane, probably because of the favorable hydrophilic and porous features of zeolite ZSM-5 as revealed by swelling and water contact angle results. High feed isopropanol concentration and low feed temperature are both observed to lead to very low pervaporation flux/permeance but very relatively high separation factor/selectivity. The RSM results suggest that zeolite content, feed composition and feed temperature all have highly significant impacts on total pervaporation flux and separation factor. The interaction effect of zeolite content and feed temperature on separation factor is for the first time found to be also significant. The polynomial models established according to the RSM analysis can fit very well against the experimental data with a very high coefficient of determination and the predictions given for optimized conditions have been experimentally confirmed by the validation results with a deviation of less than 2.0%.

Effective hydrogen purification from methane via polyimide Matrimid® 5218- Deca-dodecasil 3R type zeolite mixed matrix membrane

Abstract The demand for purified hydrogen as a new green energy source has dramatically increased during last years. In this study, different -Matrimid®- Deca-dodecasil 3R (DDR) type zeolite mixed matrix membranes were synthesized for Hydrogen purification from Methane. Results demonstrated that existence of DDR into the Matrimid® matrix, as well as, high temperature thermal treatment enhances membrane crystallinity. Scanning electron microscope images of membranes showed uniform dispersion of zeolite in polymer matrix and well contact at polymer and zeolite interface. Gas permeation experiments exhibits that due to molecular sieving effect of DDR membrane Hydrogen permeabilities and Hydrogen/Methane selectivity enhance for 20 wt % loading of Deca-dodecasil 3R to 34.90 Barrer (100%) and 375.27 (189%), respectively.

Preparation and characterization of polysulfone/zeolite mixed matrix membranes for removal of low-concentration ammonia from aquaculture wastewater.

Removal of low-concentration ammonia (1-10 ppm) from aquaculture wastewater was investigated via polysulfone (PSf)/zeolite mixed matrix membrane. PSf/zeolite mixed matrix membranes with different weight ratios (90/10, 80/20, 70/30 and 60/40 wt.%) were prepared and characterized. Results indicate that PSf/zeolite (80/20) was the most efficient membrane for removal of low-concentration ammonia. The ammonia elimination by PSf/zeolite (80/20) from aqueous solution for 10, 7, 5, 3 and 1 ppm of ammonia was 100%, 99%, 98.8%, 96% and 95% respectively. The recorded results revealed that pure water flux declined in higher loading of zeolite in the membrane matrix due to surface pore blockage caused by zeolite particles. On the other hand, ammonia elimination from water was decreased in higher contents of zeolite because of formation of cavities and macrovoids in the membrane substructure.

In situ carbon deposition in polyetherimide/SAPO‐34 mixed matrix membrane for efficient CO2/CH4 separation

ABSTRACTA simple method of pore modification complied with defect removal polymer zeolite mixed matrix membrane was developed by in situ carbon (C) deposition. The C deposition was achieved by the controlled decomposition of polymer matrix by heat treatment. In this study, polyetherimide/silicoaluminophosphate‐34 mixed matrix membrane (MMM) was fabricated on clay‐alumina support tube, followed by carbonization of the polymer matrix for gas separation application. MMM without heat treatment were also synthesized for comparison by conventional method. The membranes were characterized by X‐ray diffraction, field emission scanning electron microscopy, and X‐ray photoelectron spectroscopy. Due to carbonization, in situ C nanoparticles were deposited in to the interfacial pores, and filler particles were oriented in preferable direction. The presence of CO, CN, and graphitic carbon in the matrix, may be an indication of partial carbonization and restoration of adherence of polymer with substrate. The separation factor for CO2/CH4 achieved 39.15 with a permeance value of 23.01 × 10−8mol/(m2 s Pa) for CO2 at 30 °C and 200 kPa feed pressure. For the first time, this work shows an improvement toward permeability of MMM by simple carbonization of polymer matrix with commendable values as compare to the reported literature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45508.

Molecular simulation and Monte Carlo study of structural-transport-properties of PEBA-MFI zeolite mixed matrix membranes for CO 2 , CH 4 and N 2 separation

In this communication, structural-transport-properties of polyether block amide (PEBA)-MFI zeolite mixed matrix membranes (MMMs) have been investigated with molecular simulation (MS) and Monte Carlo (MC) technique. The density profile, RDF, FFV and XRD characterization have been calculated to investigate the aforementioned MMMs microstructure and also sorption and diffusion structural dependence of CO2–CH4 and CO2–N2 pairs. Sorption, diffusion, permeability and selectivity of natural gases including CO2, CH4 and N2 by PEBA polymeric membrane filled with nano-zeolite (MFI type) have been examined to study the influence of MFI nanomaterial and nanomaterial loading content on the performance of the MMMs. By increase of MFI loading from 10 to 20 wt.%, permeability for CO2, CH4 and N2 increases from 106.5 to 123.6, 4.75–4.74 and 1.28 to1.31, respectively. Structural analysis shows very good behavior for simulated membranes. Moreover, experiments show that simulation results for XRD and diffusivity are in good agreement with experiment results.

Modification of gas selective SAPO zeolites using imidazolium ionic liquid to develop polysulfone mixed matrix membrane for CO2 gas separation

Ionic liquids (ILs) with high CO2 solubility and selectivity have been extensively studied in recent years to improve the performance of CO2 separation membranes. The progress in the development of supported IL membranes, polymerized IL membrane, polymer/IL gel membranes and membrane gas absorption using IL is limited by the high viscosity and price of ILs. In this work, the gas selective SAPO-34 zeolite was modified using [emim][TF2N] IL before the zeolites were incorporated into polysulfone (PSf) asymmetric membrane which was prepared by phase inversion. The main objective of this work is to study the effects of immersion duration on the IL-functionality of zeolite, membrane morphology and gas separation properties of PSf/SAPO-34 zeolite mixed matrix membrane. The incorporation of IL into the SAPO zeolite was confirmed by energy dispersive X-ray analysis. This analysis also proved the well dispersion of SAPO-34 particles with IL modification for 6 h due to the improved polymer/filler interface morphology as shown by scanning electron microscopy analysis. The gas separation test further revealed that the membrane containing SAPO-34 modified with IL for 6 h showed a great enhancement in both CO2/CH4 and CO2/N2 selectivity (approximately 486% and 232% respectively) over the unmodified mixed matrix membrane.

Fabrication of Foamed Polyethersulfone–Zeolite Mixed Matrix Membranes for Polymer Electrolyte Membrane Fuel Cell Humidification

Polymer electrolyte membrane (PEM) fuel cell efficiency must be improved in order to become cost competitive with fossil fuel-based technologies. Approaches to increasing cost efficiency include raising fuel cell operating temperature, reducing component cost, and properly controlling fuel cell humidification. We sought to fulfill all three requirements by developing a new low-cost, high-temperature humidification membrane material. Currently, Nafion dominates the membrane humidifier market due to its excellent water transport characteristics, but its high price (∼$1000/m2) and low maximum operating temperature (<90 °C) drive up fuel cell cost. We developed a competing polyethersulfone (PES)–zeolite mixed matrix membrane (MMM) with a porous microstructure. Solvent casting was used to form the initial PES–zeolite films, followed by solid-state foaming to alter the film morphology and create a porous structure. The effects of both zeolite weight loading and foaming duration on membrane permeability were investigated. Membrane measurement results show that both foaming and increased zeolite weight loading enhance membrane water permeability close to levels seen in Nafion. Meanwhile, the membranes satisfy the Department of Energy (DOE) crossover gas requirement for humidification membrane materials.

The Gas Separation Performance of Polyurethane–Zeolite Mixed Matrix Membranes

ABSTRACTThe effect of zeolite 3A, 4A, and ZSM‐5 on the gas separation performance of polyurethane (PU)–zeolite mixed matrix membranes (MMMs) has been investigated in this study. Permeation of pure CO2, CH4, N2, and O2 gases through PU–zeolite MMMs with zeolite content of 6, 12, 18, and 24 wt% was studied. The prepared hybrid membranes were characterized using Fourier transform infrared spectroscopy and scanning electron microscope. Membrane characterization confirmed the homogeneous distribution of zeolite particles at low zeolite loadings in the prepared membranes. The obtained results confirmed a significant enhancement in the permeability of all gases and the CO2/N2, CO2/CH4, and O2/N2 selectivities by increasing the content of zeolite particles in PU–zeolite MMMs. The PU–zeolite 4A with 12 wt% zeolite loading showed the best performance in terms of gas permeability and selectivity for CO2/N2, CO2/CH4 and O2/N2 gas pairs.

An approach to prepare defect-free PES/MFI-type zeolite mixed matrix membranes for CO2/N2 separation

Polyethersulfone (PES) and MFI-type zeolite mixed matrix membranes (MMMs) were successfully fabricated by a novel particle suspension impregnating and solution-casting method. The effects of two different membrane preparation methods on the membrane morphology were investigated by scanning electron microscopy; the particle crystal type and distribution were explored by X-ray diffraction and fourier transform attenuated total reflectance infrared spectroscopy. The results showed that the MFI-zeolite particles were successfully synthesized, with particle diameter around 250 nm. Distribution and dispersion of MFI-zeolite particles suspended in the polymer matrix are homogeneous and uniform. The thermal analysis indicates that the glass transition temperature (Tg) of MMMs is around 230 °C and the initial degradation temperature is up to 460 °C in air. The increment of Tg compared to the neat PES confirms that the polymer chain rigidification is induced by zeolite particles. The MMMs have been evaluated by the CO2/N2 separation factor and permeability measured as a function of permeation temperature, the maximum separation factor of the PES/10 % MFI-silica zeolite for the pure gas reaches 35 at 25 °C.

Fabrication and characterization of polysulfone/polyimide–zeolite mixed matrix membrane for gas separation

In this study the gas separation performance of polyimide/polysulfone (PI/PSF) mixed matrix membranes filled with zeolite ZSM-5 particles is investigated. The membranes are prepared by solution-casting method and utilized to determine the permeation rates of N 2, O 2, CO 2 and CH 4 through pure polymers as well as composite membranes. The membranes are characterized by SEM, TGA and FTIR. The effects of polymers ratio and weight fraction of zeolite on permeation and selectivity of the gases are discussed. Polymers ratio in the mixed matrix have assumed values of 100% PSF, 70/30 (PSF/PI), 50/50, 30/70 and 100% PI while ZSM-5 loadings are varied between 0 and 20 wt.%. SEM results showed that fabricated membranes have homogeneous structure. With pure polyimide membrane, O 2 permeability increased from 0.69 Barrer for membrane without zeolite up to 0.73 and 0.89 Barrer for membranes with 10% and 20% zeolite, respectively. Within blended matrices, the minimum permeability (maximum selectivity) and the most homogeneous matrix structure were related to the matrix with 50/50 weight percent of two polymers.

Fabrication and characterization of silica modified polyimide–zeolite mixed matrix membranes for gas separation properties

In this study, new monomers having silica groups were synthesized as an intermediate for the preparation of poly(imide siloxane)-zeolite 4A and 13X mixed matrix membranes (MMMs). The effects of membrane preparation steps, zeolite loading, precursor’s composition, and pore size of zeolite on the gas separation performance of these mixed matrix membranes were studied. The new diamine monomer was prepared from 3,5-diaminobenzoic acid (3,5-DABA), 3-aminopropyltrimethoxysilane (3-APTMS), and zeolite 4A and zeolite 13X in N-methyl-2-pyrollidone (NMP) at 180 °C. Poly(imide siloxane)-zeolite 4A and 13X MMMs were synthesized from pyromellitic dianhydride (PMDA) and 4,4-oxydianiline (ODA) in NMP using a two-step thermal imidization. SEM images of the MMMs show the interface between polymer and zeolite phases getting closer when surface modified zeolite is used. The increase in glass transition temperature (Tg) confirms the polymer chain becoming more rigid induced by the presence of zeolite. The experimental results indicated that a higher zeolite loading resulted in a decrease in gas permeability and an increase in gas pair selectivity. In terms of O2 and N2 permeance and ideal selectivity, the separation performances of poly(imide siloxane)-zeolite MMMs were related to the zeolite type and zeolite pore dimension.

Removing thiophenes from n-octane using PDMS–AgY zeolite mixed matrix membranes

PDMS–AgY zeolite mixed matrix membranes were prepared for separation of thiopenes from mixture of n-octane, thiophene and 2-methyl-thiophene. Experimental results show that AgY zeolite incorporation in PDMS membranes leads to a significant increase in total flux. This can mainly be attributed to the Knudsen diffusion of the feed species in the macro- and meso-pores existing in AgY zeolite. Effect of AgY filling on the selectivity is a trade-off between the interaction of AgY zeolite particles and thiophenes and the Knudsen diffusion occurring in the zeolite pores. Only a slight decrease in enrichment factor for both the thiophenes could be found in the mixed matrix membranes. Moreover, the difference between enrichment factors of non-filled and filled membranes become unapparent when the temperature increases, implying that a kinetic barrier in the sorption and desorption process on the surface or within the pores of AgY zeolites might exist. Most experimental points of AgY-filled PDMS membranes locate above the upper bound curve of pure PDMS membranes for separation of n-octane/thiophenes, indicating that higher permeability was gained with little expense of selectivity using PDMS–AgY zeolite mixed matrix membranes.