Gas permeation characteristics of polymer-zeolite mixed matrix membranes (original) (raw)
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The Effect of Type Zeolite on the Gas Transport Properties of Polyimide-Based Mixed Matrix Membranes
Reaktor, 2008
The permeation rates of O2, N2, CO2 and CH4 has been studied for polyimide-polyethersulfone (PI/PES) blends-zeolite mixed matrix membranes synthesized in our laboratory. The study investigated the effect of zeolite loading and different zeolite type on the gas separation performance of these mixed matrix membranes. Frequency shifts and absorption intensity changes in the FTIR spectra of the PI/PES blends as compared with those of the pure polymers indicate that there is a mixing of polymer blends at the molecular level. Differential scanning calorimetry measurements of pure and PI/PES blends membranes have showed one unique glass transition temperature that supports the miscible character of the PI/PES mixture. The PI/PES-zeolite 4A mixed matrix membrane with 25 wt % zeolite loading produced the highest O2/N2 and CO2/CH4 selectivity of around 7.45 and 46.05, respectively.
Journal of Industrial and Engineering Chemistry
Polymeric membrane technology has received extensive attention in the field of gas separation, recently. However, the tradeoff between permeability and selectivity is one of the biggest problems faced by pure polymer membranes, which greatly limits their further application in the chemical and petrochemical industries. To enhance gas separation performances, recent works have focused on improving polymeric membranes selectivity and permeability by fabricating mixed matrix membranes (MMMs). Inorganic zeolite materials distributed in the organic polymer matrix enhance the separation performance of the membranes well beyond the intrinsic properties of the polymer matrix. This concept combines the advantages of both components: high selectivity of zeolite molecular sieve, and mechanical integrity as well as economical processability of the polymeric materials. In this paper gas permeation mechanism through polymeric and zeolitic membranes, material selection for MMMs and their interacti...
STUDY OF PERMEATION OF GASES THROUGH CERAMIC SUPPORTED POLYMERIC AND ZEOLITE MEMBRANES
2 from various effluent gas mixtures. Membrane operations are recognized as feasible and economical operations over conventional technologies for gas separation due to a higher flexibility to tolerate fluctuations in feed composition and flow rate. In this present work Hydroxy Ethyl Cellulose (HEC) membrane prepared on Silicon carbide (SiC) tube and ZSM-5 membrane casted on α-Al 2 O 3 tube support is used to study the permeation characteristics of various gases. Pour and decanting technique is used to coat HEC membrane on SiC tube whereas seed growth hydrothermal technique is used to prepare ZSM-5 zeolite membrane. Scanning electron microscope (SEM) and X-ray diffraction techniques (XRD) are used to characterize the membranes. Single component permeation experiments are conducted for measurement of permeability coefficients which are essential for understanding and designing the membrane modules. Both the membranes have shown good permeation characteristics for all the gases. Ideal selectivity values are calculated from the pure component permeances.
IRJET, 2022
Mixed matrix membranes (MMM) with moderate filler loading have been shown to improve the transport properties of polymers and their blends for many gas separations. Currently, the main focus of the research is to invent new membranes materials and their combinations for gas separation. PES/PSF (80/20%) blend with dispersed inorganic porous zeolite 4A MMM were fabricated at 10, 20, and 30% ZIF-4A loading For the pure gas permeation, the effect of zeolite 4A loading at 2 bar on permeability (Barrer) and selectivity were investigated. The addition of 10 % zeolite 4A into the polymer blend, increased the permeability about two times for gases O2 and N2, while the ideal selectivity shows a slight increase for pure PES/ PSF blend membrane. For the higher zeolite 4A loadings (≥ 30 %) permeability's were oxygen increasing but Nitrogen started to reduce rapidly due to agglomeration of nanoparticles, but it was found that still, the selectivity improved and increase with the addition of filler into the glassy polymer blend up to 25% and 30% loading
Journal of Membrane Science, 1997
The paper describes the investigation of the effect of three different types of hydrophobic zeolites (ultrastable zeolite type Y, pentasyl type zeolite (ZSM-5), and ALPO-5 type zeolite) on the pervaporation properties of zeolite-filled polydimethylsiloxane membranes. The procedure of obtaining membranes of various thicknesses varying in zeolite content was mastered. The physicochemical properties of the utilized zeolites were investigated and determined. The effect of zeolite type and concentration, as well as the membrane thickness and pervaporation temperature on the membrane permeability and selectivity were investigated. The physicochemical properties of the zeolite used, primarily the degree of hydrophobicity, as well as the sorption capacity for ethanol, the specific pore volume, specific area and mean crystallite size of the zeolite, significantly influence the membrane's pervaporation properties. An increase in the zeolite content results in an increase of both membrane permeability and selectivity, while an increase in the pervaporation temperature results in an increase of the permeability and a decrease of selectivity, as opposed to the effect of membrane thickness.
Ind. Eng. Chem. …, 2002
Silicalite, ZSM5, and mordenite membranes were prepared on alumina and stainless steel porous tubes by several procedures. The N 2 permeation flux was measured before and after exposure to water, n-octane, or n-butane under different conditions (capillary condensation and adsorption). The reduction of permeation flux that takes place in the presence of adsorbable compounds can be related to the quality and separation properties of a given membrane. Also, a good correlation was observed between the separation selectivity and the time required to reach steady state after exposure of the membrane to quasi-saturation conditions. Both measurements can be used as fast and reliable techniques for membrane characterization.
Synthesis, characterization and single gas permeation properties of NaA zeolite membrane
Journal of Membrane Science, 2005
High quality NaA zeolite membrane was synthesized on an ␣-Al 2 O 3 support with the aid of nucleation seeds from a gel synthesis mixture. The influence of synthesis conditions, such as synthesis times, synthesis stages and nucleation seeds, on the formation and permeation properties of the NaA zeolite membranes was investigated. Nucleation seeds played a critical role on the formation of a continuous NaA zeolite membrane on the support surface. The quality of the NaA zeolite membranes were improved by employing the multi-stage synthesis method. The best NaA zeolite membrane was obtained after a three-stage synthesis with the synthesis time of 24 h and with the aid of nucleation seeds. Single gas permeation properties of the NaA zeolite membranes were studied. The permeance of H 2 , O 2 , N 2 and n-C 4 H 10 decreased as the molecular kinetic diameter of the gases increased. At 298 K and under pressure difference of 0.10 MPa, the permselectivity of H 2 /N 2 , H 2 /n-C 4 H 10 and O 2 /N 2 were 20.1, 106 and 2.61, respectively, which were much higher than those of the corresponding Knudsen diffusion ratios of 3.74, 5.39 and 0.96. With increasing temperature, the gas permeance increased and the permselectivity of H 2 /N 2 , H 2 /n-C 4 H 10 and O 2 /N 2 slightly decreased. All these properties indicated that the gases mainly permeated through the channels of NaA zeolite and the gas permeation was predominantly controlled by the molecular sieving effect of NaA zeolite membrane. However, the permeation of n-C 4 H 10 indicated that the NaA zeolite membranes had certain defects with diameters larger than the pore size of NaA zeolite.
Journal of the American Ceramic Society, 2013
Zeolite NaA membranes were prepared hydrothermally by secondary crystallization process at different temperatures (55°C-75°C) on porous a-alumina-based support tubes (inner side) precoated with poly(ethyleneimine) (PEI) buffer layer and NaA seed particles. The NaA seed crystals synthesized at 65°C /2 h in the size range 100-200 nm having BET surface area of 71.57 m 2 g À1 were used for secondary crystallization of the membranes. The secondary crystallization at 65°C for (4 + 4) h (double-stage) showed highly dense NaA grains in the microstructure of the membrane with a thickness of 5 lm. It rendered the permeance values of 50.6 3 10 À8 , 2.47 3 10 À8 , and 0.55 3 10 À8 molm À2 s À1 Pa À1 for H 2 , N 2 , and CO 2 , respectively, with their permselectivity of 20.48 (H 2 / N 2 ), 92 (H 2 /CO 2 ), and 4.49 (N 2 /CO 2 ). A tentative mechanism was illustrated for the interaction of PEI with the support substrate and NaA seed crystals.
Adsorption and diffusion properties of zeolite membranes by transient permeation
Desalination, 2002
Adsorption isotherms and diffusion coefficients for light gases and butane isomers were measured for the transport pathways involved in gas permeation through H-ZSM-5 membranes by a transient permeation technique. The permeate responses to step changes in the feed were measured, and the transport was modeled as Maxwell-Stefan diffusion with single-site Langmuir adsorption in the zeolite. Isotherms measured for N 2 , CO 2 , and CH 4 at 295 K were nearly identical to those measured by calorimetry on H-ZSM-5 powders. Isotherms for butane isomers were also similar to isotherms for MFI powders and heats of adsorption and diffusion activation energies were in the ranges reported in the literature. Maxwell-Stefan diffusion coefficients for all gases studied increased slightly with feed partial pressure and were similar to those measured by other macroscopic methods for zeolite membranes and crystals. Effective membrane thicknesses were also determined non-destructively for tubular zeolite membranes by the transient permeation technique.