52 research outputs found

    Adjustable Functionalization of Hyper-Cross-Linked Polymers of Intrinsic Microporosity for Enhanced CO2 Adsorption and Selectivity over N2 and CH4

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    In this paper, we report the design, synthesis, and characterization of a series of hyper-cross-linked polymers of intrinsic microporosity (PIMs), with high CO2 uptake and good CO2/N2 and CO2/CH4 selectivity, which makes them competitive for carbon capture and biogas upgrading. The starting hydrocarbon polymers’ backbones were functionalized with groups such as −NO2, −NH2, and −HSO3, with the aim of tuning their adsorption selectivity toward CO2 over nitrogen and methane. This led to a significant improvement in the performance in the potential separation of these gases. All polymers were characterized via Fourier transform infrared (FTIR) spectroscopy and 13C solid-state NMR to confirm their molecular structures and isothermal gas adsorption to assess their porosity, pore size distribution, and selectivity. The insertion of the functional groups resulted in an overall decrease in the porosity of the starting polymers, which was compensated with an improvement in the final CO2 uptake and selectivity over the chosen gases. The best uptakes were achieved with the sulfonated polymers, which reached up to 298 mg g–1 (6.77 mmol g–1), whereas the best CO2/N2 selectivities were recorded by the aminated polymers, which reached 26.5. Regarding CH4, the most interesting selectivities over CO2 were also obtained with the aminated PIMs, with values up to 8.6. The reason for the improvements was ascribed to a synergetic contribution of porosity, choice of the functional group, and optimal isosteric heat of adsorption of the materials

    Membranes with Intrinsic Micro-Porosity: Structure, Solubility, and Applications

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    Microporous polymer membranes have been widely studied because of their excellent separation performance. Among them, polymers of intrinsic micro-porosity (PIMs) have been regarded as a potential next-generation membrane material for their ultra-permeable characteristics and their solution-processing ability. Therefore, many reviews have been reported on gas separation and monomers for the preparation of PIMs. This review aims to provide an overview of the structure-solubility property. Different structures such as non-network and network macromolecular structure made of different monomers have been reviewed. Then their solubility with different structures and different separation applications such as nanofiltration, pervaporation, and gas/vapor separation are summarized. Lastly, we also provide our perspectives on the challenges and future directions of the microporous polymer membrane for the structure-property relationship, anti-physical aging, and more

    Sep. Purif. Technol.

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    When butanol and water are mixed at a proper ratio, phase separation can occur because of the immiscibility of butanol with water. A highly concentrated aqueous butanol solution in the organic phase can be obtained. Thus, in this study, the phase separation of the permeate was examined during pervaporation (PV) of an acetone-butanol-ethanol-water solution (ABE-water solution) to obtain a high permeate organic concentration. The effects of feed composition and operating temperatures on the phase separation of the permeate obtained during pervaporation of acetone-butanol-water and ethanol-butanol-water solutions were first evaluated with different membranes. Acetone and ethanol both hindered the phase separation of the permeate because of their miscibility with water and butanol. In the separation of the acetone-butanol-water solution, higher temperatures and lower acetone concentrations in the feed solution favored phase separation in the permeate, whereas for the ethanol-butanol-water solution, lower temperatures and lower ethanol concentrations in the feed solution led to relatively facile phase separation in the permeate. Pervaporation of a 1.5 wt% ABE-water solution with different membranes at different temperatures was also performed. When phase separation in the permeate occurred under proper conditions, the ABE concentration in the organic phase reached approximately 68 wt%. (C) 2014 Elsevier B.V. All rights reserved.When butanol and water are mixed at a proper ratio, phase separation can occur because of the immiscibility of butanol with water. A highly concentrated aqueous butanol solution in the organic phase can be obtained. Thus, in this study, the phase separation of the permeate was examined during pervaporation (PV) of an acetone-butanol-ethanol-water solution (ABE-water solution) to obtain a high permeate organic concentration. The effects of feed composition and operating temperatures on the phase separation of the permeate obtained during pervaporation of acetone-butanol-water and ethanol-butanol-water solutions were first evaluated with different membranes. Acetone and ethanol both hindered the phase separation of the permeate because of their miscibility with water and butanol. In the separation of the acetone-butanol-water solution, higher temperatures and lower acetone concentrations in the feed solution favored phase separation in the permeate, whereas for the ethanol-butanol-water solution, lower temperatures and lower ethanol concentrations in the feed solution led to relatively facile phase separation in the permeate. Pervaporation of a 1.5 wt% ABE-water solution with different membranes at different temperatures was also performed. When phase separation in the permeate occurred under proper conditions, the ABE concentration in the organic phase reached approximately 68 wt%. (C) 2014 Elsevier B.V. All rights reserved

    Fabrication of high silicalite-1 content filled PDMS thin composite pervaporation membrane for the separation of ethanol from aqueous solutions

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    Sedimentation of silicalite-1 occurs in the fabrication of thin silicalite-1 filled polydimethylsiloxane (PDMS) hybrid composite membranes if the viscosity of membrane solution is low, which makes this preparation challenging. In this work, a new method that use a platinum catalytic agent to assist the pre-polymerization of PDMS polymer to increase the viscosity of the membrane solution was studied. With this method, supported silicalite-1 filled PDMS hybrid composite membranes were fabricated and applied in the pervaporative separation of a 5 wt% dilute ethanol aqueous solution. The effect of the concentration of platinum catalytic agent on the membrane properties was first investigated using CRM, DSC and extraction experiment. Optimum of viscosity of the composite membrane solution was then conducted and a selective layer of as thin as 5 gm thickness was obtained with a flux of 5.52 kg/m(2)h in combination with a separation factor of 15.5 at 50 degrees C. After that the separation performances of different thick membranes, interfacial adhesion properties of hybrid membranes, comparisons with other reported results and membrane stability were investigated. Results showed homemade silicalite-1-PDMS hybrid composite membrane offers relatively high separation performance, indicating a potential industrial application for the separation of ethanol from aqueous solutions.</p

    Separation of acetone, butanol and ethanol (ABE) from dilute aqueous solutions by silicalite-1/PDMS hybrid pervaporation membranes

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    To study the effects of different factors on the separation of acetone, butanol, and ethanol (ABE) from ABE-water solutions by pervaporation with silicalite-l/polydimethylsiloxane (PDMS) hybrid membranes, the adsorption of ABE in the silicalite-1 in acetone-butanol-water solution and ethanol-butanol-water solution was firstly investigated and then the separation of ABE from binary aqueous solutions at different feed concentrations and temperatures was examined. Experimental results showed that butanol could be preferentially adsorbed on silicalite-1 and the permeability of acetone through the membrane was the highest, followed by butanol and ethanol, which was not consistent with the predictions based on the experimental results of adsorption and membrane swelling measurement. This could be explained by Hansen solubility parameters for the component and polymer interactions (delta(m,c)) and for the organic solvent and water interactions (delta(w,i)). In the separation of ABE-water solution by the silicalite-1/PDMS hybrid pervaporation membranes, acetone and ethanol could promote ABE transport through membrane and block water permeation, and the membrane performance could be significantly affected by vacuum pressure in the permeate side. (C) 2011 Elsevier B.V. All rights reserved
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