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Effects of thermal crosslinking treatment on gas separation performance and stability of polymeric membranes
Martin-Gil, V. ; Hrabánek, Pavel ; Sysel, P. ; Fíla, V.
In this work, (4,4’-Hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,4,6- trimethyl-1,3-diaminobenzene (DAM) and 3,5-diaminobenzoic acid (DABA) were used to synthesize copolyimides with different ratios of DAM:DABA (2:1 and 9:1) as well as polyimide 6FDA-DAM in order to check the influence of acidic group from DABA in the membrane formation process as well as in the crosslinking treatment. The main aim of crosslinking treatment is to improve the CO 2 induced plasticization resistance of the membrane. Copolyimides were synthesized using two steps reaction: (i) synthesis of polyamic acid (PAA) and (ii) thermal imidization in solution. The obtained crosslinked membranes presented solvent resistance due to the transesterification of the polymer. Furthermore, it could be observed that the crosslinked membranes showed higher permeabilities for small gases (He and H 2 ) and for bigger gases (CO 2 and CH 4 ) permeabilities decreased slightly. It can be due to the densification of the membrane during the thermal treatment. However, this treatment presents highly promising results for H 2 recovery in syngas production or extraction of hydrogen from petroleum naphtha cracking streams
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Development of silane modified TS-1 nanoparticles as fillers for Mixed Matrix Membranes (MMM’s)
Martin-Gil, V. ; Lhotka, M. ; Hrabánek, Pavel ; Fíla, V.
In this work, Titanium Silicalite 1 (TS-1) was synthesized using different crystallization temperature (Tc = 180 °C, 160°C, 140°C), aging time (t aging = 1, 2, 3 and 7 days) and aging temperature (T aging = T room , 40 °C, 80°C) in order to get suitable nanoparticle size and good distribution of particle size for using them as a filler in MMMs. The TS-1 particles with different Si/Ti ratios (Si/Ti = 25 and 100) were functionalized using different amino silane coupling agents: 3-aminopropyltriethoxysilane (APTES), 3- aminopropyltrimethoxysilane (APTMS) and 3-aminopropylmethyldiethoxysilane (APMDES). Moreover, a new kind of silane coupling agents: 3- glycidoxypropyltriethoxysilane (GPTES), 3-glycidoxypropyltrimethoxysilane (GPTMS) and 3-glycidoxymethyldiethoxysilane (GPMDES) were also used. Tetrahydrofuran (THF), with a high dielectric constant (7.6), was used as solvent in order to control the surface modification and avoid pore blockage. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), as well as carbon dioxide methane and nitrogen adsorption measurements. The obtained results showed that aging temperature at long aging times have the main effect on the morphology of the particles meanwhile crystallization temperature influences gas adsorption properties. T aging higher than T room showed a great influence on the particle size at t aging = 7 days; shorter t aging did not show an observable influence on the particle size. Crystallization temperature influences the adsorption properties; at lower crystallization temperature, higher quantity of CO 2 adsorbed and lower quantity of CH 4 adsorbed. At last, suitable TS-1 filler with good size distribution and particle size about 200nm was obtained using Si/Ti = 100 and Si/Ti = 25, T c = 140 °C, T aging = 40 °C and t aging = 7 days.
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