Effect of seeding on the properties of mfi type zeolite membranes

Dinçer, Eser
The effect of seeding on the properties of alumina supported MFI membranes was investigated in this study. Membranes were synthesized from clear solutions with a molar batch composition of TPAOH:9.80SiO2:0.025NaOH:0.019Al2O3: 602.27H2O:39.16C2H5OH on bare and seeded alumina supports at 130oC in autoclaves. The amount of seed on the support surface was changed between 0.6 mg/cm2 and 6.9 mg/cm2 by vacuum seeding method, which provided uniform and closely packed seed layers. Membranes were characterized by XRD and SEM, and by measuring single gas permeances of N2, SF6, n-C4H10 and i-C4H10. The quality of membranes was evaluated on the basis of N2/SF6 ideal selectivity. Membranes, which showed N2/SF6 ideal selectivity higher than 40, were considered to be good quality, comprising few defects. Good quality membranes were also used to separate butane isomers. Membranes synthesized on seeded supports had compact and uniform MFI layer if the seed amount is less than 1.0 mg/cm2 on the support surface. Membranes that were synthesized on the supports coated with higher amount of seed crystals showed an asymmetric structure with a dense and uniform MFI layer at the top, the support at the bottom and a seed layer between. Half of the membranes synthesized on seeded supports had N2/SF6 ideal selectivity higher than 40. These membranes exhibited n-C4H10/i-C4H10 separation selectivities between 5 and 27 and 8 and 21 at room temperature and at 200oC, respectively. High ideal and separation selectivities showed that membranes did not include non-zeolitic pores. Membranes synthesized on bare support had non-uniform MFI layer. Those membranes showed N2/SF6 ideal selectivities below Knudsen selectivity, indicating the existence of large non-zeolitic pores in the MFI layer.


FOLKES, MJ; KALAY, G (Elsevier BV, 1993-01-01)
The effects of various thermal treatments on the properties of both PEEK and APC2 have been systematically studied. X-ray diffraction data, together with dynamic mechanical measurements, indicate that the T(g) values for both materials are considerably higher than those generally reported. Also, the tan delta values for quenched APC2 specimens are considerably higher than for slowly cooled materials. Microstructural observations show that this is likely to be due to poor fibre/matrix adhesion, in the case o...
Synthesis of mfı type zeolite membranes in a continuous system
Çulfaz, Pınar Zeynep; Kalıpçılar, Halil; Department of Chemical Engineering (2005)
MFI type zeolites, are the most widely studied zeolites for membrane separations. Conventionally, zeolite membranes are prepared in batch systems by hydrothermal synthesis in autoclaves. This method has several disadvantages for use in industrial scale for the synthesis of membranes with large areas and complex geometries that are commonly used in membrane modules. The objective of this study is to prepare MFI type zeolite membranes on tubular alumina supports in a continuous system where the synthesis solu...
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Kayed, TS; Ozkan, H; Hasanlı, Nızamı (IOP Publishing, 2001-09-01)
The effects of lithium doping on the formation and properties of the T1-based superconductors have been studied. Lithium atoms up to around 3 mol.% have been added to the oxides of nominal composition Tl1.8Ba2Ca2.2Cu3Ox, and the usual solid-state reaction method has been applied. Lithium additions in the range 0.23-0.29 mol.% increase the fraction of the Tl-2223 phase and significantly improve the critical temperature of the samples. Higher amounts of lithium additions diminish the Tl-2223 phase, reduce the...
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ÇAMURLU, HASAN ERDEM; SEVİNÇ, NACİ; Topkaya, Yavuz Ali (Elsevier BV, 2008-01-01)
Effect of CaCO3 on formation of hexagonal boron nitride (h-BN) was investigated by holding CaCO3 free and CaCO3 added activated carbon-boric oxide mixtures under nitrogen atmosphere at 1500 degrees C for 30-120 min. Amount of CaCO3 addition was varied in the range of 0-50 wt.% of the initial mixture. Products were characterized by powder X-ray diffractometry, FT-IR analysis, quantitative chemical analysis, scanning electron microscopy and BET specific surface area analysis. It was observed that calcium carb...
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MEYVA, YELDA; Kaynak, Cevdet (Informa UK Limited, 2016-01-01)
The aim of this study was to investigate influences of three different ethylene copolymers on the toughness and other properties of very brittle biopolymer PLA (polylactide). For this aim, PLA was melt blended by twin-screw extruder with various amounts of ethylene vinyl acetate (EVA), ethylene-methyl-acrylate (EMA) and ethylene-n-butyl acrylate-glycidyl-methacrylate (EBA-GMA). SEM and DSC analyses indicated that these ethylene copolymers were thermodynamically immiscible with phase separation in the form o...
Citation Formats
E. Dinçer, “Effect of seeding on the properties of mfi type zeolite membranes,” M.S. - Master of Science, Middle East Technical University, 2005.