Show/Hide Menu
Hide/Show Apps
Logout
Türkçe
Türkçe
Search
Search
Login
Login
OpenMETU
OpenMETU
About
About
Open Science Policy
Open Science Policy
Open Access Guideline
Open Access Guideline
Postgraduate Thesis Guideline
Postgraduate Thesis Guideline
Communities & Collections
Communities & Collections
Help
Help
Frequently Asked Questions
Frequently Asked Questions
Guides
Guides
Thesis submission
Thesis submission
MS without thesis term project submission
MS without thesis term project submission
Publication submission with DOI
Publication submission with DOI
Publication submission
Publication submission
Supporting Information
Supporting Information
General Information
General Information
Copyright, Embargo and License
Copyright, Embargo and License
Contact us
Contact us
Syntheses of self-supported tubular zeolite a membranes
Download
index.pdf
Date
2008
Author
Gücüyener, Canan
Metadata
Show full item record
Item Usage Stats
198
views
200
downloads
Cite This
Zeolites are microporous hydrated aluminosilicate crystals containing alkali and/or alkali earth metal cations in their frameworks. Due to their molecular size pores, they can separate molecules according to their size and shape. Zeolites are mostly used in ion exchange, adsorption processes and catalytic applications. The hydrophilic/hydrophobic character of zeolites also makes them favorable materials for adsorption based separations. Recently the potential of zeolite/ceramic composite membranes have been shown in the separation of liquid and gas mixtures. Self-supported zeolite membranes with asymmetric structure can be an alternative to the composite zeolite membranes. Because asymmetric structure may eliminate the problems originated from the differences in thermal expansion coefficients of zeolites and ceramics. In this study tubular zeolite A membranes were prepared on binderless zeolite A supports. The supports were perepared by hydrothermal conversion of amorphous aluminosilicate tubes into zeolite A. The amorphous aluminosilicate powder, which was obtained by filtering the homogenous hydrogel with a composition of 2.5Na2O:1Al2O3:1.7SiO2:150H2O, was mixed with an organic binder (HEC-Hydroxyethyl Cellulose) and water to obtain the paste. The paste was then extruded through a home-made extruder into bars and tubes. These extrudates were dried at room temperature for 24 hours, calcined at 600oC for 2 hours to remove organic binder and finally synthesized at 80oC for 72 hours in hydrothermal conditions to convert amorphous aluminosilicate to zeolite. The effect of composition of the synthesis solution on the crystallinity and morphology of zeolite A tubes and bars were investigated. The crystallization field of zeolite A bars has been established and shown on a ternary phase diagram. Tubes were mechanically stable, typically had a crystallinity over 90% and a macroporosity of 35%. The tubes were composed of highly intergrown crystals of zeolite A. The average particle size was 3.5 m. The asymmetric membranes were synthesized by growing zeolite A films on binderless zeolite A supports with a geometry of disk, bar and tube. Continuous zeolite A films can only be obtained when the supports were saturated with water prior to synthesis. The film thicknesses were approximately 5 m on disks and approximately 10 m on tubes. A method was proposed to prepare self-supported tubular zeolite A membranes in this study.
Subject Keywords
Chemical engineering.
,
Inorganic chemistry.
URI
http://etd.lib.metu.edu.tr/upload/12609879/index.pdf
https://hdl.handle.net/11511/18200
Collections
Graduate School of Natural and Applied Sciences, Thesis
Suggestions
OpenMETU
Core
Dissolution of colemanite and crystallization of gypsum during boric acid production in a batch reactor
Erdoğdu, Anıl; Eroğlu, İnci; Department of Chemical Engineering (2004)
One of the most commonly used boron compounds, boric acid, is produced by dissolving colemanite (2CaO₉3B2O3₉5H2O) in aqueous sulfuric acid whereby gypsum (CaSO4₉2H2O) is formed as a byproduct and must be separated from the main product. This process consists of two steps, dissolution of colemanite and formation of gypsum. The amount of boric acid formed depends on the first step, dissolution of colemanite. In the latter step, gypsum crystals are formed and stay in the reaction mixture to grow up to a size l...
Production of boron nitride
Özkol, Engin; Özbelge, Hilmi Önder; Department of Chemical Engineering (2008)
Boron nitride is found mainly in two crystal structures; in hexagonal structure (h-BN) which is very much like graphite and in cubic structure (c-BN) with properties very close to those of diamond. h-BN is a natural lubricant due to its layered structure. It is generally used in sliding parts of the moving elements such as rotating element beds in turbine shafts. Since c-BN is the hardest known material after diamond it is used in making hard metal covers. In addition to its possible microelectronics applic...
Characterization of zeolite membranes by gas permeation
Soydaş, Belma; Kalıpçılar, Halil; Department of Chemical Engineering (2009)
Zeolite membranes are attractive materials to separate gas and liquid mixtures. MFI is a widely studied zeolite type due to its ease of preparation and comparable pore size with the molecular size of many substances. In this study MFI type membranes were synthesized over porous α-Al2O3 supports and characterized with XRD, SEM and gas permeation measurements. In the first part of this study the effect of soda concentration of the synthesis solution on the membrane morphology and crystal orientation was inves...
Synthesis and Characterization of Aluminum Containing Silica Aerogel Catalysts for Degradation of PLA
Sivri, Seda; Dilek Hacıhabiboğlu, Çerağ; Sezgi, Naime Aslı (Walter de Gruyter GmbH, 2019-05-01)
Aluminum loaded silica aerogel based catalysts were synthesized by impregnation of aluminum into silica aerogel produced using sol-gel method in different aluminum loadings (2.5-15 wt%) to investigate their performances in degradation of polylactic acid (PLA).
Dynamic Behavior of continuous flow stirred slurry reactors in boric acid production
Yücel Çakal, Gaye Ö; Eroğlu, İnci; Department of Chemical Engineering (2004)
One of the most important boron minerals, colemanite is reacted with sulfuric acid to produce boric acid. During this reaction, gypsum (calcium sulfate dihydrate) is formed as a byproduct. In this study, the boric acid production was handled both in a batch and four continuously stirred slurry reactors (4-CFSSR̕s) in series system. In this reaction system there are at least three phases, one liquid and two solid phases (colemanite and gypsum). In a batch reactor all the phases have the same operating time (...
Citation Formats
IEEE
ACM
APA
CHICAGO
MLA
BibTeX
C. Gücüyener, “Syntheses of self-supported tubular zeolite a membranes,” M.S. - Master of Science, Middle East Technical University, 2008.