Title:
Engineering nanoporous materials for application in gas separation membranes

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dc.contributor.advisor Jones, Christopher W.
dc.contributor.advisor Nair, Sankar
dc.contributor.author Bae, Tae-Hyun en_US
dc.contributor.committeeMember Koros, William
dc.contributor.committeeMember Meredith, Carson
dc.contributor.committeeMember Wang, Zhong Lin
dc.contributor.department Chemical Engineering en_US
dc.date.accessioned 2012-02-17T19:12:18Z
dc.date.available 2012-02-17T19:12:18Z
dc.date.issued 2010-08-11 en_US
dc.description.abstract The main theme of this dissertation is to engineer nanoporous materials and nanostructured surfaces for applications in gas separation membranes. Tunable methods have been developed to create inorganic hydroxide nanostructures on zeolite surfaces, and used to control the inorganic/polymer interfacial morphology in zeolite/polymer composite membranes. The study of the structure-property relationships in this material system showed that appropriate tuning of the surface modification methods leads to quite promising structural and permeation properties of the membranes made with the modified zeolites. First, a facile solvothermal deposition process was developed to prepare roughened inorganic nanostructures on zeolite pure silica MFI crystal surfaces. The functionalized zeolite crystals resulted in high-quality ̒mixed matrix̕ membranes, wherein the zeolite crystals were well-adhered to the polymeric matrix. Substantially enhanced gas separation characteristics were observed in mixed matrix membranes containing solvothermally modified MFI crystals. Gas permeation measurements on membranes containing nonporous uncalcined MFI revealed that the performance enhancements were due to significantly enhanced MFI-polymer adhesion and distribution of the MFI crystals. Solvothermal deposition of inorganic nanostructures was successfully applied to aluminosilicate LTA surfaces. Solvothermal treatment of LTA was tuned to deposit smaller/finer Mg(OH)₂ nanostructures, resulting in a more highly roughened zeolite surface. Characterization of particles and mixed matrix membranes revealed that the solvothermally surface-treated LTA particles were promising for application in mixed matrix membranes. Zeolite LTA materials with highly roughened surfaces were also successfully prepared by a new method: the ion-exchange-induced growth of Mg(OH)₂ nanostructures using the zeolite as the source of the Mg²⁺ ions. The size/shape of the inorganic nanostructures was tuned by adjusting several parameters such as the pH of the reagent solution and the amount of magnesium in the substrates and systematic modification of reaction conditions allowed generation of a good candidate for application in mixed matrix membranes. Zeolite/polymer adhesion properties in mixed matrix membranes were improved after the surface treatment compared to the untreated bare LTA. Surface modified zeolite 5A/6FDA-DAM mixed matrix membranes showed significant enhancement in CO₂ permeability with slight increases in CO₂/CH₄ selectivity as compared to the pure polymer membrane. The CO₂/CH₄ selectivity of the membrane containing surface treated zeolite 5A was much higher than that of membrane with untreated zeolite 5A. In addition, the use of metal organic framework (MOF) materials has been explored in mixed matrix membrane applications. ZIF-90 crystals with submicron and 2-μm sizes were successfully synthesized by a nonsolvent induced crystallization technique. Structural investigation revealed that the ZIF-90 particles synthesized by this method had high crystallinity, microporosity and thermal stability. The ZIF-90 particles showed good adhesion with polymers in mixed matrix membranes without any compatibilization. A significant increase in CO₂ permeability was observed without sacrificing CO₂/CH₄ selectivity when Ultem® and Matrimd® were used as the polymer matrix. In contrast, mixed matrix membranes with the highly permeable polymer 6FDA-DAM showed substantial enhancement in both permeability and selectivity, as the transport properties of the two phases were more closely matched. en_US
dc.description.degree PhD en_US
dc.identifier.uri http://hdl.handle.net/1853/42712
dc.publisher Georgia Institute of Technology en_US
dc.subject Gas separation en_US
dc.subject Membrane en_US
dc.subject Zeolite en_US
dc.subject Metal organic framework en_US
dc.subject Molecular sieve en_US
dc.subject Polymer composite en_US
dc.subject.lcsh Gas separation membranes en_US
dc.subject.lcsh Membranes (Technology) en_US
dc.subject.lcsh Gases Separation en_US
dc.subject.lcsh Membranes (Technology) en_US
dc.subject.lcsh Adsorption en_US
dc.title Engineering nanoporous materials for application in gas separation membranes en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Jones, Christopher W.
local.contributor.advisor Nair, Sankar
local.contributor.corporatename School of Chemical and Biomolecular Engineering
local.contributor.corporatename College of Engineering
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relation.isAdvisorOfPublication f45fbda5-be0c-4299-bd7b-8d035ad1b61f
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relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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