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1.
Haldoupis, Emmanuel.
Mulitscale modeling and screening of nanoporous materials and membranes for separations.
Degree: PhD, Chemical and Biomolecular Engineering, 2013, Georgia Tech
URL: http://hdl.handle.net/1853/47669 
► The very large number of distinct structures that are known for metal-organic frameworks (MOFs) and zeolites presents both an opportunity and a challenge for identifying…
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▼ The very large number of distinct structures that are known for metal-organic frameworks (MOFs) and zeolites presents both an opportunity and a challenge for identifying materials with useful properties for targeted separations. In this thesis we propose a three-stage computational methodology for addressing this issue and comprehensively screening all available nanoporous materials. We introduce efficient pore size calculations as a way of discarding large number of materials, which are unsuitable for a specific separation. Materials identified as having desired geometric characteristics can be further analyzed for their infinite dilution adsorption and diffusion properties by calculating the Henry's constants and activation energy barriers for diffusion. This enables us to calculate membrane selectivity in an unprecedented scale and use these values to generate a small set of materials for which the membrane selectivity can be calculated in detail and at finite loading using well-established computational tools. We display the results of using these methods for >500 MOFs and >160 silica zeolites for spherical adsorbates at first and for small linear molecules such as CO₂ later on. In addition we also demonstrate the size of the group of materials this procedure can be applied to, by performing these calculations, for simple adsorbate molecules, for an existing library of >250,000 hypothetical silica zeolites. Finally, efficient methods are introduced for assessing the role of framework flexibility on molecular diffusion in MOFs that do not require defining a classical forcefield for the MOF. These methods combine ab initio MD of the MOF with classical transition state theory and molecular dynamics simulations of the diffusing molecules. The effects of flexibility are shown to be large for CH₄, but not for CO₂ and other small spherical adsorbates, in ZIF-8.
Advisors/Committee Members: Dr. David S. Sholl (Committee Chair), Dr. Christopher W. Jones (Committee Member), Dr. Krista S. Walton (Committee Member), Dr. Peter J. Hesketh (Committee Member), Dr. Sankar Nair (Committee Member).
Subjects/Keywords: Molecular simulations; Separations; Zeolites; Metal-organic frameworks; Nanoporous; Nanostructured materials; Membranes (Technology); Separation (Technology)
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APA (6th Edition):
Haldoupis, E. (2013). Mulitscale modeling and screening of nanoporous materials and membranes for separations. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/47669
Chicago Manual of Style (16th Edition):
Haldoupis, Emmanuel. “Mulitscale modeling and screening of nanoporous materials and membranes for separations.” 2013. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/47669.
MLA Handbook (7th Edition):
Haldoupis, Emmanuel. “Mulitscale modeling and screening of nanoporous materials and membranes for separations.” 2013. Web. 17 Apr 2021.
Vancouver:
Haldoupis E. Mulitscale modeling and screening of nanoporous materials and membranes for separations. [Internet] [Doctoral dissertation]. Georgia Tech; 2013. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/47669.
Council of Science Editors:
Haldoupis E. Mulitscale modeling and screening of nanoporous materials and membranes for separations. [Doctoral Dissertation]. Georgia Tech; 2013. Available from: http://hdl.handle.net/1853/47669
Georgia Tech
2.
Hillock, Alexis Maureen Wrenn.
Crosslinkable Polyimide Mixed Matrix Membranes for Natural Gas Purification.
Degree: PhD, Chemical Engineering, 2005, Georgia Tech
URL: http://hdl.handle.net/1853/13933
► Crosslinkable mixed matrix membranes represent an attractive technology that promises both outstanding separation properties and swelling resistance for the purification of natural gas. This approach…
(more)
▼ Crosslinkable mixed matrix membranes represent an attractive technology that promises both outstanding separation properties and swelling resistance for the purification of natural gas. This approach relies upon dispersal of a CO2/CH4 size-discriminating zeolite in a crosslinkable polymer, which is resistant to CO2 swelling when crosslinked. The resulting membrane has the potential to separate CO2 from CH4 more effectively than traditional pure polymer membranes, while also providing needed membrane stability in the presence of aggressive CO2-contaminated natural gas streams. Control studies are conducted using the pure crosslinkable polymer to observe the separation properties and swelling resistance. Initial crosslinkable mixed matrix membrane experiments are then performed and result in an increase in membrane productivity, instead of the expected increase in selectivity. Traditionally, this is caused by material incompatibility at the polymer/zeolite interface, so the crosslinkable mixed matrix membranes are characterized to examine this issue. During the material characterization, a new non-ideal transport phenomenon is discovered in the zeolite phase. A model is developed to better understand the transport and predict subsequent experimental results. Once the independent materials are proven to be viable, crosslinkable mixed matrix membranes that show enhancements in both efficiency and productivity and exhibit stability in the presence of aggressive CO2 feeds are created.
Advisors/Committee Members: Dr. William J. Koros (Committee Chair), Dr. Christopher W. Jones (Committee Member), Dr. Haskell W. Beckham (Committee Member), Dr. Ronald W. Rousseau (Committee Member), Dr. Stephen J. Miller (Committee Member).
Subjects/Keywords: Crosslinked polyimide; Gas separation; Natural gas purification; Zeolite mesoporosity; Mixed matrix
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APA (6th Edition):
Hillock, A. M. W. (2005). Crosslinkable Polyimide Mixed Matrix Membranes for Natural Gas Purification. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/13933
Chicago Manual of Style (16th Edition):
Hillock, Alexis Maureen Wrenn. “Crosslinkable Polyimide Mixed Matrix Membranes for Natural Gas Purification.” 2005. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/13933.
MLA Handbook (7th Edition):
Hillock, Alexis Maureen Wrenn. “Crosslinkable Polyimide Mixed Matrix Membranes for Natural Gas Purification.” 2005. Web. 17 Apr 2021.
Vancouver:
Hillock AMW. Crosslinkable Polyimide Mixed Matrix Membranes for Natural Gas Purification. [Internet] [Doctoral dissertation]. Georgia Tech; 2005. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/13933.
Council of Science Editors:
Hillock AMW. Crosslinkable Polyimide Mixed Matrix Membranes for Natural Gas Purification. [Doctoral Dissertation]. Georgia Tech; 2005. Available from: http://hdl.handle.net/1853/13933
Georgia Tech
3.
Nayak, Satish Prakash.
Design, Synthesis and Characterization of Multiresponsive Microgels.
Degree: PhD, Chemistry and Biochemistry, 2005, Georgia Tech
URL: http://hdl.handle.net/1853/6845
► This thesis is geared towards using hydrogel nanoparticles in various biotechnological applications. The polymer that was used in making these nanoparticles was poly(N-isopropylacrylamide), which is…
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▼ This thesis is geared towards using hydrogel nanoparticles in various biotechnological applications. The polymer that was used in making these nanoparticles was poly(N-isopropylacrylamide), which is a thermoresponsive polymer. These particles were used in making fast responsive polymer films, which can be used in optics. It was observed that the rate of deswelling increased as the concentration of the nanoparticles in the film was increased. These particles were also used in making photoresponsive materials. In this case a photoresponsive dye (malachite green) was conjugated to these nanoparticles and in presence of light of appropriate wavelength the particles undergo a phase transition. A core/shell construct was synthesized where the core was composed of degradable cross-links and the shell of composed of non-degradable cross-links. The degradable cross-linker had vicinal diols, which can be cleaved by sodium periodate. Hence after degrading the core, hollow particles were obtained. Zwitterionic particles were made by incorporating a cationic and anionic comonomer. These microgels go from a positively charged state to zwitterionic to negatively charged state on increasing the pH. One of the important potential applications for these microgels is drug delivery. Microgels were used for targeting cancer cells. Folic acid was used as the targeting ligand. The microgels were conjugated with folic acid and were able to target cells that overexpress folate receptors. In one other application core/shell microgels were made which exhibit pore-size dependent permeation of proteins.
Advisors/Committee Members: Dr. L. Andrew Lyon (Committee Chair), Dr. Christopher W. Jones (Committee Member), Dr. Jiri Janata (Committee Member), Dr. Marcus Weck (Committee Member), Dr. Nicholas V. Hud (Committee Member).
Subjects/Keywords: pNIPAm; Core/Shell; Nanoparticles; Hydrogels; Polymers; Thin films; Polymers Thermal properties; Polymers Optical properties; Nanoparticles Synthesis; Colloids
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APA (6th Edition):
Nayak, S. P. (2005). Design, Synthesis and Characterization of Multiresponsive Microgels. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/6845
Chicago Manual of Style (16th Edition):
Nayak, Satish Prakash. “Design, Synthesis and Characterization of Multiresponsive Microgels.” 2005. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/6845.
MLA Handbook (7th Edition):
Nayak, Satish Prakash. “Design, Synthesis and Characterization of Multiresponsive Microgels.” 2005. Web. 17 Apr 2021.
Vancouver:
Nayak SP. Design, Synthesis and Characterization of Multiresponsive Microgels. [Internet] [Doctoral dissertation]. Georgia Tech; 2005. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/6845.
Council of Science Editors:
Nayak SP. Design, Synthesis and Characterization of Multiresponsive Microgels. [Doctoral Dissertation]. Georgia Tech; 2005. Available from: http://hdl.handle.net/1853/6845
4.
Omole, Imona C.
Crosslinked polyimide hollow fiber membranes for aggressive natural gas feed streams.
Degree: PhD, Chemical Engineering, 2008, Georgia Tech
URL: http://hdl.handle.net/1853/26591
► Natural gas is one of the fastest growing primary energy sources in the world today. The increasing world demand for energy requires increased production of…
(more)
▼ Natural gas is one of the fastest growing primary energy sources in the world today. The increasing world demand for energy requires increased production of high quality natural gas. For the natural gas to be fed into the mainline gas transportation system, it must meet the pipe-line quality standards. Natural gas produced at the wellhead is usually "sub-quality" and contains various impurities such as CO2, H2S, and higher hydrocarbons, which must be removed to meet specifications.
Carbon dioxide is usually the most abundant impurity in natural gas feeds and high CO2 partial pressures in the feed can lead to plasticization, which causes loss of some methane product and may ultimately render the membrane ineffective. Moreover, the presence of highly sorbing higher hydrocarbons in the feed can further reduce membrane performance.
Covalent crosslinking has been shown to increase plasticization resistance in dense films by suppressing the degree of swelling and segmental chain mobility in the polymer, thereby preserving the selectivity of the membrane. This research focuses on extending the dense film success to asymmetric hollow fibers.
In this work, the effect of high pressure CO2 (up to 400 psia CO2 partial pressure) on CO2/CH4 mixed gas separation performance was investigated on defect-free the hollow fiber membrane at different degrees of crosslinking. All the crosslinked fibers were shown to exhibit good resistance to selectivity losses from CO2 induced plasticization, significantly more than the uncrosslinked fibers. Robust resistance of the hollow fiber membranes in the presence of toluene (a highly sorbing contaminant) was also demonstrated as the membranes showed no plasticization. Antiplasticization was found to occur in the presence of toluene feeds with the crosslinkable fibers used in this work.
Advisors/Committee Members: Dr. William J. Koros (Committee Chair), Dr. Amyn Teja (Committee Member), Dr. Christopher W. Jones (Committee Member), Dr. Haskell W. Beckham (Committee Member), Dr. Stephen J. Miller (Committee Member).
Subjects/Keywords: Membrane; Carbon dioxide; Natural gas; Hollow fiber; Polyimide; Gas separation; Gas separation membranes; High pressure (Technology); Natural gas; Crosslinked polymers
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APA (6th Edition):
Omole, I. C. (2008). Crosslinked polyimide hollow fiber membranes for aggressive natural gas feed streams. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26591
Chicago Manual of Style (16th Edition):
Omole, Imona C. “Crosslinked polyimide hollow fiber membranes for aggressive natural gas feed streams.” 2008. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/26591.
MLA Handbook (7th Edition):
Omole, Imona C. “Crosslinked polyimide hollow fiber membranes for aggressive natural gas feed streams.” 2008. Web. 17 Apr 2021.
Vancouver:
Omole IC. Crosslinked polyimide hollow fiber membranes for aggressive natural gas feed streams. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/26591.
Council of Science Editors:
Omole IC. Crosslinked polyimide hollow fiber membranes for aggressive natural gas feed streams. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/26591
Georgia Tech
5.
Richardson, John Michael.
Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons.
Degree: PhD, Chemical and Biomolecular Engineering, 2008, Georgia Tech
URL: http://hdl.handle.net/1853/22704
► This work focuses on understanding the heterogeneous/homogeneous nature of the catalytic species for a variety of immobilized metal precatalysts used for C-C coupling reactions. These…
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▼ This work focuses on understanding the heterogeneous/homogeneous nature of the catalytic species for a variety of immobilized metal precatalysts used for C-C coupling reactions. These precatalysts include: (i) tethered organometallic palladium pincer complexes, (ii) an encapsulated small molecule palladium complex in a polymer matrix, (iii) mercapto-modified mesoporous silica metalated with palladium acetate, and (iv) amino-functionalized mesoporous silicas metalated with Ni(II). As part of this investigation, the use of metal scavengers as selective poisons of homogeneous catalysis is introduced and investigated as a test for distinguishing heterogeneous from homogeneous catalysis. The premise of this test is that insoluble materials functionalized with metal binding sites can be used to selectively remove soluble metal, but will not interfere with catalysis from immobilized metal. In this way the test can definitely distinguish between surface and solution catalysis of immobilized metal precatalysts.
This work investigates three different C-C coupling reactions catalyzed by the immobilized metal precatalysts mentioned above. These reactions include the Heck, Suzuki, and Kumada reactions. In all cases it is found that catalysis is solely from leached metal. Three different metal scavenging materials are presented as selective poisons that can be used to determine solution vs. surface catalysis. These selective poisons include poly(vinylpyridine), QuadrapureTM TU, and thiol-functionalized mesoporous silica. The results are contrasted against the current understanding of this field of research and subtleties of tests for distinguishing homogeneous from heterogeneous catalysis are presented and discussed.
Advisors/Committee Members: Dr. Christopher W. Jones (Committee Chair), Dr. E. Kent Barefield (Committee Member), Dr. Marcus Weck (Committee Member), Dr. Pradeep Agrawal (Committee Member), Dr. Rachel Chen (Committee Member).
Subjects/Keywords: Palladium catalysis; Cross coupling reaction; Heterogeneous vs. homogeneous; Selective poisoning; Palladium catalysts; Heterogeneous catalysis; Catalysis; Catalyst poisoning
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APA (6th Edition):
Richardson, J. M. (2008). Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/22704
Chicago Manual of Style (16th Edition):
Richardson, John Michael. “Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons.” 2008. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/22704.
MLA Handbook (7th Edition):
Richardson, John Michael. “Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons.” 2008. Web. 17 Apr 2021.
Vancouver:
Richardson JM. Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/22704.
Council of Science Editors:
Richardson JM. Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/22704
Georgia Tech
6.
Valenzuela, Mariefel Bayta.
Batch Aqueous-phase Reforming of Lignocellulosic Biomass for Hydrogen Production.
Degree: MS, Chemical Engineering, 2006, Georgia Tech
URL: http://hdl.handle.net/1853/11624
► Aqueous-phase reforming (APR) is reported for the first time for the production of H2 from actual biomass. The experiments are carried out in batch using…
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▼ Aqueous-phase reforming (APR) is reported for the first time for the production of H2 from actual biomass. The experiments are carried out in batch using a 100mL Parr microreactor heated to 225C. In this one-pot, two-step process, acid hydrolysis is used to break down the polymeric constituents of biomass to smaller soluble molecules and these species are reformed using a Pt/Al2O3 catalyst. The experiments show that increasing the acid concentration from 1% to 5% causes more than a twelve-fold increase in H2 concentration, with hydrogen a minor product accounting for 18% of the non-condensable gas phase and CO2 as the major product. In the presence of the Pt/Al2O3 reforming catalyst, both the selectivity and yield of hydrogen in the gas phase increase. This is accompanied by a noticeable decrease in carbon monoxide production. Comparison with other feeds such as glucose, wastepaper and ethylene glycol showed that the amount of hydrogen produced from biomass is of a comparable magnitude per gram of feed, although biomass yields more hydrogen per gram of carbohydrate than either glucose or wastepaper. Baseline experiments with only the catalysts in the absence of any biomass show no increase in the reactor system pressure when only water and helium are present, indicating that the observed hydrogen produced is sourced form the biomass.
Advisors/Committee Members: Dr. Christopher W. Jones (Committee Co-Chair), Dr. Pradeep K. Agrawal (Committee Co-Chair), Dr. Howard "Jeff" Empie (Committee Member), Dr. Sujit Banerjee (Committee Member).
Subjects/Keywords: XPS; Hydrogen chemisorption; Waste paper; Bioenergy; Pt/Al2O3; Glucose; H2SO4; Water-gas shift; Hydrogen as fuel; Biomass energy; Chemisorption
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APA (6th Edition):
Valenzuela, M. B. (2006). Batch Aqueous-phase Reforming of Lignocellulosic Biomass for Hydrogen Production. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/11624
Chicago Manual of Style (16th Edition):
Valenzuela, Mariefel Bayta. “Batch Aqueous-phase Reforming of Lignocellulosic Biomass for Hydrogen Production.” 2006. Masters Thesis, Georgia Tech. Accessed April 17, 2021.
http://hdl.handle.net/1853/11624.
MLA Handbook (7th Edition):
Valenzuela, Mariefel Bayta. “Batch Aqueous-phase Reforming of Lignocellulosic Biomass for Hydrogen Production.” 2006. Web. 17 Apr 2021.
Vancouver:
Valenzuela MB. Batch Aqueous-phase Reforming of Lignocellulosic Biomass for Hydrogen Production. [Internet] [Masters thesis]. Georgia Tech; 2006. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/1853/11624.
Council of Science Editors:
Valenzuela MB. Batch Aqueous-phase Reforming of Lignocellulosic Biomass for Hydrogen Production. [Masters Thesis]. Georgia Tech; 2006. Available from: http://hdl.handle.net/1853/11624
. 
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