Capillary Condensation and Freezing of Simple Fluids Confined in Cylindrical Nanopores

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dc.contributor.advisor Keith E. Gubbins, Committee Chair en_US
dc.contributor.advisor Carol K. Hall, Committee Member en_US
dc.contributor.advisor Orlin D. Velev, Committee Member en_US
dc.contributor.advisor Donald W. Brenner, Committee Member en_US Hung, Francisco Rodolfo en_US 2010-04-02T18:29:31Z 2010-04-02T18:29:31Z 2005-09-22 en_US
dc.identifier.other etd-08092005-232433 en_US
dc.description.abstract We present a molecular simulation study aimed at understanding the phase behavior of pure simple fluids, when they are confined inside nanopores of cylindrical geometry. In this situation, new surface-driven phases can appear, and phase transitions typical of bulk systems (gas-liquid, freezing) can be shifted to different conditions. A fundamental understanding of these phenomena is necessary for applications in separations, catalysis and nanotechnology. Studies of these phenomena can also provide important insights on the effect of surface forces, confinement and reduced dimensionality on the phase behavior of host molecules. We have performed two independent, but directly related studies: (1) freezing of carbon tetrachloride within multi-walled carbon nanotubes (MWCNT) of different diameters, and (2) capillary condensation and freezing of krypton within templated mesoporous silica materials (MCM-41). MWCNT and MCM-41 are representative of materials with strongly and weakly attractive walls, respectively. In the first part of this project, the structure and thermodynamic stability of the confined phases, as well as the temperatures and the order of the phase transitions were determined using dielectric relaxation spectroscopy measurements and Monte Carlo simulations in the grand canonical ensemble. A rich phase behavior with multiple transition temperatures was observed for such systems. In the second part of this project we developed realistic, atomistic models of MCM-41 type materials that include pore surface roughness and morphological defects in agreement with experimental results. Grand Canonical Monte Carlo simulations show that these variables have a profound influence on gas-liquid and freezing transitions in confinement. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Monte Carlo en_US
dc.subject carbon nanotubes en_US
dc.subject dielectric relaxation spectroscopy en_US
dc.subject adsorption en_US
dc.subject MCM-41 en_US
dc.subject confinement en_US
dc.subject molecular simulation en_US
dc.subject Phase behavior en_US
dc.title Capillary Condensation and Freezing of Simple Fluids Confined in Cylindrical Nanopores en_US PhD en_US dissertation en_US Chemical Engineering en_US

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