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TRANSPORT AND SEPARATION OF GAS MIXTURES THROUGH CARBON
MOLECULAR SIEVE MEMBRANES AT SUBCRITICAL AND
SUPERCRITICAL CONDITIONS
By
Khadijeh MolaaiNezhad
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMICAL ENGINEERING)
December 2006
Copyright 2006 Khadijeh MolaaiNezhad
Object Description
| Title | Transport and separation of gas mixtures through carbon |
| Author | Molaai-Nezhad, Khadijeh |
| Author email | molaaine@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2006-08-01 |
| Date submitted | 2006 |
| Restricted until | Unrestricted |
| Date published | 2006-11-20 |
| Advisor (committee chair) | Shing, Katherine |
| Advisor (committee member) |
Lee, C. Ted Pirbazari, Massoud |
| Abstract | The investigation of the fundamental understanding of a combined membrane/supercritical separation process is the goal for this study. Analysis and presentation of the permeation data provide information about the performance of this advanced separation process. There are tremendous potential advantages to reap using supercritical fluid solvents for membrane separations. The solute molecules can have solubility in the supercritical fluids approaching those seen in liquids, while the mass transfer coefficients of the solutes can be comparable to that seen in gaseous solvents. Therefore, membrane fouling could be diminished while mass transfer limited separations could be enhanced using a supercritical fluid solvent process.; The long-term goal is to achieve reliable engineering and design of improved membranes which can be used to remove solutes continuously from supercritical solvents such as carbon dioxide. Utilization of such membranes would produce significant reductions in operating costs compared with the energy-intensive expansion/re-compression cycle conventionally utilized in order to separate solutes from supercritical solvents.; In this study, a high-pressure permeation system that permits reliable testing of membranes for supercritical applications was designed and constructed. Techniques for preparation and characterization of carbon membranes effective in gas separations under high pressure and high temperature conditions were developed. Experimentally observed transport properties and separation efficacy were related and correlated with membrane structure. The experimental results and mathematical analysis of single gas transport based on Maxwell-Stefan formulations through membrane under sub-critical and supercritical conditions were presented. The model shows deviation of experimental data at high pressure.; Several hydrocarbon/carbon-dioxide mixture systems were studied. Methane, ethane, propane and hexane were chosen to examine the effect of molecular size on the separation performance. The effect of temperature and pressure on the permeation properties in the sub critical and supercritical regimes was studied. A key observation from the data is that the amount of adsorption increases as the hydrocarbon molecular weight increases. For the carbon membranes studied, the absorbed hydrocarbon can block the CO2 permeation through the pores especially at lower temperatures. |
| Keyword | supercritical fluids; separation; carbon membrane |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m175 |
| Rights | Molaai-Nezhad, Khadijeh |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-MolaaiNezhad-20061120 |
| Archival file | uscthesesreloadpub_Volume26/etd-MolaaiNezhad-20061120.pdf |
Description
| Title | Page 1 |
| Full text | TRANSPORT AND SEPARATION OF GAS MIXTURES THROUGH CARBON MOLECULAR SIEVE MEMBRANES AT SUBCRITICAL AND SUPERCRITICAL CONDITIONS By Khadijeh MolaaiNezhad A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (CHEMICAL ENGINEERING) December 2006 Copyright 2006 Khadijeh MolaaiNezhad |
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