Design of oligomer-modified nanoporous membranes for solubility-based gas separation /
Membranes are increasingly replacing the traditional methods of gas separation, such as distillation and absorption. One very important class of gas separation is the removal of dilute heavy species from a light gas feed stream. Examples include the removal of volatile organic compounds (VOCs) from...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=765069781&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Membranes are increasingly replacing the traditional methods of gas separation, such as distillation and absorption. One very important class of gas separation is the removal of dilute heavy species from a light gas feed stream. Examples include the removal of volatile organic compounds (VOCs) from air and the removal of heavier hydrocarbons from natural gas. Due to economic and process driving forces, membranes for this type of separation must be permselective for the heavier, dilute component. Either polymeric or porous membranes might be used for this purpose. Generally speaking, polymeric materials exhibit high selectivity at low permeation rates, while porous inorganic membranes are characterized by low selectivity factors at high permeation rates. An alternative is to produce a polymer-inorganic hybrid membrane that combines the best characteristics of both; that is the subject of this work. Hybrid organic/inorganic membranes were prepared by the surface-derivatization of commercially available mesoporous alumina membranes with octadecyltrichlorosilane (OTS) and melamine based D2-Cl dendron. Ideal and mixed gas selectivities for propane/nitrogen and butane/methane systems were obtained at different inlet feed pressures and compositions for OTS modified membranes. For these mixtures, the mixed gas selectivities were generally greater than or equal to the corresponding ideal values. Interestingly, the dependence of mixed gas selectivity on feed pressure was qualitatively different for the two different gas pairs. Apparent competitive and cooperative effects between the permeating gas species were observed under different conditions. Separation factors for the toluene/nitrogen system were obtained for membranes modified with OTS and D2 dendrons. The separation performance of the dendron-modified membrane was greatly superior to that of the OTS modified membrane, and was comparable to the currently best known polymers being used for this type of application. A study was also conducted to determine the influence of surface hydration and treatment chemistry on the formation of surface-derivatized hybrid membrane with organosilanes. Several surface-analytical techniques were employed to elucidate the effect of these synthesis variables. This study demonstrates that the synthesis of hybrid membranes with tunable free volume and surface chemistry is feasible and that high performance hybrid membranes may be designed for solubility-based separations. |
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| Item Description: | Vita. "Major Subject: Chemical Engineering". |
| Physical Description: | xii, 139 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 130-138). |