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DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: The huge emissions of carbon dioxide from fossil fuel fired power plants and industrial plants over the last century have resulted in an increase of the atmospheric carbon dioxide concentration. Climatological modeling work has predicted severe climate disruption as a result of the trapping of heat due to CO{sub 2}. As an attempt to address this global warming effect, DOE has initiated the Vision 21 concept for future power plants. We first synthesized mesoporous aluminosilicates that have high surface area and parallel pore channels for membrane support materials. Later we synthesized microporous aluminosilicates as the potential thin membrane materials for selective CO{sub 2} adsorption. The pore size is controlled to be less that 1 nm so that the adsorption of CO{sub 2} on the pore wall will block the passage of N{sub 2}. Mesoporous and precipitated alumina were synthesized as the base material for CO{sub 2} adsorbent. The porous alumina is doped with Ba to enhance its CO{sub 2} affinity due to the basicity of Ba. It is shown by gas chromatograph (GC) that the addition of Ba enhances the separation CO{sub 2} from N{sub 2}. It was found that mesoporous alumina has larger specific surface area and better selectivity of CO{sub 2} than precipitated alumina. Ba improves the affinity of mesoporous alumina with CO{sub 2}. Phase may play an important role in selective adsorption of CO{sub 2}. It is speculated that mesoporous alumina is more reactive than precipitated alumina creating the xBaO {center_dot}Al{sub 2}O{sub 3} phase that may be more affinitive to CO{sub 2} than N{sub 2}. On the other hand, the barium aluminates phase (Ba{sub 3}Al{sub 2}O{sub 6}) in the mesoporous sample does not help the adsorption of CO{sub 2}. Microporous aluminosilicate was chosen as a suitable candidate for CO{sub 2}/N{sub 2} separation because the pore size is ...
Date: March 25, 2003
Creator: Shih, Wei-Heng; Patil, Tejas & Zhao, Qiang
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: The authors propose to use microporous silica as a suitable candidate for CO{sub 2}/N{sub 2} separation because the pore size is less than 10 {angstrom}. If a CO{sub 2}adsorbent is added to the microporous silica, the adsorption of CO{sub 2} can block the passage of N{sub 2} and an effective CO{sub 2}/N{sub 2} separator will be found. It was first demonstrated that microporous silica could be synthesized. The microporous silica was then impregnated with Ba(OH){sub 2}. The results of GC study showed that at temperatures between 50 C and 90 C, Ba-doped microporous silica can separate CO{sub 2} from N{sub 2} and the idea of a microporous membrane for CO{sub 2}/N{sub 2} separation is feasible. The new result gives strong support to the proposed research that was outlined in the Phase II proposal. They hope to be able to continue the research and build an effective CO{sub 2}/N{sub 2} membrane separator in the Phase II of this project.
Date: May 1, 2002
Creator: Shih, Wei-Heng; Zhao, Qiang & Patil, Tejas
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION

Description: Mesoporous and precipitated alumina were synthesized as the base material for CO{sub 2} adsorbent. The porous alumina is doped with Ba to enhance it CO{sub 2} affinity due to the basicity of Ba. it is shown by gas chromatograph (GC) that the addition of Ba enhances the separation CO{sub 2} from N{sub 2}. It was found that mesoporous alumina has larger specific surface area and better selectivity of CO{sub 2} than precipitated alumina. Ba improves the affinity of mesoporous alumina with CO{sub 2}. Phase may play an important role in selective adsorption of CO{sub 2}. It is speculated that mesoporous alumina is more reactive than precipitated alumina creating the xBaO {center_dot} Al{sub 2}O{sub 3} phase that may be more affinity to CO{sub 2} than N{sub 2}. On the other hand, the barium aluminate phase (Ba{sub 3}Al{sub 2}O{sub 6}) in the mesoporous sample does not help the adsorption of CO{sub 2}.
Date: May 1, 2002
Creator: Shih, Wei-Heng; Zhao, Qiang & Wang, Nanlin
Partner: UNT Libraries Government Documents Department

ULTRASENSITIVE HIGH-TEMPERATURE SELECTIVE GAS DETECTION USING PIEZOELECTRIC MICROCANTILEVERS

Description: We have obtained very promising results in the Phase I study. Specifically, for temperature effects, we have established that piezoelectric cantilever sensors could retain their resonance peak strength at high temperatures, i.e., the Q values of the resonance peaks remained above 10 even when the temperature was very close to the Curie temperature. This confirms that a piezoelectric cantilever sensor can be used as a sensor up to its Curie temperature. Furthermore, we have shown that the mass detection sensitivity remained unchanged at different temperatures. For selective gas detection, we have demonstrated selective NH{sub 3} detection using piezoelectric cantilever sensors coated with mesoporous SiO{sub 2}. For high-temperature sensor materials development, we have achieved highly oriented Sr-doped lead titanate thin films that possessed superior dielectric and ferroelectric properties. Such highly oriented films can be microfabricated into high-performance piezoelectric microcantilever sensors that can be used up to 490 C. We have accomplished the goal of Phase I study in exploring the various aspects of a high-temperature gas sensor. We propose to continue the study in Phase II to develop a sensor that is suitable for high-temperature applications using piezoelectrics with a high Curie temperature and by controlling the effects of temperature. The lead titanate based thin film developed in Phase I is good for applications up to 490 C. In phase II, we will develop lithium niobate thin film based cantilevers for applications up to 1000 C.
Date: March 5, 2004
Creator: Shih, Wan Y.; Patil, Tejas; Zhao, Qiang; Chiu, Yi-Shi & Shih, Wei-Heng
Partner: UNT Libraries Government Documents Department