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dc.contributor.advisorHernández-Maldonado, Arturo J.
dc.contributor.authorMarcano-González, Marietta E.
dc.date.accessioned2018-09-11T12:29:52Z
dc.date.available2018-09-11T12:29:52Z
dc.date.issued2015-12
dc.identifier.urihttps://hdl.handle.net/20.500.11801/834
dc.description.abstractUPRM-5 is a flexible titanium silicate and nano-porous adsorbent modified for the selective removal of CO2 from light gas mixtures. In this work, UPRM-5 was prepared using TPA and TBA cations as structure directing agents by synthesis methods employing convective and microwave heating. The materials were effectively detemplated and functionalized with Sr2+ cations. Characterization of the functionalized materials with XRD at temperatures ranging from 25-300°C showed that the UPRM-5 variants synthesized with TBA have better thermal stability that the variant synthesized with TPA. The 29Si MAS NMR experiments suggest that this may be due to fewer amount of structural faulting. In fact, high temperature in situ 29Si MAS NMR demonstrated instability of the Si environments with thermal contraction due to dehydration and further rehydration in both materials. Indexing of the XRD patterns showed, however, orthorhombic phases of UPRM-5 that remained at high temperatures. Diffusion time constants for the adsorption of CO2 and CH4 were estimated by using a volumetric phenomenological transport model that was corrected for particle size polydispersity. At optimum activation temperatures the kinetic selectivity of CO2 over CH4 were of 41 and 30 for Sr2+ -UPRM-5 (TBA) and (TPA), respectively. Test beds were also assembled at the NASA ARC and UPRM, to study the dynamic adsorption of CO2 from a gas mixture. The efficiencies of the test beds were calculated to be 77% for Sr2+ - UPRM-5 (TBA) and 65% for Sr2+ -UPRM-5 (TPA), over a range of CO2 concentrations of 500- 10000 ppm. A linear driving force (LDF) model was used to describe the CO2 concentrations at the exit of the bed. In terms of regeneration, thermal activation between adsorption cycles showed to be detrimental to the equilibrium and dynamic capacities when done in a consecutive fashion. Reducing the system pressure, on the other hand, appears to be sufficient to completely regenerate the adsorbents, which is a significant cost effective alternative.
dc.description.abstractUPRM-5 es un titano silicato flexible y un adsorbente nano-poroso modificado para la remoción selectiva de CO2 de mezcla de gases. En este trabajo, UPRM-5 se preparó usando cationes de TPA y de TBA como agentes directores de estructura mediante métodos de síntesis que emplean calor convectivo y de microondas. La remoción de la plantilla y la funcionalización con cationes Sr2+ se realizó de forma efectiva. La caracterización con XRD a temperaturas de 25-300°C de los materiales funcionalizados, mostró que la variante de UPRM-5 sintetizada con TBA tiene mejor estabilidad termal que la variante sintetizada con TPA. Los experimentos de 29Si MAS NMR sugieren que esto puede ser debido a una menor cantidad de fallas presentes en la estructura. Experimentos in situ a altas temperaturas de 29Si MAS NMR demostraron la inestabilidad de los ambientes de Si en ambos materiales con la contracción de la estructura debido a la deshidratación y posteriormente, con la re-hidratación de la estructura. Indexado de los patrones de XRD mostraron fases ortorrómbicas de UPRM-5 que se conservaron aún a altas temperaturas. Constantes de tiempo de difusión para la adsorción de CO2 y CH4 se estimaron mediante el uso de un modelo de transporte fenomenológico volumétrico que se corrigió para polidispersidad en el tamaño de partícula. A temperaturas óptimas de activación las selectividades cinéticas de CO2 sobre CH4 son 41 y 30 para Sr2+ -UPRM-5 (TBA) y (TPA), respectivamente. Lechos empacados de prueba para estudiar la adsorción dinámica de CO2 en mezcla de gases se ensamblaron en el NASA ARC y el RUM. Las eficiencias de los lechos de pruebas fueron de 77% para Sr2+ -UPRM5 (TBA) y 65% y Sr2+ -UPRM-5 (TPA), en un rango de concentraciones de CO2 de 500 a 10000ppm. Un modelo de fuerza de accionamiento lineal (LDF) se utilizó para describir las concentraciones de CO2 a la salida del lecho. En cuanto a la regeneración, el tratamiento termal entre ciclos de adsorción mostró ser perjudicial para la capacidad de adsorción dinámica y en equilibrio cuando se hace de manera consecutiva. La reducción de la presión del sistema, por otro lado, parece ser suficiente para regenerar completamente los adsorbentes, lo cual constituye una alternativa más costo-efectiva.
dc.description.sponsorshipNational Aeronautics and Space Administration under Grant No. NNX09AV05A. Partial support was also provided by the National Science Foundation (NSF) under Grant No. HRD 0833112 (CREST Program). The PR-LSAMP Bridge to the Doctorate Program, the Puerto Rico NASA Space Grant Graduate Fellowships Program as well as the NSF-sponsored Puerto Rico Institute for Functional Materials Graduate Fellowships Program under Grant EPS-1002410. The Dr. Riqiang Fu for the NMR measurements performed at the National High Magnetic Field Laboratory (NHMFL) supported by NSF Cooperative Agreement No. DMR-0654118 and DMR-1157490, the State of Florida, and the U.S. Department of Energy.en_US
dc.language.isoenen_US
dc.subjectNovel Titanium Silicate Porous Materialsen_US
dc.subject.lcshCarbon dioxide--Absorption and adsorptionen_US
dc.subject.lcshTitanium--Synthesisen_US
dc.titleNovel titanium silicate porous materials: Synthesis using large structure directing agents, functionalization and evaluation for carbon dioxide adsorption-based applicationsen_US
dc.typeDissertationen_US
dc.rights.licenseAll rights reserveden_US
dc.rights.holder(c) 2015 Marietta Estefanía Marcano-Gonzálezen_US
dc.contributor.committeeHwang, Sangchul
dc.contributor.committeeMartinez-Iñesta, María M.
dc.contributor.committeeZapata-López, Raúl E.
dc.contributor.representativeCalcagno, Bárbara O.
thesis.degree.levelPh.D.en_US
thesis.degree.disciplineCivil Engineeringen_US
dc.contributor.collegeCollege of Engineeringen_US
dc.contributor.departmentDepartment of Civil Engineeringen_US
dc.description.graduationSemesterFallen_US
dc.description.graduationYear2015en_US


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