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Polymer-silica Hybrids for Separation of CO2 and Catalysis of Organic Reactions

Silva Mojica, Ernesto
http://rave.ohiolink.edu/etdc/view?acc_num=akron1398439043

Abstract Details

2014, Doctor of Philosophy, University of Akron, Polymer Science.
Porous materials comprising polymeric and inorganic segments have attracted interest from the scientific community due to their unique properties and functionalities. The physical and chemical characteristics of these materials can be effectively exploited for adsorption applications. This dissertation covers the experimental techniques for fabrication of poly(vinyl alcohol) (PVA) and silica (SiO2) porous supports, and their functionalization with polyamines for developing adsorbents with potential applications in separation of CO2 and catalysis of organic reactions. The supports were synthesized by processes involving (i) covalent cross-linking of PVA, (ii) hydrolysis and poly-condensation of silica precursors (i,e,. sol-gel synthesis), and formation of porous structures via (iii) direct templating and (iv) phase inversion techniques. Their physical structure was controlled by the proper combination of the preparation procedures, which resulted in micro-structured porous materials in the form of micro-particles, membranes, and pellets. Their adsorption characteristics were tailored by functionalization with polyethyleneimine (PEI), and their physicochemical properties were characterized by vibrational spectroscopy (FTIR, UV-vis), microscopy (SEM), calorimetry (TGA, DSC), and adsorption techniques (BET, step-switch adsorption). Spectroscopic investigations of the interfacial cross-linking reactions of PEI and PVA with glutaraldehyde (GA) revealed that PEI catalyzes the cross-linking reactions of PVA in absence of external acid catalysts. In-situ IR spectroscopy coupled with a focal plane array (FPA) image detector allowed the characterization of a gradient interface on a PEI/PVA composite membrane and the investigation of the cross-linking reactions as a function of time and position. The results served as a basis to postulate possible intermediates, and propose the reaction mechanisms. The formulation of amine-functionalized CO2 capture sorbents was based on the spectroscopic investigation of the interactions of CO2 with amine molecules under simulated CO2 capture conditions. Industrial CO2 capture processes involve fluidization and require degradation-resistant sorbents in the form of pellets. Agglomeration of silica-based CO2 capture sorbents involved the formulation of a polymer binder solution and the design of a scalable pelletization process. The characterization of these pellets revealed the formation of a CO2-permeable polymer-silica network, which is resistant to attrition, and exhibits similar CO2 capture and degradation performance as the non-pelletized sorbents. The performance of these sorbents and pellets was tested in lab-scale and bench-scale adsorption units, using in-house fabricated fixed-bed and fluidized-bed reactors. A compartmental modeling technique was used to simulate the CO2 adsorption process and to elucidate the kinetic and thermodynamic parameters that impact the commercial viability of emerging CO2 capture technologies. The fundamental concepts and experimental techniques developed for the preparation of CO2 capture sorbents served as a basis for fabricating amine-functionalized polymer-silica hybrids for applications in catalysis of organic reactions. (i) Basic catalysts for carbon-carbon addition reactions were prepared by immobilization of amine molecules on silica supports. The activity of these catalysts and the mechanisms of base-catalyzed organic condensation reactions were investigated by an in-situ FTIR micro-scale reactor. (ii) Particle-loaded PVA composite membranes were selected for immobilization of glucose oxidase (GOx). GOx was immobilized by adsorption at pH values between 3.5 and 7.1. The results showed that adsorption was primarily achieved via hydrophobic interactions, and that PVA membranes loaded with amine-functionalized particles could help retain the activity of immobilized GOx by providing a proper hydrophilic/hydrophobic balance to the immobilized enzyme’s micro-environment.
Steven Chuang, Dr. (Advisor)
Matthew Becker, Dr. (Committee Member)
Mesfin Tsige, Dr. (Committee Member)
Darrell Reneker, Dr. (Committee Member)
Jie Zheng, Dr. (Committee Member)
217 p.
Chemical Engineering; Chemistry; Climate Change; Energy; Engineering; Environmental Engineering; Experiments; Fluid Dynamics; Materials Science; Molecules; Nanotechnology; Organic Chemistry; Polymer Chemistry; Polymers; Scientific Imaging; Technology
Adsorption, CO2, capture, polymer, silica, hybrids, cross-linking, porous, catalysis, compartmental modeling, enzyme immobilization, phase inversion, pellet, pelletization, separation, PVA, PEI, amine, sorbent, membrane, IR, infrared, imaging, SBA-15, FPA

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Citations

  • Silva Mojica, E. (2014). Polymer-silica Hybrids for Separation of CO2 and Catalysis of Organic Reactions [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398439043

    APA Style (7th edition)

  • Silva Mojica, Ernesto. Polymer-silica Hybrids for Separation of CO2 and Catalysis of Organic Reactions. 2014. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1398439043.

    MLA Style (8th edition)

  • Silva Mojica, Ernesto. "Polymer-silica Hybrids for Separation of CO2 and Catalysis of Organic Reactions." Doctoral dissertation, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398439043

    Chicago Manual of Style (17th edition)

akron1398439043
931
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This open access ETD is published by University of Akron and OhioLINK.