Covalent organic framework modifications for gas storage and separation applications
dc.contributor.advisor | Gennett, Thomas | |
dc.contributor.author | Mow, Rachel E. | |
dc.date.accessioned | 2023-04-26T21:40:29Z | |
dc.date.available | 2023-04-26T21:40:29Z | |
dc.date.issued | 2022 | |
dc.identifier | Mow_mines_0052E_12513.pdf | |
dc.identifier | T 9453 | |
dc.identifier.uri | https://hdl.handle.net/11124/176609 | |
dc.description | Includes bibliographical references. | |
dc.description | 2022 Fall. | |
dc.description.abstract | The large surface areas, lightweight compositions, and excellent tunability of covalent organic frameworks (COFs) makes them promising materials for applications in gas storage and separation. However, the wide-scale applicability of COFs is limited by low volumetric capacities of the solid powders and low isosteric heats of adsorption for gases physisorbed to the COF surfaces. This work presents several modification strategies developed to improve the gas storage and separation properties of COFs. It is known that through the incorporation of metal sites one can improve the binding enthalpy of hydrogen and other gases in framework materials. This work describes a new synthetic strategy to incorporate open Cu(I) sites in COFs, along with in-depth characterization of Cu(I) π-backbonding interactions with hydrogen, ethylene and carbon monoxide. ”On-demand” gas desorption was achieved with UV exposure instead of thermal activation of the high enthalpy Cu(I)-gas interactions. A combination of experimental and computational techniques revealed this phenomenon was caused by both photothermal heating and disruption of π-backbonding through photoexcitation of electrons. A well-controlled synthesis of 3D COF colloids was also developed, resulting in nanometer-scale, spherical particles. The stability of these COF colloids was improved with surface-functionalization techniques, including tethering ionic liquid counter ions and robust polymer shells to the COF surface. Hydrogen diffusion was found to be kinetically limited below the glass transition temperature of a crosslinked polymer coating, thereby shifting desorption to significantly warmer temperatures. This discovery presents a unique method to control the temperature of gas adsorption and desorption in COFs using kinetics. Polymer-coated COF colloids were also loaded with Cu ions and activated at 200◦C without irreversible aggregation, facilitating the development of porous liquids with open Cu(I) sites. These Cu(I)-containing porous liquids adsorbed gases at ambient temperatures, where the material remained fluid. Additionally, porous liquids were formed from non Cu-containing COF colloids and demonstrated excellent carbon dioxide and methane uptake, with unique sorption properties compared to the Cu-loaded COFs. The combined gas uptake and fluidity of these materials makes them promising for applications in carbon capture and as hydrogen carriers. Overall, this work presents several modification strategies that greatly improve the properties of COFs for specific gas storage or separation applications. | |
dc.format.medium | born digital | |
dc.format.medium | doctoral dissertations | |
dc.language | English | |
dc.language.iso | eng | |
dc.publisher | Colorado School of Mines. Arthur Lakes Library | |
dc.relation.ispartof | 2022 - Mines Theses & Dissertations | |
dc.rights | Copyright of the original work is retained by the author. | |
dc.subject | covalent organic frameworks | |
dc.subject | Cu(I) | |
dc.subject | gas separation | |
dc.subject | gas storage | |
dc.subject | hydrogen | |
dc.subject | polymerization | |
dc.title | Covalent organic framework modifications for gas storage and separation applications | |
dc.type | Text | |
dc.date.updated | 2023-04-22T22:11:10Z | |
dc.contributor.committeemember | Braunecker, Wade | |
dc.contributor.committeemember | Sellinger, Alan | |
dc.contributor.committeemember | Wolden, Colin Andrew | |
thesis.degree.name | Doctor of Philosophy (Ph.D.) | |
thesis.degree.level | Doctoral | |
thesis.degree.discipline | Chemistry | |
thesis.degree.grantor | Colorado School of Mines |