Type
Text
Type
Dissertation
Advisor
Parise, John B | Phillips, Brian | Ehm, Lars | Rogers, Deanne | Cahill, Chris.
Date
2015-05-01
Keywords
carbon dioxide, crystallography, diffraction, gas adsorption, hydrocarbon, metal organic framework | Mineralogy
Department
Department of Geosciences.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/77648
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Selective adsorption and sequestration of carbon dioxide from sources of anthropogenic emissions is important to mitigate the growing level of the atmospheric CO2. Solid state adsorbents, such as metal organic frameworks (MOFs), are proposed as an alternative to the currently used toxic and corrosive alkanolamine solutions. The aim of this work was to understand the interactions between adsorbed gases and a pore surface of crystalline MOFs at a molecular level, and identify the connection between geometry and gas selectivity. In contrast to current trends in the design of MOFs, we described the unique mechanism responsible for a high CO2/N2 adsorption selectivity in a Ca-based MOF: Ca(sdb), (sdb: 4,4’-sulfonyldibenzoate), even in the presence of water in the gas stream. Single crystal XRD experiments of gas-loaded samples revealed that the v-shaped linker provides a “pi-pocket†formed by two phenyl rings, and that CO2 locate between the rings, resulting in a high heat of adsorption. To determine the gas adsorption performance in situ in the presence of water, we used X-ray Diffraction (XRD) simultaneously with differential scanning calorimetry (XRD-DSC). The XRD-DSC technique allows measurements of heat flow that provide enthalpy of adsorption, while at the same time XRD allows evaluation of structural responses during MOF activation and gas adsorption. We also used XRD-DSC to determine the performance of Cd(sdb), the Cd-based analogue of Ca(sdb): Cd(sdb) shows a high selectivity for CO2 over N2. In situ vacuum-swing XRD-DSC allowed us to determine the heat of adsorption values of the adsorbate; results of these studies were consistent with the pi–CO2 interaction as the origin of the selectivity. The newly described “pi-pocket†is a potential site for a selective adsorption of gases other than CO2. Hydrocarbon gases (C2Hn), such as ethane, ethylene and acetylene, were adsorbed on Ca(sdb) and on another Ca-based MOF: Ca(tcpb) [tcpb: 1,2,4,5-tetrakis(4-carboxyphenyl)benzene] with a high measured energy of interaction. Structural data suggest that C2Hn interact with the organic linkers within the MOF frameworks through C-H…pi and C-H…O interactions. The knowledge acquired here can promote systematic synthetic searches for novel materials that can serve as selective solid-state adsorbents. Finally, the formation of Ca-based Metal Organic Frameworks was studied using different structural isomers of pyridinedicarboxylic acid. Nine MOF materials were synthesized and structurally analyzed. The atomic arrangements in the crystal structure of resultant MOFs are based on a variety of the inorganic structural motifs, ranging from isolated polyhedra to infinite chains, a layer or a 3-D connectivity, depending on the linker geometry and the synthetic condition. | 231 pages
Recommended Citation
Plonka, Anna Monika, "Structural Characterization of Gas Adsorption in Metal Organic Frameworks" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 3441.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/3441