Improving the chemical and mechanical stability of inorganic porous materials in order to achieve real-world usability
Date
2023
Authors
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Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Chapter 2 investigates the functionalization of MIL-101 in order to achieve improved chemical stability. By incorporating various amide-functionalized ligands into MIL-101, a better understanding was achieved of how the specific functional groups impacted the three-dimensional material’s ability to withstand aqueous solutions that exhibited various levels of acidity. This research demonstrated that the inclusion of long hydrocarbon chains within the framework could improve its resistance to structural damage. ☐ Chapter 3 looks at improving the volumetric adsorption capabilities of UiO-66 through compaction and exploring how incorporating various functional groups into this MOF effects its ability to withstand compaction while retaining porosity and preserving structural attributes such as surface area and crystallinity. To better understand how UiO-66 and its functionalized counterparts can withstand a compressive force, pellets were formed using pressures ranging from 0.15 GPa to 1.01 GPa and by using a gas adsorption analyzer it was determined that each material tested. With the exception of a long-chain functionalized analog, all of the materials investigated showed an improved volumetric surface area when compared to the non-compressed starting material. ☐ Chapter 4 focuses on the incorporation of bridging and non-bridging structural elements into a MOF in order to act as mechanical bracing that does not necessary rely on bonding as a means to tune the structural stability of the materials. In some cases, by introducing additional chemical components into these three-dimensional frameworks, pore collapse is prevented while a compressive force is applied to the material, which is likely a result of the added steric hinderance throughout the porous structure. By adsorbing iodine onto the UiO-66 framework, a reduction in gravimetric surface area loss is achieved, as compared to the pristine UiO-66 (22% as opposed to a 65% surface area loss for non-iodized), when densified using a 0.65 GPa compressive force. An alternate method of increasing mechanical stability is demonstrated by irreversibly binding various secondary metals onto the surface of a carboxylate-functionalized material, UiO-66-(CO2H)2.
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Keywords
Inorganic porous materials, Chemical stability, Mechanical stability, Aqueous solutions, Hydrocarbon chains