Design and construction of a sulfur dioxide gas permeation device and further screening of metal-organic frameworks for the removal of harmful gases from the air

Abstract

Metal-organic frameworks (MOFs) are a class of porous materials comprised of metal nodes and organic linkers. These tunable materials possess high accessible surface area, making them attractive for a variety of applications (e.g., gas separations, gas storage, and catalysis). The primary focus in this thesis has been to examine the experimental design and the application of MOFs for the sorption and separation of harmful gases. This thesis will focus on two different topics. Firstly, the application of MOFs for the sorption of sulfur dioxide (SO₂) gas was explored. SO₂ is a criteria air pollutant, being one of the most common air pollutants monitored by the government. SO₂ gas is harmful to both human health (e.g., respiratory ailments) and the environment (e.g., acid rain). The primary anthropogenic source of SO₂ in the environment is the combustion of fossil fuels. Existing pre- and post- combustion methods for the removal of SO₂ are costly and are unable to meet stringent environmental regulations. These drawbacks in pre-existing methods/materials increase the demand for more effective and lower cost alternatives. The challenge with studying SO₂ adsorption/separation is in the toxicity and corrosive nature of the gas. This makes it difficult to study SO₂ at environmental concentrations. With that in mind, we aimed to create a tunable SO₂ source to test MOFs for their sorption potential of gaseous SO₂. Chapter 2 will thoroughly discuss the experiments that were implemented in creating an SO₂ gas source. Secondly, MOFs were investigated for their potential to separate carbon monoxide (CO) from other gases on the basis of size exclusion. Our primary interest has been to separate carbon dioxide (CO₂) from CO. This is due to the risks associated with incomplete combustion that leads to formation of CO. CO is a colorless and odorless gas that, even at low concentrations, can be extremely detrimental to human health. Therefore, newly discovered MOF systems were investigated for their ability to sieve CO from other common gases (CO₂ and N₂) via their unique pore apertures. The synthesis, crystal structure, and separation capabilities of both Zn₃(NH₂BDC)₃DABCO and Zn₂Cd(NH₂BDC)₃DABCO will be discussed in-depth in Chapter 3.