Metal Organic Frameworks (MOFs) are a class of porous materials that are predominantly obtained as powders and have been investigated as a solid sorbent for gas separation or carbon capture applications from combustion exhaust gases. The manufacturing of products with MOFs to use them for real life applications is still a major problem. The most common productization method used is to form pellets of the powder MOFs. This has a limitation on the product shape which makes it difficult for it to be used in gas separation applications. This study focuses on using additive manufacturing technique to give MOFs a lattice (mesh-like) geometry which is useful for gas separation applications as the mixture of gases would be able to pass through the lattice structure and be separated due to the inherent MOF properties and characteristics. Two MOFs based on magnesium and manganese salts have been studied in this project. An extrudable paste developed using alginate gel as a binder with these MOFs. With alterations in paste formulations and 3D printer parameters, lattice structures were printed using the two MOFs. CO2 and N2 gas uptakes were measured showing that the structure adsorbs CO2 gas to a higher extend which results in the separation of N2 gas in both materials. When compared to their pristine powder form, other properties of the MOFs such as crystallinity, microstructure, reusability and surface area remain to be preserved after being 3D printed in both cases.

It is very important today to address the impacts of climate change as its effects can be observed every day. Nowadays many scientists believe that earth's climate is changing as a result of human-caused greenhouse gas emissions such as carbon dioxide and methane. Global energy demand is also rapidly evolving. A sustainable approach that balances economic growth with social and environmental responsibility should be considered as an effective and long-term strategy. Carbon dioxide is the foremost greenhouse gas of anthropogenic origin, responsible for the majority of the earth's warming effects. It is estimated that around 60% of the global warming impact can be traced back to the release of carbon dioxide into the atmosphere. Lowering methane emissions offers a range of notable advantages in terms of energy, safety, economy, and the environment. Firstly, since methane is a potent greenhouse gas (25 times more powerful than CO2 over a 100-year period), reducing methane emissions will contribute significantly to mitigating climate change in the short term. Additionally, methane is the primary component of natural gas and biogas, which means collecting and utilizing methane can be a valuable source of clean energy that fosters local economic growth and minimizes local environmental pollution. Generating energy through methane recovery eliminates the need for traditional energy resources, thus lessening end-user and power plant CO2 and air pollutant emissions. Physical adsorption separation processes have proven to be an effective technique for simultaneous carbon dioxide capture and methane enrichment applications. The objective of this study is to conduct a thorough assessment of the adsorption separation of methane and carbon dioxide gases employing a commercially available carbon molecular sieve, CMS(C), and an activated carbon, AC(B). The accomplishment of the objective involved conducting an in-depth characterization of the adsorbents. Part of the characterization included measurements of the internal surface area and pore size distributions, as well as the measurements of the equilibrium adsorption isotherms using gravimetric techniques. These isotherms enabled detailed kinetic analyses, such as evaluating diffusivity and mass transfer coefficients at various temperatures and pressure steps. The prediction of binary isotherms were based on theoretical models, which can describe the gas mixture adsorption equilibria using pure component equilibrium data. Breakthrough curves were generated to describe the dynamic response of an adsorption column under different pressures, temperatures, and flow rates. A mechanistic model was developed utilizing gPROMS simulation software for adsorption breakthrough process and it was validated by comparing its results to the experimental breakthrough curves. Parametric studies were conducted to determine the optimal operating conditions for gas adsorption separation of CO2 and CH4 gases. By examining the data obtained from breakthrough curves, pure and predicted binary adsorption equilibria, we calculated adsorption capacities, selectivity, sorbent selection parameter (S parameter), and the adsorbent performance indicator (API). These calculations were carried out to evaluate the initial potential for gas adsorption separation of the carbon molecular sieve (CMS(C)) and the activated carbon (AC(B)) under a range of operating conditions. Increasing pressure, decreasing temperature, and reduced feed flow improved breakthrough time and adsorption capacity for both gases on these adsorbents. CMS(C) showed superior selectivity, while AC(B) had a higher API value at specific conditions. The API was considered a more practical parameter for evaluating the initial gas separation potential. CMS(C) proved to be the better choice for methane purification, achieving the longest purification time under optimal conditions. Additionally, the study explored the kinetic behavior of methane and carbon dioxide with these adsorbent materials, revealing faster carbon dioxide uptake rates and the potential advantages of activated carbon in reducing adsorption/desorption cycle times in separation processes. At a pressure of 1 atm, a temperature of 294 K, and a flow rate of 400 ml min-1, CMS(C) had the highest values of selectivity and the S parameter, while AC(B) had the highest API value at 9 atm of pressure, a temperature of 294 K, and a flow rate of 400 ml min-1. The API was considered a more practical parameter for evaluating the initial gas separation potential. CMS(C) proved to be the better choice for methane purification, achieving the longest purification time of 420 seconds at a pressure of 9 atm, a temperature of 294 K, and a flow rate of 400 ml min-1. Additionally, the study explored the kinetic behavior of methane and carbon dioxide with these adsorbent materials, revealing faster carbon dioxide uptake rates and the potential advantages of activated carbon in reducing adsorption/desorption cycle times in separation processes. The analysis of the study, when compared to existing literature, reveals a coherent and logical progression. Our results align with similar studies, validating key points such as the improvement of methane purification through reduced feed flow rates and increased pressures, enhanced adsorption separation performance at lower temperatures and pressures, the superior adsorption capacity of activated carbon over carbon molecular sieves, and the greater selectivity of carbon molecular sieves over activated carbon and faster diffusion of carbon dioxide compared to methane within the carbon porous materials.

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Phenylindane monomers 5(6)-amino-1-(4-aminophenyl)-1,3,3-trimethylindane (DAPI), 5,6-diamino-1-(4-aminophenyl)-1,3,3-trimethylindane (TAPI) and 6-hydroxy-1-(4-hydroxyphenyl)-1,3,3-trimethylindane (DHPI) were synthesized and characterized. DAPI, as well as other diamines, were then utilized in solution step polycondensation with a number of commercially available dianhydrides using either the two-step ester-acid solution imidization or the high temperature solution imidization routes. High molecular weight soluble fully cyclized polyimides were successfully synthesized using a 1:1 molar ratio of dianhydride to diamine. The polyimides were film forming and were characterized by size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and selective gas permeation methods, as well as other techniques. The O2 permeation and O2/N2 selectivity values obtained for materials prepared in this thesis are discussed in relation to the concept of an "upper bound", as defined in the literature concerning gas separation membranes. The series of polyimides based on DAPI and several dianhydrides were found to have high glass transition temperatures (247°C-368°C) and very good short-term thermal stability as shown by TGA, despite the partially aliphatic character of DAPI. The 5,5'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzenefurandione (6FDA)/DAPI system also exhibited low weight loss under nitrogen at 400°C, which was comparable to that of a wholly aromatic polyimide based on 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA)/4,4'-oxydianiline (ODA) which is known to have high thermal stability. In addition, the 6FDA/DAPI polyimides had a refractive index value of 1.571 from which the dielectric constant was calculated, giving an attractively low estimated value of 2.47. The rigid, bulky and isomeric structure of DAPI in the repeat unit imparted film forming characteristics that allowed production of solvent cast membranes which displayed a range of O2 permeability and O2/N2 selectivity characteristics. High O2 permeabilities were observed for polyimides in which the DAPI structure predominated in relation to the overall polymer repeat unit, i.e. in combination with low molar mass dianhydrides. The more flexible dianhydrides afforded a greater degree of molecular freedom and were thought to result in a more tightly packed polymer conformation which decreased the rate of gas penetration through thin films. The DAPI/3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) system showed the best combination of O2 permeability and O2/N2 selectivity values (2.8Ba and 7.3, respectively). Modest variations in the DAPI isomeric ratio did not significantly effect the gas permselectivity properties. High molecular weight polyimides based on DAPI and BTDA were synthesized by three different routes. The ester-acid and thermal imidization methods produced polyimides with the highest Tgs and best thermal stability in air, as compared to the chemical imidization procedure. For example, a Tg increase of 22°C and a 68°C increase in the 5% weight loss were found for the ester-acid imidized DAPI/BTDA polyimide over those found for the chemically imidized version. The higher Tg and 5% weight loss values were attributed to the elimination of residual uncyclized amide acid moieties. Polyimides derived from 6FDA were synthesized by the high temperature solution imidization method. Thin films, cast from NMP, were tough and creasable and afforded high Tg (>295°C) systems with good thermal stability. When combined with rigid diamines, 6FDA contributed to high O2 permeation and moderate O2/N2 selectivity. The high O2 permeability was ascribed to hindered interchain packing attributed to the bulky CF3 groups. The exceptionally high oxygen permeability and O2/N2 selectivity values of the 9,9-bis(4-aminophenyl) fluorene (FDA)/6FDA system, were near the desirable "upper bound" for gas separation membrane materials, while those of 3,7-diamino-2,8-dimethyl-dibenzothiophene-5,5-dioxide (DDBT)/6FDA were actually above the upper bound. High performance polymers based on 4,4'-bis [4-(3,4-dicarboxyphenoxy)]biphenyl dianhydride (BPEDA), 2,2'-bis [4-(3,4-dicarboxyphenoxy)phenyl] propane dianhydride (BPADA), 2,2-bis(3-amino-4-methylphenyl)hexafluoroisopropylidene dianhydride (Bis-AT-AF) and 3,7-diamino-2,8-dimethyl-dibenxothiophene-5,5-dioxide (DDBT) were also synthesized in this work. Additionally, they were characterized with regard to molecular weight, glass transition temperature, and thermal stability. Polyimide systems containing hydroxyl moieties in the repeat unit were also investigated. Incorporation of hydroxyl moieties in the repeat unit enhanced chain stiffness via intermolecular hydrogen bonding and showed Tg increases of ~30°C Hydroxyl moieties also decreased the thermal stability values typically observed for polyimides. High O2/N2 selectivity was achieved with all of the 4,4'-diaminobiphenyl-3,3'-diol (HAB) containing polymers. However, these materials also had low O2 permeabilities, which suggested a tightly packed structure, possibly facilitated by hydrogen bonding. In contrast to suggestions in the literature, the comparison between a polyimide having pendant hydroxyl groups and another having the same repeat unit without them did not reveal a significant change in permselectivity behavior. The synthesis, characterization and crosslinking behavior of functional polyimides containing phenol, amine and acetylene moieties are also described. A crosslinking reaction of oligomers containing phenol moieties with a tetrafunctional epoxy resin was achieved 100°C below the "dry" glass transition temperature and was attributed to residual solvent. Utilization of this crosslinking mechanism could allow membrane optimization by investigating the influence of a number of variables, such as the concentration of the phenolic moiety, epoxy weight percent, catalyst concentration and residual solvent content. / Ph. D.

Nanosized Ti0₂ rich domains were generated in-situ within poly(amide-imide) (PAl) and 6F-poly(amide-imide) (6FPAl) by a sol-gel process. The composite films showed a high optical transparency. The morphology of the Ti0₂ rich domains was observed by transmission electron microscopy (TEM). The Ti0₂ rich domains were well dispersed within the poly(amide-imide) and 6F-poly(amide-imide) matrices and were 5 nm to 50 nm in size. Limited study was also carried out for the fabrication of the P AI/Si0₂ and PAI/fi0₂-Si0₂ composites. It was found that nanosized Si0₂ rich domains were difficult to form within the poly(amide-imide) matrix, although the Si0₂ could be bonded with the Ti0₂, forming nanosized domains within the poly(amide-imide) matrix. The PAI/Ti0₂ composites showed an increased glass transition temperature, and an increased rubbery plateau modulus, in comparison to the unfilled poly(amide-imide). Wide Angle X- ray Diffraction (W AXD) study and Differential Scanning Calorimetry (DSC) analysis suggest that the Ti0₂ filled poly( amide-imide) have a lower crystallinity as compared to the unfilled poly(amide-imide). The dynamic mechanical properties in rubbery regions suggest that Ti0₂ domains function as physical crosslinks, increasing the rubbery plateau modulus with increasing Ti0₂ content. This behavior can be explained by the theory of rubbery elasticity. The actual formation of the nanosized Ti0₂ and Ti0₂-Si0₂ rich domains was explained in terms of hydrogen bonding effects between the polymer, the solvent and the inorganic components. / Ph. D.