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This study evaluated the effectiveness of using cellulosic adsorbents to dehydrate 95 wt% ethanol/5 wt% water mixture. Hardwood sawdust, kenaf core, and bleached wood pulp were used as adsorbents in both liquid phase and gas phase experiments. All three adsorbents preferentially adsorbed water compared to ethanol. Bleached wood pulp exhibited the best performance of adsorbents examined. Data from the liquid ? phase experiments were fitted to the Chakravarti ? Dhar isotherm equation. From the vapor ? phase experiments, the average water loading of hardwood sawdust, kenaf core, and bleached wood pulp was 0.0037, 0.0076, and 0.0121 g H2O/g adsorbent, respectively. Two methods, the Colburn J Factor and the Thoenes ? Kramers correlation, were used to evaluate the mass transfer coefficient of water. Furthermore, the surface area of the adsorbents was measured using the B.E.T. method. Surface areas were 4.91, 9.99, and 8.84 m2/g for the hardwood sawdust, kenaf core, and the bleached wood pulp, respectively.

Increased levels of carbon dioxide in the atmosphere are now widely attributed as a leading cause for global climate change. As such, research efforts into the capture and sequestration of CO2 from large point sources (flue gas capture) as well as the ambient atmosphere (air capture) are gaining increased popularity and importance. Supported amine materials have emerged as a promising class of materials for these applications. However, more fundamental research is needed before these materials can be used in a practically relevant process. The following areas are considered critical research needs for these materials: (i) process design, (ii) material stability, (iii) kinetics of adsorption and desorption, (iv) improved sorbent adsorption efficiency and (v) understanding the effects of water on sorbent adsorption behavior. The aim of the studies presented in this thesis is to further the scientific community’s understanding of supported amine adsorbents with respect to stability, adsorption efficiency and adsorption behavior with water.

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The purpose of this thesis study is to assess the feasibility of using a fiber sorbent module system to remove t-butyl mercaptan (TBM), a common odorant, from pipeline grade natural gas. Odorants such as mercaptans are added to natural gas for safety reasons, but their combustion products are corrosive and decrease the lifetime of the turbines in which they are combusted. Therefore, it is desirable to remove the odorants to extend this lifetime. A TBM removal system attached to a 840 MW natural gas-fueled combined cycle power plant unit such as the one at Plant McDonough-Atkinson (Smyrna, GA) must process gas at a flow rate of approximately 180,000 standard cubic feet per minute. A single 85 MW GE 7EAQ gas turbine has a flow rate of approximately 15,000 standard cubic feet per minute, and will serve as the basis for a system design and process analysis study. The concentration of odorants in natural gas is typically 10 ppm or less. For the purposes of this study, the upper limit of 10 ppm TBM will be used. Zeolite 13X was selected as the model adsorbent for this study due to its high sorption capacity for mercaptans and its ease of incorporation into both fibers and pellets. Design calculations were performed to optimize and determine the feasibility of fiber modules for TBM removal, as well as assess their advantages over conventional pellet packed beds. An understanding of how critical parameters such as heat and mass transfer resistances, pressure drop, and capital and operating costs are affected by design specifications such as sorbent and bed dimensions, allows an optimal design for the needs of the model turbine to be found. Based on these design equations, a fiber sorbent module configuration that selectively and continuously removes TBM from natural gas is developed

Granular Activated Carbon (GAC) is used in packed beds to treat trace quantities of icropollutants. Many years of research and industrial use has ensured that it is highly effective as a water treatment process. However, GAC is expensive and economic considerations mean it has to be recovered and re-used Powdered Activated Carbon (PAC; is a cheaper alternative but the particle size range means it is unsuitable for packed bed applications. This thesis describes a novel method for utilising PAC to treat micropollutants. By contacting carbon paracles with air bubbles, under conditions o.lrotational shear and a binding agent, oleyl alcohol, carbon-coated air bubbles form which remain stable while agitated byflowing water. A stabilised air bubble can be visualised as a phere with an impervious core (the air bubble), surrounded by a thin layer of porous matehal (PAC). Theory dictates that all these stabilised air bubbles can be moved counter-currently to a contaminated stream, higher throughputs than conventional packed beds are possible. Several aspects of this process are investigated. Bubble generation is critical and so the literature was reviewed to explain the mechanisms involved Practical use was made of this knowledge in designing a larger bubble generator. Transferring the coated-bubbles to a contacting column was difficult. Problems associated with the various methods employed are described and recommendations are made for improvement. The contacting column was used to assess the stability and adsorptive capacity of the bubbles. The possibility of counter-current flow using stabilised air bubbles was also evaluated and found to be incompatible with the current column design. The stabilised bubbles collected in the column resembled an inverted fluidised bed. Experiments were performed to test Richardson and Zaki's hydrodynamic laws for conventional fluidised beds were applicable to inverted beds. The adsorptive capacity of the bubbles was assessed by dosing the water with trace levels of phenol and p-chlorophenol. Samples taken from before and after the fluidised bed were analysed and compared. The results were inconclusive, although the concentration profile produced indicated that flow through the bubble bed was piston-flow.

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The process of purifying hydrogen gas using pressure swing adsorption columns heavily relies on highly efficient adsorbents. Such materials must be able to selectively adsorb a large amount of impurities, and must also be regenerated with ease. The work presented in this thesis focuses on a novel class of porous solids, metal-organic frameworks (MOFs), and their potential for use as adsorbents in hydrogen purification processes. MOFs are tuneable structures, a property that can be exploited in order to achieve the desired characteristics that are beneficial for a specific application. The design or selection of MOFs for any separation process however, relies on a thorough understanding of the relationship between a framework’s characteristics and its adsorption and selective properties. In order to identify favourable MOF characteristics for the separation of hydrogen from typical impurities a systematic molecular simulation study is performed on a large group of MOFs. Features such as the presence of short linkers, amine groups and additional aromatic rings, and a high density of linker groups are found to increase the adsorbate - framework interaction strength, and reduce the free volume available inside the pores. Both of these effects are shown to enhance MOF selectivity for impurities. Two promising materials, exhibiting desirable features, Mn MIL-53 and MIL-47, are studied further through a variety of approaches. A combination of experimental work and molecular simulations are employed in order to assess the level of flexibility in Mn MIL-53 on uptake of CO2 and CH4. An investigation of the experimental and simulation adsorption and characterization data indicates that the framework undergoes structural changes, in order to accommodate CO2 molecules, but not CH4. The form of the framework during CO2 uptake is also shown to be strongly influenced by temperature. In the case of MIL-47, adsorption isotherms simulated for a wide range of gases overpredict experimental adsorption data, leading to an in-depth investigation of non-porous effects, force field suitability, and framework rigidity. Ab initio molecular dynamics studies of MIL-47 indicate that the benzene dicarboxylate linkers rotate about their symmetry axis to reach more energetically favourable configurations, an effect responsible for the discrepancies between simulated and experimental isotherms. The effect of MOF flexibility on adsorption is further highlighted in a study of Sc2BDC3, a material able to undergo structural changes in order to accommodate a variety of adsorbates. Molecular simulations show that structural changes in the framework are responsible for the creation of additional CO2 adsorption sites as pressure is increased, whereas methanol adsorption sites occupied at extreme pressure are stabilized by the formation of hydrogen bonds. Finally, the exceptionally robust UiO-66(Zr) and UiO-67(Zr) families of MOFs are analysed using a multi-scale simulation study combining molecular level and process-scale computational work, seeking to compare the materials to commercial adsorbents, and assess whether they are suitable for H2 purification through pressure swing adsorption (PSA). Of the four MOFs studied, UiO-66(Zr)-Br is the most promising, as it significantly outperforms commercial zeolites and activated carbons in H2 purification from steam methane reformer offgas.

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