Master of Science in Chemistry, Youngstown State University, 2019, Department of Chemistry

1,3–bis(2,4,6–trimethylphenyl)imidazolium carboxylate, an adduct between CO2 and the N–heterocyclic carbene (NHC), 1,3–bis(2,4,6–trimethylphenyl)–1,3–dihydro–2H–imidazol–2–ylidene, was synthesized to study the reactivity of CO2 after binding to the carbene intermediate. Nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, X–ray powder diffraction (XRD), gas chromatography (GC) and thermal gravimetric analysis (TGA) were employed to characterize the final imidazolium carboxylate. GC was specifically used to study the dissociation of the CO2 adduct. The structure of the synthesized zwitterion was confirmed via 1H and 13C NMR, where adduct formation generated a new peak in the 13C NMR spectrum. IR spectroscopic data showed a significant characteristic peak for C=O stretch at around 1670 cm–1. TGA spectra showed that the zwitterion‟s weight loss of 13% at 155 °C which is the percent weight of CO2 . The GC study of CO2 , which was released after treating the imidazolium carboxylate with 5% H2O in CH3CN, enabled the possibility of the reversibility of CO2– NHC adduct formation. The stability and air sensitivity of the imidazolium carboxylate were tested in polar, nonpolar, acidic, basic, and mixed solvents via simple effervescence tests and GC. The hydrolytic stability of the imidazolium carboxylate was examined. The bis-mesityl carboxylate showed reasonable stability in water, in contrast to carboxylates with smaller alkyl substituents, but admixture with organic solvent would cause it to break down into the corresponding imidazolium bicarbonate. After exposure to H2 (g) and heat, there was evidence for the reductive conversion of the carboxylate into imidazolium formate. This suggests the application of the mesityl imidazolyl carbene as an organic catalyst for CO2 reduction.

Committee: Linkous Clovis PhD (Advisor); Jackson John PhD (Committee Member); Serra Michael PhD (Committee Member) Subjects: Analytical Chemistry; Chemistry; Climate Change

Doctor of Philosophy (PhD), Ohio University, 2013, Mechanical Engineering (Engineering and Technology)

Inorganic carbon behavior was measured and modeled to identify a transitional gas phase CO2 concentration for thermophilic cyanobacterial growth in a membrane-based photobioreactor. It was hypothesized that for a given growth system at optimal productivity, there is a gas phase CO2 concentration that will supply necessary inorganic carbon at a rate that matches the photosynthetic demand. Identifying this gas phase concentration is complicated by the chemical composition of the growth media, the mass transfer characteristics of the gas-liquid interface, and the speciation of inorganic carbon that is preferred for the carbon concentration mechanism of the photosynthetic organism. An empirical model of inorganic carbon behavior was developed to more fully understand the behavior of the system and help identify the transitional CO2 concentration. In this research, total inorganic carbon (TIC) concentrations resulting from CO2 absorption in various liquid media were measured, along with changes in pH, using air (380 ppm CO2), 0.1%, 0.5%, 1.0%, 1.5%, 2.0% and 10% CO2 under atmospheric pressure at temperatures of 25, 35, 45, and 55°C. Inorganic carbon behavior was quantified, including the saturation conditions and CO2 mass transfer rates. The rate of change of TIC prior to saturation was used to determine pseudo-CO2 mass transfer coefficients. An empirical model for the CO2 mass transfer was developed to predict inorganic carbon concentrations. The TIC results from the empirical model were validated with experiments. The results indicated that activity coefficients play a much more important role in vapor-liquid equilibrium than fugacity coefficients. Ambient air and CO2 concentrations of 0.1% and 2.0% were used to examine cyanobacteria growth with respect to changes in CO2 levels. TIC, media pH corresponding to fluctuation of TIC, biomass productivity and total dissolved solid (TDS) were used to specify a transitional CO2 concentration. The results of inorga (open full item for complete abstract)

Committee: Bayless David (Committee Co-Chair); Stuart Ben (Committee Co-Chair); Riefler Guy (Committee Member); Vis-Chiasson Morgan (Committee Member); Rose-Grippa Kathaleen (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2010, Chemical Engineering

Supercritical (high pressure) CO2, owing to its ability to make polymers pliable at temperatures much lower than the glass transition temperature (Tg), has been established as a very promising solvent for numerous macro scale polymer processing applications. In this work, we have tried to expand the scope of supercritical CO2 assisted polymer processing to nano length scales with particular focus on manufacturing biomedical devices from polymer thin films. At such small length scales, however, the properties of the polymer become size dependent since the interfacial effects start dominating the bulk effects. As a result, adapting the macro and micro level fabrication technologies to nano level is not straightforward and requires integration of both theoretical and experimental tools. We have used CO2 assisted Nano-Imprint Lithography (CO2-NIL) for fabricating nanochannels on polystyrene thin films. CO2-NIL is a novel technique in which the features from a rigid mold are transferred on to a CO2 pressurized polymer thin film by application of compressive force. We have explored efficiency of pattern transfer, resolution, and effects of molecular weight on transferability of patterns, and have thus established CO2-NIL as a highly efficient and cost effective fabrication technique capable of transferring patterns as small as 20 nm in step height. To understand the surface characteristics and the molecular level effects of CO2 on polymer thin films, which are essential for optimizing the nanoscale experiments, we have used Polymer Density Functional Theory (PDFT) as our primary tool since it provides an adequate balance between the amount of details extracted and the computational costs involved. PDFT is a statistical mechanics based approach in which we express the free energy of the system as a functional of spatially varying density distributions of CO2 and polymer segments. Equilibrium density distributions, free energy at equilibrium, and hence the equilibrium pr (open full item for complete abstract)

Committee: Isamu Kusaka PhD (Advisor); David L. Tomasko PhD (Committee Member); L. James Lee PhD (Committee Member); Susan Olesik PhD (Committee Member) Subjects: Chemical Engineering

Master of Science in Chemistry, Youngstown State University, 2019, Department of Chemistry

N-Heterocyclic carbenes have been recognized for their ability to capture CO2 at standard temperature and pressure. This makes them a molecule that could be used for renewable energy synthetic methods. Synthesis and characterization of an IMesCO2 derivative based on bis-mesityl imidazolium chloride was performed, followed by one of four commonly used reduction methods. Methanol is a possible product from a successful reduction through hydrogenation. Efficient production of this species could establish CO2 as a viable renewable energy source. A high pressure hydrogen gas experiment as well as three possible hydride reduction pathways were investigated. Hydrogen gas was used to beak the C2-carbon dioxide bond. This technique explores the results of introducing the IMesCO2 to a neutral hydrogen, which resulted in the formation of formic acid. Hydride reductions were done with lithium aluminum hydride, lithium borohydride and sodium borohydride. They were introduced to the IMesCO2 to donate a hydride to the C2-carbon dioxide bond. The different hydrides varied in selectivity toward IMesCO2 reduction. IMesCO2, possessing a carbonyl group, was subjected to all the hydrides in appropriate solvents. Therefore, the reaction showed the formation of formate for several scenarios. The key to these reductions was the solvent: tetrahydrofuran in conjunction with lithium aluminum hydride; tetrahydrofuran, acetonitrile, and dimethyl sulfoxide used with lithium borohydride; and tetrahydrofuran, acetonitrile, and dimethyl sulfoxide with sodium borohydride. However, there seemed to be a need for a balance between reducing strength of the hydride and selectivity for the carbonyl. To further expand on the idea of using appropriate solvents, sodium tetraphenyl borate was included as an additive to promote reduction via increased solubility, but reactivity with the sodium borohydride did not generally increase. Furthermore, several reaction spectra show evidence of the imidazol (open full item for complete abstract)

Committee: Clovis Linkous PhD (Advisor); Brian Leskiw PhD (Committee Member); Douglas Genna PhD (Committee Member) Subjects: Chemistry

Doctor of Philosophy, University of Akron, 2018, Polymer Science

Fossil energy from coal, gas, and oil-based fuel stocks remains a vital cornerstone of the global energy infrastructure while contributing over half of annual CO2 emissions. Rising global CO2 concentrations and aberrant trends in climate have sparked recent scrutiny of the energy industry sustainability. Carbon capture, utilization, and storage (CCUS) at the site of power plants has been proposed as a strategy for mitigating atmospheric CO2. This dissertation covers simulated and experimental models designed to address key problems in both the fundamental science and applied engineering of amine-functionalized silica sorbents for carbon capture from few molecule DFT (density functional theory) calculation to kilogram-scale technology validation. DFT was used to emulate small molecule and polymeric amines with good agreement in four successive series of models. (i) The concept of CO2 adsorption strength on secondary amines was investigated which revealed lone amine sites produce weakly adsorbed species while dense amine pairs yield strongly adsorbed species. (ii) Mixed amine types are common in blended or polymeric amine systems and convolute data interpretation. The hydrogen bonding ability of ammonium carbamate pairs demonstrated significant dependence on amine type and local hydrogen bond partners. (iii) Fixation of amines onto substrates is a ubiquitous strategy for preparing CO2 sorbents. The effect of geometric constraint imposed by immobilization was investigated for simulated propylamine pairs. Binding energy was linearly dependent on the alignment of ammonium carbamate. FTIR features were categorized into four groups. (iv) Selective formation of carbamic acid was studied by modeling reactants, intermediates, transition states (TS), and products of the amine-CO2 reaction on simulated diamine substrates. It was shown that significant reduction in TS activation energy occurred by Grotthus-like proton hopping. Coal-fire power plant CO2 capture was experime (open full item for complete abstract)

Committee: Steven Chuang (Advisor); Mesfin Tsige (Committee Chair); Tianbo Liu (Committee Member); Stephen Cheng (Committee Member); David Perry (Committee Member) Subjects: Chemical Engineering; Chemistry; Materials Science; Physical Chemistry; Polymers

Doctor of Philosophy, The Ohio State University, 2018, Chemistry

The upsurge in anthropogenic activities since the Industrial Revolution has led to an increase in atmospheric carbon dioxide (CO2) concentration that is a significant factor in global climate change. Attempts to curtail a further rise in atmospheric CO2 concentration include technology that captures and sequesters CO2 from local point sources where it is being emitted and/or capture and conversion technologies that transforms CO2 to other chemicals that can be used as raw materials, such that no additional consumption of fossil fuels is need to create these raw materials. Currently, there are no large commercial processes that convert CO2 to useful chemicals, save for the water-gas shift that leads to the Fischer-Tropsch process, but both of these reactions require a large amount of energy input. Simpler methods exist, such as the electrochemical conversion of CO2, which can be performed in aqueous solution at room temperature and atmospheric pressure. This CO2 utilization pathway, however, is not yet fully developed for several reasons: lack of a selective and robust catalyst, large energy input required for desirable products, and low rate of reaction. The electrochemical CO2 reduction reaction (CO2RR) has been widely studied in recent years but is still in its infancy. This work addresses various challenges faced in the design of selective and active catalyst materials while also focusing on experimental design and providing insights into the CO2RR mechanism. Due to copper's (Cu) unique ability to convert CO2 to hydrocarbons and alcohols, Cu-based materials are of prime interest. Planar Cu foils served as a model catalyst for experimental parameter studies in this work, in which we found that gas and solution flow rates, as well as electrochemical cell design, play a crucial role in controlling the selectivity of the reaction. Cu foils were also used as a model in isotopic labelling experiments that provide insights into the CO¬2RR mechanism, such that (open full item for complete abstract)

Committee: Co Anne (Advisor); Olesik Susan (Committee Member); Wu Yiying (Committee Member); Lal Rattan (Committee Member) Subjects: Chemistry; Energy; Materials Science

Doctor of Philosophy, The Ohio State University, 2018, Chemical Engineering

Membrane processes are attractive for gas separation applications, including H2 purification and CO2 capture. Advanced nanostructured polymer membranes based on facilitated transport mechanism showed potential in H2 purification for fuel cell applications due to its oxidative stability and ability to simultaneously remove CO2 and H2S from a feed gas. In addition, the membranes could achieve high CO2 permeance and hence also suitable for CO2 capture from flue gas. In this work, CO2-selective membranes research development from lab-scale to field-test was conducted. CO2-selective membranes comprised of a quaternaryammonium hydroxide mobile carrier, a quaternary ammonium fluoride fixed-site carrier, borate-based additives, and crosslinked polyvinylalcohol was developed. The optimized membrane composition containing tetrafluoroboric acid demonstrated oxidative stability with a CO2 permeance of 100 GPU and CO2/H2 selectivity > 100 for at least 144 hours at 120°C with humid air as the sweep gas. The membrane was scaled-up to fabricate 14-in wide flat sheet membranes with > 1400-ft long in total length. The scale-up membrane performed similarly compared to the lab-scale membranes and demonstrated the potential for membrane processes that use air as the sweep gas including the H2 purification in fuel cell applications. Fabrication of CO2-selective membranes was scaled-up to prepare membranes with 14-in wide and > 150-ft long with a uniform selective-layer thickness of around 15 microns. The membrane contained aminoisobutyric potassium salt and polyvinylamine as the carriers for facilitated transport of acid gases and crosslinked polyvinylalcohol as the membrane matrix. The scale-up membranes demonstrated similar performances as the lab-scale membranes with a CO2 permeance > 200 GPU, CO2/H2 selectivity > 200, and H2S/H2 selectivity > 600 and were used for a field test of prototype spiral-wound membrane modules with autothermal reformate gas as the feed gas. The modeling (open full item for complete abstract)

Committee: W.S. Winston Ho (Advisor); Bhavik Bakshi (Committee Member); NIcholas Brunelli (Committee Member) Subjects: Chemical Engineering

Master of Science (MS), Ohio University, 2017, Chemical Engineering (Engineering and Technology)

The use of monoethylene glycol (MEG) is common in the oil and gas industry as it is injected in subsea flowlines to prevent hydrate formation. Albeit this is one of the main uses for this chemical in this industry, previous studies have indicated that the presence of MEG reduces the extent of corrosion of mild steel in CO2 and H2S dominated environments. Furthermore, MEG is reported to serve as a key component of pH-stabilization technique used for corrosion mitigation. Experimental work published over the last few years has provided valuable insight on the possible overall effect of MEG on uniform corrosion rates, however, wide gaps still remain especially related to mechanistic representation of the phenomenon involved. In this work, a systematic electrochemical study was performed on the effect of MEG on CO2 corrosion mechanisms of mild steel, in particular API 5L X65 (0.16wt. % Carbon). The scope of work covered the influence of temperature from 30 – 80ºC, of MEG content from 40 – 85wt. % and of pH 3.5 - 6 at atmospheric pressure for solutions saturated with CO2 and N2, respectively. Electrochemical techniques such as linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and potentiodynamic sweeps were used to obtain corrosion rates, mixed potential (Ecorr), current density (Icorr), Tafel slopes and limiting currents. The experiments were performed in a typical three electrode set-up where a Rotating Cylinder Electrode (RCE) was used to study the effect of flow at rotation speeds of 100, 1000 and 2000RPM (equivalent to 0.2, 1.2 and 2.0m/s, respectively in a 4in pipeline). The completion of these experiments revealed that MEG reduces the corrosion rate by affecting in different ways both anodic and cathodic electrochemical reactions involved in CO2 corrosion mechanisms. By performing potentiodynamic sweeps, it was noted that the dissolution of iron was retarded with increasing glycol content in solution, inferring that MEG may adsorb (open full item for complete abstract)

Committee: Marc Singer (Advisor); Bruce Brown (Other); Srdjan Nesic (Committee Member); John Staser (Committee Member); Rebecca Barlag (Committee Member) Subjects: Chemical Engineering; Engineering; Petroleum Engineering

Master of Science, The Ohio State University, 2017, Civil Engineering

The sustained release of greenhouse gases (GHGs) into the atmosphere is increasing global average temperatures and resulting in changes to the global climate. These changes can result in human and economic harm prompting increased research into the mitigation of GHGs specifically carbon dioxide (CO2) emissions. Carbon dioxide (CO2) capture and storage (CCS) technology may reduce CO2 emissions by injecting CO2 captured from large point sources (e.g., coal-fired power plants) into deep geologic formations for storage. The added mass of CO2 typically increases reservoir pressure, which increases operational costs and risks linked to overpressure such as wellbore leakage, caprock fracture, and induced seismicity. The simultaneous extraction of brine during CO2 injection can actively manage the reservoir pressure, reduce risks linked to overpressure, increase the reliable CO2 storage capacity, redesign the CO2 plume monitoring area, and potentially provide a new water source. This process is also known as CO2 Enhanced Water Recovery (CO2-EWR). CO2-EWR is modeled by integrating the Finite Element Heat and Mass Transfer code (fehm.lanl.gov) to simulate the flow of CO2 and brine within the reservoir and a well model to connect the properties of CO2 and brine at the surface to the properties in the reservoir. The integrated consideration of the two models determines optimal combinations of CO2 injection and brine extraction rates and identifies relationships dictated by the injection and storage of CO2 and brine extraction. I modeled CO2-EWR in the Rock Springs Uplift (RSU) formation in southwest Wyoming and controlled the rates of CO2 injection and brine extraction in order to understand the physical tradeoffs that affect the pressure evolution, CO2 storage capabilities, and CO2 Area of Review (AoR) in the aquifer. Results indicated that the implementation of brine extraction can reduce the reservoir pressure and potentially facilitate increased capacity of CO2 stor (open full item for complete abstract)

Committee: Jeffrey M. Bielicki (Advisor); Gil Bohrer (Committee Member); Linda Weavers (Committee Member) Subjects: Civil Engineering; Climate Change; Environmental Engineering; Sustainability

Doctor of Philosophy, University of Akron, 2016, Polymer Science

Clean energy and environment is a 21st-century contemporary challenge we human being faces. Tremendous effort has been paid to explore and develop technologies to produce green energy, to reduce the emissions of wastes, and to utilize these wastes and renewable sources. Catalysis technologies and CO2 capture and utilization technologies are among the most important stepping stones to achieve the challenging goals to secure the environment for human survival and development. The advancement in these technologies requires a molecular-level or quantum-level fundamental understanding of the processes involved. One critical aspect of importance is the nature of the adsorbed species and their evolution in these green chemical processes. Fourier transform infrared (FTIR) spectroscopy is a powerful and versatile tool that can provide the insights to address these scientific issues. This dissertation, with a focus on the applications of in-situ FTIR spectroscopy, discusses about a few important topics in CO2 capture and other green processes, including (i) the catalytic asymmetric hydrogenation of a-amino ester, a potential chemical building block and starting material for biocompatible polymers, (ii) the oxidative and CO2-induced degradation of supported polyethylenimine (PEI) adsorbents for CO2 capture, (iii) the utilization of CO2 by the catalytic conversion of CO2 to carbonates, a precursor for polycarbonates and polyurethanes, (iv) the catalytic conversion of 2,3-butanediol to 1,3-butadiene, the monomer for synthetic rubbers, and (v) the electron-induced IR absorbance in photocatalytic processes on TiO2. A wide array of FTIR techniques, including diffuse reflectance, attenuated total reflectance, and transmission IR has been applied. The FTIR results revealed the vital hydrogen bonding interactions in the catalytic asymmetric hydrogenation of a-amino ester which led to the prochiral structures. The oxidative degradation and CO2-induced degradation pathways were (open full item for complete abstract)

Committee: Steven Chuang Ph.D. (Advisor); Toshikazu Miyoshi Ph.D. (Committee Chair); Xiong Gong Ph.D. (Committee Member); William Landis Ph.D. (Committee Member); Mesfin Tsige Ph.D. (Committee Member) Subjects: Chemical Engineering; Energy; Engineering; Environmental Science; Polymers

Doctor of Philosophy, Case Western Reserve University, 2014, Chemical Engineering

A novel class of biobased cross-linked polymers combining the molecular structure of both chitosan (CTS) and polybenzoxazine (PBZ) is synthesized via blending in aqueous media. The benzoxazine precursors, main-chain type benzoxazine polymer and star-like telechelic benzoxazine, are synthesized through Mannich condensation reaction of phenols and primary amines, in the presence of either formaldehyde or paraformaldehyde. Synergistic improvements in the thermal and mechanical properties of biobased cross-linked polymers are observed due to presence of oxazine-ring which provides more crosslinking density. Furthermore, utilization of these newly developed crosslinked polymers in adsorption of CO2 has been investigated. Various nanocomposite aerogels have been fabricated using either sodium montmorillonite (Na-MMT) or graphene oxide (GO), and their carbon aerogels (CAs) show superior CO2 adsorption capacity. Firstly, new nanocomposite aerogels have been synthesized from clay-reinforced CTS/polybenzoxazine via freeze-drying. Scanning electron microscopy is used to verify that the addition of clay leads to layered structure in the hybrids. Carbonization of the developed aerogels was performed to increase the surface area and to enhance the structure of the aerogels. Combination of Na-MMT in the cross-linked polymers increases the CO2 adsorption capacity from 2.1 mmol g-1 to 5.7 mmol g-1, depending on the benzoxazine concentration. The Freundlich isotherm model provides a good fit of the adsorption data with hybrid aerogels. Secondly, CTS/GO monoliths show an increase in the adsorption capacity of CO2 from 1.92 to 3.48 mmol g-1 with 10 wt% GO at ambient conditions. Doubling the concentration of GO from 10 to 20 wt% increases the adsorption capacity only 20 %. To improve this system, hybridization of the two different cross-linked polymers with 10 wt% GO is applied to develop novel nanocomposite aerogels. Significant enhancements in the mechanical and thermal propertie (open full item for complete abstract)

Committee: Syed Qutubuddin Dr. (Advisor); Hatsuo Ishida Dr. (Advisor); Chung-Chiun Liu Dr. (Committee Member); R. Mohan Sankaran Dr. (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2012, Materials Science and Engineering

A new potentiometric CO2 gas sensor using lithium-lanthanum-titanate (Li0.35La0.55TiO3) electrolyte, Li2CO3 sensing electrode, and Li2TiO3+TiO2 reference electrode was investigated. The microstructure and electrical properties of the optimized solid electrolyte were examined and the measured conductivity values were found consistent with those reported in literature. The sensor was tested under dry condition in 21% O2/N2 at temperatures ranging from 250 to 550°C. As the temperature increased, the percentage of Nernstian behavior improved from 50% at 250°C to 95% at 450°C, but the performance degraded above 450°C. The proposed hypothesis for the degradation is as follows. Depending on CO2 partial pressure, Li2CO3 can decompose and react with Li0.35La0.55TiO3 around 475-500°C resulting in insertion of Li+ into Li0.35La0.55TiO3 that causes structural distortion. When the reaction between Li2CO3 and Li0.35La0.55TiO3 occurs at elevated temperatures such as at 700°C, the distorted structure transforms to disordered LaLi1/3Ti2/3O3 and the sensor performance degrades irreversibly. Thermodynamic calculations combined with solid-state reaction under controlled atmosphere followed by X-ray diffraction (XRD) are used to confirm the hypothesis. Finally, for device fabrication, it is demonstrated that introduction of high concentration of CO2 (~99.99%) can avoid the reaction between Li2CO3 and Li0.35La0.55TiO3 at high temperatures, which also facilitates good bonding between the electrode and the electrolyte. As for long-term device performance, it is shown that the sensor can measure changes in CO2 concentrations reproducibly as long as it is operated in conditions where there is a background of CO2, such as in ambient atmosphere or combustion systems.

Committee: Sheikh Akbar Prof/PhD (Advisor); Prabir Dutta Prof/PhD (Advisor); Gerald Frankel Prof/PhD (Committee Member); Patricia Morris Prof/PhD (Committee Member) Subjects: Materials Science

Master of Science (MS), Ohio University, 2013, Chemical Engineering (Engineering and Technology)

Due to the isostructurality between calcite (CaCO3) and siderite (FeCO3), the Ca2+ ion incorporates in the hexagonal FeCO3 lattice and vice versa the Fe2+ ion incorporates in the hexagonal CaCO3 lattice. Thus, in aqueous CO2 environments, where both Ca2+ and Fe2+ are present, such as in gas reservoirs or deep saline aquifers, following CO2 injection, mixed metal carbonates with the formula FexCayCO3 (x+y=1) will be expected to form. This will likely have implications for corrosion, so that corrosion product layers will have the potential to be inhomogeneous, with behavior that deviates from that of pure FeCO3. In the present study, the effect of Ca2+ on the CO2 corrosion behavior of mild steel was investigated with different concentrations of Ca2+ (10, 100, 1,000 and 10,000 ppm). Electrochemical methods (open circuit potential (OCP) and linear polarization resistance (LPR) measurements) were used to measure the corrosion rate with time. Surface analysis techniques (scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD)), were used to characterize the morphology and composition of the corrosion products. The results showed that with low concentrations of Ca2+ (10 and 100 ppm), the corrosion rate decreased with time due to the formation of protective FeCO3 and/or FexCayCO3 (x + y =1). However, the presence of high concentrations of Ca2+ (1,000 and 10,000 ppm) resulted in the change of corrosion product from protective FeCO3 to non-protective CaCO3 and FexCayCO3 (x + y =1) and an increasing corrosion rate with time. While the general corrosion rate was high for both 1,000 and 10,000 ppm Ca2+, surface analysis data revealed that localized corrosion was observed in the presence of 10,000 ppm Ca2+. Since Ca2+ was added in the tested conditions as CaCl2, the possible effect of Cl- on the non-uniform attack was studied by testing with the equivalent concentration of Cl- using a NaCl solution. However, the result showed (open full item for complete abstract)

Committee: Srdjan Nesic Prof. (Advisor) Subjects: Engineering

Doctor of Philosophy (PhD), Ohio University, 2013, Chemical Engineering (Engineering and Technology)

The need to develop natural gas hydrocarbon gas fields that have high concentrations of CO2 necessitates technical evaluation of the feasibility of using carbon steels as infrastructure material particularly as its use would positively impact the economic viability of such development projects. This requires a suitable CO2 corrosion prediction model. However, the upper pressure limit of existing CO2 corrosion prediction models is 20 bar, well below the encountered subcritical and supercritical pressures (73.4 bar). Employing existing models for the design of the production assets would lead to over prediction, resulting in over design and high costs. A further requirement for the development of a suitable corrosion model for high CO2 partial pressure environments was the inclusion of the effect of flow. Therefore, this study focused on three parameters that might affect the flow-sensitivity of CO2 corrosion: CO2 partial pressure, pH, and temperature. To accomplish the objectives, two types of flow geometries were used to study flow-sensitive corrosion at elevated CO2 partial pressure and high temperature environment: rotating cylinder electrode (RCE) and thin-channel flow cell (TCFC). Since TCFC was a new flow apparatus, the mass transfer behavior of TCFC was characterized using limiting current density technique. In the experiment, the limiting current density of API 5L X-65 carbon steel was measured at various velocities in 1 wt% NaCl electrolyte at pH 3.0 for each of the test temperatures of 30o C and 50o C. The data showed good correlation with the mass transfer correlation of Sleicher and Rouse for a smooth pipeline. This established TCFC as being suitable for study of flow-sensitive corrosion. In RCE experiments, the effect of pH (pH 3.0 to pH 5.0) was studied at CO2 partial pressure of 10 bar and temperature of 25o C and 50o C in 1 wt% NaCl electrolyte. The findings indicated that the increase in pH led to the decrease in corrosion rate. Mos (open full item for complete abstract)

Committee: Srdjan Nesic Prof. (Advisor); Howard Dewald Prof. (Committee Member); Jeffrey Rack Prof. (Committee Member); Dusan Sormaz Assoc. Prof. (Committee Member); David Young Dr (Committee Member) Subjects: Chemical Engineering

PhD, University of Cincinnati, 2024, Engineering and Applied Science: Aerospace Engineering

The move towards renewable energy has highlighted the need for large-scale, environmentally friendly energy storage solutions. Among these, the Supercritical Carbon Dioxide (sCO2) power cycle is emerging as a promising technology for advanced energy conversion. The effectiveness of such systems depends heavily on the compressor's performance. Using optimization-based methods, a multistage axial compressor has been designed, and its first stage has been built and tested experimentally. Through a series of detailed design iterations and optimization strategies, 3D CFD analyses, the compressor's geometric and operational parameters were fine-tuned to address the unique challenges posed by operation using CO2. Key findings highlight the successful implementation of design optimization that significantly reduces aerodynamic losses and improves the overall efficiency of the compressor stages. The optimized compressor demonstrates robust performance across a range of operating conditions, particularly focusing on improved stall margin, which emphasizes the potential of sCO2 technology in contributing to efficient and sustainable energy systems. Further detailed studies using CFD to analyze cavity effects in shrouded configurations, tip clearance effects, real gas effects, and Reynolds number effects were performed. Experimental validations, conducted at the University of Notre Dame Turbomachinery Laboratory, confirm the CFD predictions and showcase the practical viability of the compressor design and the approach used. This work not only advances the state-of-the-art in turbomachinery design for supercritical fluids but also lays a foundation for future research into the integration of sCO2 and real gas based compressors in renewable energy systems and industrial applications. The insights gained from this study underscore the critical importance of tailored design and optimization strategies in overcoming the thermophysical challenges associated (open full item for complete abstract)

Committee: Mark Turner Sc.D. (Committee Chair); Daniel Cuppoletti Ph.D. (Committee Member); Kelly Cohen Ph.D. (Committee Member); Jeong-Seek Kang Ph.D. (Committee Member); Shaaban Abdallah Ph.D. (Committee Member) Subjects: Aerospace Engineering

Doctor of Philosophy, Case Western Reserve University, 2025, Chemical Engineering

Direct air capture (DAC) of CO2 is a keystone technology in global plans to mitigate climate change. While the existing materials capable of performing this difficult separation can absorb high amounts of CO2 from air, the heat required to regenerate them for reuse imposes an immense energy tax. With projected energy demands for DAC exceeding 120 petajoules per year by 2030 (nearly the total annual electricity consumption of Ireland), more efficient materials and processes are vital to reaching net zero CO2 emissions. Ionic liquids (ILs) – salts that melt below 100 ˚C – are a class of solvents with exceptional tunability and negligible volatility, making them excellent candidate materials for DAC. However, a major barrier to the implementation of ILs in DAC is their high viscosity, limiting the diffusion rate of CO2. Through fundamental property characterization, spectroscopic investigation, and lab-scale performance analysis, this thesis seeks to build the scientific foundation for leveraging the advantages of ILs while mitigating their weaknesses by creating composite materials with ILs, enabling high performance DAC sorbents that can be regenerated using dielectric heating (the same heating mechanism as a kitchen microwave). We first explore the complex role that hydrogen bonding plays in CO2 binding mechanisms when diluting amino acid ILs with ethylene glycol to lower their viscosity. We reveal through collaborative study with computational chemists that hydrogen bonding can limit the interactions between amine binding sites, preventing their deactivation and resulting in maintained gravimetric capacity upon dilution. Next, we demonstrate the first successful regeneration of an IL by microwave irradiation. We reveal through finite element modeling that experimental trends in heating rate when varying frequency and material are highly dependent on the geometry of the system. Finally, we investigate the formation of composites between an IL and a metal organic (open full item for complete abstract)

Committee: Burcu Gurkan (Advisor); Christine Duval (Committee Member); Michelle Kidder (Committee Member); Pavel Fileviez-Perez (Committee Member); Rohan Akolkar (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Oil and gas transmission pipelines are frequently prone to internal corrosion in field environments. Use of organic corrosion inhibitors is an economical and effective way to combat this problem. Their typically amphiphilic inhibitor molecules provide protection by adsorption on the metal surface. Therefore, understanding and quantifying adsorption phenomena has significance for prediction of corrosion inhibition performance of a particular compound. In this dissertation research, a quartz crystal microbalance with dissipation monitoring (QCM-D) was the primary tool used to investigate the adsorption of two corrosion inhibitor model compounds on a noble gold substrate. The research reported herein shows how QCM-D can be used effectively to gain insights about the properties of the adsorbed layer, quantify adsorption/desorption kinetics, make predictions on the possible adsorbed layer configurations, and investigate the influence of inhibitor molecular structure on adsorption phenomena. Since real scenarios involve an actively corroding substrate, a classical oscillatory circuit-based quartz crystal microbalance (QCM) was also used to probe the metal-solution interface for a corroding and corrosion product forming experimental system; this facilitated deciphering the various reaction steps involved. The QCM-D findings in the present research indicate that the geometric surface coverage was less than 100% even for inhibitor concentrations above the surface saturation concentrations. This can help in answering a historical question in corrosion inhibition research about non-zero corrosion rates at inhibitor concentrations corresponding to maximum inhibition. Furthermore, the kinetic adsorption/desorption constants were estimated from the adsorption curves and verified successfully by predicting desorption behavior. This is of great significance, as this methodology can be further extended to study corrosion inhibition and its persistency. Furthermore, this serves as (open full item for complete abstract)

Committee: Srdjan Nešić (Advisor) Subjects: Chemical Engineering

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Carbon steel pipelines in the oil and gas industry are susceptible to corrosion due to their exposure to corrosive gases like carbon dioxide (CO2) dissolved in the reservoir brine. These pipelines typically carry a mixture of oil, water, and gas phases. The oil phase does not cause corrosion – only the wetting of the pipe surface by water does. However, the alternating wetting of the pipeline surface by oil and water, known as "oil/water intermittent wetting", can influence the corrosion mechanisms and make the surface more resistant to corrosion even if it returns to a fully water wet state. Although extensive research has been conducted on CO2 corrosion in water-only environments, the role of the oil phase has often been far less investigated. Existing literature on the effects of oil are limited to flow patterns and phase wetting studies, with no direct correlation to corrosion rates. This study aims to develop an experimental apparatus and methodology that simulates oil/water intermittent wetting and investigate its effect on uniform and localized CO2 corrosion behavior of carbon steel. A wide range of experimental conditions, including different types of model oils containing surface-active compounds with varying concentrations, different pH values, flow velocities, elevated temperatures, and longer exposure time to oil/water intermittent wetting, were tested.

Committee: Marc Singer (Advisor); Srdjan Nesic (Committee Member); Jixin Chen (Committee Member); Bruce Brown (Committee Member); Mark McMills (Committee Member); David Young (Committee Member) Subjects: Chemical Engineering; Chemistry; Energy; Sustainability

PhD, University of Cincinnati, 2024, Arts and Sciences: Chemistry

Electrosynthesis is a popular and green alternative to traditional organic methods for synthesizing small organic molecules. Due to its ability to generate highly reactive species under mild conditions by anodic oxidation or cathodic reduction, electrosynthesis is particularly interesting for otherwise challenging transformations. The contents of this dissertation are primarily focused on the evaluation of molecular electrocatalysts and their role in small molecule activation such as carbon dioxide (CO2) reduction and dehalogenation reactions. The electrochemical reduction of CO2 to produce value-added chemicals is of great significance in mitigating environmental and energy concerns. In this work, an iron porphyrin catalyst, FePEG8T, with multiple triazole units tethered to a porphyrin ligand via flexible oxymethylene linkers, is reported for efficient electrocatalytic reduction of CO2 to afford carbon monoxide (CO). The electrocatalyst exhibits excellent catalytic activity with a current density of –17.5 mA/cm2 and CO Faradaic efficiency of 95% at –2.5 V vs. Fc/Fc+ in acetonitrile using water as the proton source. The maximum turnover frequency (TOFmax) was calculated to be 5.5 x 104 s-1 using foot-of-the-wave analysis (FOWA), which is thirty times higher than the result from our previous zinc complex with the same triazole-porphyrin ligand. Long-term electrolysis of 40 hours was also performed and demonstrated high catalyst stability. Further, Tafel plot was generated for the catalyst FePEG8T for comparison with previously reported iron porphyrin catalysts. This work demonstrates an efficient CO2 reduction catalyst containing an iron metal center and a flexible triazole in the second coordination sphere toward CO formation with high stability, activity, and selectivity. Reductive hydrodechlorination is an effective approach to enhance the degradation rate of chlorinated herbicides such as alachlor, which are frequently detected in ground and surface (open full item for complete abstract)

Committee: Jianbing Jiang Ph.D. (Committee Chair); Noe Alvarez Ph.D. (Committee Member); Hairong Guan Ph.D. (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2024, Chemical Engineering

Humankind is constantly engaged in the pursuit of innovative approaches to improve process efficiency, economics, and safety. Chemical looping, a novel methodology involving a reaction carried out in multiple stages facilitated by a solid intermediate called a carrier, offers additional degrees of freedom for process intensification and product optimization. This dissertation involves the development and scale-up of new alternatives for several conventional catalytic processes, leveraging the benefits offered by the chemical looping platform to enhance operational flexibility, product yields, and process safety. The first part of this dissertation focuses on the development of alternative processes for the removal of two common industrial pollutants, NOx and H2S. NOx, a harmful pollutant generated during the processing of fossil fuels, is conventionally treated using the Selective Catalytic Reduction (SCR) process, which faces challenges such as high costs and limited operational flexibility. The chemical looping process achieves over 99% NOx removal efficiency, demonstrating significant improvements of 9% and 18% in exergy and effective thermal efficiency, respectively, over the state-of-the-art SCR process. H2S, another harmful pollutant generated during the processing of fossil fuels, is conventionally removed using the Claus Process, which encounters drawbacks such as thermodynamic limitations on conversion and the loss of valuable H2 in the form of H2O. This dissertation introduces a nano-scaled iron sulfide carrier, demonstrating ~70% enhancement in reactivity over traditional bulk carriers in chemical looping H2S splitting into H2 and sulfur. Furthermore, process analyses indicate an improvement of ~22 percentage points in energy and ~8 percentage points in exergy efficiency over the Claus process. The second part of this dissertation involves the development of new processes for commodity chemical production. Formaldehyde, an essential organic chemical wit (open full item for complete abstract)

Committee: Prof. Liang-Shih Fan (Advisor); Prof. Jeffrey Chalmers (Committee Member); Prof. Lisa Hall (Committee Member); Prof. Dawn Anderson-Butcher (Committee Member) Subjects: Chemical Engineering