Engineering Commons^™

Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera

Doctoral Dissertations

In this work, a systematic computational study directed toward developing a molecular-level understanding of gas adsorption and diffusion characteristics in nano-porous materials is presented. Two different types of porous adsorbents were studied, one crystalline and the other amorphous. Physisorption and diffusion of hydrogen in ten iso-reticular metal-organic frameworks (IRMOFs) were investigated. A set of nine adsorbents taken from a class of novel, amorphous nano-porous materials composed of spherosilicate building blocks and isolated metal sites was also studied, with attention paid to the adsorptive and diffusive behavior of hydrogen, methane, carbon dioxide and their binary mixtures. Both classes of materials were …

Membrane And Performance Study In Polymer Electrolyte Membrane Fuel Cells And Hydrogen Bromine Redox Flow Batteries, Yujia Bai

Doctoral Dissertations

This dissertation represents the consideration of the problems of polymer electrolyte membrane fuel cells (PEMFC) and hydrogen-bromine redox flow batteries (RFB). Due to the importance of water management in PEMFCs, all the experiments were strictly controlled at different water hydration conditions. Water uptake and densities were measured for Nafion^® and a series of 3M ionomer membranes. The thermodynamics of water and polymer was analyzed based on water uptake experiment and calorimetry. Furthermore, partial molar volumes (PMV) of water/membrane system was defined for the first time and used to analyze the interaction between water and polymers. Three states of water …

A Study About Aqueous Reversible Air Electrode- Catalyst, Electrolyte And Structure, Ming Qi

Doctoral Dissertations

Developing a better high energy density rechargeable battery has becoming critically important for several industries. For building such kind of battery, reversible air electrode has been widely accepted as one of the key components. One of the major challenges for reversible air electrode is finding a good bifunctional catalyst to greatly reduce the recharge overpotential and increase the system efficiency. To achieve this goal, a new air battery chemistry based on cobalt salen modified Au catalyst is proposed in this dissertation as a very promising solution. The unique catalytic activity of this catalyst is found to be a two electron …

Development Of A Monitoring Framework For The Detection Of Diversion Of Intermediate Products In A Generic Natural Uranium Conversion Plant, Jennifer L. Ladd-Lively

Doctoral Dissertations

The objective of this work is the development of an on-line monitoring and data analysis framework that could detect the diversion of intermediate products such as uranium dioxide, uranium tetrafluoride, and uranium hexafluoride in a natural uranium conversion plant (NUCP) using a multivariate statistical approach. This was an initial effort to determine the feasibility of this approach for safeguards applications. This study was limited to a 100 metric ton of uranium (MTU) per year NUCP using the wet solvent extraction method for the purification of uranium ore concentrate. A key component in the multivariate statistical methodology was the Principal Component …

Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He

Doctoral Dissertations

Improving the durability and utilization efficiency of the platinum-on-carbon (Pt/C) catalyst is of vital importance to the commercialization of the polymer electrolyte membrane fuel cell (PEMFC). This body of work provides molecular level insights to aid the fulfillment of this goal. Chapter 1 describes the use of molecular dynamics (MD) simulation in an effort to understand the Pt/C degradation issue from the nano-adhesion point of view. The roles of catalyst nanoparticle size, shape, Pt/C surface oxidation and the extent of ionomer film hydration are investigated to study their effects on nano-particle adhesion. It is found that the adhesion force strengthens …

A Tale Of Two Protein Switches: Engineering, Characterizing, And Understanding A Novel And A Natural Switch, James Vincent Price

Doctoral Dissertations

Throughout nature, many proteins provide a specific function in response to some input signal (e.g., phosyphorylation, pH, etc.), a process that is oftentimes described as switching a protein “on” or “off.” The advent of protein engineering has allowed for the creation and understanding of chimeric proteins for uses in a number of applications such as therapeutics, biosensors and energy production. Two proteins, hemagglutinin (HA) of fowl plague influenza virus and a chimeric protein comprising a fusion between the LFA-1 I domain and the EF3 and EF4 hands of calmodulin, have been investigated in this dissertation. Both of these proteins undergo …

Characterization Techniques And Electrolyte Separator Performance Investigation For All Vanadium Redox Flow Battery, Zhijiang Tang

Doctoral Dissertations

The all-vanadium redox flow battery (VRFB) is an excellent prospect for large scale energy storage in an electricity grid level application. High battery performance has lately been achieved by using a novel cell configuration with advanced materials. However, more work is still required to better understand the reaction kinetics and transport behaviors in the battery to guide battery system optimization and new battery material development. The first part of my work is the characterization of the battery systems with flow-through or flow-by cell configurations. The configuration difference between two cell structures exhibit significantly different polarization behavior. The battery output can …

Structure And Morphology Of Sulfonated Polysulfone And Perfluorosulfonic Acid Ionomers, Chen Wang

Doctoral Dissertations

The limitations of conventional perfluorosulfonic acid (PFSA) based membrane materials have provoked the search for alternative materials which can function as the electrolyte in PEM fuel cells operated at higher temperatures (> 100 °C) and without humidification. A novel class of sulfonated poly(phenylene) sulfone (sPSO2) ionomers have shown much higher proton conductivity than typical PFSA membranes at elevated temperatures. In this dissertation, both computational and experimental methods were used to investigate proton transfer, morphological and structural properties of sPSO2 and PFSA ionomers. We have undertaken ab initio electronic structure calculations to understand the primary hydration and the transfer of protons …

Studies Of Reaction Processes For Voloxidation Methods, Jared Allen Johnson

Doctoral Dissertations

Various facets of the voloxidation process and processes that have been derived from the voloxidation process have been investigated since its development over four decades ago. Despite the numerous studies performed, gaps remain in understanding of particular fundamental aspects of the reaction processes. In this work, several of these specific aspects of the oxidation processes for standard voloxidation and NO₂ [nitrogen dioxide] voloxidation are studied experimentally and modeled.

In the case of standard voloxidation, the oxidation rates of simulant UO_­2 [uranium dioxide] pressurized water reactor pellets in oxygen-rich environments were studied with an emphasis on the controlling phenomena …

The Impact Of Biodiesel-Based Na On The Durability Of Cu-Zeolite Scr Catalysts And Other Diesel Aftertreatment Devices, Daniel William Brookshear

Doctoral Dissertations

Biodiesel fuel has increased in popularity in recent years as an alternative fuel choice, but there are concerns related to the impact it will have on diesel engines and aftertreatment systems relative to conventional diesel fuel. One major concern is the presence of sodium (Na) in finished biodiesel fuel due to the use of Na-hydroxyl as a liquid-phase catalyst during biodiesel synthesis. The current study focuses on determining the impact of biodiesel-based Na on the performance and materials characterization of diesel aftertreatment devices including lean NOx traps (LNT), diesel oxidation catalysts (DOC), diesel particulate filters (DPF), and Cu-zeolite selective catalytic …

Industrial Robustness: Understanding The Mechanism Of Tolerance For The Populus Hydrolysate Tolerant Strain Of Clostridium Thermocellum, Jessica Leigh Linville

Doctoral Dissertations

An industrially robust microorganism that can efficiently degrade and convert lignocellulosic biomass into ethanol and next-generation fuels is required to economically produce future sustainable liquid transportation fuels. The anaerobic, thermophilic, cellulolytic bacterium Clostridium thermocellum is a candidate microorganism for such conversions but it, like many bacteria, is sensitive to potential toxic inhibitors developed in the hydrolysate produced during biomass processing. Microbial processes leading to tolerance of the inhibitory compounds found in the pretreated biomass hydrolysate are likely complex and involve multiple genes. In this study, a 17.5% v/v Populus hydrolysate tolerant mutant strain of C. thermocellum was developed by directed …

Multiscale Modeling Of Enzyme-Catalyzed Methanol Production By Particulate Methane Monooxygenase, Katherine K. Bearden

Doctoral Dissertations

In this work, the conversion of methane to methanol by the particulate Methane Monooxygenase (pMMO) enzyme is investigated using a multi-scale modeling approach. This enzyme participates in carbon cycling and aids in the removal of harmful atmospheric methane, converting it to methanol. The interaction between pMMO and a neighboring enzyme that is present in the same organism is studied, and the unknown pMMO active site is elucidated and tested for methane oxidation towards the production of methanol.

Fundamental knowledge of pMMO's mechanism is not fully understood. Understanding how this enzyme works in nature will provide information towards designing efficient synthetic …

Multi-Scale Characterization Of Nanostructured Sodium Aluminum Hydride, Shathabish Narasegowda

Doctoral Dissertations

Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to …

Microfluidic Devices Applied On Enriching Post –Translational Modified Proteins For Proteomics, Hui Xia

Doctoral Dissertations

In this work, microfluidic devices were developed for enriching post-translational modified proteins. Post-translational modifications (PTM) of proteins play essential roles in cellular physiology and disease. The identification of protein substrates and detection of modification site helps understand PTM-mediated regulation in essential biological pathways and functions in various diseases. However, PTM proteins are typically present only at trace levels, making them difficult to identify in mass spectrometry based proteomics. This work study is about the design, fabrication and testing of the microfluidic device for the enrichment of abundant amount of PTMs. Carbonylated protein is used as a representative PTM to illustrate …

Behavior And Effects Of Nanoparticles In Complex Fluid Systems, Chen Wang

Doctoral Dissertations

"The development of nanoscale technologies has greatly expanded the scientific and engineering horizons and also has the potential to turn molecular discoveries into worldwide benefits on multiple fronts. Despite recent extensive efforts, the focus of nanoparticle studies has been on their synthesis and various possible derivatives. In this dissertation, molecular based modeling and simulation studies have been performed to characterize and understand the behavior, properties, and effects of nanoparticles in some important material systems. The results show that small nanoparticles that are highly faceted have significant shape effects, which are not captured by classical continuum-based approaches. When dissolved in confined …

Effect Of Dense Heat Exchanging Internals On The Hydrodynamics Of Bubble Column Reactors Using Non-Invasive Measurement Techniques, Mohammed Khloofh Al Mesfer

Doctoral Dissertations

"Given their efficiency and capital cost reduction, bubble/slurry bubble column reactors are the reactors of choice for Fischer-Tropsch (FT) synthesis, offering clean alternative fuels and chemicals. FT synthesis is an exothermic process that requires many heat exchanging tubes in order to remove heat efficiently and maintain the desired temperature and isothermal operating condition. The impact of the heat exchanging tubes (internals) on the hydrodynamics is not fully understood. Reliably designing and scaling up bubble column reactors requires proper understanding of hydrodynamics, as well as heat and mass transfer parameters.

The main objective of this work is to advance the understanding …

Coupled Geomechanical Reservoir Simulation, Amin Amirlatifi

Doctoral Dissertations

"Founded by Department Of Energy, the Plains CO₂ Reduction (PCOR) Partnership is investigating the Williston Basin as a candidate for sequestering CO₂ emissions from power plants. The State of Missouri, a member of PCOR, lies at the outermost point on the proposed transportation route and consequently faces the highest CO₂ compression and transportation costs. In order to minimize the cost of CO₂ sequestration, it is desirable to find a storage site within the state. The Lamotte sandstone is identified as a suitable sequestration aquifer formation in Missouri with acceptable permeability, porosity, extension, rock strength and water salinity. Using the finite …

Gas Dynamics And Heat Transfer In A Packed Pebble-Bed Reactor For The 4th Generation Nuclear Energy, Rahman Abdulmohsin

Doctoral Dissertations

"Proper analyses of axial dispersion and mixing of the coolant gas flow and heat transport phenomena in the dynamic core of nuclear pebble-bed reactors pose extreme challenges to the safe design and efficient operation of these packed pebble-bed reactors.

The main objectives of the present work are advancing the knowledge of the coolant gas dispersion and extent of mixing and the convective heat transfer coefficients in the studied packed pebble-beds. The study also provides the needed benchmark data for modeling and simulation validation. Hence, a separate effect pilot-plant scale and cold-flow experimental setup was designed, developed and used to carry …

Establishing Well Operability Limits For Frac Pack Sandface Well Completions Using A Screen Erosion Model And Well Completion Score Card, Rickey Hendrix

Doctoral Dissertations

"Completion quality has a direct impact upon the maximum production rate at which a frac pack well should be operated. Best practices for frac pack well completions ensure the highest possible quality for the well completion. A novel frac pack well completion score card was developed based on best practices for frac pack well completions identified through consultation with industry experts. The score card systematically combines and assesses completions data readily available standard completion reports. The outcome of the score card process is a numerical completion quality rating, which combines all well design and frac pack operations information.

The completion …

Heat Transfer And Bubble Dynamics In Bubble And Slurry Bubble Columns With Internals For Fischer-Tropsch Synthesis Of Clean Alternative Fuels And Chemicals, Moses Odongo O. Kagumba

Doctoral Dissertations

"Synthesis gas, a mixture of CO and H₂ obtained from coal, natural gas and biomass are increasingly becoming reliable sources of clean synthetic fuels and chemicals and via Fischer-Tropsch (F-T) synthesis process. Slurry bubble column reactor is the reactor of choice for the commercialization of the F-T synthesis. Even though the slurry bubble column reactors and contactors are simple in structures, their design, scale-up, operation, and performance prediction are still challenging and not well understood due to complex interaction of phases. All the studies of heat transfer have been performed without simultaneously investigating the bubble dynamics adjacent to the heat …

Nanoscale Metal Oxide And Supported Metal Catalysts For Li-Air Battery, Kan Huang

Doctoral Dissertations

"The dissertation work focuses on research and development of durable nanoscale catalysts and supports for rechargeable Li-air batteries that use aqueous catholytes. Transition metal oxides, TiO₂ and Nb₂O₅ in particular, were prepared from a sol-gel process in the form of nanocoatings (5~50 nm) on carbon nanotubes (CNTs) and studied as catalyst supports. Carbon doping in the oxides and post annealing significantly increased their electronic conductivity. Pt catalyst on the support with TiO₂ (Pt/c-TiO₂/CNTs) showed a much better oxygen reduction reaction (ORR) activity than a commercial Pt on carbon black (Pt/C). Negligible loss ( …

Minimizing Formation Damage For Preformed Particle Gels Treatment In Mature Reservoirs, Mahmoud Omran Elsharafi

Doctoral Dissertations

"This research studied the effect of preformed particle gels (PPGs) on unswept, low-permeable zones/areas. The objective was to find methods that minimized the damage caused by PPGs on unswept, low-permeable zones/areas, thus improving PPG treatment efficiency. These results can help to identify of the best PPG types, particle sizes, and brine concentrations for specific reservoirs and treatments. This study used sandstone core samples with various degrees of permeability. Two types of particle gels, a strong Daqing gel (DQ) and a weak Liquiblock™ 40k gel (40K), were used, each with a different strength.

This research included two stages. Firstly, both a …

Modeling And Analysis Of Dynamic Behavior Of Adsorption Stratified Column Beds Packed With Partially Fractal Porous Adsorbent Particles, Min Li

Doctoral Dissertations

"In this work novel porous adsorbent media having partially fractal structures and stratified packed-beds are constructed and their dynamic performance with respect to their adsorptive capacity through the construction and solution of rigorous models is studied. The results show that conventional columns packed with partially fractal porous adsorbent particles provide larger breakthrough times and dynamic utilization of the adsorptive capacity of the column when compared with those of conventional columns employing conventional adsorbent particles which do not possess a partially fractal structure. Furthermore, stratified column beds exhibit superior species separation performance than conventional columns when they are packed with either …

Scaleup And Hydrodynamics Study Of Gas-Solid Spouted Beds, Shreekanta Basavaraj Aradhya

Doctoral Dissertations

"A thorough understanding of the complex flow structure of gas-solid spouted bed is crucial for design, scale-up and performance. Advanced gas-solid optical probes were developed and used to evaluate different hydrodynamic parameters of spouted beds. These optical probes measure solids concentration, velocity and their time series fluctuations. Since solids concentration needs to be converted to solids holdup through calibration, for meaningful interpretation of results, a novel calibration method was proposed (which is inexpensive and reliable compared to the current reported methods) and validated in the present study. The reported dimensionless groups approach of spouted bed scale-up was assessed and was …