Chemical Engineering Commons^™

Extracellular Matrix From Whole Porcine Heart Decellularization For Cardiac Tissue Engineering, Nima Momtahan

Theses and Dissertations

Heart failure is one of the leading causes of death in the United States. Every year in the United States, more than 800,000 people are diagnosed with heart failure and more than 375,000 people die from heart disease. Current therapies such as heart transplants and bioartificial hearts are helpful, but not optimal. Decellularization of porcine whole hearts followed by recellularization with patient-specific human cells may provide the ultimate solution for patients with heart failure. Great progress has been made in the development of efficient processes for decellularization, and the design of automated bioreactors. In this study, the decellularization of porcine …

Aminoacyl-Trna Synthetase Production For Unnatural Amino Acid Incorporation And Preservation Of Linear Expression Templates In Cell-Free Protein Synthesis Reactions, Andrew Broadbent

Theses and Dissertations

Proteins—polymers of amino acids—are a major class of biomolecules whose myriad functions facilitate many crucial biological processes. Accordingly, human control over these biological processes depends upon the ability to study, produce, and modify proteins. One innovative tool for accomplishing these aims is cell-free protein synthesis (CFPS). This technique, rather than using living cells to make protein, simply extracts the cells' natural protein-making machinery and then uses it to produce protein in vitro. Because living cells are no longer involved, scientists can freely adapt the protein production environment in ways not otherwise possible. However, improved versatility and yield of CFPS protein …

The Influence Of Season, Heating Mode And Slope Angle On Wildland Fire Behavior, Jonathan R. Gallacher

Theses and Dissertations

Wildland fire behavior research in the last 100 years has largely focused on understanding the physical phenomena behind fire spread and on developing models that can predict fire behavior. Research advances in the areas of live-fuel combustion and combustion modeling have highlighted several weaknesses in the current approach to fire research. Some of those areas include poor characterization of solid fuels in combustion modeling, a lack of understanding of the dominant heat transfer mechanisms in fire spread, a lack of understanding regarding the theory of live-fuel combustion, and a lack of understanding regarding the behavior of flames near slopes. In …

Sustainable P2 Design For Batch-Based Specialty Chemical Manufacture, Brigitte Pastore

Theses and Dissertations

A case study has been conducted on the reduction of n-methyl-2-pyrrilodone (NMP) solvent waste in the manufacture of polyimide and polybenzoxazole precursors. The evaluation includes the environmental and economic assessment of solvent recovery and substitution strategies. A two-step distillation process proved effective in recovering 95% of the NMP at a purity of 99.97% from the aqueous solvent waste stream. Yearly operating costs were reduced by 83% and total life cycle emissions were reduced by 44%, due to reduction in virgin NMP use and hazardous waste disposal. With capital acquisition, the recovery option would still result in a net present value …

High-Temperature, High-Pressure Viscosities And Densities Of Toluene, Aaron J. Rowane

Theses and Dissertations

High-temperature, high-pressure (HTHP) conditions are exemplified in ultra-deep petroleum reservoirs and can be exhibited within diesel engines. Accurate pure component hydrocarbon data is essential in understanding the overall behavior of petroleum and diesel fuel at these conditions. The present study focuses on the HTHP properties of toluene since this hydrocarbon is frequently used to increase the octane rating of gasoline and toluene occurs naturally in crude oil. In this thesis experimental densities and viscosity are presented to 535 K and 300 MPa extending the database of toluene viscosity data to higher temperature than previous studies. The data is correlated to …

Development Of A Pressure Swing Adsorption (Psa) Cycle For Co2 Capture From Flue Gas Using A 4-Bed Psa Apparatus, Joshua White

Theses and Dissertations

Pressure swing adsorption is an effective way to capture CO2 from flue gases in energy plants. Pressure swing adsorption utilizes an adsorbent’s selectivity to a specific compound to remove it from a feed stream. Zeolite 13X was used for this research to obtain a high purity and recovery of CO2 at a higher feed flow than previous research. The first part of the work was to use in house FORTRAN based Dynamic Adsorption Process Simulator (DAPS) that uses the finite difference method and the time adaptive Differential- Algebraic Equation (DAE) solver called DASPK to narrow down appropriate experiment criteria for …

Biodegradable Hybrid Tissue Engineering Scaffolds For Reconstruction Of Large Bone Defects, Danial Barati

Theses and Dissertations

Complex skeletal injuries and large bone fractures are still a significant clinical problem in US. Approximately 1.5 million Americans (veterans, their families, and civilians) every year suffer from bone loss due to traumatic skeletal injuries, infection, and resection of primary tumors that require extensive grafting to bridge the gap. The US bone graft market is over $2.2 billion a year. Due to insufficient mechanical stability, lack of vascularity, and inadequate resorption of the graft, patients with traumatic large skeletal injuries undergo multiple costly operations followed by extensive recovery steps to maintain proper bone alignment and length. Current strategies for repairing …

Synthesis Of Well Dispersed Supported Metal Catalysts By Strong Electrostatic Adsorption And Electroless Deposition, John Meynard Macasero Tengco

Theses and Dissertations

Enhancing the catalytic performance of heterogeneous catalysts can be done by increasing active site count as well as modification of the physico-chemical characteristics of the catalyst material. For supported metal nanoparticles this can be achieved by decreasing particle size, thus increasing dispersion or metal utilization on the surface of the particles, while modification of metal properties can be attained by addition of a secondary metal that has a strong interaction to the primary metal, beneficial for a given reaction. In addition, the accessibility of the metal surface is necessary for reliable performance of catalysts. For carbon supported catalysts, Temperature Programmed …

Rational Design And Synthesis Of Pt/Silica-Alumina Metal-Acid Bifunctional Catalysts, Jadid Ettaz Samad

Theses and Dissertations

In the domain of rational catalyst design and synthesis, Strong Electrostatic Adsorption (SEA) has been applied with tremendous potential and use. In this study, SEA method has been advanced to thick slurries as well as to mixed oxide systems with a view to synthesizing stable, active and selective catalysts fine-tuned for specific applications.

The main objective was to synthesize metal-acid bifunctional catalysts with controlled ratio and proximity between metal and acid sites in order to analyze their effects on a bifunctional reaction. At first, the difference in charging behavior of silica and alumina in solution was used to selectively deposit …

Rational Synthesis To Optimize Ruthenium-Based Biomass Conversion Catalysts, Shuo Cao

Theses and Dissertations

With worldwide petroleum resources dwindling and greenhouse gas emissions rising, it is urgent to find renewable replacements for petroleum-derived products. A biomass-derived chemical with high potential as a platform intermediate, γ-valerolactone (GVL) can be readily synthesized by hydrogenation of levulinic acid (LA), itself a common biomass intermediate, using supported Ru catalysts. Overall, vapor phase hydrogenation is more energy sensitive as the higher boiling point of LA (~245°C) and requires a high energy input, comparable to liquid phase hydrogenation, which is more economical. To date the literature on many novel biomass conversion processes such as the hydrogenation of LA to GVL …

Design And Development Of A High-Temperature High-Pressure Rolling Ball Viscometer/Densimeter And Evaluation Of Star Polymer-Solvent Mixtures, Matthew Stanton Newkirk

Theses and Dissertations

Modern automotive applications such as transmission clutch plates, combustion chambers, diesel fuel injector tips, and axle gears and friction plates operate at temperatures that can exceed 250°C and pressures of 40,000 psia. Industrial practice is to add homopolymers and copolymers to base oils to modify bulk fluid viscosity and frictional properties for these demanding applications. However, designing polymeric additives for lubricants and predicting their performance is limited by the lack of available high-temperature high-pressure (HTHP) viscosity and density data needed to test contemporary lubricity models. Thus, a major objective of this thesis is the design, development, and commissioning of a …

A Theoretical Simulation Of The Settling Of Proppants In A Hydraulic Fracturing Process, Nisreen Alseamr

Theses and Dissertations

Hydraulic fracturing is a process for the extraction of hydrocarbons from underground formations. It involves pumping a specialized fluid into the wellbore under high pressures to form and support fractures in the rock. Fracturing stimulates the well to increase the production of oil and the natural gas which are the pillars of the energy economy. Key to this process is the use of proppants, which are solid materials used to keep the fractures open. Understanding the transport of proppant particles through a fluid is important to improve the efficiency and reduce environmental impact of fracturing. An increase of the settling …

Uncertainty Quantification In Computational Catalysis, Eric Alan Walker

Theses and Dissertations

This dissertation augments the field of computational catalysis with uncertainty quantification. An efficient tool to describe the energetics and structure of atomistic systems is density functional theory (DFT). DFT may be used to understand how catalysts work although DFT is inexact in nature due to approximations necessary for computational tractability. These approximations in DFT cause uncertainty in microkinetic model results for catalytic systems. Therefore, reliable model results gained from DFT include a quantification of uncertainty. The case study to examine a systematic framework for uncertainty quantification is water-gas shift (WGS CO+H2O⇌CO2+H2) reaction by Pt/TiO2 catalyst.

Uncertainties are represented with probabilities …

Mathematical Modeling Of Transport And Corrosion Phenomenon Inside High Temperature Molten Salt Systems, Bahareh Alsadat Tavakoli Mehrabadi

Theses and Dissertations

In today's world, alternative clean methods of energy are needed to meet growing energy demands. Concentrating solar thermal power, more commonly referred to as CSP, is unique among renewable energy generators because even though it is variable, like solar photovoltaic and wind, it can easily be coupled with thermal energy storage as well as conventional fuels, making it highly dispatchable. One challenge with concentrated solar power (CSP) systems is the potential corrosion of the alloys in the receivers and heat exchangers at high-temperature (700-1000 °C), which leads to a reduction of heat transfer efficiency and influences the systems durability. The …

Development Of Novel High-Throughput Methodologies To Evaluate The Thermal Stability Of High-Temperature Thin-Film Crystals For Energy Applications, Jonathan Kenneth Bunn

Theses and Dissertations

High temperature materials are used in a variety of energy applications such as jet turbines, high temperature sensors, and solid oxide fuel cells (SOFCs). Discovery of new materials and their optimization represents a difficult engineering challenge, as the materials have to be designed to have a high figure of merit during intense high temperature operations.

The large number of engineering considerations involved in the identification and optimization of such materials makes traditional one-by-one material investigations prohibitively time consuming. The time needed to explore large parameter domains can be significantly decreased through the use of high-throughput experimentation (HTE). HTE is an …

The Oxidation And Decoration Chemistry Of Platinum And Palladium Nanoparticles On Carbon Supports, Ritubarna Banerjee

Theses and Dissertations

Ultrasmall platinum and palladium nanoparticles supported on carbon are used in a wide variety of industrial catalytic processes including hydrogenation-dehydrogenation reactions, isomerization of hydrocarbons, ammonia and formic acid decomposition, the oxidation of carbon monoxide, alcohols and ammonia, and fuel cells. This dissertation covers three aspects of the chemistry of these ultrasmall, carbon supported nanoparticles.

In the first vein of work, the oft-observed discrepancy in Pd nanoparticle size estimation between chemisorption and other methods such as STEM and XRD is explored. It is demonstrated that lower-than-expected chemisorption uptake can stem from not only residual chloride, but also from the decoration of …

Two-Stage Psa System For Co2 Removal And Concentration During Closed-Loop Human Space Exploration Missions, Hanife Erden

Theses and Dissertations

A novel two-stage pressure swing adsorption (PSA) system has been developed to remove metabolic CO2 removal from the spacecraft cabin air of the International Space Station (ISS). This PSA system enriches and recovers the CO2 to make it suitable for use in a Sabatier reactor (CO2 reduction). This two-stage PSA process utilizes Stage 1 to concentrate metabolic CO2 from about 0.2667 vol% to about 40 to 60 vol% and Stage 2 to further enrich the CO2 product from Stage 1 up to > 97 vol% CO2, while recovering at least 95% of it, which corresponds to removing 4.0 kg/day of CO2. …

Investigation Of Heterogeneous Chemistry Of Pollutants In Flue Gas For Air And Oxy-Combustion, Benjamin D. Galloway

Theses and Dissertations

Due to increasing concerns associated with the emissions created from the combustion of coal, technologies are being modified or developed to limit many of these harmful emissions. The content of this thesis will focus on two technologies and the specific pollutants they seek to limit. The first investigated is selective catalytic reduction, which is utilized to decrease NO emissions. Due to the recent promulgation of the MATS regulations, focus has been on reducing the Hg emissions through the optimization of the SCR catalysts, making them bi-functional for NO reduction and Hg oxidation. The work presented here focuses on a novel …

Electrochemical Reduction Of Carbon Dioxide On Carbon Nanostructures: Defect Structures & Electrocatalytic Activity, Pranav Parag Sharma

Theses and Dissertations

The advantages of the electrochemical conversion of carbon dioxide to fuels using renewable energy sources are two-fold: (1) it has the potential to accomplish a carbon-neutral energy cycle and (2) it can provide an approach to tackle the environmental challenges caused by anthropogenic carbon dioxide emissions. Although thermodynamically possible, the kinetics of carbon dioxide reduction to fuels remains challenging and therefore, an efficient and robust electrocatalyst is needed to promote the reaction. The ideal catalyst for the electrochemical CO2 reduction must be capable of mediating multiple proton-coupled electron transfer reactions at low overpotentials, suppressing the concurrent hydrogen evolution reaction, converting …

Solving Atomic Structures Using Statistical Mechanical Searches On X-Ray Scattering Derived Potential Energy Surfaces, Christopher James Wright

Theses and Dissertations

Engineering the next generation of materials, especially nanomaterials, requires a detailed understanding of the material’s underlying atomic structure. These structures give us better insight into structure-property relationships, allowing for property driven material design on the atomic level. Even more importantly, understanding structures in-situ will translate stimuli and responses on the macroscopic scale to changes on the nanoscale. Despite the importance of precise atomic structures for materials design, solving atomic structures is difficult both experimentally and computationally. Atomic pair distribution functions (PDFs) provide information on atomic structure, but the difficulty of extracting the PDF from x-ray total scattering measurements limits their …

An Injectable Stem Cell Delivery System For Treatment Of Musculoskeletal Defects, Shirae Leslie

Theses and Dissertations

The goal of this research was to develop a system of injectable hydrogels to deliver stem cells to musculoskeletal defects, thereby allowing cells to remain at the treatment site and secrete soluble factors that will facilitate tissue regeneration. First, production parameters for encapsulating cells in microbeads were determined. This involved investigating the effects of osmolytes on alginate microbead properties, and the effects of alginate microbead cell density, alginate microbead density, and effects of osteogenic media on microencapsulated cells. Although cells remained viable in the microbeads, alginate does not readily degrade in vivo for six months. Therefore, a method to incorporate …

Methane Separation And Purification Via Pressure Swing Adsorption, Lutfi Erden

Theses and Dissertations

Investigations on alternative energy sources have gained increasing attention due to significant shortage in the fossil fuel reserves and increase on the usage of internal combustion engines. Natural gas which mainly consists of Methane has a significant role in short term solution of this issue. Although methane as a greenhouse gas is over 20 times more potent by weight than carbon dioxide, if released directly into the atmosphere, it is a valuable energy source. However, methane is not extracted % 100 pure from the source. Natural gas generally contains many other contaminants such as water, other hydrocarbons, Carbon dioxide, Nitrogen, …

Development Of Highly Active And Stable Hybrid Cathode Catalyst For Pemfcs, Won Suk Jung

Theses and Dissertations

Polymer electrolyte membrane fuel cells (PEMFCs) are attractive power sources of the future for a variety of applications including portable electronics, stationary power, and automobile application. However, sluggish cathode kinetics, high Pt cost, and durability issues inhibit the commercialization of PEMFCs. To overcome these drawbacks, research has been focused on alloying Pt with transition metals since alloy catalysts show significantly improved catalytic properties like high activity, selectivity, and durability. However, Pt-alloy catalysts synthesized using the conventional impregnation method exhibit uneven particle size and poor particle distribution resulting in poor performance and/or durability in PEMFCs. In this dissertation, a novel catalyst …

In Situ Ir Spectroscopic Investigation Of Noble Metal Catalysts Related To The Reduction Of Automotive Exhaust Emissions, Zhiyong Wang

Theses and Dissertations

The reduction of automotive exhaust emissions has been one of the hottest topics in catalysis community since 1970s. Thanks to the development of three-way catalysts, main auto-exhaust pollutants, such as carbon monoxide, nitrogen oxides and unburned hydrocarbons, can be removed simultaneously. Nowadays, diesel engines and lean-engines become more and more popular due to their high fuel-efficiency and low CO2 emissions. Unfortunately, conventional three-way catalysts are not effective at reducing the NOx emissions from these engines due to the excess oxygen in the exhaust stream. Platinum catalysts were found to be highly active for selective NO reduction with hydrocarbons in excess …

Preparation And Characterization Of Pt-Ru Bimetallic Catalysts Using Electroless Deposition Methods And Mechanistic Study Of Re And Cs Promoters For Ag-Based, High Selectivity Ethylene Oxide Catalysts, Weijian Diao

Theses and Dissertations

Pt-Ru bimetallic catalysts are widely used for direct methanol fuel cells, biomass upgrading and hydrocarbon refining and offer unique properties compared to Pt or Ru monometallic catalysts due to ensemble effects, electronic effects, and/or bifunctional effects. To achieve better performance, strong metal-metal interactions and true bimetallic surface are needed. Electroless deposition (ED) methods are used in our laboratory to synthesize such bimetallic catalysts. In this study, two series of Ru@Pt/C (Pt deposited on Ru surfaces) and Pt@Ru/C (Ru deposited on Pt surfaces) catalysts have been synthesized. Characterization data from temperature programmed reduction (TPR), selective chemisorption, X-ray photoelectron spectroscopy (XPS), and …

Supported Group Ib-Pd Bimetallic Catalysts Prepared By Electroless Deposition And Galvanic Displacement For Selective Hydrogenation Of Acetylene, Yunya Zhang

Theses and Dissertations

Ethylene is the building block for many chemical intermediates in the petrochemical industry. The current worldwide ethylene production is over 150 million tons per year and demand increases by 3-5% annually. However, ethylene produced from steam cracking of light naptha contains up to 2% acetylene which acts as a poison for the downstream ethylene polymerization catalysts. Selective hydrogenation of acetylene in the ethylene stream using supported Pd catalysts is the industrially preferred method of lowering acetylene to acceptable ppm levels (< 5 ppm). Due to inferior selectivity at high acetylene conversion and the formation of “green oil”, or ethylene/acetylene oligomers, during reaction, small amounts of Group IB metals have been added to improve the performance of current generation catalysts. However, the bimetallic effects of the above additives have not been experimentally confirmed, possibly because the conventional methods of catalyst preparation result in both monometallic and bimetallic particles with varying compositions. This in turn makes it difficult to determine the position of the two metallic components, and bimetallic interactions typically occur only when the two metals form proximal contact instead of separate particles. In this study, a series of Ag- and Au-Pd/SiO2 bimetallic catalysts were prepared by electroless deposition (ED) with incremental and controlled coverages of Ag and Au on Pd. The selectivity of acetylene to ethylene and turnover frequencies of acetylene conversion were enhanced at high coverages of Ag and Au on Pd surfaces due to the transition of acetylene adsorption modes, which was further confirmed by the kinetics of acetylene hydrogenation. The similar performance trends for Ag- and Au-Pd/SiO2 suggest that the bimetallic effect for these catalysts was likely geometric and not electronic in nature. For comparison, a series of reverse Pd-Ag/SiO2 bimetallic catalysts where variable coverages of Pd were deposited onto Ag surfaces was prepared using galvanic displacement (GD) of Ago by Pd2+ to further explore the nature of bimetallic effects for selective acetylene hydrogenation. Unlike for the earlier case for Ag on Pd surfaces using ED, for samples prepared by GD there was considerably diffusion of Pd into the Ag lattice to give greater electronic interactions between these two metals, which limited selectivity of acetylene hydrogenation to form ethylene.

Surface Modification Of Nanodiamond And Its Incorporation In Nanodiamond/Peek Nanocomposites, Zahidul Wahab

Theses and Dissertations

The continued miniaturization of electronic device components requires new lightweight polymers with high thermal stability, high thermal conductivity, low electrical conductivity, and low dielectric constant. Composites of nanodiamond (ND) and poly(ether ether ketone) (PEEK) are candidates for these applications due their unique combination of properties. The objectives of this research are to explore new routes for surface functionalization of nanodiamond (ND), develop methods for maximizing dispersion of ND as a nano-scale filler in PEEK, and characterize the effect of dispersed ND on the mechanical, thermal and dielectric properties of ND/PEEK composites. Initial attempts to disperse different kinds of commercially available, …

Impact Of Formulation And Processing Parameters On Mechanical Properties Of Magadiite/Elastomer Composites, Yating Mao

Theses and Dissertations

This work seeks a better understanding of mechanical reinforcement and energy dissipation in elastomer composites containing the layered silicate magadiite (MGD, Na2Si14O29·nH2O). We characterized the elastomer’s accessibility into MGD interlayer spaces and studied the factors that influence the composite mechanical properties. We also compare the mechanical reinforcement of MGD with montmorillonite (MMT, a layered aluminosilicate clay mineral), which is widely used as filler in other kinds of nanocomposites. The study explores the grafting chemistry, vulcanization, and reinforcement mechanism in MGD/elastomer composites, which may help us to formulate the platelet/elastomer composites with superior mechanical properties and performance in the future. We …

Development Of Ultra-Low Loading Of Compressive Pt Lattice Cathode Catalyst On Highly Stable Support For Pemfc Automotive Applications, Tianyuan Xie

Theses and Dissertations

The major barriers in the commercialization of the fuel cell technology for automotive applications are the cost and durability of the Pt catalyst and the support stability at high potentials. The U.S. Department of Energy (DOE) targets direct hydrogen fuel cell systems for transportation to meet 65% peak-efficiency, 5,000 hour durability with a mass production cost of $40/kW by 2020. Currently in 2015, the system can be operated at peak energy efficiency of 60% for 3,900 hours with cost of $55/kW. To meet these targets, precious metal loadings must be greatly reduced without altering the catalyst stability. The primary objective …

Stochastic Simulation Of Lagrangian Particle Transport In Turbulent Flows, Guangyuan Sun

Theses and Dissertations

This dissertation presents the development and validation of the One Dimensional Turbulence (ODT) multiphase model in the Lagrangian reference frame. ODT is a stochastic model that captures the full range of length and time scales and provides statistical information on fine-scale turbulent-particle mixing and transport at low computational cost. The flow evolution is governed by a deterministic solution of the viscous processes and a stochastic representation of advection through stochastic domain mapping processes. The three algorithms for Lagrangian particle transport are presented within the context of the ODT approach. The Type-I and -C models consider the particle-eddy interaction as instantaneous …