Chemical Engineering Commons^™

Investigation Of Three-Way (Twc), Lean Nox Trap (Lnt) And Selective Catalytic Reduction (Scr) Catalysts For Control Of Nox Emissions From Lean-Burn Engines, Christopher Dominic Digiulio

Theses and Dissertations

Lean-burn gasoline engines are approximately 10% more fuel efficient than conventional, stoichiometric-burn ones. Although relatively modest, if implemented across the entire U.S. automotive fleet, this improvement in fuel economy could have far-reaching implications on the amount of gasoline imported in the country on an annual basis. However, the development of a cost-effective catalytic converter catalyst capable of meeting emission regulations for lean-burn vehicles still represents a major technical challenge. Currently, lean NOX trap (LNT) and selective catalytic reduction (SCR) catalysts are used for this purpose, but both systems suffer from significant drawbacks. For example, LNT catalysts generally require high platinum …

New Approach For Modeling Hybrid Pressure Swing Adsorption-Distillation Processes, Fan Wu

Theses and Dissertations

A new methodology for modeling hybrid pressure swing adsorption (PSA)-distillation processes has been developed. Two hybrid systems were simulated as examples. One is for ethanol dehydration, and the other is for propane/propylene separation. Firstly, a distillation process simulator such as Chemsep was used to simulate the distillation process of the hybrid system, in which the PSA unit was treated as a "black box" with an assumed process performance. In this way, a hybrid PSA-distillation process can be analyzed simply by performing mass balances around these units and running Chemsep to determine the possibility of energy saving compared to a reference …

Development Of High-Throughput Catalyst Screening For Ammonia Based Selective Catalytic Reduction Of Nitric Oxide With Parallel Analysis Using Fourier Transform Infrared Imaging, Shahriar Salim

Theses and Dissertations

Lean-burn engines, which operate under excess air to fuel ratio offer significant fuel efficiency as well as contribute to the reductions of greenhouse gas emissions. However, lean burn engines produce three main pollutants carbon monoxide (CO), nitrogen oxides (NOx) and unburned or partially burned hydrocarbons (HC), which have detrimental effect on both environment and human life. The conventional three way catalyst (TWC) which was designed to reduce NOx under stoichiometric conditions is not effective under lean-burn engine exhaust condition. Recent studies have shown that copper (Cu) exchanged chabazite (CHA) type zeolites are very promising catalysts for urea or ammonia (NH3) …

Asymmetric Hydrogenation Of Α, Β-Unsaturated Carboxylic Acid Over Chiral-Modified Palladium Catalyst, Shuai Tan

Theses and Dissertations

The production of optically pure chemicals through enantioselective catalytic reaction plays a key role a variety of industrials (e.g., pharmaceutical, agrochemical). Among several established methods, chiral-modified supported transition metal catalyst has been addressed attentions since past decades due to an environmental concern. Asymmetric hydrogenation of α, β-unsaturated carboxylic acid over Pd catalyst is of particular interest in this area. Nevertheless, the spectroscopic aspect, as well as the kinetic mechanism of such reaction system are still not clearly understood and require further study. In this work, a model catalytic reaction has been investigated from both spectroscopic and kinetic view. To be …

Theoretical Investigation Of The Water-Gas Shift Reaction At The Three Phase Boundary Of Ceria Supported Platinum Metal Clusters, Sara Aranifard

Theses and Dissertations

The Water-Gas Shift (WGS: CO+H2O→CO2+H2) reaction is a key step in hydrogen fuel processing for mobile fuel cell applications. Since the reaction is equilibrium-limited and exothermic, high conversions are favored by low temperatures. However, conventional low-temperature shift catalysts are not active enough. Reducible oxide supported small noble metal clusters have shown excellent activity as low temperature WGS catalysts and it is generally believed that these catalysts are bifunctional. In other words, the reaction occurs at the three-phase boundary (TPB) of the noble metal, the reducible oxide, and the gas phase. The small noble metal cluster adsorbs/activates the CO molecules and …

Understanding The Effect Of Balance Of Plant Contaminants On Pemfcs Performance: Models, Mechanisms, Functional Group, Hyun-Seok Cho

Theses and Dissertations

This dissertation considers contamination of a proton exchange membrane fuel cell (PEMC) that may result from chemicals that leach from balance of plant (BOP) materials. Both model predictions and experimental data are presented. The model is used to predict the cathode contamination impact on the Pt/C electrode and the membrane assuming no transport of contaminant from cathode to anode. The model prediction accounts for the contamination mechanisms such as adsorption, ion-exchange, absorption and three sources of voltage (i.e., performance) loss. The simple 2-D time-dependent model is developed by considering well known chemical engineering concepts of Langmuir adsorption, partition coefficients, plug …

Enantioselective Hydrogenation Of Α-Methylcinnamic Acid Over Pd/Al2o3: A Spectroscopic And Kinetic Study, Xiaojing Sun

Theses and Dissertations

Hydrogenation of C=C in α-methylcinnamic acid (MCA) is studied by both kinetic and spectroscopic method. Kinetic study was in a semi-batch reactor. The reaction activity is strongly solvent dependent, while selectivity remains almost unaffected. The reaction is zero order in hydrogen pressure and first order in MCA. The presence of cinchonidine does not affect the reaction order with respect to either acid or H2 pressure, but has a significant inhibiting effect on the reaction rate. The catalyst exhibits stable activity during the reaction with no sign of deactivation. The adsorption and hydrogenation in dichloromethane, isopropanol and 1, 4-Dioxane over the …

Rational Design Of Perovskite Based Anode Materials For Solid Oxide Fuel Cells: A Computational Approach, Suwit Suthirakun

Theses and Dissertations

A key challenge in the development of solid oxide fuel cell (SOFC) technology is related to finding a suitable replacement for Ni-based cermet anodes. Although conventional Ni-based electrodes exhibit excellent catalytic activity and current collection, they suffer from several limitations such as instability upon redox cycling, nickel sintering, and sulfur and carbon poisoning when exposed to practical hydrocarbon fuels. Therefore, alternative anode materials need to be developed for SOFCs. Among the novel anode electrodes, perovskite based materials are of great interest because they have been shown to satisfy most intrinsic SOFC anode requirements such as high thermodynamic stability in anodic …

The Rational Synthesis Of Supported Noble Single Or Bimetallic Catalysts By Electrostatic Adsorption, Hyeran Cho

Theses and Dissertations

Many catalysts are today prepared by impregnation (also called incipient wetness or dry impregnation) in which nominal amounts of metals are placed into the amount of solution just necessary to fill the pore volume of the support material. While dry impregnation (DI) is simple and the amounts of metals easily controlled, no attention is paid to metal-support or metal-metal interaction. When DI-deposited metal precursors are reduced, the particles tend to be large in size and there is often ppor contact between two metals in a bimetallic system. In this work we demonstrate the application of "strong electrostatic adsorption" (SEA) for …

Squeeze Flow Of Highly Concentrated Suspensions, Mohsen Nikkhoo

Theses and Dissertations

In this thesis we investigated through experiment and model, the anomalous normal stress distribution during constant-force squeeze flow of highly concentrated suspensions. Using pressure-sensitive films the normal stress distribution is measured in suspensions of glass spheres in a Newtonian liquid undergoing constant-force squeeze flow. At volume fractions of solids up to 0.55, the normal stress distribution is independent of volume fraction and almost identical to the parabolic pressure distribution expected for Newtonian fluids. However, at higher volume fractions, the normal stresses become an order of magnitude larger near the center and very low beyond that region. At these high volume …

Comparison Of A Particle Filter And Other State Estimation Methods For Prognostics Of Lithium-Ion Batteries, Eric Alan Walker

Theses and Dissertations

A particle filter (PF) is shown to be more accurate than non-linear least squares (NLLS) and an unscented Kalman filter (UKF) for predicting the remaining useful life (RUL) and time until end of discharge voltage (EODV) of a Lithium-ion battery. The three algorithms track four states with correct initial guesses and 5% variation on the initial guesses. The more accurate prediction performance of PF over NLLS and UKF is reported for three Lithium-ion battery models: a data-driven empirical model, an equivalent circuit model, and a physics-based single particle (SP) model.

Gelation Characteristics And Osteogenic Differentiation Of Stromal Cells In Inert Hydrolytically Degradable Micellar Polyethylene Glycol Hydrogels, Danial Barati

Theses and Dissertations

The use of polyethylene glycol (PEG) hydrogels in tissue engineering is limited by their persistence in the site of regeneration. In an attempt to produce degradable PEG-based hydrogels while preserving the unique properties of PEG, linear (LPELA) and star (SPELA) poly(ethylene glycol-co-lactide) acrylate, star (SPEDA) poly(ethylene glycol-co-dioxanone), star (SPEGA) poly(ethylene glycol-co-glycolide) acrylate as the least hydrophobic and (SPECA) poly(ethylene glycol-co-caprolactone) as the most hydrophobic macromonomers with short hydrophobic segments were synthesized. The hydrogels were characterized with respect to gelation time, modulus, water content, sol fraction, degradation, and osteogenic differentiation of encapsulated marrow stromal cells (MSCs). Chain extension of PEG with …

Effect Of Nanoparticle Size, Support, And Potassium Dopant On Ruthenium Activity For Levulinic Acid (La) Hydrogenation To Γ-Valerolactone (Gvl), Shuo Cao

Theses and Dissertations

The purpose of this thesis is to study the effect of nano-particle size, support and potassium dopant on ruthenium activity on the levulinic acid (LA) hydrogenation to ã-valeroactone (GVL).In hydrogenation reaction, H2 as the gas phase reactant reacts with the metal atoms at the surface of particle size, thus a high level of metal dispersion is critical to maximize the amount of atoms on the surface. This reaction has been widely investigated by varied metal supported catalysts and proved that Ru is the most active metal for it. However, most of researchers only focused on the reaction pathway, rather than …

The Effect Of Bi-Polar Plate And Membrane Materials On Water Transport In Pemfcs, Visarn Lilavivat

Theses and Dissertations

An analysis of liquid water transport and removal in Proton Exchange Membrane Fuel Cells (PEMFCs) as affected by different membranes and the geometry and surface roughness of bipolar plates on is presented. Four topics are considered. First, the channel dimension and shape of various flow fields have been shown to affect the cell performance and the uniformity in the distributions of current. Typical variations in the channel width, height, and undercut that may occur with manufactured metal plates are studied. These sample-to-sample variations and distributions are studied and compared with laboratory-scale graphite plates. The goal of the work is to …

Effect Of Matrix Modulus On Cancer Stem Cells And Tumorsphere Formation In Three-Dimensional-Engineered Matrix, Samaneh Kamali Sarvestani

Theses and Dissertations

Maintenance of cancer stem cells (CSCs) is regulated by their microenvironment. As cancer cells are affected by many factors in their microenvironment, a major challenge is to isolate the effect of a specific factor on cancer stem cells (CSCs) while keeping other factors unchanged. We have developed a synthetic inert 3D polyethylene glycol diacrylate (PEGDA) gel culture system as a unique tool to study the effect of microenvironmental factors on CSCs response. Synthetic hydrogels provide the flexibility to design three-dimensional (3D) matrices to isolate and study individual factors in the tumor microenvironment.

The objective of this work was to investigate …

Studying On Capacity Fade Mechanisms Of Li-Ion Batteries Through Modeling, Yiling Dai

Theses and Dissertations

Li-ion batteries are promising candidates as power sources for hybrid electric/electric vehicles, as well as storage devices for renewable energies (wind, solar). Longer life batteries are more desirable for large-scale application, which would help lower the capital cost ($/KW) and improve the system stability. However, the aging problem of Li-ion batteries obstructs their fast penetration into these markets. The cell life can be improved based on an in-depth understanding of the fade mechanisms. The purpose of this dissertation is to explore, through a mathematical modeling approach, failure mechanisms of Li-ion batteries.

To study the capacity fade of a LiMn2O4 (LMO) …

Parsing The Effects Of Physical Microenvironmental Cues On Stem Cell Adhesion And Lineage Specification, Greg M. Harris

Theses and Dissertations

Tissue engineering is a broad field geared toward improving or replacing biological material and comprises an immense collection of biological nuances to consider before strategies for clinical applications can be fully realized. Physical and biochemical signals are responsible for making up a cell's microenvironment to guide morphology and function through cell-extracellular matrix signaling, cell-cell signaling, and soluble signaling. In particular, a deeper understanding of these cell-extra cellular matrix factors guiding stem cell adhesion, spreading, and differentiation is crucial to harnessing the potential to develop tissue for regenerative purposes. Mounting evidence suggests that physical cues are a key to understanding the …

Streamlined Extract Preparation For E. Coli-Based Cell-Free Protein Synthesis And Rapid Site-Specific Incorporation Of Unnatural Amino Acids In Proteins, Prashanta Shrestha

Theses and Dissertations

This thesis reports the viability of E. coli cell extracts prepared using equipment that is both common to biotechnology laboratories and able to process small volume samples and expression of proteins containing unnatural amino acids (UAAs) at higher level using PCR amplified linear DNA templates (LETs) in cell-free protein synthesis (CFPS) system. E. coli-based cell extracts are a vital component of inexpensive and high-yielding CFPS reactions. However, effective preparation of E. coli cell extract is limited to high-pressure homogenizers (French press style or impinge-style) or bead mill homogenizers, which all require a significant capital investment. This work specifically assessed the …

Liquid-Liquid Equilibrium Of Biodiesel Components, Joseph C. Bell

Theses and Dissertations

Biodiesel is produced from vegetable oils through transesterification. Triglyceride mixtures extracted from oilseed feedstocks are upgraded by reaction with an alcohol in the presence of a catalyst to produce fatty acid esters. This reaction produces a mixture of esters, glycerin, alcohol, and catalyst. Separation of the fatty acid esters (biodiesel) and glycerin can be accomplished through liquid-liquid extraction by water addition. Designing liquid-liquid extraction with water as the solvent requires ternary liquid-liquid equilibrium data for mixtures of water, glycerin, and fatty acid esters. Ternary mixture LLE data have been experimentally measured for several of these systems. Those measured include mixtures …

Model Development And Application Of Molecular Simulations For The Study Of Proton Transport In Bulk Water And For The Prediction Of Dipole Moments Of Organic Compounds, Abhishek Asthana

Theses and Dissertations

The present work demonstrates the application of molecular simulations (MD) in two different areas: proton transport in bulk water and estimation of the dipole moment of polar organic compounds. In both areas, relatively few successful and robust methodologies exist. In the first part, a new polarizable water model is developed for MD simulations of the proton transport process. The model was parametrized from a combination of quantum chemical calculations and experimental water properties. The model was implemented in MD simulation studies of liquid water at room temperature, as well as with excess protons. For pure water the model gave good …

Site-Specific Metallization Of Multiple Metals On A Single Dna Origami Template, Bibek Uprety

Theses and Dissertations

This work examines the selective deposition of two different metals on the same DNA origami template for nanofabrication. DNA, with adjustable size and shape serves as a suitable template for fabricating metal junctions in the nanometer domain via bottom-up assembly. Bottom-up assembly utilizes the recognition capability of molecules like DNA to self-assemble and form structures. In this regard, DNA origami provides a useful means for forming nanostructures by folding single-stranded DNA into different two and three dimensional shapes. Selective deposition of metal on specific locations of a DNA template is essential for making DNA-templated electronic circuits.Site-specific metallization of DNA origami …

Ultrasound-Induced Phase Change Of Emulsion Droplets For Targeted Gene And Drug Delivery, James R. Lattin

Theses and Dissertations

This dissertation explores the potential of using perfluorocarbon emulsion droplets to add an ultrasound-sensitive element to drug delivery systems. These emulsion droplets may be induced to vaporize with ultrasound; during the rarefactional phase of an ultrasound wave, the pressure around the droplets may fall below the vapor pressure of the liquid forming the emulsion, providing a thermodynamic potential for vaporization. This ultrasound-induced phase change of the emulsion droplet could release therapeutics attached to the droplet surface or aid in drug delivery due to mechanical effects associated with vaporization and expansion, similar to the ability of cavitating bubbles to aid in …

Syngas Impurity Effects On Cell Growth, Enzymatic Activities And Ethanol Production Via Fermentation, Deshun Xu

Theses and Dissertations

A syngas compositional database with focus on trace impurities was established. For this work, ammonia (NH3) and benzene (C6H6) effects on cell growth, enzymatic activities of hydrogenase and alcohol dehydrogenase (ADH), and product formation were studied. NH3, after entering media, will be converted rapidly to NH4+, which will raise the total osmolarity of the media. NH3, as a common nutrient for the cell growth, is not the real culprit for cell growth inhibition. In essence, it is the high osmolarity resulting from the accumulation of NH4+ in the media which disrupts the normal regulation of the cells. It was concluded …

Thermodynamic Kinetics And Efficiency Analysis Of Methyl Viologen, Chang Chen

Theses and Dissertations

Methyl Viologen (MV) is an electron mediator that has great possibilities to be used with an electrode system in which the electrode system provides electrons towards reducing MV species. MV has three redox states and they can be converted to each other via redox reactions on the surface of the electrode. The concentration of the three species of MV was related to the voltage potential applied to the system through a thermodynamic model. With the thermodynamic model the concentration of the three species can be predicted with different applied voltage potentials towards providing guidance for controlling the redox state of …

Development Of A Method To Study Thromboembolism By Direct Observation In Blood-Contacting Microsystems Using High-Definition Video Microscopy, Yong Min Kim

Theses and Dissertations

A unique and novel method to study thromboembolism by direct observation was developed. High-definition videos of thrombus formation and embolization were successfully obtained in miniature flow cells using in-vitro, non-invasive, real-time techniques. Critical parameters of thromboembolism such as thrombus growth rate, thrombus growth direction, shear force on the thrombus at embolization, and adhesion strength of the thrombus to the foreign surface were determined. Thrombus growth was found predominantly in two locations: 1) in the flow recirculation zone just after the trailing edge of the small tubes (53%) and 2) at the leading edge of the small tubes (47%). In the …

Novel Iron Catalyst And Fixed-Bed Reactor Model For The Fischer-Tropsch Synthesis, Kyle Martin Brunner

Theses and Dissertations

This work investigates a novel iron Fischer-Tropsch (FT) catalyst preparation and describes the development of a trickle fixed-bed recycle reactor model (TFBRRM) for the FT synthesis applicable to both iron and cobalt catalysts. The iron catalyst preparation was developed using a novel solvent deficient precipitation reaction. Fifteen Fe/Cu/K/SiO2 catalysts were prepared to investigate key preparation variables including timing of promoter addition, washing or not washing after precipitation, and drying temperature. Adding promoters to starting materials before precipitation (1S) gives more uniform promoter distributions which gives higher water-gas shift activity and lower methane selectivity. Unwashed catalysts have smaller average pore and …

Schmidtea Mediterranea Planaris As A Novel Animal Model For Investigating The Dynamics Of Nervous System Development In Fetal Alcohol Spectrum Disorder, Jesse Lowe

Theses and Dissertations

Fetal Alcohol Spectrum Disorder (FASD) is a prevalent developmental disease that is caused by excess in utero exposure to ethanol. The importance of timing and dosage of ethanol has been elucidated by previous investigations conducted with humans, rodents, and other model organisms, but challenges associated with determining functional deficiencies have necessitated the introduction of a novel animal model for investigating the dynamics of FASD. In this thesis, we propose that the freshwater flatworm planarian species, Schmidtea mediterranea, has the capability to fulfill this need. Planaria have the ability to completely regenerate fragments into intact, functional animals, and in these studies, …

Understanding Noble Metal Addition In Cobalt Fischer Tropsch Catalysts, Kari Marie Cook

Theses and Dissertations

The effects of noble metal (NM) promotion and deposition order (co-deposition of NM with the final Co deposition [co-dep] or sequential deposition of NM after Co deposition [seq-dep]) on surface area, pore size, metal retention, crystallite size, noble metal distribution and bonding in Co Fischer Tropsch (FT) catalysts were studied as were the resulting Co reducibility and Fischer Tropsch activity/selectivity properties. Catalysts containing nominally 25wt% Co with either 0.3 wt% Ru, 0.58 wt% Pt, 0.55wt% Re, or no NM on a La-stabilized-Al2O3 support were prepared by wet deposition. The Co, Pt, and Re were uniformly dispersed, but Ru distribution and …

Homogeneous Viologens For Use As Catalysts In Direct Carbohydrate Fuel Cells, Dane C. Hansen

Theses and Dissertations

Deriving electrical energy from glucose and other carbohydrates under mild conditions is an important research objective because these biomolecules are abundant, renewable, and can provide 12 to 24 electrons per molecule, yielding substantial electrical power. It was previously observed that disubstituted viologens, salts of N,N'-disubstituted 4,4'-bipyridine, are able to oxidize glucose under alkaline conditions. Building on that initial result, the objective of this work was to understand and quantify the effectiveness and utility of viologens as catalysts for use in direct carbohydrate fuel cells.The extent that viologens oxidize carbohydrates, the conditions under which that oxidation occurs, and the mechanism for …

Computational Modeling Of Functionalized Carbon Nanotubes, Nathaniel Lee Miller

Theses and Dissertations

Ab initio self-consistent field (SCF) molecular orbital calculations were performed employing various basis sets to computationally predict methods to functionalize and solubilize carbon nanotubes. The structure and Restricted Hartree-Fock (RHF) or “total” energies of functionalized nanotubes of various configurations were determined via theoretical calculations. Total energies were used to determine preferences for adsorption on nanotube sur-faces. Various diameter carbon nanotubes (CNTs) were tested to determine where a transition from a non-wrapping to a wrapping approach was found likely to occur as a function of diameter. Further refinements to this method could be used to explore additional interactions as nanotube diameter …