Engineering Commons^™

Characterization, Synthesis And Stabilization Of Au Based Bimetallic Catalysis For The Hydrochlorination Of Acetylene, Kerry Charles O'Connell

Theses and Dissertations

Polyvinyl chloride (PVC) is the third most-produced plastic polymer world-wide by volume after polypropylene and polyethylene. Vinyl chloride monomer, which is polymerized into PVC, is produced via mercuric chloride catalysts that deactivate as mercury sublimes into the atmosphere from the catalyst surface, resulting in substantial environmental concerns.

In an effort to rationally synthesize non-mercuric catalysts, strong electrostatic adsorption (SEA) was used to prepare highly dispersed and active gold nanoparticles over low point of zero charge (PZC) carbon to increase the active metal surface area. The use of <1.5nm gold clusters did not lead to large increases in activity as there was an increased degree of particle coalescence during reaction for activated carbon supported samples. A pronounced support effect was observed in which oxide supports completely prevented Au sintering, but was virtually inactive. This suggests that the active site for the hydrochlorination reaction involves the carbon surface.

The stabilization of carbon supported gold nanoparticles in the HCl-rich reaction environment was …

Adsorption Reversibility Of So2, No2, And No On 13x And 5a Zeolites, Peter Fairchild

Theses and Dissertations

The adsorption reversibility of gasses that are typically found in flue gas for coal based power plants, such as SO2, NO2, and NO, onto 13X and 5A zeolites was presently investigated. The four individual gas mixtures containing these species consisted of 74 ppm NO (balance He), 74 ppm NO2 (balance He), 42 ppm SO2 (balance He), and 500 ppm SO2 (balance N2), which were also consistent with the values that are found in flue gas. Another gas, 15.03 mol% CO2 (balance N2), was also used in this work to evaluate the role of exposing SO2 to the zeolite on their …

Polyphenols As Natural, Dual-Action Therapeutics For Alzheimer's Disease, Kayla M. Pate

Theses and Dissertations

Alzheimer’s disease (AD), the most common form of dementia, is characterized by extracellular plaques in the brain created when monomeric amyloid-β (Aβ) protein aggregates into fibrillar structures. Soluble Aβ aggregates, including oligomers, that form along the reaction pathway are believed to be the primary pathogenic species and have been shown to increase the production of reactive oxygen species (ROS). This upregulation of ROS is one suggested contributing factor of Aβ aggregate cytotoxicity and has proven capable of mediating cell signaling associated with Aβ aggregate-induced cellular responses.

Polyphenols have been suggested as a complimentary AD therapeutic based on epidemiological evidence that …

Development Of Pressure Swing Adsorption (Psa) Processor Co2 Capture From Flue Gas, Md. Atikur Rahman

Theses and Dissertations

Reducing the anthropogenic CO2 emissions and lowering the concentration of greenhouse gases in the atmosphere has become one of the most important environmental issues of recent times. To this end, the development of a cost effective pressure swing adsorption (PSA) process, utilizing commercially available 13X zeolite as the adsorbent, is underway to remove and concentrate CO2 in the flue gas of a coal-fired power plant. This systematic development effort has been carried out so far at the bench scale. It has included the following studies that defined and validated this PSA process both experimentally and via a PSA process model. …

Ultrathin Microporous Metal Oxide Coatings: Preparation By Molecular Layer Deposition, Characterization And Application, Zhuonan Song

Theses and Dissertations

Molecular layer deposition (MLD), a gas phase deposition technique, was applied to deposit conformal organic-inorganic hybrid coatings by conducting a series of sequential, self-limiting surface reactions on substrates with exquisite thickness control at the sub-nanometer level. Obtained organic-inorganic hybrid coatings can subsequently be converted into porous coatings by removing the organic compound. Potential of functional coatings and membranes prepared by MLD was explored for applications from adsorptive separation, water purification, to gas storage.

We demonstrated a new concept, pore misalignment, to continuously fine tune the molecular-sieving “gate” of 5A zeolite by adjusting the external porous Al2O3 MLD coating thickness. For …

Pvdf Membranes With Stable, Ultrathin Graphene Oxide (Go) Functional Coatings For Antifouling Oil/Water Separation Under Cross-Flow Condition, Lei Wang

Theses and Dissertations

Oil/water separation plays an important role in industrial wastewater treatment and environment protection. For the treatment of oily wastewater, especially for removing oil droplets with sizes in the micrometer range, ultrafiltration (UF) membrane technology is considered the most efficient method due to its high separation efficiency and relatively simple operational process. However, caused by the deposition of the oil droplets onto the membrane surface and into the membrane pores, the fouling of UF membranes shortens their service time and degrades their separation performance in practical applications.

In this work, graphene oxide (GO) was utilized as a novel coating material to …

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 …

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 …

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 …

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 …

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 …

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, …

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 …

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 …

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 …

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 …