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Articles 3331 - 3360 of 14131
Full-Text Articles in Engineering
A Reduced-Order Lumped Model For Li-Ion Battery Packs During Operation, Paul T. Coman, Eric C. Darcy, Brad Strangways, Ralph E. White
A Reduced-Order Lumped Model For Li-Ion Battery Packs During Operation, Paul T. Coman, Eric C. Darcy, Brad Strangways, Ralph E. White
Faculty Publications
Modeling heat distribution in Li-ion battery packs can be challenging, especially if the battery pack is large and the cells are operated at high C-rates, which usually requires high-order physics-based mathematical models. Reduced and simplifying models can, however, be used at lower rates. This paper presents a fast novel reduced lumped model (RLM) that can be used to calculate the temperature increase during the high-current discharge of cylindrical Li-ion cells in a subscale of a battery pack. By reducing the PDE utilized to calculate the state of charge (SoC) to ODE's and solving them analytically, the reduced model can be …
Solvent-Free Solid-State Lithium Battery Based On Lifepo₄ And Mwcnt/Peo/Pvdf-Hfp For High-Temperature Applications, Han Yu, Ye Jin, Guodong David Zhan, Xinhua Liang
Solvent-Free Solid-State Lithium Battery Based On Lifepo₄ And Mwcnt/Peo/Pvdf-Hfp For High-Temperature Applications, Han Yu, Ye Jin, Guodong David Zhan, Xinhua Liang
Chemical and Biochemical Engineering Faculty Research & Creative Works
Rechargeable lithium-ion batteries (LIBs) have a wide range of applications but face challenges in harsh working or operating environments at high temperatures. In this work, a solid polymer electrolyte with MWCNT-COOH as an additive (MWCNT-SPE) was obtained. MWCNT-SPE has a high thermal stability and can be used in high-temperature operating environments. Solid-state lithium batteries based on MWCNT-SPE and LiFePO4 were assembled. The resulting lithium batteries exhibited excellent electrochemical properties at 70 and 120 °C, demonstrating a wide range of operations suitable for solid-state batteries with extreme demands. The symmetrical Li/MWCNT-SPE/Li cell operated for 1800 h with low polarization voltage …
Raman Investigations Of The Radiation-Induced Modifications In Ipp-Vgcnf Nanocomposites: The Nanofillers’ Tale, Dorina M. Chipara, Mihail Secu, Karen Lozano, Corina Secu, Mircea Chipara
Raman Investigations Of The Radiation-Induced Modifications In Ipp-Vgcnf Nanocomposites: The Nanofillers’ Tale, Dorina M. Chipara, Mihail Secu, Karen Lozano, Corina Secu, Mircea Chipara
Physics & Astronomy Faculty Publications
Nanocomposites of isotactic polypropylene loaded by various amounts of vapor-grown carbon nanotubes ranging from 0 to 20% wt. were obtained by extrusion. Raman investigations on these nanocomposites are reported. The nanocomposites were irradiated using a 60Co, with an integral dose of 1 kGy/h up to integral doses of 9 kGy, 18 kGy, and 27 kGy, in air, at room temperature. Raman measurements were performed by using a Bruker Senterra confocal Raman spectrometer operating at 785 nm. The research is focused on the information contained within the D and G Raman lines of these nanocomposites as a function of nanotube loading …
Recent Advances In Silver Nanoparticle-Based Electrochemical Sensors For Determining Organic Pollutants In Water, Ziad Khalifa, Moustafa Zahran, Magdy Zahran, Magdi Abdelazzem
Recent Advances In Silver Nanoparticle-Based Electrochemical Sensors For Determining Organic Pollutants In Water, Ziad Khalifa, Moustafa Zahran, Magdy Zahran, Magdi Abdelazzem
Chemical Engineering
Water pollutants have attracted great attention because of their negative effect on human health. Accordingly, various analytical techniques have been investigated to detect water pollutants as a preliminary step for their control. This review highlights silver nanoparticles (AgNPs) as promising electrochemical probes studied for detecting organic pollutants. Electrochemical sensors can be fabricated by modifying electrode surfaces using AgNPs via different techniques, such as electrochemical deposition, drop casting, spin coating, sticking, and transfer sticking, as well as carbon paste-based modification. AgNPs at electrode surfaces can be identified by their stripping to form Ag+ with a particular oxidation peak. Additionally, they can …
Open Source Software Toolchain For Automated Non‐Targeted Screening For Toxins In Alternative Foods, S. W. Breuer, L. Toppen, S. K. Schum, J. M. Pearce
Open Source Software Toolchain For Automated Non‐Targeted Screening For Toxins In Alternative Foods, S. W. Breuer, L. Toppen, S. K. Schum, J. M. Pearce
Michigan Tech Publications, Part 1
Previous published methods for non-targeted screening of toxins in alternative foods such as leaf concentrate, agricultural residues or plastic fed to biological consortia are time consuming and expensive and thus present accessibility, as well as, time-constraint issues for scientists from under resourced settings to identify safe alternative foods. The novel methodology presented here, utilizes a completely free and open source software toolchain for automatically screening unknown alternative foods for toxicity using experimental data from ultra-high-pressure liquid chromatography and mass spectrometry. The process uses three distinct tools (mass spectrometry analysis with MZmine 2, formula assignment with MFAssignR, and data filtering with …
Fischer–Tropsch Synthesis: Effect Of The Promoter’S Ionic Charge And Valence Level Energy On Activity, Mirtha Z. Leguizamón León Ribeiro, Joice C. Souza, Muthu Kumaran Gnanamani, Michela Martinelli, Gabriel F. Upton, Gary Jacobs, Mauro C. Ribeiro
Fischer–Tropsch Synthesis: Effect Of The Promoter’S Ionic Charge And Valence Level Energy On Activity, Mirtha Z. Leguizamón León Ribeiro, Joice C. Souza, Muthu Kumaran Gnanamani, Michela Martinelli, Gabriel F. Upton, Gary Jacobs, Mauro C. Ribeiro
Center for Applied Energy Research Faculty and Staff Publications
In this contribution, we examine the effect of the promoter´s ionic charge and valence orbital energy on the catalytic activity of Fe-based catalysts, based on in situ synchrotron X-ray powder diffraction (SXRPD), temperature-programmed-based techniques (TPR, TPD, CO-TP carburization), and Fischer–Tropsch synthesis catalytic testing studies. We compared the promoting effects of K (a known promoter for longer-chained products) with Ba, which has a similar ionic radius but has double the ionic charge. Despite being partially “buried” in a crystalline BaCO3 phase, the carburization of the Ba-promoted catalyst was more effective than that of K; this was primarily due to its …
Open-Ended Hollow Coaxial Cable Resonator Sensor, Jie Huang, Chen Zhu, Rex E. Gerald Ii
Open-Ended Hollow Coaxial Cable Resonator Sensor, Jie Huang, Chen Zhu, Rex E. Gerald Ii
Electrical and Computer Engineering Faculty Research & Creative Works
An open-ended hollow coaxial cable resonator probe configured to receive an aerosol sample for analysis. A metal post shorts the resonator's inner and outer conductors. A metal plate is spaced apart from an open end of the resonator by a dielectric layer that contains the received aerosol sample. Interrogator circuitry coupled to the resonator transmits an electromagnetic wave within the resonator and generates an electric field at the open end of the resonator. The interrogator circuitry is responsive to the generated electric field for determining a resonance frequency and an impedance of the resonator when the aerosol sample is present …
Rotary Furnace Lining To Reduce Thermal Stress, Zamira Mukhamedbaeva, Erkin Kurbanov, Abduvali Mukhamedbaev
Rotary Furnace Lining To Reduce Thermal Stress, Zamira Mukhamedbaeva, Erkin Kurbanov, Abduvali Mukhamedbaev
CHEMISTRY AND CHEMICAL ENGINEERING
The aim of the study is to reduce the thermal stresses of the lining in the areas adjacent to the flare sintering zone of rotary kilns intended for the production of cement clinker. It is proposed to use a lining made of parallel rows of alternating chamotte and chromium-magnesite refractory products to reduce thermal stresses in the areas adjacent to the flare sintering zone by up to 20%, increase the service life of the lining by 1.1-1.2 times as a result of equalizing thermal stresses in the areas of the sintering zone. Optimization of the initial raw material mixture, in …
Computer Simulation Of Particle Velocity In A Cyclone, Askar Artikov, Botir Usmonov, Dilshod Karabaev, Anvar Ulmasbaev, Lola Akabirova
Computer Simulation Of Particle Velocity In A Cyclone, Askar Artikov, Botir Usmonov, Dilshod Karabaev, Anvar Ulmasbaev, Lola Akabirova
CHEMISTRY AND CHEMICAL ENGINEERING
The article sets the goal of determining and calculating the speed of accelerated movement of particles in the gas-dust flow of an air cyclone, depending on the size of the cyclone, the physical properties of the particle and the gas-dust flow. A method for constructing a computer model of the motion of a particle in a roaring gas-dust flow of a cyclone is presented. The sequence of formalization of the computer model of the process of sedimentation of particles of a gas-dust flow of a cyclone unit is based on the theoretical foundations of aerodynamics and touches on the most …
Anti-Corrosion Protection Of Metal Parts Of Transportation Equipment With A Polymer Coating Based On Epoxiurethane, Aida Barkhanadjyan, Ravshan Khakimov, Botir Ibragimov, Oybek Vafayev, Dmitriy Ayrapetov
Anti-Corrosion Protection Of Metal Parts Of Transportation Equipment With A Polymer Coating Based On Epoxiurethane, Aida Barkhanadjyan, Ravshan Khakimov, Botir Ibragimov, Oybek Vafayev, Dmitriy Ayrapetov
CHEMISTRY AND CHEMICAL ENGINEERING
Automotive vehicles are constantly exposed to corrosion processes, and the durability of metal parts depends on the intensity of corrosion. The loss of metals from corrosion is 8-10% of the initial metal mass. In total, losses from corrosion are 4-6% of national income in many countries. This indicates the need for research and the importance of scientific and technical work in this area. This can be achieved by developing a technology for producing anticorrosive compounds and applying them as protective coatings. The anticorrosive protection of a coating synthesized on the basis of local raw materials - epoxyurethane with an additive …
Synthesis And Research Of Silicon-Containing Phthalocyanine, Dilmurod Shukurov, Hayit Turayev, Abdulakhat Djalilov, Masud Karimov
Synthesis And Research Of Silicon-Containing Phthalocyanine, Dilmurod Shukurov, Hayit Turayev, Abdulakhat Djalilov, Masud Karimov
CHEMISTRY AND CHEMICAL ENGINEERING
The aim of this study is to synthesize, and study a new form of dye based on phthalocyanine, a silicon-containing phthalocyanine pigment used as a dye for dye-sensitive solar cells, which are currently third generation solar cells as one of the energy source alternatives. To achieve this goal, a silicon-containing phthalocyanine pigment containing urea, phthalic anhydride and sodium fluorosilicate was synthesized and studied. Based on the results of IR spectroscopy, the reaction of pigment formation is proposed and the data of scanning electron microscopy is presented. Its differential thermal analysis, photodynamic analysis and its relationship with inorganic and organic solvents …
Asphaltene Thermodynamic Flocculation During Immiscible Nitrogen Gas Injection, Mukhtar Elturki, Abdulmohsin Imqam
Asphaltene Thermodynamic Flocculation During Immiscible Nitrogen Gas Injection, Mukhtar Elturki, Abdulmohsin Imqam
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Gas-enhanced oil recovery is one of the most advantageous enhanced oil recovery methods. Nitrogen is one of the most investigated gases because of its beneficial properties. However, during its interaction with crude oil, nitrogen can induce asphaltene deposition, which may result in severe formation damage and pore plugging. Few works have investigated the impact of nitrogen on asphaltene instability. This research studied the immiscibility conditions for nitrogen in nanopores and the impact of nitrogen on asphaltene precipitations, which could lead to plugging pores and oil recovery reduction. A slimtube was used to determine the minimum miscibility pressure (MMP) of nitrogen …
Effect Of Addition Of Nano Silicon Dioxide To Cement Bricks: Preparation And Characterictics, Rehab Emad, Ibrahim M. Ibrahim, M. A. Radwan, M. A. Sadek, Hany A. Elazab
Effect Of Addition Of Nano Silicon Dioxide To Cement Bricks: Preparation And Characterictics, Rehab Emad, Ibrahim M. Ibrahim, M. A. Radwan, M. A. Sadek, Hany A. Elazab
Chemical and Biochemical Engineering Faculty Research & Creative Works
The aim of the research is to design and produce a durable, and high load, bearing build constructing bricks based on cement, sand, and aggregates with the addition of Nano silica, studying the effect of the added materials to get a background about the impact of the Nano silica on the ability of using such a product. The cement used is 52.5 grade which represent the strength of the cement, sand with particle size 300-600 micrometer, aggregates with diameter lays between 0.5-1 cm better to use smaller size, water, and finally Nano-silica with particle size 17 nm with purity higher …
Self-Adhesive Silicone Microstructures For The Treatment Of Tympanic Membrane Perforations, Gabriela Moreira Lana, Katharina Sorg, Gentiana Ioana Wenzel, Dietmar Hecker, René Hensel, Bernhard Schick, Klaus Kruttwig, Eduard Arzt
Self-Adhesive Silicone Microstructures For The Treatment Of Tympanic Membrane Perforations, Gabriela Moreira Lana, Katharina Sorg, Gentiana Ioana Wenzel, Dietmar Hecker, René Hensel, Bernhard Schick, Klaus Kruttwig, Eduard Arzt
Chemical and Biochemical Engineering Faculty Research & Creative Works
Inspired by the gecko foot, polymeric microstructures have demonstrated reliable dry adhesion to both stiff objects and sensitive surfaces such as skin. Microstructured silicone patches are proposed, herein, for the treatment of tympanic membrane perforations with the aim of serving as an alternative for current surgical procedures that require anesthesia and ear canal packing. Sylgard 184 PDMS micropillars of 20 μm in diameter and 60 μm in length are topped by a Soft Skin Adhesive (SSA) MG7-1010 terminal layer, of about 25 μm thickness. The adhesion is evaluated by specially designed tack tests against explanted murine eardrums and, for comparison, …
Understanding The Plugging Performance Of Hpam-Cr (Iii) Polymer Gel For Co2 Conformance Control, Xindi Sun, Baojun Bai, Ali Khayoon Alhuraishawy, Daoyi Zhu
Understanding The Plugging Performance Of Hpam-Cr (Iii) Polymer Gel For Co2 Conformance Control, Xindi Sun, Baojun Bai, Ali Khayoon Alhuraishawy, Daoyi Zhu
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
With the demand for conformance control in carbon dioxide (CO2) flooding fields, hydrolyzed polyacrylamide-chromium [HPAM-Cr (III)] polymer gel has been applied in fields for CO2 conformance control. However, the field application results are mixed with success and failure. This paper is intended to understand the HPAM-Cr (III) polymer gel plugging performance in CO2 flooding reservoirs through laboratory experiments and numerical analysis. We conducted core flooding tests to understand how the cycles of CO2 and water affect the HPAM-Cr (III) polymer gel plugging efficiency to CO2 and water during a water-alternating-gas (WAG) process. Berea Sandstone …
Cement Bricks Based On Shredded Automobile Tires, Nour Waheed, Ibrahim M. Ibrahim, M. A. Radwan, M. A. Sadek, Hany A. Elazab
Cement Bricks Based On Shredded Automobile Tires, Nour Waheed, Ibrahim M. Ibrahim, M. A. Radwan, M. A. Sadek, Hany A. Elazab
Chemical and Biochemical Engineering Faculty Research & Creative Works
The essential target of this is to make good, qualified bricks with economic background and to have several uses than ordinary brick that is utilized in construction of homes or any building. From these useful properties of those blocks are acoustic segregation and thermal insulation also with recovery of many wastes that don’t be benefit from them; create from them jobs to be reused and to make brick economically wise and to be applied for example the insulation. From those squandering, are the shredded used tires after being used and it can’t be used anymore. It was cleared that the …
Cochlear Inflammaging In Relation To Ion Channels And Mitochondrial Functions, Parveen Bazard, Jennifer Pineros, Robert D. Frisina, Mark A. Bauer, Alejandro A. Acosta, Lauren R. Paganella, Dominika Borakiewicz, Mark Thivierge, Freyda L. Mannering, Xiaoxia Zhu, Bo Ding
Cochlear Inflammaging In Relation To Ion Channels And Mitochondrial Functions, Parveen Bazard, Jennifer Pineros, Robert D. Frisina, Mark A. Bauer, Alejandro A. Acosta, Lauren R. Paganella, Dominika Borakiewicz, Mark Thivierge, Freyda L. Mannering, Xiaoxia Zhu, Bo Ding
Chemical and Biochemical Engineering Faculty Research & Creative Works
The slow accumulation of inflammatory biomarker levels in the body—also known as inflammation—has been linked to a myriad of age-related diseases. Some of these include neurodegenerative conditions such as Parkinson's disease, obesity, type II diabetes, cardiovascular disease, and many others. Though a direct correlation has not been established, research connecting age-related hearing loss (ARHL)—the number one communication disorder and one of the most prevalent neurodegenerative diseases of our aged population—and inflammation has gained interest. Research, thus far, has found that inflammatory markers, such as IL-6 and white blood cells, are associated with ARHL in humans and animals. Moreover, studies investigating …
Experimental Data On Water Soluble Polymers Thermal And Hydrolytic Stability, Reactivity Ratios Of Monomers And Frr Calculation For Thermally Stable Preformed Particle Gels Therefrom, Buddhabhushan Salunkhe, Thomas P. Schuman, Ali Al Brahim, Baojun Bai
Experimental Data On Water Soluble Polymers Thermal And Hydrolytic Stability, Reactivity Ratios Of Monomers And Frr Calculation For Thermally Stable Preformed Particle Gels Therefrom, Buddhabhushan Salunkhe, Thomas P. Schuman, Ali Al Brahim, Baojun Bai
Chemistry Faculty Research & Creative Works
Experimental data on water soluble polymer thermal and hydrolytic stability in acidic, neutral and basic pH conditions in aqueous solution is presented. Thermal and hydrolytic stability of polymer aqueous solutions were monitored in variable pH medium by aging at 130 °C temperature for different aging time. Polymer viscosity measurements were performed periodically for 3 months. Furthermore, this data can serve as a basis of monomer selection for thermally stable hydrogels for applications like oil recovery, hydrogel coatings for steam sterilized medical devices and other applications. Reactivity ratios were determined for monomers associated to the most stable polymers using 1H …
Mathematical Model For Sei Growth Under Open-Circuit Conditions, Wei Shang
Mathematical Model For Sei Growth Under Open-Circuit Conditions, Wei Shang
Theses and Dissertations
An irreversible capacity loss will take place in lithium ions batteries due to the solid electrolyte interface (SEI) creating, which consumes the active lithium and reduces solvent. SEI is either good since it can prevent further electrolyte decomposition or bad for lessening batteries' lifetime. Mathematical modeling of SEI formation is done within a porous electrode to model an empirical battery in the x-direction.A solid electrolyte interphase (SEI) growth model is developed in a mixed-mode which contains solvent diffusion through the SEI layer and its corresponding kinetics of solvent reduction at the electrode surface. The governing equations are numerically solved by …
Structure And Stability Of Ag-Ir Bimetallic Catalysts Prepared By Electroless Deposition And Synthesis And Performance Of High Selectivity Movnbsbteox Mixed Oxides For Oxidative Dehydrogenation Of Ethane, Mozhdeh Parizad
Theses and Dissertations
Improvements in industrial thermal conversions can be realized through comprehensive catalytic studies, where enhanced catalyst stability and activity are desired. Catalyst performance can be greatly affected by structural changes at high temperatures. In the case of supported Ag-Ir particles, the surface free energy (SFE) can determine preferred arrangement of the component metals. The well-established methods of strong electrostatic adsorption (SEA) and electroless deposition (ED) have been used to synthesize highly-dispersed Ag/Ir on different alumina supports (δ,θ-Al2O3 and γ-Al2O3). Surface thermodynamics dictate that the Ir-Ag system should conform to minimize free energy resulting in a low SFE Ag layer localized on …
Development Of A Multi-Scale Mechano-Electrochemical Battery Model, Drew J. Pereira
Development Of A Multi-Scale Mechano-Electrochemical Battery Model, Drew J. Pereira
Theses and Dissertations
As the automotive industry moves towards large format electric vehicles, such as trucks and SUVs, the need for highly efficient, energy-dense electrodes rapidly increases. Several promising active materials have been studied and proposed, however, many of these materials undergo significant volume change upon lithiation and de-lithiation. Cell and pack designers struggle to understand and predict how active material volume change at the particle scale will affect mechano-electrochemical behavior on the electrode, cell, and pack scales. Additionally, many of these active materials suffer in their cycle life due to a mechanically-driven degradation of the electrode matrix. Therefore, the focus of this …
Quantifying And Elucidating The Effect Of Co2 On Aemfcs, Yiwei Zheng
Quantifying And Elucidating The Effect Of Co2 On Aemfcs, Yiwei Zheng
Theses and Dissertations
Anion exchange membrane fuel cells (AEMFCs) have recently received significant attention as a future high efficiency, environmentally friendly energy conversion device. This attention is due to the potential advantages that AEMFCs can offer compared the much more common, and commercialized, proton exchange membrane fuel cells (PEMFCs) – most notably lower cost. However, there are several remaining roadblocks for the AEMFC technology to be widely adopted, such as: i) the stability of the anion exchange membranes (AEMs) and anion exchange ionomer (AEIs); ii) the development of highly active catalysts with either low platinum group metal (PGM) loading or catalysts that are …
Recent Advances In Catalytic Ethylene Epoxidation: Synthesis, Characterization, And Evaluation, Benjamin Thomas Egelske
Recent Advances In Catalytic Ethylene Epoxidation: Synthesis, Characterization, And Evaluation, Benjamin Thomas Egelske
Theses and Dissertations
First synthesized in 1859 by French chemist Charles-Adolphe Wurtz, ethylene oxide (EO) is produced from the direct epoxidation of ethylene and molecular oxygen over a low surface area α-Al₂O₃ supported silver (Ag) catalyst [1-6]. With a production capacity over 35 Mt/year, EO is the largest chemical by volume synthesized from a heterogeneously catalyzed process and is used in the production of ethylene glycol, ethoxylates, and ethanolamines [6, 7]. State-of-the-art catalyst formulations contain high loadings of Ag, typically 12-30wt%, required to recover activity in the presence of promoter elements which increase EO selectivity from ~75% for unsupported Ag to 80% for …
Hydrodeoxygenation Of Biomass Derived Sugar Alcohols To Platform Chemicals Using Heterogeneous Catalysts, Blake Macqueen
Hydrodeoxygenation Of Biomass Derived Sugar Alcohols To Platform Chemicals Using Heterogeneous Catalysts, Blake Macqueen
Theses and Dissertations
This work set out to investigate biomass derived sugar alcohol upgrading via the removal of oxygen and hydroxyl groups via the hydrodeoxygenation reaction utilizing heterogeneous catalysts. The importance of reaction conditions, catalyst meal loadings, catalyst structure and properties were probed using techniques such as design of experiments, and spectroscopic techniques including Raman and DRIFTS. The state of the art simultaneous hydrodeoxygenation (S-HDO) catalyst ReOx-Pd/CeO2 was investigated and optimized for various sugar alcohol substrates. The kinetics and associated mass transfer were also investigated to give further insight into the reaction over the ReOxPd/CeO2 catalyst.
First, …
Catalytic And Non-Catalytic Methods For Hydrocarbon Upgrading, Valorization, And Pollutant Control, Michael Morgan Royko
Catalytic And Non-Catalytic Methods For Hydrocarbon Upgrading, Valorization, And Pollutant Control, Michael Morgan Royko
Theses and Dissertations
This work investigates catalytic and non-catalytic oxidative chemical upgrading and pollutant remediation techniques to responsibly utilize hydrocarbon feedstocks with existing infrastructure as the transition to more renewable and cleaner feedstocks for energy generation are developed. These technologies include oxidative dehydrogenation of ethane, development of magnetically separable catalysts to reduce carbon monoxide emissions during biomass upgrading as well as the subsequent use of the upgraded biomass for partial coal replacement, and electrochemical treatment of a washcoat free wire mesh supported catalyst to reduce carbon monoxide emissions in combustion exhaust.
First, doping of secondary metals in M1/M2 catalysts for oxidative dehydrogenation of …
Insights Into Rational Catalysts Synthesis, Abolfazl Shakouri
Insights Into Rational Catalysts Synthesis, Abolfazl Shakouri
Theses and Dissertations
Atomically distributed metal centers with maximized atom utilization efficiency called single-atom catalysts (SACs) have attracted significant attention in catalysis. SACs with the advantages of both homogeneous and heterogeneous catalysts have been rising as a new frontier in the field of catalysis. New catalytic technologies are ever-growing, considering 90% of all chemical processes employ catalysts, securing modern society’s sustainable future. A classical field in catalysis has been dedicated to catalysis by supported metals. Recently, a vast effort has been devoted to smaller catalyst particles where size is restricted to a single atom on a surface. Single atoms supported or embedded on …
Shape-Selective Silver Catalysts For Ethylene Epoxidation, Kaveh Shariati
Shape-Selective Silver Catalysts For Ethylene Epoxidation, Kaveh Shariati
Theses and Dissertations
Epoxidation of ethylene with oxygen over promoted silver catalyst is one of the most important examples of heterogeneous catalysis to date with a multi-billion dollar annual market. Ethylene oxide (EO) can be used directly as a sterilizer, disinfectant, and fungicide, or as an intermediate chemical for producing ethylene glycol, detergents, antifreeze, polyesters, as well as a variety of other commercial chemicals. Thus, ethylene oxide is known as one of the highest volume chemicals produced in the chemical industry, accounting for approximately 40-50% of the total value of organic chemicals produced by heterogeneous oxidation. Considering the application of EO in detergents …
Preparation, Characterization And Evaluation Of Rationally Designed Catalysts By Electroless Deposition, Wen Xiong
Theses and Dissertations
In heterogeneous catalysis, it is a proven factor that the surface-specific activity and the catalyst selectivity strongly depends on the active sites which are determined by the composition, size, and shape of the particle. For structure-sensitive reactions favored by specific surface sites, such as corners, steps, or edges, TOF and selectivity can be greatly changed by the size of catalyst particles since the active site distribution will change with the size of the catalysts. Usually, metal particles are synthesized by two methods in industry, namely precipitation and impregnation, which often exhibit a broad size distribution. The grand challenge of colloidal …
Fine Points For Broad Bumps: The Extension Of Rietveld Refinement For Benchtop Powder Xrd Analysis Of Ultra-Small Supported Nanoparticles, Jeremiah W. Lipp
Fine Points For Broad Bumps: The Extension Of Rietveld Refinement For Benchtop Powder Xrd Analysis Of Ultra-Small Supported Nanoparticles, Jeremiah W. Lipp
Theses and Dissertations
The goal of this work is to demonstrate the capabilities of benchtop Bragg diffraction in characterizing ultra-small (< 2nm) nanoparticles. To this end we have established a method for accurately separating the background, adjusting for relevant intensity effects, and analyzing the results with Rietveld refinement. This method is applied to the characterization of six silica-supported “noble” metals under ambient conditions: Pt, Pd, Ir, Rh, Ru, and Au. Surprisingly, Bragg diffraction is capable of shining light on this difficult-to-characterize size region – revealing the propensity of these metal nanoparticles to oxidize at room temperature. Preliminary findings for future work are also discussed: extending our method to crystalline supports and fluorescent samples.
From The Surface To The Reactor: Identifying The Active Sites For Propane Dehydrogenation On Platinum-Based Catalysts Through Density Functional Theory, Experimental Data, And Uncertainty Quantification, Charles Henry Fricke
Theses and Dissertations
Propane dehydrogenation is a critical process of producing propylene, an important feedstock for the chemical industrial. There are multiple key processes to produce propylene in this manner, but one of the largest processes involves non-oxidative dehydrogenation on a platinum-tin alloy based catalyst. In general, these reactions and catalytic particles are complex, with many dehydrogenation, cracking, and reforming reactions taking place during these processes on multiple surfaces. With this in mind, ab initio computational catalysis models are used to generate further insight into these catalytic processes. In this dissertation, there are three aims to be solved: identifying the most likely active …