Chemical Engineering Commons^™

X-Ray Absorption Spectroscopy Applied To Mixed-Metal Iron-Based Fischer-Tropsch Catalysts, Andrew Allen Campos

LSU Doctoral Dissertations

Synthetic fuels derived from methane, coal or biomass are essential in addressing future transportation fuel demands which are expected to exceed petroleum-derived capacities. The Fischer-Tropsch synthesis (FTS) is the most studied technique for the conversion of coal or biomass-derived syngas into transportation fuels. Fe-based catalysts are typically used for the FTS of biomass and/or coal-derived syngas due to: the relatively low cost of iron, water-gas shift activity, and low methane selectivity at industrial FTS conditions. Fe/Cu/SiO2 Fischer-Tropsch catalysts promoted with Cr, Mn, Mo, W, or Zr were studied in-situ, using Fe K-edge TPR XANES (temperature programmed reduction X-ray absorption near-edge …

Mesoporous Tin Oxide As An Oxidation-Resistant Catalyst Support For Proton Exchange Membrane Fuel Cells, Peng Zhang, Sheng-Yang Huang, Branko N. Popov

Faculty Publications

Mesoporous catalyst support based on tin oxide (SnO₂) is synthesized with high surface area of 205 m² g⁻¹ and with narrow pore size distribution. Modified polyol method is used to deposit platinum on SnO₂. The physical properties of the support and the SnO₂-supported Pt catalyst (Pt/SnO₂) are characterized by using the Brunauer, Emmett, and Teller method, X-ray diffraction, and transmission electron microscopy. The electrochemical stability and durability of the Pt/SnO₂ catalyst are investigated by the accelerated stress tests proposed by the U.S. Department of Energy. Pt/SnO₂ catalyst exhibits …

Preparations Of Composite Electrodes Of Pt With HXWo3 And Catalytic Activity Toward Oxygen Reduction Reaction, Pan-Pan Guo, You-Ju Huang, Hong-Yan Yang, Wei Li, Qing-Long Zhang, Wei-Shan Li

Journal of Electrochemistry

Three composite electrodes of platinum with hydrogen tungsten bronze(H_xWO₃)were prepared by voltammetry: hydrogen tungsten bronze deposited on platinum(H_xWO₃/Pt);platinum deposited on hydrogen tungsten bronze(Pt/H_xWO₃) and codeposited platinum and hydrogen tungsten bronze(Pt-H_xWO₃).The eletro-catalytic activities of three electrodes toward oxygen reduction reaction were studied.It is found that the catalytic activity of platinum can be improved by introducing with hydrogen tungsten bronze.Among these composite electrodes Pt/H_xWO₃,and the electrode shows the best eletro-catalytic activity toward oxygen reduction reaction,hence,provides a new way for reducing loading of …

Microkinetic Model Of Fischer-Tropsch Synthesis On Iron Catalysts, Uchenna Prince Paul

Theses and Dissertations

Fischer-Tropsch synthesis (FTS), developed in the early 1900's, is defined as the catalytic conversion of H2 and CO to hydrocarbons and oxygenates with the production of H2O and CO2. Accurate microkinetic modeling can in principle provide insights into catalyst design and the role of promoters. This work focused on gaining an understanding of the chemistry of the kinetically relevant steps in FTS on Fe catalyst and developing a microkinetic model that describes FTS reaction kinetics. Stable Al2O3-supported/promoted (20% Fe, 1% K, 1% Pt) and unsupported Fe (99% Fe, 1% Al2O3) catalysts were prepared and characterized. Transient experiments including temperature programmed …

Modeling Of Trickle-Bed Reactors With Exothermic Reactions Using Cell Network Approach, Jing Guo, Yi Jiang, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

One-Dimensional (1D) and Two-Dimensional (2D) Cell Network Models Were Developed to Simulate the Steady-State Behavior of Trickle-Bed Reactors Employed for the Highly Exothermic Hydrotreating of Benzene. the Multiphase Mass Transfer-Reaction Model and Novel Solution Method Are Discussed in This Report. the 1D Model Was Shown to Satisfactorily Simulate the Axial Temperature Field Observed Experimentally for Multiphase Flow with Exothermic Reactions. the 2D Reactor Modeling Provided Valuable Information About Local Hot Spot Behavior within the Multiphase Reactor, Identifying Situations in Which Hot Spots May Form. the Model Took into Consideration the Heterogeneous Nature of Liquid Distribution, Including Radial Liquid Maldistribution and …

Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez

All Dissertations

Biodiesel, defined as 'a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats', is finding favor commercially worldwide. The objective of this study is to evaluate the use of solid catalysts for triglyceride transesterification and carboxylic acid esterification to produce biodiesel fuel.
Processes using mainly homogeneous alkali catalysts (such as NaOH, KOH, and methoxides) have been shown to be effective for biodiesel synthesis when dealing with virgin oil feedstocks. Use of acid catalysts (e.g., H2SO4) becomes important when processing low quality feedstocks that contain appreciable amounts of free fatty acids, such as …

Catalytic Partial Oxidation Reforming Of Jp8 And S8, Thomas G. Howell

Theses and Dissertations

Catalytic partial oxidation (CPOX) reforming experiments were performed using a 10 kW Aspen Products Group, Inc. fuel processing prototype utilizing military logistic fuels JP8 and S8. S8 is a sulfur-free Fisher-Tropsch fuel, while JP8 is a multi-fuel blend, which could impact reforming efficiency, product distribution and byproduct production. Sulfur contained within the JP8 will adversely affect the product distribution; therefore, desulfurization beds, capable of removing up to 1000 ppm sulfur, were incorporated into the system. The catalyst used in the prototype is noble metal dispersed on cordierite monolith. The goal of this experiment was to evaluate the efficiency and product …

Development Of Method For Synthesis Of Pt–Co Cathode Catalysts For Pem Fuel Cells, Xuguang Li, Héctor R. Colón-Mercado, Gang Wu, Jong-Won Lee, Branko N. Popov

Faculty Publications

A procedure was developed to synthesize a platinum–cobalt (Pt–Co) alloy electrocatalyst for oxygen reduction using Co/C composite as a support. The Pt–Co/C catalysts were synthesized through: (i) chemical oxidation of carbon black, (ii) Co deposition on the oxidized carbon using a chelation method, (iii) chemical treatment in an acidic medium to remove excess of Co on the carbon surface, (iv) Pt deposition onto the Co/C support, and (v) postheat treatment to form the Pt–Co alloy catalyst. The synthesized Pt–Co/C catalyst showed improved activity and long-term stability in polymer electrolyte membrane …

Generation Of Biomarkers From Anthrax Spores By Catalysis And Analytical Pyrolysis, Phillip R. Smith

Theses and Dissertations

Anthrax spores, in weaponized form, are dangerous biological warfare agents. Handheld technology for the rapid detection of anthrax is greatly needed to improve national security. Methods to detect anthrax spores are diverse, with most taking at least an hour for positive identification. A viable option for rapid detection is analytical pyrolysis (AP), which produces chemicals containing taxonomical information (biomarkers). AP methods are reviewed and critically analyzed to show that reproducible detection of anthrax spores in a rapid manner (< 5 min) with a handheld device is not currently possible. A promising alternative to AP is the use of a catalyst to produce biomarkers from anthrax spores with improved selectivity and reproducibility. Catalytic materials having promise for this include platinum, nickel, and superacids. Experiments evaluating several of these materials are described. A biomarker mass spectral library was created, based on information available in the scientific literature, to facilitate analysis and identification of the biomarkers produced experimentally. The RAMFAC algorithm was used to deconvolute chromatographic peaks to produce clean mass spectra and match them against entries in the biomarker library. While the library is not complete, its use with the RAMFAC algorithm enabled detection of many important biomarkers in experiments involving catalytic breakdown of anthrax spores. Experimental results from preliminary tests of several catalysts are presented and discussed. Addition of catalysts in the form of platinum nanoclusters and superacids to bacterial spores in a commercial pyrolyzer effected an increase in the amount of biomarkers produced at mild conditions over traditional pyrolysis methods. Electroformed nickel mesh, on the other hand, demonstrated low catalytic activity for the production of biomarkers, likely due to poor contact of the spores with the mesh. Biomarkers similar to those published in the literature were observed, including dipicolinic acid, picolinic acid, propionamide, acetamide, diketopiperazines, fatty acids, furfuryl alcohol, and DNA bases. A statistically designed factorial study was used to determine the importance of temperature, spore loading, and nanocluster loading on the production of three important biomarkers. The relative importance of these variables differs for each of the three important biomarkers, suggesting they are produced by different reaction mechanisms.

Catalytic Wet Air Oxidation Of Phenol In Concurrent Downflow And Upflow Packed-Bed Reactors Over Pillared Clay Catalyst, Jing Guo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

An Experimental Study is Presented for Comparing the Behavior of a Packed Bed Reactor in the Catalytic Liquid-Phase Oxidation of Aqueous Phenol with Two Modes of Operation, Downflow and Upflow. the Operating Parameters Investigated Included Temperature, Reactor Pressure, Gas Flowrate, Liquid Hourly Space Velocity and Feed Concentration. Because of the Completely Wetted Catalyst, the Upflow Reactor Generally Performs Better for High Pressures and Low Feed Concentrations When the Liquid Reactant Limitation Controls the Rate. the Interaction between the Reactor Hydrodynamics, Mass Transfer, and Reaction Kinetics is Discussed. for Both Operation Modes, Complete Phenol Removal and Significant Total Organic Carbon (TOC) …

A Sequential Approach To Modeling Catalytic Reactions In Packed-Bed Reactors, Jing Guo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

A Sequential Modeling Approach is Proposed to Simulate Catalytic Reactions in Packed-Bed Reactors. the Hydrogenation of Alpha-Methylstyrene and Wet Oxidation of Phenol Are Selected as Studied Cases. the Modeling Scheme Combines a Reactor Scale Axial Dispersion Model with a Pellet Scale Model. Without Involving Any Fitting Parameters, Such an Approach Accounts for the Non-Linear Reaction Kinetics Expression and Different Types of Pellet-Liquid Wetting Contact. to Validate the Developed Modeling Scheme and the Parallel Approach Reported in the Literature, the Experimental Observations for Hydrogenation of Alpha-Methylstyrene to Cumene Have Been Employed. the Predicted Results by Both Approaches Agree Reasonably with the …

Development Of A Novel Co Tolerant Proton Exchange Membrane Fuel Cell Anode, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang

Faculty Publications

Typically Pt is alloyed with metals such as Ru, Sn, or Mo to provide a more CO-tolerant, high-performance proton exchange membrane fuel cell (PEMFC) anode. In this work, a layer of carbon-supported Ru is placed between the Pt catalyst and the anode flow field to form a filter. When oxygen is added to the fuel stream, it was predicted that the slow H₂ kinetics of Ru in this filter would become an advantage compared to Pt and Pt:Ru alloy anodes, allowing a greater percentage of O₂ to oxidize adsorbed CO to CO₂. With an anode feed …

Using Sputter Deposition To Increase Co Tolerance In A Proton-Exchange Membrane Fuel Cell, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Narender Rana, Stephan Grunow, Timothy C. Stoner, Alain E. Kaloyeros

Faculty Publications

Placing a layer of Ru atop a Pt anode increases the carbon monoxide tolerance of proton-exchange membrane fuel cells when oxygen is added to the fuel stream. Sputter-deposited Ru filter anodes composed of a single Ru layer and three Ru layers separated by Nafion-carbon ink, respectively, were compared to Pt, Pt:Ru alloy, and an ink-based Ru filter anodes. The amount of Pt in each anode was 0.15 mg/cm² and the amount of Ru in each Ru-containing anode was 0.080 mg/cm². For an anode feed consisting of hydrogen, 200 ppm CO, and 2% O₂ (in the form …

Study Of Sn-Coated Graphite As Anode Material For Secondary Lithium-Ion Batteries, Basker Veeraraghavan, Anand Durairajan, Bala Haran, Branko N. Popov, Ronald Guidotti

Faculty Publications

Tin-graphite composites have been developed as an alternate anode material for Li-ion batteries using an autocatalytic deposition technique. The specific discharge capacity, coulombic efficiency, rate capability behavior, and cycle life of Sn-C composites has been studied using a variety of electrochemical methods. The amount of tin loading and the heating temperature have a significant effect on the composite performance. The synthesis conditions and Sn loading on graphite have been optimized to obtain the maximum reversible capacity for the composite electrode. Heating the composite converts it from amorphous to crystalline form. Apart from higher capacity, Sn-graphite composites possesses higher coulombic efficiency, …

A Novel Laboratory Course On Advanced Chemical Engineering Experiments, Jochen A. Lauterbach, S. White, X. Lui, G. M. Bodner, W. N. Delgass

Faculty Publications

The chemical engineering curriculum in the United States has trained generations of technical experts who have successfully optimized chemical processes and products once they entered the chemical industry. The U.S. chemical industry, however, has entered a critical stage in which it must be able to create new and differentiated value through technical innovations that arc essential for long-term survival. This innovation process will require new skills that go far beyond the traditional expertise for the optimization of tasks possessed by young chemical engineers. The innovators must be able to identify new opportunities, explore the boundaries of technology, evaluate critical issues, …

A Computer Simulation Of The Oxygen Reduction Reaction In Carbonate Melts, P. K. Adanuvor, Ralph E. White, A. J. Appleby

Faculty Publications

A computer simulation of the oxygen reduction reaction in various carbonate melts has been carried out under steady-state conditions on the basis of a proposed kinetic model which takes into consideration the autocatalytic reaction involving oxygen and other reducible oxygen species in the melt, and the neutralization of oxide ions by dissolved carbon dioxide. A simulation of the presence of (physically) dissolved oxygen, in the diffusion layer region of the melt, corresponding to the possible situation in porous electrodes, causes a significant enhancement in the polarization curves, particularly in the mass-transfer control region. On the other hand, high levels of …

Oxygen Reduction On Silver In 6.5 Molar Caustic Soda Solution, Prosper K. Adanuvor, Ralph E. White

Faculty Publications

No abstract provided.

Oxygen Reduction On Silver In 6.5m Caustic Soda Solution, Prosper K. Adanuvor, Ralph E. White

Faculty Publications

The cathodic reduction of oxygen in 6.5M membrane-grade caustic soda solution has been studied experimentally at a silver rotating disk electrode at 25°C. The results can be approximated by the parallel mechanism for oxygen reduction with catalytic decomposition of peroxide. Further analysis of this mechanism indicates that the sequential process with catalytic decomposition of peroxide predominates over the direct 4e^– process. Direct application of the sequential mechanism to the data indicates that the latter mechanism with catalytic decomposition of peroxide much more accurately reflects the experimental results. The relevant kinetic parameters are calculated on the basis of …

A Mathematical Model For The Initial Corrosion Rate Of A Porous Layer On A Rotating Disk Electrode, William E. Ryan, Ralph E. White, S. L. Kelly

Faculty Publications

A mathematical model is presented for the initial corrosion rate of a porous layer on a rotating disk electrode. The model is used to predict the corrosion potential and corrosion current density for a porous electrode made of pure iron in aerated caustic solutions. The dependence of these predictions on some of the properties of the porous layer is presented. It is shown that the corrosion rate depends significantly on the specific surface area of the porous electrode.

The Heterogeneous Catalytic Decomposition Of Isopropyl Alcohol Over 0.5% Platinum On 4-8 Mesh Charcoal Catalyst Support, Thomas Michael Kudenchak

Theses

The heterogeneous catalytic decomposition of isopropyl alcohol vapor over 0.5% platinum on (4-8 mesh) charcoal support catalyst was studied at bench-top in a fixed-bed tubular micro-reactor of about 1 cm ID, six inches long containing one or two grams of catalyst. Reactor feed and exit gas analysis was obtained by gas chromatography.

Experimental runs aimed at determining the Arrhenius parameters and the reaction order (assuming the applicability of a simple power law model) were performed with 1 and 2 grams of catalyst at various residence times ranging from 0.24 to 2.3 seconds and temperatures of 150°, 175°, 200°, 225°, and …