Chemical Engineering Commons^™

The Effects Of Inorganic Solids And Certain Gases On The Thermal Decomposition Of Catechol, Jerome Apilan Robles

LSU Doctoral Dissertations

In order to investigate the effects of calcium carbonate and iron oxide on the thermal decomposition of solid fuels, we have constructed an isothermal flow reactor to perform experiments on the model compound catechol (ortho-dihydroxybenzene), a phenol-type compound representative of coal, wood and biomass. Calcium carbonate and iron oxide are inorganic components of coal and wood, which have demonstrated catalytic properties in thermal reactions and are commercially used to enhance the conversion of solid fuels. In this study, the effects of the inorganic solids on pyrolysis and combustion are conducted through identification and quantification of the products formed after subjecting …

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 …

Low-Temperature Synthesis Of A Ptru/Nb0.1ti0.9o2 Electrocatalyst For Methanol Oxidation, Brenda L. García, Roderick Fuentes, John W. Weidner

Faculty Publications

Niobium was doped into anatase TiO2 support at 10 mol % (Nb0.1Ti0.9O2) using sol-gel chemistry. A PtRu/Nb0.1Ti0.9O2 catalyst was synthesized by LiBH4 reduction in tetrahydrofuran. The methanol electro-oxidation activity of the catalyst shows that this oxide support was electrically conductive. The current (A/gPt) was 6% higher on the PtRu/Nb0.1Ti0.9O2 catalyst compared to a commercial PtRu/C catalyst at 25°C. The electrochemically active surface area of the PtRu/C was 94% higher than PtRu/Nb0.1Ti0.9O2, thus the current per active site was 100% higher on PtRu/Nb0.1Ti0.9O2. A membrane electrode assembly with PtRu/Nb0.1Ti0.9O2 had 46% higher current (A/gPt) than an equivalent E-TEK membrane electrode assembly …

Gasification Kinetics Of Ultrafine Coal Char Oxidation In Flame Reactions, G John

Tanzania Journal of Engineering and Technology (TJET)

Pulverized coal combustion is exceedingly complex with a  vast number of variables. In order to avoid the complications associated with the burning of coal char, a controlled study has been made of the oxidation of fine graphite in laminar methane-air flame as a contribution to the understanding of the more complex phenomena of the gasification kinetics of the char. The burning of methane is equivalent to the burning of volatiles and graphite oxidation is similar to that of coal char. Aspects of this have been simulated in experimental and computational studies of 4pm diameter graphite particle burning in methane -air …

Supercritical-Carbon Dioxide-Assisted Cyclic Deposition Of Metal Oxide And Metal Thin Films, Dipak Barua, Theodosia Gougousi, Erin D. Young, Gregory N. Parsons

Chemical and Biochemical Engineering Faculty Research & Creative Works

Thin films of aluminum oxide and palladium were deposited on silicon at low temperatures (70-120 °C) by a cyclic adsorption/reaction processes using supercritical CO₂ solvent. Precursors included Al(hfac)₃, Al(acac)₃, and Pd(hfac)₂, and aqueous H₂O₂, tert-butyl peracetate, and H₂ were used as the oxidants or reductants. For the precursors studied, growth proceeds through a multilayer precursor adsorption in each deposition cycle, and film thickness increased linearly with the number of growth cycles.

Solid-Phase Oxygen Control System, Jian Ma, Mohamed Trabia, Yingtao Jiang, Samir Moujaes

Mechanical Engineering Faculty Research

Liquid lead and lead-bismuth eutectic (LBE) are good candidates for the nuclear coolant in accelerator-driven systems or advanced reactors [1]. Corrosion of containment and structural materials presents a critical challenge in the use of these materials as a nuclear coolant in accelerator-driven systems or advanced reactors [2]. One way to reduce the corrosion in liquid lead and LBE and in the whole circuit is to protect the structural materials with a stable oxide layer, and that layer can be sustained, provided a certain level of oxygen concentration in the LBE. This sets a lower limit on the oxygen concentration in …

Halonitromethane Treatment Using Advanced Oxidation Process: Rates, Mechanisms And Kinetic Modeling, Stuart Kirkham Cole

Civil & Environmental Engineering Theses & Dissertations

Halonitromethanes (HNMs) are low molecular weight halogenated disinfection-by-products (DBPs) found to be formed during ozonation, chlorination, or chloramination of waters containing natural bromide ion and nitrogenous organic matter. This work identifies the absolute rate constants for the oxidative hydroxyl radical (•OH) and reductive hydrated electron e^- _aq extinction of HNM compounds. Three forms of HNMs included in this study are the chlorinated, brominated, and mixed halogenated compounds. Electron pulse radiolysis and transient absorption spectroscopy were used to measure •OH and e^- _aq radical absolute reaction rate constants for a total of nine HNMs. To elucidate the decomposition reaction …

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 …

Studies On Capacity Fade Of Spinel-Based Li-Ion Batteries, Ramadass Premanand, Anand Durairajan, Bala Haran, Ralph E. White, Branko N. Popov

Faculty Publications

The performance of Cell-Batt^® Li-ion cells using nonstoichiometric spinel as the positive electrode material has been studied at different charging rates. The capacity of the cell was optimized based on varying the charging current and the end potential. Subsequent to this, the capacity fade of these batteries was studied at different charge currents. During cycling, cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. For all charge currents, the resistance of both the electrodes does not vary significantly with cycling. This result is in contrast with cells …

Electrochemical Filtering Of Co From Fuel-Cell Reformate, Balasubramanian Lakshmanan, Wayne Huang, John W. Weidner

Faculty Publications

A proton exchange membrane fuel cell was used as a flow reactor for continuous preferential oxidation of CO over H2 from 1.0% CO in H2 under pulse-potential control. By varying the pulse profile ~e.g., on-time, off-time, pulse potential! the CO and H2 oxidation currents were varied independently. The improvement in faradaic selectivity between CO and H2 oxidation results from the promotion of CO adsorption during the off ~i.e., open-circuit! portion of the pulse. Therefore, during the on portion CO oxidation was preferred while the surface was covered with CO.

Synthesis And Characterization Of Hydrous Ruthenium Oxide-Carbon Supercapacitors, Manikandan Ramani, Bala S. Haran, Ralph E. White, Branko N. Popov

Faculty Publications

It is shown that composite Ru oxide-carbon based supercapacitors possess superior energy and power densities as compared to bare carbon. An electroless deposition process was used to synthesize the ruthenium oxide-carbon composites. Ru is dispersed on the carbon matrix as small particles. The effect of electrochemical oxidation and temperature treatment on the material performance has been studied extensively. Increasing the oxidation temperature reduces the proton transport rate and also increases the degree of crystallinity of the deposits. This adversely affects the performance of the composite. Loading a small amount of Ru oxide (9 wt %) on carbon increases the capacitance …

Inherently Safer Analysis Of The Attainable Region Process For The Adiabatic Oxidation Of Sulfur Dioxide, Neil L. Book, Venkata U.B. Challagulla

Chemical and Biochemical Engineering Faculty Research & Creative Works

The attainable region (AR) method is used to obtain the optimal design and operating conditions for the adiabatic oxidation of sulfur dioxide to sulfur trioxide. The optimum process layout for this exothermic, catalytic, reversible reaction is a complex interconnection of reactors that achieves a conversion in excess of the equilibrium value for a single adiabatic reactor. The complex design obtained from the AR method is technically and economically superior to a single adiabatic reactor, but it is inferior from a safety perspective as a result of its complex interconnections and its high preheat temperature. The strategies of inherently safer design …

Improving The Accuracy Of Predicting Effectiveness Factors For Mth Order And Langmuir Rate Equations In Spherical Coordinates, Jianhui Hong, William C. Hecker, Thomas H. Fletcher

Faculty Publications

Char oxidation is often modeled using an mth order intrinsic reaction rate in conjunction with an effectiveness factor to account for intraparticle diffusion of gas species. This approach involves the use of a general modulus (M_T) and using the first-order curve of effectiveness factor vs M_T. This method was originally referred to as the general asymptotic solution. It has been suggested that a simple Langmuir rate equation is more suitable for modeling the effects of pressure on char reactivity. Therefore, several methods of developing general moduli for the Langmuir rate expression are shown. The general asymptotic …

Oxidation And Adsorption Of Deoxyribonucleic Acid At Highly Ordered Pyrolytic Graphite And Glass Carbon Electrode, Jian-Zhang Zhou, Ling-Ling Wu, Jin Luo, Zhong-Hua Lin

Journal of Electrochemistry

It is shown that calf thymus DNA (CT DNA) can be adsorbed at highly ordered pyrolytic graphite (HOPG) electrode and detected by differential pulse voltammetry (DPV) and electrochemical atomic force microscopy (ECAFM). It is found that controlled potential pre-polarization influences largely the adsorption of dsDNA while it has little influence on ssDNA. It is demonstrated that ECAFM is useful to exploit adsorption of DNA at HOPGE. The pattern of adsorption of DNA at HOPG electrode that fits best with the experimental data is proposed. The results aslo shows that UV/Vis reflection spectroscopy, which has not been used in studying electrochemical …

Oxidation Mechanism Of Hypophosphite, Dong-Bai Sun, Ying Jin, Hong-Ying Yu, De-Jun Yang

Journal of Electrochemistry

There exist two oxidation current peaks on the anodic polarization curve between -0.7 V and 0 V (SCE) in Na-hypophosphite solution. Peak Ⅰ (-0.55 V, SCE) , which represents the oxidation process from H₂PO₂^- to H₂PO₃^-, has been studied previously. Peak Ⅱ, which is located at the potential about -0.4 V (SCE), is investigated emphatically in this paper. The results show that, peak Ⅰ and Ⅱ are corresponding to two successive steps in oxidation process of H₂PO₂^-, i.e. peak Ⅱ corresponds to the oxidation process of …

Anodic Oxidation Of Ethylenediaminetetraacetic Acid On Platinum Electrode In Alkaline Medium, S. N. R. Pakalapati, Branko N. Popov, Ralph E. White

Faculty Publications

The anodic oxidation of ethylenediaminetetraacetic acid (EDTA) was studied in alkaline medium on a smooth platinum electrode. Bulk electrolysis indicated that stable organic intermediates (formaldehyde and glyoxal) are formed during the oxidation of EDTA and that complete oxidation to CO₂ can be achieved. The proposed pathway suggests that the acetate groups in EDTA are initially oxidized, generating formaldehyde and ethylenediamine. The rest potential of EDTA (0.066 to 0.164 V vs. Hg/HgO) was observed to be higher than for other organic species. In alkaline medium, very little EDTA oxidation was found to occur on bare platinum. Limiting-current behavior due to …

Linear Algebra Used To Determine Independent Half‐Cell Equations, D. H. Coleman, Ralph E. White

Faculty Publications

No abstract provided.

The Oxidation Of Hydrogen Absotbing Alloys And Its Inhibition, Suqin Wang, Baojia Xia, Geping Yin, Pengfei Shi

Journal of Electrochemistry

This paper introduces the method to judge: 1)the possibility of oxidation of themetal hydride electrode in an anode process by cyclic voltammetric curves, 2)the oxidation pattern ofmetal hydride electrode in oxygen atmosphere in various charged states, and 3)the inhibition ofoxidation of hydrogen absorbing alloys by certain surface treatment.

The Self-Discharge Of The Niooh/Ni(Oh)2 Electrode Constant Potential Study, Z. Mao, Ralph E. White

Faculty Publications

Hydrogen oxidation currents at a NiOOH/Ni(OH)₂ electrode were measured directly at constant potentials for various hydrogen pressures and states of charge. It was found that the hydrogen oxidation current is linearly proportional to the hydrogen pressure at all electrode potentials and that the logarithm of the anodic current is a linear function of electrode potential. It was also found that hydrogen oxidation on the nickel substrate material was strongly inhibited by the presence of nickel hydroxide on the substrate surface. By comparing the currents for hydrogen oxidation and oxygen evolution on the NiOOH/Ni(OH)₂ electrode and on a nickel …

Oxidation Of Toluene, Benzene And P-Xylene In A Photoreactor, Shiey-Shiun Horng

Theses

A new photoreactor was designed with stainless steel to oxidize refractory chemicals found on the EPA priority list. This new system was investigated by conducting experiments with three three model compounds, namely, toluene benzene and p-xylene. While toluene and benzene reactions are similar, they are faster with UV/ozone than UV/H₂O₂ and p-xylene reacts even faster with UV/ozone than UV/H₂O₂. The experimental data obtained were analyzed by GC and used to interpret the reaction kinetics from proposed models. The rate constants and mass transfer coefficients were found by using the Rosenbsrock Hillclimb optimization algorithm. …

The Effect Of The Tribromide Complex Reaction On The Oxidation/Reduction Current Of The Br2/Br– Electrode, P K. Adanuvor, Ralph E. White, S. E. Lorimer

Faculty Publications

The Br₂/Br^– electrode reaction with tribromide complex formation reaction in the solution, a chemical-electrochemical (C-E) type reaction, has been investigated in order to determine the effect of the chemical reaction on the electrode kinetics. It is shown that the chemical reaction has little effect on the electrode kinetics at very slow homogeneous reaction rates, but has a more drastic effect on the electrode kinetics at faster homogeneous reaction rates. Also, the kinetics at the electrode are affected by changes in the concentrations of the active species (Br₂, Br^–, and Br₃^–) …

An Analysis Of A Back Fed Porous Electorde For The Br2/Br- Redox Reaction, John W. Van Zee, Ralph E. White

Faculty Publications

No abstract provided.

An Analysis Of A Back Fed Porous Electrode For The Br2/Br Reaction, John Van Zee, Ralph E. White

Faculty Publications

An experimental analysis of the Br₂/Br^– redox reaction in a porous back fed ruthenium-coated titanium electrode is described. A mathematical model of the steady-state process is presented. Nonlinear regression of the model against the experimental data gives physically meaningful parameter estimates; these parameters and the model provide a design equation for the porous electrode current as a function of specific surface area, bulk Br₂ concentration, average total overpotential, and the Reynolds number. The design equation shows that the back fed electrode could reduce the loss of Br₂ across the separator and the ohmic loss in …

The Characterization Of The Oxygen Transfer Capabilities Of Fermentors, Joseph Stephen Adamca

Theses

A method of characterizing the oxygen mass transfer capabilities of fermentors was developed where volumetric oxygen mass transfer coefficients are obtained using a modified sulfite oxidation method in conjunction with on line digital data processing. Carboxymethylcellulose is used in the reaction media to simulate the viscosity of typical non-Newtonian fermentation broths. Using this method, instantaneous values of volumetric oxygen mass transfer coefficients can be obtained for various combinations of agitation and airflow rates in different fermentor configurations. This data is useful in the scale up or scale down of fermentors.

Data obtained using this method have revealed that for a …

Electrochemical Reduction Of Molybdenum(Vi) Compounds In Molten Lithium Chloride-Potassium Chloride Eutectic, Branko N. Popov, H. A. Laitinen

Faculty Publications

Molybdenum (VI) oxide reacts with molten LiCl-KCl eutectic at 450° to form MoO₂CI₂, which probably is present as an anion MoO₂Cl₄⁼, and pyromolybdate, Mo₂O₇⁼. Both of these species are electrochemically reduced to MoO₂, which can be reoxidized to MoO₂Cl₂ by current reversal. A second reduction step, observed whether MoO₃ or Mo₂O₇²⁻ is added to the melt, can be attributed to the reduction of MoO₄⁻⁻, formed as a secondary reaction product in the first …

An Oxidation Of Para-Nitrotoluene, Albert Edward Meisinger

Theses

The original purpose of this paper was to investigate the reaction kinetics of the air oxidation of para-nitro-toluene (PNT) to para-nitrobenzoic acid (PNBA). The reaction was to be carried out at atmospheric pressure and at temperatures between 100 and 175° C, and in the presence of an oxidation catalyst. However the main problem became one of trying to find a catalyst that would work at these conditions. The catalysts used were nickel acetate, cobaltous acetate, manganous acetate and manganese naphthenate. Hydrogen peroxide was tried as an accelerator for the reaction. None of these worked since no yield greater than 0.01% …

The Electrolytic Oxidation Of Para-Nitrotoluene, Mustafa Darwish Shamy

Theses

The factors affecting the electrolytic oxidation of p-nitrotoluene to p-nitrobenzoic acid have been studied, and optimum conditions determined for obtaining the best overall yield of 65.7 per cent. These Anode:lead sheetCathode:lead sheetAnolyte:250 cc of 50 per cent sulfuric acid
10 grams of p-nitrotoluene
5 grams of chromic trioxideCatholyte:250 cc of 50 per cent sulfuric acidVoltage:4.5 ± .5 voltsCurrent density:3.0 amperes per square decimeter.Temperatures65 ± 3°CReaction time:fifty per cent of the theoretical time required

It was observed that high potentials and prolonged reaction periods are detrimental to the yield.

A mechanism for the electrolytic oxidation process is suggested, based on experimental …