Catalysis and Reaction Engineering Commons^™

Effect Of Temperature On The Self-Humidifying Open-Cathode Proton Exchange Membrane Fuel Cell, Si-Chen Zhao, Ben Wang, Qiu-Hong Jia, Ming Han, Yu-Hong Xie

Journal of Electrochemistry

Based on the experiments about the output characteristics of a home-made temperature-controlled PEMFC system with atmospheric pressure and no external humidifying condition in different loading voltages and operating temperatures, the optimum operating temperature at different loading voltages can be obtained by tracking the output characteristics of PEMFC operating over a range of temperatures. By analyzing the fitted data the kinetic parameters are evaluated and the effect of different operating temperatures on the PEMFC performance is discussed from a view of electrode kinetics.

Development And Utilization Of A Pair Of Sol-Gel Entrapped Lipases For Biodiesel Production From High Free Fatty Acid Oils, Cory M. Schwartz

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Biodiesel, which consists of fatty acid alkyl esters, is one of the most widely adopted and successful renewable fuels. Traditional physiochemical biodiesel production methods require high cost refined feedstocks, and so alternative methods of catalysis and feedstocks have been explored. This research investigated the use of polysiloxane entrapped lipases to catalyze the production of biodiesel from low cost feedstocks.

In this work, lipase from Burkholderia cepacia (lipase PS) and lipase B from Candida antarctica (CalB) were separately entrapped using sol-gel chemistry. Optimal reaction conditions for the esterification of free fatty acids by immobilized CalB with methanol were determined. Immobilized CalB …

Influence Of Reduction Promoters On Stability Of Cobalt/Γ-Alumina Fischer-Tropsch Synthesis Catalysts, Gary Jacobs, Wenping Ma, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing surface Co⁰ site densities (e.g., in research catalysts), ultra-small crystallites (e.g., < 2–4.4 nm) formed are more susceptible to oxidation at high conversion relative to larger ones. The choice of promoter is important, as certain metals (e.g., Au) that promote cobalt oxide reduction can separate from cobalt during oxidation-reduction (regeneration) cycles. Finally, some elements have been identified to promote reduction but either poison the surface of Co⁰ (e.g., Cu), or produce excessive light gas selectivity (e.g., Cu and Pd, or Au at …

Phase Transitions Of Perfluorocarbon Nanoemulsion Induced With Ultrasound: A Mathematical Model, William G. Pitt, Ram N. Singh, Krystian X. Perez, Ghaleb A. Husseini, Daniel R. Jack

Faculty Publications

While ultrasound has been used in many medical and industrial applications, only recently has research been done on phase transformations induced by ultrasound. This paper presents a numerical model and the predicted results of the phase transformation of a spherical nanosized droplet of perfluorocarbon in water. Such a model has applications in acoustic droplet vaporization, the generation of gas bubbles for medical imaging, therapeutic delivery and other biomedical applications. The formation of a gas phase and the subsequent bubble dynamics were studied as a function of acoustic parameters, such as frequency and amplitude, and of the physical aspects of the …

Pulse Electrodeposition Of Pd-Ni Alloy Nanoparticles For Electrocatalytic Oxidation Of Formic Acid, Fang-Zu Yang, Jun-Pei Yue, Zhong-Qun Tian, Shao-Min Zhou

Journal of Electrochemistry

The Pd-Ni alloy nanoparticles with nickel atomic contents of 12.0%, 16.4% and 22.6% were successfully electrodeposited from a Pd-Ni alloy electrolyte by square wave pulse plating. The alloy nanoparticles were in the spherical shape with a diameter of 50 ~ 80 nm. As the growth potential of the alloy was negatively shifted, the nickel content of the alloy was increased, and the size of the nanoparticles was almost the same, whereas the number, the degree of crosslinking and the real active area of the nanoparticles were increased. As the nickel content of the alloy nanoparticles increased, the peak current for …

Synthesis And Electrochemical Properties Of Lico1-XMgXMno4 And Lico1-XAlXMno4 (X= 0, 0.02, 0.05, 0.1) As Positive Materials For Lithium-Ion Batteries, Mei-Ling You, Qing-Song Tong, Xiu-Hua Li, Min Lin, Xing-Kang Huang, Yong Yang

Journal of Electrochemistry

The Al-doped and Mg-doped LiCoMnO₄ materials were synthesized through solid-state reaction. The effects of doping amounts of Mg and Al on the initial capacities, discharge plateaus, and cycle performances were investigated. The morphologies and structures of the as-prepared materials were studied by scanning electron microscopy and powder X-ray diffraction. The results indicate that the as-prepared samples were composed of uniform, well-crystallized particles. The pristine LiCoMnO₄ possessed an initial capacity of 87.0 mAh·g^-1, while LiCo_0.98Mg_0.02MnO₄ and LiCo_0.98Al_0.02MnO₄ delivered 91.3 and 93.6 mAh·g^-1, respectively. The proper …

Fabrication And Impedance Performance Of Gradient Lani0.6Fe0.4O3-δ-Gd0.2Ce0.8O2 Composite Cathodes For Intermediate Temperature Solid Oxide Fuel Cell, Yang Li, Bo Huang, Meng Yuan, Zhi-Qiu Zhang, Zong-Yao Liu, Xu-Chen Tang, Xin-Jian Zhu

Journal of Electrochemistry

A LNF-GDC composite cathode with a gradual change in the composition between ScSZ electrolyte and LNF cathode was fabricated to reduce the cathode polarization resistance (R_p). The gradual change in composition between ScSZ electrolyte and LNF cathode shows the decreases in the charge transfer resistance (R_ct) and gas phase diffusion resistance (R_d). The results revealed that the Rp value, measuring 0.452 Ω·cm² at 750 °C, was the lowest for LNF-GDC composite cathodes with three layers and gradient changes in composition between ScSZ and LNF (Cathode C),, whereas the Rp value of 70%LNF-30%GDC composite …

Study On Carbon Supported Pd Catalysts Modified By Phosphomolybdic Acid For H2O2 Electrocatalytic Reduction, Li-Mei Sun, Cheng Zhang, Ying-Rong Bao, Hong-Xia Li

Journal of Electrochemistry

The Pd/C catalyst was prepared with the chemical reduction method, and phosphomolybdic acid (PMA) was modified on the Pd/C catalyst using the dipping method. The compositions and structures of the Pd/C and Pd/C modified by phosphomolybdic acid (PMA-Pd/C) catalysts were characterized with X-ray diffraction and Fourier Transform infrared spectroscopy analyses. The electrocatalytic activity and stability of the catalysts for the reduction of hydrogen peroxide (H₂O₂) were studied using cyclic voltammetry and chronoamperometry. The results showed that the phosphomolybdic acid was tightly fixed on the surface of Pd/C catalyst through the chemical interaction. The eletrocatalytic activity of …

Preparation Of Pd/Tio2/C Catalyst And Its Electrocatalytic Performance In Basic Solution For Ethanol Oxidation, Qiao-Xia Li, Yi-Chao Yang, Ming-Shuang Liu, Hong-Min Mao, Qun-Jie Xu

Journal of Electrochemistry

Nanoparticles TiO₂ were prepared by hydrothermal method using precursor tetrabutyl titanate. The Pd/TiO₂/C catalyst was synthesized by liquid phase reducing method supported on nano TiO₂ and Vulcan carbon XC-72. The Pd/TiO₂/C catalyst was characterized by XRD, TEM, cyclic voltammetry, and chronopotentiometry. XRD confirmed the face-centered cubic structure of Pd particles, and TEM indicated that Pd particles (size 3 ~ 4 nm) dispersed uniformly on TiO₂ and carbon XC-72. The results from cyclic voltammogram and chronopotentiogram showed the higher ethanol oxidation activity and stability of Pd/TiO₂/C catalyst (20% Pd) as compared with …

Electrochemical Oxidation Of Ammonium Nitrite In Absorption Solution Of Flue Gas, Yong-Hong Lu, Xiao-Bo Dong, Li-Sha Wang, Yan Liu, Chen-Jian Zhu, Hai-Bo Xu

Journal of Electrochemistry

In order to make full uses of ammonium nitrite in absorption solution from flue gas simultaneous desulfurization, denitrification and demercurization processes, here the electrochemical oxidation method was used to transform ammonium nitrite into ammonium nitrate. By using polarization curve, cyclic voltammogram and galvanostatic methods, suitable electrode materials were evaluated and chosen. The influence of electrolyte composition was discussed and the appropriate process parameters were obtained. Finally, the effect of electrochemical oxidation was confirmed by chemical analysis method. In 0.05 mol·L^-1 NaNO₂ + 0.05 mol·L^-1 (NH₄)₂SO₄ simulated absorption solution (5 L, pH = …

Enzyme Attached On Polymeric Micelles As A Nanoscale Reactor, Moo-Yeal Lee, Kyung-Jin Hong, Seung Pil Han, Toshio Kajiuchi

Chemical & Biomedical Engineering Faculty Publications

Similar to what lipase does, a surface-active enzyme was developed by attaching peroxidase on combshaped polymaleic anhydride-alt-1-tetradecene (PMA-TD) in a microemulsion system composed of n-butyl acetate and buffer solution, and its catalytic characteristics of polyphenol synthesis were investigated in an aqueous solution. The modified peroxidase with PMA-TD tended to form self-assembled aggregates like micelles in the aqueous solution and could be concentrated at solvent/water interfaces without unfolding of the enzyme. The efficiency of conversion of 2,4-dichlorophenol to phenolic oligomers was approximately 2-fold improved with the modified peroxidase compared to native peroxidase. The K _m and V _max values …

Mixed Surfactant Systems: Thermodynamics And Applications In Metal Oxide Imprinting, Suvid Joshi

Theses and Dissertations--Chemical and Materials Engineering

In this work we study mixtures of cationic surfactant (CTAB) and sugar based surfactant(s) (octyl beta-D-glucopyranoside (C8G1), dodecyl maltoside (C12G2) and octyl beta-D-xylopyranoside (C8X1)) to understand the non-ideal thermodynamic behavior of the mixtures of cationic and non-ionic surfactants in water and synthesis of imprinted materials. The thermodynamics of micellization, mixing and dilution of these systems are studied using Isothermal Titration Calorimetry (ITC) and the experimental data obtained are modeled with a pseudo-phase separation model with non-ideal mixing described by regular solution theory. It is shown that a model accounting for enthalpy of demicellization and enthalpy of dilution based on McMillan-Mayer …

Phenol Deoxygenation Over Hydrotreating Catalysts, Madelyn R B Ball

Honors Theses and Capstones

Phenol deoxygenation has been investigated as a model reaction for the deoxygenation of fatty acid methyl esters in biodiesel. Hydrodeoxygenated biodiesel is a drop-in fuel for petroleum diesel, and is a premium diesel with a high cetane number. As the first step in this research, two molybdenum catalysts were prepared, characterized and tested in a small-scale reactor. These catalysts were found to produce small amounts of benzene and cyclohexanol in the product stream, and confirmed the activity of the catalyst. A commercial cobalt molybdenum catalyst (Harshaw HT-400) was also tested and benzene, cyclohexanol, and cyclohexane were identified as products. Future …

Effects Of Sodium Hydroxide Pretreatment On Structural Components Of Biomass, Alicia A. Modenbach, Sue E. Nokes

Biosystems and Agricultural Engineering Faculty Publications

Pretreatment is a unit operation in the conversion of biomass to valuable products that utilizes various combinations of conditions, including chemicals, heat, pressure, and time, to reduce the recalcitrance of lignocellulose. Many such pretreatments have been developed over the years, as the operating conditions can be adapted so that lignocellulose is modified in ways unique to each pretreatment. By tailoring pretreatment conditions to achieve these modifications, the types of final products produced can be controlled. The purpose of this review is to provide a consolidated source of information for sodium hydroxide effects on lignocellulose. The structural characteristics of lignocellulose and …

Self-Healing Catalysts: Co3O4 Nanorods For Fischer-Tropsch Synthesis, Cun Wen, Darrius D. Dunbar, Xin Zhang, Jochen A. Lauterbach, Jason R. Hattrick-Simpers

Faculty Publications

We combine kinetic and spectroscopic data to demonstrate the concept of a self-healing catalyst, which effectively eliminates the need for catalyst regeneration. The observed self-healing is triggered by controlling the crystallographic orientation at the catalyst surface.

Development Of Nickel Oxide And Manganese Oxide Nanostructured Binary Modified Anodes For Methanol Electro-Oxidation, Ghada El-Nowihy

Chemical Engineering

No abstract provided.

A Modified Orthogonal Collocation Method For Reaction Diffusion Problems, Moustafa A. Soliman, Yousef S. Al-Zeghayer, Abdelhamid M. Ajbar

Chemical Engineering

A low-order collocation method is often useful in revealing the main features such as concentration and temperature profiles and the effectiveness factor for porous catalyst particles. Two modifications are introduced in this paper to make the method more efficient. The first modification is to add an extra collocation point at the center of the particle. It is shown that such extra point introduces a single variable non-linear equation to be solved after obtaining the standard collocation method solution. In the second modification, the polynomial solution obtained from the application of the orthogonal collocation method is transformed to a rational function …

Development Of Nickel Oxide And Manganese Oxide Nanostructured Binary Modified Anodes For Methanol Electro-Oxidation, Ghada El-Nowihy

Chemical Engineering

In this investigation, a nanoparticle-based binary catalyst composed of nickel oxide (nano-NiOx) and manganese oxide (nano-MnOx), both were assembled on a platinum substrate, was developed for the direct methanol electro-oxidation (MO) in an alkaline medium. The morphological investigation was performed using field-emission SEM and revealed the electrodeposition of MnOx in a nanorod structure and NiOx in round-shaped nanospheres. The electrocatalytic activity of the modified electrodes towards MO depended critically on the order of deposition of the two oxides. The optimum electrocatalytic activity was obtained at the MnOx/NiOx/Pt electrode (in which nano-NiOx was directly electrodeposited onto the Pt surface followed by …

One-Step Production Of Long-Chain Hydrocarbons From Waste-Biomass-Derived Chemicals Using Bi-Functional Heterogeneous Catalysts, Cun Wen, Elizabeth A. Barrow, Jason R. Hattrick-Simpers, Jochen A. Lauterbach

Faculty Publications

n this study, we demonstrate the production of long-chain hydrocarbons (C₈₊) from 2-methylfuran (2MF) and butanal in a single step reactive process by utilizing a bi-functional catalyst with both acid and metallic sites. Our approach utilizes a solid acid for the hydroalkylation function and as a support as well as a transition metal as hydrodeoxygenation catalyst. A series of solid acids was screened, among which MCM-41 demonstrated the best combination of activity and stability. Platinum nanoparticles were then incorporated into the MCM-41. The Pt/MCM-41 catalyst showed 96% yield for C₈₊ hydrocarbons and the catalytic performance was stable …

Quartz Crystal Microbalance Investigation Of Cellulosome Activity From Clostridium Thermocellum On Model Cellulose Films, Shanshan Zhou

Theses and Dissertations--Chemical and Materials Engineering

The cost of deconstructing cellulose into soluble sugars is a key impediment to the commercial production of lignocellulosic biofuels. The use of the quartz crystal microbalance (QCM) to investigate reaction variables critical to enzymatic cellulose hydrolysis is investigated here, extending previous studies of fungal cellulase activity for the first time to whole cell cellulases. Specifically, the activity of the cellulases of Clostridium thermocellum, which are in the form of cellulosomes, was investigated. To clearly differentiate the activity of free cellulosome and cell-bound cellulosome, the distribution of free cellulosome and cell-bound cellulosome in crude cell broth at different growth stages …