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Characterization of microenvironment polarity and solvent accessibility of polysilsesquioxane xerogels by the fluorescent probe technique

Description: Poly (1, 4 bis(triethoxysilyl)benzene) (PTESB), a representative of a new type of organic-inorganic hybrid polysilsesquioxane material, was characterized by fluorescence spectroscopy for both microenvironmental polarity and solvent accessibility. A dansyl fluorescent molecule was incorporated into the bulk as well as onto the surface of both PTESB and silica materials. Information about the microenvironment polarity and accessibility of PTESB to various organic solvents was determined and compared to that of silica gel. This study found that both the bulk and surface of PTESB are less polar than that of the silica material. The silica material is accessible to polar solvents and water, while YMB is accessible to polar solvents but not to water. The hydrophobicity of PTESB differentiates these new materials from silica gel.
Date: May 1, 1995
Creator: Shea, K.J.; Zhu, H.D. & Loy, D.A.
Partner: UNT Libraries Government Documents Department

HINDERED DIFFUSION OF ASPHALTENES AT ELEVATED TEMPERATURE AND PRESSURE

Description: During this time period work proceeded in two main areas, the performance and analysis of petroleum asphaltene diffusional uptake experiments at 325 C and the preparation and testing of some new carbon based catalysts. In the first area, we performed studies of the diffusion controlled uptake of petroleum asphaltenes into a porous carbon catalyst at 325 C. The experiments were performed under an inert He atmosphere using 1-methylnaphthalene as a solvent. These purpose of these experiments was to extend our previous data which was taken and reported in the prior semi-annual report. These previous experiments were performed only up to a temperature of 250 C. A comparison between the experimental data and model simulated data showed that the mathematical model satisfactorily fitted the adsorptive diffusion of the petroleum asphaltenes onto the porous carbon at 325 C. Comparing with previous results, the adsorption constant continued to decrease with an increase in temperature for the petroleum asphaltene/1-methylnaphthalene system. Also during this time period, some carbon catalyst supports were prepared in our laboratory and several sets of data were obtained in adsorption-diffusion uptake experiments using a petroleum asphaltene with toluene as solvent. These data are presented in this report, although, complete fitting of the data with the mathematical model has not yet been performed. These calculations will be performed during the next time period.
Date: September 29, 2000
Creator: Guin, James A.; Ramakrishnan, Ganesh; Asada, Keiji & Mosley, Brian
Partner: UNT Libraries Government Documents Department

HINDERED DIFFUSION OF ASPHALTENES AT ELEVATED TEMPERATURE AND PRESSURE

Description: The mathematical model which we have developed previously for diffusion controlled adsorption was extended to allow for the inclusion of the effects of extraparticle film mass transfer resistance as embodied in a finite Sherwood number. A Mathcad based program was used to simulate the experimental data using summation of a large number of terms in the infinite series solution. Parametric studies and accompanying plots revealed that the effects of film resistance on the uptake process were found to increase in significance as the adsorption capacity parameter in the model decreased. In addition, the two carbon catalyst supports prepared in our own laboratory were tested for their diffusional characteristics in uptake experiments using petroleum asphaltenes dissolved in toluene at three temperatures. The resulting experimental data were simulated with the mathematical model developed in the report.
Date: April 1, 2001
Creator: Guin, James A.; Ramakrishnan, Ganesh; Asada, Keiji & Mosley, Brian
Partner: UNT Libraries Government Documents Department

The crystallization of hectorite clays as monitored by small angle X-ray scattering and NMR

Description: The authors have probed the 48-hr crystallization of a magnesium silicate clay called hectorite. Small angle X-ray scattering (SAXS) at the Advanced Photon Source using aliquots ex situ has revealed that data is consistent with ex situ XRD, TGA, AFM, and IR data in that all these techniques see clay crystallite beginning to form in the first few hours of reaction. Tetraethylammonium (TEA) ions are used to aid crystallization and become incorporated as the exchange cations within the interlayers. {sup 13}C NMR shows that 80% of the final TEA loading is accomplished in the first 10 hrs. {sup 29}Si NMR displays a visible clay silicate peak after just 1 hr. In addition, the first in situ study of clay crystallization of any kind was performed by in situ SAXS. Results are consistent with the ex situ data as well as showing the sensitivity of SAXS to sol gel reactions occurring on the order of minutes.
Date: December 13, 1999
Creator: Carrado, K. A.; Xu, L.; Seifert, S.; Gregory, D.; Song, K. & Botto, R. E.
Partner: UNT Libraries Government Documents Department

Ion exchange properties of novel hydrous metal oxide materials

Description: Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.
Date: December 31, 1996
Creator: Gardner, T.J. & McLaughlin, L.I.
Partner: UNT Libraries Government Documents Department

Fundamental studies of supported bimetallic catalysts by NMR spectroscopy

Description: Various hydrogenation reactions on transition metals are important commercially whereas certain hydrogenolysis reactions are useful from fundamental point of view. Understanding the hydrogen mobility and kinetics of adsorption-desorption of hydrogen is important in understanding the mechanisms of such reactions involving hydrogen. The kinetics of hydrogen chemisorption was studied by means of selective excitation NMR on silica supported Pt, Rh and Pt-Rh catalysts. The activation energy of hydrogen desorption was found to be lower on silica supported Pt catalysts as compared to Rh and Pt-Rh catalysts. It was found that the rates of hydrogen adsorption and desorption on Pt-Rh catalyst were similar to those on Rh catalyst and much higher as compared to Pt catalyst. The Ru-Ag bimetallic system is much simpler to study than the Pt-Rh system and serves as a model system to characterize more complicated systems such as the K/Ru system. Ag was found to decrease the amounts of adsorbed hydrogen and the hydrogen-to-ruthenium stoichiometry. Ag reduced the populations of states with low and intermediate binding energies of hydrogen on silica supported Ru catalyst. The rates of hydrogen adsorption and desorption were also lower on silica supported Ru-Ag catalyst as compared to Ru catalyst. This report contains introductory information, the literature review, general conclusions, and four appendices. An additional four chapters and one appendix have been processed separately for inclusion on the data base.
Date: October 17, 1996
Creator: Savargaonkar, N.
Partner: UNT Libraries Government Documents Department

Technology development for iron fischer-tropsch catalysis

Description: The goal of the proposed work is the development of iron-based Fischer-Tropsch catalysts that combined high activity, selectivity and life with physical robustness for slurry phase reactors that will produce either low-alpha or high-alpha products. The catalyst that is developed will be suitable for testing at the Advanced Fuels Development Facility at LaPorte, Texas or similar sized plant. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the `standard-catalyst` developed by German workers for slurry phase synthesis. The proposed work will optimize the catalyst composition and pretreatment operation for this low- alpha catalyst. In parallel, work will be conducted to design a high- alpha iron catalyst that is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studied at the laboratory scale. Catalyst performance will be determined for 5 catalysts synthesized in this program for activity, selectivity and aging characteristics.
Date: May 14, 1997
Creator: Davis, B.H.
Partner: UNT Libraries Government Documents Department

Characterization of nanostructured zirconia prepared by hydrolysis and reverse micelle synthesis by small-angle neutron and X-ray scattering

Description: Low temperature techniques such as hydrolysis and reverse micelle syntheses provide the opportunity to determine the relationship between the structural properties and preparation conditions of zirconia powders as well as to tailor their physicochemical properties. The authors have performed small-angle neutron and synchrotron X-ray scattering (SANS and SAXS) experiments to study the nucleation and organization of zirconia nanoparticles via different preparation routes. First, the formation of reverse micelles in individual and mixed solutions of (ZrOCl{sub 2}+D{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3}, and (NH{sub 4}OH+H{sub 2}O)/AOT/C{sub 6}D{sub 5}CD{sub 3} systems at water/AOT molar ratio of 20 was characterized. Second, the aggregation of zirconia gels obtained from the reaction of the reverse micelle solutions after heat treatments was studied. Third, the nanostructure of zirconia powders prepared by the reverse micelle method is compared with the corresponding powders prepared by hydrolysis after different heat treatments.
Date: December 7, 1999
Creator: Thiyagarajan, P.; Li, X.; Littrell, K.; Seifert, S.; Csencsits, R. & Loong, C.
Partner: UNT Libraries Government Documents Department

Task 5.4 -- Stable and supercritical chars. Semi-annual report, January 1--June 30, 1995

Description: The use of chars and carbons as absorbents and catalyst supports could be expanded if their stability to reactive gases were improved. The purpose of this task is to develop methods for applying surface coatings of boron carbide, silicon carbide, and titanium carbide on the char. Formation of these composites will increase stability and improve structural strength and, consequently, resistance to abrasion. The first objective of this task is to develop methods for coating low-rank coal (LRC) chars and carbons by chemical vapor deposition (CVD) to produce high surface area composites that are inert to reactive atmospheres. The proposed coating layers will be formed from elements known to form extremely hard and stable carbide materials. The second objective is to determine the feasibility of using supercritical extraction to prepare an activated carbon with a very high surface area. During this report period supercritical solvent extraction was investigated as a means of producing very large microporous structures in chars. Wyodak subbituminous coal, Gascoyne lignite, and Velva lignite were used for the supercritical extractions.
Date: December 31, 1995
Creator: Olson, E.S. & Sharma, R.K.
Partner: UNT Libraries Government Documents Department

Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports

Description: The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-{alpha}-acetamidocinnamate (MAC), has the illustrated structure as established by {sup 31}P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H]{sub 4}, [Rh(COD){sub 2}]{sup +}BF{sub 4}{sup -}, [Rh(COD)Cl]{sub 2}, and RhCl{sub 3} {center_dot} 3H{sub 2}O, adsorbed on SiO{sub 2} are optimally activated for toluene hydrogenation by pretreatment with H{sub 2} at 200 C. The same complexes on Pd-SiO{sub 2} are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH{sub 2}){sub 3}s-]Re(O)(Me)(PPh{sub 3}) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.
Date: May 31, 2003
Creator: Stanger, Keith James
Partner: UNT Libraries Government Documents Department

PREPARATION AND CHARACTERIZATION OF NANOSTRUCTURED GRANULAR SUPPORT PARTICLES AND CATALYTIC MATERIALS

Description: We have set up successfully two experimental systems during the past time of the project. The first system is sol-gel chemical method for preparing {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, Cr{sub 2}O{sub 3} granular support particles. The second system is the laser-induced solution deposition (LISD) technique for nanoparticle catalysts containing Fe/Cu, and Co/Cu on the granular support. We have successfully deposited {gamma}-Al{sub 2}O{sub 3}, SiO{sub 2}, Cr{sub 2}O{sub 3} granular support particles by sol-gel method and Co and CoO nanoparticles by LISD novel fabrication technique. The characterization methods we have used include scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM) and X-Ray diffraction (XRD). The research toward to the proposed direction is in good progress. We have given three presentations in national and local materials meetings and have submitted another two papers in another two key national meetings in nanotechnology and American Physical Annual March Meeting 2002. A couple of papers are in preparation.
Date: January 15, 2002
Creator: Zhong, Zhenchen
Partner: UNT Libraries Government Documents Department

Mechanism of hydrodenitrogenation preparation of supported Ru catalysts. Twelfth quarter report, July 1--August 31, 1992

Description: A series of Ru oxide catalysts has been prepared and partially characterized. Starting from Ru(NO)(NO{sub 3}){sub 3} to avoid residual Cl in the catalysts, Ru{sup +3} oxides have been prepared in loadings of 1,4 and 8 wt%, over silica, gamma-alumina and silica-aluminas of controlled acidity. The highly dispersed oxides are produced in order to study the controllability of the various types of catalytic functionalities present on HDN catalysts.
Date: December 31, 1992
Creator: Miranda, R.
Partner: UNT Libraries Government Documents Department

Engineered Nanostructured MEA Technology for Low Temperature Fuel Cells

Description: The objective of this project is to develop a novel catalyst support technology based on unique engineered nanostructures for low temperature fuel cells which: (1) Achieves high catalyst activity and performance; (2) Improves catalyst durability over current technologies; and (3) Reduces catalyst cost. This project is directed at the development of durable catalysts supported by novel support that improves the catalyst utilization and hence reduce the catalyst loading. This project will develop a solid fundamental knowledge base necessary for the synthetic effort while at the same time demonstrating the catalyst advantages in Direct Methanol Fuel Cells (DMFCs).
Date: July 16, 2009
Creator: Zhu, Yimin
Partner: UNT Libraries Government Documents Department

Clean gasoline reforming with superacid catalysts. Quarterly progress report, April--June 1992

Description: It has been observed for a number of the Zr catalysts that the maximum MCH conversion (ca. 20 wt.%) can be obtained in 15 min. using a reaction temperature of 150{degrees}C and 1 atm. of H{sub 2}, and no further reaction occurs during 120 minutes. Typical results for these catalysts as well as catalyst which show lower activities using the 15 min. residence time are shown in Figure 2. Both catalyst formulations, a Pt/ZrO{sub 2}/SO{sub 4} and a Fe/Mn/ZrO{sub 2}/SO{sub 4} show this behavior. The 15 minute conversion and the 2 hour conversion are not due to thermodynamic limitations. A series of experiments were completed using the Pt/ZrO{sub 2}/SO{sub 4} catalyst to obtain data to explain the maximum conversions obtained. In the first set of experiments a conversion versus residence time curve (Figure 3) was generated. The data shown in Figure 3 indicated a conversion curve with reaction time that is typical of the catalysts tested. In the next set of experiments, the amount of reactor volume which was occupied by the catalyst and feedstock was varied to determine if the reaction taking place in the liquid or gas phase was limiting the conversion of MCH. The MCH/catalyst ratio was held constant at 2:1. The results of these experiments are shown in Figure 4. The data clearly indicates that the conversion remains fairly constant until the reactor it essentially filled with liquid. It does not appear that the limited maximum conversion observed is due to the reaction taking place in either the gas or liquid phase.
Date: August 4, 1992
Creator: Davis, B. H.
Partner: UNT Libraries Government Documents Department

HINDERED DIFFUSION OF ASPHALTENES AT ELEVATED TEMPERATURE AND PRESSURE

Description: During this past six months we continued our ongoing studies of the diffusion controlled uptake of coal and petroleum asphaltenes into a porous carbon catalyst. Toluene was used as the solvent for experiments at 20 C and 75 C while 1-methylnaphthalene was the solvent for the higher temperature experiments at 100 C, 150 C and 250 C. All runs were made at a pressure of 250 psi (inert He gas). Experiments were performed at 20 C and 75 C, for the petroleum asphaltene/toluene system. For the coal asphaltene/toluene system, experiments were performed at 75 C. Experiments were performed at 100 C, 150 C and 250 C for the coal asphaltene/1-methylnaphthalene system. A comparison between the experimental data and model simulated data showed that the mathematical model satisfactorily fitted the adsorptive diffusion of both the coal and petroleum asphaltenes onto a porous activated carbon. The adsorption constant decreases with an increase in temperature for both, the coal asphaltene/1-methylnaphthalene system as well as the petroleum asphaltene/toluene system. It was found that the adsorption constant for the coal asphaltene/toluene system at 75 C was much higher than that of the petroleum asphaltene/toluene system at the same temperature providing evidence of the greater affinity of the coal asphaltenes for the carbon surface. This could be due to the presence of more functional heteroatomic groups in the coal asphaltenes compared to their petroleum counterparts. Also during this time period, a new carbon catalyst support was prepared in our laboratory which will be used in adsorption experiments during the next phase of work.
Date: April 7, 2000
Creator: Guin, James A.; Ramakrishnan, Ganesh & Asada, Keiji
Partner: UNT Libraries Government Documents Department

Catalytic reduction of SO{sub 2} with methane over molybdenum catalyst. Quarterly report, 1 December 1994--28 February 1995

Description: One of the primary concerns in coal utilization is the emission of sulfur compounds, especially SO{sub 2}. This project deals with catalytic reduction of SO{sub 2} with methane using molybdenum sulfide catalyst supported on different activated carbons: Darco TRS, Norit ROZ-3, and an activated carbon prepared from Illinois coal IBC-110. The work conducted during this quarter has concentrated on continuation of the synthesis of activated carbon derived from Illinois coal IBC-110, modification and improvement of the apparatus for the catalyst testing, ESCA (XPS) analysis of the catalyst (10% MoS{sub 2} on Darco TRS activated carbon), and experiments in the temperature range of 450{degree}C--600{degree}C for the S0{sub 2}:CH{sub 4} ratio equal 1:1. XPS study confirmed that Mo is present in the form of Mo+4 and S in the form of S-2. The catalytic experiments of SO{sub 2} reduction with CH{sub 4} showed that for both Darco TRS and ROZ-3 supports, S0{sub 2} conversion increases with the temperature. Also, the catalyst having 20% loading of MoS{sub 2} on Darco TRS support shows the highest S0{sub 2} conversion over 10% or 15% loadings on Darco TRS. In contrast, for the ROZ-3 support, the catalyst having a 15% loading shows the highest activity. Additionally, it was observed that conversions of S0{sub 2} at 600{degree}C for both supports are comparable to each other when catalysts with 20% loadings are used; at lower temperatures, the activities are quite different with the conversions being higher for Darco TRS support.
Date: December 31, 1995
Creator: Wiltowski, T.
Partner: UNT Libraries Government Documents Department

Novel catalysts for upgrading coal-derived liquids. Quarterly technical progress report, December 1, 1994--February 28, 1995

Description: We evaluated the methylcarbazole hydrodenitrogenation (HDN), dibenzothiophene hydrodesulfurization (HDS) and dibenzofuran hydrodeoxygenation (HDO) activities of the supported nitride that was most active for the hydrotreatment of lower molecular weight heteroatom compounds. This catalyst was prepared in our laboratory and compared with commercial sulfide hydrotreatment catalysts.
Date: December 31, 1994
Creator: Thompson, L.T.; Savage, P.E. & Briggs, D.E.
Partner: UNT Libraries Government Documents Department

Support chemistry, surface area, and preparation effects on sulfided NiMo catalyst activity

Description: Hydrous Metal Oxides (HMOs) are chemically synthesized materials which contain a homogeneous distribution of ion exchangeable alkali cations that provide charge compensation to the metal-oxygen framework. In terms of the major types of inorganic ion exchangers defined by Clearfield, these amorphous HMO materials are similar to both hydrous oxides and layered oxide ion exchangers (e.g., alkali metal titanates). For catalyst applications, the HMO material serves as an ion exchangeable support which facilitates the uniform incorporation of catalyst precursor species. Following catalyst precursor incorporation, an activation step is required to convert the catalyst precursor to the desired active phase. Considerable process development activities at Sandia National Laboratories related to HMO materials have resulted in bulk hydrous titanium oxide (HTO)- and silica-doped hydrous titanium oxide (HTO:Si)-supported NiMo catalysts that are more active in model reactions which simulate direct coal liquefaction (e.g., pyrene hydrogenation) than commercial {gamma}-Al{sub 2}O{sub 3}-supported NiMo catalysts. However, a fundamental explanation does not exist for the enhanced activity of these novel catalyst materials; possible reasons include fundamental differences in support chemistry relative to commercial oxides, high surface area, or catalyst preparation effects (ion exchange vs. incipient wetness impregnation techniques). The goals of this paper are to identify the key factors which control sulfided NiMo catalyst activity, including those characteristics of HTO- and HTO:Si-supported NiMo catalysts which uniquely set them apart from conventional oxide supports.
Date: June 1, 1996
Creator: Gardner, T.J.; McLaughlin, L.I. & Sandoval, R.S.
Partner: UNT Libraries Government Documents Department

Development of a stable cobalt-ruthenium Fisher-Tropsch catalyst. Final report

Description: The reverse micelle catalyst preparation method has been used to prepare catalysts on four supports: magnesium oxide, carbon, alumina- titania and steamed Y zeolite. These catalysts were not as active as a reference catalyst prepared during previous contracts to Union Carbide Corp. This catalyst was supported on steamed Y zerolite support and was impregnated by a pore-filling method using a nonaqueous solvent. Additional catalysts were prepared via pore- filling impregnation of steamed Y zeolites. These catalysts had levels of cobalt two to three and a half times as high as the original Union Carbide catalyst. On a catalyst volume basis they were much more active than the previous catalyst; on an atom by atom basis the cobalt was about of the same activity, i.e., the high cobalt catalysts` cobalt atoms were not extensively covered over and deactivated by other cobalt atoms. The new, high activity, Y zerolite catalysts were not as stable as the earlier Union Carbide catalyst. However, stability enhancement of these catalysts should be possible, for instance, through adjustment of the quantity and/or type of trace metals present. A primary objective of this work was determination whether small amounts of ruthenium could enhance the activity of the cobalt F-T catalyst. The reverse micelle catalysts were not activated by ruthenium, indeed scanning transmission electronic microscopy (STEM) analysis provided some evidence that ruthenium was not present in the cobalt crystallites. Ruthenium did not seem to activate the high cobalt Y zeolite catalyst either, but additional experiments with Y zeolite-supported catalysts are required. Should ruthenium prove not to be an effective promoter under the simple catalyst activation procedure used in this work, more complex activation procedures have been reported which are claimed to enhance the cobalt/ruthenium interaction and result in activity promotion by ruthenium.
Date: February 1, 1995
Creator: Frame, R.R. & Gala, H.B.
Partner: UNT Libraries Government Documents Department

Catalytic reduction of SO{sub 2} with methane over molybdenum catalyst. Quarterly technical report, September 1, 1994--November 30, 1994

Description: One of the primary concerns in coal utilization is the emission of sulfur compounds, especially SO{sub 2}. This project deals with catalytic reduction of SO{sub 2} with methane using molybdenum sulfide catalyst supported on different activated carbons: Darco TRS, Norit ROZ-3, and an activated carbon prepared from Illinois coal IBC-110. The work conducted during this quarter has concentrated on catalyst preparation and characterization along with synthesis of activated carbon from IBC-110 coal, as well as, construction of the apparatus for catalytic tests of SO{sub 2} reduction with methane. It was found that Darco TRS supported catalysts have larger surface area than the pure activated carbon, whereas the impregnation of Norit ROZ-3 did not significantly change the BET surface area. Also, the synthesis of activated carbon support from IBC-110 is in progress.
Date: March 1995
Creator: Wiltowski, T.
Partner: UNT Libraries Government Documents Department

Electrical communication between glucose oxidase and different ferrocenylalkanethiol chain lengths

Description: We describe the factors affecting the electron transfer process between the different components of a self-assembled mixed monolayer. The system is comprised of mixed monolayers containing aminoalkanethiols (AMATs) and ferrocenylakanethiols (FATs) of variable chain lengths. We study the effects of different ratio of the two mixed monolayer components on the permeability of the monolayer toward a Ru(NH{sub 3}{sub 6}Cl{sub 3} redox probe. In order to study the electrical communication between the enzyme and the mediator molecules, the enzyme glucose oxidase (GOx) was attached to the AMAT sites to create a biosensor device. The relative efficiency of a biosensor of each chain-length combination of FAT and AMAT was examined. In light of this comparison, we consider the critical factors for efficient electron transfer between the ferrocene mediator and the GOx redox active site immobilized as part of the surface-confined system. We find that the biosensor response is greatest when the enzyme and the FATs are attached to the surface with different alkane chain lengths. We also find strong evidence for the existence of domains of FAT and AMAT in the mixed monolayer system.
Date: December 31, 1995
Creator: Rubin, S.; Bar, G.; Cutts, R.W.; Zawodzinski, T.A. Jr.; Chow, J.T. & Ferraris, J.P.
Partner: UNT Libraries Government Documents Department

The economical production of alcohol fuels from coal-derived synthesis gas. Quarterly report, October 1, 1996--December 31, 1996

Description: The objective of Task 1 is to prepare and evaluate catalysts and to develop efficient reactor systems for the selective conversion of hydrogen-lean synthesis gas to alcohol fuel extender and octane enhancers. Task 1 is subdivided into three separate subtasks: laboratory and equipment setup; catalysis research; and reaction engineering and modeling. Research at West Virginia University (WVU) is focused on molybdenum-based catalysts for higher alcohol synthesis. Parallel research carried out at Union Carbide Corporation (UCC) is focused on transition-metal-oxide catalysts. During this time period, at WVU, we tried several methods to eliminate problems related to condensation of heavier products when reduced Mo-Ni-K/C materials were used as catalysts. We then resumed our kinetic study on the reduced Mo-Ni-K/C materials were used as catalysts. We then resumed our kinetic study on the reduced Mo-Ni-K/C catalysts. We have also obtained same preliminary results in our attempts to analyze quantitatively the temperature-programmed reduction spectra for C- supported Mo-based catalysts. We have completed the kinetic study for the sulfided Co-K-MoS{sub 2}/C catalyst. We have compared the results of methanol synthesis using the membrane reactor with those using a simple plug-flow reactor. At UCC, the complete characterization of selected catalysts has been completed. The results suggest that catalyst pretreatment under different reducing conditions yield different surface compositions and thus different catalytic reactivities.
Date: January 1, 1997
Partner: UNT Libraries Government Documents Department

Slurry phase iron catalysts for indirect coal liquefaction. Semi- annual technical report, July 4, 1996--January 5, 1997

Description: This report describes research conducted to support the DOE program in indirect coal liquefaction. Specifically, we have studied the attrition behavior of iron Fischer-Tropsch catalysts, their interaction with the silica binder and the evolution of iron phases in a synthesis gas conversion process. The results provide significant insight into factors that should be considered in the design of catalysts for converting coal based syn-gas into liquid fuels.
Date: February 1, 1997
Creator: Datye, A.K.
Partner: UNT Libraries Government Documents Department