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Catalytic conversion of light alkanes -- research and proof-of-concept stages

Description: Objective is to find new catalysts for direct reaction of methane, ethane, propane, butanes with O{sub 2} to form alcohols, and to develop practical processes for direct oxidative conversion of natural gas and its C{sub 1}-C{sub 4} components to produce alcohol-rich liquid oxygenates for use as alternative transportation fuels/environmentally superior reformulated gasolines. The proposed mechanism for oxidation activity of cytochrome P-450 and methane monoxygenase suggested that a catalyst able to reductively bind oxygen, not between Fe(III) center and a proton, but between two Fe(III) centers, might give the desired dioxygenase activity for alkane hydroxylation. Selective oxidation of light alkanes could be done by oxidation-active metal (Fe) centers in electron-deficient prophyrin-like macrocycles, polyoxoanions, and zeolites. In the isobutane conversion to tert-butanol proof-of-concept, it was found that nitro groups on the periphery of Fe porphyrin complexes give the greatest increase in Fe(III)/(II) reduction potential. 8 figs, 6 tabs, 40 refs.
Date: December 31, 1993
Creator: Lyons, J. E. & Hancock, A. W. II
Partner: UNT Libraries Government Documents Department

Redox Reactions of Metalloporphyrins and their Role in Catalyzed Reduction of Carbon Dioxide

Description: Pulse radiolysis and laser photolysis are used to study redox processes of metalloporphyrins and related complexes in order to evaluate these light absorbing molecules as sensitizers and intermediates in solar energy conversion schemes. The main thrust of the current studies is to investigate the role of reduced metalloporphyrins as intermediates in the catalyzed reduction of carbon dioxide. Studies involve cobalt and iron porphyrins, phthalocyanines, corroles, and corrins as homogeneous catalysts for reduction of carbon dioxide in solution. The main aim is to understand the mechanisms of these photochemical schemes in order to facilitate their potential utilization.
Date: September 1, 2002
Creator: Neta, P.
Partner: UNT Libraries Government Documents Department

Abiotic reduction of aquifer materials by dithionite: A promising in-situ remediation technology

Description: Laboratory batch and column experiments were conducted with Hanford sediments to develop the capability to predict (1) the longevity of dithionite in these systems, (2) its efficiency as a reductant of structural iron, and (3) the longevity and reactivity of the reduced iron with soluble inorganic and organic species. After an initial induction period, the loss of dithionite by disproportionation and oxidation could be described by pseudo-first-order (PFO) kinetics. Other than the initial reaction with ferric iron, the primary factor promoting loss of dithionite in this system was disproportion nation via heterogeneous catalysis at mineral surfaces. The efficiency of the reduction of structural iron was nearly 100% for the first fourth of the ferric iron, but declined exponentially with higher degrees of reduction so that 75% of the ferric iron could be reduced. This decrease in reduction efficiency probably was related to differences in the accessibility of ferric iron in the mineral particles, with iron in clay-sized particles being the most accessible and that in silt- and sand-sized particles less accessible. Flow-through column studies showed that a reduced-sediment barrier created in this manner could maintain a reducing environment.
Date: November 1, 1994
Creator: Amonette, J.E.; Szecsody, J.E.; Schaef, H.T.; Gorby, Y.A.; Fruchter, J.S. & Templeton, J.C.
Partner: UNT Libraries Government Documents Department

Binuclear Non-heme Iron Catalysts

Description: This project involved the investigation of the ability of non-heme iron metalloenzyme reactivity model complexes to catalyze the oxidation of alkane and arene molecules. The objectives were to synthesize a series of non-heme mononuclear and dinuclear iron complexes, characterize their electronic structure and reactivity properties, characterize intermediates formed during oxygen atom transfer chemistry, and elucidate the mechanisms and specificity of the reactions.
Date: May 27, 2004
Creator: Caradonna, J. P.
Partner: UNT Libraries Government Documents Department

The synthesis and characterization of new iron coordination complexes utilizing an asymmetric coordinating chelate ligand

Description: A binuclear, unsymmetric coordinating ligand that is an effective metal chelator has been designed and synthesized. The new ligand has been shown to react readily with iron(II)/(III) forming a variety of coordination complexes. The binuclear complexes are of significant interest since they represent proof-of-principle for the development of coordinatively asymmetric, binuclear metal chelate compounds. Although this structural type of chelator now appears to be common in biological systems, it has not been previously described for inorganic coordination chemistry. The isolation of oxidation products will be helpful in establishing reaction mechanism(s) of these complexes with molecular oxygen. It is expected that this ligand and derivatives of it will play an important role in the development of bioinorganic complexes that aim to mimic enzyme active sites that function by substrate interaction at only one metal site of a multimetal active site.
Date: July 1, 1995
Creator: Watkins, B.E. & Satcher, J.H.
Partner: UNT Libraries Government Documents Department

Intramolecular energy- and electron-transfer reactions in polymetallic complexes. Annual report

Description: The complexes (tpy)Ru(II)(tpp)Co(III)(PPhEt{sub 2})H{sub 2}{sup 3+}, (NC){sub 3}Fe(II)(tpp)Co(III)(PPhEt{sub 2})H{sub 2} and (NC){sub 3}Fe(II)(tpp)Co(III)(PPh{sub 3})H{sub 2} (where tpp = 2,3,5,6-tetrakis(2{prime}-pyridyl)pyrazine), were prepared and their photochemistry studied. Reasons for the low quantum yields for H{sub 2} production are discussed briefly. A series of FeRuRh complexes is being prepared. Plans for the coming year on intramolecular energy transfer and charge separation are discussed.
Date: December 1, 1991
Creator: Peterson, J.D.
Partner: UNT Libraries Government Documents Department

Twenty-five years of artificial photosynthesis research at Ernest Orlando Lawrence Berkeley National Laboratory

Description: This report summarizes the research done on artificial photosynthesis by the Calvin Group between 1970 and 1995 when the program was terminated. It contains a compilation of the personnel involved as well as a bibliography of publications supported by the project.
Date: February 1, 1996
Creator: Otvos, J.W. & Calvin, M.
Partner: UNT Libraries Government Documents Department

Actinide complexation kinetics: rate and mechanism of dioxoneptunium (V) reaction with chlorophosphonazo III

Description: Rates of complex formation and dissociation in NpO{sub 2}{sup +}- Chlorophosphonazo III (2,7-bis(4-chloro-2-phosphonobenzeneazo)-1,8- dihydroxynapthalene-3,6-disulfonic acid)(CLIII) were investigated by stopped-flow spectrophotometry. Also, limited studies were made of the rates of reaction of La{sup 3+}, Eu{sup 3+}, Dy{sup 3+}, and Fe{sup 3+} with CLIII. Rate determining step in each system is an intramolecular process, the NpO{sub 2}{sup +}-CLIII reaction proceeding by a first order approach to equilibrium in the acid range from 0.1 to 1.0 M. Complex formation occurs independent of acidity, while both acid dependent and independent dissociation pathways are observed. Activation parameters for the complex formation reaction are {Delta}H=46.2{+-}0.3 kJ/m and {Delta}S=7{+-} J/mK (I=1.0 M); these for the acid dependent and independent dissociation pathways are {Delta}H=38.8{+-}0.6 kJ/m, {Delta}S=-96{+-}18 J/mK, {Delta}H=70.0{+-} kJ/m, and {Delta}S=17{+-}1 J/mK, respectively. An isokinetic relationship is observed between the activation parameters for CLIII complex formation with NpO{sub 2}{sup +}, UO{sub 2}{sup 2+}, Th{sup 4+}, and Zr{sup 4+}. Rates of CLIII complex formation reactions for Fe{sup 3+}, Zr{sup 4+}, NpO{sub 2}{sup +}, UO{sub 2}{sup 2+}, Th{sup 4+}, La{sup 3+}, Eu{sup 3+}, and Dy{sup 3+} correlate with cation radius rather than charge/radius ratio.
Date: December 1, 1996
Creator: Fugate, G.; Feil-Jenkins, J.F.; Sullivan, J.C. & Nash, K.L.
Partner: UNT Libraries Government Documents Department

Upgrading of heavy oil from the San Joaquin Valley of California by aqueous pyrolysis

Description: Midway Sunset crude oil and well-head oil were treated at elevated temperatures in a closed system with the presence of water. Mild to moderate upgrading, as measured by increase in API gravity, was observed at 400{degrees}C or above. Reduced pressure operation exhibited upgrading activity comparable to upgrading under normal aqueous pyrolysis conditions. Reduced pressure operation was obtained by the use of specific blending methods, a surfactant, and the proper amount of water. The use of additives provided additional upgrading. The best of the minimum set tested was Co(II) 2-ethylhexanoate. Fe(III) 2-ethylhexanoate also showed some activity under certain conditions.
Date: October 1, 1995
Creator: Reynolds, J.G.; Murray, A.M.; Nuxoll, E.V. & Fox, G.A.
Partner: UNT Libraries Government Documents Department

Biomimetic methane oxidation. Final report, October 1, 1989--June 1, 1995

Description: Transportation fuels are a critical energy commodity and they impact nearly every sector of this country. The need for transportation fuels is projected well into the next century. Consequently, there is a strong emphasis on the economical conversion of other domestic fossil energy resources to liquid hydrocarbons that can be used as transportation fuels. Natural gas is currently a readily available resource that has a positive future outlook considering its known and anticipated reserves. There is intense government and industrial interest in developing economic technologies to convert natural gas to liquid fuels. Methane, CH{sub 4}, is the primary hydrocarbon (85-95%) in natural gas. This document covers the following: production soluable of methane monooxygenase; production of particulate methane monooxygenase; production of methane monooxygenase in continuous culture; subunit resolution for active site identification of methylosinus trichosporium OB3b soluble methane monooxygenase; the synthesis and characterization of new copper coordination complexes contairing the asymmetric coordinating chelate ligand application to enzyme active site modeling; the synthesis and characterization of new iron coordination complexes utilizing an asymmetric coordinating chelate ligand; further characterization of new bionuclear iron complexes.
Date: July 1, 1995
Creator: Watkins, B.E.; Satcher, J.H. Jr.; Droege, M.W. & Taylor, R.T.
Partner: UNT Libraries Government Documents Department

Microbially-enhanced redox solution reoxidation for sweetening sour natural gas

Description: About twenty five percent of natural gas produced in the United States is sour containing significant volumes of hydrogen sulfide and other contaminants. Liquid redox processes remove hydrogen sulfide from natural gas. Aqueous solution of chelated ferric ions oxidize the hydrogen sulfide to elemental sulfur. The reduced iron chelate is then oxidized by contact with air and recycled. This requires expensive equipment for regeneration, costly chemicals and the process is usually energy intensive. Recent studies show that the ferric ion regeneration rates are substantially enhanced in presence of acidophilic bacteria. The specific objectives of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes utilizing biologically-enhanced reoxidation of the redox solutions used in these processes, such as LO-CAT II and SulFerox.
Date: June 1995
Creator: Rai, C.
Partner: UNT Libraries Government Documents Department


Description: The solubilities of uranyl dlbutyl phosphate, uranyl monobutyl phosphate, ferric dibutyl phosphate, and ferric monobutyl phosphate were measured in aqueous nitric acid solutions ranging from 0 to 3 M and in 30% TBP in Amsco 125-82 solution containing 0--0.7 M HNO/sub 3/. For the respective compounds in the aqueous phases, as the acidity increased from 0 to 3 M, the solubilities increased from 0.004 to 0.7 g U/liter, O.O5to 50 g U/liter, <1 to 30 mg Fe(III)/ liter, and 0.003 to 3 g Fe(III)/liter; corresponding solubilities in the organic phases increased with acidity from 14 to 165 g U/liter, 11 to 110 g U/liter, <O.5to 4 mg Fe(III)/liter, and <0.002 to 1.5 g Fe(III)/liter. All these compounds foamed or formed very flocculent solids in the aqueous phases snd tended to settle slowly in the organic phases and rise to the surface in the aqueous phases, suggesting that they would be interface seekers in two-phase aqueousorganic systems. (auth)
Date: May 1, 1961
Creator: Davis, W. Jr.
Partner: UNT Libraries Government Documents Department

1: Redox chemistry of bimetallic fulvalene complexes; 2: Oligocyclopentadienyl complexes

Description: The electrochemistry of the heterobimetallic complexes (fulvalene)WFe(CO){sub 5} (30) and (fulvalene)WRu(CO){sub 5} (31) has been investigated. Compound 30 is reduced in two one-electron processes, and this behavior was exploited synthetically to prepare a tetranuclear dimer by selective metal reduction. Complex 31 displayed a distinction between the metals upon reoxidation of the dianion, allowing the formation of a dimer by selective metal anion oxidation. The redox behavior of 30 led to an investigation of the use of electrocatalysis to effect metal-specific ligand substitution. It was found that reduction of 30 with a catalytic amount of CpFe(C{sub 6}Me{sub 6}) (97) in the presence of excess P(OMe){sub 3} or PMe{sub 3} led to the formation of the zwitterions (fulvalene)[W(CO){sub 3}{sup {minus}}][Fe(CO)PR{sub 3}{sup +}] (107, R = P(OMe){sub 3}; 108, R = PMe{sub 3}). Compound 31 also displayed unique behavior with different reducing agents, as the monosubstituted zwitterion (fulvalene)[W(CO){sub 3}{sup {minus}}][Ru(CO){sub 2}(PMe{sub 3}){sup +}] was obtained when 97 was used while the disubstituted complex (fulvalene) [W(CO){sub 3}{sup {minus}}] [Ru(CO)(PMe{sub 3}){sub 2}{sup +}] was produced when Cp*Fe(C{sub 6}Me{sub 6}) was the catalyst. Potential synthetic routes to quatercyclopentadienyl complexes were also explored. Various attempts to couple heterobimetallic fulvalene compounds proved to be unsuccessful. 138 refs.
Date: November 1, 1993
Creator: Brown, D. S.
Partner: UNT Libraries Government Documents Department

[Comparison of group transfer, inner shere and outer sphere electron transfer mechanisms for organometallic complexes]. Summary

Description: Our studies of reactions of metal carbonyl cations and anions have shown that metal carbonyl cations can catalyze CO exchange reactions on metal carbonyl anions. This result provides further evidence for a mechanism involving attack of the metal carbonyl anion on a carbon of the metal carbonyl cation in CO{sup 2+} transfer reactions. Reaction of metal carbonyl anions with metal carbonyl halides is a common approach to formation of metal-metal bonds. We have begun to use kinetic data and product analysis to understand the formation of homobimetallic versus heterobimetallic products in such reactions. Initial data indicate a nucleophilic attack, possibly through a ring-slippage mechanism.
Date: December 31, 1991
Partner: UNT Libraries Government Documents Department

Organometallic and Surface Chemistry of Mixed-Metal Systems. Progress Report, March 15, 1992--March 14, 1993

Description: Three new SO{sub 2} complexes of metal cluster compounds were prepared: [PPN][HFe{sub 3}(CO){sub 9}SO{sub 2}], and [PPN]{sub 2}[Ru{sub 3}CO{sub 9}SO{sub 2}] and [PPN]{sub 2}[Ru{sub 3}(CO){sub 7}(SO{sub 2}){sub 3}]. The x-ray structures were determined for two of these and the transformation of bound SO{sub 2} to duster bound SO and S ligands was investigated.
Date: April 1993
Creator: Shriver, D. F.
Partner: UNT Libraries Government Documents Department

Catalytic oxidation of hydrocarbons by dinuclear iron complexes. Progress report

Description: Our efforts during the past eight months were directed towards characterizing synthetic complexes that model the electronic and reactivity properties of the active site of methane monooxygenase (MMO), a metalloenzyme found in methanotrophic bacteria responsible for the biological oxidation of methane to methanol. We have investigated the structural/electronic and reactivity properties of a series of dinuclear model complexes that can function as oxygen atom transfer catalysts. In particular, our studies focused on [Fe{sup 2+}{sub 2}(H{sub 2}Hbab){sub 2}(N-MeIm){sub 2}], its DMF solvated form, [Fe{sup 2+}{sub 2}(H{sub 2}Hbab){sub 2}(DMF){sub 2}(MeIm)], and the mixed valent species [Fe{sup 2+}Fe{sup 3+}(H{sub 2}Hbab){sub 2}(DMF){sub 4}]{sup +}, (H{sub 4}Hbab = 1,2-bis(2-hydroxybenzamido) benzene). We have also examined [Fe{sup 3+}{sub 2}(H{sub 2}Hbab){sub 2}(DMF){sub 4}]{sup 2+}, [Fe{sup 3+}{sub 2}(H{sub 2}Hbab){sub 2}(OMe){sub 2}], and {mu}-oxo-[Fe{sup 3+}{sub 2}(H{sub 2}Hbab){sub 2}(DMF){sub 2]}, which are unable to act as oxygen atom transfer catalysts.
Date: December 31, 1992
Creator: Caradonna, J. P.
Partner: UNT Libraries Government Documents Department

Reductive coupling of carbon monoxide to C{sub 2} products. Progress report for the period, May 1, 1990--November 15, 1993

Description: This progress report covers the two broad areas of research addressed during the period since May 1, 1990. As proposed in 1989, studies of carbyne transformations have been pursued with a variety of carbyne substituents. Perhaps the most noteworthy carbyne results are also the simplest: preparation and properties of the parent M{triple_bond}CH unit. The other topic addressed with DOE support has metal nitrene chemistry as the cornerstone. Publications with iron, tungsten and copper complexes reflect our efforts to access intermediate oxidation state metal nitrene monomers. This new thrust was a central theme of the proposal submitted in 1989, and progress to date is sufficiently encouraging that detailed plans for expanding our nitrene project are an integral part of the accompanying proposal. References in this progress report are kept to a minimum; extensive references in the papers cited here place the work in perspective relative to the literature landscape.
Date: October 1, 1993
Creator: Templeton, J. L.
Partner: UNT Libraries Government Documents Department

Metallocarboxylate chemistry. Progress report, April 1, 1989--September 20, 1991

Description: CO{sub 2}-Bridged Bimetallics: Goals were to establish synthetic routes to metallocarboxylates, MCOOM` [M=CpFe(CO)(PPh{sub 3}) or Cp*Fe(CO)(PPh{sub 3}); M`=alakli, main or transition metal], to assess stability and to explore chemical reactions. Much of the efforts were focused on metallocarboxylate anions. Spectra (IR, DRIFTS, NMR) were studied. Other C{sub 1} Complexes: Other aspects of transition metal-C{sub 1} chemistry have been under investigation.
Date: December 31, 1991
Creator: Gibson, D. H.
Partner: UNT Libraries Government Documents Department

Thermally-generated reactive intermediates: Trapping of the parent ferrocene-based o-quinodimethane and reactions of diradicals generated by hydrogen-atom transfers

Description: Ferrocenocyclobutene is prepared by flash vacuum pyrolysis (FVP) of the N-amino-2-phenylaziridine hydrazone of 2-methylferrocenealdehyde. In the second section of this dissertation, a series of hydrocarbon rearrangements were observed. FVP of o-allyltoluene at 0.1 Torr (700--900 C) gives 2-methylindan and indene, accompanied by o-propenyltoluene. FVP of 2-methyl-2`-vinylbiphenyl gives 9-methyl-9,10-dihydrophenanthrene, which fits the proposed mechanism. However, FVP of 2-(o-methylbenzyl)styrene gives mainly anthracene and 1-methylanthracene. This cyclization reaction was also successful with o-allylphenol and o-(2-methylallyl)phenol.
Date: September 1, 1993
Creator: Ferguson, J. M.
Partner: UNT Libraries Government Documents Department

Metallocarboxylate chemistry. Progress report, November 17, 1992--November 22, 1993

Description: Research is focused on bimetallic compounds of late transition metals with carbon dioxide or CO{sub 2}-containing bridging ligands. The compounds are models for catalytic intermediates in CO{sub 2} fixation/activation processes. Thermolysis was studied. Re, Fe, and Sn complexes were studied.
Date: November 22, 1993
Creator: Gibson, D. H.
Partner: UNT Libraries Government Documents Department

Electrocatalysts for oxygen electrodes. Final report

Description: Object was to understand factors controlling the activity of O{sub 2} reduction and generation electrocatalysts, in order to attain higher activity and longer-term stability. Two broad classes of catalysts were developed: transition metal macrocycles in monomeric and polymeric forms, and transition metal oxides including perovskites and pyrochlores. 20 refs., 14 figs.
Date: February 1, 1993
Creator: Yeager, E.
Partner: UNT Libraries Government Documents Department