118 Matching Results

Search Results

Advanced search parameters have been applied.

Task 4.7 - diesel fuel desulfurization. Semi-annual report, July 1, 1995--December 31, 1995

Description: Reductions in the maximum permissible sulfur content of diesel fuel to less than 0.05 wt% will require deep desulfurization to meet these standards. In some refineries, a new hydrogenation catalyst may be required for diesel fuel production. The work very briefly described in this document is on the use of hydrotalcite-supported molybdenum sulfide in the catalysis of ethanol. The catalyst reaction was highly selective for 1-butanol, providing a very clean reaction. Since the catalysis contains the MoS{sub 2} needed for the dehydrogenation and hydrogenation steps, the reaction can be performed at lower temperatures and higher selectivity. The catalyst was very stable and not destroyed by the water produced in the reaction.
Date: December 31, 1998
Creator: Olson, E.S.
Partner: UNT Libraries Government Documents Department

Electrophoretically-deposited solid film lubricants

Description: An aqueous-based process that uses electrophoresis to attract powdered lubricant in suspension to a charged target was developed. The deposition process yields coatings with low friction, complies with environmental safety regulations, requires minimal equipment, and has several advantages over processes involving organic binders or vacuum techniques. This work focuses on development of the deposition process, includes an analysis of the friction coefficient of the material in sliding contact with stainless steel under a range of conditions, and a functional evaluation of coating performance in a precision mechanical device application. Results show that solid lubricant films with friction coefficients as low as 0.03 can be produced. A 0.03 friction coefficient is superior to solid lubricants with binder systems and is comparable to friction coefficients generated with more costly vacuum techniques.
Date: April 1, 1995
Creator: Dugger, M.T.; Panitz, J.K.J. & Vanecek, C.W.
Partner: UNT Libraries Government Documents Department

Absorbance and Photoluminescence of Si, Ge, and MoS{sub 2} Nanoparticles Studied by Liquid Chromatography

Description: The authors have successfully synthesized highly crystalline, size-selected indirect band-gap nanocrystals (NC) of Si, Ge and MoS{sub 2} in the size range 2-10 nm in inverse micelles and studied their optical absorption and photoluminescence (PL) properties using liquid chromatography. Room temperature, visible PL from these nanocrystals was demonstrated in the range 700-350 nm (1.8-3.5 eV). their experimental results are interpreted in terms of the corresponding electronic structure of the bulk materials and it is demonstrated that these nanocrystals retain bulk-like electronic character to sizes as small as 2 nm, but the absorbance energies are strongly blue-shifted by quantum confinement. The experimental results on Si-NCs are also compared to earlier work on Si clusters grown by other techniques and to the predictions of various model calculations. Currently, the wide variations in the theoretical predictions of the various models along with considerable uncertainties in experimental size determination for clusters less than 3-4 nm, make it difficult to select the best model.
Date: July 12, 1999
Creator: Provencio, P.P.; Samara, G.A. & Wilcoxon, J.P,
Partner: UNT Libraries Government Documents Department

Organusulfur Catalysis With Reduced Molybdenum Sulfides Containing the Mo6S8 Cluster

Description: Industrial synthesis of sulfur-containing organic chemicals basically focuses on the broad categories of mercaptans (thiols), alkylsulfides (thioethers), polysulfides, and thiophenes. Of the organo-sulfur compounds produced, by far the most important in terms of quantities produced is methyl mercaptan (methanethiol or MeSH), which is produced mainly for the downstream production of methionine and methanesulfonyl chloride. Higher thiols are also used in the manufacture of rubber and plastics as polymerization regulators, chain transfer agents, or initiators. Other important organosulfur chemicals are dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), both of which are used extensively for presulfiding of industrial hydroprocessing catalysts, and substituted thiophenes which are used as intermediates for production of agrochemicals, dyes, and pharmaceuticals. Thiols are produced commercially at the rate of about 10{sup 4} ton/yr from hydrogen sulfide (H{sub 2}S) and alcohols or olefins, using homogeneous free-radical synthesis, or heterogeneous catalysts based on solid acids or supported metal oxides and/or sulfides. Despite this large production rate, and the industrial importance of the organosulfur compounds, only limited research has been devoted to the development of new catalytic materials for their synthesis. Additionally, for most organosulfur catalytic reactions, only limited information exists about reaction mechanisms, active sites, adsorbed surface species, and especially the nature of the catalysts under reaction conditions.
Date: August 27, 2002
Creator: Paskach, Thomas Jay
Partner: UNT Libraries Government Documents Department

Preparation and friction characteristics of self-lubricating TiN- MoS{sub 2} composite coatings

Description: Composite coatings consisting of distinctly discrete phases of TiN and MoS{sub 2} were codeposited on graphite and Ti-6Al-4V substrates from Ti((CH3)2N)4/NH3/MoF6/H2S gas mixtures. Chemical composition and microstructure of the coatings were studied by Auger electron spectroscopy, XRD, and TEM. Friction coefficients at room temperature in air were typically in the range of 0.07 to 0.3; they remained comparable at 573 K, but increased to 0.7 to 1.0 at 673 K. A friction coefficient of {similar_to}0.3 was, however, obtained from a composite coating tested at 973 K.
Date: December 31, 1995
Creator: Bae, Y.W.; Lee, W.Y.; Besmann, T.M.; Yust, C.S. & Blau, P.J.
Partner: UNT Libraries Government Documents Department

Aging model for solid lubricants used in weapon stronglinks: tribological performance and hardware review

Description: The solid lubricant used most extensively in strong links throughout the enduring stockpile contains MoS{sub 2}, which is known to react with oxygen and water vapor resulting in a change in the material`s friction and wear behavior. The authors have examined the frictional behavior of this lubricant as a function of oxidation, in support of efforts to quantify the impact of changes in the material on the dynamic behavior of the MC2969 strong link. Their results show that the friction response of oxidized lubricant is strongly influenced by the amount of burnishing performed on the lubricant after deposition. Low levels of burnish leave a thick film, of which only the near surface degrades during oxidation. Rapid wear of the oxidized material leaves a surface whose properties are the same as non-oxidized material. Higher levels of burnish leave a thinner film of lubricant such that the entire film may be oxidized. The friction coefficient on this surface reaches a steady state value greater than that of non oxidized material. In addition to these fundamental differences in steady state behavior, they have shown that the initial friction coefficient on oxidized surfaces is related to the amount of sulfide converted to sulfate, regardless of the oxidation conditions used. Measurements on parts returned from the stockpile show that the friction behavior of aged hardware is consistent with the behavior observed on controlled substrates containing thin lubricant films.
Date: September 1, 1997
Creator: Dugger, M. T.; Peebles, D. E.; Sorroche, E. H.; Varga, K. S. & Bryan, R. M.
Partner: UNT Libraries Government Documents Department

Task 4.7 -- Diesel fuel desulfurization. Semi-annual report, January 1--June 30, 1995

Description: Reductions in the maximum permissible sulfur content of diesel fuel to less than 0.05 wt% will require deep desulfurization technologies to meet these standards. In some refineries, a new hydrogenation catalyst may be required for diesel fuel production. Some of the major components of diesel fuel are dibenzothiophenes and its alkyl derivatives. These components are desulfurized by the Rhodococcus rhodocrous IGTS8 enzymes. But when they are highly diluted with other hydrocarbons in the diesel fuel, will there be enough specificity for their absorption and degradation by the enzyme systems? The extent to which a diesel fuel or middle distillate feed can be desulfurized by desulfurization enzymes will be determined. In addition, the effectiveness of molybdenum sulfide catalysts in removing sulfur from the middle distillate cut will be determined. The catalyst preparation involves creation of the molybdenum sulfide in a highly dispersed form essentially between the layers of a hydrotalcite material, which is then dissolved away to expose the active sites.
Date: August 1, 1997
Creator: Olson, E.S.
Partner: UNT Libraries Government Documents Department

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Technical progress report, October 1992--December 1992

Description: The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of manometer size is being carried out. It is based on the molecular design of reverse micelles (microemulsions). These surfactant-stabilized, metal-bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limits particle nucleation, growth and agglomeration. The emphasis is on molybdenum- and iron-based catalysts, but the techniques being developed should also be generally applicable. The size of these very small and monodispersed particles will be accurately determined both separately and after in situ and ex situ coal impregnation. The as-prepared nanoparticles as well as the catalyst-impregnated coal or char matrix are characterized using a battery of techniques, including dynamic light scattering, x-ray diffraction and transmission electron microscopy. Catalytic activity tests are conducted under standardized coal liquefaction conditions. The effect of particle size of these unsupported catalysts on the product yield and distribution during conversion of a bituminous and a subbituminous coal are being determined.In this quarter, the synthesis of molybdenum sulfide in a microemulsion system with an alcohol-to-surfactant mass ratio of 3.5 is reported.
Date: February 1, 1993
Creator: Boakye, E.; Vittal, M. & Osseo-Asare, K.
Partner: UNT Libraries Government Documents Department

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Technical progress report, July 1992--September 1992

Description: The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of manometer size will be carried out. It is based on the molecular design of reverse micelles (microemulsions). These surfactant-stabilized, metal-bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limits particle. nucleation, growth and agglomeration. The emphasis will be on iron- and molybdenum-based catalysts, but the techniques to be developed should also be generally applicable. The size of these very small and monodispersed particles will be accurately determined both separately and after in situ and ex situ coal impregnation. The as-prepared nanoparticles as well as the catalyst-impregnated coal or char matrix will be characterized using the following techniques: dynamic light scattering, x-ray diffraction, x-ray photoelectron spectroscopy, scanning and/or transmission electron microscopy, and selective chemisorption. Catalytic activity tests will be conducted under standardized conditions in both hydrogenation and hydrodesulfurization reactions. The effect of particle size of these unsupported catalysts on the product yield and distribution during liquefaction of a bituminous and a subbituminous coal will thus be quantitatively determined.
Date: October 1, 1992
Creator: Boakye, E.; Vittal, M. & Osseo-Asare, K.
Partner: UNT Libraries Government Documents Department

Studies of photoredox reactions on nanosize semiconductors

Description: Light induced electron transfer (ET) from nanosize semiconductors of MoS{sub 2} to organic electron acceptors such as 2,2{prime}-bipyridine (bpy) and methyl substituted 4,4{prime},5,5{prime}-tetramethyl-2,2{prime}-bipyridine (tmb) was studied by static and time resolved photoluminescence spectroscopy. The kinetics of ET were varied by changing the nanocluster size (the band gap), the electron acceptor, and the polarity of the solvent. MoS{sub 2} is an especially interesting semiconductor material as it is an indirect semiconductor in bulk form, and has a layered covalent bonding arrangement which is highly resistant to photocorrosion. Et occurs following photoexcitation of the direct band gap. Quantum confinement results in the smaller nanoclusters having higher conduction band energies, and therefore larger ET driving forces. The ET reaction energies may be varied by changing the electron acceptor, by varying the size of the MoS{sub 2} nanocluster or by varying the polarity of the solvent. In addition, varying the polarity of the solvent affects the reorganization energy and the barrier to electron transfer. TMB is harder to reduce, and thus has a smaller ET driving force than bpy. The solvent polarity is varied by varying the composition of acetonitrile/benzene mixed solvents.
Date: August 1, 1997
Creator: Wilcoxon, J.P.; Parsapour, F. & Kelley, D.F.
Partner: UNT Libraries Government Documents Department

THE ECONOMICAL PRODUCTION OF ALCOHOL FUELS FROM COAL-DERIVED SYNTHESIS GAS. Includes quarterly technical progress report No.25 from 10/01/1997-12/31/1997, and quarterly technical progress report No.26 from 01/01/1998-03/31/1998

Description: This project was divided into two parts. One part evaluated possible catalysts for producing higher-alcohols (C{sub 2} to C{sub 5+}) as fuel additives. The other part provided guidance by looking both at the economics of mixed-alcohol production from coal-derived syngas and the effect of higher alcohol addition on gasoline octane and engine performance. The catalysts studied for higher-alcohol synthesis were molybdenum sulfides promoted with potassium. The best catalysts produced alcohols at a rate of 200 g/kg of catalyst/h. Higher-alcohol selectivity was over 40%. The hydrocarbon by-product was less than 20%. These catalysts met established success criteria. The economics for mixed alcohols produced from coal were poor compared to mixed alcohols produced from natural gas. Syngas from natural gas was always less expensive than syngas from coal. Engine tests showed that mixed alcohols added to gasoline significantly improved fuel quality. Mixed-alcohols as produced by our catalysts enhanced gasoline octane and decreased engine emissions. Mixed-alcohol addition gave better results than adding individual alcohols as had been done in the 1980's when some refiners added methanol or ethanol to gasoline.
Date: March 1, 1999
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

Lubricant replacement in rolling element bearings for weapon surety devices

Description: Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.
Date: May 1, 1996
Creator: Steinhoff, R.; Dugger, M.T. & Varga, K.S.
Partner: UNT Libraries Government Documents Department

Synthesis and optical properties of MoS{sub 2} nanoclusters

Description: Highly crystalline nanoclusters of MoS{sub 2} were synthesized and their optical absorption and photoluminescence spectra were investigated. Key results include: (1) strong quantum confinement effects with decreasing size; (2) preservation of the quasiparticle (or excitonic) nature of the optical response for clusters down to {approximately} 2.5 nm in size which are only two unit cells thick; (3) demonstration that 3-D confinement produces energy shifts which are over an order of magnitude larger than those due to 1-D confinement; (4) observation of large increases in the spin-orbit splittings at the top of the valence band at the K and M points of the Brillouin zone with decreasing cluster size; and (5) observation of photoluminescence due to both direct and surface recombination. Application is to photocatalysts for solar fuel production and detoxification of chemical waste.
Date: December 1, 1996
Creator: Wilcoxon, J.P.; Newcomer, P.P. & Samara, G.A.
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

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

Task 4.9 -- Value-added products from syngas. Semi-annual report, July 1--December 31, 1996

Description: The work on advanced fuel forms in 1996 focused on the synthesis of higher alcohols from mixtures of hydrogen and carbon dioxide (syngas) from coal gasification. Initial work in this project utilized a novel molybdenum sulfide catalyst previously shown to be active for hydrodesulfurization reactions of coal liquids. A pressurized fixed-bed flow-through reactor was constructed, and the MoS{sub 2} catalysts were tested with syngas under a variety of conditions. Unfortunately, the catalysts, even with higher molybdenum loading and addition of promoters, failed to give alcohol products. A batch reactor test of the catalyst was also conducted, but did not produce alcohol products. Group VIII metals have been used previously in catalysts for syngas reactions. Ruthenium and rhodium catalysts were prepared by impregnation of a hydrotalcite support. Tests with these catalysts in flow-through reactors also did not produce the desired alcohol products. The formation of higher alcohols from smaller ones, such as methanol and ethanol, could be commercially important if high selectivity could be achieved. The methanol and ethanol would be derived from syngas and fermentation, respectively. Based on previous work in other laboratories, it was hypothesized that the hydrotalcite-supported MoS{sub 2} or Ru or Rh catalysts could catalyze the formation of butyl alcohols. Although the desired 1-butanol was obtained in batch reactions with the promoted ruthenium catalyst, the reaction was not as selective as desired. Product suitable for a lower-vapor-pressure gasoline oxygenate additive was obtained, but it may not be economical to market such products in competition with methyl tertiary-butyl ether (MTBE). Flow-through catalytic bed reactions were not successful.
Date: August 1, 1997
Creator: Olson, E.S. & Sharma, R.K.
Partner: UNT Libraries Government Documents Department

New catalysts for coal processing: Metal carbides and nitrides. Third semiannual report, July 17, 1996--January 17, 1996

Description: Unsupported molybdenum nitride (Mo{sub 2}N) and molybdenum carbide supported on alumina (Mo{sub 2}C/Al{sub 2}O{sub 3}) were compared against commercial sulfided MoS{sub 2}/Al{sub 2}O{sub 3} and Ni-Mo-S/Al{sub 2}O{sub 3} for hydrotreating coal-derived gas oil at 633 K (360 {degrees}C) and 13.7 MPa (2000 psig). When the catalytic rates were compared on the basis of active sites measured by chemisorption, the nitrides and carbides were estimated to have activities as much as five times that of Ni-Mo-S/Al{sub 2}O{sub 3} and MoS{sub 2}/Al{sub 2}O{sub 3}. The comparison was based on sites titrated by CO on the carbide and nitride and by O{sub 2} on the sulfided catalysts. The gas oil product quality from the carbide and nitride catalysts was significantly better than the thermal blank, indicating that the materials were active under practical hydrotreating conditions. X-ray photoelectron spectroscopy analysis after reaction of the Mo{sub 2}N and Mo{sub 2}C/Al{sub 2}O{sub 3} catalysts indicated that surface sulfiding was not extensive.
Date: January 5, 1997
Creator: Oyama, S.T. & Cox, D.F.
Partner: UNT Libraries Government Documents Department

Final Report: Catalytic Hydrocarbon Reactions over Supported Metal Oxides, August 1, 1995 - July 31, 1999

Description: The research program focused on the catalysis of hydrodesulfurization (HDS) over molybdenum-based catalysts and how catalyst composition, redox ability, structure and neighboring sites control the catalytic properties of metal oxides. We sought to understand the catalytic features/sites that control hydrogenation, hydrogenolysis, and isomerization during HDS. Unprompted silica-supported molybdenum oxides and molybdenum sulfides were studied. Model catalyst systems were prepared from organometallic precursors or cluster compounds to generate supported structures that feature Mo(II) and Mo(IV) cations that are isolated or in ensembles and that have either Mo-O or Mo-S bonds. Conventional MOS{sub 2} catalysts, which contain both edge and rim sites, were be studied. Finally, single-layer MOS{sub 2} structures were also prepared from 2H-MoS{sub 2} powder so that the model systems could be compared against a disulfide catalyst that only involves rim sites. Catalytic reactions for thiophene and tetrahydrothione were studied over the various catalysts. Oxidation states were determined using X-ray photoelectron spectroscopy. X-ray crystallography was used to characterize and follow changes in the MOS{sub 2} structures. The program on metal oxides prepared supported oxides that have a specific structure and oxidation state to serve as model templates for the more complex commercial catalysts and then employed these structures in reaction studies. This focus area examined the relationships between structure and cation redox characteristics in oxidation catalysis. Infrared and Raman spectroscopy were used to characterize the cations and reaction intermediates.
Date: July 31, 1999
Creator: Ekerdt, John G.
Partner: UNT Libraries Government Documents Department

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Technical progress report, January 1992--March 1992

Description: The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of manometer size will be carried out. It is based on the molecular design of reverse micelles (microemulsions). These surfactant-stabilized, metal-bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limits particle nucleation, growth and agglomeration. The emphasis will be on iron- and molybdenum-based catalysts, but the techniques to be developed should also be generally applicable. The size of these very small and monodispersed particles will be accurately determined both separately and after in situ and ex situ coal impregnation. The as-prepared nanoparticles as well as the catalyst-impregnated coal or char matrix will be characterized using the following techniques: dynamic light scattering, x-ray diffraction, x-ray photoelectron spectroscopy, scanning and/or transmission electron microscopy, and selective chemisorption. Catalytic activity tests will be conducted under standardized conditions in both hydrogenation and hydrodesulfurization reactions. The effect of particle size of these unsupported catalysts on the product yield and distribution during liquefaction of a bituminous and a subbituminous coal will thus be quantitatively determined.
Date: May 1, 1992
Creator: Osseo-Asare, K.; Boakye, E. & Radovic, L.R.
Partner: UNT Libraries Government Documents Department

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Technical progress report, January 1993--March 1993

Description: The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of manometer size is being carried out. It is based on the molecular design of reverse micelles (microemulsions). These surfactant-stabilized, metal-bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limits particle nucleation, growth and agglomeration. The emphasis is on molybdenum- and iron-based catalysts, but the techniques being developed should also be generally applicable. The size of these very small and monodispersed particles will be accurately determined both separately and after in situ and ex situ coal impregnation. The as-prepared nanoparticles as well as the catalyst-impregnated coal or char matrix are characterized using a battery of techniques, including dynamic light scattering, x-ray diffraction and transmission electron microscopy. Catalytic activity tests are conducted under standardized coal liquefaction conditions. The effect of particle size of these unsupported catalysts on the product yield and distribution during conversion of a bituminous and a subbituminous coal are being determined. This quarter, the solubilization of ammonium tetrathiomolybdate and the synthesis of molybdenum sulfide in several microemulsion systems is discussed.
Date: April 1, 1993
Creator: Boakye, E.; Vittal, M. & Osseo-Asare, K.
Partner: UNT Libraries Government Documents Department

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Technical progress report, April 1993--June 1993

Description: The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of manometer size is being carried out. It is based on the molecular design of inverse micelles (microemulsions). These surfactant-stabilized, metal-bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limits particle nucleation, growth and agglomeration. The emphasis is on molybdenum- and iron-based catalysts, but the techniques being developed should also be generally applicable. The size of these very small and monodispersed particles will be accurately determined both separately and after in situ and ex situ coal impregnation. The as-prepared nanoparticles as well as the catalyst-impregnated coal matrix are characterized using a battery of techniques, including g dynamic light scattering, x-ray diffraction and transmission electron microscopy. Catalytic activity tests are conducted under standardized coal liquefaction conditions. The effects of particle size of these unsupported catalysts on the product yield and distribution during conversion of a bituminous and a subbituminous coal are being determined. This report discusses molybdenum sulfide particle synthesis, characterization, and microemulsion characterization.
Date: July 1, 1993
Creator: Boakye, E.; Vittal, M. & Osseo-Asare, K.
Partner: UNT Libraries Government Documents Department

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Technical progress report, July--September 1993

Description: The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of manometer size is being carried out. It is based on the molecular design of inverse micelles (microemulsions). These surfactant-stabilized, metal-bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limits particle nucleation, growth and agglomeration. The emphasis is on molybdenum- and iron-based catalysts, but the techniques being developed should also be generally applicable. The size of these very small and monodispersed particles will be accurately determined both separately and after in situ and ex situ coal impregnation. The as-prepared nanoparticles as well as the catalyst-impregnated coal matrix are characterized using a battery of techniques, including dynamic light scattering, x-ray diffraction and transmission electron microscopy. Catalytic activity tests are conducted under standardized coal liquefaction conditions. The effects of particle size of these unsupported catalysts on the product yield and distribution during conversion of a bituminous and a subbituminous coal are being determined.
Date: October 1, 1993
Creator: Boakye, E.; Vittal, M. & Osseo-Asare, K.
Partner: UNT Libraries Government Documents Department