75 Matching Results

Search Results

Advanced search parameters have been applied.

Characteristics of CoxTi1-xO2 thin films deposited by MOCVD

Description: This paper deals with the growth and characterization of ferromagnetic cobalt doped TiO{sub 2} thin films deposited by liquid precursor metal organic chemical vapor deposition (MOCVD) using a new combination of the source materials Co(TMHD){sub 3}, tetrahydrofuran (THF), and titanium isopropoxide (TIP). An array of experiments reveals the intrinsic ferromagnetic nature of the grown films, and suggests that the magnetism is not generated by oxygen vacancies.
Date: May 9, 2008
Creator: McClure, A.; Kayani, A.; Idzerda, Y.U.; Arenholz, E. & Cruz, E.
Partner: UNT Libraries Government Documents Department

Photochemical coal dissolution. Final technical progress report, September 30, 1993--September 29, 1996

Description: A flowing solvent photochemical reactor was designed, built and tested. A modified ACE photochemical reactor, lamp and power supply were employed. They were modified to accommodate a silica column-constrained dispersed coal sample and a solvent flowing through the silica/coal column to sweep away coal extract. Before each experiment the column was packed with the mixture of silica and coal in the annular space around the lamp. A reflective aluminum surface (foil) reflected any light-transmitted through the column for multiple passes back through the sample. A variable speed Rainin Rabbit Plus peristaltic pump was interfaced to an IBM XT computer via a Gilson RS232/RS422 converter. The purpose of the computer control was to vary the speed of the pump so as to control the absorbance of the solution of coal extract in the solvent. Absorbances at a chosen wavelength were measured by a Spec 21 spectrophotometer with a flow cell connected to the column effluent port. A signal proportional to transmittance from the Spec 21 was delivered to the computer through a Keithley DAS 801 A/D plug-in the computer. The analysis of the Spec 21 signal and control of the pump speed was based on a QuickBasic computer program written by us.
Date: May 1, 1997
Creator: Doetschman, D.C.
Partner: UNT Libraries Government Documents Department

Determination of unconverted HDPE in coal/plastics co-liquefaction stream samples

Description: In several coal/plastics liquefaction runs performed by Hydrocarbon Technologies, Inc. (HTI), a substantial amount of incompletely converted high-density polyethylene (HDPE) was present in ash-free recycle resid streams when either the ROSE-SR unit was used in Run POC-2, or the pressure filter unit was used in Runs CMSL-8 and CMSL-9. This indicates that the HDPE is less reactive than coal at the liquefaction conditions used. In these ash-free streams, there is no solid organic or inorganic material arising from the coal, and the incompletely converted HDPE can be recovered by extraction and filtration with tetrahydrofuran (THF) at room temperature. The HDPE (or HDPE-like material, which could also consist of heavy waxes) is THF insoluble. However, in ashy streams, there are both inorganic ({open_quotes}ash{close_quotes}) and organic (unconverted coal) components present from liquefaction of the coal, that interfere with an easy and clean separation of the HDPE from the coal/plastics liquefaction stream sample. Therefore, CONSOL developed an analytical procedure for HDPE in the ashy stream samples based on extraction of HDPE from the sample using hot (150{degrees}C) decalin (decahydronaphthalene), in which the HDPE is soluble. The decalin extraction is both preceded and succeeded by extractions and washes with THF at room temperature, to remove the coal-derived components from the sample.
Date: December 31, 1996
Creator: Robbins, G.A.; Winschel, R.A. & Burke, F.P.
Partner: UNT Libraries Government Documents Department

Self-organization of OPV-PEG diblock copolymers in THF/water.

Description: Oligo(phenylenevinylene)-poly(ethyleneglycol) (OPV-PEG) diblock copolymers in tetrahydrofuran (THF) solution at concentrations of 5 to 25 gl self-assemble into rod-like structures with a radius of about 80 {angstrom} for an OPV-PEG diblock copolymer comprising 13 PV and 45 EG monomers. These aggregates consist of a liquid crystalline OPV core and a PEG shell. Addition of about 10% water to the solution induces the formation of a phase of packed rods, as revealed by a sudden and dramatic transition of the scattering pattern. Further addition of water leads to swelling and at about 30% ultimately to disruption of the packed-rod phase.
Date: July 2, 1999
Creator: Jurban, V.; Littrell, K. C.; Thiyagarajan, P.; Wang, H. B.; Wang, H. H. & Yu, L.
Partner: UNT Libraries Government Documents Department

27Al and 1H Solid State NMR Studies Show Evidence of TiAl3 and TiH2 in Ti-doped NaAlH4

Description: Previous X-ray Diffraction (XRD) and Nuclear Magnetic Resonance (NMR) studies on Ti-doped NaAlH{sub 4} revealed the reaction products of two heavily doped (33.3 at.%) samples that were solvent-mixed and mechanically-milled. This investigation revealed that nano-crystalline or amorphous Al{sub 2}O{sub 3} forms from the possible coordination of aluminum with oxygen atom of the furan ring system from added tetrahydrofuran (THF) in the solvent-mixed sample, and that TiAl{sub 3} forms in mechanically-milled samples. The present paper provides a more sophisticated NMR investigation of the these materials. On heavily doped (33.3 at.%) solvent-mixed samples, {sup 27}Al Magic Angle Spinning (MAS) NMR {sup 27}Al multiple quantum MAS (MQMAS) indicates the presence of an oxide layer of Al{sub 2}O{sub 3} on the surfaces of potentially bulk nanocrystalline Ti, nanocrystalline TiAl{sub 3}, and/or metallic aluminum. The {sup 1}H MAS NMR data also indicate the possible coordination of aluminum with the oxygen atom in the THF. On heavily doped samples that were mechanically milled, {sup 27}Al MAS NMR and static NMR confirms the presence of TiAl{sub 3}. In addition, the {sup 1}H MAS NMR and {sup 1}H spin-lattice relaxation (T{sub 1}) measurements are consistent with the presence of TiH{sub 2}. These results are in agreement with recent XAFS measurements indicating both Al and H within the first few coordination shells of Ti in the doped alanate.
Date: May 26, 2005
Creator: Herberg, J; Maxwell, R & Majzoub, E
Partner: UNT Libraries Government Documents Department

Early actinide organonitrile compounds and their reactivity.

Description: The actinide trihalides are an important class of materials . Anhydrous AnX3 compounds have been prepared via high temperature synthetic techniques, but they exis t as polymeric solids, which are insoluble in organic solvents . 1-3 Transuranic complexe s AnI3(THF)X have been prepared by the reaction of metals with CZH4IZ in THF solution s (An = Pu, x = 5; An = Np, x = 4) 4 and can be viewed as a net oxidation of An metal wit h 1 .5 equivalents molecular iodine. A convenient preparation of organic solvent soluble trivalent actinide compounds has been described where 1 .5 equivalents of IZ are added t o actinide (An) metal turnings (An = Pu, U, Np) suspended in aprotic organic coordinatin g solvent. 5,6 Since virtually all nonaqueous An(III) complexes have been prepared throug h the triodide-tetrahydrofuran complex, we are interested in preparing complexes wit h solvents other than tetrahydrofuran . And, since uranium is often used as a surrogate for studying the chemistry of transuranic actinides, we are seeking to elucidate the chemical differences between the transuranic elements and uranium .
Date: January 1, 2003
Creator: Enriquez, A. E. (Alejandro E.); Matonic, J. H. (John H.); Scott, B. L. (Brian L.) & Neu, M. P. (Mary P.)
Partner: UNT Libraries Government Documents Department

Coordination Compounds of Strontium. Syntheses, Characterizations, and Crystal Structures of [Sr(u-ONc)(2)(HONc(4))]2 and Sr(5)(u(4)-O)(u(3)-ONep)(4)(u-ONep)(4)(HONep)(solv)(4) (ONc=O(2)CCH(2)CMe(3));Nep=CH(2)CMe(3); solv=tetrahydrofuran or 1-methyl-imida

Description: The authors have synthesized and characterized two novel Sr compounds: [Sr({mu}-ONc){sub 2}(HONc){sub 4}]{sub 2} (1, ONc = O{sub 2}CCH{sub 2}CMe{sub 3}), and Sr{sub 5}({mu}{sub 4}-O)({mu}{sub 3}-ONep){sub 4}({mu}-ONep){sub 4}(HONep)(solv){sub 4} [ONep = OCH{sub 2}CMe{sub 3}, solv = tetrahydrofuran (THF), 2a; 1-methyl-imidazole (MeIm), (2b)], that demonstrate increased solubility in comparison to the commercially available Sr precursors. The two metal centers of 1 share 4 unidentate bridging {mu}-ONc ligands and complete their octahedral geometry through the coordination of 4 monodentate terminal HONc ligands. The structure arrangement of the central core of 2a and b are identical, wherein 4 octahedral Sr atoms are arranged in a square geometry around a {mu}{sub 4}-O ligand. An additional 7-coordinated Sr atom sits directly atop the {mu}{sub 4}-O to form a square base pyramidal arrangement of the Sr atoms but the apical Sr-O distance is too long to be considered a bond. In solution, compound 1 is disrupted forming a monomer but 2a and b retain their structures.
Date: July 21, 1999
Creator: Boyle, Timothy J.; Tafoya, Cory J.; Scott, Brian L. & Ziller, Joseph W.
Partner: UNT Libraries Government Documents Department

Process and analytical studies of enhanced low severity co-processing using selective coal pretreatment. Quarterly technical progress report, June--August 1990

Description: This report describes progress on research during the seventh quarter of this contract dealing with applications of coal pretreatment techniques in coal hydroliquefaction. The objectives of the project are to investigate various coal pretreatment techniques and to determine the effect of these pretreatment procedures on the reactivity of the coal. Reactivity enhancement will be evaluated under both direct hydroliquefaction and co-processing conditions. Coal conversion utilizing low rank coals and low severity conditions (reaction temperatures generally less than 350 {degrees}C) are the primary focus of the liquefaction experiments, as it is expected that the effect of pretreatment conditions and the attendant reactivity enhancement will be greatest for these coals at these conditions.
Date: December 31, 1990
Creator: Baldwin, R. M. & Miller, R. L.
Partner: UNT Libraries Government Documents Department

Configurational diffusion of asphaltenes in fresh and aged catalyst extrudates. Quarterly progress report, December 20, 1995--March 20, 1996

Description: The objective of this research is to determine the relationship between the size and shape of coal and petroleum macromolecules and their diffusion rates i.e., effective diffusivities, in catalyst pore structures. That is, how do the effective intrapore diffusivities depend on molecule configuration and pore geometry? This quarter, adsorptive diffusion of both coal and petroleum asphaltenes in THF into porous catalysts were performed. A mathematical model with linear adsorption isotherm for asphaltene diffusion was developed. The molecular weight distribution of both asphaltenes were ascertained by GPC using polystyrene standards. The asphaltene diffusion data were simulated fairly well by the mathematical model, and linear adsorption constants were obtained for asphaltene fractions with different equivalent polystyrene molecular weights.
Date: July 1, 1996
Creator: Guin, J.A.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of waste Tank 241-SX-106: Results from samples collected on 3/24/95

Description: This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-SX-106 (referred to as Tank SX-106). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water (H{sub 2}O). Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, quantitative results were obtained for the 39 TO-14 compounds plus an additional 14 analytes. Of these, 4 were observed above the 5-ppbv reporting cutoff. Three tentatively identified compounds (TICs) were observed above the reporting cutoff of (ca.) 10 ppbv and are reported with concentrations that are semiquantitative estimates based on internal-standard response factors. The 7 organic analytes identified are listed in Table 1 and account for approximately 100% of the total organic components in Tank SX-106. Carbon dioxide (CO{sub 2}) was the only permanent gas detected. Tank SX-106 is on the Ferrocyanide Watch List.
Date: November 1, 1995
Creator: Klinger, G.S.; Clauss, T.W. & Litgotke, M.W.
Partner: UNT Libraries Government Documents Department

Results of Tritium Tracking and Groundwater Monitoring at the Hanford Site 200 Area State-Approved Land Disposal Site-FY1999

Description: The Hanford Site 200 Area Effluent Treatment Facility (ETF) processes contaminated liquids derived from Hanford Site facilities. The clean water generated by these processes is occasionally enriched in tritium and is discharged to the 200 Area State Approved Land Disposal Site (SALDS). Groundwater monitoring for tritium and other constituents is required by the state-issued permit at 21 wells surrounding the facility. During FY 1999, average tritium activities in most wells declined from average activities in 1998. The exception was deep well 69948-77C, where tritium results were at an all-time high (77,000 pCi/L) as a result of the delayed penetration of effluent deeper into the aquifer. Of the 12 constituents with permit enforcement limits, which are monitored in SALDS proximal wells, all were within limits during FY 1999. Water level measurements in nearby wells indicate that a small hydraulic mound exists around the SALDS facility as a result of discharges. This feature is directing groundwater flow radially outward a short distance before the regional northeasterly flow predominates. Evaluation of this condition indicates that the network is currently adequate for tracking potential effects of the SALDS on the groundwater. Recommendations include the discontinuation of ammonia, benzene, tetrahydrofuran, and acetone from the regular groundwater constituent list; designating background well 299-W8-1 as a tritium-tracking well only, and the use of quadruplicate averages of field pH, instead of a single laboratory measurement, as a permit compliance parameter.
Date: October 20, 1999
Creator: Barnett, D.B.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of waste Tank 241-B-103: Results from samples collected on 2/8/95

Description: This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-B-103 (referred to as Tank B-103). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water vapor (H{sub 2}O). Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, quantitative results were obtained for the 39 TO-14 compounds plus an additional 14 analytes. Of these, five were observed above the 5-ppbv reporting cutoff. Twenty-six organic tentatively identified compounds (TICs) were observed above the reporting cutoff of (ca.) 10 ppbv, and are reported with concentrations that are semiquantitative estimates based on internal standard response factors. Twenty-three TICs were measured in two or more SUMMA{trademark} canisters. The 10 organic analytes with the highest estimated concentrations are listed in Table 1 and account for approximately 66% of the total organic components in Tank BB-103. Two permanent gases, carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O), were also detected. Tank B-103 is on the Organic Watch List.
Date: October 1, 1995
Creator: Ligotke, M.W.; Pool, K.H. & Lucke, R.B.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of Waste Tank 241-S-111: Results from samples collected on 3/21/95

Description: This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-S-111 (referred to as Tank S-111). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water (H{sub 2}O). Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, quantitative results were obtained for the 39 TO-14 compounds plus an additional 14 analytes. Of these, seven were observed above the 5-ppbv reporting cutoff. Five tentatively identified compounds (TICs) were observed above the reporting cutoff of (ca.) 10 ppbv and are reported with concentrations that are semiquantitative estimates based on internal-standard response factors. The 10 organic analytes with the highest estimated concentrations are listed in Table 1 and account for approximately 98% of the total organic components in Tank S-111. Two permanent gases, hydrogen (H{sub 2}) and nitrous oxide (N{sub 2}O), were also detected. Tank S-111 is on the Hydrogen Watch List.
Date: October 1, 1995
Creator: Klinger, G.S.; Clauss, T.W. & Ligotke, M.W.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of waste Tank 241-BY-103: Results from samples collected on 11/1/94

Description: This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-BY-103 (referred to as Tank BY-103). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water (H{sub 2}O). Trends in NH{sub 3} and H{sub 2}O samples indicated a possible minor sampling problem. Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, quantitative results were obtained for target organic analytes, 39 TO-14 compounds, plus an additional 14 analytes. Of these, four were observed above the 5-ppbv reporting cutoff. Fourteen organic tentatively identified compounds (TICs) were observed above the reporting cutoff of (ca.) 10 ppbv, and are reported with concentrations that are semiquantitative estimates based on internal-standard response factors. The 10 organic analytes with the highest estimated concentrations are listed in Table 1 and account for approximately 88% of the total organic components in Tank BY-103. Two permanent gases, carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O), were also detected in the tank headspace. Carbon monoxide (CO) and carbon dioxide (CO{sub 2}) were detected in the ambient air sample. Tank BY-103 is on the Ferrocyanide Watch List.
Date: October 1, 1995
Creator: McVeety, B.D.; Klinger, G.S. & Clauss, T.W.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of Waste Tank 241-U-105: Results from samples collected on 2/24/95

Description: This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-U-105 (referred to as Tank U-105). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water (H{sub 2}O). Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, quantitative results were obtained for the 39 TO-14 compounds plus an additional 14 analytes. Of these, six were observed above the 5-ppbv reporting cutoff. Three tentatively identified compounds (TICs) were observed above the reporting cutoff of (ca.) 10 ppbv and are reported with concentrations that are semiquantitative estimates based on internal-standard response factors. All nine of the organic analytes identified are listed in Table 1 and account for 100% of the total organic components in Tank U-105. Nitrous oxide (N{sub 2}O) was the only permanent gas detected in the tank-headspace sample. Tank U-105 is on the Hydrogen Watch List.
Date: October 1, 1995
Creator: Pool, K.H.; Clauss, T.W. & Ligotke, M.W.
Partner: UNT Libraries Government Documents Department

Vapor space characterization of waste Tank 241-BY-108: Results from samples collected on 10/27/94

Description: This report describes inorganic and organic analyses results from samples obtained from the headspace of the Hanford waste storage Tank 241-BY-108 (referred to as Tank BY-108). The results described here were obtained to support safety and toxicological evaluations. A summary of the results for inorganic and organic analytes is listed in Table 1. Detailed descriptions of the results appear in the text. Quantitative results were obtained for the inorganic compounds ammonia (NH{sub 3}), nitrogen dioxide (NO{sub 2}), nitric oxide (NO), and water vapor (H{sub 2}O). Trends in NH{sub 3} and H{sub 2}O samples indicated a possible sampling problem. Sampling for hydrogen cyanide (HCN) and sulfur oxides (SO{sub x}) was not requested. In addition, the authors looked for the 40 TO-14 compounds plus an additional 15 analytes. Of these, 17 were observed above the 5-ppbv reporting cutoff. Also, eighty-one organic tentatively identified compounds (TICs) were observed above the reporting cutoff (ca.) 10 ppbv, and are reported with concentrations that are semiquantitative estimates based on internal standard response factors. The nine organic analytes with the highest estimated concentrations are listed in Summary Table 1 and account for approximately 48% of the total organic components in the headspace of Tank BY-108. Three permanent gases, hydrogen (H{sub 2}), carbon dioxide (CO{sub 2}), and nitrous oxide (N{sub 2}O) were also detected. Tank BY-108 is on the Ferrocyanide Watch List.
Date: October 1, 1995
Creator: McVeety, B.D.; Clauss, T.W. & Ligotke, M.W.
Partner: UNT Libraries Government Documents Department

Hydrogen Storage Properties of the Tetrahydrofuran Treated Magnesium

Description: The electronic structure, crystalline feature and morphology of the tetrahydrofuran (THF) treated magnesium, along with its hydriding and dehydriding properties have been investigated. The THF treated magnesium absorbs 6.3 wt per cent hydrogen at 723K and 3.5 MPa. After hydrogenation, in addition to the expected MgH2, a new less-stable hydride phase appears at 673K, but not at a lower temperature. Desorption produces 5.5 wt per cent hydrogen at 723K against a back pressure of 1.3 Pa after 20 cycles of hydriding-dehydriding. The THF treatment improves the kinetics of hydrogen absorption and desorption significantly. From 723K to 623K, the THF treated Mg demonstrates acceptable reaction rates. XPS studies show that tetrahydrofuran treatment causes the electronic energy state of the magnesium surface atoms to change, but the XRD studies show the crystal structure remains unchanged. Metallographic observation of the bulk hydrides of THF treated magnesium reveal they are poly-crystalline wi th the wide-spreading slip bands and twins within the crystals, indicating the phase transformation upon hydriding causes serious stress and distortion. It appears this microstructural deformation explains the much higher energy requirements (higher pressure and temperature) for magnesium hydrogenation than the simple lattice expansion that accompany hydrogen uptake for LaNi5 and FeTi.
Date: May 25, 2004
Creator: AU, MING
Partner: UNT Libraries Government Documents Department

Process and analytical studies of enhanced low severity co-processing using selective coal pretreatment. Quarterly technical progress report, June--August 1991

Description: This report describes progress on research during the 12th and final quarter of this contract dealing with applications of coal pretreatment techniques in coal/oil co-processing and direct hydroliquefaction. The overall objectives of the project are to investigate various coal pretreatment techniques and to determine the effect of these pretreatment procedures on the reactivity of the coal. Reactivity enhancement will be evaluated under both direct hydroliquefaction and co-processing conditions. Coal conversion utilizing low rank coals and low severity conditions (reaction temperatures generally less than 350{degree}C) is the primary focus of the liquefaction experiments, as it is expected that the effect of pretreatment conditions and the attendant reactivity enhancement will be greatest for these coals and at these conditions.
Date: December 31, 1991
Creator: Baldwin, R. M.; Gaur, S. & Miller, R. L.
Partner: UNT Libraries Government Documents Department

NMR studies of molecules in liquid crystals and graphite

Description: NMR experiments to measure proton dipole couplings were performed on a series of n-alkanes (n-hexane through n-decane) dissolved in nematic liquid crystals. Computer modeling of the experimental NMR-spectra was done using several different models for intermolecular interactions in these systems. The model of Photinos et al. was found to be best in describing the intermolecular interactions in these systems and can provide a statistical picture of the conformation and orientation of the alkane molecules in their partially-oriented environment. Order parameters and conformational distributions for the alkanes can be calculated from the modeling. The alkanes are found to have conformational distributions very much like those found in liquid alkanes. Proton NMR spectra of tetrahydrofuran (THF) intercalated in two graphite intercalation compounds were also measured. Computer simulations of these spectra provide a picture of THF in the constrained environment between the graphene layers where the THF is oriented at a particular angle, can translate and rotate freely, but does not appear to pseudorotate.
Date: June 1, 1992
Creator: Rosen, M. E.
Partner: UNT Libraries Government Documents Department

Synthesis and reactivity of ultra-fine coal liquefaction catalysts

Description: The Pacific Northwest Laboratory is currently developing ultra-fine iron-based coal liquefaction catalysts using two new particle production technologies: (1) modified reverse micelles (MRM) and (2) rapid thermal decomposition of solutes (RTDS). These methodologies have been shown to allow control over both particle size (from 1 nm to 60 nm) and composition when used to produce ultra-fine iron-based materials. Powders produced using these methods are found to be selective catalysts for carbon-carbon bond scission using the naphthyl bibenzylmethane model compound, and to promote the production of THF soluble coal products during liquefaction studies. This report describes the materials produced by both MRM and the RTDS methods and summarizes the results of preliminary catalysis studies using these materials.
Date: October 1, 1992
Creator: Linehan, J. C.; Matson, D. W.; Fulton, J. L.; Bean, R. M. & Darab, J. G.
Partner: UNT Libraries Government Documents Department

NMR studies of the conformation and motion of tetrahydrofuran in graphite intercalation compounds

Description: The behavior of tetrahydrofuran (THF) molecules intercalated in graphite layers in compounds Cs(THF){sub 1.3}C{sub 24} and K(THF){sub 2.5}C{sub 24} was studied by proton NMR. The graphite layers in these compounds impose a uniform ordering on the THF molecules, giving rise to sharp NMR spectra. Experimental and simulated proton NMR spectra were used to investigate geometry, orientation and conformation of intercalated THF, and to determine whether pseudorotation, a large amplitude low-frequency vibration observed in gaseous THF, can also occur in the constrained environment provided by the graphite intercalation compounds. Deuterium and multiple quantum proton NMR spectra were also simulated in order to determine if these techniques could further refine the proton NMR results.
Date: November 1, 1991
Creator: Caplan, D. F.
Partner: UNT Libraries Government Documents Department

Coal liquefaction process streams characterization and evaluation: Application of liquid chromatographic separation methods to THF-soluble portions of integrated two-stage coal liquefaction resids

Description: This study demonstrated the feasibility of using non-aqueous ion exchange liquid chromatography (NIELC) for the examination of the tetrahydrofuran (THF)-soluble distillation resids and THF-soluble whole oils derived from direct coal liquefaction. The technique can be used to separate the material into a number of acid, base, and neutral fractions. Each of the fractions obtained by NIELC was analyzed and then further fractionated by high-performance liquid chromatography (HPLC). The separation and analysis schemes are given in the accompanying report. With this approach, differences can be distinguished among samples obtained from different process streams in the liquefaction plant and among samples obtained at the same sampling location, but produced from different feed coals. HPLC was directly applied to one THF-soluble whole process oil without the NIELC preparation, with limited success. The direct HPLC technique used was directed toward the elution of the acid species into defined classes. The non-retained neutral and basic components of the oil were not analyzable by the direct HPLC method because of solubility limitations. Sample solubility is a major concern in the application of these techniques.
Date: May 1, 1992
Creator: Green, J. B.; Pearson, C. D.; Young, L. L. & Green, J. A.
Partner: UNT Libraries Government Documents Department

Final Technical Report: Effects of Impurities on Fuel Cell Performance and Durability

Description: The main objectives of this project were to investigate the effect of a series of potential impurities on fuel cell operation and on the particular components of the fuel cell MEA, to propose (where possible) mechanism(s) by which these impurities affected fuel cell performance, and to suggest strategies for minimizing these impurity effects. The negative effect on Pt/C was to decrease hydrogen surface coverage and hydrogen activation at fuel cell conditions. The negative effect on Nafion components was to decrease proton conductivity, primarily by replacing/reacting with the protons on the Bronsted acid sites of the Nafion. Even though already well known as fuel cell poisons, the effects of CO and NH3 were studied in great detail early on in the project in order to develop methodology for evaluating poisoning effects in general, to help establish reproducibility of results among a number of laboratories in the U.S. investigating impurity effects, and to help establish lower limit standards for impurities during hydrogen production for fuel cell utilization. New methodologies developed included (1) a means to measure hydrogen surface concentration on the Pt catalyst (HDSAP) before and after exposure to impurities, (2) a way to predict conductivity of a Nafion membranes exposed to impurities using a characteristic acid catalyzed reaction (methanol esterification of acetic acid), and, more importantly, (3) application of the latter technique to predict conductivity on Nafion in the catalyst layer of the MEA. H2-D2 exchange was found to be suitable for predicting hydrogen activation of Pt catalysts. The Nafion (ca. 30 wt%) on the Pt/C catalyst resides primarily on the external surface of the C support where it blocks significant numbers of micropores, but only partially blocks the pore openings of the meso- and macro-pores wherein lie the small Pt particles (crystallites). For this reason, even with 30 wt% Nafion ...
Date: November 11, 2011
Creator: Goodwin, James G., Jr.; Colon-Mercado, Hector; Hongsirikarn, Kitiya & Zhang, Jack Z.
Partner: UNT Libraries Government Documents Department

Divalent Lanthanide Chemistry; Bis(pentamethylcyclopentadienyl)europium(II) and Ytterbium(II) Derivatives: Crystal Structure of Bis(pentamethylcyclopentadienyl) Ytterbium (II)Tetrahydrofuran Hemi (Toluene) at 176K

Description: Red, paramagnetic ({mu}{sub B} = 7.99 B.M., 5-50K) bis(pentamethylcyclopentadienyl) europium (II)(tetrahydrofuran)(diethylether), (Me{sub 5}C{sub 5}){sub 2}Eu(THF)(Et{sub 2}O) is isolated from reaction of three molar equivalents of sodium pentamethylcyclopentadienide and europium trichloride in refluxing tetrahydrofuran, after crystallization from diethyl ether. The monotetrahydrofuran complex, (Me{sub 5}C{sub 5}){sub 2}Eu(THF), may be isolated by use of toluene rather than diethyl ether as the crystallization solvent. Red, diamagnetic bis(pentamethylcyclopentadienyl)ytterbium(II)(tetrahydrofuran) is isolated from the reaction of ytterbium dichloride and sodium pentamethylcyclopentadienide in refluxing tetrahydrofuran. The diethyl ether complex, (Me{sub 5}C{sub 5}){sub 2}Yb(OEt{sub 2}), may be isolated by crystallization of the tetrahydrofuran complex from diethylether, The hemi-toluene complex, (Me{sub 5}C{sub 5}){sub 2} Yb(THF) {center_dot} 1/2 toluene, can be isolated by recrystallization of the tetrahydrofuran complex from toluene. As these divalent metallocenes are the first hydrocarbon-soluble lanthanide derivatives to be isolated we have examined the latter complex by X-ray crystallography. Crystals of (Me{sub 5}C{sub 5}){sub 2}Yb(OC{sub 4}H{sub 8}) {center_dot} 1/2(C{sub 6}H{sub 5}cH{sub 3}) crystalline in the monoclinic system, P2{sub 1}/n, with a = 11.358(8) {angstrom}, b = 21.756(19) {angstrom}, c = 10.691(7) {angstrom}, and {beta} = 101.84(5){sup o} at 176K. For Z = 4 the calculated density is 1.37 g cm{sup -3}. The ytterbium atom is coordinated to the oxygen atom of a tetrahydrofuran molecule and to two pentamethyl cyclopentadienyl rings. The molecule has approximate c{sub 2} symmetry about the Yb-0 bond. The Yb-0 distance is 2.41 {angstrom}, the Yb-C distances average 2.66 {angstrom}, and the Yb-Cp (centroid) distances average 2.37 {angstrom}. The Me{sub 5}C{sub 5} rings are in a staggered configuration with respect to each other. The methyl groups of the Me{sub 5}C{sub 5} groups are displaced by .03 to .21 {angstrom} from the planes of the five-membered rings away from the ytterbium atom. The toluene molecule is not coordinated to the complex and is on a center ...
Date: April 1, 1980
Creator: Tilley, T. Don; Andersen, Richard A.; Spencer, Brock; Ruben, Helena; Zalkin, Allan & Templeton, David H.
Partner: UNT Libraries Government Documents Department