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Sixteenth Quarterly Report Regulation of Coal Polymer Degradation by Fungi

Description: Three phenomena which concern coal solubilization and depolymerization were studied during this reporting period. Previous investigations have shown that lignin peroxidases mediate the oxidation of soluble coal macromolecule. Because it appears to be a substrate, soluble coal macromolecule is also an inhibitor of veratryl alcohol oxidation, a reaction that is mediated by these enzymes. The mechanism of inhibition is complex in that oxidation (as assayed by decolorization) of soluble coal macromolecule requires the presence of veratryl alcohol and veratryl alcohol oxidation occurs only after a substantial lag period during which the soluble coal macromolecule is oxidized. In a previous quarterly report we proposed a reaction mechanism by which this may occur. During the present reporting period we showed that our proposed reaction mechanism is consistent with classical enzyme kinetic theory describing enzyme activity in the presence of a potent inhibitor (i.e., an inhibitor with a very low KI ). The oxidative decolorization and depolymerization of soluble coal macromolecule was also studied. Because wood rotting fungi produce hydrogen peroxide via a variety of reactions, we studied the effect of hydrogen peroxide on soluble coal macromolecule decolorization and depolymerization. Results showed that substantial decolorization occurred only at hydrogen peroxide concentrations that are clearly non-physiological (i.e., 50 mM or greater). It was noted, however, that when grown on solid lignocellulosic substrates, wood rotting fungi, overtime, cumulatively could produce amounts of hydrogen peroxide that might cause significant oxidative degradation of soluble coal macromolecule. Thirdly, we have shown that during oxalate mediated solubilization of low rank coal, a pH increase is observed. During this reporting period we have shown that the pH of solutions containing only sodium oxalate also undergo an increase in pH, but to a lesser extent than that observed in mixtures containing sodium oxalate and low rank coal. It is our hypothesis ...
Date: July 31, 1998
Creator: Bumpus, John A.
Partner: UNT Libraries Government Documents Department

Nylon Dissolution in Nitric Acid Solutions

Description: H Area Operations is planning to process Pu-contaminated uranium scrap in support of de-inventory efforts. Nylon bags will be used to hold materials to be dissolved in H-Canyon. Based on this set of twelve nylon dissolutions, it is concluded that (when other variables are held constant): increased acid concentration results in increased dissolution rates; increased acid concentration results in a lower dissolution onset temperature; little, if any, H plus is consumed during the depolymerization process; and 2.0-3.0 M HNO3, with 0.025 M KF and 2 g/L B, is satisfactory for the dissolution of nylon bag materials to be used during H-Canyon processing.
Date: June 16, 2004
Creator: KESSINGER, GLENF.
Partner: UNT Libraries Government Documents Department

Bacterial quorum sensing and nitrogen cycling in rhizosphere soil

Description: Plant photosynthate fuels carbon-limited microbial growth and activity, resulting in increased rhizosphere nitrogen (N)-mineralization. Most soil organic N is macromolecular (chitin, protein, nucleotides); enzymatic depolymerization is likely rate-limiting for plant N accumulation. Analyzing Avena (wild oat) planted in microcosms containing sieved field soil, we observed increased rhizosphere chitinase and protease specific activities, bacterial cell densities, and dissolved organic nitrogen (DON) compared to bulk soil. Low-molecular weight DON (<3000 Da) was undetectable in bulk soil but comprised 15% of rhizosphere DON. Extracellular enzyme production in many bacteria requires quorum sensing (QS), cell-density dependent group behavior. Because proteobacteria are considered major rhizosphere colonizers, we assayed the proteobacterial QS signals acyl-homoserine lactones (AHLs), which were significantly increased in the rhizosphere. To investigate the linkage between soil signaling and N cycling, we characterized 533 bacterial isolates from Avena rhizosphere: 24% had chitinase or protease activity and AHL production; disruption of QS in 7 of 8 eight isolates disrupted enzyme activity. Many {alpha}-Proteobacteria were newly found with QS-controlled extracellular enzyme activity. Enhanced specific activities of N-cycling enzymes accompanied by bacterial density-dependent behaviors in rhizosphere soil gives rise to the hypothesis that QS could be a control point in the complex process of rhizosphere N-mineralization.
Date: October 1, 2008
Creator: DeAngelis, K. M.; Lindow, S. E. & Firestone, M. K.
Partner: UNT Libraries Government Documents Department

Degradation kinetics of polymers in solution: Time-dependence of molecular weight distributions. [Quarterly report, January--March 1996]

Description: Polymer degradation occurs when polymer chains are broken under the influence of thermal, mechanical, or chemical energy. Chain-end depolymerization and random- and midpoint-chain scission are mechanisms that have been observed in liquid-phase polymer degradation. Here we develop mathematical models, unified by continuous-mixture kinetics, to show how these different mechanisms affect polymer degradation in solution. Rate expressions for the fragmentation of molecular-weight distributions (MWDs) govern the evolution of the MWDs. The governing integro-differential equations can be solved analytically for realistic conditions. Moment analysis for first-order continuous kinetics shows the temporal behavior of MWDs. Chain-end depolymerization yields monomer product and polymer molecular-weight moments that vary linearly with time. In contrast, random- and midpoint-chain scission models display exponential time behavior. The mathematical results reasonably portray experimental observations for polymer degradation. This approach, based on the time evolution of continuous distributions of chain length or molecular weight, provides a framework for interpreting several types of polymer degradation processes.
Date: February 27, 1996
Creator: McCoy, B.J. & Madras, G.
Partner: UNT Libraries Government Documents Department

Pyrolysis mechanisms of lignin model compounds

Description: The flash vacuum pyrolysis of lignin model compounds was studied under conditions optimized for the production of liquid products to provide mechanistic insight into the reaction pathways that lead to product formation. The major reaction products can be explained by cleavage of the C-O either linkage by a free radial or concerted 1,2-elimination.
Date: June 1, 1997
Creator: Britt, P.F.; Buchanan, A.C. III & Cooney, M.J.
Partner: UNT Libraries Government Documents Department

Preparation of hollow shell ICF targets using a depolymerizing model

Description: A new technique for producing hollow shell laser fusion capsules was developed that starts with a depolymerizable mandrel. In this technique we use poly(alpha-methylstyrene) (PAMS) beads or shells as mandrels which are overcoated with plasma polymer. The PAMS mandrel is thermally depolymerized to gas phase monomer, which diffuses through the permeable and thermally more stable plasma polymer coating, leaving a hollow shell. We have developed methods for controlling the size of the PAMS mandrel by either grinding to make smaller sizes or melt sintering to form larger mandrels. Sphericity and surface finish are improved by heating the PAMS mandrels in hot water using a surfactant to prevent aggregation. Using this technique we have made shells from 200 {mu}m to 5 mm diameter with 15 to 100 {mu}m wall thickness having sphericity better than 2 {mu}m and surface finish better than 10 nm RMS.
Date: November 1, 1994
Creator: Letts, S.A.; Fearon, E.M. & Buckley, S.R.
Partner: UNT Libraries Government Documents Department

Energy and environmental (JSR) research emphasizing low-rank coal

Description: The products of plastic thermal depolymerization can be used for the manufacture of new plastics or various other hydrocarbon-based products. One thermal depolymerization development effort is ongoing at the Energy & Environmental Research Center (EERC) of the University of North Dakota, under joint sponsorship of the American Plastics Council, the 3M corporation, and the Department of Energy. Thermal depolymerization process development began at the EERC with a benchscale program that ran from 9/92 to 6/93 (1). Testing was conducted in a 1-4-lb/hr continuous fluid-bed reactor (CFBR) unit using individual virgin resins and resin blends and was intended to determine rough operating parameters and product yields and to identify product stream components. Process variables examined included temperature and bed material, with a lesser emphasis on gas fluidization velocity and feed material mix. The following work was performed: (1) a short program to determine the suitability of using CaO in a postreactor, fixed bed for chlorine remediation, (2) thermal depolymerization of postconsumer plastics, and (3) testing of industrial (3M) products and wastes to determine their suitability as feed to a thermal depolymerization process. The involvement of DOE in the development of the plastics thermal depolymerization process has helped to facilitate the transfer of coal conversion technology to a new and growing technology area -- waste conversion. These two technology areas are complementary. The application of known coal conversion technology has accelerated the development of plastics conversion technology, and findings from the plastics depolymerization process development, such as the development of chlorine remediation techniques and procedures for measurement of organically associated chlorine, can be applied to new generations of coal conversion processes.
Date: December 1, 1994
Creator: Sharp, L.L.
Partner: UNT Libraries Government Documents Department

Large scale solubilization of coal and bioconversion to utilizable energy. Quarterly technical progress report, January-March 1994

Description: In order to develop a system for large scale coal solubilization and its bioconversion to utilizable fuel, the authors plan to clone the genes encoding Neurospora protein that facilitate depolymerization of coal. They also plan to use desulfurizing bacteria to remove the sulfur in situ and use other microorganisms to convert biosolubilized coal into utilizable energy following an approach utilizing several microorganisms (Faison). In addition the product of coal solubilized by fungus will be characterized to determine their chemical nature and the mechanism of reaction catalyzed by fungal product during in vivo and in vitro solubilization by the fungus or purified fungal protein.
Date: June 1, 1994
Creator: Mishra, N. C.
Partner: UNT Libraries Government Documents Department

Studies of coupled chemical and catalytic coal conversion methods. Eleventh quarterly report, April--June 1990

Description: The objective of our work is coal liquefaction under relatively mild conditions. Our attempts were to depolymerize the coal macromolecule to smaller fragments which could be more easily solubilized in conventional organic solvents. During the last few months we have been working on nonreductive C-alkylation procedures. The effectiveness of the newly introduced alkyl groups for the disruption of intemolecular hydrogen bonds and pi-pi interactions between the aromatic sheets in the coal mdcromolecule had been recognized. During the present quarter, a new approach for the depolymerization of the coal macromolecule was tried. This was aimed towards carbon-carbon bond cleavage in the presence of strong bases. Such bond cleavage reactions are well known with the alkali metals. Electron transfer reactions take place from the metals to the aromatic nuclei resulting in the formation of anion radicals (or dianions) which subsequently undergo carbon-carbon bond cleavage. In our work, instead of using the alkali metals, we have used bases to cleave the carbon-carbon bonds by base catalyzed hydrocarbon elimination reactions.Such anionic fragmentation reactions involving strong bases are not very well established. The only discrete evidence of carbon-carbon bond cleavage with bases were obtained from some earlier works of Grovenstein.
Date: December 31, 1990
Creator: Stock, L. M.
Partner: UNT Libraries Government Documents Department

Novel process for depolymerization of coal to C{sub 2}--C{sub 4} hydrocarbons. Progress report No. 13, September 1--November 30, 1992

Description: An envelope of parameter values has been experimentally identified in our laboratory, heretofore unexplored, for the catalytic depolymerization of coal which leads to yields of C{sub 2}-C{sub 4} hydrocarbons in excess of 50 weight percent of the coal, in a direct, single-stage process under mild conditions. The chemistry observed is fundamentally different from all coal conversion processes, both liquefaction and gasification, previously reported in the literature. The process-derived recycle liquid solvent will be characterized, and is expected to constitute a super-critical phase under conditions of temperature and pressure imposed by the chemistry of the system. Using a special reactor incorporating windows for visual observation, the operation of a catalyst bed fluidized by super-critical, coal-derived fluids will be examined. The capability of such a supercritical, coal-derived fluid to control agglomeration of a strongly caking coal, in the catalyst bed, will be evaluated, and satisfactory control developed. Solvent upgrading of the recycled liquids will be applied as may be required.
Date: December 1, 1992
Creator: Wiser, W. H. & Oblad, A. G.
Partner: UNT Libraries Government Documents Department

Batch Microreactor Studies of Lignin Depolymerization by Bases. 2. Aqueous Solvents

Description: Biomass feedstocks contain roughly 15-30% lignin, a substance that can not be converted to fermentable sugars. Hence, most schemes for producing biofuels assume that the lignin coproduct will be utilized as boiler fuel. Yet, the chemical structure of lignin suggests that it will make an excellent high value fuel additive, if it can be broken down into smaller compounds. From Fiscal year 1997 through Fiscal year 2001, Sandia National Laboratories participated in a cooperative effort with the National Renewable Energy Laboratory and the University of Utah to develop and scale a base catalyzed depolymerization (BCD) process for lignin conversion. SNL's primary role in the effort was to perform kinetic studies, examine the reaction chemistry, and to develop alternate BCD catalyst systems. This report summarizes the work performed at Sandia during Fiscal Year 1999 through Fiscal Year 2001 with aqueous systems. Work with alcohol based systems is summarized in part 1 of this report. Our study of lignin depolymerization by aqueous NaOH showed that the primary factor governing the extent of lignin conversion is the NaOH:lignin ratio. NaOH concentration is at best a secondary issue. The maximum lignin conversion is achieved at NaOH:lignin mole ratios of 1.5-2. This is consistent with acidic compounds in the depolymerized lignin neutralizing the base catalyst. The addition of CaO to NaOH improves the reaction kinetics, but not the degree of lignin conversion. The combination of Na{sub 2}CO{sub 3} and CaO offers a cost saving alternative to NaOH that performs identically to NaOH on a per Na basis. A process where CaO is regenerated from CaCO{sub 3} could offer further advantages, as could recovering the Na as Na{sub 2}CO{sub 3} or NaHCO{sub 3} by neutralization of the product solution with CO2. Model compound studies show that two types of reactions involving methoxy substituents on the aromatic ...
Date: May 1, 2002
Creator: MILLER, JAMES E.; EVANS, LINDSEY; MUDD, JASON E. & BROWN, KARA A.
Partner: UNT Libraries Government Documents Department

FUNDAMENTAL KINETICS OF SUPERCRITICAL COAL LIQUEFACTION: EFFECT OF CATALYSTS AND HYDROGEN-DONOR SOLVENTS

Description: This report outlines a distribution kinetics approach to macromolecular reactions that has been applied to several processes. The objective was to develop an understanding of high-temperature, dense-phase thermolytic processes for complex macromolecular systems, such as coal. Experiments and theory are described for chemical models that simulate depolymerization of coal. The approach has been exceptionally successful for the model macromolecular systems. Development of a novel chemical reaction engineering analysis, based on distribution kinetics, was a major accomplishment of the current research.
Date: August 1, 1998
Creator: McCoy, Benjamin J. & Smith, J.M.
Partner: UNT Libraries Government Documents Department

Large scale solubilization of coal and bioconversion to utilizable energy. Seventh quarterly technical progress report, April 1, 1995--June 30, 1995

Description: In order to develop a system for a large scale coal solubilization and its bioconversion to utilizable fuel, we plan to clone the genes encoding Neurospora protein that facilitate depolymerization of coal. We also plan to use desulfurizing bacteria to remove the sulfur in situ and use other microorganisms to convert biosolubilized coal into utilizable energy following an approach utilizing several microorganisms. In addition the product of coal solubilized by fungus will be characterized to determine their chemical nature and the mechanism of reaction catalyzed by fungal product during in vivo and in vitro solubilization by the fungus or purified fungal protein.
Date: December 1, 1995
Creator: Mishra, N.C.
Partner: UNT Libraries Government Documents Department

Batch Microreactor Studies of Lignin Depolymerization by Bases. 1. Alcohol Solvents

Description: Biomass feedstocks contain roughly 10-30% lignin, a substance that can not be converted to fermentable sugars. Hence, most schemes for producing biofuels (ethanol) assume that the lignin coproduct will be utilized as boiler fuel to provide heat and power to the process. However, the chemical structure of lignin suggests that it will make an excellent high value fuel additive, if it can be broken down into smaller molecular units. From fiscal year 1997 through fiscal year 2001, Sandia National Laboratories was a participant in a cooperative effort with the National Renewable Energy Laboratory and the University of Utah to develop and scale a base catalyzed depolymerization (BCD) process for lignin conversion. SNL's primary role in the effort was to utilize rapidly heated batch microreactors to perform kinetic studies, examine the reaction chemistry, and to develop alternate catalyst systems for the BCD process. This report summarizes the work performed at Sandia during FY97 and FY98 with alcohol based systems. More recent work with aqueous based systems will be summarized in a second report.
Date: May 1, 2002
Creator: MILLER, JAMES E.; EVANS, LINDSEY; LITTLEWOLF, ALICIA & TRUDELL, DANIEL E.
Partner: UNT Libraries Government Documents Department

Lignin-assisted coal depolymerization. [Final] technical report, September 1, 1991--August 31, 1992

Description: Liquefaction of an Illinois bituminous and a caustic lignin was studied in an initial hydrogen pressure of 140 psig. Experiments were conducted in the temperature range of 325-375{degree}C in tetralin. The addition of lignin to coal was found to be synergistic in that it significantly improves the quality and yield of the liquid products obtained. Kinetic data for coal conversion enhancement due to lignin addition were obtained. A mathematical model describing the reaction chemistry, using lignin, has been proposed and developed. The analysis of the results indicates that the intermediates produced from lignin were responsible for enhancement in coal depolymerization rate, however, the intermediates are short-lived as compared to the time needed for a significant coal conversion yield. Coal depolymerization rate was found to be a function of time; compared to processing coal alone, it doubled upon reacting coal with lignin at 375{degree}C and after 67 minutes from the beginning of the experiment. Overall mass recoveries of 95--98% of the total mass charged to the reactor were obtained. A careful statistical analysis of the data shows that coal depolymerization yield is enhanced by 11.9% due to the lignin addition. The liquids obtained were examined for their elemental composition, and molecular weight determination by size exclusion chromatography. The stability of liquid products was characterized by determining their solubility in pentane and benzene, and by evaluating the molecular weight.
Date: December 31, 1992
Creator: Lalvani, S. B.; Muchmore, C. B.; Koropchak, J. A. & Kim, Jong Won
Partner: UNT Libraries Government Documents Department

Studies of coupled chemical and catalytic coal conversion methods. Twelfth quarterly report, July--September 1990

Description: During the previous quarter, a new approach for the deploymerization of the coal macromolecule was tried. This was aimed towards carbon-carbon bond cleavage in presence of strong bases. Such bond cleavage reactions are well known with the alkali metals. Electron transfer reactions take place from the metals to the aromatic nuclei resulting in the formation ofanion-radicals (or dianions) which subsequently undergo carbon-carbon bond cleavage. In our work instead of using the alkali metals, we have used strong bases to cleave the carbon-carbon bonds in hydrocarbons, and have suggested that hydrocarbon elimination reactions occur. Such anionic fragmentation reactions involving strong bases are not very well established. However, we have obtained circumstantial evidence that such bond cleavage reactions do take place in some coal systems. For example, when the high rank Lower Kittaming coal, PSOC 1197, was treated with Lochmann`s base (equimolar mixture of n-butyllithiun and potassium tert-butoxide) in refluxing heptane and quenched with ammonium chloride and reethanol, the pyridine solubility of the product increased from 5% (raw coal) to 39%. A similar increase in solubility due to base treatment was also observed in a separate study for another high rank coal, Pocahontas No. 3 from the Argonne National Laboratory Premium Sample Program. The solubility of the coal increased frcm 5% to 32% after the base treatment. These results, together with the absence of literature studies on base promoted fragmentation reactions prompted us to perfom reactions on some pure compounds to assess this concept in more detail.
Date: December 31, 1990
Creator: Stock, L. M.
Partner: UNT Libraries Government Documents Department

Lignin-assisted coal depolymerization. Technical report, December 1, 1991--February 29, 1992

Description: Previous research has shown that addition of lignin and lignin-derived liquids to coal stirred in tetralin under mild reaction conditions (375{degrees}C and 300--500 psig) results in a marked enhancement in the rate of coal depolymerization. In this quarterly report, overall mass balances on experiments conducted with tetralin, coal, lignin and coal-lignin mixture are reported. Overall mass recoveries of 95--99% of the total mass charged to the reactor were obtained. A number of experiments were conducted on coal, lignin and coal-lignin depolymerization. A careful statistical analysis of the data shows that coal depolymerization is enhanced by 10.4%, due to the lignin addition. The liquids obtained are being examined for their elemental composition, and molecular weight determination by size exclusion chromatography. The stability of the liquid products is being examined in various environments. The gaseous product analyses show that the major gases produced during the course of depolymerization are CO, CH{sub 4}, and CO{sub 2}. When coal and lignin are reacted together, the amount of CO and CH{sub 4}produced respectively 12% and 38% greater than the corresponding amount of gases calculated, based on the weighted average of values obtained for coal and lignin alone. The data obtained show that lignin addition to coal is synergistic in that not only is the extent of coal depolymerization increased, but the gas produced contains higher concentrations of more desirable gaseous products.
Date: August 1, 1992
Creator: Lalvani, S. B.
Partner: UNT Libraries Government Documents Department

Sequential low-temperature depolymerization and liquefaction of US coals. Progress report No. 5, October 1--December 31, 1987

Description: A Beulah-Zap (North Dakota) lignite sample, designated below as BZ(ND) lignite, was obtained from the Argonne National Laboratory premium coal program. This lignite had the following ultimate analysis (MAF basis) in wt.%: C, 71.05; H, 5.58; N, 1.17; S, 1.60; 0 (diff), 20.6. The ash content (dry basis) was 6.0 wt.%. As expected, the BZ(ND) lignite had a considerably higher oxygen content ({approximately}20.6%) in comparison with that of previously studied coals (Progress Reports nos. 1--4). The BZ(ND) lignite was subjected to a previously developed stepwise depolymerization-liquefaction procedure [for details and recent applications see J. Shabtai and T. Skulthai, Proc. 1987 Internat. Confer. Coal Science, Elsevier, Amsterdam (J.A. Moulijn, K.A. Nater, and H.A.G. Chermin, Eds.), 1987, pp. 761764; and J. Shabtai, T. Skulthai, and I. Saito, Am. Chem. Soc. Div. Fuel Chem. Prepr., 31 (4), 15--23 (1986)]. The procedure, as summarized in Figure 1, consists essentially of the following sequential steps: (1) intercalation of the coal sample with catalytic amounts (5--20 %) of FeCl{sub 3} followed by mild hydrotreatment (HT) of the coal-FeCl{sub 3} intercalate; (2) base-catalyzed depolymerization (BCD) of the product from step 1, under super-critical conditions; and (3) hydroprocessing (HPR) of the depolymerized product from the two preceding steps, using a sulfided 6Co8Mo catalyst. The results obtained in processing the BZ(ND) lignite according to the above procedure are described.
Date: March 1, 1988
Creator: Shabtai, J. S. & Wiser, W. H.
Partner: UNT Libraries Government Documents Department

Regulation of coal polymer degradation by fungi. Fourth quarterly progress report, May 1995--June 1995

Description: To test the hypothesis that coal (leonardite) Solubilization and the subsequent depolymerization of the solubilized coal macromolecules are distinct events in lignin degrading fungi. In addition to T versicolor, Phanerochaete chrysosporium, another lignin degrading fungus that also has the ability to solubilize coal, will be studied. To test the hypothesis that the processes of coal (leonardite) solubilization and coal macro molecule depolymerization in lignin degrading fungi can be regulated by altering the nutritional status of the microorganism. Coal solubilization is expected to occur in nutrient rich media whereas depolymerization of solubilized coal macromolecules is expected to occur in nutrient limited media. To determine the role of extracellular enzymes (laccases, lignin peroxidases and Mn peroxidases) that are secreted by lignin degrading fungi during coal solubilization or coal macro molecule depolymerization. To assess the role of enzymatically generated oxygen radicals, non-radical active oxygen species, veratryl alcohol radicals and Mn{sup +++} complexes in coal macro molecule depolymerization. To characterize products of coal solubilization and coal macro molecule depolymerization that are formed by T. versicolor and P. chrysosporium and their respective extracellular enzymes. Solubilization products formed using oxalic acid and other metal chelators will also be characterized and compared.
Date: July 24, 1995
Creator: Irvine, R.L.
Partner: UNT Libraries Government Documents Department

Large scale solubilization of coal and bioconversion to utilizable energy. Eighth quarterly technical progress report, July 1, 1995--September 30, 1995

Description: In order to develop a system for a large scale coal solubilization and its bioconversion to utilizable fuel, we plan to clone the genes encoding Neurospora protein that facilitate depolymerization of coal. We also plan to use desulfurizing bacteria to remove the sulfur in situ and use other microorganisms to convert biosolubilized coal into utilizable energy following an approach utilizing several microorganisms. In addition the product of coal solubilized by fungus will be characterized to determine their chemical nature and the mechanism of reaction catalyzed by fungal product during in vivo and in vitro solubilization by the fungus or purified fungal protein.
Date: February 1, 1996
Creator: Mishra, N.C.
Partner: UNT Libraries Government Documents Department

Technical Basis for Safe Operations with Pu-239 in NMS and S Facilities (F and H Areas)

Description: Plutonium-239 is now being processed in HB-Line and H-Canyon as well as FB-Line and F-Canyon. As part of the effort to upgrade the Authorization Basis for H Area facilities relative to nuclear criticality, a literature review of Pu polymer characteristics was conducted to establish a more quantitative vs. qualitative technical basis for safe operations. The results are also applicable to processing in F Area facilities.The chemistry of Pu polymer formation, precipitation, and depolymerization is complex. Establishing limits on acid concentrations of solutions or changing the valence to Pu(III) or Pu(VI) can prevent plutonium polymer formation in tanks in the B lines and canyons. For Pu(IV) solutions of 7 g/L or less, 0.22 M HNO3 prevents polymer formation at ambient temperature. This concentration should remain the minimum acid limit for the canyons and B lines when processing Pu-239 solutions. If the minimum acid concentration is compromised, the solution may need to be sampled and tested for the presence of polymer. If polymer is not detected, processing may proceed. If polymer is detected, adding HNO3 to a final concentration above 4 M is the safest method for handling the solution. The solution could also be heated to speed up the depolymerization process. Heating with > 4 M HNO3 will depolymerize the solution for further processing.Adsorption of Pu(IV) polymer onto the steel walls of canyon and B line tanks is likely to be 11 mg/cm2, a literature value for unpolished steel. This value will be confirmed by experimental work. Tank-to-tank transfers via steam jets are not expected to produce Pu(IV) polymer unless a larger than normal dilution occurs (e.g., >3 percent) at acidities below 0.4 M.
Date: March 18, 1999
Creator: Bronikowski, M.G.
Partner: UNT Libraries Government Documents Department

Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Final report

Description: Development of new catalysts is a promising approach to more efficient coal liquefaction. It has been recognized that dispersed catalysts are superior to supported catalysts for primary liquefaction of coals, because the control of initial coal dissolution or depolymerization requires intimate contact between the catalyst and coal. This research is a fundamental and exploratory study on catalytic coal liquefaction, with the emphasis on exploring novel bimetallic dispersed catalysts for coal liquefaction and the effectiveness of temperature-programmed liquefaction using dispersed catalysts. The primary objective of this research was to explore novel bimetallic dispersed catalysts from organometallic molecular precursors, that could be used in low concentrations but exhibit relatively high activity for efficient hydroliquefaction of coals under temperature-programmed conditions. We have synthesized and tested various catalyst precursors in liquefaction of subbituminous and bituminous coals and in model compound studies to examine how do the composition and structure of the catalytic precursors affect their effectiveness for coal liquefaction under different reaction conditions, and how do these factors affect their catalytic functions for hydrogenation of polyaromatic hydrocarbons, for cleavage of C-C bonds in polycyclic systems such as 4-(1-naphthylmethyl)bibenzyl, for hydrogenolysis of C-O bond such as that in dinaphthylether, for hydrodeoxygenation of phenolic compounds and other oxygen-containing compounds such as xanthene, and for hydrodesulfurization of polycyclic sulfur compounds such as dibenzothiophene. The novel bimetallic and monometallic precursors synthesized and tested in this project include various Mo- and Fe-based compounds.
Date: November 1, 1997
Creator: Song, Chunshan; Schobert, H.H. & Parfitt, D.P.
Partner: UNT Libraries Government Documents Department

LDRD final report on intelligent polymers for nanodevice performance control

Description: A variety of organic and hybrid organic-inorganic polymer systems were prepared and evaluated for their bulk response to optical, thermal and chemical environmental changes. These included modeling studies of polyene-bridged metal porphyrin systems, metal-mediated oligomerization of phosphaalkynes as heteroatomic analogues to polyacetylene monomers, investigations of chemically amplified degradation of acid- and base-sensitive polymers and thermally responsive thermoplastic thermosets based on Diels-Alder cycloaddition chemistry. The latter class of materials was utilized to initiate work to develop a new technique for rapidly building a library of systems with varying depolymerization temperatures.
Date: January 1, 2000
Creator: JAMISON,GREGORY M.; LOY,DOUGLAS A.; WHEELER,DAVID R.; SAUNDERS,RANDALL S.L; SHELNUTT,JOHN A.; CARR,MARTIN J. et al.
Partner: UNT Libraries Government Documents Department