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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

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

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

(Bioprocessing of lignite coals using reductive microorganisms)

Description: The objectives of this report are to: (1) characterize selected aerobic bacterial strains for their abilities to depolymerize lignite coal polymers, and isolate and identify the extracellular enzymes responsible for depolymerization of the coal; (2) characterize selected strictly anaerobic bacteria, that were previously shown to reductively transform coal substructure model compounds, for the ability to similarly transform polymeric coal; and (3) isolate more strains of anaerobic bacteria by enrichment using additional coal substructure model compounds and coal as substrates.
Date: January 1, 1990
Creator: Crawford, D.L.
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

Aliphatic components of coal. Quarterly report, March-June 1980

Description: Liquefaction of coal involves thermolysis of benzyl-oxygen and/or benzyl-benzyl bonds as the first step in the depolymerization. This view derives from NMR studies, studies with model compounds, and oxidative degradations with Na/sub 2/Cr/sub 2/O/sub 7/ and CF/sub 3/CO/sub 3/H/sub 2/. The best method for determining the amount of arylmethyl groups in coals is from the yield of acetic acid formed in oxidative degradation with CF/sub 3/CO/sub 3/H-H/sub 2/SO/sub 4/. The following observations and interpretations are made: a sharp increase in arylmethyl accompanies liquefaction in all five coals and in two coals studied earlier. This increase is the result of thermal cleavage to benzyl radicals and abstraction of hydrogen atoms by the benzyl radicals to form arylmethyl. All five coals give about the same percentage increase in arylmethyl after 90 mins of solvent refining, but not after 3 mins. This indicates that benzyl radicals form from more than one type of structure. Based on studies of model compounds, it is attractive to ascribe arylmethyl formation in 3 mins to cleavage of benzyl ethers and slower cleavage to bibenzyl structures. It might have been expected that the more arylmethyl, the more cleavage, and the more SRC. In fact the opposite is found. The conflict would be resolved if coal liquefaction depended more on certain critical cleavages and the conversion of a 3-dimensional polymer to a 1-dimensional polymer than on the total amount of cleavage and the extent of depolymerization. The amount of arylmethyl in the residue (3 min) is about the same as in the original coal. This indicates that arylmethyls do not play any role in liquefaction as expected. No higher homologs of acetic acid were observed indicating the absence of arylalkyls above methyl.
Date: June 1, 1980
Creator: Deno, N.C.; Cannon, C.; Curry, K.; Jones, A.D.; Potter, T.C.; Rakitsky, W.G. et al.
Partner: UNT Libraries Government Documents Department

Catalytic biomass liquefaction. Quarterly report, January-March 1980

Description: Progress during the quarter in the chemical characterization of the products of wood liquefaction is reported. The liquefaction of hydrolyzed slurries in a tubular reactor bomb system is described. The solvolytic depolymerization of wood is compared to the hydrolysis process. Results of a few illustrative runs are pesented. The characterization and flow properties of concentrated slurries are discussed. Progress on the construction of biomass continuous liquefaction unit is described.
Date: May 1, 1980
Creator: Ergun, S.; Djafar, R.; Figueroa, C.; Karatas, C.; Schaleger, L.; Seth, M. et al.
Partner: UNT Libraries Government Documents Department

Measurement and modeling of advanced coal conversion processes, Volume III

Description: A generalized one-dimensional, heterogeneous, steady-state, fixed-bed model for coal gasification and combustion is presented. The model, FBED-1, is a design and analysis tool that can be used to simulate a variety of gasification, devolatilization, and combustion processes. The model considers separate gas and solid temperatures, axially variable solid and gas flow rates, variable bed void fraction, coal drying, devolatilization based on chemical functional group composition, depolymerization, vaporization and crosslinking, oxidation, and gasification of char, and partial equilibrium in the gas phase.
Date: August 1, 1993
Creator: Ghani, M.U.; Hobbs, M.L. & Hamblen, D.G.
Partner: UNT Libraries Government Documents Department

Novel approaches to a study of the fundamental organic chemistry of coal. Final report, September 1, 1977-September 1, 1979

Description: The studies are preliminary in nature, and the following conclusions are tentative. (1) The results with mixed carboxylic-sulfonic anhydrides seem to indicate an increase in polymerization of the coal molecular structure, when based on the results of pyrolysis/gas chromatographic analyses. The mixed anhydrides are such powerful acylating reagents that they should be capable of causing profound and dramatic structural modifications of coal and the results suggest sub-optimal reaction conditions. The results may also be due to the presence of only a small number of ether linkages connecting large molecular units together. Possibly, at elevated pressures and larger concentrations of mixed anhydride, a greater extent of depolymerization would occur, coupled perhaps with acylation. (2) The Nimz lignin degradation reaction has now been fully implemented and good conditions have been found for lignite reaction. The products from this degradation were basically hydrocarbon in nature. Thus, in the absence of monolignols, we postulate that such phenolic linkages of the type found in lignin are not found to a large degree in Texas lignites. (3) Our recently developed technique of analyzing methylene to methyl ratios by IR spectroscopy represents a useful method for characterization of both soluble and insoluble coal-derived products. The technique is less expensive than mass spectroscopy and not limited by solubility as in the case of NMR spectroscopy. (4) From the measurements of the acidic hydrogen content of the lignites studies, we have formed a postulate as to the involvement of heteroatoms (especially oxygen) in the lignite structure. We feel that heteroatoms in Texas lignites are involved mainly in carbonyl, low molecular weight alkoxy and/or heterocyclic units. (5) Conditions for depolymerizing and solubilizing lignites by use of t-butyllithium have been developed and utilized successfully.
Date: January 1, 1979
Creator: Giam, C.S.; Goodwin, T.E.; Tabor, R.L.; Neff, G.; Smith, S.; Ionescu, F. et al.
Partner: UNT Libraries Government Documents Department

Cooperative research program in coal liquefaction

Description: Research continues on coal liquefaction in the following areas: (1) Iron Based Catalysts for Coal Liquefaction; (2) Exploratory Research on Coal Conversion; (3) Novel Coal Liquefaction Concepts; (4) Novel Catalysts for Coal Liquefaction. (VC)
Date: January 1, 1992
Creator: Huffman, G.P. (ed.)
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

Regulation of coal degradation by fungi. Third quarterly report, January 1995--March 1995

Description: Progress is reported on the solubilization and depolymerization of coal by fungi. It is postulated the the solubilization and depolymerization are separate events. Other objectives include the determination of the role that laccases and peroxidases exert, to access the role of oxygen radicals and oxygen species, and to characterize the solubilization products formed.
Date: April 24, 1995
Creator: Irvine, R.L. & Bumpus, J.A.
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

Studies of the effect of selected nondonor solvents on coal liquefaction yields

Description: The objective of this research program was to evaluate the effectiveness of selected nondonor solvents (i.e., solvents that are not generally considered to have hydrogen available for hydrogenolysis reactions) for the solubilization of coals. Principal criteria for selection of candidate solvents were that the compound should be representative of a major chemical class, should be present in reasonable concentration in coal liquid products, and should have the potential to participate in hydrogen redistribution reactions. Naphthalene, phenanthrene, pyrene, carbazole, phenanthridine, quinoline, 1-naphthol, and diphenyl ether were evaluated to determine their effect on coal liquefaction yields and were compared with phenol and two high-quality process solvents, Wilsonville SRC-I recycle solvent and Lummus ITSL heavy oil solvent. The high conversion efficacy of 1-naphthol may be attributed to its condensation to binaphthol and the consequent availability of hydrogen. The effectiveness of both the nitrogen heterocycles and the polycyclic aromatic hydrocarbon (PAH) compounds may be due to their polycyclic aromatic nature (i.e., possible hydrogen shuttling or transfer agents) and their physical solvent properties. The relative effectiveness for coal conversion of the Lummus ITSL heavy oil solvent as compared with the Wilsonville SRC-I process solvent may be attributed to the much higher concentration of 3-, 4-, and 5-ring PAH and hydroaromatic constituents in Lummus solvent. The chemistry of coal liquefaction and the development of recycle, hydrogen donor, and nondonor solvents are reviewed. The experimental methodology for tubing-bomb tests is outlined, and experimental problem areas are discussed.
Date: September 1, 1983
Creator: Jolley, R. L.; Rodgers, B. R.; Benjamin, B. M.; Poutsma, M. L.; Douglas, E. C. & McWhirter, D. A.
Partner: UNT Libraries Government Documents Department

Engineering Thermotolerant Biocatalysts for Biomass Conversion to Products

Description: Lignocellulosic biomass is a promising feedstock for producing renewable chemicals and transportation fuels as petroleum substitutes. Fermentation of the cellulose in biomass in an SSF process requires that the properties of the microbial biocatalyst match the fungal cellulase activity optima for cost-effective production of products. Fermentation of the pentose sugars derived from hemicellulose in biomass is an additional asset of an ideal biocatalyst. The microbial biocatalyst used by the industry, yeast, lacks the ability to ferment pentose sugars. The optimum temperature for growth and fermentation of yeast is about 35°C. The optimum temperature for commercially available cellulase enzymes for depolymerization of cellulose in biomass to glucose for fermentation is 50-55 °C. Because of the mismatch in the temperature optima for the enzyme and yeast, SSF of cellulose to ethanol (cellulosic ethanol) with yeast is conducted at a temperature that is close to the optimum for yeast. We have shown that by increasing the temperature of SSF to 50-55 °C using thermotolerant B. coagulans, the amount of cellulase required for SSF of cellulose to products can be reduced by 3-4 –fold compared to yeast-based SSF at 35°C with a significant cost savings due to lower enzyme loading. Thermotolerant Bacillus coagulans strains ferment hemicellulose-derived pentose sugars completely to L(+)-lactic acid, the primary product of fermentation. We have developed genetic tools to engineer B. coagulans for fermentation of all the sugars in biomass to ethanol. Using these tools, we have altered the fermentation properties of B. coagulans to produce ethanol as the primary product. The thermotolerant property of B. coagulans has been shown to also lower the cellulase requirement and associated cost in SSF of cellulose to lactic acid compared to lactic acid bacteria. Lactic acid is a potential petroleum substitute for bio-based renewable plastics production. This study has led to the development ...
Date: May 20, 2010
Creator: K. T. Shanmugam, L. O. Ingram and J. A. Maupin-Furlow
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

Analysis of organic sulfur and nitrogen in coal via tandem degradation methods. Technical report, 1 September--30 November 1991

Description: With the recent increase in concern for environmental issues and the implication of sulfur and nitrogen in coal combustion products as prime causes of acid rain, it has become clear that there is an urgent need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. The present study couples mold oxidative and reductive procedures to enhance the depolymerization of coal and its constituent macerals and the quantities of produces amenable to analysis. The study also seeks to apply the degradative techniques to coal asphaltenes, since they are believed to be polymeric structures similar to the whole coal, but smaller and more readily analyzed. While the research effort will focus on Illinois coal, additional samples with even higher sulfur contents will also used, allowing for much easier detection and characterization of organic sulfur structures. A preliminary tests of this hypothesis indicates that many of the same sulfur compounds are present in both the Illinois and in an extremely sulfur-rich coal and that the more complex sulfur compounds are indeed more concentrated in the sulfur-rich sample.
Date: December 31, 1991
Creator: Kruge, M. A.
Partner: UNT Libraries Government Documents Department

Analysis of organic sulfur and nitrogen in coal via tandem degradation methods. Final technical report, 1 September 1991--31 October 1992

Description: With the recent increase in concern for environmental issues and the implication of sulfur and nitrogen in coal combustion preducts as prime causes of acid rain, it has become clear that there is an urgent need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. The principal impediment to the molecular characterization of organic sulfur and nitrogen forms in coal is the polymeric nature of coal`s molecular structure, rendering coal insoluble and impossible to analyze by the necessary gas chromatographic (GC) methods. In our research, we apply mild chemical degradation techniques in order to render coal soluble in common organic solvents and thus amenable to standard GC characterization. The study also seeks to apply the degradative techniques to coal asphaltenes, since they are believed to be polymeric structures similar to the whole coal, but smaller and more readily analyzed. Of the degradation techniques used to date, oxidation by sodium dichromate provides the best chemical structure information. A variety of major sulfur compounds were detected in the dichromate oxidation products of demineralized IBC101 coal, including thiazoles (compounds which contains both sulfur and nitrogen) and a series of isomers of C{sub 2}-, C{sub 3}- and C{sub 4}-alkylthiophene derivatives. Precise agreement between GC-MS and sulfur-selective GC-FPD data was obtained for these compounds, which probably originated as short alkyl chains on exterior portions of the original peat macromolecular structure that were sulfurized shortly after burial by H{sub 2}S. The results were further confirmed by the analysis of a non-Illinois Basin coal with nearly twice the organic sulfur content of IBC101.
Date: December 31, 1992
Creator: Kruge, M. A. & Palmer, S. R.
Partner: UNT Libraries Government Documents Department

Analysis of organic sulfur and nitrogen in coal via tandem degradation methods

Description: With the recent increase in concern for environmental issues and the implication of sulfur and nitrogen in coal combustion products as prime causes of acid rain, it has become clear that there is an urgent need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. The present study couples mold oxidative and reductive procedures to enhance the depolymerization of coal and its constituent macerals and the quantities of produces amenable to analysis. The study also seeks to apply the degradative techniques to coal asphaltenes, since they are believed to be polymeric structures similar to the whole coal, but smaller and more readily analyzed. While the research effort will focus on Illinois coal, additional samples with even higher sulfur contents will also used, allowing for much easier detection and characterization of organic sulfur structures. A preliminary tests of this hypothesis indicates that many of the same sulfur compounds are present in both the Illinois and in an extremely sulfur-rich coal and that the more complex sulfur compounds are indeed more concentrated in the sulfur-rich sample.
Date: January 1, 1991
Creator: Kruge, M.A.
Partner: UNT Libraries Government Documents Department

Lignin-assisted coal depolymerization. Technical report, September 1, 1991--November 30, 1991

Description: Previous research has shown that addition of lignin-derived liquids to coal stirred in tetralin under mild reaction conditions (375{degree}C and 300--500 psig) results in a marked enhancement in the rate of coal depolymerization. A mathematical model was developed to study the kinetics of coal depolymerization in the presence of liquid-derived liquids. In the present study, a reaction pathway was formulated to explain the enhancement in coal depolymerization due to lignin (solid) addition. The model postulated assumes that the products of lignin obtained during thermolysis interact with the reactive moieties present in coal while simultaneous depolymerization of coal occurs. A good fit between the experimental data and the kinetic model was found. The results show that in addition to the enhancement in the rate of coal depolymerization, lignin also reacts (and enhances the extent of depolymerization of coal) with those reaction sites in coal that are not susceptible to depolymerization when coal alone is reacted in tetralin under identical reaction conditions. Additional work is being carried out to determine a thorough materials balance on the lignin-assisted coal depolymerization process. A number of liquid samples have been obtained which are being studied for their stability in various environments. 5 refs., 4 figs., 1 tab.
Date: December 31, 1991
Creator: Lalvani, S. B.
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

Lignin-assisted coal depolymerization

Description: Previous research has shown that addition of lignin-derived liquids to coal stirred in tetralin under mild reaction conditions (375{degree}C and 300--500 psig) results in a marked enhancement in the rate of coal depolymerization. A mathematical model was developed to study the kinetics of coal depolymerization in the presence of liquid-derived liquids. In the present study, a reaction pathway was formulated to explain the enhancement in coal depolymerization due to lignin (solid) addition. The model postulated assumes that the products of lignin obtained during thermolysis interact with the reactive moieties present in coal while simultaneous depolymerization of coal occurs. A good fit between the experimental data and the kinetic model was found. The results show that in addition to the enhancement in the rate of coal depolymerization, lignin also reacts (and enhances the extent of depolymerization of coal) with those reaction sites in coal that are not susceptible to depolymerization when coal alone is reacted in tetralin under identical reaction conditions. Additional work is being carried out to determine a thorough materials balance on the lignin-assisted coal depolymerization process. A number of liquid samples have been obtained which are being studied for their stability in various environments. 5 refs., 4 figs., 1 tab.
Date: January 1, 1991
Creator: Lalvani, S.B.
Partner: UNT Libraries Government Documents Department