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SULFUR REDUCTION IN GASOLINE AND DIESEL FUELS BY EXTRACTION/ADSORPTION OF REFRACTORY DIBENZOTHIOPHENES

Description: Refractory 4,6-dimethyldibenzothiophene, which is difficult to remove from petroleum feedstocks, binds to the Ru in Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+} by displacing the H{sub 2}O ligand. Thiophene, benzothiophene and dibenzothiophene (DBT) also react with Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+} similarly. This binding ability of Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+} has been used to remove over 50% of the DBT in simulated petroleum feedstocks by a biphasic extraction process. The extraction phase is readily regenerated by air-oxidation thereby completing a cyclic process that removes DBT from petroleum feedstocks. Solid phase extractants consisting of Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+}, CpRu(CO){sub 2}(BF{sub 4}), CpFe(CO){sub 2}(C{sub 4}H{sub 8}){sup +} and AgX (where X = BF{sub 4}{sup -}, PF{sub 6}{sup -} or NO{sub 3}{sup -}) adsorbed on silica have also been used to remove DBT and 4,6-Me{sub 2}DBT from simulated petroleum feedstocks. The AgX/silica adsorbents remove 90% of the DBT and 4,6-Me{sub 2}DBT and can be regenerated and re-used for multiple extractions, which makes these adsorbents of potential industrial use for the removal of refractory dibenzothiophenes from petroleum feedstocks.
Date: June 1, 2003
Creator: Angelici, Robert J.
Partner: UNT Libraries Government Documents Department

Transition Metal Complexes of Cr, Mo, W and Mn Containing {eta}{sup 1}(S)-2,5-Dimethylthiophene, Benzothiophene and Dibenzothiophene Ligands

Description: The UV photolysis of hexanes solutions containing the complexes M(CO){sub 6} (M=Cr, Mo, W) or CpMn(CO){sub 3} (Cp={eta}{sup 5}-C{sub 5}H{sub 5}) and excess thiophene (T{sup *}) (T{sup *}=2,5-dimethylthiophene (2,5-Me{sub 2}T), benzothiophene (BT), and dibenzothiophene (DBT)) produces the {eta}{sup 1}(S)-T{sup *} complexes (CO){sub 5}M({eta}{sup 1}(S)-T{sup *}) 1-8 or Cp(CO){sub 2}Mn({eta}{sup 1}(S)-T{sup *})9-11, respectively. However, when T{sup *}=DBT, and M=Mo, a mixture of two products result which includes the {eta}{sup 1}(S)-DBT complex (CO){sub 5}Mo({eta}{sup 1}(S)-DBT) 4a and the unexpected {pi}-complex (CO){sub 3}Mo({eta}{sup 6}-DBT) 4b as detected by {sup 1}H NMR. The liability of the {eta}{sup 1}(S)-T{sup *} ligands is illustrated by the rapid displacement of DBT in the complex (CO){sub 5}W({eta}{sup 1}(S)-DBT) (1) by THF, and also in the complexes (CO){sub 5}Cr({eta}{sup 1}(S)-DBT) (5) and CpMn(CO){sub 2}({eta}{sup 1}(S)-DBT) (9) by CO (1 atm) at room temperature. Complexes 1-11 have been characterized spectroscopically ({sup 1}H NMR, IR) and when possible isolated as analytically pure solids (elemental analysis, EIMS). Single crystal, X-ray structural determinations are reported for (CO){sub 5}W({eta}{sup 1}(S)-DBT) and Cp(CO){sub 2}Mn({eta}{sup 1}(S)-DBT).
Date: September 21, 2000
Creator: Reynolds, M.
Partner: UNT Libraries Government Documents Department

Synthesis of 6-Methyl-9-n-propyldibenzothiophene-4-ol. Quarterly technical progress report No. 5, July 28--October 28, 1991

Description: The material presented here has been described to some extent in Status Reports 12, 13, and 14 and covers the progress toward the synthesis of the modified target molecules 9-isopropyl-4-methoxy-6-methyldibenzothiophene (13) and 9-isopropyl-6-methyldibenzothiophene-4-ol (14). It is divided into three parts: (a) Dehydrogenation experiments On tetrahydrodibenzothiophene 12. (b) methoxyl methyl cleavage of 13 to 14 using boron tribromide. (c) isolation and purification of methoxydibenzothiophene 13.
Date: October 28, 1991
Partner: UNT Libraries Government Documents Department

Heteronuclear probes of coal structure and reactivity. Semi-annual report

Description: Efforts toward quantitation of the sulfur removed from coal in the reaction Coal(S) + excess PBu{sub 3} with heat {r_arrow} Coal + SPBu{sub 3}/PBu{sub 3} by column chromatography of the products followed by weighing the SPBu{sub 3} and vacuum distillation of the SPBu{sub 3}/PBu{sub 3} mixture followed by gas chromatographic analysis are described. The first method failed, but the latter is more successful. It has been discovered that para-chloro phenol catalyzes the removal of sulfur from dibenzothiophene by PBu{sub 3} under mild conditions.
Date: May 1, 1996
Creator: Verkade, J.G.
Partner: UNT Libraries Government Documents Department

Biodesulfurization of dibenzothiophene and crude oil using electro-spray reactors

Description: Biological removal of organic sulfur from petroleum feedstocks offers an attractive alternative to conventional thermochemical treatment due to the mild operating conditions afforded by the biocatalyst. In order for biodesulfurization to realize commercial success, reactors must be designed which allow for sufficient liquid / liquid and gas / liquid mass transfer while simultaneously reducing operating costs. In this study, the use of electric field contactors for the biodesulfurization of the model compound dibenzothiophene (DBT) as well as actual crude oil is investigated. The emulsion phase contactor (EPC) creates an emulsion of aqueous biocatalyst in the organic phase by concentrating forces at the liquid / liquid interface rather than imparting energy to the bulk solution as is done in impeller-based reactors. Characterization of emulsion quality and determination of rates of DBT oxidation to 2- hydroxybiphenyl (2-HBP) were performed for both batch stirred reactors (BSR) and the EPC. The EPC was capable of producing aqueous droplets of about 5 {micro}m in diameter using 3 W/L whereas the impeller-based reactor formed droplets between 100 and 200 {micro}m with comparable power consumption. The presence of electric fields was not found to adversely affect biocatalytic activity. Despite the greater surface area for reaction afforded by the EPC, rates of DBT oxidation in both reactors were similar, demonstrating that the biocatalyst used (Rhodococcus sp. IGTS8) was not active enough to be mass transport limited. The EPC is expected to have tremendous impact upon reactor operating costs and biocatalyst utilization once advances biocatalyst development provide systems that are mass transport limited.
Date: October 1, 1996
Creator: Kaufman, E.N.; Harkins, J.B.; Rodriguez, M.; Tsouris, C. & Selvaraj, P.T.
Partner: UNT Libraries Government Documents Department

SULFUR REDUCTION IN GASOLINE AND DIESEL FUELS BY EXTRACTION/ADSORPTION OF REFRACTORY DIBENZOTHIOPHENES

Description: The purpose of this study was to remove thiophene, benzothiophene and dibenzothiophene from a simulated gasoline feedstock. We found that Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+} reacts with a variety of thiophenes (Th*), affording Ru(NH{sub 3}){sub 5}(Th*){sup 2+}. We used this reactivity to design a biphasic extraction process that removes more than 50% of the dibenzothiophene in the simulated feedstock. This extraction system consists of a hydrocarbon phase (simulated petroleum feedstock) and extractant Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+} in an aqueous phase (70% dimethylformamide, 30% H{sub 2}O). The DBT is removed in situ from the newly formed Ru(NH{sub 3}){sub 5}(DBT){sup 2+} by either an oxidation process or addition of H{sub 2}O, to regenerate Ru(NH{sub 3}){sub 5}(H{sub 2}O){sup 2+}.
Date: March 1, 2003
Creator: McKinley, Scott G. & Alvarez, Celedonio M.
Partner: UNT Libraries Government Documents Department

Synthesis of 6-Methyl-9-n-propyldibenzo thiophene-4-ol ammended to 6-Methyl-9-(1-methylethyl)-dibenzo thiophene-4-ol. Quarterly technical progress report No. 6, October 28, 1991--January 26, 1992

Description: The material presented below is taken from Status Reports 15, 16 and 17 and covers the progress made toward the synthesis of the modified target molecules 9-isopropyl-4-methoxy-6 methyldibenzothiophene (13) and 9-isopropyl-6methyldibenzothiophene-4-ol (14).
Date: February 28, 1992
Partner: UNT Libraries Government Documents Department

THE BIOCATALYTIC DESULFURIZATION PROJECT

Description: The analysis of Petro Star diesel sulfur species is complete and a report is attached. Further analytical efforts will concentrate on characterization of diesel fuel, hydrodesulfurized to varying degrees, in order to determine sulfur species that may be problematic to hydrogen treatment and represent potential target substrates for biodesulfurization in a combined HDS-BDS process. Quotes have been received and are being considered for the partial treatment of Petro Star Inc. marine diesel fuel. Direction of research is changing slightly; economic analysis of the hyphenated--BDSHDS, BDS-CED--has shown the highest probability of success to be with a BDS-HDS process where the biodesulfurization precedes hydrodesulfurization. Thus, the microorganisms will be tailored to focus on those compounds that tend to be recalcitrant to hydrodesulfurization and decrease the severity of the hydrodesulfurization step. A separate, detailed justification for this change is being prepared. Research activities have continued in the characterization of the desulfurization enzymes from multiple sources. Genes for all DszA, -B, -C and -D enzymes (and homologs) have been cloned and expressed. Activity determinations, on a variety of substituted benzothiophene and dibenzothiophene substrates, have been carried out and continue. In addition, chemical synthesis efforts have been carried out to generate additional substrates for analytical standards and activity determinations. The generation of a GSSM mutant library of the ''Rhodococcus IGTS8 dszA'' gene has been completed and development of protocols for a high throughput screen to expand substrate specificity are nearing completion. In an effort to obtain improved hosts as biocatalyst, one hundred-thirty ''Rhodococcus'' and related strains are being evaluated for growth characteristics and other criteria deemed important for an optimal biocatalyst strain. We have also begun an effort to generate derivatives of the entire IGTS8 BDS plasmid that will allow for its easy transfer and manipulation into a variety of hosts. To support this activity ...
Date: October 1, 2003
Creator: Collins, Scott & Nunn, David
Partner: UNT Libraries Government Documents Department

A NOVEL APPROACH TO CATALYTIC DESULFURIZATION OF COAL

Description: Column chromatographic separation of the S=PBu{sub 3}/PBu{sub 3} product mixture followed by weighing the S=PBu{sub 3}, and by vacuum distillation of S=PBu{sub 3}/PBu{sub 3}mixture followed by gas chromatographic analysis are described. Effects of coal mesh size, pre-treatment with methanol Coal (S) + excess PR{sub 3} {yields} Coal + S=PR{sub 3}/PBu{sub 3} and sonication on sulfur removal by PBu{sub 3} revealed that particle size was not observed to affect desulfurization efficiency in a consistent manner. Coal pretreatment with methanol to induce swelling or the addition of a filter aid such as Celite reduced desulfurization efficiency of the PBu{sub 3} and sonication was no more effective than heating. A rationale is put forth for the lack of efficacy of methanol pretreatment of the coal in desulfurization runs with PBu{sub 3}. Coal desulfurization with PBu{sub 3} was not improved in the presence of miniscule beads of molten lithium or sodium as a desulfurizing reagent for SPBu{sub 3} in a strategy aimed at regenerating PBu{sub 3} inside coal pores. Although desulfurization of coals did occur in sodium solutions in liquid ammonia, substantial loss of coal mass was also observed. Of particular concern is the mass balance in the above reaction, a problem which is described in some detail. In an effort to solve this difficulty, a specially designed apparatus is described which we believe can solve this problem reasonably effectively. Elemental sodium was found to remove sulfur quantitatively from a variety of polycyclic organosulfur compounds including dibenzothiophene and benzothiophene under relatively mild conditions (150 C) in a hydrocarbon solvent without requiring the addition of a hydrogen donor. Lithium facilitates the same reaction at a higher temperature (254 C). Mechanistic pathways are proposed for these transformations. Curiously, dibenzothiophene and its corresponding sulfone was virtually quantitatively desulfurized in sodium solutions in liquid ammonia at -33 C, ...
Date: November 1, 2001
Creator: Verkade, John G.
Partner: UNT Libraries Government Documents Department

Synthesis of 6-Methyl-9-n-propyldibenzothiophene-4-ol ammended to 6-Methyl-9-(1-methylethyl)-dibenzothiophene-4-ol

Description: The material presented below is taken from Status Reports 15, 16 and 17 and covers the progress made toward the synthesis of the modified target molecules 9-isopropyl-4-methoxy-6 methyldibenzothiophene (13) and 9-isopropyl-6methyldibenzothiophene-4-ol (14).
Date: February 28, 1992
Partner: UNT Libraries Government Documents Department

Synthesis of 6-Methyl-9-n-propyldibenzothiophene-4-ol

Description: The material presented here has been described to some extent in Status Reports 12, 13, and 14 and covers the progress toward the synthesis of the modified target molecules 9-isopropyl-4-methoxy-6-methyldibenzothiophene (13) and 9-isopropyl-6-methyldibenzothiophene-4-ol (14). It is divided into three parts: (a) Dehydrogenation experiments On tetrahydrodibenzothiophene 12. (b) methoxyl methyl cleavage of 13 to 14 using boron tribromide. (c) isolation and purification of methoxydibenzothiophene 13.
Date: October 28, 1991
Partner: UNT Libraries Government Documents Department

Biocatalytic removal of organic sulfur from coal

Description: The objective is to characterize more completely the biochemical ability of the bacterium, Rhodococcus rhodochrous IGTS8, to cleave carbon-sulfur bonds with emphasis on data that will allow the development of a practical coal biodesulfurization process. Another approach for increasing the desulfurization activity of the IGTS8 cultures is to produce strains genetically that have higher activity. The goal of this part of research is to achieve strain improvement by introducing a stronger promoter using genetic engineering techniques. The promoter regulates the transcription of the genes for the desulfurization enzymes, and a stronger promoter, would up-regulate the expression of these genes, resulting in cells with higher desulfurization activity. Promoter probe vectors are used to identify and isolate promoters from a DNA library of the experimental organism. The major accomplishments have been to obtain high biodesulfurization activity in nonaqueous, media, especially using freeze-dried cells, and to have isolated strong promoters from R. rhodochrous IGTS8 which will be used to engineer the organism to produce strains with higher biocatalytic activity.
Date: September 9, 1994
Creator: Webster, D.A. & Kilbane, J.J. II
Partner: UNT Libraries Government Documents Department

Biodesulfurization techniques: Application of selected microorganisms for organic sulfur removal from coals. Final report

Description: As an alternative to post-combustion desulfurization of coal and pre-combustion desulfurization using physicochemical techniques, the microbial desulfurization of coal may be accomplished through the use of microbial cultures that, in an application of various microbial species, may remove both the pyritic and organic fractions of sulfur found in coal. Organisms have been isolated that readily depyritize coal but often at prohibitively low rates of desulfurization. Microbes have also been isolated that may potentially remove the organic-sulfur fraction present in coal (showing promise when acting on organic sulfur model compounds such as dibenzothiophene). The isolation and study of microorganisms demonstrating a potential for removing organic sulfur from coal has been undertaken in this project. Additionally, the organisms and mechanisms by which coal is microbially depyritized has been investigated. Three cultures were isolated that grew on dibenzothiophene (DBT), a model organic-sulfur compound, as the sole sulfur source. These cultures (UMX3, UMX9, and IGTS8) also grew on coal samples as the sole sulfur source. Numerous techniques for pretreating and ``cotreating`` coal for depyritization were also evaluated for the ability to improve the rate or extent of microbial depyritization. These include prewashing the coal with various solvents and adding surfactants to the culture broth. Using a bituminous coal containing 0.61% (w/w) pyrite washed with organic solvents at low slurry concentrations (2% w/v), the extent of depyritization was increased approximately 25% in two weeks as compared to controls. At slurry concentrations of 20% w/v, a tetrachloroethylene treatment of the coal followed by depyritization with Thiobacillus ferrooxidans increased both the rate and extent of depyritization by approximately 10%.
Date: August 1, 1993
Creator: Elmore, B. B.
Partner: UNT Libraries Government Documents Department

Protocols for the selective cleavage of carbon-sulfur bonds in coal. Technical report, March 1, 1992--May 30, 1992

Description: Chemical reactions that result in carbon-sulfur bond cleavage are an essential aspect of any protocol designed to remove organic sulfur from coal. Unfortunately, several classes of reactions that lead to carbon-sulfur bond cleavage are not well understood. Planned in ``Protocols for the Selective Cleavage of Carbon-Sulfur Bonds in Coal`` are reactions in which organic sulfur-containing coal model compounds are subjected to different conditions of temperature, solvent mixtures and radiation. Summarized in this quarterly report are results of our investigations of the following topics: (a) the reactions of coal model compounds, namely, benzyl phenyl sulfide (BPS), diphenyl sulfide (hereafter referred to as phenylsulfide, PS) and dibenzothiophene (DBT) with various reagents (Lewis acid catalysts, radical initiators, electron acceptors) using different solvents and temperature in an attempt to maximize the degree of carbon-sulfur (C-S) bond cleavage; and (b) the results of photooxidation of coal model compounds under controlled conditions. Quantitative product analyses are presented in this report.
Date: October 1, 1992
Creator: Bausch, M.
Partner: UNT Libraries Government Documents Department

Kinetics and mechanism of desulfurization and denitrogenation of coal-derived liquids. Fourteenth quarterly report, September 21, 1978-December 20, 1978

Description: Quantitative measurement of the reactivities of methyl-substituted dibenzothiophenes, under high pressure reaction conditions (102 atm, 300/sup 0/C) representative of industrial practice, has been accomplished. The catalyst was sulfided commercial Co-Mo/..gamma..-Al/sub 2/O/sub 3/. Methyl groups in the 2 and 8 or 3 and 7 positions show little effect. Methyl groups in the 4 position, however, reduced the reactivity by an order of magnitude and methyl groups in the 4 and 6 positions reduced it somewhat more. Dibenzothiophene (DBT) was found to be self-inhibiting and results with the methyl-substituted compounds implies that there is competitive adsorption of DBT and the methyl-substituted DBT. The reaction network involving benzonaphthothiophene and hydrogen has been determined. As before, the catalyst was typical commercial cobalt molybdate (sulfided CoO-MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/). The reaction conditions were 68 atm and 300/sup 0/C. The important result was that in contrast to dibenzothiophene, benzonaphthothiophene experiences extensive hydrogenation accompanying hydrodesulfurization, even with Co-Mo/..gamma..-Al/sub 2/O/sub 3/, the most selective of the available hydrodesulfurization catalysts. The sulfur-containing compounds having 3 rings or fewer experience nearly stoichiometric hydrodesulfurization (hydrogenolysis without hydrogenation), whereas the sulfur-containing compounds having 4 rings or more experience hydrogenation and hydrodesulfurization at roughly equal rates, giving products which experience further hydrogenation (and/or hydrodesulfurization - as the compound allows), again at roughly the same rates.
Date: March 16, 1979
Creator: Gates, B. C.; Katzer, J. R.; Olson, J. H.; Kwart, H. & Stiles, A. B.
Partner: UNT Libraries Government Documents Department

Applications of micellar enzymology to clean coal technology

Description: This project is designed to develop methods for pre-combustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid Dibenzothiophene (DBT) and ethlyphenylsulfide (EPS) are serving as models of organic sulfur-containing components of coal in initial studies. A goal of this project is to define a reverse micelle system that optimizes the catalytic activity of enzymes toward desulfurization of model compounds and ultimately coal samples. Among the variables which will be examined are the surfactant, the solvent, the water:surfactant ration and the pH and ionic strength of the aqueous phase. Studies were carried out with HRP, Type I RZ=1.2 and Type VI RZ=3.2 and laccase from Polyporus versicolor. Substrates for HRP assays included hydrogen peroxide, DBT, DBT sulfoxide, and DBT sulfone. Buffers included sodium phosphate. For formation of reverse micelle solutions the surfactant AOT, di(2-ethyl-hexyl)sodium sulphosuccinate, was obtained from Sigma Chemical Co. Isooctant was used as organic solvent. 12 refs., 5 figs., 3 tabs.
Date: October 26, 1990
Creator: Walsh, C.T.
Partner: UNT Libraries Government Documents Department

Molecular biological enhancement of coal desulfurization

Description: The objective of this project is to produce one or more microorganisms capable of removing the organic and inorganic sulfur in coal. The specific technical objectives of the project are to: clone and characterize the genes encoding the enzymes of the 4S'' pathway (sulfoxide/sulfone/sulfonate/sulfate) for release of organic sulfur from coal; return multiple copies of genes to the original host to enhance the biodesulfurization activity of that organism; transfer this pathway into a fast-growing chemolithotrophic bacterium; and conduct a batch-mode optimization/analysis of scale-up variables. This report presents the results of research at Battelle during the 5th Quarterly Report period beginning on June 15, 1990. 1 ref., 6 figs., 4 tabs.
Date: September 14, 1990
Creator: Litchfield, J.H.; Fry, I.; Wyza, R.E.; Palmer, D.T.; Zupancic, T.J.; Conkle, H.N. (Battelle, Columbus, OH (USA)) et al.
Partner: UNT Libraries Government Documents Department

Synthesis of model compounds for coal liquefaction research

Description: The objectives of this project are to develop feasible synthetic routes to produce (1) 4(4{prime}- hydroxy- 5{prime},6{prime},7{prime},8{prime}- tetrahydro-1{prime}- naphthylmethyl)- 6-methyl dibenzothiophene, and (2) a 1-hydroxy naphthalene- dibenzothiophene polymer. These compounds are thought to be representative of sulfur containing molecules in coal. The program is divided into three tasks, the first of which is a project work plan that we have already submitted. Our experimental work during this quarter concentrated on Task 2: Synthesis of 4(4{prime}- hydroxy- 5{prime},6{prime},7{prime},8{prime}- tetrahydro-1{prime}- naphthylmethyl)- 6-methyldibenzothiophene. 11 refs.
Date: November 2, 1990
Creator: Hirschon, A.S.; Asaro, M. & Bottaro, J.
Partner: UNT Libraries Government Documents Department

Applications of micellar enzymology to clean coal technology

Description: This project is designed to develop methods for precombustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid (Figure 1). Dibenzothiophene (DBT) and ethylphenylsulfide (EPS) are serving as models of organic sulfur-containing components of coal in initial studies. A goal of this project is to define a reverse micelle system that optimizes the catalytic activity of enzymes toward desulfurization of model compounds and ultimately coal samples. 12 refs., 2 figs., 7 tabs.
Date: October 21, 1991
Creator: Walsh, C.T.
Partner: UNT Libraries Government Documents Department

Solvent tailoring in coal liquefaction. Quarterly report, May 1982-August 1982. [Comparison of subcritical and supercritical conditions]

Description: The initial objective of this work was to study the phase distribution of donor solvents and solvent mixtures during the liquefaction of coal, to investigate the effects of phase distribution on coal conversion, and to determine the advantages, if any, of operating at subcritical and/or supercritical conditions. Computer simulations were used to predict the phase distribution, for various binary systems, as a function of temperature. The FLASH program was used to theoretically predict phase distribution for various model systems. Due to limitations in the computer program, success was achieved only in a few cases. Even in these cases, the existence of two-phase regions was observed only at temperatures and pressures far below normal liquefaction conditions. An extensive review of the literature was carried out in order to survey methods of experimentally studying vapor-liquid equilibria. Finally, some preliminary laboratory studies were carried out with the use of benzothiophene-dodecane as the model reaction system. It was felt that the study of the effect of reactor configuration on conversion would provide insight into whether phase distribution or mass transfer was the limiting consideration for coal conversion. However, no conclusive results were obtained from these studies.
Date: January 1, 1982
Creator: Tarrer, A.R.; Guin, J.A.; Curtis, C.W. & Williams, D.C.
Partner: UNT Libraries Government Documents Department

Kinetics and mechanism of desulfurization and denitrogenation of coal-derived liquids. Sixth quarterly report, September 21, 1976--December 20, 1976

Description: Two high-pressure flow microreactors continue to function effectively for studies of the hydrodesulfurization of dibenzothiophene, methyl-substituted dibenzothiophene and also for studies of the hydrodenitrogenation of quinoline. The hydrodesulfurization of dibenzothiophene has been examined in a flow system in a totally reproducible fashion free from catalyst deactivation for extended periods. The reaction is first-order in dibenzothiophene, and all of the reaction products except H/sub 2/S are sulfur free. A program for determining the kinetics and reaction network of methyl-substituted dibenzothiophenes was started. For example, the rate for hydrodesulfurization of 4,6-dimethyldibenzothiophene is about one-fifth the rate for dibenzothiophene. The hydrocarbon reaction products except H/sub 2/S are sulfur free; therefore, the initial point of attack is concluded to be the C-S bond. The hydrodenitrogenation of quinoline was examined further by replacing white oil with hexadecane; this substitution permits the determination of the nitrogen-free reaction products by gas chromatography. These studies show that the C-N bond is broken after at least the heterocyclic ring and preferably both rings are hydrogenated. The hydrogenolysis reactions are rate limiting for the overall process of nitrogen removal. The hydrodenitrogenation of acridine is slower than that of quinoline. The reaction network shows that the molecule must be hydrogenated before nitrogen removal occurs at a significant rate.
Date: December 22, 1976
Creator: Gates, B. C.; Katzer, J. R.; Olson, J. H.; Kwart, H. & Stiles, A. B.
Partner: UNT Libraries Government Documents Department

Interactions of selected bacterial isolates with DBT and solubilized coal

Description: We are studying the interactions of isolated bacteria with dibenzothiophene (DBT), a sulfur-containing model compound, and with a solubilized coal product derived from a high-organic-sulfur lignite. The sensitivity of the tetrazolium assay used to identify and study these strains was improved by substituting tetrazolium violet for triphenyltetrazolium. DBT metabolism by thirteen strains was investigated using qualitative and quantitative GC and GC-MS analyses. Growth medium and incubation time affect the extent of DBT degradation and the production of DBT metabolites. Under specific conditions, seven of the strains produce metabolites which elute close to the position of one or another of the biphenyl standards. However, when these samples are spiked with the standard compounds, the bacterial metabolites do not co-elute with the standards. The modification of solubilized high-organic-sulfur coal by six of these strains was also studied. No selective removal of sulfur relative to carbon was observed. 13 refs., 1 fig., 2 tabs.
Date: January 1, 1990
Creator: Key, D.H.; Fox, R.V.; Kase, R.S.; Willey, M.S.; Stoner, D.L. & Ward, T.E.
Partner: UNT Libraries Government Documents Department

(Electrochemical hydrogenation and hydrogenolysis in aqueous media)

Description: We focused on preparative reductions at mercury cathodes in media containing tetraalkylammonium (TAA{sup +}) electrolytes. Using these conditions the cathodic reduction of functional groups which are electroinactive within the accessible potential window'' has been achieved and several simple, but selective organic syntheses were performed. Quite a number of functional groups are reduced at this limit of the cathodic potential window.'' The reduction of benzene, alkynes, alkenes, polycyclic aromatic hydrocarbons, phenanthrene, and benzothiophene is described. The research could be applied to areas such as coal hydrogenation. 6 tabs.
Date: January 1, 1989
Creator: Kariv-Miller, E.
Partner: UNT Libraries Government Documents Department

Studies in coal liquefaction with application to the SRC and related processes. Quarterly report, August 1981-October 1981. [Using model compounds]

Description: Model compound reactions were studied to evaluate the effects of mass transfer, solvent type, solvent blending, hydrogen partial pressure, temperature, reactant concentration, additive loading and its preparation, etc. Naphthalene hydrogenation and benzothiophene hydrodesulfurization were investigated under the conditions comparable to commercial coal liquefaction and related processes. Both of these reaction systems were observed to be surface reaction controlled under the reaction conditions used in this work. Certain aromatic compounds were observed to cause a reduction in the reaction rates of naphthalene and benzothiophene. Single stage coal dissolution was investigated using tetralin as a hydrogen donor solvent and a commercial cobalt-molybdate catalyst. A spinning basket system was developed to allow injection of the catalyst at a desired time in the reaction cycle. This catalyst injection technique proved to be reliable for the exploratory work done here. The degree of catalyst deactivation was rated by comparing the activities of the spent catalyst for model compound (naphthalene and cumene) reactivities relative to those of the fresh catalyst. No substantial reduction in deactivation was observed to result with delayed contacting of the catalyst with the coal-tetralin reaction mixture. The effect of reaction temperature on the initial rate of catalyst deactivation was also studied.
Date: January 1, 1981
Creator: Tarrer, A. R.; Guin, J. A. & Curtis, C. W.
Partner: UNT Libraries Government Documents Department