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Analysis of the radical hydrogen transfer pathway for cleaving strong bonds in coal

Description: Hydrogen transfer processes involving radical intermediates are of key importance in the liquefaction of coal. While the primary function of donor solvents is to transfer H{lg_bullet} to coal-derived radicals that form when weak bonds are cleaved thermolytically, growing evidence suggests that the donor solvent can play a role in promoting cleavage of strong {alpha}-bonds. McMillen and Malhotra have explained the results in terms of a single-step mechanism referred to as radical H-transfer (RHT). Mechanistic kinetic models have been used to suggest the importance of RHT pathways in anthracene- and pyrene-based solvent systems. However, we question the reliability of these approaches because little experimental data exists to support the 16.5 kcal/mol intrinsic barriers they assume for RHT reactions. Unambiguous evidence for RHT is very difficult to obtain experimentally because at the temperatures required to activate the RHT reaction, a suite of multistep reactions can occur, which yield the same products, i.e. H-elimination from hydroaryl radicals followed by ipso addition. For this reason, we have sought to gain insight to barrier heights for RHT from theory. This paper reports our use of Marcus theory in combination with ab initio and semiempirical molecular orbital methods to show how the intrinsic barriers for RHT reactions depend on structural and thermodynamic properties of the reacting partners. In addition, reactions thought to be mediated by RHT are reexamined using mechanistic kinetic modeling (MKM) to determine the extent to which these reactions can be explained by conventional pathways.
Date: September 1, 1993
Creator: Autrey, S. T.; Camaioni, D. M.; Ferris, K. F. & Franz, J. A.
Partner: UNT Libraries Government Documents Department

Hydrogen shutting pathways in thermal hydroliquefaction: Solvent-induced scission of coal model compound structures

Description: It has been demonstrated that donor solvents play a key role in the scission of thermal stable bonds in coal model compounds and therefore it has been speculated that they will improve liquefaction efficiencies. The authors have been studying the transfer of hydrogen from dihydroarene donor solvents to arene model compounds to quantify the barriers of competing hydrogen transfer mechanisms. Hydrogen can be transferred between arene rings by a variety of pathways. The specific hydrogen transfer pathway or pathways can be predicted given an understanding of the thermochemistry of the reactants intermediates and products. The individual pathways that contribute to strong bond scission have been shown to be dependent on the dihydroarene donor and the arene acceptor. In this paper they quantify the hydrogen pathways between the solvent components anthracene and phenanthrene. In addition, they describe reaction conditions requiring consideration of an additional hydrogen transfer pathway: a multi-step nonipso hydrogen transfer to coal model compounds to evaluate the hydrogen transfer steps to cleave strong diarylmethane bonds in coal structures.
Date: September 1, 1995
Creator: Autrey, S.T.; Powers, T.; Alborn, E.A.; Camaioni, D.M. & Franz, J.A.
Partner: UNT Libraries Government Documents Department

Catalytic conversion of polycyclic aromatic hydrocarbons: Mechanistic investigations of hydrogen transfer from an iron-based catalyst to alkylarenes

Description: Results of our model compound studies suggest that free radical hydrogen transfer pathways from the catalyst to the alkylarene are responsible for the scission of strong carbon-carbon bonds. There are two requisites for the observed selective bond scission. First is the stability of the ipso adduct precursor leading to displacement, the more stable the adduct the more probable bond scission. This explains why benzyl radical displacement > phenoxy radical displacement in benzyldiphenyl ether and explains why PhCH{sub 2}CH{sub 2}PhCH{sub 2} radical > naphthylmethyl radical from NMBB. Second, given equal ipso adduct precursor stabilities, e.g. methyldiphenylmethane, the stability of the departing radical determines the selectivity. this explains benzyl radical > methyl radical in the methylated diphenylmethanes and explains why {alpha}-hydroxyphenethyl radical > methyl radical in 1,2-ditolylethanol. We have assumed little physical interaction between the molecules and the catalytic surface and have been able to satisfactorily explain most of the observed selectivity. However, for NMBB we expect a higher selectivity for -A- bond scission relative to -B- bond scission, given the ca. 6 kcal/mol difference between the radical adduct formed by the hydrogen atom addition to 1-methylnaphthalene and p-xylene. It is possible that physical properties play a role in lowering the selectivity in -B- bond scission. Also, catalysts prepared by other methods may contain different activity sites and operate by different mechanisms.
Date: August 1, 1995
Creator: Autrey, T.; Linehan, J.C.; Camaioni, D.M.; Powers, T.R.; McMillan, E.F. & Franz, J.A.
Partner: UNT Libraries Government Documents Department

Investigation of the use of a recycle stream to mediate hydrogen transfer to improve the conversion of eastern oil shale to liquid products

Description: The processing of eastern oil shale has long been known to require the addition of hydrogen to increase the oil yield. Several researchers, have investigated the use of both high pressure hydrogen and hydrogen donor solvents. Much of the donor solvent work has used pure,compounds such as tetralin and has not addressed the use of-a more realistic solvent such as one derived from the production process itself. The work reported herein is for the research Task 1.2.2, Process Studies, in the Annual Project Plan, October l, 1990--September 30, 1991, of the Cooperative Agreement. In the study, a shale oil-derived, recycle oil was used to mediate the transfer of hydrogen to eastern oil shale. The work was divided into two main parts which correspond to the two main portions of the Hydrogen-Extraction (H-E{trademark}) process: (1) the shale oil extraction which involves the use of a donor solvent to aid in the extraction of the shale oil and (2) the regeneration of the donor solvent to a hydrogen-rich state ready for recycle. The results of the investigation to evaluate shale oil extraction using a shale oil-derived donor solvent suggest that temperature had the, greatest effort on organic conversion. At a temperature of 425{degrees}C (197{degrees}F), a yield of 130% of Fischer assay was obtained using tetralin as a donor solvent. At the same temperature, only 110% of Fischer assay could be obtained using a middle distillate as a donor solvent.
Date: June 1, 1944
Creator: Barbour, F. A.; Guffey, F. D.; Thomas, K. P. & Blake, R. F.
Partner: UNT Libraries Government Documents Department

Genetic and biochemical analysis of solvent formation in Clostridium acetobutylicum

Description: The anaerobic organism Clostridium acetobutylicum has been used for commercial production of important organic solvents due to its ability to convert a wide variety of crude substrates to acids and alcohols. Current knowledge concerning the molecular genetics, cell regulation and metabolic engineering of this organism is still rather limited. The objectives are to improve the knowledge of the molecular genetics and enzymology of Clostridia in order to make genetic alterations which will more effectively channel cell metabolism toward production of desired products. Two factors that limit butanol production in continuous cultures are: (1) The degeneration of the culture, with an increase in the proportion of cells which are incapable of solvent production. Currently isolated degenerate strains are being evaluated to analyze the molecular mechanism of degeneration to determine if it is due to a genetic loss of solvent related genes, loss of a regulatory element, or an increase in general mutagenesis. Recent studies show two general types of degenerates, one which seems to have lost essential solvent pathway genes and another which has not completely lost all solvent production capability and retains the DNA bearing solvent pathway genes. (2) The production of hydrogen which uses up reducing equivalents in the cell. If the reducing power were more fully directed to the reduction reactions involved in butanol production, the process would be more efficient. The authors have studied oxidation reduction systems related to this process. These studies focus on ferredoxin and rubredoxin and their oxidoreductases.
Date: May 1, 1998
Creator: Bennett, G.N. & Rudolph, F.B.
Partner: UNT Libraries Government Documents Department

Restricted mass transport effects on free radical reactions

Description: Coal possesses a complex chemical and physical structure. The cross-linked, network structure can lead to alterations in normal thermally-induced, free-radical decay pathways as a consequence of restrictions on mass transport. Moreover, in coal liquefaction, access of an external hydrogen donor to a reactive radical site can be hindered by the substantial domains of microporosity present in coals. However, previous work indicates that diffusion effects do not appear to be playing an important role in this coal conversion chemistry. Several possible explanations for this phenomenon were advanced including the potential involvement of a hydrogen hopping/radical relay mechanism recently discovered model systems in the authors laboratories. The authors have employed silica-anchored compounds to explore the effects of restricted mass transport on the pyrolysis mechanisms of coal model compounds. In studies of two-component systems, cases have been discovered where radical centers can be rapidly relocated in the diffusionally constrained environment as a consequence of rapid serial hydrogen atom transfers. This chemistry can have substantial effects on thermal decomposition rates and on product selectivities. In this study, the authors examine additional surfaces to systematically investigate the impact of molecular structure on the hydrogen atom transfer promoted radical relay mechanism. Silica-attached 1,3-diphenylpropane ({approx}Ph(CH{sub 2}){sub 3}Ph, or {approx}DPP) was chosen as the thermally reactive component, since it can be considered prototypical of linkages in coal that do not contain weak bonds easily cleaved at coal liquefaction temperatures (ca. 4000 {degrees}C), but which crack at reasonable rates if benzylic radicals can be generated by hydrogen abstraction. The rate of such hydrogen transfers under restricted diffusion will be highly dependent on the structure and proximity of neighboring molecules.
Date: September 1, 1994
Creator: Buchanan, A. C. III; Britt, P. F. & Thomas, K. B.
Partner: UNT Libraries Government Documents Department

The role of recycle oil in direct coal liquefaction process development

Description: It has long been recognized that use of a recycle oil is a convenient and perhaps necessary feature of a practical direct coal liquefaction process. The recycle oil performs a number of important functions. It serves as a vehicle to convey coal into the liquefaction reactor and products from the reactor. It is a medium for mass and heat transfer among the solid, liquid, and gaseous components of the reactor inventory. It can act as a reactant or intermediate in the liquefaction process. Therefore, the nature of the recycle oil can have a determining effect on process configuration and performance, and the characterization of recycle oil composition and chemistry has been the subject of considerable interest. This paper discusses recycle oil characterization and its influence on the industrial development of coal liquefaction technology,
Date: August 1, 1995
Creator: Burke, F. P.
Partner: UNT Libraries Government Documents Department

Exploratory research on novel coal liquefaction concept. [Quarterly report], January 1--March 31, 1996

Description: Work this quarter concentrated on evaluating the effects of low- severity, first stage reaction conditions on coal conversions, exploring the effect of solvent-to-coal ratio on filtration performance, exploring the effects of pretreatment on dispersed catalysts for hydrotreating tests, and the installation and calibration of a simulated distillation instrument. Additional work included continued review of the technical and patent literature and expansion of the annotated bibliography.
Date: May 9, 1996
Creator: Burke, F.P.; Brandes, S.D.; Winschel, R.A.; Derbyshire, F.J.; Kimber, G.; Anderson, R.K. et al.
Partner: UNT Libraries Government Documents Department

Exploratory Research on novel coal liquefaction concept. Technical progress, October 1--December 31, 1995

Description: The purpose of this coordinated research program is to explore a new approach to direct coal liquefaction in which the primary coal dissolution step is effected by chemical rather than thermal cleavage of bonds in the coal. This is done at a temperature which is significantly lower than that typically used in conventional coal liquefaction. Reaction at this low temperature results in high conversion of the coal to a solubilized form, with little hydrocarbon gas formed, and avoids the thermally induced retrograde reactions which are unavoidable in conventional thermal processes. In addition, for low-rank coals, a substantial portion of the oxygen in the coal is removed as CO and CO{sub 2} during the dissolution. The higher selectivity to liquid products and rejection of oxygen as carbon oxides should result in improved hydrogen utilization. The basis of this novel concept is the discovery made by CONSOL R&D that certain hydride transfer agents are very active for coal dissolution at temperatures in the range of 350{degrees}C. Activities during this quarter were conducted under Tasks 2 and 5. The Task 2 work was concentrated on evaluating the effects of first-stage reaction variables on coal conversion using the microautoclave, construction of a 1L reactor system for producing large quantities of first-stage reaction products, microfiltration tests with the first-stage products, and trial operation of the second-stage hydrotreater. Task 5 work was concentrated on the literature survey and defining the cost of production of the hydride ion reagent.
Date: December 31, 1995
Creator: Burke, F.P.; Winschel, R.A. & Brandes, S.D.
Partner: UNT Libraries Government Documents Department

Intrinsic barriers for H-atom transfer reactions involving hydrocarbons

Description: Intrinsic barriers (formally the barrier in the absence of driving force) for H-atom transfer reactions are key parameters in Evans-Polyanyi and Marcus equations for estimating exothermic reaction barriers and are fundamentally significant for the insight they provide about bond reorganization energies for formation of transition state structures. Although knowable from experiment, relatively few of these barriers have been measured due to experimental difficulties in measuring rates for identity reactions. Thus, the authors have used semiempirical Molecular Orbital theoretical methods (MNDO/PM3) to calculate barriers for a series of H-atom transfer identity reactions involving alkyl, alkenyl, arylalkyl and hydroaryl radicals and donors. Briefly stated, they find that barriers decrease with the degree of alkyl substitution at the radical site whereas barriers increase with the degree of conjugation with the radical site. Details of the methodology and analyses of how these barrier heights correlate with reactant and transition state properties will be presented and discussed.
Date: August 1, 1994
Creator: Camaioni, D. M.; Autrey, S. T. & Franz, J. A.
Partner: UNT Libraries Government Documents Department

Intrinsic barriers for H-atom transfer reactions

Description: Hydrogen transfer reactions play a well-recognized role in coal liquefaction. While H-abstraction reactions between radicals and H-donors have been well-studied, understanding of structure-reactivity relationships remains surprisingly incomplete. Another form of hydrogen transfer known as radical hydrogen transfer (radical donation of H to an unsaturated compound) is currently the subject of much speculation. The barriers for identity reactions are key parameters in the Evans-Polanyi equation for estimating reaction barriers and are fundamentally significant for the insight they provide about bond reorganization energies for formation of transition state structures. Although knowable from experiment, relatively few H-abstraction identity barriers and no barriers for hydrocarbon radical hydrogen transfer reactions have been measured. This paper seeks to supplement and extend existing experimental data with results obtained by calculation. The authors have used ab initio and semiempirical molecular orbital methods (MNDO-PM3) to calculate barriers for a series of H-atom abstraction and radical-hydrogen-transfer identity reactions for alkyl, alkenyl, arylalkyl and hydroaryl systems. Details of this methodology and analyses of how barrier heights correlate with reactant and transition state properties will be presented and discussed.
Date: August 1, 1994
Creator: Camaioni, D.M.; Autrey, S.T. & Franz, J.A.
Partner: UNT Libraries Government Documents Department

Coal-derived promoters for the liquefaction of Illinois coal. Technical report, September 1, 1991--November 30, 1991

Description: The objective of this program is to investigate the use of liquids derived from coal either by mild gasification or supercritical extraction (SCE) to promote direct liquefaction of Illinois coal. Some organic sulfur-, nitrogen-, and oxygen-containing compounds have been found to enhance liquefaction reactions. The use of Illinois coal to produce liquid fractions rich in these types of compounds could increase the rates of liquefaction reactions, thus improving the process economics. An integrated process combining direct liquefaction with mild gasification or SCE of coal is being developed by IGT. The approach taken in this two-year program is to use recently developed molecular probe techniques to assess the reactivity of three coal-derived liquids with respect to (A) hydrogen transfer rate, (B) carbon-carbon bond cleavage rate, (C) free radical flux, and (D) hydrocracking activity. Sample liquids from Illinois Basin Coal IBC-106 are prepared by three methods: mild gasification in an isothermal free-fall reactor (IFFR), steam treatment followed by mild gasification in a fixed-bed reactor (ST/FBR), and SCE using toluene in a batch autoclave. During the first year of the program, the IFFR and ST/FBR coal liquids were produced and characterized, and the IFFR liquid was assessed by the four molecular-probe methods. During the first quarter of the second year, reactivity testing and data analysis on the ST/FBR coal liquid was completed. For the ST/FBR liquid, hydrogen transfer rate showed a mean increase of 7%, C-C bond cleavage selectivity increased by 27%, free radical flux increased 101%, and data indicated a 227% increase in hydrocracking activity. 12 refs., 5 figs., 7 tabs.
Date: December 31, 1991
Creator: Carty, R. H.
Partner: UNT Libraries Government Documents Department

Coal-derived promoters for the liquefaction of Illinois coal. Final technical report, September 1, 1991--August 31, 1992

Description: The objective of this program was to investigate the use of liquids derived from coal either by mild gasification or supercritical extraction (SCE) to promote direct liquefaction of Illinois coal. In this two-year program recently developed molecular probe techniques were used to assess the activity of three coal-derived liquids with respect to accelerating (A) hydrogen transfer, (B) carbon-carbon bond cleavage, (C) free radical flux, and (D) hydrocracking activity. Three sample liquids were prepared from IBC-106 coal by: mild gasification in an isothermal free-fall reactor (IFFR), steam treatment/mild gasification in a fixed-bed reactor (ST/FBR), and SCE using toluene. For comparison, tests were also performed on a Wilsonville recycle solvent (RS) and on benzyl phenyl sulfide (BPS), a ``benchmark`` promoter. Sample/blank pairs were tested at 400--425{degrees}C in laboratory microreactors, and effectiveness was based on the increase in extent of a key reaction for each sample containing coal liquid, compared to its blank. In general, the IFFR liquid was the most effective liquid for promoting hydrogen transfer (+21%) and free radical flux (+107%), while the SCE liquid was the most effective promoter of C-C bond cleavage selectivity (+119%) and hydrocracking (+359%). The ST/FBR liquid was slightly less effective than the IFFR liquid in all categories. BPS was used primarily to validate the adequacy of the methods.
Date: December 31, 1992
Creator: Carty, R. H. & Knight, R. A.
Partner: UNT Libraries Government Documents Department

Coal-derived promoters for the liquefaction of Illinois coal

Description: The objective of this program is to investigate the use of liquids derived from coal either by mild gasification or supercritical extraction (SCE) to promote direct liquefaction of Illinois coal. Some organic sulfur-, nitrogen-, and oxygen-containing compounds have been found to enhance liquefaction reactions. The use of Illinois coal to produce liquid fractions rich in these types of compounds could increase the rates of liquefaction reactions, thus improving the process economics. An integrated process combining direct liquefaction with mild gasification or SCE of coal is being developed by IGT. The approach taken in this two-year program is to use recently developed molecular probe techniques to assess the reactivity of three coal-derived liquids with respect to (A) hydrogen transfer rate, (B) carbon-carbon bond cleavage rate, (C) free radical flux, and (D) hydrocracking activity. Sample liquids from Illinois Basin Coal IBC-106 are prepared by three methods: mild gasification in an isothermal free-fall reactor (IFFR), steam treatment followed by mild gasification in a fixed-bed reactor (ST/FBR), and SCE using toluene in a batch autoclave. During the first year of the program, the IFFR and ST/FBR coal liquids were produced and characterized, and the IFFR liquid was assessed by the four molecular-probe methods. During the first quarter of the second year, reactivity testing and data analysis on the ST/FBR coal liquid was completed. For the ST/FBR liquid, hydrogen transfer rate showed a mean increase of 7%, C-C bond cleavage selectivity increased by 27%, free radical flux increased 101%, and data indicated a 227% increase in hydrocracking activity. 12 refs., 5 figs., 7 tabs.
Date: January 1, 1991
Creator: Carty, R.H.
Partner: UNT Libraries Government Documents Department

Organometallic chemistry of bimetallic compounds. Final progress report

Description: This report consists of six sections: heterobimetallic dihydrides, early-late transition metal heterobimetallic compounds, amphiphilic carbene complexes and hydroxycarbene complexes, diiron compounds with bridging hydrocarbon ligands, diphosphine chelates with natural bite angles near 120 degrees, and synthesis and reactions of M=M compounds. (WET)
Date: July 1, 1991
Creator: Casey, C. P.
Partner: UNT Libraries Government Documents Department

Organometallic chemistry of bimetallic compounds

Description: This report consists of six sections: heterobimetallic dihydrides, early-late transition metal heterobimetallic compounds, amphiphilic carbene complexes and hydroxycarbene complexes, diiron compounds with bridging hydrocarbon ligands, diphosphine chelates with natural bite angles near 120 degrees, and synthesis and reactions of M=M compounds. (WET)
Date: July 1, 1991
Creator: Casey, C.P.
Partner: UNT Libraries Government Documents Department

New Albany shale flash pyrolysis under hot-recycled-solid conditions: Chemistry and kinetics, II

Description: The authors are continuing a study of recycle retorting of eastern and western oil shales using burnt shale as the solid heat carrier. Stripping of adsorbed oil from solid surfaces rather than the primary pyrolysis of kerogen apparently controls the release rate of the last 10--20% of hydrocarbons. Thus, the desorption rate defines the time necessary for oil recovery from a retort and sets the minimum hold-time in the pyrolyzer. A fluidized-bed oil shale retort resembles a fluidized-bed cat cracker in this respect. Recycled burnt shale cokes oil and reduces yield. The kerogen H/C ratio sets an upper limit on yield improvements unless external hydrogen donors are introduced. Steam can react with iron compounds to add to the H-donor pool. Increased oil yield when New Albany Shale pyrolyzes under hot-recycled-solid, steam-fluidization conditions has been confirmed and compared with steam retorting of acid-leached Colorado oil shale. In addition, with retorted, but unburnt, Devonian shale present at a recycle ratio of 3, the authors obtain 50% more oil-plus-gas than with burnt shale present. Procedures to make burnt shale more like unburnt shale can realize some increase in oil yield at high recycle ratios. Reduction with H{sub 2} and carbon deposition are possibilities that the authors have tested in the laboratory and can test in the pilot retort. Also, eastern spent shale burned at a high temperature (775 C, for example) cokes less oil than does spent shale burned at a low temperature (475 C). Changes in surface area with burn temperature contribute to this effect. 15 refs., 8 figs., 4 tabs.
Date: November 1, 1990
Creator: Coburn, T.T. & Morris, C.J.
Partner: UNT Libraries Government Documents Department

Hydrogen-transfer and charge transfer in photochemical and high energy radiation induced reactions: effects of thiols. Final report, February 1, 1960-january 31, 1979

Description: Absorption of ultraviolet or visible light, or high energy radiation, may lead to highly reactive free radicals. Thiols affect the reactions of these radicals in the following ways: (1) transfer of hydrogen from sulfur of the thiol to a substrate radical, converting the radical to a stable molecule, and the thiol to a reactive thiyl radical; and (2) transfer of hydrogen from a substrate radical or molecule to thiyl, regenerating thiol. The thiol is thus used repeatedly and a single molecule may affect the consequences of many quanta. Three effects may ensue, depending upon the system irradiated: (1) the substrate radicals may be converted by thiol-thiyl to the original molecules, and protection against radiation damage is afforded. (2) The radicals may be converted to molecules not identical with the starting materials, and in both cases damage caused by radical combination processes is prevented. (3) Product yields may be increased where the initial radicals might otherwise regenerate starting materials. It was shown that rates of reaction of excited species can be correlated with triplet energies and reduction potentials, and with ionization potentials, that amines are very reactive toward excited carbonyl compounds of all types, and that yields of products from these reactions can be increased by thiols, leading to increased efficiency in utilization of light.
Date: March 1, 1980
Creator: Cohen, S G
Partner: UNT Libraries Government Documents Department

Chemical structures and reactivities of coal as an organic natural product

Description: Some chemical reactions involved in coal liquefaction have been studied using carbon 14 labelled compounds and nuclear magnetic resonance. On the basis of these studies it is concluded that the role of tetralin during coal conversion is (1) to act as a dispersion vehicle; (2) to supply hydrogen radicals, when needed, to trap coal radicals, and (3) in a very minor way to undergo intermolecular reaction with the coal through making and breaking of C--C (and possibly other) bonds. As a result of other experiments it is concluded that to the methods previously employed for breaking bonds in coal molecules and thereby lowering their molecular weights, must now be added the use of solvated-electrons for breaking -CH/sub 2/--CH/sub 2/- linkages. A possible mechanism for the cleavage of bibenzyl (used as a model compound for coal) is given. (LTN)
Date: January 1, 1979
Creator: Collins, C J; Hombach, H P; Benjamin, B M; Roark, W H; Maxwell, B & Raaen, V F
Partner: UNT Libraries Government Documents Department

Coprocessing through fundamental and mechanistic studies in hydrogen transfer and catalysis. Quarterly report, December 27, 1991--March 27, 1992

Description: The research conducted this quarter evaluated hydrogen transfer from resids reduced using the Birch reduction method and their corresponding parent resid to an aromatic acceptor, anthracene (ANT). The reactions involved thermal and catalytic reactions using sulfur introduced as thiophenol. This catalyst has been shown by Rudnick to affect the hydrogen transfer from cycloalkane to aromatics/or coal. The purpose of this current study was to evaluate the efficacy of hydrogen transfer from the hydrogen-enriched reduced resid to an aromatic species and to compare that to the hydrogen transfer from the original resid. The analyses performed to evaluate hydrogen transfer were the determination of product slates from the hydrogenation of ANT and the fractionation of the resid into solubility fractions after reaction with ANT. The amount of coal conversion to THF solubles was higher in the coprocessing reactions with the reduced resids compared to the reactions with the corresponding untreated resid. The reduction of the resids by the Birch method increased the hydrogen donating ability of the resid to the same level as that obtained with the introduction of isotetralin (ISO) to the original resid. The ISO was introduced at a level of 0.5 wt % donable hydrogen. Both the original resids and the resids reduced by the Birch method were reacted in the presence of an aromatic species, anthracene (ANT). These reactions were performed under both nitrogen and hydrogen atmospheres at a pressure of 1250 psig introduced at ambient temperature. The reactions were performed both thermally and catalytically at 380{degree}C for 30 minutes. The catalyst used was thiophenol which is the same catalyst as has been used in the previously reported model compound studies involving hydrogen transfer from cycloalkanes to aromatics.
Date: December 31, 1992
Creator: Curtis, C. W.
Partner: UNT Libraries Government Documents Department

Coprocessing through fundamental and mechanistic studies in hydrogen transfer and catalysis. Quarterly report, March 28, 1992--June 30, 1992

Description: Hydrogen transfer from naphthenes to aromatics, coal, resid, and coal plus resid has been investigated at 430{degree}C in a N{sub 2} atmosphere. The reaction of perhydropyrene (PHP) with anthracene (ANT) resulted in the formation of pyrene (PYR) and dihydroanthracene. The weight percents of the products formed varied according to the initial ratio of ANT/PHP with a minimum appearing at a 2:1 weight ratio. Increased reaction times and high ANT/PHP ratios also yielded tetrahydroanthracene (THA). Reactions of Illinois No. 6 coal from the Argonne Premium Coal Sample Bank with PHP, ANT, and PYR resulted in higher coal conversion with PHP and lower with ANT and PYR. Reactions of PHP with resid resulted in less retrogressive reactions occurring in the resid than with either PYR or ANT. Apparent hydrogen transfer from coal or resid to ANT and PYR was observed. Combining PHP with ANT or PYR with coal, resid or coal plus resid yielded higher conversions and less retrogressive reactions. Hydrogen transfer occurred from PHP to ANT or PYR and to the coal and resid as evinced by the increased conversion.
Date: December 31, 1992
Creator: Curtis, C. W.
Partner: UNT Libraries Government Documents Department

Coprocessing through fundamental and mechanistic studies in hydrogen transfer and catalysis. Quarterly report, September 26, 1991--December 26, 1991

Description: The research conducted during this quarter evaluated hydrogen transfer from hydroaromatics and cyclic olefins to aromatics under thermal and catalytic conditions. The reactions under study involved thermal reactions of a cyclic olefin, isotetralin (ISO), with aromatics, anthracene (ANT) and pyrene (PYR). These reactions completed a set of experiments with hydrogen-rich species and aromatics previously reported that included cycloalkanes of perhydropyrene (PHP) and perhydroanthracene (PHA), hydroaromatic donors, tetralin (TET) and dihydroanthracene (DHA), cyclic olefins, hexahydroanthracene (HHA) and ISO, and aromatics, PYR and ANT. Catalytic reactions performed this quarter used a sulfur catalyst that had been shown by Rudnick to affect the hydrogen transfer from cycloalkanes to aromatics and/or coal. Rudnick investigated the dehydrogenation of alicyclic compounds converting them to the corresponding aromatic compounds in a process in which the alicyclic compounds served as hydrogen donors. Thiophenol and thiol were effective catalysts and helped promote the conversion of alicyclic compounds to aromatic compounds. The research performed in our laboratory focused on evaluating the effect of a sulfur catalyst on the transfer of hydrogen from cycloalkanes like perhydropyrene (PHP) to aromatics like anthracene under catalytic conditions. The catalyst used in this study was sulfur generated from thiophenol present at a concentration level of 2000 ppm of sulfur. The reactions were performed under two temperature conditions, 380 and 440{degrees}C; both thermal and catalytic reactions were performed for comparison. In addition, the individual cycloalkane and aromatic compounds were reacted under these conditions so that a direct comparison of the effect of temperature and of catalyst on the reaction products formed could be made.
Date: December 31, 1991
Creator: Curtis, C. W.
Partner: UNT Libraries Government Documents Department

Improved performance in coprocessing through fundamental and mechanistic studies in hydrogen transfer and catalysis. Final report, September 26, 1989--March 31, 1993

Description: The key results obtained from this research project are given: (1) Hydrogen transfer from naphthenes to aromatics, coal and resid occurred at coprocessing temperatures and in a N{sub 2} atmosphere; (2) Hydrogen donors ranked in reactivity as cyclic olefins (nonaromatic hydroaromatic compounds) > hydroaromatic compounds > naphthenes. This ranking held regardless of the type of atmosphere, hydrogen or nitrogen, used; (3) Resids reduced by the Birch method transferred substantially more hydrogen to the aromatic acceptor than did the parent resids under coprocessing conditions; (4) Hydropretreatment of resids resulted in enhanced coal conversion compared to the parent resid; (5) Addition of hydrogen donors such as cyclic olefins or hydroaromatic donors increased the amount of coal conversion during coprocessing. Cyclic olefins and the active hydroaromatic donor, dihydroanthracene, showed the highest level of hydrogen donability. Tetralin and octahydroanthracene showed low reactivity; (6) Reduced resids were more effective in coprocessing than the parent resids, in terms of enhanced coal conversion; (7) Thermal and catalytic reactivity of cyclic olefins under nitrogen and hydrogen atmospheres was much higher than conventional hydroaromatic donors when no aromatic acceptor was present; (8) Reactivity of hydrogen donors was dependent upon the reactivity of the acceptor as well as that of the donors; (9) Three-ring hydrogen donors, dihydroanthracene and hexahydroanthracene, were most effective for transferring hydrogen to the Argonne coals while octahydroanthracene was the least reactive; (10) The kinetics data obtained for thermal and catalytic reactions involving cyclic olefins and hydroaromatic donors were adequately modeled by pseudo-first order kinetics; and (11) {Delta}G values calculated for cyclic olefins and hydroaromatic donors based on kinetics data adequately represented the reactivity observed experimentally.
Date: December 31, 1993
Creator: Curtis, C. W.
Partner: UNT Libraries Government Documents Department

Improved performance in coprocessing through fundamental and mechanistic studies in hydrogen transfer and catalysis. Quarterly report, December 26, 1989--March 26, 1990

Description: To gain a fundamental understanding of the role and importance of hydrogen transfer reactions in thermal and catalytic coprocessing by examining possible hydrogen donation from cycloalkane/aromatic systems and by understanding the chemistry and enhanced reactivity of hydrotreated residuum, as well as by enriching petroleum solvent with potent new donors, nonaromatic hydroaromatics, thereby promoting hydrogen transfer reactions in coprocessing. The detailed results of experiments performed on several subtasks during the quarter are presented.
Date: December 31, 1990
Creator: Curtis, C. W.
Partner: UNT Libraries Government Documents Department