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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

Effect of tetralin on polymer degradation in solution. [Quarterly report, January--March 1995]

Description: The effect of a hydrogen-donor solvent (tetralin) on the thermal degradation of poly(styrene-allyl alcohol) in solution was investigated in a steady-state tubular flow reactor at 1000 psig (6.8 MPa), at various tetralin concentrations (0--50%), polymer concentrations (1--4 g/L), and temperatures (130--200 C). The molecular weight distributions of the effluent at each condition were examined as a function of residence time by gel permeation chromatography. In the presence of tetralin, the polymer degrades by deploymerization to specific low molecular weight compounds and by random chain scission. No reaction was observed in the solvent 1-butanol in the absence of tetralin. The experimental data were interpreted with a rate expression first-order in polymer concentration based on continuous mixture kinetics, and rate coefficients were determined for the specific and random degradation processes. Activation energies were in the range of 5--10 kcal/mol for specific degradation and 33 kcal/mol for the random degradation process. A plot of rate coefficients versus tetralin concentration indicates a first-order rate at low tetralin concentrations and a zero-order dependence at high tetralin concentrations.
Date: April 26, 1995
Creator: Madras, G.; Smith, J.M. & McCoy, B.J.
Partner: UNT Libraries Government Documents Department

Mechanism of hydrogen incorporation in coal liquefaction. Quarterly progress report, April 1995--June 1995

Description: Mechanisms important to coal liquefaction and hydrogen transfer in coal liquefaction are being investigated. We continued our studies of the reactions of various organic compounds with D{sub 2}. Also described in this report is the success of hydrogenating naphthalene utilizing silica as a catalyst.
Date: September 1, 1995
Partner: UNT Libraries Government Documents Department

Role of aromatic structure in pathways of hydrogen transfer and bond cleavage in coal liquefaction: Theoretical studies

Description: The mechanisms by which strong carbon-carbon bonds between aromatic rings and side chains are cleaved under hydropyrolysis conditions remain a subject of wide interest to fuel science. Recently, the authors have studied in detail an alternate pathway for hydrogen atom transfer to {pi}-systems, radical hydrogen transfer (RHT). RHT is the direct, bimolecular transfer of hydrogen from the {beta}-position of an organic radical to the target {pi}-system. In the initial theoretical study, they examined the reaction ethyl radical + ethylene = ethylene + ethyl at the spin-projected UMP2/6-31G** level of theory. Recently, they have used a calibrated ROHF-MNDO-PM3 method to predict thermoneutral RHT barriers for hydrogen transfer between hydroaryl radicals and the corresponding arene. Because of the inherent limitations of semiempirical methods such as ROHF-MNDO-PM3, they have extended the initial work with the ethyl + ethylene study to examine this reaction at the ROHF-MBPT[2]-6-31G** and ROHF-CCSD[T]-6-31G** levels of ab initio theory. The primary objective was to determine how intrinsic RHT barriers change with conjugative stabilization of the radicals. The spin-restricted ROHF approach has been applied to study several RHT reactions, and they present completed ROHF results for the ethyl + ethylene system and preliminary results for the methallyl + butadiene system. The methallyl + butadiene system serves as a model for highly stabilized hydroaryl radicals: the methallyl radical exhibits a C-H bond strength of 46.5 kcal/mol compared to 9-hydroanthracenyl, 43.1 kcal/mol.
Date: September 1, 1995
Creator: Franz, J.A.; Autrey, T.; Camaioni, D.M.; Watts, J.D. & Bartlett, R.J.
Partner: UNT Libraries Government Documents Department

Intermolecula transfer and elimination of molecular hydrogen in thermal reactions of unsaturated organic compounds

Description: Two reactions which are important to coal liquefaction include intermolecular transfer and the elimination of two hydrogen atoms. We have designed several model reactions to probe the viability of several hydrogen transfer and elimination pathways. This report described studies on these reactions using organic model compounds.
Date: February 10, 1995
Creator: Suria, S.
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

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

Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, January--March 1995

Description: The research performed during the quarter, January to March 1995, focused on two areas. The first area involved completing the writing of a manuscript based on research performed on this project concerning the mild acidic pretreatment of low rank coals and their liquefaction behavior in the presence of hydrogen donors with different reactivities. The manuscript was submitted for review to Energy and Fuels. A second manuscript was begun which discussed the research involving the hydrogen donation at low severity condition by hexahydroanthracene. The catalytic enhancement of hydrogen transfer by cyclic olefins was also examined. The data from this research was reexamined; it was decided that before writing the paper than the data should be reanalyzed. Therefore, this quarter was spent taking the raw data and reanalyzing the data, putting the solvent fractionation data on a solvent-free basis. The recalculated data and the calculational method is given as Part 1 in this report. The second area that was worked on this quarter was the high temperature infrared analysis of cyclic olefins. The work is ongoing and is currently involving a considerable amount of equipment and technique development. Part 2 is the discussion on the high temperature infrared analysis of cyclic olefins.
Date: September 1, 1995
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

Rate inhibition of steam gasification by adsorbed hydrogen. Technical progress report, October 1--December 31, 1995

Description: Efforts during the ninth quarter of the grant period have focused on completing core matrix experiments and initiating experiments with coal char in addition to Saran char. Experimental progress was delayed somewhat during this quarter, as the turbomolecular pump on the mass spectrometer vacuum system malfunctioned and had to be replaced. That resulted in a one-month shutdown of the apparatus. During that time, progress was made on preparation of theses, manuscripts for publication, and proposals for future funding. New results this quarter include reactions to intermediate levels of conversion (20--30%) and correction of hydrogen content for char aging in several samples. The authors can now state conclusively that surface hydrogen concentration following gasification exclusively depends only conversion and not on gasification conditions such as gas composition or pressure. Surface hydrogen concentration initially increases very rapidly to about 10 cm{sup 3}/g at 1% carbon conversion, and then slowly increases out to 90 cm{sup 3}/g at 70% conversion, the highest levels they have measured. Initial results of gasification with unannealed and annealed coal char are given; results for unannealed and annealed Saran char are also given for comparison.
Date: June 1, 1996
Creator: Miller, D.J.
Partner: UNT Libraries Government Documents Department

Supercritical catalysts of light hydrocarbon conversion. DOE PETC eighth quartery report, July 1, 1995--September 30, 1995

Description: The solid superacid catalysts investigated in this project catalyze hydrocarbon conversions by routes involving carbocation intermediates. This report is a summary of mechanisms of hydrocarbon conversion catalyzed by these and related solid acids. This mechanistic information summarized here is important to the present project because it provides guidance for the modeling of the kinetics of the catalytic butane conversion and propane conversion. Because of the difficulty of determining surface reaction intermediates, understanding of surface reaction mechanisms lags far behind that of solution reaction mechanisms, and what is known about the former is fragmentary and often largely based on presumed analogies with the latter, combined with results such as those from tracer experiments, kinetics experiments, and theoretical chemistry.
Date: June 1, 1996
Creator: Gates, B.C.
Partner: UNT Libraries Government Documents Department

Mild acidic pretreatment to enhance low severity coal liquefaction promoted by cyclic olefins. Quarterly report, July 1995--September 1995

Description: Research continued on low severity coal liquefaction. Research using high temperature infrared of cyclic olefins progressed well during this quarter. Several fluorinated solvents were found that provide a high temperature medium for isotetralin and its aromatic and aliphatic analogues.
Date: March 1, 1996
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

The mechanism of hydrogen incorporation in coal liquefaction. Final report

Description: The purpose of the research was to determine the detailed molecular mechanism for the introduction of hydrogen into coal when it is heated in an atmosphere of H{sub 2} in the absence of catalysts and to use this information as a baseline for the study of catalyzed processes. The plan was to study the reaction of model compounds with D{sub 2} in a glass-lined reactor of the authors` design and, by determining the distribution of D atoms in the reaction products, to deduce the reaction mechanism(s). As of the date of this report (Nov. 1995), the authors have, they believe conclusively, demonstrated the mechanism of the thermal process. They have studied several gas-phase reactions and, recently, have extended these to surface-immobilized models. The data are consistent in their support of the proposed sequence. Within the past year, they have begun to look at catalyzed hydrothermolysis and, while the work is at an early stage, they can draw a few significant conclusions, presented in the report.
Date: November 1, 1995
Partner: UNT Libraries Government Documents Department

Short contact time direct coal liquefaction using a novel batch reactor. Quarterly report, May 15, 1995--September 15, 1995

Description: The objective of this research is to optimize the design and operation of the bench scale batch reactor for coal liquefaction at short contact times (0.01 to 10 minutes or longer). Additional objectives are to study the kinetics of direct coal liquefaction, particularly at short reaction times, and to investigate the role of the organic oxygen components of coal and their reaction pathways during liquefaction. This quarterly report covers the status of progress toward these objectives. 3 refs., 14 figs., 2 tabs.
Date: October 5, 1995
Creator: Klein, M.T.; Calkins, W.H. & Huang, He
Partner: UNT Libraries Government Documents Department

Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, April--June, 1995

Description: The goal of this research is to develop a methodology for analyzing the reactivity of cyclic alkenes in situ in a high temperature and high pressure infrared cell. Cyclic alkenes are highly reactive donors of hydrogen to coal in low severity coal liquefaction.
Date: January 1, 1996
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

Role of the resid solvent in catalytic coprocessing with finely divided catalysts. Final report

Description: The role of the resid in coprocessing coal with petroleum resid has been investigated using model systems. The primary question being investigated is whether resid is participating in reactions with coal or if the resid is acting simply as a diluent. Since hydrogen transfer is an important mechanism by which solvent interacts with coal, hydrogen transfer between naphthenes, saturated alicyclic molecules, that represent resid and aromatic molecules that represent coal were examined in reactions with a high pressure H{sub 2} atmosphere that is typical of actual coprocessing. The model naphthene, perhydropyrene, was chosen as the donor species and the models, anthracene, phenanthrene, and benzophenone, were chosen as the acceptor species. Coprocessing reactions of coal with petroleum resid were performed to evaluate the effect of the chemistry of both constituents on coal conversion and the upgrading of the heavy resid. Three heavy resids, Maya, FHC-623 and Manji were used as the whole resid and as fractions that has been separates into hexane solubles and saturate fractions.
Date: January 1, 1996
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

Effect of tetralin on the degradation of polymer in solution

Description: The effect of a hydrogen-donor solvent tetralin on thermal degradation of poly(styrene-allyl alcohol) in liquid solution was investigated in a steady-state tubular flow reactor at 1000 psig at various tetralin concentrations, polymer concentrations, and temperatures. The experimental data were interpreted with continuous- mixture kinetics, and rate coefficients determined for the specific and random degradation processes.
Date: December 31, 1995
Creator: Madras, G.; Smith, J.M. & McCoy, B.J.
Partner: UNT Libraries Government Documents Department

A unified view of coherent and incoherent dihydrogen exchange in transition metal hydrides by nuclear resonance and inelastic neutron scattering

Description: In this paper a unified view of coherent and incoherent dihydrogen exchange in transition metal hydrides by nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) is presented. It is shown that both exchange processes coexist i.e. do not transform into each other although they may dominate the spectra in different temperature ranges. This superposition is the consequence of the incorporation of the tunnel frequency J of the coherent process into the nuclear two-spin hamiltonian of hydrogen pairs which allows to treat the problem using the well known density matrix theory of NMR line-shapes developed by Alexander and Binsch. It is shown that this theory can also be used to predict the line-shapes of the rotational tunneling transitions observed in the INS spectra of transition metal dihydrogen complexes and that both NMR and INS spectra depend on similar parameters.
Date: August 12, 1995
Creator: Limbach, H.H.; Ulrich, S.; Buntkowsky, G.; Sabo-Etienne, S.; Chaudret, B.; Kubas, G.J. et al.
Partner: UNT Libraries Government Documents Department

Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1995--December 1995

Description: The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive donor compounds that readily donate their hydrogen to coal and model acceptors when heated to temperatures of 200{degrees}C and above. These donors are active donors in the low severity liquefaction of coal at 350{degrees}C as shown in the research performed in this project. The infrared studies are being performed in a high temperature infrared cell that was obtained from AABSPEC. Modifications to that cell have been made and have been reported in previous progress reports. During this last quarter the useful temperature range of the high temperature infrared cell was extended to 230{degrees}C through the use of a high-boiling perfluorocarbon solvent. The solvent used was an Air Products and Chemicals Company proprietary product trade named Multifluor APF-240. Solubilities of aromatics and cyclic olefins were quite low in APF-240, usually less than 0.1 wt% at room temperature, but were found to be a strong function of temperature, increasing markedly when the mixtures were heated to 65{degrees}C. Spectra have been obtained of n-hexadecane and naphthalene at temperatures of 65, 100, 125, 150, 175, 200 and 230{degrees}C. This demonstration of the safe operation of the high temperature IR cell and the acquisition of spectra at elevated temperatures paves the way for kinetic studies of the hydrogen donor capability of isotetralin. A perfluoroether has been obtained from Dupont which should extend the useful temperature range of the high temperature IR cell to 350{degrees}C.
Date: December 31, 1995
Creator: Curtis, C.W.
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

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

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

DOE Laboratory Catalysis Research Symposium - Abstracts

Description: The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.
Date: February 1, 1999
Creator: Dunham, T.
Partner: UNT Libraries Government Documents Department

Low severity coal liquefaction promoted by cyclic olefins. Quarterly technical progress report, April--June 1996

Description: The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive donor compounds that readily donate their hydrogen to coal and model acceptors when heated to temperatures of 200{degrees}C and above. These donors are active donors in the low severity liquefaction of coal at 350{degrees}C as shown in the research performed in this project. The infrared studies are being performed in a high temperature infrared cell that was obtained from AABSPEC. Modifications to that cell have been made and have been reported in previous progress reports.
Date: December 31, 1997
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, July--September 1996

Description: The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive donor compounds that readily donate their hydrogen to coal and model acceptors when heated to temperatures of 200 C and above. These donors are active donors in the low severity liquefaction of coal at 350 C as shown in the research performed in this project. The infrared studies are being performed in a high temperature infrared cell that was obtained from AABSPEC. Modifications to that cell have been made and have been reported in previous progress reports. The useful temperature range of the high temperature infrared cell has been extended to 230 C through the use of a high-boiling perfluorocarbon solvent. High temperature infrared analyses have been performed using isotetralin, tetralin, naphthalene, 1,4-dihydronaphthalene and 1,2-dihydronaphthalene. Stability studies have shown that naphthalene was quite stable at temperatures up to 230 C, as were tetralin, decalin and 1,4-dihydronaphthalene. High temperature FTIR analysis of isotetralin and 1,2-dihydronaphthalene reacted at elevated temperatures forming tetralin and 1,4-dihydronaphthalene, respectively. The results of stability studies are reported.
Date: May 1, 1997
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department