Advanced Thermally Stable Jet Fuels. Technical Progress Report, November 1992--January 1993 PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 158
Book Description
The pyrolysis of octylbenzene (OB) at various temperatures, 400°C, 425°C and 450°C, has been studied. This work represents a continuous effort in the study of the effects of alkylbenzenes in the high temperature thermal degradation of jet fuels, following up the detailed study of the behavior of four isomers of butylbenzenes (1). There are some general similarities in the reactions of OB and butylbenzenes. For example, both produce a large amount of smaller alkylbenzenes during pyrolysis. Reaction kinetics of OB have been calculated based on the temperature range mentioned above, and the major chemical process in its thermal reactions have been analyzed. As expected, temperature plays the most significant role in the degradation process, as shown in Figure 1. The reaction shows only a moderate rate at 400°C, 8.18 mol% of OB remaining after 16 hours of stressing. At 450°C, however, there is virtually no OB left after 8 hours of stressing. Rough comparison of the yields (wt%) of gaseous, liquid and solid products formed (Figures 2, 3 and 4) shows a uniform change in this temperature range. For example, a steady increase of the yields (wt%) of gas and solid formation can be observed in Figures 2 and 3. Global kinetics of the reaction of octylbenzene have been calculated.
Author: Publisher: ISBN: Category : Languages : en Pages : 158
Book Description
The pyrolysis of octylbenzene (OB) at various temperatures, 400°C, 425°C and 450°C, has been studied. This work represents a continuous effort in the study of the effects of alkylbenzenes in the high temperature thermal degradation of jet fuels, following up the detailed study of the behavior of four isomers of butylbenzenes (1). There are some general similarities in the reactions of OB and butylbenzenes. For example, both produce a large amount of smaller alkylbenzenes during pyrolysis. Reaction kinetics of OB have been calculated based on the temperature range mentioned above, and the major chemical process in its thermal reactions have been analyzed. As expected, temperature plays the most significant role in the degradation process, as shown in Figure 1. The reaction shows only a moderate rate at 400°C, 8.18 mol% of OB remaining after 16 hours of stressing. At 450°C, however, there is virtually no OB left after 8 hours of stressing. Rough comparison of the yields (wt%) of gaseous, liquid and solid products formed (Figures 2, 3 and 4) shows a uniform change in this temperature range. For example, a steady increase of the yields (wt%) of gas and solid formation can be observed in Figures 2 and 3. Global kinetics of the reaction of octylbenzene have been calculated.
Author: Publisher: ISBN: Category : Languages : en Pages : 131
Book Description
The Penn State program in advanced thermally stable coal-based jet fuels has five borad objectives: (1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub-micrometer and miocrometer-sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Pyrolysis of four isomers of butylbenzene was investigated in static microautoclave reactors at 450°C under 0.69 MPa of UHP N2. Thee rates of disappearance of substrates were found to depend upon the bonding energy of C[alpha]-C[beta] bond in the side chain in the initial period of pyrolysis reactions. Possible catalytic effects of metal surfaces on thermal degradation and deposit formation at temperatures>400°C have been studied. Carbon deposition depends on the composition of the metal surfaces, and also depends on the chemical compositions of the reactants. Thermal stressing of JP-8 was conducted in the presence of alumina, carbonaceous deposits recovered from earlier stressing experiments, activated carbon, carbon black, and graphite. The addition of different solid carbons during thermal stressing leads to different reaction mechanisms. 13C NMR spectroscopy, along with 13C-labeling techniques, have been used to examine the thermal stability of a jet fuel sample mixed with 5% benzyl alcohol. Several heterometallic complexes consisting of two transition metals and sulfur in a single molecule were synthesized and tested as precursors of bimetallic dispersed catalysts for liquefaction of a Montana subbituminous and Pittsburgh No. 8 bituminous coals.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Penn State program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. An exploratory study was conducted to investigate the pyrolysis of n-butylbenzene in a flow reactor at atmospheric pressure. A number of similarities to trends previously observed in high-pressure static reactions were identified. The product distribution from pyrolysis of n-tetradecane at 400[degrees]C and 425[degrees]C was investigated. The critical temperatures of a suite of petroleum- and coal-derived jet fuels were measured by a rapidly heating sealed tube method. Work has continued on refining the measurements of deposit growth for stressing mixtures of coal-derived JP-8C with tetradecane. Current work has given emphasis to the initial stages of fuel decomposition and the onset of deposition. Pretreatment of JPTS fuel with PX-21 activated carbon (50 mg of PX-21 in 15 mL JPTS) delayed degradation and prevented carbon deposition during thermal stressing at 425[degrees]C for 5 h in nitrogen and air atmospheres. Clear indications of initial and subsequent deposit formation on different metal surfaces have been identified for thermal stressing of dodecane. Seven additives were tested for their ability to retard decomposition of dodecane at 450[degrees]C under nitrogen. Nuclear magnetic resonance data for Dammar resin indicates that structures proposed in the literature are not entirely correct.
Author: Publisher: ISBN: Category : Languages : en Pages : 80
Book Description
The Penn State program in advancd thermally stable coal-based jet fuels has five broad objectives: (1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding them formation of vcarbonaceous solids; and, (5) assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal.
Author: Publisher: ISBN: Category : Languages : en Pages : 126
Book Description
The Penn State program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Some of our accomplishments and findings are: The product distribution and reaction mechanisms for pyrolysis of alkylcyclohexanes at 450°C have been investigated in detail. In this report we present results of pyrolysis of cyclohexane and a variety of alkylcyclohexanes in nitrogen atmospheres, along with pseudo-first order rate constants, and possible reaction mechanisms for the origin of major pyrolysis products are presented. Addition of PX-21 activated carbon effectively stops the formation of carbonaceous solids on reactor walls during thermal stressing of JPTS. A review of physical and chemical interactions in supercritical fluids has been completed. Work has begun on thermal stability studies of a second generation of fuel additives, 1,2,3,4-tetrahydro-l-naphthol, 9,10-phenanthrenediol, phthalan, and 1,2-benzenedimethanol, and with careful selection of the feedstock, it is possible to achieve 85--95% conversion of coal to liquids, with 40--50% of the dichloromethane-soluble products being naphthalenes. (Further hydrogenation of the naphthalenes should produce the desired highly stable decalins.).
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