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  • 1
    Electronic Resource
    Electronic Resource
    Progresses of coal liquefaction catalysts in Japan (1998)
    Springer
    Catalysis surveys from Japan 2 (1998), S. 17-30 
    Details
    ISSN: 1572-8803
    Keywords: coal liquefaction catalysts ; iron sulfides ; pyrrhotite ; bimetallic molybdenum sulfides ; catalyst recycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Research and development of catalysts and their performances for coal liquefaction are reviewed, enphasizing the contribution of recent 20 years from Japan. A variety of iron based catalysts were extensively examined to define the pyrrhotite as the active species produced in the liquefaction process. Synthetic pyrite, synthesized hydroxy ferric oxide, finely ground pyrite and limonite have been applied in the process development of coal liquefaction. Iron impregnation onto coal particles using waste water was examined also in a continuous-flow reactor. Finer particles were found to reduce significantly the amount of the catalyst to obtain the same oil yield. Usefulness of such catalysts is proved in the continuous operation of a large scale pilot plant. Iron, iron–nickel, and iron–molybdenum sulfides were found to be active catalysts when they are supported on nano-particles of carbon. Catalysts for recovery and repeated use and for selective aromatic ring opening are under current research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019049618725
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  • 2
    Electronic Resource
    Electronic Resource
    Oxygen distribution in the mesophase pitch fibre after oxidative stabilization (1989)
    Springer
    Journal of materials science 24 (1989), S. 389-394 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxygen distribution in the transverse section of 30μm diameter mesophase pitch fibres after oxidative stabilization was measured by using EPMA (electron probe X-ray microanalyser) to clarify the progress of the oxidative reaction and diffusion of the oxidant during the stabilization. Oxygen was distributed in shallow gradients regardless of the stabilization time from the surface to the centre of the mesophase pitch (MP) fibres stabilized at 230° C, suggesting sufficient diffusion of the oxidant to the centre of the fibre at this temperature. In contrast, steeper gradients of distribution were observed in the MP fibres stabilized at 270° C although oxygen up-take of the centre increased steadily with the longer stabilization time to decrease the gradient. Much steeper gradients of the oxygen distribution were observed in the cross-sectioned surface of the fibres stabilized at 300° C for 15 and 30min. The gradient became much steeper with longer stabilization, suggesting some barriers in the deeply oxidized zone which may block the oxygen diffusion. The PVC-10 fibres, whose reactivity was enhanced by blending PVC pitch of 10wt%, showed steeper distributions of oxygen after the stabilization at 270° C comparing to those of the MP fibres stabilized under the same conditions. It showed steeper gradient with the longer stabilization time. In conclusion, stabilization at a lower temperature (230° C) allows relatively rapid diffusion of the oxidant into the centre of the MP fibre during rather slow stabilization but, a higher temperature of stabilization (at 300° C) and/or higher reactivity of the mesophase pitch accelerates the oxidation much more rapidly than the diffusion, providing a blockade zone for the oxygen diffusion near the fibre surface. The extensive oxidation may cross-link three dimensionally the mesophase molecules thus allowing no diffusion of oxygen among the molecules. Such diffusion control tends to provide skin-core structure in the carbonized fibre. It should be noted that fibre thinner than 10μm showed no skin-core structure. Diffusion within 5μm from the surface may be rapid under any conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01107416
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  • 3
    Electronic Resource
    Electronic Resource
    Preparation of anisotropic mesophase pitch by carbonization under vacuum (1986)
    Springer
    Journal of materials science 21 (1986), S. 424-428 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Anisotropic mesophase pitch of high solubility and low melting temperature was prepared from petroleum pitch by carbonizing under vacuum conditions at 430° C for 5 h. The solubility and melting temperature were 55 wt% in quinoline and 270° C respectively, at complete development of anisotropic mesophase pitch. This solubility is much higher than that of mesophase pitch from the same feedstock using refluxing and gas blowing conditions. Yields of the mesophase pitch of complete anisotropic development were 60 wt% under vacuum. The structure of these mesophase pitches were analysed in terms of preparative procedures which create high solubility of a completly anisotropic material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01145504
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  • 4
    Electronic Resource
    Electronic Resource
    Control of molecular orientations in mesophase pitch-based carbon fibre by blending PVC pitch (1989)
    Springer
    Journal of materials science 24 (1989), S. 57-62 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Coal tar-derived mesophase pitch and its blends with PVC pitch in 5 or 10 wt% were spun at temperatures from 340 to 390° C by applying pressurized nitrogen. The parent mesophase pitch and the blended pitch showed an excellent spinnability at temperatures from 360 to 380° C and from 350 to 380° C, respectively, to give a thin pitch fibre of 10μm diameter. The transverse texture of the fibres from the parent mesophase pitch showed the radial orientation regardless of a higher spinning temperature of 390° C. In contrast, those from the blended pitches showed random orientation even at the lower spinning temperature of 350° C. The amounts of the blend extruded by spinning at each temperature under 0.2 kg cm−2 G−1 were always larger than those of the mesophase pitch. It is clarified in the present study that blending PVC pitch can realize stable spinning at lower temperatures, where the molecular orientation in the transverse section of the resultant carbon fibre was controlled through decreasing the viscosity of the whole mesophase pitch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00660932
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  • 5
    Electronic Resource
    Electronic Resource
    A structural study on the stabilization and enhancement of mesophase pitch fibre (1990)
    Springer
    Journal of materials science 25 (1990), S. 76-82 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The components of coal tar-derived mesophase pitch fibre and its blend with polyvinyl chloride (PVC) pitch were studied for chemical changes after the stabilization. Microanalyses, solubility and solid 13C NMR measurements were performed. The temperature was found to be very influential on the progress of the stabilization. At a temperature of 230° C, PVC pitch enchanced the oxygen uptake of both fusible pyridine soluble (PS) and non-fusible pyridine insoluble (PI) fractions in the pure mesophase pitch, so shortening the time required for complete stabilization and raising more rapidly the softening point of the PS fraction. More oxygen-containing functional groups, such as phenolic, ether, carboxylic and carbonyl groups, were formed in both fractions. It is noted that any increase in the aromatic ring size of the PI fraction is rather limited at this temperature. In contrast, stabilization of PVC pitch at a higher temperature of 300° C, accelerated the increase in PI without accelerating oxygen uptake of both fractions. Hence, the softening point of the remaining PS was unchanged or even lowered. An increase of aromatic ring size of the PI component by stabilization was marked at the higher temperature. Suggested stabilization schemes and the role of added PVC pitch in accelerating stabilization are discussed for each of these temperatures taking account of the above results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00544187
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  • 6
    Electronic Resource
    Electronic Resource
    Solubility of heat-resisting polymers in mesophase pitches at their spinning temperatures (1990)
    Springer
    Journal of materials science 25 (1990), S. 4898-4905 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Solubilities of two thermoresisting polymers (polyethylene telephthalatep-hydroxybenzoate, a liquid crystal polymer and polyethylene naphthalate) in mesophase pitches (MP) derived from coal tar (C1) and petroleum residues (P1 and P2) were examined to prepare blended fibre as the better precursor for the high-performance carbon fibre. MP-C1 and MP-P1 of high aromaticity dissolved 5 wt% of both polymers on mixing at 360 °C for 3 h, maintaining 100 vol% anisotropy which the parent mesophase pitches exhibited, although only MP-C1 did so at 340 °C. In a marked contrast, a number of isotropic droplets from both polymers dispersed in MP-P2 after the blending under the same conditions. The blends of MP-C1 with polymers were spinnable at around 370 °C into fibres of 10 to 20 μm diameter although their spinnability was slightly inferior to that of the pitch alone. The blended fibre exhibited slightly higher stabilization reactivity at 270 to 300 °C than that of the parent mesophase pitch fibre. Structural factors of the mesophase pitch which influence their dissolving ability are discussed. Thermal stability of the polymers is also briefly examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129959
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative evaluation of mesophase pitches derived from coal tar and FCC-DO (1990)
    Springer
    Journal of materials science 25 (1990), S. 3484-3492 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Three kinds of mesophase pitches (MPs) derived from FCC-DO (P) and hydrogenated QI free coal tar (QIF) were comparatively evaluated in terms of their spinnability and stabilization reactivity based upon their structural characterizations. MP-P, which is meso-phase pitch from FCC-DO, preserved considerable amount of aliphatic and naphthenic hydrogens to show higher solubility, fusibility and softening temperature of as low as 245 °C in spite of its complete anisotropy. MP-C1 derived from catalytically hydrogenated QIF carried less hydrogen content and smaller molecular weight although its solubility and softening temperature were almost the same to those of MP-P. MP-C2 which was prepared from QIF treated with tetrahydro-quinoline (THQ) showed the least hydrogen content, the lowest solubility and the highest softening temperature of 290 °C. MP-P allowed smooth spinning for much longer time at the temperature from 320 to 350 °C. MP-C1 could be spun at the temperature from 340 to 370 °C, which was much higher than that of MP-P in spite of their similar softening temperatures. MP-C2 showed spinnability at the temperature from 340 to 390 °C, although evolved gases disturbed its smooth spinning at the higher temperature. MP-P showed the highest stabilization reactivity to require the shortest time (120 min) for the sufficient stabilization at 250 °C. Although much longer time of 180 min was necessary for the MP-C1 at 250 °C, a higher temperature of 270 °C accelerated the stabilization reactions to shorten the time to 60 min. MP-C2 showed the least reactivity, requiring 120 min at 270 °C. More aliphatic and naphthenic structure of FCC-DO derived mesophase pitch is related to its superiority as the pitch fibre precursor. The catalytic hydrogenation which can produce naphthenic or aliphatic structure is a better pre-treatment to modify the coal tar as the mesophase pitch precursor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00575374
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  • 8
    Electronic Resource
    Electronic Resource
    Structure and stabilization reactivity of mesophase pitch derived from f c c-decant oils (1991)
    Springer
    Journal of materials science 26 (1991), S. 4836-4844 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Structure and stabilization reactivities of three mesophase pitches (MP-1-3) derived from fluid catalytic cracking (f c c)-decant oils were compared to reveal the structure-reactivity correlation in the stabilization reaction, which is the slowest step of the pitch-based carbon fibre production. Analyses of the toluene soluble fraction in mesophase pitches using 1H-, 13C-nuclear magnetic resonance (NMR), infrared and FD-mass spectroscopy suggested that the most abundant molecules in MP-2 and MP-3, which should have the highest and lowest softening points, respectively, consisted of a 7-ring aromatic skeleton with two phenyl groups, molecular weight 478 and a 10-ring aromatic skeleton with a phenyl and four methyl groups, molecular weight 556, respectively. MP-3 exhibited much more rapid stabilization and oxygen up take than MP-2. The analysis of stabilized fibre with Fourier transform-infrared spectroscopy indicated that the oxidative stabilization consisted of the following three steps: (1) oxygen up take to produce functional groups such as carbonyl, phenolic and ether groups; (2) growth of the aromatic ring; and (3) molecular association through hydrogen bonding. The first step of oxidation occurred at substituent alkyl, naphthenic and isolated aromatic hydrogens in the mesogen molecules regardless of the mesophase pitches. The reactivity of the mesophase pitch appears to be correlated to the number of such groups present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549858
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  • 9
    Electronic Resource
    Electronic Resource
    Binderless moulding of green cokes delivered from solvent refined coal and ethylene tar pitch (1982)
    Springer
    Journal of materials science 17 (1982), S. 525-532 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Green cokes, derived from the co-carbonization of Solvent Refined Coals with ethylene tar pitch, have been moulded into discs without using a binder. Cokes with a range of size of optical texture have been prepared by control of the ratios of the two components of the carbonization blend. The appearance of the discs was assessed by optical and scanning microscopy after calcination to 1200° C. The most acceptable disc was prepared by moulding carbon of a heat treatment temperature (HTT) of 440° C. With cokes of HTT〈 440° C excessive dilation adversely decreased the density of the disc. With cokes of HTT 〉 440° C, dimished cohesion of the coke grains prevented the development of a strong disc on calcination. It is considered that the presence of benzene-soluble (BS) and benzene-insoluble/quinoline-soluble (BI/QS) fractions in the pitch systems contribute to cohesion of coke particles having a HTT of 440° C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00591487
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  • 10
    Electronic Resource
    Electronic Resource
    Optimization of carbonization conditions for needle coke production from a low-sulphur petroleum vacuum residue (1988)
    Springer
    Journal of materials science 23 (1988), S. 298-304 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The optimum carbonization conditions for converting a low-sulphur petroleum vacuum residue in a tube bomb in terms of pressure and temperature into better needle coke of low CTE, with less production of poor bottom coke, were studied by observation of the resultant cokes and sequential analyses of carbonization intermediates by means of solvent fractionation and gas evolution. Carbonization at 460°C under 15 kg cm−2 G produced the best needle coke. The quality of the resultant needle coke was strongly influenced by viscosity changes of the system, the solidification range and gas evolution in the carbonization progress. The first two characteristics reflect the rates of condensation (such as QI formation) and devolatilization of soluble fractions, strongly influencing the growth of anisotropic units. The last characteristic reflects the pyrolytic cracking reaction to define the timing of gas evolution during carbonization, influencing the axial orientation of anisotropic texture as well as the porosity in the resultant coke. Both profiles varied very much, depending on the carbonization temperature. Finally, the formation of a bottom coke of fine mosaic texture is discussed from the viewpoint of the co-carbonization concept.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01174069
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