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Rafael Kandiyoti - One of the best experts on this subject based on the ideXlab platform.

  • structural features of large molecular mass material in coal derived liquids catalytic hydrocracking of the pyridine insoluble fraction of a coal tar Pitch
    European Journal of Mass Spectrometry, 2000
    Co-Authors: V Begon, C A Islas, Denis R. Dugwell, María J. Lázaro, Isabel Suelves, Alan A. Herod, Rafael Kandiyoti
    Abstract:

    The pyridine-insoluble fraction of a Coal-Tar Pitch has been catalytically hydrocracked. The starting sample contained no material that could be observed by gas chromatography/mass spectrometry (GC/MS) or by heated-probe mass spectrometry. The aim of the study was to generate structural information on this narrow cut of large-molecular-mass material, which consisted mainly of compounds boiling above 450°C. A much broader boiling-point distribution was found for hydrocracked products; evidence from all analytical techniques used (size-exclusion chromatography, UV-fluorescence spectroscopy and heated-probe mass spectrometry) indicated a significant reduction of the molecular mass range. A wide variety of aromatic groups was identified in hydrocracked products by heated-probe mass spectrometry, ranging from phenanthrene (m/z 178) to beyond dibenzocoronene (m/z 400). Ions corresponding to alkyl (m/z 43, 57, 71 and 85) and alkenyl groups (m/z 41, 55, 69 and 83) were detected. The results reflect the ability of the hydrocracking process to cleave bonds within large Pitch molecules, releasing the structural units which form the molecules. The structure of the original pyridine-insoluble material may thus be seen as a series of aromatic groups linked by short bridges or small groups, but with some longer aliphatic bridges (C12 and C17) as shown by pyrolysis-GC/MS. Clearly, some molecular species were reduced in mass but still lay above the range of detection by heated-probe mass spectrometry and could not be identified. Although the extent to which large polycyclic aromatic entities themselves have been cracked (or otherwise reduced to smaller polycyclic aromatic groups) cannot be quantitatively discerned from the present data, the hydrocracking of isolated fractions of intractable coalderived material appears to offer a useful method for probing their structural features.

  • comparison of the fractionation of a coal tar Pitch by solvent solubility and by planar chromatography
    Fuel, 1999
    Co-Authors: María J. Lázaro, Alan A. Herod, Rafael Kandiyoti
    Abstract:

    Abstract Two methods of fractionation of a coal tar Pitch, one based on solvent solubility separation and the other on preparative thin layer chromatography were compared for effectiveness of the separation. The fractions were characterised using size exclusion chromatography (SEC) and UV-fluorescence spectroscopy (UV-F). Fractionation by planar chromatography was found to give a better separation and to use less solvent than the solvent separation method. Both SEC and UV-F clearly showed less overlap in fractions separated by planar chromatography, compared to solvent fractionation. The cleaner separation of the heaviest fraction is particularly relevant for the mass spectroscopic investigation of large molecular mass materials, where the presence of lighter materials was observed to suppress high-mass signal. The close agreement observed between SEC and UV-F is consistent with previously reported correlations for coal tar Pitches. However, the relevant SEC work was performed using pyridine as the mobile phase. We have found that 10%–15% of coal tar Pitches cannot be dissolved in pyridine whilst total dissolution of coal tar Pitch may be achieved using NMP. The calibration of analytical columns operated with NMP would be expected to lead to more accurate evaluations of molecular masses in these complex mixtures.

  • fractionation by planar chromatography of a coal tar Pitch for characterisation by size exclusion chromatography uv fluorescence and direct probe mass spectrometry
    Journal of Chromatography A, 1995
    Co-Authors: Alan A. Herod, Rafael Kandiyoti
    Abstract:

    Abstract A coal tar Pitch, extensively studied by other techniques, has been fractionated by planar chromatography using successive development in tetrahydrofuran, chloroform-methanol (4:1, v/v), toluene and pentane. Pitch fractions were distinguished by relative retention. The fractions were characterised in solution by size-exclusion chromatography, UV-fluorescence emission spectroscopy and as the solid on silica, by direct solid-probe mass spectrometry. The method has led to structural information not readily available by direct characterisation of the original mixture itself: (i) A progressive shift of UV-fluorescence spectral maximum intensity and molecular mass with decreasing mobility of the fractions on the planar chromatographic plate, suggesting progressively larger polynuclear aromatic systems; (ii) Nitrogen containing species in the Pitch separated from the polynuclear aromatic hydrocarbons which form the bulk of the sample. Neutral and basic nitrogen fractions were defined relative to standards and molecular mass numbers in probe mass spectrometry; (iii) Mass ranges of nitrogen components in these fractions exceed those found previously by GC-MS of the total Pitch or its fractions. (iv) Size-exclusion chromatography of the fractions suggests that polar materials are not simply separated by size.

Yao Run-sheng - One of the best experts on this subject based on the ideXlab platform.

  • Advance in the Research of Coal-Tar Pitch Fuel
    Boiler Technology, 2020
    Co-Authors: Yao Run-sheng
    Abstract:

    Coal tar Pitch is the staple product in processing tar,it,s yield counts for 50%~60% of tar.Along with the enhance of the demand of environment protection,conflangating coal tar Pitch directly was restritecl,it becames a very important problem that how to increase the extra value of coal tar Pitch by disposiny it more deeply,coal tar Pitch slurry fuek is a effective approach for solving this problem.In this paper,Coal-Tar Pitch slurry fuel has been introduced on the bases of Pitch slurry fuel.The prepare principle of Coal-Tar Pitch fuel and the research advance of two fuel: coal bitumen emulsion fuel and coal Pitch-water slurry have also been introduced.At preseat,the report of coal tar Pitch slurry fuel is singularly,therefore,it,s recessary to inhance the research and development of this product.

  • The Study and Application of Coal-Tar Pitch Fuel
    Clean Coal Technology, 2020
    Co-Authors: Chang Hong-hong, Yao Run-sheng
    Abstract:

    In this paper the actuality of Coal-Tar Pitch resource as well as it's application in the field fuel were ana- lyzed,meanwhile the foreground of developing Coal-Tar Pitch fuel were forecasted.It is very important to machining Coal-Tar Pitch in order to increase it's additional-value and the preparation of fuel oil by Coal-Tar Pitch will be one of the approach of it.

  • Study on preparation process of medium temperature Coal-Tar Pitch powder
    Modern Chemical Industry, 2020
    Co-Authors: Yao Run-sheng
    Abstract:

    The process to prepare Coal-Tar Pitch powder with medium-temperature Coal-Tar Pitch as raw material is studied,and the Coal-Tar Pitch powder with granularity of 200 mesh or less is obtained via freezing grind and surfactant adding.The product is stable at room temperature.The influencing factors on stability and caloric value of Coal-Tar Pitch powder,such as raw material freezing temperature,pulverization time,storing period and temperature,and surfactants,etc.,are also studied.

Frans J. Jongeneelen - One of the best experts on this subject based on the ideXlab platform.

  • Biological exposure limit for occupational exposure to coal tar Pitch volatiles at cokeovens
    International Archives of Occupational and Environmental Health, 1992
    Co-Authors: Frans J. Jongeneelen
    Abstract:

    Biological monitoring is an efficient tool in the evaluation of exposure to chemical agents. However, the dose-response of adverse health effects using biological exposure indices and biological limit values are rarely available. This paper presents an estimation of the occupational exposure limit value of 1-hydroxypyrene in urine, a biological exposure indicator of polycyclic aromatic hydrocarbons (PAH). A large-scale study of the exposure of cokeoven workers to PAH, in wich both air sampling (benzene soluble matter and individual PAH including benzo( α )pyrene) and biological monitoring (1-hydroxypyrene in urine) were applied, made it possible to establish an empirical mathematical relationship between the air sampling data and biological monitoring data. It was calculated that cokeoven workers with a urinary concentration of 1-hydroxypyrene of 2.3 μmol/mol creatinine after a 3-day working period equals the airborne threshold limit value (TLV) of coal tar Pitch volatiles (CTPV). Epidemiological studies have quantified the relative risk of lung cancer for topside and non-topside cokeoven workers. The published environmental exposure data of topside and non-topside cokeoven workers were used to determine the time-average exposure. The data of 1-hydroxypyrene in the urine of cokeoven workers and data of epidemiological studies from different coke plants were combined according to the concentrations of PAH in the air. Thus, it was possible to establish an indirect relationship between lung cancer mortality risk and the biological exposure indicator for cokeoven workers. Exposure at the level of the suggested tentative biological exposure limit (BEL) of 2.3 μmol/ mol creatinine is estimated to be equal to a relative risk of lung cancer of approximately 1.3.

Bi Ji-cheng - One of the best experts on this subject based on the ideXlab platform.

  • Reactivity of Coal-Tar Pitch in Supercritical Water
    Journal of Taiyuan University of Technology, 2020
    Co-Authors: Bi Ji-cheng
    Abstract:

    Reactivity of Taihua Coal-Tar Pitch in SCW was investigated using a batch reactor.The effects of temperature(400 ～480 ℃),pressure(23.1 ～39.5 MPa) and residence time(1 ～80 min) on the conversion of Taihua coal-tat Pitch were discussed.The composition of product and the content of chemicals were analyzed.The reactivity of Coal-Tar Pitchs obtained from different origin was studied.The results indicate that SCW apparently promoted the decomposition of Taihua Coal-Tar Pitch,the yield of maltene increased and the yield of asphaltene decreased.It is also noticed that asphaltene was the main active component.Temperature appeard to be the most sensitive controlling parameter,while the effects of pressure and time were less significant.The analysis results indicate that the yield of high value chemicals was higher than the content in raw material.Physicochemical properties of Coal-Tar Pitch had a significant effect on the reactivity in SCW.

  • Upgrading of Coal-Tar Pitch in supercritical water
    Journal of Fuel Chemistry and Technology, 2008
    Co-Authors: Rong Zhang, Bi Ji-cheng
    Abstract:

    Conversion of Coal-Tar Pitch in supercritical water (SCW) was researched using a batch reactor. The effects of temperature (400°C–480°C), pressure (25 MPa–40 MPa), and residence time (1 min–80 min) on product composition were investigated. When compared with pyrolysis under N2 atmosphere, the conversion of asphaltene to maltene was enhanced, whereas, the formation of gas and char were restrained in SCW. Moreover the yields of high value chemicals were higher than those obtained via pyrolysis. The results suggest that SCW promotes the decomposition of Coal-Tar Pitch into maltene and enhances the yields of high value chemicals. It is also observed that asphaltene is the main active component and it is converted to maltene, gas, and char in SCW. High temperature promotes the reactions of both asphaltene to light components and the formation of char. The results indicate that temperature appears to be the important parameter for coal tar Pitch conversion, whereas, the effects of pressure and time are less significant.

Klaus Mullen - One of the best experts on this subject based on the ideXlab platform.

  • analyzing solid fossil fuel Pitches by a combination of soxhlet extraction and fourier transform ion cyclotron resonance mass spectrometry
    Carbon, 2020
    Co-Authors: Wen Zhang, Klaus Mullen
    Abstract:

    Abstract Solid fossil-fuel derived Pitches serve as potential feedstocks for the preparation of high-performance carbons materials, which is, however, hampered by the lack of sound knowledge on the molecular composition and structure of Pitches. Soxhlet extraction and ultrahigh-resolution Fourier transform ion cyclotron resonance (FT ICR) mass spectrometry were combined to characterize a petroleum Pitch and a coal tar Pitch, as well as their toluene-soluble and toluene-insoluble fractions. Important information can be gained on the chemical nature of polycyclic aromatic compounds such as pure hydrocarbons or various N-, O- and S-derivatives, as well as the relative abundance of each molecular structure in terms of carbon number vs. hydrogen number. This is the first time that the heteroatom-containing and pure hydrocarbon aromatics were clearly differentiated in such solid Pitch samples. The differences among the toluene-soluble fraction, toluene-insoluble fraction, and unfractionated intact sample of both the petroleum Pitch and coal tar Pitch could be systematically compared at a molecular level. Insight into the molecular structures may provide a rational basis for the use of such carbon-rich materials for the fabrication of nanographenes, organic light-emitting diodes, and carbon fibers.