• Login
    View Item 
    •   NWU-IR Home
    • Research Output
    • Faculty of Engineering
    • View Item
    •   NWU-IR Home
    • Research Output
    • Faculty of Engineering
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Chemical–structural properties of South African bituminous coals: insights from wide angle XRD–carbon fraction analysis, ATR–FTIR, solid state 13C NMR, and HRTEM techniques

    Thumbnail
    Date
    2015
    Author
    Okolo, Gregory N.
    Neomagus, Hein W.J.P.
    Everson, Raymond C.
    Roberts, Mokone J.
    Bunt, John R.
    Metadata
    Show full item record
    Abstract
    The chemical–structural properties of four South African bituminous coals were investigated using wide angle X-ray diffraction–carbon fraction analysis (WAXRD–CFA), attenuated total reflection Fourier transform infra-red spectroscopy (ATR–FTIR), solid state 13C nuclear magnetic resonance spectroscopy (ss 13C NMR), and high resolution transmission electron microscopy (HRTEM). The aromaticity of the samples determined by solid state 13C NMR ranged from 0.74 to 0.87 and compared well with the WAXRD–CFA results (0.73–0.86). WAXRD–CFA, ATR–FTIR and 13C NMR data showed that the lower iso-rank coal samples contained more aliphatic moieties; while the higher rank sample contained higher fractions of polyaromatic moieties and saturated long chain hydrocarbons. The lattice parameters determined from WAXRD–CFA show that lower rank coals investigated are structurally less well-ordered than the higher rank coal. Also, its fringes were quantified as having the greatest preferential alignment of the coals examined. HRTEM aromatic fringe image analysis revealed that the carbon lattice of the samples consist of aromatic fringes of varying lengths, L (3 Å ⩽ L ⩽ 95 Å), which corresponded to a molecular weight distribution ranging from 75 to 1925 amu, assuming circular catenation. The coal with the highest volatile matter yield was found to exhibit a higher frequency of lower molecular weight fringes; while the higher rank coal possessed the most higher molecular weight fringes. The average molecular weights determined for the samples from 13C NMR varied between 504 and 544 amu; and compared well with the values from HRTEM aromatic fringe image analysis data. Thus, there was good agreement and consistency between the different techniques. It was demonstrated that, for the characterisation methods used in this study; that vitrinite reflectance impacts more on the chemical–structural properties of these coals than maceral composition does
    URI
    http://hdl.handle.net/10394/18255
    https://www.sciencedirect.com/science/article/pii/S0016236115006079
    https://doi.org/10.1016/j.fuel.2015.06.027
    Collections
    • Faculty of Engineering [1136]

    Copyright © North-West University
    Contact Us | Send Feedback
    Theme by 
    Atmire NV
     

     

    Browse

    All of NWU-IR Communities & CollectionsBy Issue DateAuthorsTitlesSubjectsAdvisor/SupervisorThesis TypeThis CollectionBy Issue DateAuthorsTitlesSubjectsAdvisor/SupervisorThesis Type

    My Account

    LoginRegister

    Copyright © North-West University
    Contact Us | Send Feedback
    Theme by 
    Atmire NV