Structural investigations of Eocene coals from foreland basin of central Nepal Himalaya

Cheng Huang,Pk Singh,Bhupati Neupane,Yiwen Ju,Bishow Raj Silwal

doi:10.1177/0144598717716283

Abstract

Structural investigations of Eocene coal from foreland basin of central Nepal Himalaya were subjected to attenuated total reflection Fourier transform infrared spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and scanning electron microscopy to study their chemical and structural characteristics. The attenuated total reflection Fourier transform infrared spectroscopy data show that the less matured coal sample (sub-bituminous) has more aliphatic moieties, whereas the relatively more matured (bituminous) coal samples contain higher fractions of poly-aromatic moieties and saturated long-chain hydrocarbons. Fourier transform infrared spectroscopy spectra reveals the presence of stretching vibrations of aliphatic –CH, –CH2 and –CH3 absorptions, –OH bonds, C=C and –CH of aromatic structures and C=O stretching vibrations of carbonyl groups. X-ray diffraction indicates the presence of crystalline carbon having turbostratic structure along with some highly disordered amorphous car...

Highlights

The heterogeneity of coal, consisting of macerals and minerals, reflects varied depositional environment and the nature of the organic precursors (Gupta, 2007; Singh et al, 2013a, 2013b)
Based on the vitrinite random reflectance (VRr) varying from 0.44% to 0.62%, these coals are sub-bituminous to bituminous-C in rank
Various analytical techniques were applied to study the structural investigations of Eocene coal from the foreland basin of central Nepal Himalaya

Summary

Introduction

The heterogeneity of coal, consisting of macerals and minerals, reflects varied depositional environment and the nature of the organic precursors (Gupta, 2007; Singh et al, 2013a, 2013b). FTIR spectroscopy is extensively used for the study of molecular structures of coal (Painter et al, 2012; Solomon and Carangelo, 1982, 1988) and provides important information on the function of organic compounds (Orrego-Ruiz et al, 2011) It helps in assigning the particular bands to various functional groups (Li et al, 2007; Painter et al, 2012; Solomon and Carangelo, 1988; Stuart, 2005) such as the aromatic or aliphatic nature of a CH bond as well as an organic or inorganic nature of a hydroxyl (OH) bond (Singh et al, 2015b). HR-TEM and SEM are widely accepted techniques for the characterization of carbon nanomaterials, including nanoballs and nanotubes, and help in understanding the surface microstructures in coal (Aqel et al, 2012; Dosodia et al, 2009; Pan et al, 2016; Qiu et al, 2002; Tian et al, 2004; Velasco-Santos et al, 2003; Wang et al, 2006; Zelenskii et al, 2012)

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