Title: Investigation into coals of different ranks using FTIR and Raman spectroscopy, X-ray diffraction and thermo-kinetic analyses

Authors: Ayokunle O. Balogun; Farid Sotoudehniakarani; Armando G. McDonald

Addresses: Department of Mechanical Engineering, College of Engineering, Landmark University, P.M.B. 1001, Omuaran, Nigeria ' Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, Idaho 83844-1132, USA ' Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, Idaho 83844-1132, USA

Abstract: Two sub-bituminous (Onyeama mine, Nigeria and Powder River Basin, USA) and one bituminous (CNX Coal Resources, USA) coal samples were subjected to structural and chemical characterisation. The FTIR and Raman spectroscopy, X-ray diffraction and other physico-chemical techniques were deployed for this purpose. The coal ranking and aromaticity were evaluated from specific peaks on the XRD diffractogram. The coal samples were also subjected to thermo-kinetic analysis. The HHV for the coal samples ranged from 26.0 MJ/kg to 33.8 MJ/kg. Relatively, the Nigerian coal demonstrated an exceptionally high surface area, approximately 29.0 m2/g while Wyoming's and Pennsylvania's respectively recorded 0.4 m2/g and 3.9 m2/g. The ratio of band intensities, ID/IG was computed from Raman spectroscopy to be between 0.84 and 0.94 for the coal samples. Furthermore, the kinetics parameters deduced from TGA measurements revealed that thermal decomposition of coal is better modelled as a multi-step reaction mechanism. [Received: August 10, 2019; Accepted: January 13, 2020]

Keywords: sub-bituminous coal; X-ray diffraction; XRD; Raman spectroscopy; kinetics; Fourier transform infra-red; FTIR; thermo-kinetic; thermogravimetric analysis; TGA; activation energy; band intensities; HHV.

DOI: 10.1504/IJOGCT.2021.114070

International Journal of Oil, Gas and Coal Technology, 2021 Vol.26 No.4, pp.453 - 468

Received: 10 Aug 2019
Accepted: 13 Jan 2020

Published online: 22 Mar 2021 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article