Sharma, Raj Vardhan and Kumar, Santosh and Adak, Ashis K and Maity, Sudip (2024) A comparative study of molecular structure and combustion behavior of coal and its separated vitrains. Journal of Molecular Structure, 1299.

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Abstract

A systematic study has been conducted on two coking coals and their separated vitrains to understand the macromolecular structure and their thermal behavior. The structural parameters have been determined by using XRD (X-ray diffraction), Raman spectroscopy, FTIR, Solid-state 13C NMR and TG/DTG–DSC. The proximate and ultimate analyses results indicate that vitrinite is the major organic component of coal and it is type III kerogen having H/C ratio in the range of 0.58–0.72 and O/C ratio in the range of 0.09 to 0.16. The inter-layer spacings, crystallite size, the average number of the aromatic layers, aromaticity, and rank of demineralized coal and vitrain as obtained from XRD studies vary in the range of 3.49–3.70 Å, 13.24–16.72 Å, 3.60–4.74, 0.72–0.80 and 2.62–3.98 respectively. The values of aromaticity, rank and inter-layer spacing of vitrain are higher however the crystallite size and the average number of the aromatic layer are lower than that of respective demineralized coal. Raman spectra results show that vitrain is more graphitic and stable in nature compared to their bulk coal and the structure of coal gets disordered during demineralization. The FTIR spectrum shows that carboxylic (–COOH), carbon–Carbon double bonds (–Cdouble bondC–), carbonyl/carboxyl (Cdouble bondO), methyl and methylene (–CH3, –CH2–), and a hydroxyl group (-OH) are the major functional groups. The structural parameters as obtained from FTIR studies such as aromaticity (fa)FTIR, degree of condensation of aromatic rings and aliphatic to aromatic ratio are higher in vitrain than their respective coals, while the aliphatic hydrogen to total hydrogen ratio (Hal/H) of demineralized coal is higher than the raw coal and vitrain. The 13C NMR spectra show the fraction of unsaturated carbon is higher in vitrain than the respective raw coal. The thermal analysis result shows the reactivity of the samples increases in the order of demineralized coal > vitrain > raw coal and the activation energy increases in the order of raw coal > demineralized coal > vitrain.

Item Type:	Article
Subjects:	Enviornmental Management Coal Gesification
Divisions:	UNSPECIFIED
Depositing User:	Mr. B. R. Panduranga
Date Deposited:	24 Jan 2024 06:46
Last Modified:	24 Jan 2024 06:46
URI:	http://cimfr.csircentral.net/id/eprint/2665

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