Mazumdar, Bhupendra Kumar (1988) Aromacity of coal - a reappraisal of the graphical densimetric approach. Fuel Processing Technology, 19 (2). pp. 179-202. ISSN 0378-3820

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A reappraisal of the graphical-densimetric approach has clearly indicated that values of aromaticity (fa) originally derived thereof, are in reality about 10–15% higher, especially in the lower rank coals (C: 70.5 to 81.5%), for several reasons e.g., (i) omission of a correction to atomic H/C ratio for some oxygenated groups, (ii) imprecise volume correction made to Mc/d on account of heteroatoms in coal (particularly of oxygen groups) and (iii) more seriously, due to omission of a correction for non-aromatic CH groupings such as CH2, CH and CH3 groups. Justification for the above corrections, in particular for No. (iii), is provided by suitable studies on a series of model compounds which include naphthalene, tetralin, decalin, coronene and hydrocoronenes. Furthermore, an equation correlating fa with H/C and Mc/d has been developed which has been found to be more reliable and accurate than the graphical method for the estimation of aromaticity of coal provided the corrections, as hereinbefore stated, are duly applied. The equation in its general form is as follows: fa = [1 − (H/C)corr] + X[ (Mc/d)corr − 5.34], where the value of factor X varies from 0.115 to 0.125 depending on the nature of organic compounds and complexes. Generally for coal with atomic H/C ratio being ⩾0.70, X is 0.115 and if H/C <0.70, the factor to be employed should be 0.125. The applicability and accuracy of the correlation have been studied in respect of many organic compounds and a series of coal models, and it is observed that calculated values match the theoretical values to within 1%. Finally, a revaluation of the estimates of fa of a series of vitrinites, originally derived from the graphical-densimetric approach, is presented. Such values are found to be about 5 to 12 units lower than the previous estimates for lignites and bituminous coals (C: 70.5 to 89.0%), whereas there was virtually no change in the values for semi-anthracites and anthracites, as expected from the revaluation. In view of the sounder basis presently provided in this paper for the densimetric approach, it appears that we may have a definitive set of aromaticity values for coal.

Item Type: Article
Subjects: Physical Properties
Divisions: Director�s Secretariat
Depositing User: Bidhan Chaudhuri
Date Deposited: 25 Nov 2013 12:04
Last Modified: 18 Mar 2016 17:45

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