FT-IR investigation of the structural changes of Sulcis and South Africa coals under progressive heating in vacuum

Two samples of coals coming from South Africa and Sulcis (Sardinia, Italy) were subjected to progressive heating up to 800 degrees C in vacuum. The infrared (IR) spectra of the residuals obtained at 100 degrees C intervals from room temperature to 800 degrees C show spectral changes ascribed to transformations at the level of the organic and inorganic components. Comparing these results with those previously obtained by heating the same coals in the presence of air and examining their pyridinic extracts, it appears that the Sulcis coal with respect to the other coals contains a lower amount of clay-minerals. Furthermore, the IR analysis shows that this coal is nearer to bring a lignite than a hard-coal. (C) 2000 Elsevier Science Ltd. All rights reserved.