Raman characterization of coal chars obtained in a pressurized bed reactor

The aim of this work was to evaluate the effect of pressure on the structural properties and subsequent reactivity of coal chars. Pyrolysis reactions were carried out in a fixed bed reactor at 800 oC, by varying the pressure from 1 to 20 atm. Two coal samples with a substantial difference in the swelling index were used for the analysis. Structural analysis of the coal chars was performed using Raman microscopy, this characterization was intended to figure out differences in the carbonaceous structures after the pressurized pyrolysis. The coal chars characterization was complemented by MEB micrographs and reactivity with molecular oxygen in TGA. Characteristic Raman bands showed significant changes for the pressurized condition without clear differences due to pressure changes. The pyrolysis pressure affected the ordering of the carbonaceous structures during pyrolysis, and this effect was less significant in the coal with softening properties.