Sorption of carbon dioxide on the lithotypes of low rank coal

The aims of this work were (1) the determination of the efficiency of isolating by hand two lithotypes concentrates, vitrain and durain, from original coal sample of low rank bituminous coal, (2) the evaluation of the relation between macro- and microscopically distinguishable components of samples under investigation and their physicochemical properties and (3) the assessment of the effect of maceral composition of low rank coal on carbon dioxide sorption capacity and desorption process. To address the first issue a petrographic analysis was performed for separated components and the original raw sample. A significantly higher vitrinite content in vitrain concentrate and much lower in durain concentrate in regard to basic coal confirmed that the separation process was satisfactory. The second aspect comprised an investigation into selected physical and chemical properties of original coal and two lithotypes concentrates including helium density, methanol density, FTIR spectra, the amount of oxygen functional groups and swelling properties using pyridine as solvent. The results show that in the case of material under study the coal rank does not preponderate the effect of maceral composition. This third issue was addressed by performing adequate sorption experiments carried out at 298 K at low pressure on basic coal sample and two lithotypes concentrates. The tendency of adsorption capacity of CO to depend on maceral composition was confirmed as it increases with the content of vitrinite. The Dubinin–Radushkevich equation shows a very good agreement with all the experimental data obtained for both lithotypes concentrates and basic coal under investigation.