Properties of CO2 adsorption for petrographically diverse ortho-lignites and some higher rank coals

A great deal of research has been done worldwide on the assessment of realistic CO 2 adsorption capacities of different coals, which is important for the understanding and predicting of processes associated with the geological storage of carbon dioxide (CO 2 ).The focus of this article is on measuring the CO 2 amounts adsorbed by coals regarding their petrographic type and coalification rank.Most of the samples were taken from the Velenje lignite seam (ortho-lignite, Slovenia).Samples of meta-lignites and bituminous coals from Hrastnik (metalignite, Slovenia), Raša (bituminous coal, Croatia) and the Sokolov Basin (meta-lignite, Czech Republic) have been analysed as comparing coals.Adsorption measurements were undertaken using the gravimetric method at the temperature of 21 °C and the CO 2 pressure of 3 MPa.The measurements show that different ortho-lignite lithotypes (dried, ground, and under 200 µm sieved material, compressed under uniaxial compression of 9 MPa and filled with CO 2 ) adsorbed on average 29 m 3 of CO 2 per tonne of lignite, varying from 22 to 39 m 3 of CO 2 per tonne of lignite.However, higher rank coals adsorbed slightly more CO 2 , that is, between 31 and 42 m 3 of CO 2 per tonne of coal.