Granular KOH-activated carbons from coal-based cokes and their CO2 adsorption capacity

Granular activated carbons (>0.5 mm) have been prepared by KOH activation at 800 °C of cokes, size fraction of 0.63-1.25 mm, from high volatile bituminous coals. The most suitable coal is distinctive by the volatile matter content of about 33 wt.% and negative dilatation in the Audibert-Arnu test. The highest mechanical strength of granules is found for the activated carbons from cokes produced at 800-850 °C. They are microporous materials with porous texture parameters decreasing as the KOH/coke ratio varies from 4:1 to 2:1 in the range: surface area SBET 1800-1200 m2 g−1, micropore volume VDR 0.71-0.48 cm3 g−1 and mean micropore size L0 1.12-0.76 nm. The granular activated carbons represent interesting properties for gas adsorption application. CO2 uptake measured at 273 K amounts to 140 cm3 g−1 under atmospheric pressure and 370 cm3 g−1 under 3.5 MPa, corresponding to 6.2 and 15.7 mmol g−1, respectively.