Preparation of activated carbons for SO 2 adsorption by CO 2 and steam activation

Abstract

Taixi anthracite was used as a precursor to prepare microporous activated carbons for SO 2 adsorption from flue gas. In this work the activated carbons were prepared by physical activation with carbon dioxide and steam, respectively. Specifically, the effects of activation temperature and burn-off degree on the physico-chemical properties of two series were comparatively studied. The physical properties of the AC samples on the SO 2 adsorption were also investigated. The surface area and porosity of sample was studied by N 2 adsorption at 77 K. The surface chemistry was evaluated by FTIR. The BET surface areas and micropore volumes of steam-activated carbons are always larger than those by CO 2 activation except the samples with burn-off above 70%. The CO 2 activation leads to samples with continuous evolution of ultramicropore volumes. At higher activation temperature, the decrease of micropore volume is attributed to an external burn-off for both series. All the activated carbons show basic properties, which makes these samples suitable for SO 2 adsorption. It is observed that a large micropore volume does not necessarily assure an optimal adsorption of SO 2; rather, the pore size and pore size distribution should be considered as important parameters.