INFLUENCE OF LOW-RANK COAL CHAR PROPERTIES ON THEIR SO2 REMOVAL CAPACITY FROM FLUE-GASES .1. NONACTIVATED CHARS

The SO2 adsorption capacity of a series of chars obtained by N-2 pyrol ysis at different temperatures from a low-rank coal with high ash cont ent was assessed. The adsorption process was carried out at representa tive flue gas conditions (100 degrees C adsorption temperature, 1 seco nd residence time, 10% H2O v/v, 6% O-2 v/v, 1000 ppmv SO2). Chars obta ined by nitrogen pyrolysis at 500, 600, 700, 800 and 900 degrees C wer e characterized by the following techniques: XRD, AA, FTIR, Hg porosim etry, N-2 and CO2 surface areas, and acid-base titration. Correlations between the performance of these chars and their physicochemical feat ures were investigated. The SO2 adsorption capacity of pyrolized chars depends mainly on their surface area, but the content and type of fun ctional groups and their accessibility are also important parameters t o be considered. (C) 1997 Elsevier Science Ltd.