Ca ion-exchanged coal char as H2S sorbent

H2S removal using Ca ion-exchanged coal char was studied in a fixed bed rea ctor at a temperature of 900 degrees C. Yallourn, an Australian brown coal was used for ion exchange. The CaO obtained from the pyrolysis of Ca ion-ex changed coal was finely dispersed in the char and much more reactive toward H2S than that from limestone. Ca ion-exchanged coal char showed high H2S c apture and almost no emission of H2S was observed in the earlier reaction s tage. At a reaction time of 100 min, the S/Ca atomic ratio in Ca ion-exchan ged coal char increased to 1.2. This was due to H2S capture capacity of bot h the coal char itself and the CaO distributed in the char. The sorption ca pacity of char was determined as 1.5 mmol-H2S/g-char. The desulfurization c haracteristics of calcined limestone strongly depended on the particle size , whereas those of Ca ion-exchanged coal char was almost independent of the char particle size. (C) 1999 Elsevier Science Ltd. All rights reserved.