Regenerable CaO sorbents for SO2 retention:: carbonaceous versus inorganic dispersants

In this study, the behaviour of different activated carbons and some inorganic solids (alumina, silica, titania, magnesia and silicon carbide) as dispersants for Ca(OH)(2)-derived CaO under two cycles of SO, retention at 300 degreesC, is analysed. Before performing the second SO2 adsorption, a regeneration treatment in N-2 at 880 degreesC is carried out. During the first retention of SO2 no influence of the dispersant was appreciated, being CaO the only phase responsible of SO2 capture. However, during the second SO2 adsorption the nature of the dispersants is important. Thus, comparing the behaviour of the inorganic solids with that exhibited by the activated carbons, it is observed that the activity loss, after the regeneration treatment, was significantly reduced when the activated carbons were used, especially at high dispersant content. The most effective dispersants were found to be those with meso and macroporosity which prevent the CaO (particle size of about 5 nm) sinterisation-agglomeration. This feature was exhibited by the activated carbons chosen. (C) 2002 Elsevier Science Ltd. All rights reserved.