FLUE-GAS DESULFURIZATION AT LOW-TEMPERATURES - CHARACTERIZATION OF THE STRUCTURAL-CHANGES IN THE SOLID SORBENT

This work has analysed the evolution of the structural properties, por e volume (V(p)) and surface area (S), of the solid sorbent during the reaction between SO2 and hydrated lime at low temperatures. Two differ ent types of experiments have been carried out: (i) experiments direct ed towards the analysis of the influence of the composition of the gas phase on the structural properties of the solid; (ii) experiments dir ected towards the analysis of the influence of the presence of the rea ction product, CaSO3 . H2O, on the structural properties. Some fluid-s olid reactions are characterized by incomplete conversion as result of premature pore closure at the surface of reacting particles; however, in the case under study it has been observed that when the maximum so lid conversion is reached, 0.6 mol SO2/mol Ca, there are still pore vo lume and surface area in solid. On the other hand the results obtained in this work show a linear decrease of the structural parameters, S a nd V(p), with solid conversion; the main decrease is produced in the r egion of mesopores (0.2-0.009 mum), which has been demonstrated to be the effective pore region for the desulfurization reaction.