A STUDY OF CAO-SO2 INTERACTION

The interaction of SO2 (0.3 vol% in He) with CaO resulting from therma l decomposition of commercial CaCO3 has been investigated in a wide ra nge of temperatures. TPR experiments, from 298 to 1173 K, carried out in a thermobalance and in a vertical flow reactor coupled to a GC, iso thermal reaction experiments and XRD analysis of sulphated samples ind icate that below 773-873 K CaSO3 is formed. As the temperature increas es from 873 to 1073 K a mixture of CaSO3, CaSO4 and CaS is produced an d at temperatures above 1073 K only CaSO4 and CaS appear. Also, TPR an d isothermal reaction experiments allow us to distinguish surface and bulk CaSO3 formation. The boundary temperature for both processes, sur face and bulk formation, occurs at 573 K.