Surface textural changes during reaction of CaCO3 crystals with SO2 and O2 (air). 2. Large crystal faces, 670–1070 K
1995; Elsevier BV; Volume: 74; Issue: 7 Linguagem: Inglês
10.1016/0016-2361(95)00060-i
ISSN1873-7153
AutoresD. Carl Anderson, Peter Anderson, Andrew K. Galwey,
Tópico(s)Gas Sensing Nanomaterials and Sensors
ResumoElectron microscopic observations of (100) cleavage faces of calcite crystals shows that reaction with SO2 + O2 (air) results in significant surface modification. Sulfate formation becomes significant above 850 K and the observations are explained by the following mechanism. Calcium oxide, formed by CaCO3 dissociation, reacts with SO2 and the CaSO3 so formed is oxidized. The CaSO4 product constitutes an adherent barrier layer that limits the extent of reaction, an important consideration in development of this method for more effective flue gas desulfurization. The textural evidence suggests that the concurrent chemical steps mentioned require considerable mobility of the species participating in the surface/solid reactions. Migration may occur across surfaces, as in sintering, but here appears to extend to local, temporary or partial melting. Reaction is promoted by KI and here again the textural evidence is consistent with superficial fusion.
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