Surface textural changes during reaction of CaCO3 crystals with SO2 and O2 (air). 1. Small crystals, 670–1070 K
1995; Elsevier BV; Volume: 74; Issue: 7 Linguagem: Inglês
10.1016/0016-2361(95)00059-e
ISSN1873-7153
AutoresD. Carl Anderson, Peter Anderson, Andrew K. Galwey,
Tópico(s)Industrial Gas Emission Control
ResumoThe significant changes of surface texture in CaCO3 crystallites due to reaction in an equimolar SO2O2 mixture were examined by scanning electron microscopy. Surface modifications were extensive above 870 K, which is close to the temperature of CaCO3 dissociation and of CaSO3 oxidation. It appears that both rate processes participate in the conversion of calcite to CaSO4 by reaction with SO2 under oxidizing conditions. The results confirm the production of sulfate above 870 K, but this generation of product across the surfaces represents a barrier to gas-solid contact that prevents complete reaction of the CaCO3 particles. The observations show that potassium ions enhance CaSO4 formation, probably by promoting fusion of the barrier layer, and that rapid heating does not disrupt calcite crystals sufficiently to increase the reactant surface area. The product barrier layer is identified as controlling both rate and extent of the reaction of calcite in desulfurization processes.
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