Calcined calcium magnesium acetate as a superior SO2 sorbent: I. Thermal decomposition

Abstract

AbstractThe reactivity of the calcination product of calcium magnesium acetate (CMA) as a possible dry desulfurization agent was evaluated. The first step in the dry desulfurization reaction—the thermal decomposition of CMA—was investigated by determining the decomposition reaction in three steps: 1. the evaporation of water starting at 65°C, 2. the conversion of CMA into CaCO3 and MgO starting at 275°C, and 3. the decomposition of CaCO3 to CaO starting at 580°C. The pseudo‐first‐order kinetic equation was observed for the CMA decomposition to CaCO3 + MgO, with an activation energy of 165.5 kJ/mol. The decomposition of CaCO3 to CaO also obeyed the pseudo‐first‐order kinetics, with an activation energy of 200 kJ/mol. As discussed in Part II of this series, the calcination product from CMA is quite reactive due mainly to the large porosity and internal surface area generated on the removal of the acetate group during the decomposition reaction. Furthermore, as will be shown in Parts II and III, the sulfation capacity of the calcined CMA is much greater than that of conventional sorbents because its sulfation rate does not level off until complete conversion and its MgO content is also sulfated at temperatures lower than about 900°C.