Kinetics study of the SO2 sorption by Brazilian dolomite using thermogravimetry

Sulfur emission in coal power generation is a matter of great environmental concern. Limestone sorbents are widely used for reducing such emissions. This work applies thermogravimetry to determine apparent activation energy and frequency factor on the sorption of SO₂ by limestone. The kinetic parameters were determined from Arrhenius plots generated from TG/DTG measurements. The experiments were carried out under isothermal conditions between 600 and 900 °C. A natural dolomite with a mean size of 650 μm was used. The Arrhenius plot shows that there is a clear change on reaction mechanism in the range of temperatures between 800 and 875 °C. Supposedly, beyond 850 °C sintering comes to increasingly restrain reaction. For temperatures up to 850 °C the frequency factor and the apparent activation energy resulted, respectively, 1.410 s⁻¹ and 8.8 kJ mol⁻¹.