Kinetic model for the reaction between SO<Subscript>2</Subscript> and coal fly ash/CaO/CaSO<Subscript>4</Subscript> sorbent

Summary

The reaction between SO<Subscript>2</Subscript> and sorbent prepared from coal fly ash, CaO and CaSO<Subscript>4</Subscript> were investigated and modeled. The experiments were conducted using thermogravimetric analysis at isothermal conditions, where the rate measurements were carried out in the temperature range from 60 to 140&deg;C. The kinetics of the sulfation reaction is characterized by a dramatic decrease in the rate of reaction at the initial period of reaction time and the sorbent is left partially converted. Using isoconversional method, the activation energy of the sulfation reaction was found to be independent on the conversion of the sorbent. A one step global model was then proposed and the model based on almost second order (<Emphasis Type=”Italic”>n</Emphasis>=2.2) reaction was found to fit the kinetic data. Based on the propose model, the activation energy and frequency factor for the sulfation reaction was found to be 22.9 kJ mol<Superscript>-1</Superscript> and 64.4 min<Superscript>-1</Superscript> respectively. The model was found to give a good prediction of the conversion-time curve for experimental run not used in the development of the model. The value of activation energy obtained using the proposed model was found to be in agreement with the value calculated using the isoconversional method.