Kinetic study of low-temperature sulfur dioxide removal reaction by sodium carbonate using random pore model.

An experimental investigation of low-temperature SO2 removal reaction by porous sodium carbonate was carried out via thermogravimetry. Further, mathematical modeling was employed based on the random pore model to study the kinetics of this reaction. The experiments were performed at various temperatures (100-250 °C) and different SO2 concentrations (0.13-1.12 vol%). The initial slope method was used to determine dependency of the reaction rate constants versus temperature. First-order kinetics with respect to gaseous reactant was observed and the activation energy was determined as 22.5 kJ mol-1. Furthermore, product layer diffusivities were evaluated by comparison of experimental data with the model predictions. The mechanism was determined as competition between pore diffusion and surface reaction (mixed control regime) at initial stages, and product layer diffusion at later steps of the reaction. These random pore model predictions indicated good agreement with experimental conversion-time data under various conditions. The resulting kinetic parameters are essential for engineering calculations of SO2 removal from the coal-based power plants through low-temperature flue gas desulfurization.