KINETICS OF FLUE-GAS DESULFURIZATION AT LOW-TEMPERATURES - NONIDEAL SURFACE-ADSORPTION MODEL

In this work the kinetic model and parameters describing best the desulfurization reaction at low temperature and at conditions prevailing in the exhaust gases of coal-fired plants are reported. A careful design of experiments led to the scheme of reactions. Assuming that the slow step was the adsorption of the gaseous sulfur dioxide on the surface of calcium hydroxide, a kinetic discrimination among adsorption models was performed, obtaining the best results with a mathematical model taking into account the nonideal behavior of the solid surface. A careful experimental design was planned to study the influence of oxygen and carbon dioxide concentrations and of the temperature and relative humidity on the kinetics of the process. In the first case, no influence of any of the variables was observed and, in the second case, an Arrhenius-type relation for the temperature and an exponential expression for the relative humidity were obtained. The kinetic model and parameters reported in this work are useful for the design and optimization of desulfurization processes at low temperatures.