Adsorptive removal of sulfur dioxide by Saskatchewan lignite and its derivatives

A non-equilibrium method using fixed bed microreactor was used to measure SO2 adsorption characteristics of chars and activated carbons derived from Saskatchewan lignite. SO2 breakthrough times and profiles were measured using lignite at a variety of temperatures, particle sizes and SO2 concentrations of 75–175 °C; 2–5.6 mm and 1000–5000 ppm, respectively. Adsorption was found to be a strong function of residence time and feed SO2 concentration, a moderate function of particle size and a weak function of temperature. There was a marginal difference in the adsorption capacity between lignite (15 mg SO2/g lignite) and the char obtained from the same starting amount of lignite (26 mg SO2/g char, or 17 mg SO2/g original lignite). Activation of lignite with steam resulted in an activated carbon, which had highest adsorption capacity of 93 mg SO2/g activated carbon.