The objective of this work was to determine the efficiency of activated chars produced from two different lignites to remove sulfur dioxide from industrial flue gas. The lignites used differ mainly in their ashes and water contents. The chars were produced at semi-pilot scale (0.5 t) in rotary kiln, and in our optimized conditions of temperature, the specific surface reachs 372 m~2/g (pyrolysis temperature 800℃) for the best char. In order to investigate the effect of surface oxi-genated groups, a simple and mild post-oxidation treatment (40 min at 320℃ in air) was performed. The dynamic adsorption of SO_2 was realized at 100℃ in controlled atmosphere containing O_2, H_2O, SO_2 and N_2 as a balance. In these conditions 70 mg SO_2/g can be adsorbed by the best sample. After six adsorption/desorption cycles for the best char, the decrease of adsorption capacity is close to 20%. The oxidation of the char surface leads to a sensible decrease of its adsorption capacity. This could be explained by a simultaneous increase of the basic surface groups which should enhanced SO_2 adsorption and acidic groups which seem to be involved in the deactivation process. The influence of lignite pre-drying (before pyrolysis) on adsorption behavior of char is limited. Finally, once more, the lack of relation between surface area and SO_2 adsorption capacity is observed. That means that considering polar and acidic molecules, both porosity and surface chemistry play important role.
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