Influence of the activation temperature on the SO2 removal capacity and mechanical performance of pelletized activated chars

The influence of steam activation temperature on the SO2 removal capability of subbituminous coal char pellets (SCCP) as well as the changes in their mechanical properties, were studied. The SCCP were prepared by pressing at 125 MPa a blend of a char, obtained by carbonization at 850 degreesC, and a commercial coal tar pitch. After a curing stage in air at 200 degreesC and a heat treatment at 900 degreesC in nitrogen, the SCCP were activated with steam (10g H2O min(-1)) for two hours at several temperatures: 600, 700, 7 30 and 800 degreesC. The SO2 adsorption capacity tests carried out at simul ated flue gas conditions (100 degreesC, 10% H2O, 6% O-2, Is space velocity) show an important increase in the amount of adsorbed SO, of the activated SCCP with respect to parent ones, whereas their mechanical performance decr eases in the same proportion, mainly in the interval 700-750 degreesC. Incr easing the temperature of activation, the SCCP undergo significant changes in textural features (total surface area measured in N-2 and CO2, pore volu me) as well as in surface oxygenated groups, as shown by TPD experiments. T here is an optimum ratio between both parameters (around 8 mu mol g(-1)) fo r the SO2 conversion at the studied conditions.