This paper proposes a response surface
methodology to evaluate
the influence of the particle size and temperature as variables and
their interaction on the sulfation process using two Brazilian limestones,
a calcite (ICB) and a dolomite (DP). Experiments were performed according
to an experimental design [central composite rotatable design (CCRD)]
carried out on a thermogravimetric balance and a nitrogen adsorption
porosimeter. In the SO2 sorption process, DP was shown
to be more efficient than ICB. The best results for both limestones
in relation to conversion and Brunauer–Emmett–Teller
(BET) surface area were obtained under central point conditions (545
μm and 850 °C for DP and 274 μm and 815 °C for
ICB). The optimal values for conversion were 52% for DP and 37% for
ICB. For BET surface area, the optimal values were 35 m2 g–1 for DP and 45 m2 g–1 for ICB. A relationship between conversion and pore size distribution
has been established. The experiments that showed higher conversions
also exhibited more pores in the region between 20 and 150 Å
and larger BET surface area, indicating that the amount of smaller
pores may be an important factor in the reactivity of limestones.