Optimization of a lime-based sorbent for carbonation at low temperature enhanced by water vapor

Carbonation reaction of lime modified by small amounts of MgO was studied by submitting pelletized samples to the exhaust gas of a petrol engine at about 100 °C. The results showed that either the kinetic or the diffusion behavior is non-linearly dependent with the addition of MgO. Moreover, there is an optimum MgO percentage that enhances diffusion and ultimate sample conversions. Samples with 10% and 5% of additive showed faster initial kinetic and greater conversion, respectively. These results demonstrate that a small addition of MgO can increase the reactivity, sorption capacity and gas diffusion. Finally, the studied experiments revealed an intense interaction between CO2 and magnesium oxide. Theoretical analysis of the final conversion parameters suggests an optimized MgO concentration of about 7%.