Effect of Regeneration Temperature on the Composition and Carbon Dioxide Sorption Ability of a K₂CO₃/Al₂O₃Solid Sorbent in a Bubbling Fluidized Bed Reactor

Abstract

The effect of the regeneration temperature (150°, 250°, and 350°C) during multiple CO2 cyclic sorption-regeneration cycles of a K2CO3/Al2O3 solid sorbent in a bubbling fluidized bed reactor was evaluated in terms of the CO2 capture capacity and chemical composition of the solid sorbent. The CO2 capture capacity after regeneration at 150° and 250°C decreased with increasing cycle numbers, reaching approximately 57 and 78%, respectively, and 19.0 and 39.3%, respectively, of the original capacity after one and five regeneration cycles. This decline in the CO2 capture capacity was due to the accumulation of KHCO3 (at 150°C) and KAl(CO3)2(OH)2 (150° and 250°C) from their incomplete degradation back to the K2CO3/Al2O3 solid sorbent. When regenerated at 350°C, the CO2 capture capacity remained essentially constant in each cycle number because of complete desorption (no residual KHCO3 and KAl(CO3)2(OH)2). The formation mechanism of complex structure occurred similar to the one in a fixed bed reactor/thermogravimetric analyzer with lower regeneration temperature. The general operation conditions for K2CO3/Al2O3 solid sorbents are summarized.