Calcium-based sorbent doped with attapulgite for CO_2 capture

摘要

Attempt to enhance CO_2 uptake of calcium based sorbents by doping limestone with attapulgite was made and successfully achieved its effectiveness. The appropriate doping mode and optimal ratio were identified. The cyclic carbonation behavior was conducted under conditions of different carbonation temperature, calcination temperature, CO_2 partial pressure in carbonation and calcination atmosphere. Microstructure and compositions of sorbents were analyzed to serve as a supplement to the studies. Results show that the optimal doping ratio of attapulgite to calcined limestone was 15 wt.% in the process of hydration. The doped sorbent displayed much better CO_2 capture performance than the natural limestone by 128% increase after 20 cycles under the same condition (calcination at 950 ℃ in 100% CO_2 and carbonation at 700 ℃ in 15% CO_2/85%N_2). Excellent microstructure of the modified sorbent was created by doping attapulgite enabling higher CO_2 capture capacity. Ca_2SiO_4, Al_2O_3 and Ca_3Al_(10)O_(18) distributed in the sorbent by XRD analysis enhanced its sintering-resistant leading to slow decrease in CO_2 capture capacity during multiple cycles.