CaO-based sorbents looping cycles for CO2 capture

03/23/2011

Carbon dioxide capture was studied using CaO-based sorbents looping cycle technology. These sorbents, natural rocks, such as limestone or dolomite, or synthetically produced can be used to capture CO2 from combustion flue gases sources and provide a pure stream of CO2 suitable for sequestration or catalytic transformation. This process contributes to decreasing the CO2 emissions to the atmosphere and, therefore, to a more sustainable environment. In this study a set of calcium and support precursors were used to prepare synthetic supported calcium oxide; a synthetic calcium oxide sorbent; and supports. Synthesis methods used were: sol-sol; sol-gel and dry impregnation. The sorbents prepared were characterized by: x-ray diffraction, N2 adsorption, SEM and laser granulometry. Sorbents reactivity tests were performed using (i) a commercial CaCO3 (reference), (ii) synthetic supported sorbents and (iii) synthetically produced CaO through sol-gel method. Results obtained with commercial CaCO3 showed the typical behavior described in the literature for these sorbents. The synthetic supported sorbents, prepared through sol-sol method, show less activity decay through cyclic operation ? the support decreases the sintering phenomenon. Therefore, dispersing a more reactive calcium oxide in alumina, using the same sol-sol method, may lead to a high performance sintering resistant sorbent. Synthetic CaO prepared using the sol-gel method showed higher specific surface area than commercial CaO and better selectivity towards CO2 rather than H2O. It maintained its reactivity throughout 20 cycles and loss ~55% over 70 cycles, still the residual value is 0.24gCO2/gCaO. Nonetheless this is 200% better than natural limestone residual carrying capacity.

Authors in the community:

• 

  C

  Carolina Alfonsin Outeda

  ist169148

Supervisors of this institution:

• 

  M

  Maria Filipa Gomes Ribeiro

  ist11988

• 

  C

  Carla Isabel Costa Pinheiro

  ist12547

chemical-engineering - Chemical engineering

eng - English

Instituto Superior Técnico