Effect of Preparation Temperature on Cyclic CO₂ Capture and Multiple Carbonation−Calcination Cycles for a New Ca-Based CO₂ Sorbent

Abstract

The cyclic CO2 capture, transient phases change, and microstructure appearance of a new kind of Ca-based regenerable CO2 sorbent, CaO/Ca12Al14O33, obtained by the integration of CaO as solid reactant with a composite metal oxide of Ca12Al14O33 as a binder, were investigated by thermogravimetric analysis, XRD, and SEM at different preparation calcination temperatures. When the calcination temperature in the preparation stage is higher than 1000 °C, the cyclic CO2 capture of this new sorbent declines. The lowered CO2 capture may mainly be attributed to the formation of Ca3Al2O6, which decreases the ratio of CaO to binder in sorbent, and the severe sintering of sorbent occurs when calcined at such high temperatures in the preparation processes. These results suggest that the calcination temperature for this new sorbent should not be higher than 1000 °C in order to obtain its high reactivity. The performance of the new sorbent over 50 cycles was evaluated under mild and severe regeneration conditions, respectively. CaO/Ca12Al14O33 attained 41 wt % CO2 capture after 50 carbonation−calcination cycles under mild calcination conditions (850 °C, 100% N2), and the results obtained here indicate that the new sorbent, CaO/Ca12Al14O33, has significantly improved CO2 capture and cyclic reaction stability over multiple carbonation−calcination cycles compared with limestone and dolomite under mild calcination conditions. When more severe calcination conditions (980 °C, 100% CO2) were used, the capture of CaO/Ca12Al14O33 decreased from 52 wt % in the first cycle to about 22 wt % in the 56th cycle; however, the capture of CaO/Ca12Al14O33 sorbent over 56 cycles is still higher than that of dolomite and limestone under the same severe calcination conditions.

A Review of CO2 Capture by Absorption and Adsorption

“…with CaO (Aihara et al, 2001;Salvador et al, 2003;Roesch et al, 2005), some additives were found to be destructive or disadvantageous to the stability of adsorbents (Hasler et al, 2003;Lu et al, 2006) and to increase equipment capacity as well as operation cost. The modification of pore structure could be achieved by incorporation of Al into CaO to form mayonite (Ca 12 Al 14 O 33 ) (Li et al, 2006;Martavaltzi and 1: Propane tank; 2: Coil; 3: Syringe pump; 4: Valves; 5: Reactor; 6: Pressure gauge; 7: Thermocouple; 8: Heating tape; 9: Ice bath; 10: Oven. Fig.…”

Towards Solar Thermochemical Carbon Dioxide Capture via Calcium Oxide Looping: A Review

“…Reproduced with permission from Elsevier. (Li et al, 2006), CuO/CaO composite (Manovic et al, 2011), CaO calcined from mesoporous CaCO 3 (Iyer et al, 2004), thermal pretreatment of CaO (Can Ozcan et al, 2011), and CaO prepared with various precursors (Lu et al, 2006). This summary of the kinetic analyses demonstrates that the kinetics of the calcination and carbonation reactions vary widely depending on the sorbent source and gas atmosphere composition.…”

In situstudies of materials for high-temperature CO2capture and storage

“…Cycling studies of natural limestone show its capacity to reduce by as much as 90 mol% aer only the rst 20 cycles owing to sintering. 5 While one focus of recent research has been to alter the properties of CaO through synthetic methods with different additives such as Al 3 O 3 , Ca 12 Al 14 O 33 , or SiO 2 , [6][7][8] there is still a fundamental lack of understanding regarding how the carbonation reaction proceeds and what parameters control the function of absorbent materials.…”