Reactivity of highly cycled particles of CaO in a carbonation/calcination loop

Calcium oxide can be an effective sorbent for separating CO2 at high temperatures. The carbonation reaction is the basis for several proposed high temperature CO2 capture systems when coupled with a calcination step to produce a pure CO2 stream. Fresh calcined lime is known to be able to carbonate very readily at appropriate temperatures, but the average sorbent particle in a capture system using CaO as regenerable sorbent has to undergo many carbonation/calcination cycles. This work investigates the carbonation reaction rates in highly cycled sorbent particles of CaO (20–100 s of carbonation/calcination cycles). A basic reaction model (homogeneous model) has been proved to be sufficient for interpreting the reactivity data obtained under different conditions: partial pressure of CO2, particle sizes and other relevant operation variables for the carbonation/calcination loop. The intrinsic rate parameter was found to be between 3.2 and 8.9 × 10−10 m4/mol s in agreement with other values found in the literature.