Manufacture of calcium-based sorbents for high temperature cyclic CO2 capture via a sol–gel process

Abstract

A CaO sorbent with high reactivity for cyclic high temperature CO2 capture was synthesized using a standard sol–gel process with citric acid as the chelation agent. The cyclic CO2 capture performance of the new sorbent was compared with that of the sorbents derived from commercial micro- and nano-sized CaCO3. The new CaO sorbent achieved a high CO2 capture capacity of 0.51gCO2/gsorbent under mild calcination conditions and retained an acceptable CO2 capture capacity of 0.20gCO2/gsorbent under severe calcination conditions after 20 cycles, much higher than those of the sorbents derived from commercial CaCO3 under the same reaction conditions. In addition, the new sorbent had a very rapid reaction rate at the initial reaction stage, achieving a calcium conversion ratio of 60% within 20s. Microscopic images showed that well-dispersed particles with an average size of about 200nm were formed within the sorbent. The new sorbent also had a better sintering-resistant property than the other sorbents tested during multiple calcination/carbonation cycles.