Facile fabrication of mesoporous CaO sorbents using simple salt as a pore template in a template-assisted and spray-drying synthesis method

A combined templating and spray-drying synthesis technique has been proposed to fabricate a mesoporous CaO sorbent for CO2 capture applications. A simple inorganic salt, NaCl, was used as an alternative pore template to conventional, expensive organic templates. The effects of different NaCl-to-calcium precursor ratios (w/w) on porosity characteristics and CO2 capture performance of the synthesized sorbents were investigated. Cyclic CO2 capture performances of the sorbents were studied under mild and severe calcination conditions and compared with CaO derived from commercial CaCO3 (99%, Sigma-Aldrich) as a benchmark. Subsequent to 20 cycles of carbonation and severe calcination, CaO sorbent synthesized using a NaCl-to-CG weight ratio of 0.3 (denoted as CaO-0.3) exhibited a capture performance of 0.225 ± 0.005 g CO2/g sorbent whereas the benchmark sorbent exhibited a CO2 uptake of 0.082 ± 0.002 g CO2/g sorbent. This corresponds to maximum improvement of 165% in CO2 uptake under severe conditions for CaO-0.3 sorbent. Furthermore, the highest pore volume and pore area were also observed for CaO-0.3 sorbent at 17.6 nm and 12.5 nm, respectively. A BET surface area of 23 ± 1 m2/g and a total pore volume of 0.149 ± 0.008 cc/g were measured for this sorbent, which compares favourably with that of commercial CaCO3.