Sol-gel-derived, CaO-based, ZrO2-stabilized CO2 sorbents

We report the synthesis of CaO-based, ZrO2-stabilized CO2 sorbents using a sol-gel technique. In addition, the influence of different synthesis parameters, i.e. the calcium precursor, the condensation time and the ratio of Ca2+ to Zr4+ on the morphology and the CO2 uptake of the materials was evaluated. The morphology and the chemical composition of the materials were characterized using X-ray diffraction, N2 physisorption and scanning electron microscopy whereas the CO2 uptake of the materials was determined using a thermogravimetric analyzer and a packed bed reactor. After 90 cycles of the repeated calcination and carbonation reactions, the CO2 uptake of the best sorbent was 0.34 g CO2/g sorbent exceeding the performance of the reference limestone by 160%. The favorable CO2 capture characteristics of the synthetic CO2 sorbent were attributed to the formation of a finely dispersed, high Tammann temperature calcium zirconate framework, which minimized thermal sintering.