Sol–gel-Derived Synthetic CaO-Based CO2 Sorbents Incorporated with Different Inert Materials

Abstract

A series of CaO-based sorbents incorporated with different inert materials (Ca2SiO4, Ca3Al2O6, CaTiO3, CaZrO3, and MgO) were prepared by a simple citrate sol–gel method. The structure–property relationship of the sorbents was explored, and the cyclic CO2 capture capacity and stability of the sorbents were evaluated. It was found that the complexation time, dispersion agent, calcium precursor, and inert material had significant effects on the sorbent structure and performance. The best CaO-based sorbent stabilized by CaZrO3 (29.1 wt %) had a stable CO2 capture capacity of 0.45 gCO2/gsorbent over 30 consecutive cycles, which was mainly ascribed to the small grains, accessible pores, and homogeneous distribution of CaO and CaZrO3 in the sorbent. Under severe but more realistic conditions (10 min of carbonation in 15% CO2/N2 at 650 °C, 5 min of calcination in 80% CO2/N2 at 1000 °C), this sorbent exhibited a constant capacity of 0.16 gCO2/gsorbent (carbonation conversion of 29%) after 50 cycles.