(67g) Development of Nano-TiO2 Promoted CaO Adsorbent for Enhanced CO2 Capture at High Temperatures: Role of Crystal Level Properties

Calcium looping (CaL) is a promising regenerative process involves CO₂ capture from flue gas using multi-cycle carbonation and calcination at high temperature. In this work, we investigate the sorption capacity, and kinetics of nano-TiO₂ promoted CaO synthesized from the commercially available micron size calcium carbonate. The optimum wt. % of nano-TiO₂ and sorption temperature of the sorbents was explored. The morphology of the uncoated and coated CaCO₃ with different wt. % (1 to 10 wt. %) of nano-TiO₂ was analyzed by FESEM. The CO₂ sorption experiments were carried out in a Thermogravimetric analyzer under CO₂ atmosphere (0.02 MPa) at different temperatures (600^oC, 650^oC and 700^oC). The crystallite size, strain and lattice parameters were estimated through Rietveld refinement of XRD data. The results demonstrate that the sorption capacity is enhanced several times for nano-TiO₂ promoted CaO than pure CaO obtained from micron and nano-size CaCO₃. The result shows that small amount of nano-TiO₂ provide porous structure, smaller crystallite size and high strain inside the CaO crystal during decomposition of CaCO₃, which improve the sorption capacity of CaO by 10 times in the first step. In general a substantial improvement is observed for subsequent cycles indicating nano-TiO₂ promoted CaO is better materials for CO₂ capture. The experimental results were fitted with theoretical models based on the shrinking core model and kinetic parameters were calculated and correlated with the crystal properties of CaO in presence of nano-TiO₂.