(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 (600oC, 650oC and 700oC). 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.