Modification of CaO-based sorbents prepared from calcium acetate for CO2 capture at high temperature

CaO-based sorbent is considered to be a promising candidate for capturing CO2 at high temperature. However, the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In this study, CaO was derived from calcium acetate (CaAc2), which was doped with different elements (Mg, Al, Ce, Zr and La) to improve the cyclic stability. The carbonation conversion and cyclic stability of sorbents were tested by thermogravimetric analyzer (TGA). The sorbents were characterized by N-2 isothermal adsorption measurements, scanning electron microscopy (SEM) and Xray diffraction (XRD). The results showed that the cyclic stabilities of all modified sorbents were improved by doping elements, while the carbonation conversions of sorbents in the 1st cycle were not increased by doping different elements. After 22 cycles, the cyclic stabilities of CaO-Al, CaO-Ce and CaO-La were above 96.2%. After 110 cycles, the cyclic stability of CaO-Al was still as high as 87.1%. Furthermore, the carbonation conversion was closely related to the critical time and specific surface area. (C) 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.