Calcination–carbonation durability of nano CaCO3 doped with Li2SO4

Li 2 SO 4 doped nano CaO (Li 2 SO 4 @nano CaO) based CO 2 adsorbent has been developed to improve calcination–carbonation durability. Li 2 SO 4 @nano CaO adsorbent was obtained by calcination of Li 2 SO 4 doped nano CaCO 3 that was prepared by a simple wet solution impregnation method. The morphology and microstructural properties of the adsorbent were examined by scanning electron microscopy (SEM) and nitrogen physisorption tests, and its cyclic calcination–carbonation performance was evaluated by thermogravimetric analysis (TGA). The results show that Li 2 SO 4 @nano CaO adsorbent maintains a 51.0% CaO conversion after 11 cycles under the calcination temperature of 750   °C and carbonation temperature of 600   °C with an optimized Li 2 SO 4 content of 3.0–5.0   wt.%. Alternatively, pure nano CaO maintains only a 27.3% conversion at the same conditions. A physical property analysis reveals that the superior performance of Li 2 SO 4 @nano CaO adsorbent is attributed to the pore diameter enlargement and to the increase of macro-pore proportion due to Li 2 SO 4 incorporation. Moreover, the carbonation and calcination rates of Li 2 SO 4 @nano CaO adsorbent are accelerated compared with nano CaO adsorbent, and the complete decomposition temperature is at least 15   °C lower. In comparison with the adsorbent doped with other lithium salts (Li 2 CO 3 and LiCl), Li 2 SO 4 @nano CaO adsorbent possesses the best durability under equivalent doping conditions. Furthermore, the positive linear correlation between the complete decomposition temperature and CaO conversion has been maintained.