Calcination–carbonation durability of nano CaCO3 doped with Li2SO4

Abstract

Li2SO4 doped nano CaO (Li2SO4@nano CaO) based CO2 adsorbent has been developed to improve calcination–carbonation durability. Li2SO4@nano CaO adsorbent was obtained by calcination of Li2SO4 doped nano CaCO3 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 Li2SO4@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 Li2SO4 content of 3.0–5.0wt.%. Alternatively, pure nano CaO maintains only a 27.3% conversion at the same conditions. A physical property analysis reveals that the superior performance of Li2SO4@nano CaO adsorbent is attributed to the pore diameter enlargement and to the increase of macro-pore proportion due to Li2SO4 incorporation. Moreover, the carbonation and calcination rates of Li2SO4@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 (Li2CO3 and LiCl), Li2SO4@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.