Carbonation Performance of NaNO3 Modified MgO Sorbents

NaNO 3 modified MgO sorbents have a large theoretical CO 2 capture capacity, but their practical capture performance at medium temperatures (350–400 °C) is poor for the high thermodynamic equilibrium partial pressure of CO 2 at these temperatures. The thermodynamic limitations for NaNO 3 modified MgO sorbents can be relaxed by adding alkali or alkaline earth carbonates, and the effective carbonation temperature can be shifted to the higher temperatures (350–400 °C) to satisfy the requirement of fast kinetic reactions. In this paper, the CO 2 absorption characteristics of NaNO 3 modified MgO with or without CaCO 3 are compared experimentally to verify the promoting effects of CaCO 3 . Based on the CaCO 3 promoting theory, the methods of stage heating during carbonation and partial decomposition during regeneration were adopted to improve the CO 2 absorption ability of NaNO 3 modified MgO sorbents at 350 °C. Combined with the composition of fuel gas, effects of increasing CO 2 partial pressure and H 2 O were tested, and they both accelerated the carbonation rates of the sorbents, which forecasted the application potential of NaNO 3 modified MgO sorbents.