Pressure Dependence of the Low Temperature Carbonation Kinetics of Calcium Oxide for Potential Thermochemical Energy Storage Purposes and Sustainable CO₂ Fixation

Abstract

Abstract The pressure effect on the carbonation behavior of CaO as model compound is studied under mild hydrothermal conditions, as relevant to sustainable geological CO 2 sequestration and for potential utilization in thermochemical energy storage. Reaction yields are determined experimentally by means of in situ powder X‐ray diffraction using CaO powder samples in a controlled reaction with CO 2 under gas pressures between 1.0 and 5.0 MPa and at temperatures between 298 and 373 K. The results show a two‐step conversion of CaO to CaCO 3 , involving Ca(OH) 2 as a reactive intermediate, with differing influences of the microstructures on the individual reaction sub‐steps. A kinetic evaluation of the experimental data delivers a high rate‐enhancing effect of temperature on the hydration reaction, whereas the CaCO 3 formation is strongly dependent on the available CO 2 gas pressure. With this systematic investigation the optimal pressure and temperature conditions for this reaction system can be determined delivering a contribution to a sustainable climate and energy management.