Pressure Dependence of the Low Temperature Carbonation Kinetics of Calcium Oxide for Potential Thermochemical Energy Storage Purposes and Sustainable CO<sub>2</sub> Fixation
Georg Gravogl, Felix Birkelbach, Danny Müller, Christian L. Lengauer, P. Weinberger, R. Miletich
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.