Kinetic Parameterization of the Effects of Atmospheric and Self-Generated Carbon Dioxide on the Thermal Decomposition of Calcium Carbonate
Abstract
The kinetics of the thermal decomposition of CaCO3 is significantly influenced by atmospheric and self-generated CO2 due to the reversibility of the reaction. More detailed understanding of this well-known phenomenon is desired for establishing an effective Ca-looping in the CaO–CaCO3 system for energy storage and CO2 capture. This article shows the universal kinetics of the thermal decomposition of CaCO3 over different temperatures and partial pressures of CO2 (p(CO2)) with the aid of an accommodation function (AF) composed of p(CO2) and equilibrium pressure. An analytical form of AF with exponents (a, b) was derived based on the kinetic considerations for the consecutive elementary steps of the surface nucleation and interfacial reaction. The overall kinetics of the thermal decomposition of CaCO3 were described universally over different temperatures and p(CO2) values by introducing the AF, in views of the isoconversional and isothermal kinetic relationships using the extended Friedman and experimental master plots, respectively. The universal kinetic description was extended to the kinetic modeling based on the physico-geometrical consecutive process comprising an induction period (IP), a surface reaction (SR), and a phase boundary-controlled reaction (PBR). The proposed kinetic approach enables parameterizing the CO2 effect via the optimized (a, b) and tracking changes in the CO2 effect as the physico-geometrical reaction step advanced from IP to PBR via SR. Furthermore, using the established universal kinetic description across different temperatures and p(CO2) values, a challenge was set to quantify the contributions of atmospheric and self-generated CO2 on the kinetics.
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