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.

Acceleration Effect of Atmospheric Water Vapor on the Thermal Decomposition of Calcium Carbonate: A Comparison of Various Resources and Kinetic Parameterizations

“…102,103 The thermal decomposition of CaCO 3 is one of such reactions, where the self-generated CO 2 significantly retards the reaction. 11,33 The optimized nonintegral value of n (i.e., 1.56−1.70) should be interpreted as an apparent value with the possible contribution from the reaction geometry of the particle assemblage, although sampling and measurement conditions for collecting the kinetic data were carefully selected to reduce the influences of the mass and heat transfer phenomena.…”

“…The apparent E a value for the established reaction stage determined by the extended Friedman plot method coincides with the majority of the reported values for the thermal decomposition of CaCO 3 in an inert gas atmosphere, including reduced pressure conditions. 9,11,33,73 The kinetics of the thermal decomposition under different p(H 2 O) values are described using a single set of kinetic triplets (i.e., E a , A, and f(α)), and the magnitude of the acceleration effect of water vapor is expressed by the exponent a in the AF (eq 7). Therefore, the kinetic behavior of the thermal decomposition of CaCO 3 at a select temperature and p(H 2 O) value can be simulated using a single set of kinetic parameters involving the exponent a in the AF.…”

“…56−61 The universal kinetic description was also achieved for the thermal decomposition of CaCO 3 by considering the partial pressure of CO 2 and the equilibrium pressure of the reaction (eq 1). 33,62,63 The other atmospheric condition influencing the thermal decomposition of CaCO 3 is water vapor pressure (p(H 2 O)). The acceleration effect of water vapor on the thermal decomposition of CaCO 3 has been reported by different researchers.…”

“…This relatively simple reaction system in reaction stoichiometry and thermodynamics exhibits complex kinetic behaviors, which have been studied in each generation as one of the model reactions in the solid–gas system using cutting-edge knowledge and techniques. − The complexity of the kinetics is mainly due to the heterogeneous characteristics of both forward and reverse reactions in eq . As in many reactions of solids, the reactivity varies with the surface properties of the solid reactant, and the reactions are constrained in the physico-geometrical reaction scheme of the surface reaction (SR) and the subsequent advancement of the reaction interface toward the center of the solid reactants. − The removal and intake of CO 2 by diffusion through the surface product layer in the forward and reverse reactions in eq , respectively, significantly regulate the overall kinetics of each reaction.…”

“…As in many reactions of solids, the reactivity varies with the surface properties of the solid reactant, and the reactions are constrained in the physico-geometrical reaction scheme of the surface reaction (SR) and the subsequent advancement of the reaction interface toward the center of the solid reactants. − The removal and intake of CO 2 by diffusion through the surface product layer in the forward and reverse reactions in eq , respectively, significantly regulate the overall kinetics of each reaction. Moreover, the thermal decomposition of CaCO 3 is hindered by the effects of atmospheric and self-generated CO 2 . ,,,,− In many cases, the CaO carbonation ceases midway because of the difficulty of CO 2 diffusional intake due to blockage of the surface product layer. , In addition, the morphological changes that inevitably occur during reaction cycling cause the maximum degree of progress during the CaO carbonation to deteriorate, which directly influences CO 2 absorption and thermal energy storage capacities. Considerable efforts have been made to improve the Ca-looping system based on eq , including the reforming of the solid reactants by different chemical and physical techniques (doping, supporting, milling, annealing, etc.…”