Modeling the thermal decomposition of solids on the basis of lattice energy changes - Part 1: Alkaline-earth carbonates

摘要

Decompositions of many solids are of the form: A(s) --> B(s) + gases. As real examples of this reaction pattern, the decompositions of some alkaline-earth metal (Ca, Sr, Ba) carbonates MCO3(s) --> MO(s) + CO2(g) were selected for modeling, The crystal structures the reactants and the solid product oxides have been reported in the literature. Symmetry-controlled routes for transforming the reactant into the solid product oxide were devised as possible decomposition pathways. Lattice energies of the reactants, the conjectured transient intermediate structures, and the final products were then estimated by crystal modeling procedures, and profiles of energy changes during the proposed decomposition routes were constructed. Barriers in these energy profiles are compared with experimental values reported for the activation energies of the thermal decompositions. (C) 1998 Academic Press. [References: 56]