QUANTUM CHEMICAL STUDY ON THERMAL DECOMPOSITION MECHANISM OF CALCIUM CARBONATE

A detailed quantum chemical calculation is performed at the MP2(full)/6-311G* level to explore the mechanism of calcium carbonate thermal decomposition. Four microscopic pathways are identified. The rate constants of rate-determining steps in four pathways are calculated over a temperature range 298–1200 K. The calculating results show that only path A (R( CaCO 3) → IM 1 → P( CaO + CO 2)) and path B (R( CaCO 3) → IM B1 → IM B2 → P( CaO + CO 2) have contributions to the CaCO 3 thermal decomposition, and path A may be more favorable than path B. The present theoretical studies may provide useful information in understanding reaction mechanism of metal carbonates at the molecular level.