Experimental and molecular dynamics study on decarbonization and sintering process of CaCO3 particles

The structural evolution and mass transport of calcium carbonate (CaCO 3 ) particles during high-temperature decarbonization are critical for thermochemical energy storage. Experimental characterization and molecular dynamics (MD) simulations were employed to investigate the decomposition mechanisms and morphological transformations of CaCO 3 . The results indicated that a temperature of 1000 °C represents a critical threshold for accelerated decomposition. Scanning electron microscopy (SEM) revealed the development of pores and carbon-depletion zones, while sintering-induced pore closure was observed at 1200 °C. The introduction of pulse residence time promoted particle cracking and enhanced the decomposition kinetics. MD simulations further demonstrated that CaO shell thickness controls CO 2 release: a 4 Å shell partially inhibited desorption, whereas a 6 Å shell completely blocked gas escape. The diffusion coefficient of calcium atoms in dual-particle systems increased by 3.6 times at 1473 K. Correspondingly, the diffusion activation energy decreased to 42.8 kJ·mol –1 in dual-particle systems, which facilitated the rapid formation of sintering necks. The combined effects of temperature, pulse duration, and shell confinement were consistently demonstrated, establishing a mechanistic framework for optimizing decarbonization and material synthesis.