Investigations on Kinetics and Mechanisms of CaCO3 Calcination in Calcium Looping

• Published in: Industrial & engineering chemistry research 2023-03, Vol.62 (12), p.4851-4863
• Main Authors: Li, Zeya, Guo, Xiaojin, Xue, Xiaoyong, Xu, Xiang, Wang, Bo
• Format: Article
• Language: English
• Subjects: Kinetics, Catalysis, and Reaction Engineering
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.2c03314

Calcium looping-based CO2 capture is generally considered more efficient than conventional postcombustion CO2 capture. Calcium carriers’ calcination in the regenerator is crucial because proper operating parameters can provide regenerated carriers suitable for the gasifier and prevent sintering. This work focuses on the calcination behavior of CaCO3 in calcium looping systems. In this study, the calcination kinetic parameters under various conditions were investigated using a model-free isoconversional method based on nonisothermal thermogravimetric analysis in a macroscope, in combination with X-ray diffraction tests of the samples in a microscope. Results in the macroscope showed that the apparent activation energy ranges from 121.8 to 163.0 kJ/mol under a conversion range of 0.3–0.9, and the CaCO3 calcination mechanism involves transient nucleation and two-dimensional growth. Results observed from the microscope demonstrated that CaCO3 tends to be calcined on a plane, consistent with the macroscope model with two-dimensional nucleation. Since the microscopic mechanism is reflected, the kinetic model can be widely adopted, and calcium-based carrier modification strategies can also be proposed to prevent sintering of the carrier perpendicular to the (1̅04) plane.