Pyrolysis kinetics of manganese carbonate

In this study, to better control the morphology of Mn3O4 prepared by roasting micron-sized spherical MnCO3, the pyrolysis kinetics of MnCO3 was investigated by measuring the thermogravimetry (TG) curves under different heating rates in air, and the pyrolysis kinetic mechanism function of MnCO3 was also calculated. The TG results showed that the pyrolysis of MnCO3 can be mainly divided into two stages, and the corresponding temperature range was 300-500 degrees C and 840-900 degrees C, respectively. The kinetics results showed that the activation energies of the two reaction stages of MnCO3 calculated using FWO method, KAS method, and Starink method were 315.13, 317.41, 318.54 kJ mol(-1), and 1456.70, 1454.19, 1456.08 kJ mol(-1), respectively. The kinetics mechanism models of two stages were determined as random nucleation and subsequent growth model using the master plot method, and the corresponding kinetic mechanism functions were G(alpha) = [- ln(1 - alpha)](3/2) and G(alpha) = [- ln(1 - alpha)](3/4), respectively. In addition, the mechanism function analysis results showed that an increase in the heating rate slightly affected the temperature difference (Delta T) for the completion of the reaction at each stage, which would have a different effect on the morphology of the product. The roasting experiment results confirmed the above theoretical conclusions.

Automated summary

This study investigates the pyrolysis kinetics of MnCO3 to control the morphology of Mn3O4 and calculates the corresponding kinetic mechanism function. The results show that pyrolysis of MnCO3 can be divided into two stages within different temperature ranges. The activation energies of the two reaction stages are calculated using different methods. The mechanism function analysis indicates that the heating rate has a slight effect on the temperature difference for reaction completion, which affects the morphology of the product.