The intrinsic thermal decomposition kinetics of SrCO3 by a nonisothermal technique

The kinetics of the decomposition of SrCO3 in argon to SrO and CO2 were studied in the temperature range 1000 to 1350 K. The thermal decomposition was followed simultaneously by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) during linear heating. By using a nonisothermal method, the complete rate expression was determined from a relatively small number of experimental runs. Shallow beds of fine synthetic powder as well as thin flakes of pressed powder were employed to obtain the kinetics of decomposition in the absence of heat-and mass-transfer effects. The thermal decomposition started at about 1000 K. The recommended rate expression for the SrCO3 decomposition is d alpha/dt = B.exp (- E/RT).(1 - alpha)(n) where alpha is the ratio between the actual weight change and the theoretical final weight change, d alpha/dt is the time derivative of alpha, B is a rate constant in s(-1), E is the activation energy in J.mol(-1), R is the gas constant in J.K-1.mol(-1), T is the temperature in kelvin, and n is a factor depending on the geometry of the particles. The activation energy, E, for the decomposition of SrCO3 was evaluated to be 210 kJ/mol. Curves of calculated alpha vs temperature agree well with the experimental results.