MODELING OF THE KINETICS OF CHEMICALLY CONTROLLED DOUBLE SOLID GAS REACTIONS

The experimental isothermal kinetics of reduction by H2 of Co(II, III) oxides pure and doped with chromium are compared to the simulated kinetics of a double isothermal reaction under pure chemical control. The calculation of the simulated overall rate laws and fractional reactions is based on the convolution integral of the rate laws of the elementary reactions. The linear (shrinking unreacted core) and Erofeev's nucleation and growth laws are considered as elementary reaction kinetics. Otherwise unpredictable overall kinetics result from their combination. From their comparison with experiment it appears that varying the prereactional protocol (e.g. with a thermal pretreatment in vacuo) and increasing the chromium doping rate may affect the kinetics law and the kinetic constant of both elementary reactions.