Influence of experimental conditions on the kinetic parameters of gas-solid reactions - Parametric sensitivity of thermal analysis

Article abstract of DOI:10.1016/0040-6031(96)02882-1

The influence of experimental conditions on the kinetic parameters of gas-solid reactions has been investigated using the reduction of nickel oxide by hydrogen as a model reaction. The experimental parameters studied were heating rate, sample mass, total gas flow and hydrogen concentration. For arbitrarily chosen standard conditions the kinetic parameters best describing the course of the reaction were calculated using the global curves analysis method. Experiments were carried out with different heating rates, in the range 1.3-10.6 K min^-1. Twenty two kinetic models of solid-state reactions proposed in the literature were tested using numeric integration methods. The confidence space, in which the kinetic parameters, calculated for standard conditions , fit the kinetics of NiO reduction properly, was calculated taking into account the influence of all investigated variables. The results illustrate the great influence of the experimental conditions on the measured thermoanalytic curves ( parametric sensitivity ) and demonstrate the limited validity of kinetic data calculated from experiments carried out under arbitrary chosen conditions.