Oxidation and reduction kinetic of YBaCo4O7+δ and substituted oxygen carriers

kinetic analysis of ybaco4o7+δ, y0.95ti0.05baco4o7+δ and y0.15zr0.1dy0.75baco4o7+δ oxygen carriers for clas system has been performed with tg data. the materials are characterized with xrd for phase composition, sem for particle morphology, and temperature-programmed thermogravimetry for oxidation and reduction reaction analysis. tg experiments are conducted with heating rates of 0.5, 1, and 2 k min−1 in thermal analyzer. the model-fitting approaches, li chung-hsiung and malek method, are used to estimate the most probable mechanism function. different processes have different models, for the oxidation process, a1 is selected as the most probable mechanism function for the all samples under different heating rates. and for reduction process, a2/3 is selected as the most probable mechanism function for all samples under different heating rates. that is, nuclei and nuclei growth or their combination are the rate-determining step. in mechanism, activation energy e and pre-exponential factor a are obtained. and the obtained kinetic parameters can reasonably express the oxidation and reduction process.