Kinetic modeling of the adsorption and desorption of CO2 on α-Fe2O3

The present paper addresses the interaction of CO2 with polycrystalline alpha-Fe2O3 revealing considerable catalytic activity in CO oxidation to yield CO2. The mechanism of adsorption and desorption of CO2 was investigated by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), while the kinetics was examined by temperature-programmed desorption (CO2-TPD). For numeric modeling as well as simulation of the surface coverage, an elementary kinetic mean field model was constructed using Arrhenius-based rate expressions. The kinetic parameters of desorption were taken from fitting calculations (A(2) = 3.01 x 10(5) mol (m(2) s)(-1), E-2(0) = 112.8 kJ mol(-1), alpha(2) = 70.2 kJ mol(-1)), whereas the adsorption was considered to be non-activated and the pre-exponential factor was estimated from kinetic gas theory (A(1) = 0.0192 m s(-1), E-1 = 0 kJ mol(-1)). For model validation, predicted and experimental CO2-TPD profiles were compared and thermodynamic consistency was evaluated by using differential scanning calorimetry (Delta H-ads(250 degrees C) = -129 kJ mol(-1)) as well as literature data.