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

Abstract

The present paper addresses the interaction of CO₂ with polycrystalline α-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 (A₂ = 3.01 × 10⁵ mol (m² s)⁻¹, E₂(0) = 112.8 kJ mol⁻¹, α₂ = 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 (A₁ = 0.0192 m s⁻¹, E₁ = 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 (Δ_adsH(250 °C) = −129 kJ mol⁻¹) as well as literature data.