Kinetic Model of the Temperature-Programmed Desorption of Ammonia to Study the Acidity of Heterogeneous Catalysts

Abstract

A new method for processing the results of the temperature-programmed desorption (TPD) of ammonia from heterogeneous catalyst surfaces and an approach for automatic deconvolution of TPD kinetic curves were proposed. This method uses the Polanyi–Wigner kinetic model with formal kinetics approaches for simple reactions, which imposes restrictions on the observed first, second, or third orders. The parameters of the TPD curves were selected based on the inverse simulation using the Runge–Kutta method and fitting them to experimental points using dynamic model parameter changes. As an example, several heterogeneous catalysts were presented in this work. TPD-NH₃ of titanium silicalite-1 and silicalite-1 was obtained using one third-order desorption kinetic equation. TPD-NH₃ of three γ-alumina samples was obtained using two desorption peaks with similar kinetic parameters.