Kinetic model of the temperature-programmed desorption of ammonia to study the acidity of heterogeneous catalysts

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 are proposed. This method uses the Polanyi-Wigner kinetic model with formal kinetics approaches for simple reactions, which imposes restrictions on the observed orders of 1, 2, or 3. The parameters of TPD curves are selected based on the inverse simulation using the Runge-Kutta method and fitting them to experimental points using dynamic model parameters changes. As an example, several heterogeneous catalysts are presented in this work. TPD-NH3 of titanium silicalite-1 and silicalite-1 is obtained using one third-order desorption kinetic equation. TPD-NH3 of the three samples of γ-alumina is obtained using two desorption peaks with similar kinetic parameters.