Microkinetic Simulation of Temperature-Programmed Desorption

Abstract

The temperature-programmed desorption (TPD) spectra were simulated by combining density functional theory (DFT) calculations and microkinetic modeling. In the microkinetic analyses, all kinetic and thermodynamic parameters were obtained from DFT calculations to minimize artificial assumptions. For the case study, the desorptions of NH 3 and H 2 O from the RuO 2 (110) surface were simulated. The coverage-dependent desorption energies were introduced into the microkinetic model because different adsorbates on the surface will exhibit different desorption behaviors. In addition, temperature-dependent pre-exponential factors were applied to the desorption rate equations. The calculated pre-exponential factors are ranged from 10 14 to 10 17 s –1, which are greatly larger than 10 13 s –1, a generally accepted empirical value for desorption processes. The desorption temperatures obtained from microkinetic simulations consist with experimental results, and the simulated TPD patterns are also similar to the experimental observations.