Microkinetic analysis of temperature-programmed experiments in a microreactor flow system

Temperature-programmed (TP) experiments provide useful information about the kinetic properties of adsorbates. The TP experiments can be carried out either in ultra-high vacuum (UHV) or at ambient pressure using flow set-ups. Thus, they can serve as a tool to bridge the material and pressure gap between surface science and heterogeneous catalysis by applying microkinetic analysis. The temperature-programmed desorption (TPD) of H₂ from Cu is used as an example to discuss the derivation of kinetic parameters from measurements in UHV. N₂ TPD experiments from a multiply promoted Fe catalyst are analyzed to demonstrate that the assessed influence of readsorption effects depends on the reactor model chosen. The transient continuous-flow stirred tank reactor (CSTR) and the transient plug-flow reactor (PFR) are used for the modeling. Finally, the temperature-programmed surface reaction (TPSR) of adsorbed atomic nitrogen with H₂ yielding NH₃ over Fe- and Ru-based catalysts is re-examined to illustrate the influence of the reactor model.