Spillover controlled catalytic processes: from the atomic scale to macroscopic kinetics

This contribution is an attempt to outline the potential of the remote control (RC) concept for predicting new effects and creating more accurate kinetic models in the fields of selective oxidation and hydrotreating reactions (HDS, HDN, hydrocracking, etc.). The experimental proofs of the RC phenomena will just be summarized, but consequences predicted by the concept will be outlined. There are, in particular, micrometer and nanometer scale modifications of catalyst surface morphology under the influence of spilt over oxygen. For the first time in selective oxidation, a mathematical model reflects in a self consistent, non empirical way the experimental results. This is based on the Mars-van Krevelen mechanism, but takes into account the change of the number of active sites due to RC. Concerning hydrotreating, some of the verified predictions will be mentioned and the importance for chemical engineering of kinetic concepts based on RC will be underlined. Both for oxidation (oxygen spillover) and hydrotreating (hydrogen spillover), the scientific aspects still to clarify will be mentioned. This contribution highlights the fact that spillover plays a considerable role in controlling the dynamic state of catalysts when they are involved in the catalytic process.