In situ surface dynamics in heterogeneous catalysis

During the former half of the last century the mechanism of heterogeneous catalysis had been studied, keeping the catalyst in a black box, and on the basis of the information outside of the black box, it was discussed just from mere conjectures. The author initiated a method to study directly the behavior of the working catalyst surface, looking into the inside of the black box by measuring adsorption on the working catalyst surface. In the same period many varieties of recent physical tools to study the solid surfaces have been developed and were applied to study the in situ dynamics of working catalyst surface. However, even if some chemisorbed species were observed on the working catalyst surface, it does not follow that they are reaction intermediates. A new dynamic approach to identify the dynamic behavior of each of the chemisorbed species under the reaction conditions, had been proposed by the author by use of “isotope jump method”, in which labeled species are replaced during the course of reaction to study the behavior of each of the adsorbed species under the reaction conditions. By using such new techniques we could not only identify the reaction path and the rate-determining step, but also new phenomena which are called “adsorption assisted processes” were discovered, It is, accordingly, hoped that by means of new nanotechnologies recently developed to study the behavior of single molecules on solid surfaces the nature of heterogeneous catalysis should make a remarkable advances on the basis of this in situ dynamic methods. In this review article emphasis has been put in the fundamental methods of dynamic approaches.