The state of platinum in high-silica zeolites and its catalytic activity in ethane and propane aromatization

The catalytic properties of Pt-containing high-silica zeolites in the aromatization of lower alkanes and the XPS spectra of these catalysts have been investigated. Both the electronic states of Pt and catalytic activity depended strongly on the pre-treatment conditions and changed in the course of the reaction. The development of the catalytic activity observed during successive catalytic runs in the pulse mode was accompanied by an increase in positive charge on highly dispersed metallic clusters located in the vicinity of acidic OH groups of zeolite. The Ptγ + centres in combination with acidic sites are likely to be responsible for ethane and propane transformations into aromatics over Pt-containing-high silica zeolites.