Structure of Catalytic Active Sites of Fluorided Alumina Catalystt

Abstract

The structure of catalytic active sites of fluorided alumina catalyst was studied by the methods of X-ray diffraction and 11-1 and 19F broad line NMR. X-ray diffraction analysis found no structural difference between 77-alumina and fluorided alumina, in spite of a remarkable difference in catalytic activities between them. However, the 111 and "F broad line NMR showed that the structural difference between them and that the structural positions of 'H and "F nuclei in the catalyst were localized near the surface of the catalyst particles. These results suggest that the catalytic active sites consist of five different types formed from different number of coordinated F and 0 atoms. The role of these active sites on the catalytic reactions was studied in cumene cracking, o-xylene isomerization and toluene disproportionation reactions over the fluorided alumina.