New insights into the spatial distribution of aluminium in various mesoporous aluminosilicates.

Abstract

Outside the wall: The spatial distribution of framework Al on mesoporous aluminosilicates (MAS) was probed with a simple tool, the oxidation of cyclohexene over metal (Mn) porphyrins supported on MASs. The porphyrins are bound on framework Al sites and therefore their selectivity can be related to the location of Al. Porphyrins bound on the external surface catalyse both allylic oxidation and epoxidation of cyclohexene whereas those bound internally (on pore wall surfaces) can only catalyse allylic oxidation. The picture shows the selectivity pattern over Al-MCM-41 and Al-HMS/Al-MMS supported catalysts and indicates a crucial difference in the spatial distribution of framework Al in these MAS.