EPOXIDATION OF OLEFINS WITH PDMS MEMBRANES CONTAINING ZEOLITE OCCLUDED MANGANESE DIIMINE COMPLEXES

A new composite catalyst for selective epoxidation of olefins with ter t-butyl hydroperoxide (tBHP) is reported. The catalyst contains mangan ese diimine complexes (cis-Mn bis-2,2'-Bipyridyl), occluded within a N aY zeolite, in turn incorporated in a polydimethylsiloxane membrane (c is-[Mn(bpy)(2)](2+)-NaY-PDMS). The three-step synthesis consists of a Mn2+ exchange of NaY, ligand sorption to form cis-[Mn(bpy)(2)](2+)-NaY and incorporation of the latter in a PDMS membrane. The major differe nces between [Mn(bpy)(2)](2+)-NaY as such and occluded in PDMS are obs erved in the sorption and catalytic characteristics. With the membrane system, the use of a solvent becomes obsolete. Whereas optimal cycloh exene oxidation with [Mn(bpy)(2)](2+)-NaY occurs with hydrogen peroxid e in acetone, tBuOOH proves to be a better oxidant for [Mn(bpy)(2)](2)-NaY-PDMS. The reactions in batch and fed-batch reactors are discusse d. A simple regeneration procedure, monitored by FT-IR spectroscopy is proposed.