Pp. Knopsgerrits et al., EPOXIDATION OF OLEFINS WITH PDMS MEMBRANES CONTAINING ZEOLITE OCCLUDED MANGANESE DIIMINE COMPLEXES, Catalysis today, 32(1-4), 1996, pp. 63-70
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.