Zeolite-immobilized Mn(III), Fe(III) and Co(III) complexes with 5,10,15,20-tetra(4-methoxyphenyl)porphyrin as heterogeneous catalysts for the epoxidation of (R)-(+)-limonene: synthesis, characterization and catalytic activity

Nanodimensional pores of metal-exchanged zeolite Y containing 5,10,15,20-tetra(4-methoxyphenyl)porphyrin have been prepared by the template "ship-in-a-bottle" method. This approach requires four pyrrole molecules and four 4-methoxy benzaldehyde molecules to diffuse into the pores of Fe-III, Mn-III and Co-III-exchanged zeolite Y. The host-guest nanocomposite materials have been applied to catalyze the epoxidation of (R)-(+)-limonene, using H2O2/ammonium acetate, at a defined temperature and atmospheric pressure. The encapsulated iron(III) complex is catalytically very efficient as compared to manganese(III) and cobalt(III) complexes for the partial epoxidation of (R)-(+)-limonene and is stable to be recycled without much deterioration. All catalytic systems have been characterized by UV/Vis diffuse reflectance spectroscopic, X-ray diffraction, BET, scanning electron microscopy and energy dispersive X-ray spectrometry analyses to confirm the immobilization of complexes.