SELECTIVE HYDROGENATION OF CINNAMALDEHYDE CONTROLLED BY HOST-GUEST INTERACTIONS IN BETA-ZEOLITE

Large Pt-particles encapsulated in beta zeolite were obtained by direct H-2-reduction of Pt-exchanged zeolite beta. This catalyst gives a high selectivity to unsaturated alcohol in cinnamaldehyde hydrogenation because the geometric constraints in micropores impose an adsorption of the molecule via the C=O group. When the zeolite is calcinated in O-2 before reduction, Pt-clusters of size less than or equal to 1nm are obtained in the micropores. A simultaneous hydrogenation of the C=C and C=O bonds occurs initially on the smaller clusters but the selectivity to unsaturated alcohol increases with time probably as a result of a coalescence of the smaller clusters into clusters filling the open space in the micropores.