Atypical hydrogenation selectivity of platinum by reactive environment modulation

Abstract

Controlling selectivity in the hydrogenation of compounds with several functional groups remains a challenging task in heterogeneous catalysis. We report herein the design and use of simple catalysts composed of Pt nanoparticles confined in Silicalite-1 (S-1, MFI type zeolite) for the inversion of the inherent CO selective hydrogenation of cinnamaldehyde over Pt. The encapsulated catalyst achieved an unconventional 98% hydrocinnamaldehyde selectivity at high conversion levels (88%), which bypasses the inherent selectivity of Pt for CO versus CC hydrogenation. This high selectivity originates from the combination of the low polarity of the S-1 support and the toluene solvent that favor interaction of the catalyst with the CC over the CO group, and to the efficient encapsulation of the platinum in the zeolite channels which restricts the growth of the nanoparticles and consequently decreases the number of undesirable Pt(111) facets active for CO hydrogenation.