Hydrogenations are an important class of reactions, yet obtaining high selectivity remains challenging for some of these. A prime example is the chemoselective hydrogenation of α,β-unsaturated aldehydes over platinum-based catalysts. A great example of these is the hydrogenation of cinnamaldehyde, a highly useful molecule. Its hydrogenation often results in a mixture of the C=C hydrogenated product (hydrocinnamaldehyde), the C=O hydrogenated product (cinnamyl alcohol), and the fully hydrogenated product (hydrocinnamyl alcohol). Until now there have only been a few Pt-based catalysts reported that are capable of selectively hydrogenating cinnamaldehyde to hydrocinnamaldehyde, and these are often quite complex.
In this presentation, the synthesis, characterization, and evaluation of Pt NPs confined in S-1 for the hydrogenation of cinnamaldehyde is discussed. These catalysts, either prepared through simple in-situ encapsulation or impregnation methods, achieve high selectivity (>95%) to hydrocinnamaldehyde even at high conversions (>80%).
Such high selectivity is made possible by beneficial support effects which enhances the favorable adsorption configurations, and the encapsulation of the platinum in the zeolite channels. Presumably by restricting the size of the Pt NPs and thus reducing the number of unfavorable Pt sites.