In Situ Encapsulation of Pt Nanoparticles within Pure-Silica TON Zeolite for Space-Confined Selective Hydrogenation

Straightforward encapsulation of Pt clusters (∼2 nm) into the pure silica TON type zeolite (ZSM-22) was reached in a dry-gel-conversion route, where the ionic liquid template was removed via the hydrocracking-calcination-reduction approach. The obtained Pt@ZSM-22 series possessed high crystallinity, large surface area and ultra-fine Pt clusters inside the zeolite crystals. They exhibited remarkable activity in the semi-hydrogenation of phenylacetylene into styrene; the lead sample with 0.2 wt% Pt loading afforded a large turnover number up to 117787. The preferentially high affinity of the pure silica ZSM-22 encapsulated Pt clusters towards the substrate phenylacetylene rather than the hydrogenated product was derived from the unique space-confinement effect of zeolite microchannels, which is responsible for such excellent performance.