Breaking the Activity-Selectivity Trade-Off of Pt Nanoparticles Encapsulated in UiO-66 for Hydrogenation by Constructing Suitable Hierarchical Structure

The simultaneous enhancement of activity and selectivity during hydrogenation is a great challenge. Herein, by encapsulating Pt nanoparticles (NPs) into the hierarchical defective metal-organic framework (MOF) of UiO-66, the steric screening effect of the pores, Lewis acid sites of the nodes, and metal-MOF synergy have been finely tuned and effectively utilized for selective hydrogenation. Benefiting from optimal meso/micropores, favorable Lewis acid sites and strengthened metal-support interaction, Pt NPs encapsulated in hierarchical UiO-66 exhibited superior performance in selective hydrogenation. With the proper loading of Pt NPs into suitable meso/microporous UiO-66, the conversion of cinnamaldehyde is increased from 18.2% to 85% along with the selectivity for cinnamyl alcohol being improved from 15.8% to 76% under 70 degrees C and 2 MPa. The conventional trade-off relationship between increasing selectivity and promoting activity for encapsulated metal catalysts has been broken with the as-developed catalyst. This study provides a promising strategy to optimize transformation efficiency by the design of a tailored MOF-based framework for encapsulating metal NPs with the needed steric effect and synergistic effect.