Directing Effect of Metal–Organic Frameworks in Pt-Catalyzed Selective Hydrogenation of Unsaturated Aldehydes

The regulation of the adsorption mode of reactants on the surface of metal nanoparticles is an efficient strategy to improve the selectivity and activity in selective hydrogenations. Herein, we report the directing effect of the MOF in Pt/Ni-MOF catalyzed selective hydrogenation of unsaturated aldehydes (cinnamaldehyde as model substrate). Pt/Ni-MOF shows much higher activity and selectivity toward the C═C hydrogenation product than other Pt/M-MOF (M = Co, Mn, Mg, Zn, Cu) under identical conditions, which is owing to the directed adsorption of the C═C bond on Pt surface through the interaction of the C═O bond and Ni-MOF and low H2 spillover in Ni-MOF. Interestingly, the release of Ni nanoparticles from Ni-MOF-74 was unambiguously observed in the H2 reduction process of Pt&Ni/Ni-MOF-74 (Pt and Ni coexistence), further increasing the activity by promoting the H2 dissociation activity. DFT calculation results suggest that the preadsorption of the C═O group on Ni nodes cooperatively stabilized the C═C group on Pt nanoparticles (NPs), thereby promoting the selective hydrogenation of the C═C bond in cinnamaldehyde. This work reveals the importance of the directing effect of MOF for selective hydrogenation and provides a promising strategy to tune the catalytic performance of supported metal NPs.