Differentiation of Pt−Fe and Pt−Ni₃ Surface Catalytic Mechanisms towards Contrasting Products in Chemoselective Hydrogenation of α,β‐Unsaturated Aldehydes

Abstract

Noble‐metal catalysts serve as an irreplaceable role in pharmaceutical, perfume and fine chemicals fields. However, there still remains a grand challenge in controlling chemoselectivity. Herein, we have synthesized a bimetallic nanostructure supported on porous metal‐organic frameworks (Pt−Fe/UiO‐66, Pt‐Ni3/UiO‐66), in which Pt nanoparticles was modified with non‐noble metal (Fe or Ni) directly. The as‐synthesized catalysts can function as a switch for selective hydrogenation of α,β‐unsaturated aldehydes to afford the potential products on‐demand. In comparison with the conventional Pt‐based catalysts, Pt−Fe/UiO‐66 and Pt‐Ni3/UiO‐66 catalysts exhibit excellently catalytic activity, enhanced selectivity and improved stability for selectivity hydrogenation. The partial charge reconfiguration and electronic coupling effect existing in such distinctive bicomponent nanocatalysts was confirmed by some comprehensive characterization and density functional theory (DFT) calculations. The developed method for precisely modification the composition and interaction between the noble metal and non‐noble metal provides a feasible avenue to design the advanced catalysts.

Citral Hydrogenation over Dilute Alloy Catalysts

“…Since our dilute alloy catalysts show no bulk NiPt phase and minimal evidence of charge transfer between Ni and Pt, this absence of selective C=O bond hydrogenation is in agreement with the previously reported results. It has also been reported that a Pt‐Ni 3 /UiO‐66 catalyst was primarily selective to the partially saturated aldehyde [10] . These results also support the hypothesis described above that the nanoparticle surface is predominantly Ni, as substantial Pt on the surface would be expected to change the selectivity as compared to Ni/SiO 2 .…”

“…It has also been reported that a Pt-Ni 3 /UiO-66 catalyst was primarily selective to the partially saturated aldehyde. [10] These results also support the hypothesis described above that the nanoparticle surface is predominantly Ni, as substantial Pt on the surface would be expected to change the selectivity as compared to Ni/SiO 2 . This is not expected to be the only adsorption mode for citral, however, as the unsaturated alcohol selectivity observed over Cu suggests some preferential C=O bond hydrogenation.…”

“…Then, by comparing Cu‐ and Ni‐based catalysts, we also aim to identify the role of the host metal in the observed performance. While monometallic Ni catalysts have been reported to be unselective to unsaturated alcohols and monometallic Pt catalysts to be moderately selective, [1a] NiPt catalysts have been reported to have improved selectivity, however NiPt single atom alloys have not been studied [10,14] . These selectivity trends have been rationalized in terms of the d‐band structure; the larger d‐band of Pt leads to stronger repulsive interactions with the C=C bond, thus lowering the probably of adsorption [1a] .…”

“…While monometallic Ni catalysts have been reported to be unselective to unsaturated alcohols and monometallic Pt catalysts to be moderately selective, [1a] NiPt catalysts have been reported to have improved selectivity, however NiPt single atom alloys have not been studied. [10,14] These selectivity trends have been rationalized in terms of the d-band structure; the larger d-band of Pt leads to stronger repulsive interactions with the C=C bond, thus lowering the probably of adsorption. [1a] In this work, we aim to determine how the required catalyst structure changes for the selective hydrogenation of bulkier molecules such as citral.…”

Rational Design of Pt−Pd−Ni Trimetallic Nanocatalysts for Room‐Temperature Benzaldehyde and Styrene Hydrogenation

“…The catalysts have gradually evolved from monometallic to multimetallic structures. Particularly, the multimetallic catalysts containing precious metals can significantly reduce the amount of the noble metals and simultaneously improve their catalytic performance (activity, selectivity and stability), due to synergetic effect among related species, [1–19] For instance, a small amount of Rh was added to a Pt‐based catalyst, forming a Pt−Rh bimetallic system, its stability for the catalytic oxidation of ammonia was markedly improved [20] . The Au/SiO 2 , Au/ZrO 2 , Au/TiO 2 , Au/ZnO monometallic and Au−In/ZnO bimetallic supported catalysts were prepared by Claus et al ., [21,22] and these catalysts were applied in selective hydrogenation of acrolein.…”