Isolated Single-Atom Pd Sites in Intermetallic Nanostructures: High Catalytic Selectivity for Semihydrogenation of Alkynes

Abstract

Improving the catalytic selectivity of Pd catalysts is of key importance for various industrial processes and remains a challenge so far. Given the unique properties of single-atom catalysts, isolating contiguous Pd atoms into a single-Pd site with another metal to form intermetallic structures is an effective way to endow Pd with high catalytic selectivity and to stabilize the single site with the intermetallic structures. Based on density functional theory modeling, we demonstrate that the (110) surface of Pm3̅m PdIn with single-atom Pd sites shows high selectivity for semihydrogenation of acetylene, whereas the (111) surface of P4/mmm PdIn with Pd trimer sites shows low selectivity. This idea has been further validated by experimental results that intermetallic PdIn nanocrystals mainly exposing the (110) surface exhibit much higher selectivity for acetylene hydrogenation than PdIn nanocrystals mainly exposing the (111) surface (92% vs 21% ethylene selectivity at 90 °C). This work provides insight for rational design of bimetallic metal catalysts with specific catalytic properties.

Isolated Fe Single Atomic Sites Anchored on Highly Steady Hollow Graphene Nanospheres as an Efficient Electrocatalyst for the Oxygen Reduction Reaction

“…[11,12] In spite of the controversial identifications of active sites for Fe-N x -based carbon catalysts in scientific community, there comes a consensus in catalysis that the reactivity would be remarkably improved by downsizing the catalyst to increase the number of active sites. [17][18][19][20] Nevertheless, the fabrication of ISA catalysts remains a grand challenge due to the very high surface energy, easy migration, and serious aggregation of ISAs during catalytic reaction. [17][18][19][20] Nevertheless, the fabrication of ISA catalysts remains a grand challenge due to the very high surface energy, easy migration, and serious aggregation of ISAs during catalytic reaction.…”

Polymer‐Assisted Co‐Assembly towards Synthesis of Mesoporous Titania Encapsulated Monodisperse PdAu for Highly Selective Hydrogenation of Phenylacetylene

“…For PdAu nanoalloys, the changes of geometric distribution of Pd greatly favors weak π adsorption of alkynes. The desorption of alkenes is energetically favorable instead of full hydrogenation into ethylbenzene . This accounts for the high selectivity to styrene over PdAu@mTiO 2 .…”

Reduction of phenylacetylenes using Raney Ni–Al alloy, Al powder in the presence of noble metal catalysts in water

“…The reaction does not also produce any harmful by-products. The only by-product is Al(OH) 3 , which is a non-toxic and an easily recyclable material. The reaction does not require a high pressure of hydrogen, which is advantageous given the explosive nature of hydrogen that also requires the use of high pressure reaction vessels.…”

“…2 Nowadays, isolated single atom Pd sites in intermetallic nanostructures are used for high catalytic selectivity in the semihydrogenation of alkynes and light mediated preparation of palladium nanoparticles as catalysts for alkyne cis-semihydrogenation. 3,4 It is found that N,N-dimethylformamide (DMF) can act as a hydride source in nickel-catalyzed asymmetric hydrogenation of α,β-unsaturated esters. 5 Also a Hantzsch amido dihydropyridine has been reported as a transfer hydrogenation reagent for α,β-unsaturated ketones while pyridine derivatives were reduced via borane-catalyzed transfer hydrogenation reaction with ammoniaborane.…”