PdZn Intermetallic Nanostructure with Pd–Zn–Pd Ensembles for Highly Active and Chemoselective Semi-Hydrogenation of Acetylene

Abstract

Intermetallic alloying of one active metal to another inert metal provides not only the improved dispersion of active centers but also a unique and homogeneous ensemble of active sites, thus offering new opportunities in a variety of reactions. Herein, we report that PdZn intermetallic nanostructure with Pd–Zn–Pd ensembles are both highly active and selective for the semihydrogenation of acetylene to ethylene, which is usually inaccessible due to the sequential hydrogenation to ethane. Microcalorimetric measurements and density functional theory calculations demonstrate that the appropriate spatial arrangement of Pd sites in the Pd–Zn–Pd ensembles of the PdZn alloy leads to the moderate σ-bonding mode for acetylene with two neighboring Pd sites while the weak π-bonding pattern of ethylene adsorption on the single Pd site, which facilitates the chemisorption toward acetylene and promotes the desorption of ethylene from the catalyst surface. As a result, it leads to the kinetic favor of the selective conversion of acetylene to ethylene.

Selective Semihydrogenation of Phenylacetylene to Styrene Catalyzed by Alloyed Palladium/Gold Catalysts Anchored on Cerium Oxide

“…As shown in Figure S8, all alloyed PdAu catalysts delivered the higher activity compared with that of Pd or Au catalysts alone. This phenomenon of the PdAu alloyed catalysts with the improved hydrogenation activity was also observed in previous reports ,,,. With the increase Pd contents, the conversions of phenylacetylene were slightly increased form 43.3% to 49.5% for the alloy PdAu catalysts (Figure S8).…”

“…One viable approach to realize the selectively semi‐hydrogenated alkynes is to use bimetallic catalysts that combines the catalytically active metals with the second metals . Pd‐based catalysts modified by a second metal (e. g., Zn, Au, Ag, Pb, Cu) have been widely explored for the chemoselective semi‐hydrogenation of alkynes ,. This strategy with the controllable compositions of the alloyed metal catalysts can retain the high activity of Pd and increase catalytic selectivity at the same time.…”

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdHx

“…Intermetallic materials with well‐defined structures and tunable compositions afford unique catalytic properties, and are thus highly desirable for heterogeneous catalysis . For instance, L1 0 ‐type PdZn with lattice parameters of a = b =4.0915 Å and c =3.3426 Å in space group P 4/ mmm , is regarded as a promising catalyst for methanol steam reforming (MSR), the water–gas shift reaction (WGS), alkane dehydrogenation, and selective hydrogenation reactions . The excellent catalytic performance of intermetallic PdZn is derived from reduction of the ZnO‐supported Pd, which give rise to unique electronic properties and structural stability.…”

Enhanced catalytic performance of Pd‐Ga bimetallic catalysts for 2‐ethylanthraquinone hydrogenation

“…Notably, with the incorporation of Ga, a slight red shift of the linear bond peak and the bridge bond peak is observed for 0.6Pd1.2Ga catalyst, which may result from strong electronic effects of Ga 2 O 3 on Pd nanoparticles. Similar results have suggested that electronic effects of Ga 2 O 3 on Pd leads to an increase of d‐orbital electron density of Pd, which exhibits a red shift in CO‐DRIFTS . To further confirm the electronic interaction between Ga and Pd species, XPS was conducted to investigate the chemical states of Pd and Ga species.…”