Grafting nanometer metal/oxide interface towards enhanced low-temperature acetylene semi-hydrogenation

Abstract

Metal/oxide interface is of fundamental significance to heterogeneous catalysis because the seemingly “inert” oxide support can modulate the morphology, atomic and electronic structures of the metal catalyst through the interface. The interfacial effects are well studied over a bulk oxide support but remain elusive for nanometer-sized systems like clusters, arising from the challenges associated with chemical synthesis and structural elucidation of such hybrid clusters. We hereby demonstrate the essential catalytic roles of a nanometer metal/oxide interface constructed by a hybrid Pd/Bi2O3 cluster ensemble, which is fabricated by a facile stepwise photochemical method. The Pd/Bi2O3 cluster, of which the hybrid structure is elucidated by combined electron microscopy and microanalysis, features a small Pd-Pd coordination number and more importantly a Pd-Bi spatial correlation ascribed to the heterografting between Pd and Bi terminated Bi2O3 clusters. The intra-cluster electron transfer towards Pd across the as-formed nanometer metal/oxide interface significantly weakens the ethylene adsorption without compromising the hydrogen activation. As a result, a 91% selectivity of ethylene and 90% conversion of acetylene can be achieved in a front-end hydrogenation process with a temperature as low as 44 °C.

Enhanced acetylene semi-hydrogenation on a subsurface carbon tailored Ni–Ga intermetallic catalyst

“…8,17,18 However, the adsorption modes for acetylene and ethylene are still σ-adsorption for Ni-/Pd-based intermetallic catalysts with partially isolated Ni/Pd active sites. 2,5–8,16–25 These features give rise to unfavorable selectivity to ethylene but relatively higher hydrogenation activity in comparison with the intermetallic catalysts with completely isolated Ni/Pd sites. An interesting challenge that arises is addressing the possibility of further optimizing the adsorption/desorption behaviors of ethylene on such partially isolated active sites toward excellent ethylene selectivity, which could also maintain the relatively higher activity than the completely isolated active sites.…”

Alloyed PdCu Nanoparticles within Siliceous Zeolite Crystals for Catalytic Semihydrogenation

“…These features result in PdCu/S-1 being more active than PdCu@S-1. In addition, the C 2 H 4 selectivity of PdCu/S-1 is higher than 90% with C 2 H 2 conversion below 70%, but the selectivity was rapidly decreased with increasing C 2 H 2 conversion (Figure and Supporting Information Figure S10 and Table S1), which follows the scaling relationship. , This feature should be assigned to the strong adsorption of C 2 H 4 on the Pd surface that accelerates the overhydrogenation to form C 2 H 6 , which is consistent with those of previous reports. − …”

Bismuth-Modulated Surface Structural Evolution of Pd3Bi Intermetallic Alloy Catalysts for Selective Propane Dehydrogenation and Acetylene Semihydrogenation

“…The possible IMCs for any two metals can be determined from the phase diagrams. 55 Since catalytic alloys are formed kinetically, that is, by reduction of the metal salts, rather than thermodynamically, for example, slow cooling of a binary metallic liquid, not all IMCs are formed. The group 8 metal is first reduced.…”