Synthesis and Catalytic Properties of Nanoparticulate Intermetallic Ga–Pd Compounds

Abstract

A two-step synthesis for the preparation of single-phase and nanoparticulate GaPd and GaPd(2) by coreduction of ionic metal-precursors with LiHBEt(3) in THF without additional stabilizers is described. The coreduction leads initially to the formation of Pd nanoparticles followed by a Pd-mediated reduction of Ga(3+) on their surfaces, requiring an additional annealing step. The majority of the intermetallic particles have diameters of 3 and 7 nm for GaPd and GaPd(2), respectively, and unexpected narrow size distributions as determined by disk centrifuge measurements. The nanoparticles have been characterized by XRD, TEM, and chemical analysis to ensure the formation of the intermetallic compounds. Unsupported nanoparticles possess high catalytic activity while maintaining the excellent selectivity of the ground bulk materials in the semihydrogenation of acetylene. The activity could be further increased by depositing the particles on α-Al(2)O(3).

Formation and stability of an active PdZn nanoparticle catalyst on a hydrotalcite-based support for ethanol dehydrogenation

“…Indeed, when methane decomposes into coke, more hydrogen is produced, explaining the initial pulse responses observed in the TAP measurements. In subsequent pulses, the hydrogen production per pulse decreases, but still exceeds the amount expected based on reactions (1) and (2). During the first pulses, a rapid blockage of adjacent Pd sites occurs by coke via reactions (1) to (4).…”

“…[31][32][33][34][35][36] Wet incipient impregnation and incorporation of the active metals in the support appear to offer promising perspectives for implementation at a larger scale. 2,37,38 Indeed, incorporation of the active metals within the support via a one pot synthesis is an easy and reproducible route for bimetallic catalyst synthesis. For propane dehydrogenation into propene, incorporation of the active metals in a hydrotalcite-based support has already proven to yield superior catalysts when compared with wet incipient impregnation.…”

“…1 Quite often higher activities and selectivities are obtained. [2][3][4] The catalyst particle size may play a determining role in the ultimate performance as a result of a geometric effect. For certain reactions to occur, a well-defined configuration of atoms is required, the number of such active sites depending on the particle size.…”

A Ship-in-a-Bottle Strategy To Synthesize Encapsulated Intermetallic Nanoparticle Catalysts: Exemplified for Furfural Hydrogenation

“…6,7 Schaak et al reported the synthesis of a number of nanocrystalline intermetallic compounds using lowtemperature solution chemistry methods. 8−11 The use of organic stabilizers in their synthetic protocol provides limited protection against aggregation of the nanoparticles (NPs).…”

The Intermetalloid Cluster [(Cp*AlCu)6H4], Embedding a Cu6 Core Inside an Octahedral Al6 Shell: Molecular Models of Hume–Rothery Nanophases

“…The compounds 1 and 2 are the first examples for HumeRothery-type intermetallic molecular clusters approaching the limit for classification as "metalloid" M n R c (n = 12; c = 10; c < n). Hume-Rothery nanophases, for example, Fe 4 Al 13 , [20] PdGa, [21] and NiGa, [22] attracted attention as selective semihydrogenation catalysts of alkynes to alkenes (active site isolation concept). These findings suggest inexpensive and abundant alternatives for established but rare and precious noble metal catalysts (for example, Pt, [23] Pd, [24] Ru, [25] Rh, [26] or Au [27] ).…”