Benzene Formation at 70 °C by Coupling of Propylene on Supported Pd Nanoclusters

Abstract

Reactions on supported transition metal clusters have important applications and often display unexpected reactivity when the cluster size is on the nanometer scale.[1] As reliable methods of preparing size-selected supported clusters have been developed, relationships between the preparation method, size, and/or support have become apparent, albeit poorly understood. Metal clusters can be synthesized by using micelle encapsulation, and this method has been further developed to make nanocluster powders supported on metal oxides.[2-4] The metal ions are initially dissolved homogeneously within the hydrophilic block copolymer cores of the micelle solutions, and the length and structure of the copolymers can be used to control the sizes of the clusters.

Nanometric Pd-confined mesoporous silica as high-efficient catalyst for toluene low temperature removal: Effects of support morphology and textural property

“…As is known, the small particle size as well as the high surface area of the Pd nanoparticles is often unstable at elevated reaction temperatures [13][14][15]. Researchers found that the pore channels of mesoporous supports have the potential ability to inhibit active particles growth and aggregation during reactions [7,16].…”

Covalently Linked Bis(Amido‐Corroles): Inter‐ and Intramolecular Hydrogen‐Bond‐Driven Supramolecular Assembly

“…This is strongly related to the ability of −NHCO− to act simultaneously as hydrogen‐bond donor and acceptor. These structures include helices, zig‐zags, antiparallel β‐strands, tapes, macrocycles, cryptands, capsules, Janus‐dendrimers, and molecular electrets . Clearly, this ability has been utilized by nature to form three‐dimensional peptide and protein secondary structures .…”

“…[12] The presence of multiple secondary amide groups in organic molecules has been provent ob earobustw ay of increasing the propensity for said molecule to self-assemble into reprodu-cible secondary structures.T his is strongly related to the ability of ÀNHCOÀ to act simultaneously as hydrogen-bond donor and acceptor. These structures include helices, [13] zig-zags, [14] antiparallel b-strands, [15] tapes, [16] macrocycles, [17] cryptands, [18] capsules, [19] Janus-dendrimers, [20] and molecular electrets. [21] Clearly,this ability has been utilized by naturet oformthree-dimensional peptide and protein secondary structures.…”

Highly Active and Sinter‐Resistant Pd‐Nanoparticle Catalysts Encapsulated in Silica

“…Pd‐based heterogeneous catalysts have been used in a wide range of important chemical processes including CO oxidation,1, 2 aerobic alcohol oxidation,3 NO x reduction,4 conversions of volatile organic compounds,5, 6 hydrogenation,7–9 and dehydrogenation 10. Recent work has suggested that when the dimensions of the Pd particles are reduced to less than 10 nm the catalysts are extraordinarily active and may exhibit unique properties 11–14. Unfortunately, Pd as well as other metal nanoparticulate catalysts are often unstable with respect to sintering on oxide supports at elevated reaction temperatures and their activity rapidly decays 15–19…”

“…[10] Recent work has suggested that when the dimensions of the Pd particles are reduced to less than 10 nm the catalysts are extraordinarily active and may exhibit unique properties. [11][12][13][14] Unfortunately, Pd as well as other metal nanoparticulate catalysts are often unstable with respect to sintering on oxide supports at elevated reaction temperatures and their activity rapidly decays. [15][16][17][18][19] To stabilize nanoparticulate metals, unique structures consisting of metal cores surrounded by oxide, carbon, or other metal shells (core/shell) have been created.…”