Heterogeneous Heck Catalysis with Palladium-Grafted Molecular Sieves

Abstract

The synthesis and characterization of palladium-grafted mesoporous MCM-41 material, designated Pd-TMS11, are described. The material is investigated for carbon−carbon coupling reactions (Heck catalysis) with activated and nonactivated aryl substrates. For the preparation of the new catalyst, a volatile organometallic precursor is reacted in the gas phase with the surface of the porous framework, generating a highly dispersed metal deposition. The ultrahigh surface area, the large pore opening, and the highly dispersed catalyst species in Pd-TMS11 material create one of the most active heterogeneous catalysts for Heck reactions.

Polymer-Supported Carbene Complexes of Palladium: Well-Defined, Air-Stable, Recyclable Catalysts for the Heck Reaction

“…In order to make the Heck reaction more attractive for industry, several heterogeneous variants have previously been presented. [19] An efficient example uses Pd 0 grafted MCM-41 material, [20] which is synthesized by vapor deposition of a volatile palladium complex onto the inside walls of the porous framework, followed by reduction. Other examples use nanostructured palladium clusters stabilized by propylene carbonate [21] or hydrophilic palladium complexes anchored in supported aqueous phases (glass-bead technology).…”

Pd/SiO2 catalysts: synthesis of Pd nanoparticles with the controlled size in mesoporous silicas

“…Work has been directed toward the synthesis of nanoparticles (nanowires) of the metals, such as palladium [20][21][22][23][24][25][26][27][28][29][30][31][32][33], platinum [8,20,[34][35][36][37][38][39][40], ruthenium [41][42][43][44][45][46][47], gold [48][49][50][51], silver [36,52], within the channels of mesoporous silicates, mainly, MCM-41. The metals were introduced into the support either directly during the mesoporous silicate synthesis, or by post-synthesis treatment.…”

“…However, in this case a relatively low ion-exchange capacity of the calcined support limits the metal loading, for example, by ∼1 wt.% for Pd [25][26][27]53]. Only few syntheses of size-controlled noble metal nanoparticles within the channels of mesoporous molecular sieves have been described [8,25,28,29,33]. No systematic investigation of the influence of the synthesis conditions (mesoporous support pre-treatment, metal loading, etc.)…”

Heterogeneous alkenylation of aromatics under oxygen

“…The liquid-phase and the solid catalyst were separated via filtration after 4 h of reaction. The further reaction progress in the filtrate was monitored [26].…”