Polymer versus phosphine stabilized Rh nanoparticles as components of supported catalysts: implication in the hydrogenation of cyclohexene model molecule

Abstract

Graphical abstractInfluence of stabilizers on the catalytic performance of small rhodium nanoparticles was studied through a model hydrogenation reaction. properties of these nanoparticles were compared using a model catalysis reaction namely, hydrogenation of cyclohexene, first in colloidal conditions and then in supported conditions after their immobilization onto an amino functionalized silica-coated magnetite support. PVP-stabilized Rh NPs were the most active catalyst whatever the catalytic conditions as the result of a strong coordination of the phosphine ligands at the metal surface that blocks some surface atoms even after several recycles of the supported nanocatalysts and limit the reactivity of the metallic surface. Key-words

Rhodium nanoparticles stabilized by ferrocenyl-phosphine ligands: synthesis and catalytic styrene hydrogenation

“…The first objective of this work was to take benefit of previous results in the organometallic synthesis of phosphine-stabilized rhodium nanoparticles, achieved from the [Rh( 3 -C3H5)3] complex as metal source and simple mono-or di-substituted phosphines as stabilizers, 26,28 in order to prepare a new family of Rh NPs by the same approach but using ferrocenyl phosphines. With ferrocene-based-phosphine-capped Rh NPs in hands, a second objective was to test their catalytic activity in a benchmark hydrogenation process, the hydrogenation of styrene, in order to evaluate the influence of the capping ligands at the rhodium surface.…”

“…1.3 nm). 26 For comparison, the bidentate Ph2P-(CH2)4-PPh2 ligand led to stable Rh NPs at a [ligand]/[Rh] ratio of 0.3 molar equivalent, which amounts to a [donor]/[Rh] ratio of 0.6. Consequently, the bidendate phosphino-ferrocenyl ligands used here behave as efficient stabilizers at lower [ligand]/[Rh] ratios compared to the previously studied similar mono-and diphosphane ligands.…”

“…The isolated particles displayed crystalline regions with interplanar distances of 0.22 nm, in good agreement with the fcc structure (face-centered cubic) previously observed for similarly made Rh nanoparticles and for bulk rhodium. 26 In the case of L5-stabilized Rh NPs no agglomerates were observed besides isolated NPs. These latter were poorly crystallized with only a few of them displaying crystalline plans.…”

“…22 Rhodium particles can also be synthesized by the organometallic method, starting from [Rh(acac)(1,5-C8H12)], 23 [Rh(µCl)(1,5-C8H12)]2 24 , or [Rh( 3 -C3H5)3]. 25 Phosphines ligands were shown to affect the reactivity of Rh NPs in hydrogenation 26,27 and hydroformylation catalysis. 28 Apart from usual ligands to stabilize metal NPs, one can envisage to use metalcontaining ligands.…”

Separation technology meets green chemistry: development of magnetically recoverable catalyst supports containing silica, ceria, and titania

“…This method was chosen due to the high quality of the magnetic materials -spherically coated with silica -obtained with this methodology. We have been using this material as a catalyst support for metal nanoparticles [2,[12][13][14][15][16][17][18], metal complexes [19], and enzymes [20,21] to perform a large scope of reactions. All the reactions have been performed at relatively mild conditions (<373 K) because the stability of the Fe 3 O 4 @SiO 2 material upon thermal treatment has never been studied in detail.…”