New hybrid materials based on the grafting of Pd(ii)-amino complexes on the graphitic surface of AC: preparation, structures and catalytic properties

Abstract

2 S-F/Pd(II) hybrids on the hydrogenation of 1-octene in methanol as a catalytic test were evaluated. 100 % conversion to n-octane at T = 323.1 K and P = 15 bar, was obtained with both catalysts and most of Pd(II) was reduced to Pd(0) nanoparticles, which remained on the AC surface. Reusing of the catalysts in three additional cycles reveals that the catalyst bearing the F ligand with larger Pd-complexing ability showed no loss of activity (100 % conversion to n-octane) which is assigned to its larger structural stability. The catalyst with the weaker F ligand underwent progressive loss of activity (from 100 % to 79 % in four cycles), due to the constant aggregation of the Pd (0) nanoparticles. Milder conditions, T = 303.1 K and P =1.5 bar, prevent the aggregation of the Pd(0) nanoparticles in this catalyst allowing the retaining of high catalytic efficiency (100 % conversion) in four reaction cycles.

Multi-Walled Carbon Nanotubes Supported Pd(II) Complexes: A Supramolecular Approach towards Single-Ion Oxygen Reduction Reaction Catalysts

“…The preparation of said materials has been performed according to reported procedures [24][25][26][27][28][29][30]34]. In brief, MWCNTs (graphitized, 99.9% C, outer diameter 8-15 nm, inner diameter 3-5 nm, specific surface area 117 m 2 /g, NanoAmor, TX, USA) were put in contact with a 1.0 mM aqueous solution of the ligand maintaining a 1 mg MWCNT/1 mL of solution ratio and gently shaken during three days.…”

“…We make use of supramolecular chemistry and supported metal complexes to achieve this type of catalyst, rather than doping strategies [24][25][26]. A smart modular design of organic ligands possessing a polyaminic macrocyclic unit for Pd(II) binding and a grafting unit for non-covalent spontaneous functionalization of graphitic surfaces (activated carbon, multi-walled carbon nanotubes (MWCNT), graphene), bridged by a spacer, allows for relatively easy preparation of heterogenous catalysts in mild conditions (water, r.t., air) [27][28][29][30].…”

A New Heterogeneous Catalyst Obtained via Supramolecular Decoration of Graphene with a Pd2+ Azamacrocyclic Complex

“…In this respect, some of us have recently shown that the 6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidine group can be profitably exploited for the non-covalent functionalization of carbon materials thanks to its ability to π-π stack irreversibly with arene centers [10]. Following this strategy, different ligands, herewith represented as Ar-S-F (Figure 1), were appended on activated carbon (AC) [11,12,13,14,15,16,17,18] and on multi-walled carbon nanotubes (MWCNT) [19,20,21] to obtain hybrid materials that were employed for the recovery of both metal cations [12,13,14,15,16,21] and anions [17,18] from aqueous media and for the preparation of Pd-catalysts with high efficiency towards oxygen reduction reactions in alkaline media [19], Cu-free Sonogashira cross coupling reactions [20] and hydrogenation processes [11].…”

Heterogenization of a Chiral Molecular Catalyst on a Carbon Support using Tryptophan as Anchor Molecule

“…Carbon materials have a high potential for this application as they can be prepared with a large variety of textural properties, surface chemistry and morphology [4,5,9,10] . This proposal is inspired by the AC/Ar‐S‐F systems developed by Godino‐Salido et al [11] . and López‐Garzón et al [12] .…”

“…Carbon materials have a high potential for this application as they can be prepared with a large variety of textural properties, surface chemistry and morphology. [4,5,9,10] This proposal is inspired by the AC/Ar-S-F systems developed by Godino-Salido et al [11] and López-Garzón et al [12] in which Ar is a planar heteroaromatic residue, modified with designed pendant functions (F) through a polymethylenic chain (S), and adsorbed on the surface of an activated carbon (AC) by πÀ π interactions. It has been reported that these interactions imply irreversible electron donation from the carbon surface to a vacant π orbital of the molecule.…”