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

• Published in: RSC advances 2016-01, Vol.6 (63), p.58247-58259
• Main Authors: Luz Godino-Salido, M, Gutiérrez-Valero, María D, López-Garzón, Rafael, Arranz-Mascarós, Paloma, Santiago-Medina, Antonio, Melguizo, Manuel, Domingo-García, María, López-Garzón, F. Javier, Abdelkader-Fernández, Victor K, Salinas-Martínez de Lecea, Concepción, Román-Martínez, M. Carmen
• Format: Article
• Language: English
• Subjects: Agglomeration; Catalysis; Catalysts; Conversion; Grafting; Graphene; Nanoparticles; Surface chemistry
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c6ra08858a

A novel procedure for the preparation of solid Pd( ii )-based catalysts consisting of the anchorage of designed Pd( ii )-complexes on an activated carbon (AC) surface is reported. Two molecules of the Ar-S-F type (where Ar is a plane-pyrimidine moiety, F a Pd( ii )-ligand and S an aliphatic linker) differing in F, were grafted on AC by π-π stacking of the Ar moiety and the graphene planes of the AC, thus favouring the retaining of the metal-complexing ability of F. Adsorption of Pd( ii ) by the AC/Ar-S-F hybrids occurs via Pd( ii )-complexation by F. After deep characterization, the catalytic activities of the AC/Ar-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 the catalysts in three additional cycles reveals that the catalyst bearing the F ligand with a 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 a 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 retention of the high catalytic efficiency (100% conversion) in four reaction cycles. Two novel hybrid catalysts have been prepared by anchoring Pd( ii )-amino complexes on the graphitic surface of ACs and their catalytic activities on the 1-octene hydrogenation are presented.