A comparison between silica-immobilized ruthenium(II) single sites and silica-supported ruthenium nanoparticles in the catalytic hydrogenation of model hetero- and polyaromatics contained in raw oil materials

• Published in: Journal of catalysis 2003, Vol.213 (1), p.47-62
• Main Authors: Bianchini, Claudio, Dal Santo, Vladimiro, Meli, Andrea, Moneti, Simonetta, Moreno, Marta, Oberhauser, Werner, Psaro, Rinaldo, Sordelli, Laura, Vizza, Francesco
• Format: Article
• Language: English
• Subjects: Catalysis; Catalytic reactions; Chemistry; Exact sciences and technology; General and physical chemistry; Hydrogen bonds; Hydrogenation of sulfur and nitrogen heterocycles; Immobilized catalyst; Mesoporous silica; Ruthenium; Single-site catalyst; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/S0021-9517(02)00027-1

A comparative study of the hydrogenation of various heterocycles, model compounds in raw oil materials, by either Ru(II) complex immobilized on mesoporous silica or Ru(0) nanoparticles deposited on the same support has been performed. The single-site catalyst contains the molecular precursor [Ru(NCMe) 3(sulphos)](OSO 2CF 3) tethered to partially dehydroxylated high-surface-area silica through hydrogen bonds between silanol groups of the support and SO 3 − groups from both the sulphos ligand [ −O 3S(C 6H 4)CH 2C(CH 2PPh 2) 3] and the triflate counter anion. Highly dispersed ruthenium nanoparticles were prepared by calcination/reduction of silica-supported Ru 3(CO) 12. The heterocycles (benzo[ b]thiophene, quinoline, indole, acridine) are hydrogenated to cyclic thioethers or amines. The Ru(II) single-site catalyst is active for both benzo[ b]thiophene and the N-heterocycles, while the Ru(0) catalyst does not hydrogenate the S-heterocycle, yet is efficient for the reduction of the N-heterocycles and simple aromatic hydrocarbons. The surface silanols promote the hydrogenation of indole via NH⋯ O(H)Si hydrogen bonds and can interact with the π-electron density of all substrates.