Supanan Ampawa
Mahidol University, Thailand
Title: Effects of triazolebased ligand structures on catalyst loadings and activities of Pd nanoparticle for selective aerobic alcohol oxidation
Biography
Biography: Supanan Ampawa
Abstract
A series of triazole-based ligands containing a hydroxyl group, tris(triazolyl) methanol (Htbtm), bis(triazolyl) phenyl methanol (Hbtm), and phenyl(pyridin-2-yl)(triazolyl) methanol (Hpytm), were synthesized and functionalized on 3-chloropropyl silica via deprotonation followed by nucleophilic addition. Subsequent addition of Pd(OAc)2 (OAc = CH3COO‒) onto these supports was carried out. It was found that ligand structures significantly affected Pd loading, which followed the trend: SiO2-tbtm > SiO2-btm ~ SiO2-pytm. Moreover, the influence of different ligand structures on Pd stabilization and catalytic efficiency toward Pd nanoparticle (NP)-catalysed aerobic alcohol oxidation to the corresponding aldehydes was studied. Based on XPS analysis, Pd(II) species were reduced in situ in the presence of alcohols during the first catalytic reactions to generate the active Pd NPs catalysts. Immobilization of Pd NPs on tbtm, btm, pytmmodified silica supports were confirmed by HR-TEM showing average particle diameters of 6.4, 4.8 and 8.5nm, respectively. At 60°C, the Pd NPs stabilized by SiO2-btm exhibited the highest turnover numbers for aerobic oxidation of benzyl alcohol in an ethanol solvent.