Applied Catalysis A: General, Vol.475, 203-210, 2014
Amine-stabilized small gold nanoparticles supported on A1SBA-15 as effective catalysts for aerobic glucose oxidation
The preparation of gold nanoparticles (AuNPs) supported on the alumina- and amine-modified silica SBA-15 and systematic studies of their structural properties and behaviour in glucose oxidation are presented. The AuNPs were deposited using either direct reduction or colloidal deposition method. Catalysts were characterized by nitrogen adsorption, XRD, XPS, STEM, HRTEM,Al-27 MAS NMR,H-1 NMR, DLS, HPLC, ICP MS and thermogravimetry to determine structure/activity relationship in the aerobic glucose oxidation. The highest catalytic activity ca. 800 mmol(GA)/g(Au) min was achieved for AuNPs prepared by a direct reduction method using SBA-15 first modified with alumina (1 wt.%) and then with aminopropyl groups serving as strong adsorption sites. It was notably larger than shown by commercial Au/Al2O3 and Au/TiO2 catalysts (380 and 340 mmol(GA)/g(Au) min, respectively). Owing to excellent and stable dispersion of AuNPs and their small sizes < 6 nm, the catalysts showed very good stability, demonstrated in 7 reaction cycles. The impact of specific functionalities on the size, dispersion and stability of AuNPs was discussed and high selectivity towards gluconic acid formation was demonstrated. (C) 2014 Elsevier B.V. All rights reserved.
Keywords:Gold nanoparticles;Aerobic glucose oxidation;Mesostructured materials;Amine and alumina functionalization