Au/mesoporous-TiO2 as catalyst for the oxidation of alcohols to carboxylic acids with molecular oxygen in water

Abstract

Mesoporous TiO2 (meso-TiO2) with sharp pore size distribution was synthesized by hydrothermal method. The obtained meso-TiO2 is in pure anatase phase and presents spheric aggregates with diameter of 1.0–1.5μm, which consists of nanoparticles with size of 6–10nm. Au supported on meso-TiO2 (Au/meso-TiO2) was prepared by urea deposition–precipitation method using HAuCl4 as gold source. The catalyst was characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The catalytic performance of Au/meso-TiO2 was studied in the oxidation of 1-pentanol to n-valeric acid with molecular oxygen as oxidant in water under basic conditions. It was found that meso-TiO2 is a better support for gold catalyst in the oxidation of 1-pentanol than NaY zeolite, hydrotalcite, and nano-TiO2. Deposition–precipitation time, calcination temperature and Au loading affected the catalytic performance of Au/meso-TiO2. The catalyst can also effectively catalyze the oxidation of aliphatic (C3–C10) and aromatic alcohols to the corresponding carboxylic acids.