Preparation of Supported Gold Nanoparticles by a Modified Incipient Wetness Impregnation Method

Abstract

In this work, we show that if the mere procedure of impregnation of oxide supports with chloroauric acid, which is well-known to lead to large gold particles, is followed by a step of washing with ammonia, small gold particles (3-4 nm) can be obtained after a treatment of calcination at 300 degrees C on any type of oxide supports (alumina, titania, silica). Moreover, gold leaching is very limited during the washing step, and a large range of gold loadings (0.7-3.5 wt %) can be achieved. Elemental analysis, Raman spectroscopy, and temperature programmed desorption under argon show that this ammonia posttreatment results in the removal of chloride ligands from the coordination sphere of Au(III) precursor and their replacement by ammine ligands, leading to an ammino-hydroxo or an ammino-hydroxo-aquo gold complex and not to gold hydroxide. The Au/TiO(2) catalysts prepared with this modified procedure of impregnation are almost as active as those prepared by deposition-precipitation with urea in the CO oxidation reaction performed at room temperature.

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

“…To circumvent this problem, Delannoy et al [177] proposed a modified IWI method for the synthesis of gold catalysts supported on different oxides, including silica, involving a washing step with ammonia 1 M or with ammonium chloride 0.25 M, followed by calcination at high temperature (300 °C). The ammonia washing removes the chloride ligands responsible for the aggregation of AuNPs, and leads to the formation of an amino-hydroxo-aquo cationic gold complex…”

Formation of nanometer-sized Au particles on USY zeolites under hydrogen atmosphere

“…Cation exchange using [Au(en) 2 ] 3+ and incipient wetness impregnation have been employed for the loading of zeolites [20,21].…”

Optimized Design of Pt‐Doped Bi2WO6 Nanoparticle Synthesis for Enhanced Photocatalytic Properties

“…Impregnation followed by solid-state reduction at 200°C is the most commonly used method for the preparation of metal catalysts. [12] In a typical experiment, 6 has a band gap of 2.8 eV that can be excited by a UV source. [13] The electrons promoted to the Bi 2 WO 6 conduction band can then reduce the metal salt adsorbed on the surface of the semiconductor.…”