Selective Oxidation of n‐Butanol Using Gold‐Palladium Supported Nanoparticles Under Base‐Free Conditions

Abstract

The base-free selective catalytic oxidation of n-butanol by O2 in an aqueous phase has been studied using Au-Pd bimetallic nanoparticles supported on titania. Au-Pd/TiO2 catalysts were prepared by different methods: wet impregnation, physical mixing, deposition-precipitation and sol immobilisation. The sol immobilisation technique, which used polyvinyl alcohol (PVA) as the stabilizing agent, gave the catalyst with the smallest average particle size and the highest stable activity and selectivity towards butyric acid. Increasing the amount of PVA resulted in a decrease in the size of the nanoparticles. However, it also reduced activity by limiting the accessibility of reactants to the active sites. Heating the catalyst to reflux with water at 90 °C for 1 h was the best method to enhance the surface exposure of the nanoparticles without affecting their size, as determined by TEM, X-ray photoelectron spectroscopy and CO chemisorption analysis. This catalyst was not only active and selective towards butyric acid but was also stable under the operating conditions.

Au‐Pd Bimetallic Nanoparticles Immobilised on Titanate Nanotubes: A Highly Active Catalyst for Selective Oxidation

“…The catalyst sample prepared by sol‐immobilisation (Figure a) exhibited the narrowest particle size distribution and smallest mean particle size. The catalyst prepared at reflux (Figure b) exhibited a slightly larger mean particle size, which is in agreement with previous studies concerning the effect of reflux . Catalysts prepared by adsorption (Figure c) exhibited a small mean particle size, and a slightly wider PSD.…”

Towards Mechanistic Understanding of Liquid‐Phase Cinnamyl Alcohol Oxidation with tert‐Butyl Hydroperoxide over Noble‐Metal‐Free LaCo1–xFexO3 Perovskites

“…For liquid-phase alcohol oxidation reactions, it is known that basic properties, either by adding a base or using an intrinsically basic catalyst, are beneficial for the oxidation reaction. [13] The basicity of the perovskite catalysts was investigated by the Knoevenagel condensation between malononitrile and benzaldehyde in MeCN yielding benzylidenemalononitrile. Since the Knoevenagel condensation is a base-catalyzed reaction, it can be used to determine the relative basicity of different catalysts, [56] which has been reported earlier as a suitable method to determine the basic properties of zeolite materials in the liquid phase.…”

Highly Active Gold and Gold–Palladium Catalysts Prepared by Colloidal Methods in the Absence of Polymer Stabilizers

“…Supported gold and gold–palladium nanoparticles are exceptionally effective catalysts for selective oxidation . The structural properties of these catalysts (i.e., particle size, composition, and oxidation state) have a significant influence on catalytic activity, selectivity, and stability .…”