Activity of bimetallic gold-iron catalysts in adipic acid production by direct oxidation of cyclohexene with molecular oxygen

Abstract

This paper explores the properties of bimetallic catalysts based on gold and iron nanoparticles “Au-Fe/TiO2” and their application in the adipic acid production by direct oxidation of cyclohexene with molecular oxygen. The bimetallic materials were prepared with different amounts of gold and iron in two different methods: simultaneous deposition of Au and Fe using co-deposition precipitation with urea (Co-DPU), and deposition precipitation of gold followed by iron impregnation (DPU+IMP). The obtained catalysts were characterized by several techniques, such as XRD, RD/UV-Vis, ATR, ICP and BET. The properties of the catalysts prepared by different methods were compared, revealing that the metallic nanoparticles in the two methods differ in oxidation state, shape and size decrement. For cyclohexene oxidation by molecular oxygen, an important conversion of cyclohexene (≈50 %) was obtained just after 2h in the case of AuFeC was observed. In terms of selectivity, all catalysts showed an excellent adipic acid production up to 90 %. The research establishes a green chemistry route from direct oxidation of cyclohexene to adipic acid using bimetallic catalyst in one-step reaction.