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.

Study of 1D Titanate‐Based Materials –New Modification of the Synthesis Procedure and Surface Properties‐Recent Applications

“…Titania may be used as a semiconductor that is biocompatible, cheap, eco‐friendly, with an important band gap energy, stable phases, etc. . Furthermore, nano‐structured titania possesses some physico‐chemical characteristics, such as the crystal structure, melting temperature, solubility, band gap energy, acid‐base character, surface area, electric charges and others, that are different from those encountered in the conventional form .…”

‘Oxygen-Consuming Complexes’–Catalytic Effects of Iron–Salen Complexes with Dioxygen

“…The main product of an auto-oxidative reaction was usually ketone, but alcohol and epoxide were also observed [61,62]. The same products were formed during cyclohexene oxidation in the presence of molecular dioxygen and a bimetallic gold-iron nanocatalyst supported on commercial titania [63]. The lower stability constant of [(salen)Fe II ], amounting to 3•10 17 M −1 [25], compared with the one characteristic of very stable [(salen)Fe III ] + [71], equal to 7.1•10 25 M −1 , favors electron transfer reactions between electron acceptors such as dioxygen and [(salen)Fe II ], resulting in [(salen)Fe III --O 2 ] complexes [25].…”

Preparation of Nanocatalysts Using Deposition Precipitation with Urea: Mechanism, Advantages and Results

“…The AuNPs and IrNPs in this catalyst were in the same region but did not form an alloy or bimetallic particles. Finally, other bimetallic systems were also prepared by CO-DPU, such as Au-Fe/TiO 2 [23], Au-Cu/TiO 2 [69], Ag-Ce/mesoporous-TiO 2 [83], Fe-Ni/SiO 2 [10], and Cu-Ni/Al 2 O 3 [49].…”

“…The influence of these parameters on the nature of the deposit obtained is discussed in the following. However, the DPU was used to prepare materials based on different metals, e. g., gold nanoparticles (AuNPs) [1,2,4,6,[13][14][15][16][17][18][19][20][21], silver nanoparticles (AgNPs) [6,7,22], platinum nanoparticles (PtNPs) [6], iron nanoparticles (FeNPs) [23], copper nanoparticles (CuNPs) [3,12,18,[24][25][26][27][28][29][30], nickel nanoparticles (NiNPs) [5,[31][32][33][34][35][36][37], cobalt nanoparticles (CoNPs) [38][39][40][41], ruthenium nanoparticles (RuNPs) [13,42], and others. The supports used have different natures: simple oxides (TiO 2 [3,4,7,13,14,…”