An unconventional iron oxide catalyst for 5-hydroxymethylfurfural oxidation to 2,5-diformylfuran

• Published in: Organic & biomolecular chemistry 2023-05, Vol.21 (18), p.3829-3836
• Main Authors: Kumar, Ajay, Chauhan, Arvind Singh, Bains, Rohit, Das, Pralay
• Format: Article
• Language: English
• Subjects: Catalysts; Catalytic activity; Catalytic converters; Conversion; Ferric oxide; Heavy metals; Hydroxymethylfurfural; Inspection; Iron oxides; Oxidation; Phase transitions; Reagents; Recyclability; Transition metals; X ray photoelectron spectroscopy; Xylene
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/d3ob00314k

Commonly used magnetic iron oxide (γ-Fe 2 O 3 ) was examined for the first time as an unconventional catalyst for 5-hydroxymethylfurfural (5-HMF) oxidation to 2,5-diformylfuran (DFF). Fascinatingly, the magnetic support showed remarkable catalytic activity for this conversion, especially in nanoscale size (≤50 nm). The developed mild reagent system consisting of γ-Fe 2 O 3 and molecular O 2 in xylene solvent delivered DFF with 94% selectivity and 82% conversion at 135 °C for 12 h. A deep inspection of the mechanistic study through IR and XPS analysis revealed a phase transition (γ-Fe 2 O 3 to Fe 3 O 4 ) during the reaction, and then its reversal to the parent form after catalyst activation. The loss in crystallinity and increase in the particle size of the catalyst after the reaction were explicitly analysed by XRD and TEM studies, respectively. The excellent activity of the catalyst was even noticed by a recyclability test for six cycles. The method avoided the requirement of high-pressure equipment, costly noble and transition metals, and harsh basic environments. Commonly used magnetic iron oxide (γ-Fe 2 O 3 ) was examined for the first time as an unconventional and recyclable catalyst for 5-hydroxymethylfurfural oxidation to 2,5-diformylfuran by avoiding the additional need for bases, additives and high-pressure equipment.