Sulfonated graphene oxide/MnFe₂O₄ magnetic nanocomposite for effective 5-hydroxymethylfurfural etherification in...

Herein, a solid acid catalyst, SO₃H-GO/MnFe₂O₄, was synthesized through a three-step process, including the preparation of graphene oxide (GO), deposition of MnFe₂O₄ nanoparticles onto GO, and subsequent sulfonation with chlorosulfonic acid. The synthesized catalyst was completely analyzed by numerous techniques, including FT-IR, TEM, XRD, EDX, VSM, and acid-base titration, approving the successful incorporation of MnFe₂O₄ nanoparticles and -SO₃H groups onto GO. The activity of prepared SO₃H-GO/MnFe₂O₄ was determined in the etherification of 5-hydroxymethylfurfural (HMF) to 5-ethoxymethylfurfural (EMF). The reaction factors were optimized and the optimum condition was obtained at 120 °C, 30 mg of catalyst dosage, and time of 6 h, providing high EMF yield (93.2%), and selectivity (96%). The prepared particles were easily isolated from the mixture by a magnet and showed excellent recyclability, retaining most of its activity over four consecutive cycles. Moreover, the catalyst was also efficient in the direct conversion of biomass-derived sugars (fructose, glucose, and sucrose) to EMF.