Magnetic material grafted cross-linked imidazolium based polyionic liquids: an efficient acid catalyst for the synthesis of promising liquid fuel 5-ethoxymethylfurfural from carbohydrates

Magnetic material grafted with acid polyionic liquids was successfully prepared by the radical oligomerization of bis-vinylimidazolium salts on the surface of mercaptopropyl-modified silica-coated Fe3O4, and well characterized by several model technologies. The as-prepared magnetic catalyst (Fe3O4@SiO2–SH–Im–HSO4) showed high catalytic activity for the synthesis of 5-ethoxymethylfurfural (EMF) from 5-hydroxymethylfurfural (HMF) and fructose-based carbohydrates. The reaction temperature showed a remarkable effect on EMF yield. High EMF yield of 89.6% was obtained at 100 °C by the etherification of HMF. The one-pot conversion of fructose, sucrose and inulin catalyzed by Fe3O4@SiO2–SH–Im–HSO4 generated EMF with yields of 60.4%, 34.4% and 56.1%, respectively. The catalyst could be readily separated from the reaction mixture by a permanent magnet, and showed high stability in recycling experiments. This study shows a green and sustainable method for the synthesis of value-added liquid fuel from renewable resources.