Catalytic hydrogenation and etherification of 5-Hydroxymethylfurfural into 2-(alkoxymethyl)-5-methylfuran and 2,5-bis(alkoxymethyl)furan as potential biofuel additives

Authors: ELSAYED, ISLAM - Mississippi State University; Jackson, Michael - Mike; HASSAN, EL BARBARY - Mississippi State University

Submitted to: Fuel Processing Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2020
Publication Date: 11/24/2020
Citation: Elsayed, I., Jackson, M.A., Hassan, E. 2020. Catalytic hydrogenation and etherification of 5-Hydroxymethylfurfural into 2-(alkoxymethyl)-5-methylfuran and 2,5-bis(alkoxymethyl)furan as potential biofuel additives. Fuel Processing Technology. 213. Article 106672. https://doi.org/10.1016/j.fuproc.2020.106672.
DOI: https://doi.org/10.1016/j.fuproc.2020.106672

Interpretive Summary: In this research we demonstrate a new route to biofuel additives that are made from HMF and common alcohols. HMF is a compound that can be made from the sugars obtained from crop residues or forestry wastes and is the central compound in many schemes for the biobased economy and biorefineries. Our results show that a two-step process yields the fuel additives in high yield. The novelty of our approach is that the first step is performed with an inexpensive catalyst that is also magnetic. This means that the catalyst can be removed with a magnet before the second catalyst is added. This simplification of the process should make this utilization of crop residue and forestry waste more attractive to biorefineries adding demand to an otherwise wasted resource.

Technical Abstract: In this study, 5-hydroxymethylfurfural (HMF) was converted into several biodiesel compounds such as 5-(alkoxymethyl)furfurals (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs) through two-step sequential hydrogenation and etherification reactions. In the first step, zinc-iron magnetic nanocatalyst supported on activated carbon (ZnO-Fe3O4/AC) was prepared for the selective hydrogenation of HMF into furfuryl alcohols via Meerwein-Ponndorf-Verley (MPV) reaction in three different hydrogen donor alcohols (ethanol, 1-propanol, and 1-butanol). The important physical properties of the catalyst such as crystallinity, chemical composition, morphology, reduction behavior, and surface area were studied by using several analytical techniques. The effect of hydrogenation parameters such as catalyst concentration, temperature, and time on the selectivity of furfuryl alcohols and HMF conversion were studied. The best hydrogenation results were obtained with 0.2 mmole HMF and 100 mg of catalyst at 200 °C for 12h. In the second step, three commercial Brønsted acid catalysts including Amberlyst 16, Amberlyte IR120, and Dowex 50WX2 were used to convert the hydrogenated products into 5-(alkoxymethyl)furfurals (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs). At the optimum etherification conditions (65°C and 10h), a spectrum of mono-, di-, and tri- ether compounds were obtained. At the end of the two steps, 90% of ethoxymethyl, 86.6% of propoxymethyl, and 84% of butoxymethyl ether compounds were obtained with Amberlyst 16, Amberlyte IR120, and Dowex 50WX2 catalysts, respectively. Kinetic study was performed at three different temperatures (453.15, 463.15, and 473.15 K) to determine rate constants and activation energies of the hydrogenation products.