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

Abstract

In this study, 5-hydroxymethylfurfural (HMF) was converted into several biofuel additives such as alkoxymethylfurans (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 BHMF and 5-MFA 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 (BHMF and 5-MFA), 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 12 h. In the second step, three commercial Brønsted acid catalysts were used to convert the hydrogenated products into alkoxymethylfurans (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs). At the optimum etherification conditions (65 °C and 10 h), a spectrum of mono-, di-, and tri- ether compounds were obtained. The hydrogenation catalyst (ZnO-Fe3O4/AC) was recycled and used for five times without a remarkable reduction in its catalytic activity.