Continuous-flow reductive etherification of furfural over CuAlOx catalyst combined with HZSM-5-Al2O3 composite

Furfuryl alkyl ethers (FAEs) are considered attractive biofuels or gasoline additives. Reductive etherification of bio-based furfural (FF) is a promising method for production of these compounds. In present work, we study the catalytic behavior of Cu-Al mixed oxide in combination with HZSM-5-Al2O3 composites for the syntheses of FAEs in a flow reactor using H2 as a reducing agent. The Cu-based catalyst ensures the hydrogenation of FF to furfuryl alcohol, which then reacted with alcohol in the presence of the acid catalyst. It was found that the reaction of FF with 2-propanol over catalytic system including HZSM-5(Si/Al = 40)-Al2O3 leads to the formation of 2-(isopropoxymethyl)furan (IMF) in excellent yield due to the optimal concentration of strong Bronsted acid sites in the composite. Lower selectivity to IMF was observed in the presence of HZSM-5 with Si/Al ratio of 15, 25 and 140. In addition, the use of primary alcohols instead of 2-PrOH gives a significantly lower yield of FAEs.