Continuous Flow Synthesis of Furfuryl Ethers over Pd/C Catalysts via Reductive Etherification of Furfural in Ethanol

Furfural has become one of the most promising building blocks directly derived from biomass. It can be transformed into numerous important biobased chemicals. Among them, furfuryl ethers such as furfuryl ethyl ether (FEE) and tetrahydrofurfuryl ethyl ether (THFEE) are considered to be attractive derivatives, notably as fuel components, due to their high stability and high octane numbers. Therefore, the production of furfuryl ethers from furfural via a hydrogenation route is an important academic and industrial challenge and requires the deployment of new catalytic processes under green and competitive reaction conditions. The existing processes are based on a two-step process combining hydrogenation and reaction with a strong Bronsted acid catalyst in batch conditions. For the first time, a continuous flow one-step process has been elaborated for the conversion of furfural directly into furfuryl ethers based on reductive etherification. The present work explores the catalytic performance in a continuous flow of commercial palladium catalysts supported on activated carbon for the catalytic reductive etherification of furfural with ethanol in the presence of trifluoroacetic acid. The chemical and engineering aspects, such as the mechanisms and reaction conditions, will be discussed.