Flow enzymatic esterification of 5-hydroxymethylfurfural and liquid-liquid extraction of 5-acetyl-hydroxymethylfurfural using deep eutectic solvents in semicontinuous mode

This study explored for the first time the use of a flow-packed bed bioreactor for producing 5-acetyl-hydroxymethylfurfural (5-acetyl-HMF) and semicontinuous liquid-liquid extraction with a deep eutectic solvent (DES): choline chloride: glycerol= 1:2 (ChCl: GLY=1:2). The flow reaction system provided a specific productivity that was considerably higher than that observed in the batch reactor (1 g(Product)/min center dot g(Biocat) vs. 0.07 gProduct/min center dot g(Biocat)). The biocatalyst Novozym 435 (R) showed high operational stabilities in continuous mode and sequential batch mode without losses of activity. In continuous mode, an 80 % conversion was achieved with 100 mM 5-hydroxymethylfurfural (HMF) and a flow rate of 0.05 mL/min. The separation in the semicontinuous mode was more efficient than that for the extraction batch system (70 % vs. 38 %). Finally, in the future, a combination of continuous enzymatic transesterification and semicontinuous separation of 5-acetyl-HMF will provide an efficient, sustainable biocatalytic process that can be industrially scaled.

Automated summary

This study investigated the use of a flow-packed bed bioreactor for producing 5-acetyl-hydroxymethylfurfural (5-acetyl-HMF) and semicontinuous liquid-liquid extraction with a deep eutectic solvent (DES). The flow reaction system showed higher specific productivity compared to the batch reactor. The biocatalyst Novozym 435 (R) demonstrated high operational stabilities in continuous and sequential batch modes without any loss of activity.