Decomposition of Fructose in Presence of Hydrochloric Acid in Continuous Subcritical Water System: Formation of 5-Hydroxymethylfurfural, Levulinic, and Formic Acids

Feridoun Salak and Hiroyuki Yoshida. Department of Chemical Engineering, Osaka Prefecture University, Osaka, Japan

This paper deals with the dehydration of fructose (F) to 5-hydroxymethylfurfural (HMF) and the rehydration of HMF to levulinic acid (LA) along with formic acid (FA) in subcritical water (sub-CW) with HCl as catalyst. The experimental conditions were 210 to 270 C, 4 to 15 MPa, and residence time of 0.5 to 300 s. The pressure did not affect the decomposition reactions. This differed from other operating variables. The main products were found to be HMF, 2-furaldehyde (2FA), LA, FA, and soluble polymers. The HMF, LA, and FA were also individually subjected for decomposition at the same condition. During the decomposition of F soluble polymers were main by-products. The same by-product was also identified from the decomposition of HMF. However, we distinguished between these two polymers in a proposed reaction model. Kinetics of the decomposition and formation reactions was developed including the kinetics for the soluble polymers. Theoretical time course of their yields calculated using the kinetic constants obtained from the proposed reaction pathway showed good agreement with experimental results.