Abstract
5-Hydroxymethylfurfural (5-HMF) is one of the intermediates in char polymerization, a side reaction that takes place in the supercritical water gasification (SCWG) of biomass. In this paper we report a kinetic investigation of the polymerization of 5-HMF in the process of solid char formation in an acidic environment. This is due to the fact that 5-HMF is copresent with other product acids during biomass decomposition. Mixtures of 5-HMF and hydrochloric acid were therefore treated in a subcritical condition (350°C; 25 MPa) in the present work. The concentration of 5-HMF ranged from 0.01 to 0.05 M, while that of HCl was 0.01 M (at room temperature). The rates of gas and char production from 5-HMF obtained from experiments with and without acid (Chuntanapum and Matsumura, 2009) were compared. Acid catalyzed both the gasification and polymerization pathways of 5-HMF, especially the decomposition reaction of 5-HMF to TOC, the rate constant of which was increased by two orders of magnitude.
