Two-Step Hydrolysis of Japanese Cedar as Treated by Semi-Flow Hot-Compressed Water with Acetic Acid

Abstract

Japanese cedar (Cryptomeria japonica) as one of the softwoods was treated by two-step semi-flow hot-compressed water with 3.0 wt% acetic acid at 210 and 260°C/10 MPa/15 min, for the first and second stages, respectively. Totally, 85.0% of Japanese cedar could be solubilized into the hot-compressed water, while the rest of 15.0% remained as residue composed mainly of 11.7% lignin with 3.3% cellulose being incompletely hydrolyzed. In comparison with the two-step treatment of Japanese cedar without acetic acid addition reported previously, it was revealed that this current two-step treatment with acetic acid could be performed at lower temperatures with comparable yields of hydrolyzed products from hemicellulose and cellulose as well as lignin-derived products. The addition of acetic acid has shown a possibility to improve the hydrolysis and decomposition of wood cell wall components. However, due to decomposition reaction caused by acetic acid applied, the most appropriate optimum treatment conditions should be studied further.