Bioresource Technology, Vol.243, 1069-1077, 2017
Sugars and char formation on subcritical water hydrolysis of sugarcane straw
Subcritical water has potential as an environmentally friendly solvent for applications including hydrolysis, liquefaction, extraction, and carbonization. Here, we report hydrolysis of sugarcane straw, an abundant byproduct of sugar production, in a semi-continuous reactor at reaction temperatures ranging from 190 to 260 degrees C and at operating pressures of 9 and 16 MPa. The target hydrolysis products were total reducing sugars. The main products of sugarcane straw hydrolysis were glucose, xylose, arabinose, and galactose in addition to 5-hydroxymethylfurfural and furfural as minor byproducts. Fourier transform infrared spectroscopy and thermogravimetric analysis provided additional information on the surface and bulk composition of the residual biomass. Char was present on samples treated at temperatures equal to and greater than 190 degrees C. Samples treated at 260 degrees C contained approximately 20 wt% char, yet retained substantial hemicellulose and cellulose content. Hydrolysis temperature of 200 degrees C provided the greatest TRS yield while minimizing char formation. (C) 2017 Elsevier Ltd. All rights reserved.