Subcritical water hydrolysis of soybean husk catalyzed by WO3/ZrO2 for enhanced conversion of fermentable sugar to platform chemicals

Soybean husk is a lignocellulosic residue with potential to be utilized as feedstock for platform chemicals' production such as 5-hydroxymethylfurfural, furfural, formic acid, acetic acid, and levulinic acid. In this study, the conversion of soybean husk into fermentable sugars and platform chemicals through subcritical water hydrolysis catalyzed by tungstated zirconia (WO3/ZrO2) was investigated. The effect of temperature (240 degrees C and 280 degrees C) and mass of tungsten (W) in WO3/ZrO2 (5, 10, and 20%) in relation to fermentable sugars' yield (Y-FS) and platform chemicals' yield (Y-PC) was assessed. The results showed an increase in Y-PC (12.91 +/- 1.08 g/100g) and a decrease in Y-FS in the presence of WO3/ZrO2, especially with 20% W, indicating the increase and simultaneous conversion of fermentable sugars into platform chemicals when using WO3/ZrO2 with the highest percentage of W. The temperature showed influence on yield of different types of platform chemicals. Formic acid and levulinic acid were obtained in the highest concentrations at 240 degrees C whereas the highest conversion to acetic acid, 5-hydroxymethylfurfural, and furfural was at 280 degrees C, with WO3/ZrO2 20% W.