Liquefaction of rice stalk in sub- and supercritical ethanol

Rice stalk (RS) was liquefied in ethanol under sub- and supercritical conditions in a batch autoclave; the influences of reaction temperature, RS/ethanol ratio and residence time on the liquefaction behavior were investigated. Under the optimized conditions, i. e. 325 °C, a RS/ethanol ratio of 1/10 (g/mL), and a residence time of 60 min, the RS conversion and oil yield reach 78.32% and 55.03%, respectively. The GC/MS analysis results illustrate that the dominant components of the bio-oil are phenols and esters, which account for about 50% of the bio-oil product. The bio-oil product obtained exhibits a high heat value (HHV) of 28.95 MJ/kg, a kinematic viscosity of 5.63 mm2/s, and a water content of 2.2%.