Characteristics of liquid products fromhydrothermal liquefaction of typical cropstraws under CO atmosphere

Abstract

The hydrothermal liquefaction of three typical crop straws (corn, wheat and cotton straws) under CO atmosphere was carried out in a 500 mL autoclave. Simultaneously, the main properties and chemical compositions of the liquid products (LPs) were investigated by the elemental analysis, gas chromatography–mass spectrometry and 1 H nuclear magnetic resonance. In the hydrothermal liquefaction under CO atmosphere, the conversion of typical crop straws and the yield of LPs are respectively up to 82?4–91?6% and 35?8–39?5%, and the LPs with low O content (10?64–14?01%), high H/C ratio (1?05–1?28) and trace amounts of S and N have a high heating value between 34?14 and 36?73 kJ g 21 . The results of gas chromatography–mass spectrometry and 1 H nuclear magnetic resonance analyses show that the LPs are mainly composed of phenol derivatives, long chain alkanes and other O containing compounds (carboxylic acids, ketones and esters) and also contain a large amount of aliphatic fractions, suggesting that the LPs might be potentially valuable resources as renewable fuel and chemical feedstocks. In addition, it has been found that the cleavage of C–O bond in alkoxyl groups is easy in the hydrothermal liquefaction process, while the removal of O from phenolic hydroxyl group is difficult.