Hydrothermal liquefaction of crop straws: Effect of feedstock composition

Abstract

Hydrothermal liquefaction of four crop straws, including corn straw (CS), peanut straw (PS), soybean straw (SS), and rice straw (RS), were examined at 320 °C for 60 min to explore the effect of feedstock composition on the products distribution and properties of the bio-oil. SS produced the highest bio-oil yield of 15.8 ± 0.8 wt%, followed by RS (15.1 ± 0.7 wt%), PS (14.6 ± 0.7 wt%), and CS (7.9 ± 0.7 wt%). The significant difference in bio-oil yield was ascribed to the cellulose content and the mass ratio of cellulose to hemicellulose (wcellulose/whemicellulose) of the feedstock. Elemental analysis showed that the four bio-oils had similar elemental compositions of C, H and O. Ketones and phenolic compounds occupied a large proportion of the four bio-oils, and their relative contents were related to the cellulose content and wcellulose/whemicellulose value of the feedstock. Feedstock with high cellulose content and wcellulose/whemicellulose value would lead to bio-oil with high amount of ketones.