Origin of carbon in the bio-oil from hydrothermal liquefaction of protein and glucose via isotopic labeling

Abstract

Protein and carbohydrate in biomass (algae, sewage sludge, etc.) have synergistic effect on bio-oil yield during HTL, but the mechanism is still unclear. In this study, isotopic labeling was used to explore the origin of carbon in the bio-oil obtained from HTL of protein and glucose. The results showed that the interaction between protein and glucose has evident synergistic effect on the nitrogen content and antagonistic effect on the oxygen content in the bio-oil. Meanwhile, no carbon in the glucose was involved in the formation of Indole, p-cresol, 9-octadecenamide, (Z)- and octadecanamide during HTL of protein and glucose. Pyrrolidine,1-acetyl- can be considered as a compound formed through the interaction of protein and glucose. In addition, 13C in the labeled glucose participated in the formation of acid, aldehyde, aliphatic and aromatic compounds, but these compounds probably had a high boiling point (>300 °C). The results in this study could provide insight into the interaction mechanism between protein and glucose for further studies.