1. Key Laboratory of Renewable Energy and Gas Hydrate of Chinese Academy of Sciences, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China;
2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China

Hemicellulose can produce more acid content than cellulose and lignin via pyrolysis. This work reduced the hemicellulose and water content of pine via low temperature pretreatment to improve the bio-oil quality. The chemical composition and FT-IR analysis of pine after pretreatment show that the lignin content increases and the carbonization of pine takes place, which results in the decrease of bio-oil yield and the increase in yield of char and no-condensed gas. With increasing pretreatment temperature, the important characteristics of the bio-oil, such as water content, high heating value, kinematic viscosity, and density all increase, and solid particles content decreases, while pH value decreases after an initial increase. The ¹³C nuclear magnetic resonance (NMR) show that the aliphatic carbon of bio-oil decreases, while the aromatic and the aromaticity increases.