화학공학소재연구정보센터
Energy & Fuels, Vol.27, No.8, 4729-4738, 2013
Upgrading of Crude Duckweed Bio-Oil in Subcritical Water
In the present work, crude bio-oil derived from the hydrothermal liquefaction (HTL) of duckweed (Lemna sp.) was treated in subcritical water at different reaction environment (H-2,CO), temperature (330-370 degrees C), time (2,4 h), and Pt/C sulfide (Pt/C-S) catalyst loading (0-20 wt %), aiming to find how these parameters affect the products yield and properties of the treated oil. The results demonstrated that treating the crude duckweed bio-oil in subcritical water with or without catalyst under either H-2 or CO environment effected several desirable changes in the oil. Compared to H-2, using CO as initial gas led to treated oil with higher yield, lower viscosity, and higher hydrogen, and could also achieve larger energy recovery. Higher temperatures and longer reaction times produced treated oil with better quality but at the expense of reducing oil yield, respectively, due to the increased coke and gas formation. Larger catalyst loading was also favorable in realizing high quality treated oil, but it also promoted the production of coke and water-soluble material. During the treatment, the oxygenates in the crude duckweed bio-oil were more reactive than that of the nitrogenates, especially with catalyst. The higher heating values of the treated oils were estimated within the range 34.3-38.2 MJ/kg. CO2 was the dominant gas formed under either CO or H-2 environment. Thus, this study suggested that the crude bio-oil from the HTL of duckweed can be effectively upgraded in subcritical water.