Catalytic Degradation of Poplar by Fe and Fe/Na 2 CO 3 Under Different Hydrothermal Liquefaction Processes

The production of bio-oil from poplar sawdust Under direct/stepwise hydrothermal liquefaction (HTL) with Na2CO3 or Na2CO3/Fe as catalyst was investigated. The results showed that as the increase of liquefaction temperature in the stepwise HTL, the carbon content in heavy oil (HO) gradually increased, while the oxygen in light oil (LO) kept decreasing. The highest total bio-oil yield of 57.09% was obtained from the stepwise Na2CO3/Fe-catalyzed HTL with a residence time of 20 min. Via GC-MS analysis, it was found that the Na2CO3 catalyzed stepwise HTL dramatically improved the yield of dibutyl phthalate. While the Na2CO3/Fe catalyzed HTL helped promote the production of phthalic acid, butyl 2-ethylhexyl ester and phthalic acid, diisobutyl ester.