Direct Liquefaction of Bark of Japanese Red Pine by Steam Explosion

Abstract

Steam explosion was applied to liquefaction of bark (Japanese red pine) to increase the oil yield. When the bark was liquefied using an autoclave, the oil yield was as low as 23% because condensation or repolymerization of reactive fragments was promoted due to the slow cooling. However, the oil yield in liquefaction by steam explosion (300°C, 10MPa) reached 33%. This can be caused by the rapid cooling in steam explosion, which retards condensation or repolymerization leading to the formation of char. The heating value (30 MJ/kg) of oil was almost the same as that obtained by the autoclave experiment.
The oil yield in steam explosion depended on catalyst loading, reaction temperature and holding time. It was decreased by addition of catalyst ; that is, no catalyst is needed for steam explosion. With respect to reaction temperature, the yield increased with the rise in temperature from 200 to 300°C. Liquefaction was completed within 5-10 minutes, and prolonged holding time tended to decrease the oil yield.