Tổng hợp biodiesel từ bùn thải trong điều kiện methanol-nước cận tới hạn

Abstract

In the presence of water, biodiesel can be produced from the reaction of methanol with feedstock oil under subcritical condition without the need of conventional catalysts such as potassium hydroxide and sulfuric acid. In this study, in-situ transesterification under subcritical condition of methanol and water was studied and compared with conventional catalyzed transesterification method. Sludge was used as raw material. Experimental results showed that fairly high biodiesel conversion rate (90.46%) could be achieved in a reasonable reaction time of 6 hours at 200°C under subcritical condition. The conversion rate reached 97.05% when sulfuric acid was used as catalyst under the reaction condition of 55°C in 24 hours. Since no catalyst was employed in the subcritical condition, the process was simpler and more environmental friendly than traditional methods. In addition, the removal of water was unnecessary since it had been employed as acatalyst under subcritical condition. Therefore, in-situ transesterification under subcritical condition is potentionally applied with low grade feedstocks with high FFA and moisture content.