PREPARATION OF BIODIESEL FROM SOYBEAN OIL WITH HIGH ACID VALUE BY TWO-STEP CATALYZED PROCESS

Two-step catalyzed process was adopted to prepare biodiesel from Soybean oil with high acid value.Free fatty acid of Soybean oil with high acid value was esterified with methanol catalyzed by cationic exchange resin 002CR which filled in a packed reactor in the first step,and then triglyceride(TG) of soybean oil was transesterified with methanol catalyzed by potassium hydroxide.Results showed that the optimal esterification conditions were:the ratio of methanol to fatty acid was 2∶1,reaction temperature was 60 ℃,dosage of reactant was 3 mL/min.Under this condition,the acid value of soybean oil was under 1 mgKOH/g.Transesterification was performed at 1.5 % of potassium hydroxide,65℃ of reaction temperature,60 min of reaction time,and 6∶1 of mole ratio of methanol to TG,and the quality of the product reached the standard of GB252-1994.