Improving cold flow properties of biodiesel produced from palm fatty acid distillate

Palm fatty acid distillate (PFAD) with free fatty acid (FFA) of 87.1±1.3% was used as raw material for biodiesel production through acid-catalyzed esterification and alkali purification process. To achieve ASTMD6751-02 standard in cold flow properties, the isopropyl ester should be produced as follows. The 1st esterification at 70˚C for 5 hour of PFAD with isopropanol at 1:6 molar ratios and 10wt% of conc. H2SO4, the product with cloud point and pour point of 14.0±0.0 and 6.0±0.0oC, respectively, was obtained. The 2nd esterification at 60˚C for 2 hour of remaining FFA (9.1±0.01 wt%) with methanol at 1:8 molar ratios and 3wt% of conc. H2SO4, the biodiesel with FFA contents, cloud point and pour point of 2.1±0.2 wt%, 18.5±0.7˚C and 0.8±0.4˚C, respectively, was obtained. After purification at 60°C for 40 minutes with 10wt% of NaOH in the amount of 6 ml/100 g biodiesel, the isopropyl ester with FFA contents, cloud point and pour point of 0.1±0.0 wt%, 4.0±0.0˚C and 1.0±0.0oC, respectively, was obtained. For comparison, the esterification at 60˚C for 2 hour of PFAD with methanol at 1:8 molar ratios and 3wt% of conc. H2SO4, the biodiesel with FFA contents, cloud point and pour point of 1.6±0.01 wt%, 24.0±0.0˚C and 12.0±0.0oC, respectively, was obtained. After purification at 60°C for 40 minutes with 10wt% of NaOH in the amount of 4 ml/100 g biodiesel, the methyl ester with FFA contents, cloud point and pour point of 0.2±0.0 wt%, 18.0±0.0˚C and 11.0±0.0˚C, respectively, was obtained.