Improving cold flow property of biodiesel from white sesame seed oil

Abstract

White sesame seed oil (WSSO) was selected as feedstock for producing biodiesel because of high level of unsaturated fatty acid and high yield of oil. Due to its poor flow property at low temperature, this research aimed to improve the cold flow property of biodiesel from WSSO by using 16 types of pour point depressants (PPDs) as follows: methyl laurate (ML), methyl stearate (MS), methyl oleate (MO), methyl linoleate (MLN), isopropyl laurate (IPL), isopropyl stearate (IPS), isopropyl oleate (IPO), isopropyl linoleate (ILN), 2-butyl laurate (BUL), 2-butyl stearate (BUS),2-butyl oleate(BUO), 2-butyl linoleate (BLN), 2-ethylhexyl laurate (EHL),2-ethylhexyl stearate (EHS),2-ethylhexyl oleate (EHO) and 2-ethylhexyl linoleate (ELN). These PPDs were synthesized via esterification reaction. The structure of PPDs was characterized by 1H-NMR and FT-IR techniques. Biodiesel from WSSO was synthesized via transesterification reaction. Its structure and composition were characterized by 1H-NMR and GC-FID techniques. At 300,000 ppm, the cloud point (CP) and the pour point (PP) of biodiesel from WSSO were reduced in the range of 6.50 ± 1.0°C to 8.20 ± 1.0°C and 7.00 ± 1.0°C to 9.50± 1.0°C, respectively when using ML, IPL, BUL, EHL, MO, IPO, BUO, EHO, MLN, ILN, BLN and ELN as PPDs while MS, IPS, BUS and EHS could not improve its cold flow property. At 300,000 ppm of BUL, the CP and the PP of biodiesel from WSSO were reduced by 8.20 ± 1.0 °C and 9.50 ± 1.0 °C, respectively. The results indicated that BUL was the most effective PPDs when compared with other PPDs due to the steric hindrance in its structure.