Thesis (M.Sc.)--Chulalongkorn University, 2012

This research aimed to improve the cold flow property of biodiesel from sunflower oil (SW) and palm oil by using six synthesized pour point depressants (PPDs) which were methyl ester (ME), ethyl ester (EE), i-propyl ester (PE),2-butyl ester (BE), 2-ethylhexyl ester (EHE) and 1-dodecanol ester (DE). All of these PPDs were synthesized by transesterification reaction and characterized by IR and 1H-NMR techniques. By using these PPDs, at 300,000ppm the cloud point (CP) and pour point (PP) of biodiesel from sunflower oil was decreased in the range of 0.0±1.0°C to 14.8±1.0°C and 0.0±1.0°C to 7.7±1.0°C, as well as forbiodiesel from palm oil (PME) in the range of 2.3±1.0°C to 6.8±1.0°C and 3.4±1.0°C to 5.4±1.0°C, respectively. BE gave the best result on improving cold flow property of sunflower and palm biodiesel due to the steric hindrance of branched chain alcohol. At 300,000 ppm,BE could improve CP and PPfrom 14.8±1.0°C to 0.0±1.0°C and -11.0±1.0°C to -18.7±1.0°C for SWME andfrom 21.0±1.0°C to 14.2±1.0°C and 19.0±1.0°C to 13.6±1.0°C for PME, respectively.