Monostearin effects on the formation of precipitate in palm oil biodiesel and petroleum diesel blends with various storage temperature

Abstract

Biodiesel is one of the renewable energy forms that is on demand in Indonesia. In the biodiesel production process, impurities such as Saturated Monoglycerides (SMG) in the form of monostearin that precipitate at low temperature are commonly formed. This is caused by high Final Melting Temperature (FMT) of SMG. Formation of solid deposits when it reaches a temperature above Cloud Point (CP) is then unavoidable under these conditions. The use of palm oil biodiesel and petroleum diesel blends (BXX) with biodiesel blend ratio of 10% (B10), 20% (B20) and 30% (B30) accelerates precipation process which renders clogging on fuel filters. These works examined the effect monostearin content and temperature on the precipitation rate. Investigation is carried out at 15°C, 20°C, 25°C, and room temperature (30-33°C) with varying content of monostearin (0.4%, 0.7%, and 0.9%). Early results show that for 0.4% monostearin content in 100 ml B20, the amount of precipitate formed at temperature 15 oC was 31.3 mg. This value was higher than that at room temperature (6.3 mg) after 2 weeks storage time. This value was higher compared to B20 (21.5 mg). This indicates that as the biodiesel ratio in BXX become higher, the amount of FAME will increase which effect monostearin solubility in BXX at low temperature.