Vegetable oils as biodiesel feedstock

Pure plant oils (PPO) can be used directly as a starting material for biodiesel synthesis via transesterification. To reduce free fatty acids, raw materials containing such are submitted to an esterification step prior to transesterification. 

Type of oil Melting range (°C) Oiljfat FAME Iodine value Cetane number CFPP (FAME) Saturated fatty acids (%) 

Palm Petroleum diesel fuel 30-38 14 44-54 65 min. 51 10-14 DIN EN 590 -20 -10 0 seasonal Winter -20 transition -10 summer 0 45 

CFPP = cold filter plugging point, DIN EN 14214, the temperature at which a fuel will cause a fuel filter to plug due to fuel components, which have begun to crystallize or gel. 

RME is biodegradable and non-toxic. The flash point of 130 °C (compared to 55 °C for PD) ensures a safe storage. Compared to petroleum fuels RME has a more favourable combustion emission profile such as low emissions of carbon monoxide, sulphur and particulate matter. As a consequence of the so-called NOx-particle trade-off phenomenon, emissions of NOx are increased. Mutagenicity of RME emissions, however, is much lower compared to PD indicating a reduced health risk from cancer.  

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