Improving the cold flow behavior of methyl biodiesel by blending it with ethyl esters

Blending biodiesels is a well-established approach for the lowering of cloud and pour points. The use of ethylic biodiesel, with better cold weather properties due to the lower melting points of ethylic esters, could be another interesting alternative, promoting the utilization of more saturated oils and fats. To study that possibility this work evaluated the melting behavior of 3 mixtures of esters composed of ethyl palmitate, ethyl stearate or ethyl oleate with methyl palmitate. These esters are based on some of the most abundant fatty acids present on soybean and palm oils, two of the most expressive vegetable oils sources for biodiesel production. The solid-liquid phase diagrams in the entire concentration range of these 3 systems were evaluated with all phase transitions reported. The systems composed of saturated ethyl/methyl esters showed a very complex behavior, with the formation of solid solutions (organic alloys), peritectic reactions, and metatectic transitions. The liquidus lines of these systems were compared with the equivalent mixtures based on methyl esters alone showing that lower melting temperatures were achieved. Therefore blends between ethyl esters and methyl esters are suggested to improve the low temperature behavior of biodiesels. (AU)