Crystallization Behavior of Biodiesel and Biodiesel Blend

Jessica Sorensen, Jason Wall, Nestor U. Soriano, Jr.

Presented at the Poster Session at the Capitol Rotunda, Helena, MT and MSU Student Research Celebration, Bozeman, MT Research supported by NSF through the Major Research Instrumentation Grant

The poor cold-flow properties of biodiesel limits its utilization in cooler regions like Montana. Crystallization during cold-weather operations may lead to clogging of filters and eventually fuel starvation and engine stalling. This study aims to understand the crystallization behavior of biodiesel derived from different vegetable oils and animal fat. The cloud point (CP) and cold filter plugging point (CFPP) of biodiesel samples were determined according to ASTM methodologies. Crystallization of biodiesel was also observed under a Polarized Light Microscope (PLM). Lastly, the impact of commercial anti-gel agents on biodiesel, diesel fuel No.2 and biodiesel blends were evaluated.

Biodiesel crystallization is mainly influenced by the fatty acid profile of the feedstock. The presence of a high amount of mono-unsaturated components in canola biodiesel impedes agglomeration attributed to their bent structure. Turkey fat and coconut biodiesel both developed a thicker layer of solidified materials. Surprisingly flax, which contains a high amount of poly-unsaturated components, exhibited agglomeration leading to the formation of larger crystals. Canola biodiesel developed the smallest crystal size among all the biodiesel samples tested.

Diesel exhibited better cold-flow properties than biodiesel. A B20 (20% Biodiesel, 80% conventional diesel) blend exhibited a 35% increase in CP and CFPP compared to neat diesel. Diesel No. 2 had the tendency to develop a film rather than crystals at low temperatures. In general, effective anti-gels improve the cold flow of fuel by lowering a fuel’s CFPP and not the CP.