Biodiesel Fuels from Supercritical Fluid Processing: Quality Evaluation with the Advanced Distillation Curve Method and Cetane Numbers

The volatility of biodiesel fuel samples produced by supercritical (SC) transesterification (TE) of triglyceride feedstocks of chicken fat and soybean oil was determined by the advanced distillation curve (ADC) method. Particularly high temperatures (e.g., 400 °C) of the SCTE process partially decomposed the polyunsaturated fatty acid methyl esters (FAMEs) to lower molecular FAMEs (∼C 6 –C 15 ) and ∼C 10 –C 17 hydrocarbons. These lighter fuel components shifted the first portion of the distillation curves toward that of #2 diesel fuel. This means that biodiesel fuels produced by SCTE at ∼400 °C exhibit higher overall volatility when compared to commercial biodiesel samples produced by conventional catalytic TE. Other important fuel properties such as ignition delay via cetane numbers could also be improved. This information will permit efficient fuel system and combustion chamber designs to optimize fuel utilization in diesel engines, decrease of fuel consumption, and emission mitigation.