Separation And Use Of Oxygenated Byproducts From Non-Catalytically Cracked Triglycerides And Their Methyl Esters
Date of Award
Master of Science (MS)
The world is dependent on petroleum as its main source of fuels and chemicals. Supply limitations and global warming have generated a great deal of interest in research to reduce this dependence through renewal fuels and chemicals.
Non-catalytic cracking and subsequent distillation of triacylglyceride (TAG) oils and methyl esters derived from these oils (TMEs) produces an organic liquid product (OLP) that is rich in potential fuels and chemicals. A major fraction of the OLP is made up of oxygenated compounds, either short chain fatty acids (SCFAs) if TAG oil is cracked, or short chain methyl esters (SCMEs) if TMEs are cracked. These oxygenated byproducts are substandard fuel components compared to hydrocarbons. However, the SCFAs and SCMEs are valuable as byproducts in a bio-refining scheme. It is therefore desirable to separate and recover these compounds as usable byproducts.
Separation of the SCMEs from TME-derived OLP was explored using batch liquid -liquid extraction experiments with polar solvents. Additionally, continuous multistage extraction was modeled. The partial mutual miscibility of the hydrocarbon and polar phases complicated the results and created inaccuracies in modeling. Despite this, it was determined that acetic acid was the most successful solvent, reducing the SCME concentration by 23% in a single stage extraction while allowing only 10% of the hydrocarbons to overlap into the polar phase. An 88% SCME reduction was calculated as a rough estimate for a 20 stage extraction using a solvent to OLP flow ratio of 3:1. It is unclear how the phase overlap will effect multistage extraction, so future multistage LLE experiments are recommended to determine if this method is commercially viable.
Acetic acid, an SCFA, is one of the most abundant oxygenated products in cracked TAG oil. Its recovery and use as a byproduct were studied at the bench scale. The acetic acid was successfully separated from cracked TAG oil distillates using liquid-liquid extraction with water and then purified via azeotropic distillation. About 1.6 L of approximately 99 wt% pure acetic acid was produced from 250 L of soybean oil using this process.
The acetic acid was reacted with ethylene over a palladium (Pd) catalyst to produce renewable vinyl acetate monomer (VAM). The VAM was purified using batch distillation to about 99 wt%. This work successfully demonstrated that a renewable product generated from TAG oil cracking is chemically identical to its petroleum derived analog. This product is projected to be interchangeable with the current standard.
Jones, Benjamin Travis, "Separation And Use Of Oxygenated Byproducts From Non-Catalytically Cracked Triglycerides And Their Methyl Esters" (2012). Theses and Dissertations. 1355.