LAUSR

Abstract Brown grease breaks down into a mixture of alkanes and alkenes at temperatures above 300 °C without addition of hydrogen or an external catalyst. To better understand the reactions in this process, pyrolysis experiments were performed on palmitic and oleic acids as model systems for the saturated and unsaturated fatty acids in brown grease, respectively. Iron (III) sulfate was used in half of the experiments, as Fe(III) is normally found in brown grease; and the other experiments were performed without iron as controls. In the presence of Fe(III), palmitic acid forms a series of aliphatic hydrocarbons and some palmitone byproduct, while the iron-free control experiment yielded larger quantities of palmitone, up to more than 50%. However, regardless of Fe(III), oleic acid broke down into shorter saturated fatty acids, hydrocarbons, alcohols, aldehydes, esters, and ketones, according to known thermal reactions of unsaturated fatty acids. The product fatty acids then reacted in a manner similar to palmitic acid. The major ketone and alcohol byproducts were also examined for reactions ultimately leading to the desired products.