UNS: RUI: Reactions, Mechanisms, and Intermediates in Hydrocarbon Fuel Oil Produced from Brown Grease: Important Information for Scale Up to Commercial Production.

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PI: Lawrence M. PrattProposal Number: 1507069Brown grease is a semi-solid mixture of fats, oils, and greases that collect in the sewage system and sewage treatment plants, and which must be collected and removed to prevent blockages, overflows, and damage to equipment. The volume of this waste, somewhere between one and two billion gallons per year, is sufficient to consider its recycling into liquid transportation fuel as opposed to incinerating it, which produces greenhouse gases. This goal of this project is develop a process to convert brown grease into a fuel similar to kerosene using a process called low-temperature pyrolysis, where the brown grease is heated up in absence of air. The research suggests that trace metals such as iron that are present in brown grease may promote the reaction process, and so the research plan will focus on determining which reaction steps in the overall process are catalyzed by these metals. The proposed research will be carried out by a team of undergraduate students at the Medgar Evers College of the City University of New York (CUNY), which is a minority serving institution. Benefits of this research include increasing the supply of non-fossil fuels, reduced greenhouse gas emissions, elimination of brown grease disposal problems, and training of underrepresented minority students in chemistry, energy, and environmental science. This project also has international collaborators from Malaysia and Vietnam that are interested in using the new technology to solve similar waste steam problems in their respective countries.Unlike triglycerides extracted from vegetable oils, brown grease is predominantly free fatty acids, and so cannot undergo the homogeneous transesterification to biodiesel. The overall goal of the proposed research is to develop a fundamental understanding of the reaction mechanisms for the low-temperature pyrolysis of brown grease to linear hydrocarbons. It is hypothesized that the reaction scheme proceeds by a two-step process were fatty acids in the waste stream are decarboxylated to ketone intermediates and then deoxygenated to hydrocarbons. Furthermore, it is hypothesized that soluble iron or copper present in the waste matrix catalyzes some of these reactions. The research plan has three objectives. The first objective is to elucidate the major reaction pathways from brown grease and model mixtures of the waste matrix to hydrocarbon products. The second objective is to determine how the principal metals found in brown grease catalyze these reactions. The third objective is to develop a continuous reaction process and assess the energy return on energy invested for sustainable energy concepts based on recovery and conversion of brown grease to fuel. The experimental approach will employ gas chromatography-mass spectrometry (GC-MS), differential scanning calorimetry (DSC), and thermogravimetric analysis to characterize the reaction system. Computational quantum chemistry will also be used to elucidate the reaction mechanisms and to help determine whether some compounds observed in the reaction mixture are byproducts or intermediates. Although the research focuses on brown grease, the research outcomes have potential to develop new routes and fundamental understanding for the chemical conversion of free fatty acids to fuel. The proposed research will be carried out by a team of undergraduate students at the Medgar Evers College of the City University of New York (CUNY), which is a minority serving institution.