(769f) Transesterification of Soybean Oil with Microwave Heating Using Homogeneous and Heterogeneous Catalysts

Authors: 
Gilbert, C. J., University of Massachusetts-Amherst
Conner, W. C., University of Massachusetts-Amherst
Huber, G. W., University of Massachusetts - Amherst


The finite supply of petroleum-based fossil fuels has prompted research into the production of fuels from renewable feedstocks (such as biomass). One of the fuels that are obtained from a biomass-based feedstock is biodiesel, which is produced by the transesterification of triglycerides or the esterification fatty acids. This fuel can be blended with diesel fuels and used in a conventional diesel engine, or it can be used alone as fuel in a properly modified engine.

The transesterification reaction starts with a triglyceride molecule (a three-chain fat, commonly found in oils), and removes the fat chains and converts them into biodiesel esters (by reaction with methanol) in successive steps. It is typically base catalyzed using homogeneous catalysts, the two most common industrial catalysts being sodium methoxide and sodium hydroxide. Unfortunately, the use of homogenous catalysts for this reaction requires significant neutralization and washing of the product stream. As an alternative to these catalysts, the heterogeneous catalyst strontium oxide is also examined. In this work, we consider how these catalysts behave under microwave irradiation and compare this heating method to conventional heating.

As well as examining the effects of heating on both homogeneous and heterogeneous catalyst, we will perform a kinetic fitting of the system. We will develop a model that incorporates the three individual steps of the reaction, and fit experimental data to determine the rate constants and activation energies of each of the steps. The ratios between these rate constants for different catalyst will also be considered. Lastly our model will also incorporate the inherent starting biphasic nature of the system (methanol and triglycerides are effective immiscible).

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