(145g) Biodiesel Production As a Case Study in Chemical Engineering Senior Laboratory at University of Delaware

Transportation accounts for nearly thirty percent of energy used in the United States, and the majority of that energy is sourced from petroleum-based liquid fuels. Offsetting some of these petroleum products with renewable fuels has a number of environmental benefits. One alternative that has been investigated is “biodiesel,” or fatty acid methyl esters (FAMEs) that can be produced from a plant-based feedstock, such as vegetable cooking oils.

Because the production and analysis of biodiesel requires a number of principles from chemical engineering, including mass/energy balances, thermodynamics, and reaction kinetics, it provides an excellent case-study for senior-level chemical engineering students. At the University of Delaware, we have one pilot-scale and one bench-scale biodiesel production system in place for student projects. Here, we present the results from a senior chemical engineering laboratory “special project” aimed at improving the product yield from our pilot scale biodiesel production system.

Biodiesel is produced in bulk by base catalyzed transesterification of triglycerides. In our system, approximately 90 lb of soybean oil is reacted with excess amount of methanol and potassium hydroxide catalyst to produce FAME, glycerol, and water. The aqueous phase (water, glycerol, methanol, and catalyst) is then decanted and the FAME is transferred to a wash tank. The FAME is washed with water to reduce the amount of any remaining impurities. The mixture is decanted again, where there is a clear “water” phase, a cloudy “emulsion” phase, and an oil phase. The oil is then allowed to dry under low vacuum overnight and removed from the system for analysis.

A team of four senior-level undergraduate students was tasked with improving the yield of the baseline process described above, in particular by reducing the amount of product that is lost in the “emulsion” phase. We guided the students through four objectives: (1) establishing a baseline process and detailed standard operating procedure (SOP), (2) developing a hypothesis for why there is significant product loss in the emulsion, (3) designing experiments and collecting data on the bench-scale system, (4) applying the results to the pilot-scale system. At the same time, we worked on the GC analysis with a purpose to validate/improve existing analysis tools and to better quantify main components such as FAME, glycerin and methanol in reaction mixtures.

In this talk we will discuss the learning objectives for the course, the experimental apparatuses we have available at UD for this task, the approach, methods, and results from the project, and suggestions for future educational projects using the bench-scale and pilot-scale biodiesel production systems.