(16b) Kinetic Evaluation and Reactor Modeling for Transesterification of Lipids With Dimethyl Carbonate Using the Homogeneous Catalyst Triazabicyclodecene

The production of biodiesel, a mixture of fatty acid methyl esters, has grown over the last two decades. However, due to limited feedstock supplies, excessive amounts of process wash water, and a low-value byproduct (i.e. glycerol), the biodiesel industry, and renewable fuels industry as a whole, may see a decline in the coming years. A biofuel, similar to biodiesel, has been developed by replacing dimethyl carbonate (DMC) as an alternative to methanol as the methylating reagent in the transesterification reaction.  The rational behind using DMC was to develop a biofuel and a biofuel process that would eliminate the use of process wash water, have a completely recoverable catalyst, and would not produce any non-value byproducts, such as glycerol.  This work reports on a biofuel, analogous to biodiesel, that can be produced by reacting lipid oils with DMC, instead of methanol. The DMC reaction produces 2 FAMEs and 1 fatty acid glycerol carbonate (FAGC) for every triglyceride molecule converted.  This reaction scenario generates a more desirable product, without the glycerol byproduct, and at lower production costs. Experiments were conducted using canola oil, DMC, and triazabicyclodecene catalyst.  Products were first identified using GC/MS and were found to be fatty acid methyl esters (FAMEs) and fatty acid glycerol carbonates (FAGCs).  The FAGCs are miscible with FAMEs, and are, therefore, usable as a fuel.  The produced biofuel passed the ASTM D6751 standard for biodiesel.

            From our initial screening studies, triazabicyclodecene (TBD) was chosen as the catalyst due to its ability to easily ionize the dimethyl carbonate and relative ease of separation post reaction. We will report on the developments of this reaction scenario, including reaction kinetics, in situ FTIR and Raman spectroscopies of reaction intermediates, and the chemical process development using Aspen 7.1 simulation software