Electroorganic Synthesis for the Conversion of Fatty Acids and Levulinic Acid into Chemicals and Alternative Fuels

Abstract

The present work focuses on electroorganic synthesis for the conversion of biomass derived feedstocks into chemicals and fuels. The research of alternative fuels presents some peculiarities, especially the uncertainty regarding the requirements for prospective fuels from the chemical point of view. In this context, the present work discusses key properties for an initial fuel characterization and reinforces the importance of understanding the chemical structure of products from fossil and renewable biomass sources. This assessment aims to provide an alternative for the evaluation of the suitability of a chemical compound as fuel in an early stage research. The development of a suitable and flexible concept for the chemical analysis of the compounds involved in the electrochemical reactions is a fundamental part of the present work. The developed concept enables the evaluation of different electrochemical reactions. Lipids and levulinic acid are important products and feedstock of biorefineries, they have been therefore chosen as basis for two different electroorganic pathways investigated in this work. The first pathway has investigated the decarboxylation of fatty acids based on the non-Kolbe electrolysis. The second approach presents the primary and secondary conversion of levulinic acid by means of electrochemical oxidation and reduction at room temperature using water as solvent. The formed products may find either direct application as fuel, solvent or as intermediates for further reactions. The choice of the electrolyte composition and electrode material has shown a strong influence on the selectivity of the product formation. For some of the reactions the main product is insoluble in the electrolyte solution, which allows a direct separation of the product and the electrolyte reuse in a semi-continuous process. The use of a flow reactor is a important step for the upscaling, but for the investigation of unknown reactions it still presents some limitations. A comparison of the electric energy input with the heating values of the products on the example the decarboxylation of long chain fatty acids indicates that electroorganic conversion may provide an interesting and potentially energetically competitive process.