Alternative fuels derived from biomass “biofuels” are an attractive alternative to substitute limited and non-renewable sources of energy. Bio-oil generated from the pyrolysis of biomass is a complex micro-emulsion with high levels of oxygen and acids, which lead to increases in viscosity, phase separation, and degradation as it ages. This instability of bio-oil complicates storage, transportation and downstream processing. Currently, catalytic upgrading of is performed to stabilize the bio-oil by means of the reduction of the oxygen content. However, the current hydrothermal upgrading technologies operate at high hydrogen pressures, up to 2000 psi, and temperatures that lead to coke formation in the catalyst bed. A milder method is needed to convert unstable carbonyl species to more stable alcohols as an intermediate step before hydrothermal treatment.

In this work an electrochemical approach has been investigated for the upgrading of bio-oil at low temperature using a proton exchange membrane (PEM) electrolyzer. The PEM electrolyzer was selected for performing the conversion as it avoids the need to add electrolyte to the oil which would cause phase separation and require later removal. Work has primarily focused on using cation-exchange membranes where protons are generated in the anode and travel through the membrane to the cathode surface. The hydrogenation of the bio-oil at the cathode competes with hydrogen evolution. Work has focused on using various electrode cell architectures and electro-catalysts to reduce both model compounds and actual pyrolysis oil derived from wood. 

While further work is needed, promising results have been observed with reduction of carbonyl groups and phenolic rings. A description of the work conducted and discussion of the results will be presented.