Electrochemical decarboxylation of carboxylic acids over platinum surfaces for bio-oil upgrading

To mitigate global warming and reduce its impact on our climate, alternative, clean and renewable energy sources must be harnessed to replace fossil fuels. As fluctuations in availability of sun and wind causes technological limitations for solar and wind energy, energy from biomass is explored as well. Biomass can be converted into bio-oil via fast pyrolysis. Raw bio-oil typically contains a wide variety of organic compounds, including carboxylic acids which results in a high corrosivity and low thermal stability. Upgrading processes are required to increase the quality of bio oil. As traditional upgrading technologies operate at high temperatures and pressures, electrochemical techniques are an appealing alternative. Electrochemical decarboxylation of carboxylic acids (also referred to as Kolbe electrolysis) has been proposed to produce valuable compounds while upgrading bio-oil.

This dissertation investigates and discusses the electrochemical decarboxylation of short-chain carboxylic acids on platinum anodes under various reaction conditions. The primary aim was to understand the chemical transformations occurring on Pt electrodes, depending on the electrolyte pH, the nature of the carboxylic acid, and morphology of the Pt electrode. In addition, the feasibility of using low loading Pt electrodes to reduce electrode material costs has been discussed and pulsed electrolysis of mixtures of carboxylic acids were used to improve product yield and alter product selectivity. Overall, the aim was to increase the economic viability of electrochemical decarboxylation for bio-oil upgrading.