When biomass is converted into biodiesel, huge amounts of glycerol are produced as a by-product. So far, however, this by-product has been little utilised, even though it could be processed into more valuable chemicals through oxidation in photoelectrochemical reactors. The reason for this: low efficiency and selectivity. A team led by Dr Marco Favaro from the Institute for Solar Fuels at HZB has now investigated the influence of electrolytes on the efficiency of the glycerol oxidation reaction. The results can help to develop more efficient and environmentally friendly production processes.
In 2023, around 16 billion litres of biodiesel and HVO diesel were produced in the European Union*, based on maize, rapeseed, or partially on waste materials from agricultural production. A by-product of biodiesel production is glycerol, which can be used as a building block for the production of valuable chemicals such as dihydroxyacetone, formic acid, glyceraldehyde and glycolaldehyde via a glycerol oxidation reaction (GOR). Glycerol can be oxidised electrochemically in (photo)electrochemical (PEC) reactors, which are currently being developed in particular for the production of green hydrogen. However, this path in PEC-plants is still hardly exploited at present, even though it could significantly increase the economic efficiency of the PEC Power-to-X process, since the oxidation of glycerol requires a much lesser energy input than hydrogen production through water splitting, but at the same time produces more valuable chemicals.
Many studies have already investigated the role of photocatalysts in PEC electrolyzers, while the role of the electrolyte had not yet been systematically analysed. A team led by Dr Marco Favaro at the Institute for Solar Fuels has now unveiled the influence of electrolyte composition on the efficiency and stability of the glycerol oxidation.
Read more on HZB website
Image: The glycerol’s hydroxyl groups are attracted to the Bi3+ ions on the surface of the BiVO4 photoanode. The electrolyte plays a decisive role in mediating these interactions.
Credit: HZB