Description
In order to achieve considerable CO2 reductions there is an urgent need to develop alternative sustainable processes based on bio-based feedstock and renewable energy. Levulinic acid (LA) is one of the renewable platform chemicals and can be electrochemically reduced in one step to valeric acid, a chemical currently produced via hydroformylation of fossil-based 1-butene. The high overpotential metal Pb enables selective formation of valeric acid (VA) with γ-valerolactone (gVL) being a minor by-product. [1-5] Recently, we have demonstrated the viability of other high overpotential metals (In, Cd and Zn) and studied the influence of reaction conditions such as pH, temperature and concentration of LA. To design a cost-effective electrochemical reactor it is also of importance to have insight on the reactions at the other electrode, i.e. the anode. Therefore the following questions related to the anode were addressed:• What is the reactivity of the reactants and products at the anode?
• What is the corrosion rate of the anode?
o Does LA have an influence on the corrosion rate?
o What is the influence of the dissolved metals on the cathodic reaction?
• What is the influence of anode type and cell design on energy usage?
Pb-based and a Dimensional Stable Anodes (DSA) were compared as these are industrially used in various electrochemical processes. LA, VA and gVL are slightly degraded at the Pb-based anode, whereas no degradation of these compounds was observed when using DSA type anodes. In addition, the potential of the Pb-anode is significantly higher than the DSA indicating an increased energy usage with Pb-based anodes. The stability of DSAs is underlined with an initial corrosion rate, which is three times higher compared to Pb-based anodes. Corrosion of the DSA, which contains iridium oxide as catalyst, results in the dissolution of a low amount of iridium during operation. To determine the influence of iridium on the cathodic process, a low amount of iridium was introduced into the catholyte solution. As a result iridium is deposited on the cathode, and the conversion of LA is lowered at an increasing amount deposited on the cathode. Similarly, the selectivity towards VA is decreased at increased loading of iridium on the cathode (see Figure 1). We tentatively explain this effect by the formation of iridium particles on the cathode that catalyse the reduction of protons to hydrogen.
| Period | 7 Mar 2023 |
|---|---|
| Event title | NCCC, The Netherlands' Catalysis and Chemistry Conference XXIV |
| Event type | Conference |
| Location | Noordwijkerhout, NetherlandsShow on map |