High Temperature and Pressure Alkaline Electrochemical Reactor for Conversion of Power to Chemicals

Moving away from fossil fuels requires harvesting more and more intermittent renewable energy resources and establishing a sustainable system for the production of chemicals. This brings forward the need for efficient large scale energy storage technologies 1-3 and technologies for the conversion of renewable electricity to chemicals.

Electrochemical reactors can play a crucial role in this endeavor, since they can efficiently and reversibly transform electricity to high-value chemicals, and thus serve as energy storage and recovery devices for balancing the grid, while offering a means for the sustainable production of chemicals 4-6.

A novel type of alkaline electrochemical cell that can operate at elevated temperature and pressure has been developed that relies on corrosion resistant high temperature diaphragms, based on mesoporous ceramic membranes where aqueous KOH is immobilized by capillary forces. Raising the operating temperature offers a means to boost performance, as both ionic transport and reaction kinetics are exponentially activated with temperature.

Indeed, we have demonstrated alkaline electrolysis cells operating at 200-250 °C and 20-50 bar at very high efficiencies and power densities. This work will provide an overview of our efforts to develop components of such high temperature alkaline electrochemical reactors for different applications.

Low-cost large-scale production methods have been successfully employed for the production of ceramic diaphragms and full cells. The influence of composition and microstructure on the long-term chemical stability and mechanical durability of the mesoporous ceramic membranes has been explored. Instrumentation for electrochemical testing at elevated pressures (up to 99 bar) and temperatures (up to 300 °C) with in-line chemical analysis has been established enabling experiments with gaseous or liquids reactants/products at cell sizes of up to 25 cm2.

Efforts are currently directed towards the investigation of the intrinsic activity of mixed oxides for the oxygen evolution reaction at elevated temperatures and pressures, and of the intrinsic activity, selectivity and stability of supported metal catalysts towards the electrocatalytic conversion of biomass derivatives to high-value chemicals.

Finally, the use of selected electrocatalysts for the production of high performance electrodes will be reported.