Single-stage electrosynthesis of ethene from CO2

The use of carbon dioxide (CO2) to produce carbon-based basic chemicals using regenerative energy is a promising approach to reduce net CO2 emissions, conserve fossil resources and therefore reduce economic dependence on oil imports from outside Europe.

© Fraunhofer IGB

Demonstrator with the circuits to the electrolyte (left) and gas supply (right).

© Fraunhofer IGB

Electrochemical cell for CO2 reduction.

As part of the Fraunhofer Lighthouse Project "Electricity as a raw material", the electrochemical synthesis of ethene, one of the most important raw materials in the petrochemical industry, from CO2 and water was demonstrated. For this, Fraunhofer IGB has developed novel, efficient catalysts for the reduction of CO2 to ethene as well as the necessary gas diffusion electrode.

Automatic demonstrator with electrolytic cell

In addition, a demonstrator equipped with a process control system for fully automatic operation was designed and built. The core component is an electrolytic cell with an integrated gas diffusion electrode (GDE). With this demonstrator, the electrosynthesis process with an electrode area of 130 cm2 and in-house catalysts was investigated and demonstrated in flow-through operation. In recent studies we were able to achieve ethylene concentrations in the product gas of 1700 ppm, corresponding to a Faraday efficiency of 8.5 percent. According to the state of the art in science and technology, comparable values have so far only been achieved on a laboratory scale, with electrode surfaces of a few square centimeters.

The plant also allows the specific analysis of the products that are created in a gaseous or liquid form in each case. Further process parameters can be adjusted and monitored in order to optimize the technology and process and to be able to make statements about efficiency and long-term stability.

Adaptation to further electrosynthesis processes, screening, scale-up

With the system, results achieved on a laboratory scale so far can now be transferred to a first industry-relevant scale. Besides, the design of the demonstrator can also be transferred to other electrosynthesis processes and enables screening of catalyst and electrode materials as well as projections for the scale-up of the processes.