Electrosynthesis of basic chemicals

Challenge and concept

The energy transition in Germany (Energiewende) is in full swing and the associated expansion of wind and solar power is further increasing the supply of electricity from fluctuating sources. In periods of low demand for electricity, the excess supply of electrical energy can be alternatively used for the production of value.

Decentralized production of value chemicals from CO2 and air

Particularly promising is the production of carbon-based chemicals from water (H2O) and carbon dioxide (CO2), which is in this case not emitted as climate-damaging exhaust gas but be used as a raw material. In addition, electrosynthesis processes can also be used on a smaller scale for the decentral production of locally required basic chemicals. This makes consumers, such as hospitals, independent of suppliers and possible delivery bottlenecks. An important application in this case is for example the production of hydrogen peroxide from air/oxygen (O2) and water.

Electrochemical reduction of the gaseous educts on a gas diffusion electrode

Both the generation of carbon-based basic chemicals and the production of hydrogen peroxide are based on the same concept: The gaseous educts (CO2 or oxygen) are electrochemically reduced at a gas diffusion electrode (GDE) and react with water to form the desired, higher-value product. In order to further improve the CO2 balance, these electrosynthesis units can each be operated with electricity from renewable sources.

© Fraunhofer IGB
Electrochemical cell for CO2 reduction.

Our service offer

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

Fraunhofer IGB develops innovative (gas diffusion) electrodes, flow cells and prototypes for the electrochemical production of basic chemicals. The cells can be adapted to the customer's specific needs by choosing the appropriate electrodes.

Fully automated demonstrator for customer-specific tests

In addition, the IGB has designed and built a fully automatic demonstrator within the lighthouse project "Electricity as a Raw Material", with which reliable statements about upscaling, efficiency and long-term stability of the respective process under industrial operating condition can be made. This demonstrator is available for customer-specific tests.

Electrochemical and material-based evaluations of cells and electrodes

In addition to the development of the above-mentioned proprietary components, the IGB is also able to carry out electrochemical and material-based evaluations and tests on cell systems and electrodes developed by customers. A wide range of physical/chemical methods is available for this purpose.

Application examples

Electrosynthesis of ethylene from CO2

As part of the lighthouse project "Electricity as a Raw Material", Fraunhofer IGB has successfully demonstrated an electrosynthesis process for the direct production of ethylene from CO2 and water. For this purpose, an electrode with a surface area of 130 cm2 covered by a catalyst, which was developed and fabricated in-house, was used in a flow-through operation mode. By now, ethylene concentrations of 1700 ppm in the product gas were achieved with a Faraday efficiency of up to 8.5 percent. According to the current state of science and technology, comparable values are typically achieved on a laboratory scale, with electrode areas of only 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 continuously adjusted and monitored in order to optimize the technology and process and to make statements about efficiency and long-term stability.

Electrosynthesis of hydrogen peroxide from air/oxygen

Hydrogen peroxide (H2O2) is an essential component of disinfectants and, e.g., used as a bleaching agent. On a large scale, H2O2 is produced using the anthraquinone process and usually sold as a highly concentrated solution. This involves transport costs and safety precautions for the user. In addition, the dependence on suppliers for this critical component can lead to serious problems in form of delivery bottlenecks in times of crisis.

Therefore, especially for applications requiring recipes moderate hydrogen peroxide concentration (e. g. 3% and less), the on-site electrochemical production meeting these special requirements is a viable option. Consequently, the user is independent of possible delivery constraints and able to produce his own formulations flexibly.

With the electrolytic module developed by Fraunhofer IGB, essentially only air/oxygen, water and electricity are required for H2O2 production. In previous studies, we have already been able to achieve hydrogen peroxide concentrations of 3 g/L. The focus in current and upcoming projects is to further increase this concentration, to develop the process for further applications and their basic conditions (e.g. H2O2 production in different media) and to implement the process in fully automated prototypes meeting the specific requirements of the customer.

Reference projects

CELBICON –

Cost-effective CO2 conversion into chemicals via combination of Capture and ELectrochemical and BIochemical CONversion technologies

 

The aim of the CELBICON project is the development of new "CO2-to-chemicals" technologies. This goal is achieved by the combination of absorption of CO2 from the air, electrochemical CO2 conversion to C1 intermediates and a final fermentation of the intermediates to high-quality chemicals.

 

Duration: March 2016 – January 2020

Fraunhofer Lighthouse Project "Electricity as a raw material"

 

A new approach to use fluctuating excess electricity from renewable energies is to produce chemicals. This makes the electrochemical synthesis of chemicals not only economical, but also represents – in addition to store electricity – a sensible utilization path to compensate for electricity oversupply. In the Fraunhofer lighthouse project "Electricity as a raw material", Fraunhofer IGB is developing an electrochemical process for the production of ethene in just one process step.

 

Duration: August 2015 – September 2018

OxFloc – Integrated water treatment in a one-stage oxidative-adsorptive process to degrade and remove harmful substances

 

The OxFloc project is concerned with water treatment, aiming to degrade and remove hazardous substances in an integrated approach using a one-step oxidation-adsorptive process. This will not only reduce the operating costs of waste water treatment in the future, but also provide a substantial environmental benefit.

 

Duration: September 2013 – August 2015