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Pictures of the Future
The Magazine for Research and Innovation

Materials Science and Processing

Transforming Carbon Dioxide into a Key Industrial Ingredient

Two research projects that are being conducted jointly by Siemens and Evonik aim to produce valuable substances from carbon dioxide. Silver-based electrodes enable an electrolytic process to produce carbon monoxide, which is a starting material for specialty chemicals, while copper-based electrodes enable it to create ethylene.

Carbon dioxide does not have a very positive image, as it is mainly regarded only as the cause of climate change. However, experts at Siemens can also use the gas for beneficial purposes. Siemens is working together with the chemical company Evonik, which is based in North Rhine-Westphalia, on two government-funded projects that are using CO2 to produce valuable basic and specialty chemicals for industry. The scientists expect to gain important insights that will enable them to gradually provide electrochemical synthesis processes for large-scale industrial applications.

Rheticus: Converting CO2 into Specialty Chemicals

In January Siemens and Evonik presented a new joint research project called Rheticus. In the project, approximately 20 experts from both companies are working to generate valuable specialty chemicals from CO2. The first phase of the project will end in 2019, and plans call for the completion of an initial test facility at the Evonik location in Marl two years later.

How does the process work? In the first step, a Siemens electrolyzer uses renewable energy to convert carbon dioxide and water into metabolizable carbon monoxide (CO). Next, a fermentation process from Evonik very selectively converts the gases containing CO into valuable substances with the help of special microorganisms. The end products are chemicals such as butanol and hexanol, both of which are starting materials for products such as specialty plastics and food additives.

“We are currently operating experimental setups,” says Günter Schmid, who is responsible for electrolyzers at Corporate Technology. “This is where we can test and optimize our electrolysis cells and gas diffusion electrodes.” The aim of the project is to scale the technology from lab dimensions to those of a technical testing facility by 2021. The Rheticus facility is expected to have a production capacity of 10 to 20 tons per year. This would make it possible to build an industrial plant with a production capacity of up to 20,000 tons of butanol or hexanol per year. “We’re also discussing the possible production of other specialty chemicals or even fuels,” Schmidt adds. Depending on the needs of future customers, the dimensions of the Rheticus platform could also be expanded.

Rheticus is part of the Copernicus Initiative for Germany’s energy transition. The initiative aims to find new solutions for converting the country’s energy supply system. The German Federal Ministry of Education and Research (BMBF) is providing Rheticus with €2.8 million in funding.

Siemens researchers in the Rheticus research project are working to generate valuable specialty chemicals from carbon dioxide. Elena Volkova is preparing electrodes, a cell, and a set of operating parameters for a new series of tests.

eEthylene: CO2-neutral Production

In the government-funded eEthylen project, experts from Siemens are working together with scientists from Evonik, Berlin Technical University, Ruhr University Bochum, and the Helmholtz Institute Erlangen-Nuremberg to study how the greenhouse gas CO2 can be converted into ethylene. “We are convinced that not only will the greenhouse gas help to produce coveted materials, but that CO2 will also open up new business opportunities for Siemens,” says Dan Taroata, a project manager at Siemens, the leader of the consortium.

In a direct, single-stage electrolysis system, the researchers are using electricity to synthesize ethylene out of carbon dioxide and water. Their work focuses on electrocatalysts, because these materials can charge the inert CO2 with energy-rich electrons in order to create ethylene. If the electrons cluster in the surrounding water instead, the process only creates hydrogen. That’s why the catalyst plays a decisive role in the method’s success. However, it is a great technological challenge to find a stable cupriferous electrode for the production of ethylene.

The use of an appropriate catalyst ensures the electrochemical synthesis of ethylene from carbon dioxide and water; otherwise electrolysis produces only hydrogen.

Electrolyzers - a core area of expertise at Siemens

For the CO and ethylene production process, Siemens is contributing a system from one of its key areas of expertise: an electrolysis facility for continuous operation. It is based on electrolyzers for hydrogen production, which are already part of the Siemens product range today.

The project receives funding from the German Ministry of Education and Research and is part of the CO2Plus research initiative for the use of CO2 to broaden the base of raw materials. Siemens is the leader of the project consortium. The three-year project was launched in October 2016. Provided with a total budget of €2.9 million, eEthylen could well revolutionize ethylene production. The aim is to find out how the greenhouse gas CO2 can be efficiently converted into valuable ethylene.

Simple and Inexpensive Ethylene Production

Ethylene is currently used in a wide variety of ways. For one thing, it is the starting material for the production of polyethylene, polyvinylchloride, and polyester. As such, it is contained in most plastics. Ethylene also helps to make fruits and vegetables ripen at precisely the right time — an important application in a world of globalized food-supply chains.

If the research team succeeds in optimizing the electrolytic production process, it could become a serious competitor of the conventional manufacturing method. Besides using atmospheric CO2 and thus being desirable from an environmental perspective, this process would also be worth pursuing from a business point of view. That’s because one ton of ethylene costs between €850 and €1,200 — a hefty sum, considering that around 180 million tons are used annually worldwide.

Ulrich Kreutzer
Picture credits: Video: ERBSE DESIGN