CO2 as a raw material for sustainable chemistry

In order to stop further global warming, greenhouse gas emissions must be urgently avoided through savings in resource consumption and increased efficiency, but also by replacing fossil raw materials with renewable alternatives. One possibility is to use the greenhouse gas CO2 itself as a raw material for carbon-based products. At Fraunhofer IGB, we are pursuing various technological approaches to activate the inert CO2 molecule and subsequently use it to synthesize a variety of chemical products – from bulk to fine chemicals, from fuels to plastics.

 

Carbon is ubiquitous in the biosphere and a central building block of all organic matter. But carbon is also the basic element of numerous materials in everyday products – from fuels and plastics to cosmetics and pharmaceuticals. Currently, these are mainly produced from fossil raw materials such as oil and natural gas.

Due to the advancing climate change with increasingly dramatic consequences, greenhouse gas emissions must be avoided urgently, through savings in resource consumption and increased efficiency, but especially by replacing fossil raw materials with renewable alternatives. The transition from fossil fuels to renewable energy and raw materials is known as defossilization or defossilation. 

 

Fraunhofer IGB – Partner for the defossilization of your processes

Fraunhofer IGB supports you in developing processes and process cascades that can be used to produce fuels, platform chemicals, plastics and other chemical products from renewable resources in a climate-neutral way.

CO2 – from greenhouse gas to resource

Carbon dioxide (CO2) is increasingly seen not only as a climate-changing  greenhouse gas, but also as a promising carbon source for the synthesis of a wide range of chemical products – in other words, as a raw material. The corresponding general approach of Carbon Capture and Utilization (CCU) is about binding the carbon in CO2 in products through technical conversion processes. 

 

Circular carbon economy through recycling CO2

CO2 is produced during all combustion and oxidative degradation processes of organic materials, such as microbial decomposition of biogenic substances, our respiration and alcoholic fermentation. The greenhouse gas CO2 is therefore unlimitedly available and can be utilized as raw material for innovative process technologies, driven by renewable energy. Reuse of carbon in the form of CO2, known as chemical carbon recycling, helps build a sustainable circular carbon economy and reduce the use of fossil resources. 

 
Auch in Brauereien entsteht Kohlendioxid.
Carbon dioxide is also produced in breweries.
Relevant point sources of CO2 are process gases from breweries, waste incineration and biogas plants, cement works and blast furnaces in the steel industry.

How to successfully reuse CO2

CO2 is a low-energy and chemically quite inert compound that can only be induced to a chemical reaction with high energy input and suitable catalysts. As the energy transition progresses, renewable energies are increasingly available to chemically activate CO2 and use it as a sustainable carbon source. 

In a first step, CO2 must be separated and purified from industrial process gases (so-called point sources) or directly from the air (direct air capture, DAC). Relevant point sources are, for example, process gases from breweries, waste incineration and biogas plants, cement plants or blast furnaces in the steel industry. 

 

Sector coupling through chemical energy storage

With just a few chemical or electrocatalytic conversion steps, basic chemicals (e.g., methane, methanol, ethene) or synthetic fuels can be produced from CO2. Compounds such as methane or methanol are also easy to store and transport and can function as chemical energy carriers/storage media. For this reason, they play an essential role in the energy transition and link the energy sector with the chemical and transport sectors.

CO2 conversion technologies and products made from CO2

Fraunhofer IGB pursues various approaches to convert CO2 and offers intelligent solutions for the production of a wide variety of products from CO2 through advantageous combination of (electro-)chemistry, process engineering and synthetic biotechnology. Our goal is to further develop these technologies into economically viable processes in collaboration with our industrial partners. 

CO2 conversion technologies and products from CO2

 

Basic chemical methanol

Chemical conversion of CO2 with hydrogen

We are researching thermocatalytic methanol synthesis from CO2 in order to be able to use CO2 from industrial point sources (exhaust gases from cement plants, biorefineries, etc.) with the help of resilient catalysts.

 

Sustainable transportation sector

Synthetic fuels

At the Straubing branch of the institute, we are working on the development of processes for the production of synthetic fuels from CO2. Alcohols produced from CO2 and hydrogen, primarily methanol, are converted into light alkenes (olefins), from which so-called middle distillates are obtained by oligomerization and hydrogenation, i.e. fuels in the range of diesel and kerosene.

 

Synthesis gas

Plasma splitting of CO2

In this approach, CO2 is energetically split into CO and O2 in a plasma. A new type of ceramic membrane separates O2 and prevents the reverse reaction. The perovskite capillary membrane can withstand plasma temperatures of up to 1000°C and high CO2 concentrations. The plasma membrane process can be used directly where CO2 is produced.

 

 

Basic chemical formic acid

Electrocatalytic conversion of CO2

The direct electrocatalytic reduction of CO2 in an electrochemical cell offers an attractive alternative to chemical conversion with H2. At the IGB, we concentrate on the electrocatalytic synthesis of formic acid and its salts, for which we use gas diffusion electrodes coated with various electrocatalysts.

 

Monomers for plastics

Power-to-X-to-Y cascade processes

We combine Power-to-X with industrial biotechnology to create Power-to-X-to-Y process cascades. In this way, the recycling of CO2 is no longer limited to the synthesis of basic products ("X") such as methanol or formate. Rather, these can serve as raw materials for future (bio)refineries in which more complex and valuable platform chemicals ("Y") are produced.

 

Recyclable materials from biomass

Biotechnological recycling of CO2

Microalgae produce ingredients from CO2, light and minerals. We are developing technologies and value chains to harness the potential of land-independent, decentralized microalgae production for the food, cosmetics, plant strengthening and textile industries. Algae production can be linked to CO2-emitting industrial processes.

 

Fine and specialty chemicals

Electrobiocatalytic fixation of CO2

Electrobiocatalytic synthesis modules allow the combined use of regenerative electricity, CO2 and individual enzymes or enzyme cascades, following the example of nature. In our synthesis module, selective NADPH-dependent CO2 fixation and the enzymatic cofactor regeneration of NADPH take place.

 

 

Scaling and piloting

Scaling of processes for the utilization of CO2

At Fraunhofer CBP, we develop and scale up chemical processes for the conversion of CO2 and H2 to basic chemicals, fuels and combustibles and demonstrate and optimize them in pilot plants together with our partners.

Further information

 

Dossier

Biotechnological CO2 recycling

Comprehensive dossier on CO2 as a raw material on the BMBF online portal Bioökonomie.de with five IGB projects

 

Title: Carbon source CO2

Carbon dioxide: turning the problem around

Fraunhofer magazine
1/2024

Arne Roth

Contact Press / Media

Dr. Arne Roth

Head of Department Sustainable Catalytic Processes

Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB
Schulgasse 11a
94315 Straubing

Phone +49 9421 9380-1030