Chemists at the University of Bayreuth have developed a material that could well make an important contribution to climate protection and sustainable industrial production. With this material, the greenhouse gas carbon dioxide (CO₂) can be specifically separated from industrial waste gases, natural gas, or biogas, and thereby made available for recycling. The separation process is both energy efficient and cost-effective. In the journal Cell Reports Physical Science the researchers present the structure and function of the material.
The Green Deal presented by the European Commission in 2019 calls for the net emissions of greenhouse gases within the EU to be reduced to zero by 2050. This requires innovative processes that can separate and retain CO2from waste gases and other gas mixtures so that it is not released into the atmosphere. The material developed in Bayreuth has one fundamental advantage over previous separation processes: It is capable of completely removing CO2from gas mixtures without chemically binding CO2.
These gas mixtures can be waste gases from industrial plants, but also natural gas or biogas. In all these cases, CO2accumulates in the cavities of the material solely due to physical interaction. From there, it can be released without great expenditure of energy, to be made available again as a resource for industrial production. Hence, the separation process works, chemically speaking, according to the principle of physical adsorption. Like a spacious storage tank, the new material can be filled with and emptied of carbon dioxide in an energy-efficient way. In Bayreuth laboratories, it was designed in such a way as to only separate out CO2and no other gas from the most varied gas mixtures.
“Our research team has succeeded in designing a material that fulfils two tasks at the same time. On the one hand, the physical interactions with CO2are strong enough to free and retain this greenhouse gas from a gas mixture. On the other hand, however, they are weak enough to allow the release of CO2from the material with only a small amount of energy,” says Martin Rieß M.Sc., first author of the new publication and doctoral researcher at the Inorganic Chemistry I research group at the University of Bayreuth.
The new material is an inorganic-organic hybrid. The chemical basis is clay minerals consisting of hundreds of individual glass platelets. These are only one nanometre thick each, and arranged precisely one above the other. Between the individual glass plates there are organic molecules that act as spacers. Their shape and chemical properties have been selected so that the pore spaces created are optimally tailored to accumulate CO2. Only carbon dioxide molecules can penetrate into the pore system of the material and be retained there. In contrast, methane, nitrogen, and other exhaust gas