"In order for industrial production (...) to remain possible, we have to break completely new technological ground," says Dr. Benjamin Dietrich from the Institute of Thermal Process Engineering (TVT) at KIT. "This also applies to the provision of carbon in industry. This is needed in the production of batteries, in the paint industry, in the agricultural sector and also in the manufacture of building materials. So far, it has mostly come from fossil sources."
In the NECOC (NEgative CarbOn dioxide to Carbon) research project, which Dietrich is coordinating, the joint partners KIT, Ineratec and Climeworks are developing a process that can be used to convertCO2 from the atmosphere into carbon. "If this then remains bound in the long term, we combine negative emissions with a component of the post-fossil raw material supply in the sense of a future carbon management strategy. This is a double contribution to a more sustainable future," says Dietrich. In the first phase of the project, the research team set up a container-scale pilot plant, which has now gone into operation. In continuous operation, this first expansion stage removes almost two kilograms ofCO2 from the ambient air every day and produces 0.5 kilograms of solid carbon from it.
The NECOC process combines three process steps: In the first step, an adsorber is used to separate theCO2 from the ambient air (direct air capture). In the second step, it is reacted in a micro-structured reactor with renewably produced hydrogen from a connected electrolyzer. The carbon and oxygen components form new bonds, and theCO2 is now turned into methane and water. The water flows back into the electrolyser, the methane with its carbon component flows further into a reactor with liquid tin.
In the third process step, a pyrolysis reaction takes place in rising bubbles and the methane molecules are broken down. This produces H2, which is used again to separateCO2 in the process. What remains is carbon, which floats on the tin as a micro-granular powder and is continuously separated mechanically. By changing process parameters such as the temperature level, carbon modifications such as graphite, carbon black or even graphene can be produced.
