Facility to convert CO2 to carbon black powder

As part of the NECOC research project, currently underway at Germany’s Karlsruhe Institute of Technology (KIT), a test facility is being built for active reduction of atmospheric carbon dioxide (CO₂).

The container-scale facility seeks to convert CO₂ contained in ambient air into highly pure carbon black powder that can be used as a resource in industry. It will be built on the premises of KIT, which as project coordinator will operate the facility as well as contribute its pyrolysis technology.

In order to successfully limit global warming to below 2°C by the end of the century, efforts to reduce greenhouse gas emissions will have to be complemented by solutions for removing already emitted CO₂ from the atmosphere. As explained by KIT Professor Thomas Wetzel, “Our project approach consists of removing CO₂ from the atmosphere and converting it into carbon black, ie, highly pure carbon in powder form.

“In this way, a hazardous greenhouse gas will be converted into a raw material for high-tech applications. Carbon black can be used in electronics, printing or construction.”

The NECOC test facility will first deploy an adsorber to capture CO₂ from ambient air (direct air capture, or DAC). Together with renewable hydrogen, it is then converted into methane and water in a microstructured reactor. The methane produced serves as a carbon carrier in the downstream process and is passed into a bubble reactor filled with liquid tin. In the ascending methane bubbles, a pyrolysis reaction takes place, by means of which methane is decomposed into its constituents. These are hydrogen, which is directly fed back to methanation, and solid carbon in the form of microgranular powder, ie, carbon black.

All process steps have already been studied and developed up to the laboratory scale by the researchers involved. As noted by NECOC Project Coordinator Dr Benjamin Dietrich, “We know the individual modules well; however, they have never been realised together in an integrated facility so far. This is the first time worldwide. Skilful integration of the process modules and correct process conduct will be decisive for the energy efficiency of the process and the quality of the carbon black product.”

The major advantage over previously proposed concepts to reduce atmospheric CO₂, such as carbon capture and storage methods (CCS) to store CO₂ in deep rock layers, is in the end product. Dr Dietrich said, “Solid carbon is far less difficult to handle than CO₂ and can even be used as a resource. So far, carbon black has been produced mainly from fossil petroleum. That is why our process represents a technological approach for a sustainable future in several respects. It combines the direct contribution to solving the climate problem with a process for post-fossil resource supply.”

The three-year research project has received €1.5 million in funding from the Federal Ministry for Economic Affairs and Energy (BMWi), with project partners including KIT spinoff INERATEC and ETH Zurich spinoff Climeworks. Future extensions of the facility are planned to increase the performance per container and to enable parallel operation of many facilities.

Image caption: An integrated pilot plant is being built to test a new process for reducing the greenhouse gas CO₂ in the atmosphere. The process will produce carbon black — a high-quality, solid carbon. Image credit: Moritz Leg.

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