Imagine if you could not only permanently reduce carbon dioxide emissions, but also make economic use of the carbon and oxygen contained within them. Does that sound unrealistic to you? It doesn’t to thyssenkrupp. The company has joined forces with 16 other partners from the fields of industry and science, such as Siemens, Evonik, Linde, and the Fraunhofer Institute, to launch a large-scale research project: Carbon2Chem® converts metallurgical gases released during the steel production process into basic chemical components, which not only supports the economy, but can also improve the environmental impact of the steel industry.
Research under real conditions
To conduct the accompanying reality check, the thyssenkrupp Steel production location in Duisburg built a technology center. It is directly connected to the metallurgical gas pipelines of the integrated steel mill. Researchers inside the center have been combining basic scientific research with industrial expertise since April 2018. The first products are expected to arrive in September. Purifying metallurgical gases lies as the heart of Carbon2Chem®. This task is carried out by Linde AG, one of the world’s leading firms in the field of plant engineering, as well as the plant specialists at thyssenkrupp Industrial Solutions.
Converting metallurgical gases into chemical products
Normally, the majority of the metallurgical gases from the steel plant, coking plant, and blast furnace are burned to generate energy, then released into the atmosphere, with increased impact on the environment. Carbon2Chem® converts these gases into chemical products. The carbon dioxide contained in the gases in particular is used as a crude material.
The basic chemicals that are created are then further processed. The technology center will start by producing methanol and ammonia. Methanol is contained in some cleaning products and can also be used as a fuel. Ammonia is further processed into substances such as urea, which is processed in turn in the production of mineral fertilizer.
Reduced dependency on petroleum
Carbon2Chem® could contribute to reducing dependency on petroleum. We reuse the carbon that we inject into the blast furnace several times. This uses up fewer scarce fuel resources. Also, the chemical products that we produce are far more environmentally friendly than the ones made in the past. Scientist Dr. Wiebke Lüke, Carbon2Chem® Project Leader at thyssenkrupp AG, says: “For example, we can also manufacture oxymethylene ether. This is a diesel substitute that burns with less soot than conventional diesel does. However, switching to CO2 only makes sense if the lifecycle analysis shows that this option is less expensive on the whole. That factor always needs to be taken into account.”
A complicated process
Gas scrubbing represents a true challenge for the research project. “This lies at the heart of the Carbon2Chem® initiative,” says Dr. Andreas Frey, a development and process engineer at Linde. The metallurgical gases contain not only the hydrogen (H2), nitrogen (NH2), carbon monoxide (CO), and CO2 that we need for our chemical synthesis, but also a large amount of other components that damage highly sensitive catalyzers. Moreover, there are three different types of metallurgical gases: converter, blast furnace, and coke oven gas. “If we don’t manage to purify metallurgical gases to such an extent that we get a pure synthesis gas at the end of the process, then the concept behind Carbon2Chem® will have failed.”
The least available substance: hydrogen
In order to make use of the accrued carbon dioxide at the steel mill, more hydrogen than is required then can be extracted from metallurgical gases. There’s a solution for this, too. Lüke explains: “That’s why we generate additional H2 using the water electrolysis process developed by the thyssenkrupp Uhde Chlorine Engineers. This involves splitting water into hydrogen and oxygen using electricity. We use renewable energies to carry out water electrolysis.”
Seeing carbon dioxide in a new light
If the Carbon2Chem® project succeeds, it could change the image of carbon dioxide: CO2 will no longer be seen as harmful carbon emissions, which contribute to global warming and climate change, but rather, as a raw material. Moreover, Carbon2Chem® has the potential to become a key technology for global climate protection. It can be used in steel production as well as in other emissions-intensive branches of industry, not just those handling metals, thus reducing air pollution in those regions.