The cement industry accounts for between four to eight percent of all global CO2 emissions. But what if the carbon dioxide that’s released in the process of burning calcium carbonate could be captured and put to good use? A new Power-to-chemicals project called CO2-Syn will explore this possibility; as well as decarbonising the industry, it aims to develop marketable CO2-based products.

The concept works like this: firstly, green electricity (produced from renewables) is used to convert CO2 and water into carbon monoxide and hydrogen (H2) via electrolysis; then, mixtures of these gases are used in a series of catalytic reactions to produce basic chemical products including olefins and higher alcohols.

One of the biggest challenges faced by the lead team at the Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT) is how to purify the toxins and dust in the CO2 emissions in a cost-effective manner. "Ideally, we want to use the CO2 waste gas flows directly to produce the synthesis gases with the help of renewable energies and waste heat sources – without any complex upstream purification and conditioning," says Dr Anne Schmidt from Leuchtstoffwerk Breitungen GmbH, the project’s chemicals partner, in a press release from the Fraunhofer UMSICHT. "For this, we need robust and poisoning-resistant catalysts that are both stable over the long term and economical."

The researchers focus on sulphide-, nitride- and phosphide-based materials. Once the chemical solution has been tested in a real plant at Phoenix Cement Works, they must then work out how to integrate it into the whole production process for roll-out in other plants.

Finally, new business models for the end-products must be developed with input from the Ruhr University Bochum. The olefin ethylene, for example, is used in the production of plastics such as polyethylene or polystyrene, while the higher alcohols are used as solvents and thinners, in paints and as fuel additives.