CO₂ as a new source of carbon

From climate offender to useful material

More than 30 billion tons of CO₂ are released into the atmosphere every year. But this greenhouse gas need no longer be just a climate-damaging waste product. Researchers headed by Bayer have found a way to use carbon dioxide as a building block for premium plastics.

pilot plant
Bayer employee Deniz Capar in a pilot plant in Leverkusen. A chemical precursor for plastics is produced here with the help of CO₂.

Christoph Gürtler carefully pours out a thick, crystal-clear liquid and tips a yellow chemical into it. Then he adds just a little water to the beaker, a couple drops of accelerant and gives it all a good stir. After a few seconds, a green mass rises to the top. It overflows slightly, then hardens: The experiment is a success!

“This is a common foam,” Gürtler says. “We’ve now made ground-breaking progress with the help of a new ingredient,” says the Bayer researcher, holding up the glass containing the clear substance. “There is an entirely new raw material in here: carbon dioxide.”

Until now, polyurethane foam of this kind – like most things in the chemical industry – has been manufactured differently, namely using fossil resources: petroleum, natural gas, coal, biomass. These four substances are the starting point for some 40 basic chemicals and more than 40,000 chemical products. But they have disadvantages: Supplies are limited, they are getting increasingly expensive and they consume a lot of energy when treated in refineries.

Substitute for petroleum

But CO₂is another story. It is virtually ubiquitous and available in unlimited quantities. Like oil, it incorporates the important element carbon, on which the entire field of chemistry depends. In other words, this climate-killer has what it takes to be useful, and Bayer MaterialScience is working on a number of projects with partners in industry and academia.

The Dream Production research initiative has made the most progress. It is the proof that incorporating CO₂ is not only possible in the lab, but also on an industrial scale. The carbon dioxide comes from a power plant near Cologne, Germany, operated by energy company RWE. There it is removed from the flue gas and liquefied for transportation.

In a pilot plant in nearby Leverkusen, Bayer MaterialScience has been using the carbon dioxide since early 2011 to manufacture samples of the polyurethane component polyol. The test foams made from this substance are just as good as those produced the conventional way using only petroleum.

“This new process was made possible by a scientific breakthrough,” explains project manager Christoph Gürtler. “We finally succeeded in finding the right catalyst after the scientific community spent decades searching for it.” A catalyst is required to set the reaction in motion. In other words, the CO₂ has to be given a nudge, because it is chemically inert and does not react readily on its own with other substances.

Sustainable process

The catalyst also limits the energy consumed by the reaction. As a result, the entire process is ecologically sustainable, as demonstrated by a complex study conducted by RWTH Aachen University, another partner on the project. “Our calculations indicate that the new process requires less energy in its life cycle and thus also emits less CO₂,” explains Professor André Bardow of the Institute of Technical Thermodynamics.

If the new process continues to produce good results, Bayer intends to start industrial production in 2015. The first end product to be launched on the market will be mattresses made from CO₂-based flexible foam. Subsequently, other types of polyurethane are also to be manufactured by this method.

“Large segments of the industry are already showing significant interest in the innovative material,” says Frank Grunert, head of Polyurethane Marketing at Bayer MaterialScience. Bayer is now looking for partners along the value-added chain to the consumer as the project moves to market maturity.

And research continues as well, for instance in another project called CO₂RRECT that reaches far into the future. It focuses on combining carbon dioxide and renewable energies, or more specifically excess electricity from wind turbines, for which storage capacities are insufficient. The energy can, however, be stored chemically in the form of hydrogen. An electrolysis process, run on this excess energy, produces the hydrogen.

Wind power and carbon dioxide

But the project partners headed by Bayer MaterialScience envision much more: They want to combine hydrogen with power plant CO₂ to obtain chemical intermediates, which could be used in turn to produce polyurethane or the performance plastic polycarbonate.

“Our ultimate goal is to manufacture a broad range of plastics from CO₂, including not only coatings and fibers,” says Gürtler, “but also plastics made entirely of alternative raw materials. The first products containing no petroleum at all – that’s our vision.”

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