To limit climate change, most governments focus on reducing the amount of carbon dioxide (CO₂) put into the atmosphere. But there are indications that such action won’t be enough—at some point, we will need to actively remove CO₂ from the air.

The removal of CO₂ is a big challenge, as it will require large amounts of renewable energy. For now, attention has focused on removing CO₂ from the exhaust of fossil fuel power plants, where it’s present in higher concentrations. Typically, that CO₂ is destined for carbon capture and storage (CCS), but another option is to skip the storage part—new research from Korea shows that it’s possible to take CO₂ directly from exhaust gases and make new chemicals.

Catch me if you can

CO₂ from an exhaust gas stream is often captured by nitrogen-containing compounds called amines. The reaction is reversible, as the products can be heated, allowing the CO₂ to be released. The gas can then be compressed, transported, and stored in geological features, such as depleted oil fields, or used as raw material in chemical factories.

Although trees and some microbes can capture CO₂ and incorporate it into more complex chemicals, humans have struggled to replicate the process on a large scale. Most chemical reactions involving CO₂ require expensive catalysts, high temperatures, or high pressures to make it react. The most common use of CO₂ as a chemical feedstock is in the formation of urea, which is found in around 90 percent of the world’s fertilisers.

In the new research, published in the journal Angewandte Chemie, Soon Hong and colleagues from the Institute for Basic Science in South Korea have caught CO₂ from exhaust gas and incorporated it into useful chemicals. One product is called alkynyl carboxylic acid, which has many uses, including making food additives. Another, cyclic carbonate, is used to make polymers for cars and electronics. Cyclic carbonates can also be used in place of phosgene, a very reactive and highly toxic chemical that is a starting material for a wide variety of useful products.

Hong compared these reactions to ones performed using highly pure CO₂, which is sold at a high price and requires lots of energy to make, in the same chemical reactions, but there was hardly any difference in the final yield.

As in CCS technologies, Hong passes exhaust fumes through a solution of amines, where CO₂ is captured and other gases pass unhindered. The resulting salt is then heated to yield pure CO₂ for chemical reactions. Hong can recycle the amine solution at least 55 times without a loss in yield.

Use me if you do

In another research paper just published in Nature Communications, Matthias Beller and colleagues at the University of Rostock in Germany show a new reaction that can use CO₂. Called alkene carbonylation, it usually requires the use of carbon monoxide (CO), which, as home detectors know well, is a highly toxic gas.

CO₂ has previously been used in the synthesis of carboxylic acids by using diethylzinc to drive the reaction. But diethylzinc is flammable in air. With the new reaction, Beller can make chemicals that are found in varnishes and paints with less risk of burning the lab down.

The researchers carried out a number of reactions and confirmed that the source of the newly formed C-O bonds was CO₂. This work shows that CO₂ can be used as a viable alternative to carbon monoxide in carbonylation reactions, which could increase the importance of CO₂ in the chemical industry.

While this is good news, energy is still needed to trap and use CO₂. But if researchers can increase the demand for CO₂ at industrial scale, they may also drive the development of some of the technologies needed for CCS.

Nature Communications, 2014. DOI: 10.1038/ncomms4091 and Angewandte Chemie, 2014. DOI: 10.1002/anie.201308341 (About DOIs).

Jessica Breen is a postdoctoral researcher at the University of Leeds. This article was originally published on The Conversation.