CO2 conversion process offers new route to CCS

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Researchers have developed a method of capturing carbon dioxide and converting it to solid carbon, an advance that could help to decarbonise heavy industries.

The carbon dioxide utilisation technology from RMIT researchers in Australia is designed to be integrated into existing industrial processes for heavy industries like cement and steel, which are energy-intensive and emit CO2 as part of the production process.

The new technology is claimed to offer a route for instantly converting carbon dioxide as it is produced and locking it permanently in a solid state, keeping CO2 out of the atmosphere. The research is published in Energy & Environmental Science.

Co-lead researcher Associate Professor Torben Daeneke said the work built on an earlier experimental approach that used liquid metals as a catalyst.

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“Our new method still harnesses the power of liquid metals but the design has been modified for smoother integration into standard industrial processes,” Daeneke said in a statement. “As well as being simpler to scale up, the new tech is radically more efficient and can break down CO2 to carbon in an instant.”

A provisional patent application has been filed for the technology and the researchers have signed a $AUD2.6m agreement with Australian environmental technology company ABR, who are commercialising technologies to decarbonise the cement and steel industries.

Technologies for carbon capture and storage (CCS) have largely focused on compressing CO2 into a liquid and injecting it underground. The Australian Government has highlighted CCS as a priority technology for investment in its net zero plan, announcing a $1bn fund for the development of new low emissions technologies.

PhD researcher Karma Zuraiqi with liquid metal at the heart of the new carbon dioxide utilisation technology (Image: RMIT)

Daeneke, an Australian Research Council DECRA Fellow, said the new approach offered a sustainable alternative, with the aim of preventing CO2 emissions and delivering value-added reuse of carbon.

The RMIT team, with lead author and PhD researcher Karma Zuraiqi, employed thermal chemistry methods used by industry to develop their CCS technology.

The so-called bubble column method starts with liquid metal - eutectic gallium-indium (EGaIn) - being heated to about 100-120°C. Carbon dioxide is injected into the liquid metal and as the rising bubbles move through the liquid metal the gas molecule splits up to form flakes of solid carbon, with the reaction taking a split second.

“It’s the extraordinary speed of the chemical reaction we have achieved that makes our technology commercially viable, where so many alternative approaches have struggled,” said co-lead researcher Dr Ken Chiang.

The next stage in the research is scaling up the proof-of-concept to a modularised prototype the size of a shipping container, in collaboration with ABR.