Captured carbon could convert to chemical feedstock

In the matter of carbon capture and storage – one of the three main strategies in play globally in the quest to limit global warming – the “storage” part of the equation is problematic.

In brute terms, the captured carbon, in the form of carbon-dioxide emissions, needs to be sequestered, which takes up a lot of space and costs a lot of money.

Now, however, researchers led by Sicong Tian from Australia’s Macquarie University have come up with a process that allows captured carbon to be converted into a useful feedstock for the global chemistry industry.

The process, described in a paper in the journal Science Advances, is particularly suited to large stationary carbon-emitters, such as coal-fired power stations.{%recommended 8759%}

The method, they report, is essentially a way of “closing the anthropogenic carbon cycle” that does away with the need for large-scale long-term storage. 

Tian and colleagues propose an approach called calcium-looping. Emitted carbon dioxide is captured on a calcium-oxide sorbent, to which a nickel catalyst is added. Methane is then also added, which in combination with the nickel works to separate the molecular bonds holding the carbon dioxide molecules together, making them separate into carbon monoxide.

This is then combined with hydrogen to form what is known as synthesis gas, or syngas, a platform mixture that is in great demand in the chemical industry as a precursor to the production of hydrogen, ammonia, methanol, and synthetic hydrocarbon fuels. At half the density of natural gas, syngas can also be used in electricity generation.

Currently, converting captured carbon dioxide into other substances is an expensive and tricky business. At present, just 0.3% of global carbon dioxide emissions are converted, overwhelmingly for the making of urea.

The new proposed approach, note the researchers, is both eminently scalable and considerably more cost efficient than other reuse scenarios being investigated. In large part, they say, this is because there will never be a shortage of the key added ingredient, methane.

“Therefore, a CO2 conversion reaction with a reducing agent that is earth abundant and readily available would be of great worth for future technical exploration and development, considering the decarbonisation targets of large CO2 stationary sources worldwide,” they conclude.

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