“We used an open flame, which burns at 2000 degrees, to create nanoparticles of zinc oxide that can then be used to convert CO2, using electricity, into syngas,” says Dr. Lovell.
“Syngas is often considered the chemical equivalent of Lego because the two building blocks—hydrogen and carbon monoxide—can be used in different ratios to make things like synthetic diesel, methanol, alcohol or plastics, which are very important industrial precursors.
“So essentially what we’re doing is converting CO2 into these precursors that can be used to make all these vital industrial chemicals.”
Closing the loop
In an industrial setting, an electrolyser containing the FSP-produced zinc oxide particles could be used to convert the waste CO2 into useful permutations of syngas, says Dr. Daiyan.
“Waste CO2 from say, a power plant or cement factory, can be passed through this electrolyser, and inside we have our flame-sprayed zinc oxide material in the form of an electrode. When we pass the waste CO2 in, it is processed using electricity and is released from an outlet as syngas in a mix of CO and hydrogen,” he says.
The researchers say in effect, they are closing the carbon loop in industrial processes that create harmful greenhouse gases. And by making small adjustments to the way the nanoparticles are burned by the FSP technique, they can determine the eventual mix of the syngas building blocks produced by the carbon dioxide conversion.
“At the moment you generate syngas by using natural gas—so from fossil fuels,” Dr. Daiyan says. “But we’re using waste carbon dioxide and then converting it to syngas in a ratio depending on which industry you want to use it in.”
For example, a one to one ratio between the carbon monoxide and hydrogen lends itself to syngas that can be used as fuel. But a ratio of four parts carbon monoxide and one part hydrogen is suitable for the creation of plastics, Dr. Daiyan says.
Cheap and accessible
In choosing zinc oxide as their catalyst, the researchers have ensured that their solution has remained a cheaper alternative to what has been previously attempted in this space.
“Past attempts have used expensive materials such as palladium, but this is the first instance where a very cheap and abundant material, mined locally in Australia, has been successfully applied to the problem of waste carbon dioxide conversion,” Dr. Daiyan says.
Dr. Lovell adds that what also makes this method appealing is using the FSP flame system to create and control these valuable materials.
“It means it can be used industrially, it can be scaled, it’s super quick to make the materials and very effective,” she says.
“We don’t need to worry about complicated synthesis techniques that use really expensive metals and precursors—we can burn it and in 10 minutes have these particles ready to go. And by controlling how we burn it, we can control those ratios of desired syngas building blocks.”
While the duo have already built an electrolyser that has been tested with waste CO2 gas that contains contaminants, scaling the technology up to the point where it could convert all of the waste carbon dioxide emitted by a power plant is still a way down the track.
“The idea is that we can take a point source of CO2, such as a coal fired power plant, a gas power plant, or even a natural gas mine where you liberate a huge amount of pure CO2 and we can essentially retrofit this technology at the back end of these plants. Then you could capture that produced CO2 and convert it into something that is hugely valuable to industry,” says Dr. Lovell.
The group’s next project will be to test their nanomaterials in a flue gas setting to ensure they are tolerant to the harsh conditions and other chemicals found in industrial waste gas.
Rahman Daiyan et al, Uncovering Atomic‐Scale Stability and Reactivity in Engineered Zinc Oxide Electrocatalysts for Controllable Syngas Production, Advanced Energy Materials (2020). DOI: 10.1002/aenm.202001381
Engineers find neat way to turn waste carbon dioxide into useful material (2020, June 10)
retrieved 11 June 2020
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.