Useful industrial products like plastics and fuels can be made by using harmful carbon dioxide emissions. University of New South Wales, Sydney, chemical engineers developed a new technology to convert the CO2 into the chemical building blocks employed to make such products. The team is now working on validating the technology in an industrial setting. If everything works out, the process can be adopted on a large scale and thus give the world breathing space in its transitions towards a green economy.
Dr. Rahman Daiyan and Dr. Emma Lovell carried out the research in the Particles and Catalysis Research Laboratory led by Scientia Professor Rose Amal. Together, they created nanoparticles by making zinc oxide at extreme temperatures using a technique called flame spray pyrolysis. The nanoparticles are what promote the conversion of CO2 into useful industrial components. They act as a catalyst for turning the greenhouse gas into syngas, which is a mix of carbon monoxide and hydrogen. It is used in the manufacture of industrial products.
Dr. Lovell said:
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. 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.
The method is more scalable to the requirements of heavy industry and cheaper than what is currently available.
Closing The Carbon Loop
Dr. Daiyan explains how an electrolyzer containing the FSP-produced zinc oxide nanoparticles could be retrofitted to an industrial setting to make use of waste carbon emissions:
Waste CO2 from say, a power plant or cement factory, can be passed through this electrolyzer, 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.
Dr. Lovell added:
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 the industry.
The most exciting part of this technology is that by making small adjustments to the way the nanoparticles are burned, it determines the final mix of the syngas building blocks produced.
Dr. Daiyan said:
At the moment you generate syngas by using natural gas—so from fossil fuels. 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 then elaborates on why the use of zinc oxide as a catalyst is a cheaper alternative:
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. 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.
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.
For now, the team has just tested this technology on a small scale. They know that an electrolyzer can turn waste CO2 gas that contains contaminants into syngas of different kinds. However, they still don’t know if it works on a large-scale – if it could convert all of the waste CO2 emitted by a power plant. So, next, the researchers will test the nanomaterial in a flue gas setting to see if they’re tolerant of the conditions found in industrial waste gas.
