Developing new technologies that can capture carbon dioxide from power plant emissions and convert it into useful products is a huge area of research with all kinds of potential (there’s even a US$20-million XPrize dedicated to such endeavors). Scientists in Australia are now claiming to have developed a new technique that converts CO2 into simple chemical building blocks that they liken to Lego, which can then be turned into products such as synthetic fuels and plastics.
The work was carried out in the School Of Chemical Engineering at the University of New South Wales, with the team setting out to use CO2 as a greener way of producing syngas. Typically made through the use of natural gas, syngas is chemically versatile and can be used to make a range of fuels and materials. By using waste carbon dioxide as a starting point, the scientists hoped to come up with a cheaper and scalable means of production, while reducing emissions at the same time.
The breakthrough starts with zinc oxide nanoparticles, which act as a catalyst for an efficient new chemical reaction. These are created by exposing zinc oxide to an open flame burning at 2,000 °C (3,632 °F) in a technique called flame spray pyrolysis. When carbon dioxide was mixed with the resulting zinc oxide nanoparticles inside an electrolyzer, the team found they could reduce the greenhouse gas to a mix of hydrogen and carbon monoxide known as syngas, or synthesis gas.
"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," says Dr Lovell. "So essentially what we’re doing is converting CO2 into these precursors that can be used to make all these vital industrial chemicals.”
According to the researchers, the particle-burning process could be tweaked to produce different mixes of syngas building blocks, depending on the desired final product. A ratio of one-to-one carbon monoxide to hydrogen, for example, would be highly suitable for fuel, while a four-to-one ratio would be better for the production of plastics.
What’s so promising about the technique in the eyes of the team is the effectiveness of the flame system in reducing the carbon dioxide to the syngas building blocks, which can be achieved in all of 10 minutes. The researchers say there is a way to go before the technique is scaled up to tackle the emissions from power plants, but they are very optimistic about the possibilities.
“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," says Dr Lovell. "Then you could capture that produced CO2 and convert it into something that is hugely valuable to industry."
The research was published in the journal Advanced Energy Materials.
Source: University of New South Wales
