Researchers have discovered a metal carbide nanoparticle (a compound of carbon and metal) that can convert CO2 into fuel; a particle that for the first time, can be produced sustainably at low temperatures.
This means that the particles can be produced at an industrial scale at a low cost, and with minimal environmental impact, providing a vital pathway toward reducing the world's greenhouse emissions, according to the study, published in the journal American Chemical Society.
The aim of the project was to capture carbon emissions from an emission source, such as a flue, and then to convert it into usable fuels, with the nanoparticles functioning as a catalyst to enable the reaction, the researchers said.
Turning carbon dioxide back into hydrocarbons
"Basically what we're doing is we're turning the carbon dioxide from carbon-oxygen bonds to carbon-hydrogen bonds. So, we're turning carbon dioxide back into hydrocarbons," said study researcher Noah Malmstadt, Professor at the University of Southern California in the US.
"Hydrocarbons are basic fuel stock. You can either turn them into fuel stock chemicals such as methane or propane. Or you can use them as the basis for chemical synthesis so they can be building blocks for making more complex chemicals," Malmstadt said.
He said that hydrocarbons were also "feedstock" chemicals that could potentially be used to create other carbon-based material, so carbon emissions could be converted into the material to make consumer products as well as a hydrocarbon fuel.
According to the researchers, until now, the process for creating the catalyst particles has been very energy-intensive, making it an impractical solution for converting carbon emissions.
The carbides are created using a process where they are heated to temperatures higher than 600 degrees centigrade, a process that makes it difficult to control the size of the particles, which impacts on their effectiveness as catalysts.
Malmstadt said that in contrast, the team's discovery uses a millifluidic reactor process, a very small- scale chemical reactor system, which has a minimal environmental footprint.
This means the particles can be produced at temperatures as low as 300 degrees centigrade, resulting in smaller, more uniform particles, which make them ideal for converting CO2 to hydrocarbons.
"We are producing the particles sustainably, using green chemistry methods," he said.
"The chemical reactor system operates in channels that are less than a millimetre across, which offers a ton of advantages over traditional reactors, particularly in terms of making materials that are very uniform and very high quality," he added.
Malmstadt said that the resulting nanoparticles have a very high surface area to mass ratio.
"So for each amount of metal that you have in the catalyst, you get a more active surface area that can do chemistry," he said.
The researchers said that this process also offered significant cost savings over larger-scale chemical reactor production of carbide nanoparticles.