The discovery of a catalyst that makes it possible to use sunlight to turn carbon dioxide into synthetic natural gas could make carbon neutral ‘fossil’ fuel a viable option.
Researchers at the University of Adelaide in South Australia, in collaboration with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), have developed a technique that combines CO2 with hydrogen to produce almost pure methane. Methane is considered a safer option than hydrogen as an energy source and allows the use of the existing natural gas infrastructure.
Similar research previously has discovered problems with candidate catalysts – poor CO2 conversion, unwanted carbon monoxide production, catalyst stability, low methane production rates and high reaction temperatures.
But using a catalyst synthesised with porous crystals called metal-organic frameworks researchers were able to minimise carbon monoxide production.
The lead author of the research report, which has been published online in the Journal of Materials Chemistry, is Renata Lippi, who commented that the process only required a small amount of the catalyst, which increased its economic viability.
“Natural gas is already in use but it is a fossil fuel and is one of the main fuels used in many industrial activities,” she said. “The problem with that is we are getting carbon stored underground but with this synthesis, organic CO2 in a gas form and reacting with hydrogen, we can make synthetic natural gas without adding carbon dioxide to the atmosphere. We would be recycling. We use a really high flow of gas and still we reach almost full conversion of the reagents.” The process proved to be highly stable even under high continuous reaction for several days and after shutdown and exposure to air. The catalyst also operated at mild temperatures and low pressures, making solar thermal energy possible.
Lippi said that therefore hydrogen could be efficiently produced with solar energy and combining it with CO2 to produce methane was a safer option than using hydrogen directly.
The next step is to improve methods for CO2 capture and developing a hydrogen electrolysis method so the whole process could be integrated into the same plant.
With the large global push for more renewable energy and the existing infrastructure for natural gas, there is huge potential for effective use of this new technique. “What we’ve produced is a highly active, highly selective (Producing almost pure methane without side products) and stable catalyst that will run on solar energy,” said project leader Christian Doonan.
“This makes carbon neutral fuel from CO2 a viable option.”