New catalyst converts CO2 to natural gas

Australian scientists have developed a new efficient catalyst that converts carbon dioxide (CO₂) from the air into synthetic natural gas, in what is claimed to be a clean process using solar energy. Invented at the University of Adelaide in collaboration with CSIRO, the process has the potential to replace fossil fuels while continuing the use of existing carbon-based fuel technologies without increasing atmospheric CO₂.

“Capturing carbon from the air and utilising it for industrial processes is one strategy for controlling CO₂ emissions and reducing the need for fossil fuels,” said University of Adelaide PhD candidate Renata Lippi, first author of the research published in the Journal of Materials Chemistry A.

“But for this to be economically viable, we need an energy-efficient process that utilises CO₂ as a carbon source.

“Research has shown that the hydrogen can be produced efficiently with solar energy. But combining the hydrogen with CO₂ to produce methane is a safer option than using hydrogen directly as an energy source and allows the use of existing natural gas infrastructure.

“The main sticking point, however, is the catalyst — a compound needed to drive the reaction because CO₂ is usually a very inert or unreactive chemical.”

The researchers created this catalyst using porous crystals called metal-organic frameworks which allow precise spatial control of the chemical elements. As noted by Dr Danielle Kennedy, AIM future science platform director with CSIRO, “The catalyst discovery process involved the synthesis and screening of more than 100 materials.”

Other catalysts have suffered from issues around poor CO₂ conversion, unwanted carbon-monoxide production, catalyst stability, low methane production rates and high reaction temperatures. The new catalyst efficiently produces almost pure methane from CO₂, with minimal carbon-monoxide production and high stability under both continuous reaction for several days and after shutdown and exposure to air.

Importantly, only a small amount of the catalyst is needed for high production of methane, which increases economic viability. The catalyst also operates at mild temperatures and low pressures, making solar thermal energy possible.

“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 Professor Christian Doonan, director of the University of Adelaide’s Centre for Advanced Nanomaterials. “This makes carbon-neutral fuel from CO₂ a viable option.”