Researchers at Newcastle University have developed a new self-forming membrane to separate carbon dioxide (CO2) from a mixture of gases.

Acting much like a filter, the developed membrane lets harmless gases, such as nitrogen, exit into the atmosphere so that the CO2 can be processed.

The team believe the system may be applicable for use in CO2 separation processes, both to protect the environment and in reaction engineering.

By growing the expensive part of the membrane – made from silver – during membrane operation, the research reduced both the cost of the membrane and demand of silver.

“We didn’t build the entire membrane from silver, instead we added a small amount of silver and grew it within the membrane adding the functionality we desired,” explained Dr Greg Mutch, NUAcT Fellow from the School of Engineering at Newcastle University.

“Most importantly, the performance of the membrane is at the level required to be competitive with existing carbon capture processes – in fact, it would likely reduce the size of the equipment required significantly and potentially lower operating costs.”

In a method never tried before and described in the research paper, aluminium oxide supports in pellet and tubular form were used to grow the silver membrane.

Silver was added to the membrane, and the conditions experienced during operation forced the silver to grow within the membrane, resulting in higher performance.

Then by using X-ray micro-computed tomography, the team were able to look inside the membrane and confirm that the permeation of CO2 and oxygen stimulated self-assembly of silver dendrites.

“These savings are important – the cost of carbon capture is one of the key factors limiting uptake of the technology. There is a common metric for membrane performance – the “upper bound”

“As our membrane relies on a unique transport mechanism, we avoid the limitations of most membrane materials and go far beyond the upper bound.”