What could be more cost effective than a technology that builds itself? A group of researchers at Newcastle University have developed a new class of self-forming membrane that separates carbon dioxide from a mixture of gases.
Operating like a coffee filter, it lets harmless gases, such as nitrogen, exit into the atmosphere and then the carbon dioxide can be processed.
The team believe that the system may be applicable for use in carbon dioxide separation processes, either to protect the environment at a flue gas site or in reaction engineering.
By growing the expensive part of the membrane – made from silver – during membrane operation, they dramatically reduced the demand for silver and the cost of the membrane.
The work is published in Energy and Environmental Science and Dr Greg Mutch, NUAcT Fellow from the School of Engineering, Newcastle University, UK explains, “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.
“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.”
The self-forming membrane
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, bestowing higher performance.
Using X-ray micro-computed tomography, the team were able to look inside the membrane and confirm that the permeation of CO2 and O2 stimulated self-assembly of silver dendrites.
Importantly, the performance of the membrane was shown through permeation measurements to be at the level required to be competitive with existing carbon capture processes. The permeability of the membrane was one order of magnitude higher than that required, and the flux of CO2 was the highest reported for this class of membrane.
Dr Mutch added: “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!
“We hope that this study inspires new ways to form membranes, that lower costs, as well as drives interest in this new class of membrane for future application to protect our environment.”