Material could enable cheaper method of carbon capture

A cheaper method of carbon capture could emerge from the creation of a unique porous material by UK researchers.

A team of scientists from Nottingham and Newcastle universities has designed a honeycomb-like metal organic framework (MOF) known as NOTT-202a to adsorb and release carbon dioxide (CO2) gas at lower temperatures than existing capture methods.

The material adsorbs CO2 under pressure and releases it as the pressure is decreased, while allowing other chemicals such as hydrogen, nitrogen and methane to pass out of it first.

NOTT-202a could avoid the need for the amine solutions that are commonly used in carbon capture but must be heated to release the CO2 and can also be toxic.

‘The most novel aspect of this paper is the structure of the material itself,’ said Prof Marin Schröder, head of inorganic chemistry at Nottingham and one of the authors of a paper on the research published in Nature Materials.

The material consists of two interpenetrating networks formed from organic ligand molecules attached to a central indium metal atom, but with holes or defects in one of the networks to create more space in which to hold CO2.

‘So you have a more porous network than what you would normally expect while the interpenetration means you have greater interactions between the pore walls and therefore you get stronger interactions with gases,’ said Schröder.

‘It’s a contradiction. You need narrow pores to maximise the interaction with gases but you also want the pores to be bigger so each can hold more gas.’

The researchers used the Diamond Light Source synchrotron at the Science and Technology Facilities Council’s Rutherford Apple Laboratory to take X-ray powder diffraction measurements that allowed them to see inside the material’s structure.

They have also developed a computer simulation that will allow them to test new designs of the material as they go through the process of optimising it so it can be scaled up for use in real carbon capture systems.

‘There are all manner of issues about scale-up of this material,’ said Schröder. ‘Can we make this material cheaply? Can we develop the ligand synthesis to be more green?’