The group developed a metal-organic framework (MOF), MFM-170, that can selectively take in toxic sulfur dioxide gas at record concentrations and preserve it for use in chemical production. By doing state-of-the-art structural, dynamic and modelling studies at National Facilities such as ISIS and Diamond Light Source to conduct neutron and X-ray scattering experiments, and the Advanced Light Source in Berkeley USA to conduct single crystal diffraction work, they have been able to determine the precise host-guest binding of the sulfur dioxide within MFM-170 at a molecular level.
Toxic sulfur dioxide (SO2) emissions have severe effects on human health and the environment, even in trace amounts. State-of-the-art technologies to remove SO2 from pollution sources heavily rely on the use of limestone, remove just 60-95% and generate huge amounts of waste solids and water, resulting in significant environmental impacts. Research into new technologies for reversible SO2 capture is urgent but is challenging due to the highly corrosive nature of SO2.
The study, led by Dr Gemma Smith from the University of Manchester, has recently developed a new porous material, MFM-170, which shows an adsorption of SO2 higher than any other porous material known to date. This work is unprecedented as, unlike many other metal-organic frameworks, MFM-170 is remarkably stable to SO2 exposure, even in the presence of water, and the adsorption is fully reversible at room temperature.
Her recent paper, published in Nature Materials, also describes the scale up of MFM-170 and its successful implementation for dynamic separation of SO2 from gas mixtures that replicate those found in industry. Using inelastic neutron scattering on TOSCA at ISIS, Infrared and X-ray diffraction experiments on B22 and I11 at Diamond, and other facilities in the USA, her and the rest of the research group were able to do comprehensive studies in operando, observing the adsorption of SO2 in real time.
“Our material has been shown to be extremely stable to corrosive sulphur dioxide and can effectively separate it from humid waste gas streams. Importantly, the regeneration step is very energy-efficient compared to those reported in other studies; the captured sulphur dioxide can be released at room temperature for conversion to useful products, whilst the metal-organic framework can be reused for many more separation cycles."
Dr Smith explains; “Neutrons are very sensitive to lighter elements and the high spectral resolution of TOSCA allowed us to successfully answer challenging questions on how trapped water and sulphur dioxide molecules interact with each other and the material, MFM-170."
The full paper can be found at DOI: 10.1038/s41563-019-0495-0
Read our other science highlights from TOSCA.