“This is the first MOF to both capture and convert a toxic, gaseous air pollutant into a useful industrial commodity.” said Dr Sihai Yang, a lead author and a senior lecturer at The University of Manchester’s Department of Chemistry. “It is also interesting that the highest rate of NO2 uptake by this MOF occurs at around 45 degrees Centigrade, which is about the temperature of automobile exhausts.”
Professor Martin Schröder, Vice-President and Dean of the Faculty of Science and Engineering at The University of Manchester, said: “The global market for nitric acid in 2016 was USD $2.5 billion, so there is a lot of potential for manufacturers of this MOF technology to recoup their costs and profit from the resulting nitric acid production. Especially since the only additives required are water and air.”
As part of the research, the scientists used neutron spectroscopy and computational techniques at ORNL to precisely characterize how MFM-520 captures nitrogen dioxide molecules.
“This project is an excellent example of using neutron science to study the structure and activity of molecules inside porous materials,” said Timmy Ramirez-Cuesta, co-author and coordinator for the chemistry and catalysis initiative at ORNL’s Neutron Sciences Directorate. “Thanks to the penetrating power of neutrons, we tracked how the nitrogen dioxide molecules arranged and moved inside the pores of the material, and studied the effects they had on the entire MOF structure.”
“The characterisation of the mechanism responsible for the high, rapid uptake of NO2 will inform future designs of improved materials to capture air pollutants.” said Jiangnan Li, the first author and a PhD student at The University of Manchester.
In the past, capturing greenhouse and toxic gases from the atmosphere was a challenge because of their relatively low concentrations and because water in the air competes and can often affect negatively the separation of targeted gas molecules from other gases. Another issue was finding a practical way to filter out and convert captured gases into useful, value-added products. The MFM-520 material offers solutions to many of these challenges.
The paper, ‘Capture of nitrogen dioxide and conversion to nitric acid in a porous metal-organic framework, by authors; Sihai Yang; Martin Schröder; Jiangnan Li; et al, is published in Nature Chemistry.
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