Engineering news
The two families of stable metal-organic framework (MOF) materials, named UiO-66 and MFM-300, were developed by researchers at the University of Manchester to capture benzene.
The volatile organic compound (VOC) is an important feedstock for the production of many chemicals, including cyclohexane, which is used in nylon production. It also poses a serious health threat to humans when it escapes into the air, however.
VOCs such as benzene are common indoor air pollutants, linked with millions of premature deaths each year. Benzene is one of the most toxic VOCs, and is classified by the World Health Organization as a group one carcinogen to humans.
The new MOFs were designed and prepared to tackle that problem. The highly porous materials are made from metal nodes bridged by organic molecules that act as ‘struts’, forming three-dimensional lattices with empty channels that VOCs can enter.
The researchers demonstrated high adsorption of benzene at low pressures and concentrations, as well as the efficient separation of benzene and cyclohexane.
“The really exciting thing about these materials is that they allow us not only to capture and remove benzene from the air, but also to separate benzene from cyclohexane, which is an important industrial product often prepared from benzene,” said Professor Martin Schröder, lead author of the paper, which was published in Chem.
“Because of the small difference in their boiling points (just 0.6℃) the separation of benzene and cyclohexane is currently extremely difficult and expensive to achieve via distillation or other methods.”
Conventional adsorbents, such as activated carbons and zeolites, often suffer from structural disorder which can restrict their effectiveness in capturing benzene.
The research also includes a study of how and why the new materials work.
“The crystalline nature of MOF materials enables the direct visualisation of the host-guest chemistry at the atomic scale using advanced diffraction and spectroscopic techniques,” said Professor Sihai Yang, another lead author of the paper.
“Such fundamental understanding of the structure-property relationship is crucial to the design of new sorbent materials showing improved performance in benzene capture.”
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