The dynamic nature and flexibility of the molecular sieve is crucial to understanding its performance for transporting small molecules. Credit: University of Liverpool
Researchers at the University of Liverpool and the University of Technology and King Abdullah have reported some interesting findings related to the metal-organic framework (MOF), a class of porous materials, which can benefit some important gas separation processes. The findings are reported in two research papers.
Metal-organic frameworks (MOFs) are a newer class of porous, crystalline materials and a wide range of applications.
Some MOFs can act as a molecular sieve, allowing one type of gas molecule of the mixture to penetrate while blocking another. For example, it is known that some MOF separates propylene from propane, an important process in the manufacture of polypropylene plastics that require high purity propylene.
In his first paper published on Natural Communication, researchers suggest that unlike kitchen sieves, these three-dimensional molecular filters can change the shape of the pores and their flexibility is very important for this performance.
Calculation of high-output gas transport properties in thousands of porous materials identifies materials that indicate potential for energy-saving gas separation in the chemical industry. Credit: University of Liverpool
Computational models supported by experimental X-ray data indicate that for such a high-performance MOF, called KAUST-7, structural changes in MOF are triggered by the presence of different propylene gas propane and propane molecules resulting in stronger adsorption and faster transport of propylene and thus essentially sift the propane molecules out.
However, it is difficult to predict other types of MOF that have this functional flexibility and are thought to be good for a given gas separation because their performance is controlled by specific molecular interactions that are difficult to anticipate or identify experimentally.
In the second paper published on Physical Chemistry, researchers focus on this challenge.
They developed a computational filtering approach to evaluate the more than four thousand MOFs reported in advance for their flexibility when acting as a molecular sieve. Using this approach, they identified the top four MOFs that showed the potential to separate their propylene from propane – two of which were reported to have performed well while the others had not been tested for this application experimentally.
Dr Matthew Dyer, a lecturer in Chemistry and part of the Leverhulme University Research Center for Functional Material Design, said: “The MOF has attracted a lot of interest in the last few years and there is hope for technical applications specifically for flexible MOF.
“Our research adds to our knowledge of MOFs, whether some of us are able to act as a sieve which goes to show flexibility.
“Using a computational approach, we can identify flexible MOFs and these findings could potentially make the gas purification process more energy efficient. It is important to produce high quality plastics that require pure initial compounds that are usually extracted from gas products in petrochemical processing.”
“Such a high throughput filtering approach can be applied to many different materials with different potential applications. They have the potential to change the way we find material to face technological challenges.”
references:
“Different guest locations with host dynamics enhance propylene / propane separation in a metal-organic framework” by Dmytro Antypov, Aleksander Shkurenko, Prashant M. Bhatt, Youssef Belmabkhout, Karim Adil, Amandine Cadiau, Mikhail Suyetin, Mohamed Eddaoudi, Matthew J. Rosseinsky and Matthew S. Dyer, November 30, 2020, Natural Communication,
DOI: 10.1038 / s41467-020-19207-9
“High-yield metal-organic framework for propane and propane separation kinetics” by John Pramudy, Satyanarayana Bonakala, Dmytro Antypov, Prashant M. Bhatt, Aleksander Shkurenko, Mohamed Eddaoudi, Matthew J. Rosseinsky and Matthew S. Dyer, October 6, 2020 , Physical Chemistry,
DOI: 10.1039 / D0CP03790G
The Leverhulme Center for Research Centers for Functional Material Design is an interdisciplinary research center that aims to revolutionize new material design. It combines advanced chemistry and computer science to develop new approaches to the design of functional materials on an atomic scale.