Innovative materials known as metal organic frameworks (MOFs) could become much more versatile after research shows that they can be manipulated in liquid form.
MOFs are highly porous crystalline solids with metal ions or metal clusters bound together by organic (carbon-based) bonding groups. Changing these parts can produce large amounts of solids with internal pores that can trap selected molecules or catalyze chemical reactions.
“These crystalline materials are difficult to handle, but we have developed a way to dissolve them,” said Anastasiya Bavykina, of the research team at the KAUST Catalytic Center.
The KAUST researchers have produced MOF-based films embedded in a polymer, which they think can achieve a remarkable efficiency in separating propylene from propane.
“This is a revolution,” Bavykina said. Propylene is the main raw material for the chemical industry; It is used to manufacture polypropylene polymers that are used in many products. It can also be converted to other polymers and industrially useful chemicals, but it must first be separated from the propane it is normally associated with.
Co-author Shuvo Datta points out: “If today’s energy-intensive propane-propylene extraction technology, based on distillation, could be replaced by our MOF membrane technology, this could be saving about 0.1% of global energy consumption ”.
One challenge for the team is to make a crystal MOF act like a porous liquid. The team discovered how to alter the surface of the MOF nanoparticles relatively large with suitable chemical groups. This “surface functionalization” allows the nanoparticles to form stable dispersions in a liquid solvent.
Another challenge is to ensure that the inner holes of MOFs remain empty and able to absorb and allow the desired gas molecules to penetrate. The gaps and solvent molecules must be carefully controlled to prevent solvent from filling in gaps.
“It is not so easy to prove that the liquid is porous,” says Bavykina. Researchers had to develop a new experimental setup to achieve this.
MOF dispersion in the liquid phase could separate the bubbled gas mixtures through them, but the team achieved greater flexibility by incorporating MOFs into their rigid, flexible polymer films. This allows the continuous flow system to run for up to 30 days, generating 97% pure propylene from a 50/50 propane-propylene mixture that has been efficiently filtered by a membrane.
The team now wants to expand their process to demonstrate its commercial potential. They will also seek to apply it to other important industrial gas separation processes.
Research is published in Natural materials.
The metal-organic framework cuts the energy consumption of petrochemicals
A treatable metal-organic framing solution for mixed matrix films using porous liquids, Natural materials, DOI: 10.1038 / s41563-020-0764-y, www.nature.com/articles/s41563-020-0764-y
Provided by King Abdullah University of Science and Technology
Quote: Metal organic framework created to act like liquids (2020, August 10) retrieved August 12, 2020 from https://phys.org/news/2020-08-metal-frameworks -liquids.html
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