Metal-Organic Framework: A cost-efficient, greener way to generate Oxygen

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The second wave of Coronavirus pandemic posed challenges in the form of acute shortage of oxygen across the world and India also faced the wrath of the ever-spreading infection. In order to overcome the crisis, Indian researchers indulged in rapidly responding to the situation by innovating technologies to support the medical infrastructure of the country. Aligning with this, the Central University of Punjab and Maharaja Ranjit Singh Punjab Technical University have developed in conjunction a Metal-Organic Framework (MOF) that would play a pivotal role in tackling oxygen shortage. The essential steps are taken to face the unprecedented challenges of the future.

*Metal-Organic Framework: How is it better than other technologies for oxygen separation?*

Pure molecular oxygen is essential to many industrial areas that include steel production, oxy-fuel combustion, medical oxygen concentrators, on-board oxygen generation in military aircraft etc. Thus, cryogenic air concentrators are conventionally employed in carrying out industrial-scale oxygen separation. Although cryogenic air separation produces high-quality oxygen (with 99% purity), on the downside, it is energy-intensive, expensive and requires large housing facilities.

On the other hand, to overcome the downsides of cryogenic separation technology, Pressure Swing Adsorption (PSA) came into force. This technology can carry out oxygen separation on a comparatively smaller scale, but its application is limited to synthesize processes that would require lower purity O2. The processes by PSA depend on adsorbents such as zeolites to capture Nitrogen (N2) from the air but it is worth noting that, zeolites are high-priced, inefficient and incapable of producing high oxygen purity.

Now, to counter this, and come up with a better solution in order to meet the demand for an efficient supply of oxygen that is cost-effective, researchers have looked to the Metal-Organic Framework (MOFs). Metal-organic frameworks are considered largely unexplored alternatives to selective adsorption of oxygen. With their intriguing network structures, they are crystalline, porous materials with large internal surface areas that can be highly selective for a certain molecule during synthesis. Most researchers design MOFs to be highly selective of Oxygen over Nitrogen which tends to result in the simultaneous separation of Nitrogen and other air components from Oxygen. The MOFs are capable of producing a purer form of oxygen when the technology is incorporated into the PSA process, competing with the purity of cryogenic air separation. Among various benefits of using this technology includes better sorbent purity, fewer structural defects, and MOFs can store greater amounts of adsorbents in comparison to zeolites. Further, MOFs process the oxygen separation under mild conditions (ambient pressure and temperature), revolutionising the swing adsorption process, which in turn, increase the prospective usage in the application fields.

*Technology to aid patients in Rural Areas*

The current pandemic posed challenges that were unforeseen and adequate medical equipment to treat the patients of COVID-19 in the remotest areas of the country became the need of the hour. Hence, in order to provide oxygen supply at affordable prices, MOFs can be used as substitutes for costly zeolites and molecular sieves that are being used commercially. As mentioned above, cryogenic oxygen production is energy-intensive and requires large housing facilities, MOFs can come as a rescue and serve as a contingency plan for the development of robust medical infrastructure in rural India.