Magnetic induction swing adsorption: An energy efficient route to porous adsorbent regeneration

Metal Organic Frameworks (MOFs) are promising nanomaterials with unprecedented capacity to store small molecules. Despite this huge capacity, proposed methods to release these molecules are not yet feasible at a meaningful scale, largely due to the strong binding of the molecules and the thermally insulating nature of the adsorbent. It is likely that large amounts of energy would be required for operation at scale. Furthermore, the high adsorption capacity of MOFs is not typically matched by a high working capacity – adsorbed molecules are not readily retrieved. Here we show a series of magnetic framework composites (MFCs) synthesized from ferri-magnetic MgFe₂O₄ nanoparticles and the Zr-based MOF UiO-66 can be deployed in a magnetic induction swing adsorption (MISA) process for CO₂ capture and release. Exposure of the MFCs to alternating current magnetic field resulted in heat generation by the embedded magnetic nanoparticle and fast CO₂ release from the MOF, with an unprecedented 100 % of adsorbed CO₂ released under a 42 mT field. This was achieved at a regeneration time of 240 s. The efficiency of the MISA process was shown to be dependent on the amount of MFC used, with efficiencies reaching 60 % at just a gram scale. These local ‘nanoheaters’ overcome the thermally insulating nature of the adsorbent, which has promising implications for use at scale. Additionally, the ability to access 100 % of the adsorption capacity enables the use of strongly adsorbing, high capacity MOFs previously discarded.