MOF immobilization on the surface of polymer-cordierite composite monoliths through in-situ crystal growth

Scalable fabrication methods to concentrate metal-organic frameworks (MOFs) on the surface of monoliths are highly desirable for their deployment at an industrial scale. In this study, we report the growth of a thick layer of MOF film on the surface of Torlon-monolith composite adsorbent. In our previous work, we demonstrated immobilization of MOFs on monolithic substrates by various techniques including layer-by-layer + secondary growth and in-situ dip coating. Although these earlier methods showed promising results, the MOFs weight loading did not exceed 55 wt%. Here we demonstrate the improvement in coating a thicker film of MOF on the monolith walls using a novel technique that involves pre-seeding of MOF powder onto the monolith using a Torlon polymer solution. This coating procedure is not only simpler and eliminates the complexity of previously reported procedures, but also results in higher MOF loadings. Whereas the earlier loading was 52 wt% for MOF-74 (Ni) and 55 wt% for UTSA-16 (Co), the new loading has been found to be ∼73 wt% for MOF-74 (Ni) and a maximum of ∼80% for UTSA-16 (Co). In addition, the substrates treated with this new method have shown improved CO2 adsorption capacities with similar kinetics to that of the earlier method. This simple method opens up fascinating possibilities for scalable fabrication of MOF-coated monoliths with tuned properties tailored to various gas separation applications.