Densification and shaping of pure Cu-BTC powders using a solid-state chemical transformation

Abstract

MOFs are a class of porous crystalline materials whose unique properties have led to applicability in several fields ranging from gas adsorption to drug delivery. Despite their high potential, MOFs are usually found as fine powders, a property that can limit their use in industrial applications. Here, a novel approach is proposed to form densified Cu-MOF (Cu-BTC) powders and monoliths using 1,2-ethanedisulfonic acid (EDSA) as a densification agent. A MOF/EDSA mixture was heated to ∼150 °C; the molten EDSA not only promotes the growth of larger MOF crystallites, but also stimulates condensation reactions between the carboxylate-based MOF ligands, further binding the particles together. When this reaction was done in a stainless-steel die under pressure MOF-based monoliths could also be formed. Notably, using this approach, the MOF had a higher density, significantly improving the volumetric CO2 adsorption capacity. We believe this contribution provides the basis for future work wherein the intrinsic MOF particle surfaces can be selectively engineered to improve their properties towards shaping for industrial applications.