Sol-Gel Processing of a Covalent Organic Framework for the Generation of Hierarchically Porous Monolithic Adsorbents

Covalent organic frameworks (COFs) have emerged as a versatile materials platform for applications including chemical separations, water purification, chemical reaction engineering and energy storage. Their inherently low mechanical stability, however, frequently renders existing methods of pelletisation ineffective contributing to pore collapse, pore blockage or insufficient densification of crystallites. Here, we present a general process for the shaping and densifying of COFs into centimetre-scale porous monolithic pellets without the need for templates, additives or binders. This process minimises mechanical damage from shear-induced plastic deformation and further provides a network of interparticle mesopores that we exploit in accessing analyte capacities above those achievable from the intrinsic porosity of the COF framework. Using a lattice-gas model, we accurately capture the monolithic structure across the mesoporous range and tie pore architecture to performance characteristics in both gas storage and separation applications. Collectively, these findings represent a substantial step in the practical applicability of COFs and other mechanically weak porous materials.