3D-printed zeolite 13X gyroid monolith adsorbents for CO2 capture

Abstract

Self-standing 3D-printed gyroid monoliths of zeolite 13X were fabricated for the first time for carbon dioxide adsorption. Gyroid sheet-based triply periodic minimal surface (TPMS) lattices provide high surface area per unit volume, smooth surfaces with no discontinuities, and low pressure drop compared to powder and beads, which are essential in gas adsorption. A photopolymer resin and zeolite 13X powder slurry was 3D-printed by digital light processing followed by debinding to remove the polymer and sintering to diffuse and consolidate the zeolite 13X particles. The sintered adsorbents were mechanically stable, and structural and morphological analyses revealed the interconnected nature of the gyroid cells permitting CO2 molecules to easily diffuse into the printed structure, thus ensuring sufficient adsorbent/adsorbate contact. The gyroid zeolite monoliths reached an equilibrium adsorption capacity of 3.5 mmol g−1 in 77 min at 25 °C and 1 bar, whereas the beads and powder required 96 and 100 min, respectively, while after 20 pressure swing adsorption (PSA) cycles, the zeolite monolith showed sustainable performance compared to the powder. The CO2/N2 selectivity ranged from 328 (at 50 mbar) to 51 (at 1 bar) at 25 °C for the zeolite monolith, whereas the powder exhibited selectivity values in the range of 294 (at 50 mbar) to 33 (at 1 bar). Dynamic breakthrough experiments using CO2/N2 mixtures confirmed the fast kinetics and separation performance of the monoliths, while the pressure drop was also significantly lower than the powder and the beads. The novel topology of the developed self-standing gyroid zeolite monoliths eliminate the need for structuring of powdered adsorbents and exhibit competitive performance, enhanced kinetics and cyclability, and reduced pressure drop toward large-scale carbon capture application.