Direct synthesis and Additive Manufacturing of binderless Zeolite A monoliths for efficient CO2 capture
Abstract
Zeolite A is a highly selective CO₂ adsorbent and a promising candidate for Carbon Capture processes. Conventional manufacturing of zeolite A relies on hydrothermal synthesis of powders, followed by energy-intensive shaping to achieve suitable mechanical and mass transfer properties. Here we present a novel and scalable strategy for the direct synthesis of structured phase-pure zeolite A monoliths, that entirely bypasses hydrothermal processing and powder shaping. By using a highly concentrated gel, net-shape zeolite A adsorbents with optimised macroporous architectures are obtained through in-situ crystallisation, without binders, extrusion, or post-synthetic zeolitisation. The rheological properties of the gel enables Direct Ink Writing, allowing precise 3D shaping of hierarchical porous monoliths with tunable geometries. To validate this approach, LTA monoliths with three different designs (Fractal, Scaffold and Hybrid) are produced, characterised and tested for CO₂ adsorption under static and dynamic conditions. They outperform commercial zeolite A beads, achieving higher static adsorption capacity and superior dynamic performance, especially the Fractal architecture, which exhibits steeper breakthrough curves and shorter breakthrough times. A new paradigm in zeolite monolith fabrication is established, synergically combining scalable, low-cost synthesis, advanced 3D shaping, binderless composition, structure adaptability, and mechanical robustness to unlock next-generation adsorbents for efficient CO₂ capture