Additive manufacturing of architected Ca(OH)2 monoliths for accelerated CO2 mineralization

• Printable Ca(OH) 2 ink was developed for DIW 3D printing of structured sorbents • Achieved >99% carbonation across wide CO 2 concentrations from 10 mol% to 400 ppm • The printed monolith exhibits a low pressure drop structure suitable for scalable CO 2 capture • Techno-economic analysis (TEA) demonstrates the feasibility of DAC via DIW 3D printing Effective CCU technologies demand robust, scalable sorbents with high CO 2 selectivity and capacity. While calcium hydroxide (Ca(OH) 2 ) offers high CO 2 uptake via mineral carbonation, its practical application is hindered by slow reaction kinetics and difficulties in forming mechanically stable, structured beds. Here, we report a direct ink writing (DIW) approach to fabricate 3D-printed Ca(OH) 2 monoliths using water-based inks formulated with carboxymethyl cellulose (CMC). Under humid conditions (RH95, 1 − 10 mol% CO 2 ), the monolith achieves > 99% conversion to calcium carbonate, with similarly strong performance maintained at 400 ppm CO 2 relevant to direct air capture (DAC). The structured sorbent also exhibits extremely low pressure drop (∼2 Pa/cm), making it suitable for scaled-up applications. A techno-economic analysis (TEA) for the DAC case, incorporating parallel nozzle printing, shows that the levelized cost of capture (LCOC) can be reduced to 339 US$/tCO 2 , with break-even scenarios attainable through carbon subsidies or high-value reuse of the monolith reuse. Overall, this work establishes a dry, scalable pathway for fabricating reactive structured Ca(OH) 2 sorbents for CCU applications.