CO2 Capture by Vat-Printed and Photopolymer-Derived Structures: Uptake Mechanisms, Mass Transfer, Regeneration and Qualification

Additive manufacturing is increasingly used to shape carbon-dioxide capture media into monoliths, lattices and structured reactors. The underlying materials, however, span fundamentally different states. Published work includes direct-ink-written silicone/sodium-carbonate composites that retain the polymer matrix, DLP-printed zeolite 13X and Li4SiO4 structures in which a photopolymer enables shaping but is subsequently removed or converted, and 3D-printed activated-carbon monoliths evaluated by adsorption and breakthrough methods. These systems cannot be pooled into a single CO2-capture number. Uptake depends on gas composition and partial pressure, temperature, humidity, active-phase loading, accessible porosity, specimen geometry, flow regime, equilibration time, reaction stoichiometry and whether the process is reversible. This Engineering Review separates physisorption, absorption, chemisorption and irreversible carbonation/mineralisation; distinguishes equilibrium capacity from working capacity and transient mass gain; maps architecture-to-mass-transfer effects; and proposes minimum mass-balance, cycling and product-identification requirements. 3Dresyn CDC1 is included only as manufacturer implementation context. A manufacturer catalogue statement of up to 300 g CO2 per kg of material converted into calcite is treated only as manufacturer information, not independent evidence, and is not qualified by this review without a controlled product-specific capture/conversion mass balance.