Dynamics of solid amine sorbent packed-bed reactors for carbon dioxide capture: Interplay between particle characteristics and pumping energy

The design of solid-amine fixed-bed reactors for CO 2 capture is fundamentally limited by the tight coupling between convection, adsorption kinetics, and intra-particle diffusion, yet current guidelines typically rely on oversimplified assumptions that fail under high-productivity operation. Here, we develop a unified dimensionless framework, based on the Damköhler number ( Da ) and the particle transport number ( Θ p ), that systematically delineates the multiscale regimes governing reactor performance. A comprehensive simulation campaign with the validated model shows that high capture efficiency ( η > 95 % ) and minimal pumping power occur at elevated Da ∼ 10 − 10 3 and moderately high Θ p ≃ 50 , where particle-scale transport is relatively slow, yet hydrodynamic penalties remain manageable. Translating these optimal dimensionless numbers into physical parameters demonstrates that industrially relevant high-throughput operation demands high specific surface areas in the range of 10 4 m 2 g − 1 and relatively small particle diameters on the order of 0.1 − 1 mm . The analysis further highlights the need for sorbents with hierarchical porosity and enhanced thermal conductivity to reduce regeneration energy and synchronize heat-mass transport. Overall, this work provides a predictive and generalizable blueprint for engineering next-generation, low-energy, high-productivity CO 2 capture systems. • A multiscale CO 2 capture model at the reactor and particle scales is presented. • A comprehensive analysis is conducted in terms of relevant dimensionless parameters. • Efficient capture requires convective time larger than particle/adsorption times. • Efficiency and pumping power can be optimized at Da ∼ 10 − 10 3 and Θ p ≃ 50 . • High throughput needs 10 4 m 2 / g and 0.1 − 1 mm particles.