Dynamics of Core–Shell-Structured Sorbents for Enhanced Adsorptive Separation of Carbon Dioxide

One of the key environmental problems underlying climate change and global warming is the persistent increase in atmospheric carbon dioxide concentration. Carbon capture and storage (CCS) systems can be based on, among others, solid porous sorbents (e.g., zeolites). A promising alternative to traditionally used sorbents may be appropriately structured hybrid adsorbents. With the proper geometry and synergistic combination of the sorbent with another material, e.g., a catalyst or a substance with certain useful physical features, they can gain new properties. The present study examined the dynamics of CO₂ sorption in core–shell particles and, as a reference, in particles with a uniform structure. It was assumed that the sorbent (zeolite 5A) incorporated in a single particle had the form of microcrystals, which implies a bidisperse particle structure. As a second particle-forming material, a nickel catalyst (behaving as an inert) was adopted. The computational results confirmed that particle structure can provide an additional design parameter for adsorption columns and adsorptive reactors. The sorption-inactive shell proved to play a protective role when thermal waves moved through the bed. In addition, an important element determining sorption dynamics in core–shell particles was revealed to be the structure (e.g., mean pore diameter) controlling intraparticle mass transport.