High Water Tolerance of a Core-Shell-Structured Zeolite for CO₂ Adsorptive Separation under Wet Conditions

Dehumidification in CO₂ adsorptive separation processes is an important issue, owing to its high energy consumption. However, available adsorbents such as low-silica zeolites show a significant decrease in CO₂ adsorption capacity when water vapor is present. A core-shell-structured MFI-type zeolite with a hydrophilic ZSM-5 coated with a hydrophobic silicalite-1 shell layer was applied in CO₂ adsorptive separation under wet conditions. This hybrid material demonstrated remarkably high water tolerance with stable CO₂ adsorption performance without additional thermal treatment for regeneration, whereas a significant decrease in the CO₂ adsorption amount because of water vapor was observed on the parent ZSM-5. The core-shell structure of zeolites with high pore volumes, such as LTA or CHA, could also be suitable candidates for high CO₂ adsorption capacity and high water tolerance for practical applications.