Mid-temperature CO₂ Adsorption over Different Alkaline Sorbents Dispersed over Mesoporous Al₂O₃

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Developing efficient carbon dioxide (CO2) adsorbents is crucial for mitigating climate change.
• Mid-temperature CO2 capture (around 300°C) requires robust materials with high capacity and stability.

Purpose of the Study:

• To synthesize and characterize alkaline sorption active phases on mesoporous alumina for CO2 adsorption.
• To evaluate the CO2 adsorption capacity, kinetics, and thermodynamics of these materials.
• To assess the material's stability for reversible CO2 capture applications.

Main Methods:

• Preparation of CO2 adsorbents using alkaline phases (e.g., Na2O) on mesoporous Al2O3.
• Characterization using X-ray Diffraction (XRD), N2 physisorption, CO2-Temperature Programmed Desorption (CO2-TPD), and Transmission Electron Microscopy (TEM).
• Testing CO2 adsorption capacity, kinetics, thermodynamics, and cyclic stability at mid-temperatures.

Main Results:

• Na2O supported on Al2O3 exhibited the highest CO2 adsorption capacity due to interfacial Al-O-Na+ sites.
• Optimal Na2O loading was 12 wt% (0.22 Na/Al molar ratio).
• The Na2O/Al2O3 material showed exothermic adsorption fitting the Avrami model and Langmuir isotherm, with excellent cyclic stability.

Conclusions:

• Na2O/Al2O3 is a promising reversible CO2 chemisorbent for mid-temperature applications.
• The material's nanostructure and porosity remained intact after multiple adsorption-desorption cycles.
• This adsorbent can also serve as a support for dual-function materials.