CaO-Based CO₂ Sorbents Effectively Stabilized by Metal Oxides.

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Calcium looping is a key carbon dioxide (CO2) capture technology using calcium oxide (CaO).
• Limestone-derived CaO sorbents suffer from rapid capacity decay due to sintering under harsh conditions.
• Developing cyclically stable and high-capacity sorbents is crucial for effective CO2 capture.

Purpose of the Study:

• To synthesize cyclically stable, high-performance CaO-based CO2 sorbents.
• To investigate the effect of metal oxides on sorbent stability and CO2 uptake.
• To establish a relationship between sorbent morphology and CO2 capture capacity.

Main Methods:

• Utilized the Pechini method for synthesizing CaO-based sorbents.
• Incorporated single (Al2O3, Y2O3) and bimetal oxides (Al2O3-Y2O3) into the CaO matrix.
• Evaluated sorbent performance over 30 cycles of calcination and carbonation.

Main Results:

• Sorbents synthesized via the Pechini method exhibited compositional homogeneity and nanostructured, porous morphology.
• Al2O3 and Y2O3 (single or bimetal) addition enhanced cyclic stability, unlike MgO.
• The best performing sorbent (equimolar Al2O3-Y2O3) achieved 8.7 mmol CO2 g-1 after 30 cycles, a 360% increase over limestone.

Conclusions:

• The Pechini method enables the synthesis of highly stable and effective CaO-based CO2 sorbents.
• Nanostructured morphology and specific metal oxide additives (Al2O3, Y2O3) are key to improved cyclic stability and CO2 uptake.
• These advanced sorbents show significant potential for next-generation CO2 capture technologies.