High-Entropy Fluorite Oxide-Modified CaO-Based Sorbent Pellets for Enhanced High-Temperature CO₂ Capture

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Calcium looping is crucial for CO2 capture from flue gas using calcium oxide (CaO)-based sorbents.
• CaO sorbents suffer from low thermodynamic stability and sintering, limiting their cyclic performance.

Purpose of the Study:

• To develop a novel high-entropy fluorite oxide (HEFO) stabilizer to improve the anti-sintering properties and cyclic stability of CaO-based sorbents.
• To investigate the synthesis and performance of HEFO-modified CaO sorbent pellets for enhanced CO2 capture.

Main Methods:

• Synthesis of HEFO-modified CaO sorbent pellets using a rapid cigarette butt-assisted combustion process and graphite molding.
• Evaluation of CO2 capture capacity and cyclic stability through multiple capture-regeneration cycles.
• Analysis of morphological, crystallographic, and binding energy changes to understand anti-sintering mechanisms.

Main Results:

• HEFO modification significantly enhanced the anti-sintering properties and cyclic stability of CaO-based sorbents.
• The CO2 capture capacity reached 0.373 g g⁻¹, a 2.6-fold improvement over pure CaO.
• HEFO's entropy stabilization and strong CaO affinity (-1.83 eV interface binding energy) restricted CaO migration and sintering.
• Synergistic effects of HEFO reduced energy barriers, increasing carbonation and calcination rates by 40% and 140%, respectively.

Conclusions:

• Rapidly synthesized HEFO-modified CaO sorbent pellets offer superior CO2 capture performance and cyclic stability.
• The HEFO stabilizer effectively mitigates sintering issues in CaO-based sorbents.
• These sorbents show significant potential for industrial applications in CO2 capture technologies.