CaO-based sorbent derived from lime mud and bauxite tailings for cyclic CO₂ capture

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Calcium oxide (CaO)-based sorbents are crucial for post-combustion CO2 capture.
• The long-term stability and efficiency of these sorbents are key challenges.
• Doping CaO with various materials can enhance CO2 absorption properties.

Purpose of the Study:

• To investigate the effect of aluminum nitrate (AlN) and bauxite tailings (BTs) as dopants on CaO-based sorbents for CO2 capture.
• To evaluate the cyclic carbonation/calcination performance and stability of these modified sorbents.
• To explore the potential of utilizing waste materials like BTs in CO2 capture sorbents.

Main Methods:

• Preparation of CaO-based sorbents using lime mud (LM) and dopants (AlN, BTs) via dry mixing.
• CO2 capture performance evaluation using thermogravimetric analysis (TGA) over multiple cycles.
• Characterization of sorbent phase composition and morphology using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Main Results:

• The AlN-doped sorbent exhibited a high absorption conversion of 30.88% after 30 cycles.
• The BTs-doped sorbent showed lower initial conversion but superior cyclic absorption stability.
• The formation of Ca12Al14O33 phase in AlN-doped sorbents contributed to enhanced stability.

Conclusions:

• AlN doping enhances the CO2 absorption capacity and stability of CaO-based sorbents.
• BTs doping offers a cost-effective and environmentally friendly approach with improved cyclic stability, despite lower initial conversion.
• The findings suggest potential for developing durable and economical CO2 capture materials from waste.