Advanced High-Temperature CO₂ Sorbents with Improved Long-Term Cycling Stability

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Developing efficient sorbents is crucial for sequestering anthropogenic carbon dioxide (CO2).
• Calcium oxide (CaO)-based sorbents offer potential but require stabilization and support for optimal performance.
• Existing limestone-derived CaO (L-CaO) sorbents have limitations in capture capacity and stability.

Purpose of the Study:

• To develop novel CaO-based sorbents stabilized by MgO and supported by in situ generated carbon.
• To evaluate the CO2 capture efficiency and cycling stability of these mixed metal oxide (MMO) sorbents.
• To compare the performance of the synthetic MMO sorbents against benchmark L-CaO sorbents.

Main Methods:

• Green synthesis of CaO-based sorbents stabilized with varying MgO content (10-30 wt %).
• Support generation using in situ carbon under an inert atmosphere.
• Screening of MMO sorbents for high-temperature CO2 capture (650 °C, atmospheric pressure) using CO2-rich (86%) and CO2-lean (14%) gas streams.

Main Results:

• MMO sorbents achieved 53-63 wt % CO2 capture with ~98% carbonation efficiency, significantly outperforming L-CaO (22.8 wt %).
• All synthetic MMO sorbents demonstrated superior capture capacity and cyclic stability compared to L-CaO.
• The g-Ca0.69Mg0.3O sorbent retained ~65% of its initial CO2 capture capacity after 100 cycles under lean CO2 conditions.

Conclusions:

• Green synthesized MMO sorbents exhibit high CO2 capture efficiency and excellent cycling stability.
• These novel sorbents represent a promising advancement for effective anthropogenic CO2 sequestration.
• The g-Ca0.69Mg0.3O sorbent shows exceptional potential for long-term CO2 capture applications.