Integrated Flue Gas CO₂ Capture and Conversion to Formate: A Sustainable Approach.

Area of Science:

• Catalysis
• Chemical Engineering
• Environmental Science

Background:

• Industrial CO2 emissions pose significant environmental challenges due to dilute streams and impurities.
• Conventional CO2 capture technologies often lack energy efficiency and struggle with complex flue gas compositions.

Purpose of the Study:

• To develop an energy-efficient and contaminant-tolerant system for direct CO2 capture and conversion.
• To investigate the catalytic performance and stability of a heterogenized iridium complex for CO2 valorization.

Main Methods:

• An integrated CO2 capture and conversion (ICCC) system was designed using a hydroxyquinoline-ligated Cp*Ir-Cl catalyst immobilized on amine-functionalized silica.
• The catalyst's performance was evaluated using synthetic flue gas containing SOx, NOx, and O2.
• Density functional theory (DFT) was employed to elucidate the catalyst's structure-activity relationship.

Main Results:

• The ICCC system achieved 100% selectivity for formate production from CO2.
• The catalyst demonstrated high activity with turnover numbers up to 10,286 within 16 hours.
• The system exhibited excellent durability over five regeneration cycles, maintaining full activity.

Conclusions:

• The developed heterogenized iridium catalyst offers a sustainable and recyclable platform for CO2-to-formate conversion.
• The catalyst's unique structure enhances its stability and efficiency in complex industrial flue gas conditions.
• This closed-loop strategy shows strong potential for scalable industrial CO2 mitigation.