Direct CO₂ Conversion Using Geological Carbonates as Absorbents for an Integrated Carbon Capture-Conversion Strategy

Area of Science:

• Chemical Engineering
• Catalysis
• Environmental Science

Background:

• Conventional carbon capture and utilization (CCU) methods are energy-intensive due to high regeneration and material cycling costs.
• Natural carbonate weathering efficiently sequesters CO2, offering inspiration for sustainable CCU.

Purpose of the Study:

• To develop an integrated, energy-efficient CO2 capture and conversion strategy.
• To utilize abundant, low-cost carbonates as absorbents for CO2 capture.
• To achieve in situ hydrogenation of captured CO2 to formate.

Main Methods:

• Employed a one-pot system using geologically abundant carbonates as absorbents.
• Utilized a cobalt-copper (CoCu) catalyst for in situ hydrogenation of absorbed CO2.
• Investigated CO2 capture and conversion at 140 °C with diluted CO2 streams (50,000 ppm).
• Performed density functional theory (DFT) calculations to elucidate reaction mechanisms.

Main Results:

• Achieved a 21% yield of formate from CO2 capture and hydrogenation.
• Demonstrated efficient in situ conversion of CO2 absorbed by carbonates.
• Identified a synergistic CoCu catalyst facilitating CO2 hydrogenation.
• DFT calculations revealed the Cu+/Cu0 interface as the active site for H2 activation and formate production.

Conclusions:

• The proposed integrated strategy offers a sustainable and energy-efficient pathway for CCU.
• The CoCu catalyst and carbonate-based capture system significantly enhance CO2 conversion efficiency.
• This approach advances CCU technologies by mimicking natural carbon sequestration processes.