Understanding Material Compatibility in CO₂ Capture Systems Using Molten Alkali Metal Borates

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Molten alkali metal borates are proposed as energy-efficient sorbents for high-temperature carbon dioxide (CO2) capture.
• These sorbents offer a potential solution for mitigating global warming by capturing CO2 from industrial emissions.

Purpose of the Study:

• To evaluate material compatibility challenges associated with molten alkali metal borates under harsh operating conditions.
• To identify suitable materials that can withstand corrosive environments and maintain sorbent performance for effective CO2 capture.

Main Methods:

• Investigated the performance of various materials, including common ceramics, steels, superalloys, platinum, and Nickel 200/201 alloy.
• Assessed material degradation through corrosive oxidation and chemical degradation in molten salts.
• Quantified sorbent capacity changes and corrosion rates over extended operational periods.

Main Results:

• Common materials like ceramics, steels, and superalloys showed significant degradation and reduced sorbent capacity.
• Platinum exhibited excellent stability with minimal performance change (<0.1% over 1000 h).
• Nickel 200/201 alloy demonstrated optimal performance, with modest corrosion rates (0.3-0.5 mm/year) and manageable sorbent capacity loss (0.5-20% over 100 h).

Conclusions:

• Material compatibility is a critical challenge for molten alkali metal borate sorbents.
• Nickel 200/201 alloy presents a promising material solution for high-temperature CO2 capture systems.
• Further protective measures and research are needed to ensure long-term viability and scalability of these sorbents for carbon emission reduction.