Dual Alkali Solvent System for CO₂ Capture from Flue Gas

Area of Science:

• Chemical Engineering
• Environmental Science
• Materials Science

Background:

• Traditional CO2 capture systems utilize a single solvent for both absorption and stripping.
• This can lead to high energy penalties, particularly during the solvent regeneration (stripping) phase.
• Developing more energy-efficient CO2 capture technologies is crucial for mitigating climate change.

Purpose of the Study:

• To introduce and evaluate a novel two-aqueous-phase CO2 capture system, the dual alkali solvent (DAS) system.
• To demonstrate the potential for energy savings and simultaneous pollutant capture using the DAS system.
• To compare the performance of the DAS system with existing CO2 capture processes like the Econamine process.

Main Methods:

• Development of a two-aqueous-phase solvent system comprising an upper organic alkali phase (1-(2-hydroxyethyl) piperazine - HEP) and a lower K2CO3/KHCO3 aqueous phase.
• Investigating the phase separation, CO2 absorption, and CO2 transfer mechanisms within the DAS system.
• Conducting preliminary experiments and simulations to assess energy consumption and capture efficiency.

Main Results:

• The DAS system successfully achieved phase separation and efficient CO2 absorption (∼90%).
• The system demonstrated significant CO2 stripping energy savings of 24.0% compared to the Econamine process.
• The DAS system enables simultaneous capture of CO2 and SO2/SO3 from flue gas due to the presence of K2CO3/KHCO3 in the lower phase.

Conclusions:

• The dual alkali solvent (DAS) system represents a promising advancement in CO2 capture technology.
• The DAS system offers substantial energy savings in the stripping process and potential for co-capture of pollutants.
• Further research and development of the DAS system could lead to more sustainable and cost-effective carbon capture solutions.