Solubility and energy analysis for CO2 absorption in piperazine derivatives and their mixtures

• CO2 solubility in aqueous piperazine derivatives and mixtures with PZ were measured.
• These piperazine derivatives include 1-MPZ, 1-EPZ, HEP, DMPZ, TEDA.
• Cyclic solubility of CO2 in these solvents has been compared with three methods.
• Heats of absorption and reboiler heat duty have also been calculated.
• 1-MPZ + PZ, 1-MPZ, TEDA + PZ and DMPZ + PZ are suggested solvents for CO2 capture.

Solvent is a critical part of the post-combustion CO2 capture process by chemical absorption. Processes using good solvents will have low regeneration duty, high absorption rate, high cyclic capacity, and good resistance to degradation. This study focuses on the screening of cyclic amines (single or blended) of piperazine (PZ) derivatives based on the detailed VLE experiments for CO2 solubility, and analysis through simplified process modelling. With the proposed methodology, a new solvent can be efficiently compared with others in terms of operational cyclic capacity and regeneration duty. The study results showed that the most promising solvent candidate in terms of projected reboiler duty with a value of 2.5 MJ/kg is the mixture of 1-MPZ and PZ. Considering the impact of cyclic capacity on the overall cost of the process and the unavoidable uncertainties of the screening procedure, three other solvents can be seen as promising: 1-MPZ, TEDA + PZ and DMPZ + PZ.

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