Carbon dioxide capture and regeneration with amine/alcohol/water blends

• Specific solvent loss was used as an indicator of regeneration energy penalty.
• The capture performances of solvents of amines were benchmarked against MEA.
• Low boiling solvents can be used to reduce regeneration energy penalty.

Non-aqueous low boiling chemicals have been considered as potential solvents for amines in post-combustion carbon dioxide capture by chemical absorption. In this study, a set of simplified experiments was devised to evaluate the overall capture and regeneration performances of five absorbents, including a 7 m monoethanolamine solution, a piperazine/diethylenetriamine/water solution, a piperazine/diethylenetriamine/diethylene glycol/water blend, a piperazine/diethylenetriamine/methanol/water blend, and a piperazine/diethylenetriamine/methanol solution. Among the five absorbents, the blend that used methanol and water as the solvent achieved a high absorption efficiency, a high desorption efficiency, and a low regeneration energy penalty. In addition, this blend did not suffer the problems of piperazine crystal formation in absorbents at low temperatures or precipitation in carbon dioxide rich solutions. The results showed that low boiling solvents could be used to reduce the regeneration energy penalty, and that efficient regeneration at a low temperature was possible. Analysis indicated that the critical factor for evaluating regeneration energy penalty was the specific solvent loss, which was defined as the amount of accompanying solvent loss per unit of carbon dioxide removed during regeneration.