Synergy between electron donor and steric hindrance in Alkylated-Piperazine absorbents for efficient CO₂ capture

Piperazine (PZ) and its derivatives are currently regarded as novel amine absorbents for efficient CO₂ capture. However, the in-depth investigation of CO₂ capture and understanding of the structure–activity relationship in PZ-based absorbents are still lacking. In this study, we conducted a systematic investigation of CO₂ capture within the alkylated PZ-based absorbents. The results demonstrated that the increased alkylation degree can promote CO₂ absorption by enhancing the electron donor effect of the secondary amine group in PZ. In addition, the incorporated alkyl group in PZ-based absorbent improves the CO₂ desorption process by enhancing the steric hindrance effect. Particularly, the synergy between electron donor and steric hindrance effects in isopropyl alkylated-PZ (IPPZ) enables it to present enhanced cyclic capacity and remarkably low regeneration energy consumption (2.36 GJ·t⁻¹ CO₂) for CO₂ capture. The present study makes a valuable contribution towards the future design and development of highly efficient absorbents for CO₂ capture.