Inducing efficient proton transfer through Fe/Ni@COF to promote amine-based solvent regeneration for achieving low-cost capture of CO2 from industrial flue gas

Abstract

Catalytic amine-based solvent regeneration with solid acid is a feasible option for reducing energy consumption of CO2 capture, but facing crucial challenges on designing material structures and understanding reaction mechanisms. Herein, we cover the nanoscale NiFe2O4 cluster with covalent organic frameworks (COFs), to prepare solid acid catalysts. The pristine chemical bonds of Ni(Fe)-O and Ni(Fe)-Ni(Fe) are substituted by Ni(Fe)-N and Ni(Fe)-N-Ni(Fe) by targeting the anchoring of NiFe2O4 cluster over COFs. The created coordination state stimulates the production of Brønsted acid sites. The obtained nanomaterials achieve a considerable improvement in CO2 desorption of up to 290.1 mmol/(min·g) at 88 °C for spent monoethanolamine (MEA) solvent, representing a substantial increase of 540% relative to traditional thermal desorption. Consequently, the energy consumption of MEA generation is reduced by approximately 58%. Intermediate species (HCO3−, CO32−, and RNHCOO−) and reaction pathways are established by combining operando Raman spectroscopy and ex situ 13C NMR spectrum measurements. Theoretical calculations are performed to clarify the transformation mechanism of the acid sites around Ni/Fe atoms and its intrinsic role in the adsorption equilibrium of solvent regeneration.