Structural and CO2 Capture Properties of Ethylenediamine-Modified HKUST-1 Metal-Organic Framework

Abstract

The high structural and compositional flexibility of metal-organic frameworks (MOFs) shows their great potential for CO2 capture and utilization in accordance with the environmental guidelines of low-carbon technology developments. HKUST-1 as one of the most intensively studied representatives of MOFs for such purposes excels because of its simplicity of production and high ability to tune its intrinsic properties by various functionalization processes. In the present work, ethylenediamine functionalization was performed for the first time in order to thoroughly investigate the amine sorption sites' impact on the CO2 capture performance of HKUST-1. The placement of ethylenediamine moieties on Cu2+ free-metal sites has been examined in detail and confirmed by using various spectroscopic techniques such as Fourier transform infrared spectroscopy, electron paramagnetic resonance, Raman, and Cu K-edge extended X-ray absorption fine structure/X-ray absorption near edge structure. N2 and CO2 sorption tests have proven that the functionalization reduces both the specific surface area and the CO2 sorption capacity, but on the other hand, it increases the binding energy by 85% (from-20.3 kJ/mol to-36.8 kJ/mol) and CO2/N2 selectivity at 0.15/0.85 bar by 100% and notably improves the kinetics of adsorption in comparison to the pristine HKUST-1 material.