[Cu3(BTC)2]-polyethyleneimine: an efficient MOF composite for effective CO2 separation

Abstract

Increased CO₂ concentration in the earth’s atmosphere results in global warming and has increased concerns towards the development of efficient strategies for carbon capture and storage. CO₂ separation from flue gas is one of the most challenging areas. Here, a Cu-BTC MOF and a series of polyethyleneimine (PEI) incorporated Cu-BTC composites (Cu-BTC–PEI) with different loading amounts of PEI have been developed for CO₂ separation. A significant increase in CO₂ adsorption capacity was observed with Cu-BTC–PEI adsorbents. Detailed characterization of the developed adsorbents was done using XRD, SEM, BET surface area and IR. The synthesized adsorbents show good CO₂/N₂ selectivity for a designed flue gas composition containing 15 vol% CO₂ and the remainder as N₂. 2.5 wt% PEI loaded Cu-BTC (Cu-BTC–PEI-2.5) has shown a CO₂ adsorption capacity of 0.83 mmol g⁻¹ at a pressure of 0.15 bar and 25 °C which is almost double that of Cu-BTC in similar conditions. But at an elevated pressure of 5 bar and 25 °C, 1 wt% PEI loaded Cu-BTC (Cu-BTC–PEI-1) performed even better with a CO₂ adsorption capacity of 10.57 mmol g⁻¹. Better adsorption capacity and selectivity for CO₂ was obtained with Cu-BTC–PEI composites and they are good aspirant adsorbents for CO₂ separation from flue gas.