CO2 capture and adsorption kinetic study of amine-modified MIL-101 (Cr)

Abstract

MIL-101 (Cr) was synthesized by a hydrothermal method and used as support to prepare a series of polyethylenimine (PEI) incorporated MIL-101 (Cr) by wet impregnation method. All characterization results revealed that the structure of MIL-101 (Cr) was well-maintained by the incorporation of polyethylenimine and confirmed the presence of PEI within MIL-101 (Cr). The CO2 adsorption studies were carried out in a fixed bed reactor from 30 to 90 °C, 1 bar. The adsorption of CO2 has been increased by the incorporation of PEI. It was due to the chemical interaction between the NH2 and CO2 groups to form a carbamate. The high CO2 adsorption capacity 3.81 mmol g−1 was shown by 70 wt% PEI loaded MIL-101 (Cr) at 75 °C, 1 bar, because of more number of NH2 groups and a high number of CO2 molecules diffusion. Its adsorption capacity was 4.7 times higher than the adsorption capacity of MIL-101 (Cr) (0.80 mmol g−1). Moreover, in moisture condition, CO2 adsorption capacity was increased to 4.4 mmol g−1 by the formation of ammonium bicarbonate and showed good adsorption stability throughout each adsorption-desorption cycle. The Avrami adsorption kinetic model was well fitted with experimental breakthrough CO2 adsorption data of MIL-101 (Cr)-PEI-70. It suggested that the adsorption of CO2 on PEI incorporated material was chemical adsorption.