A metal–organic framework MIL-101 doped with metal nanoparticles (Ni & Cu) and its effect on CO2 adsorption properties

Abstract

In this work, MIL-101-Cu and MIL-101-Ni were successfully synthesized via a microwave irradiation technique to enhance the adsorption capacity and adsorbent cyclability. The prepared adsorbents were characterized by various techniques such as XRD, FE-SEM, EDS, ICP, TEM and BET. TEM images clearly demonstrated that Cu and Ni NPs of 3–7 nm and 2–4 nm, respectively, were incorporated within the pores of the MIL-101 adsorbent. The CO₂ adsorption capacity was measured by a volumetric method. The equilibrium CO₂ adsorption capacities were measured as 9.7, 10.6, 11.8 and 12.4 mmol g⁻¹ for the parent MIL-101, activated MIL-101, MIL-101-Cu and MIL-101-Ni adsorbents, respectively at 7.1 bar and 298.2 K. The initial isosteric heats of CO₂ adsorption on the above mentioned adsorbents were estimated to be 22, 27, 31 and 38 kJ mol⁻¹, respectively. Successive adsorption–desorption cycles were conducted to explore the cyclability of the adsorbents. The results confirmed that the adsorption capacity remained constant after 100 cycles. The equilibrium experimental data were well-fitted with a Freundlich isotherm model.