Adsorption and Diffusion of Benzene on Chromium-Based Metal Organic Framework MIL-101 Synthesized by Microwave Irradiation

Adsorption equilibrium and diffusion of benzene on mesoporous chromium−terphthalate-based crystals (MIL-101) were experimentally studied by the gravimetric method in the pressure range up to 60.0 mbar. The MIL-101 crystals, whose sizes are about 100 nm, were synthesized by using microwave irradiation method. Adsorption isotherms and kinetic curves of benzene on the MIL-101 were measured experimentally. Results show that the maximum amount adsorbed of benzene on the synthesized MIL-101 was up to 16.5 mmol/g (or 176 wt %) at 288 K and 56.0 mbar. Diffusion coefficients of benzene within the MIL-101 were in the range of (4.25−4.76) × 10 −9 cm 2 /s in 288−318 K with a lower activation energy of 2.41 kJ/mol. Temperature programmed desorption (TPD) curves exhibited two separated peaks corresponding to two types of major adsorption sites for benzene adsorption on MIL-101. Consecutive cycles of adsorption−desorption experiment showed a fast desorption kinetics and high reversibility for benzene adsorption on MIL-101. The efficiency of benzene desorption from MIL-101 can reach 97%.