The heterogeneity of adsorption sites and adsorption kinetics of n-hexane on a chromium terephthalate-based metal–organic framework MIL-101(Cr) were studied by gravimetric method and temperature-programmed desorption...The heterogeneity of adsorption sites and adsorption kinetics of n-hexane on a chromium terephthalate-based metal–organic framework MIL-101(Cr) were studied by gravimetric method and temperature-programmed desorption(TPD) experiments. The MIL-101 crystals were synthesized by microwave irradiation method. The adsorption isotherms and kinetic curves of n-hexane on the MIL-101 were measured. Desorption activation energies of n-hexane from the MIL-101 were estimated by TPD experiments. The results showed that equilibrium amount of n-hexane adsorbed on the MIL-101 was up to 5.62 mmol·g-1at 298 K and 1.6 × 104 Pa, much higher than that of some activated carbons, zeolites and so on. The isotherms of n-hexane on the MIL-101 could be well fitted with Langmuir–Freundlich model. TPD spectra exhibit two types of adsorption sites on the MIL-101 with desorption activation energies of 39.41 and 86.69 kJ·mol-1. It reflects the surface energy heterogeneity on the MIL-101 frameworks for n-hexane adsorption. The diffusion coefficients of n-hexane are in the range of(1.35–2.35) × 10-10cm2·s-1with adsorption activation energy of 16.33 kJ·mol^(-1).展开更多
基金Supported by the National Natural Science Foundation of China(21276092)the Research Foundation of State Key Lab of Subtropical Building Science of China(C713001z)+2 种基金the Science and Technology Research Foundation of Guangzhou City,China(200910814001)Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control(2011A060901011)the Fundamental Research Funds for the Central Universities(2013ZZ0060 and 2013ZM0056)
文摘The heterogeneity of adsorption sites and adsorption kinetics of n-hexane on a chromium terephthalate-based metal–organic framework MIL-101(Cr) were studied by gravimetric method and temperature-programmed desorption(TPD) experiments. The MIL-101 crystals were synthesized by microwave irradiation method. The adsorption isotherms and kinetic curves of n-hexane on the MIL-101 were measured. Desorption activation energies of n-hexane from the MIL-101 were estimated by TPD experiments. The results showed that equilibrium amount of n-hexane adsorbed on the MIL-101 was up to 5.62 mmol·g-1at 298 K and 1.6 × 104 Pa, much higher than that of some activated carbons, zeolites and so on. The isotherms of n-hexane on the MIL-101 could be well fitted with Langmuir–Freundlich model. TPD spectra exhibit two types of adsorption sites on the MIL-101 with desorption activation energies of 39.41 and 86.69 kJ·mol-1. It reflects the surface energy heterogeneity on the MIL-101 frameworks for n-hexane adsorption. The diffusion coefficients of n-hexane are in the range of(1.35–2.35) × 10-10cm2·s-1with adsorption activation energy of 16.33 kJ·mol^(-1).
