Synthesis Of Metal-organic Frameworks-mof-5 And Mil-101 And Their Adsorption/desorption Properties For VOCs

VOCs are a kind of environmental pollutant source which seriously threat human health and sustainable development of our society. Therefore, it is extremely urgent for us to effectively deal with VOCs. Adsorption technology is a technique which focuses on porous structured materials and is considered as one of the most potential technology for the air pollution treatment, so to develop new porous materials efficient to adsorb VOCs is the key point. This research mainly involves synthesis and characterization of MOF-5 and MIL-101, and measurements of their adsorption/desorption properties toward benzene and toluene. This study belongs to the fields of environmental engineering, chemical engineering and material engineering. It has important research significance and practical application background.The effects of synthesis condition on its physical properties of the MOF-5 crystals, including surface area and porous texture, were investigated. Results showed that the MOF-5 crystals whose particle sizes ranged from 20 to 60μm, surface area was up to 1022 m2/g and pore volume up to were obtained under the following conditions: synthesis temperature of 130℃, reaction time of 4 hours, the Zn2+/H2BDC molar ratio of 3, N, N-dimethylformamide as the solvent, certain purification and activating method.The effects of synthesis condition on its physical properties of the MIL-101 crystals including surface area, porous texture and so forth, were investigated. Results showed that high quality and purity MIL-101 crystals whose particle sizes ranged from 40-90 nm, surface area was up to 4443 m2/g and pore volume up to 1.89 cmwere obtained under the following conditions: synthesis temperature of 210℃, 1 hour's microwave radiation, certain Cr3+/H2BDC/HF/H2O molar ratio, certain purification and activating method.Benzene and toluene adsorption isotherms and kinetic curves on the MOF-5 and the MIL-101 particles were determined, and the diffusivity coefficients and adsorption activation energy of toluene on MIL-101 were estimated. Results showed that the amounts adsorbed of benzene and toluene on the MOF-5 and the MIL-101 were up to 16.3 mmol/g and 11.0 mmol/g respectively at 298 K and p/pB0 B= 0.5, which showed that MIL-101 has higher adsorption capacities of both benzene and toluene; and the adsorption activation energy of toluene on the MIL-101 was 10.9 kJ/mol, which was obviously lower than that on activated carbon.TPD spectrums of toluene on the MIL-101 were determined, and then the desorption activation energy of toluene was estimated. Results showed that the desorption activation energy of toluene on the MIL-101 was 28.0 kJ/mol, which was obviously lower than that on other conventional adsorbents.The results above indicated that, the MIL-101 material not only had high adsorption capacity and adsorption rate for toluene in comparison with conventional adsorbents, but also had easily toluene desorb from it. It is a promising material for VOCs adsorption.