Synthesis And Adsorption Property Of A Novel Iron-based Metal-organic Framework

MIL-100（Fe）, featured by its environmetal friendship and accessible partial unsaturatedmetal sites, is one of the most eye-catching nanomaterials among MOFs. The presentresearches concerning the product yield, the adsorption and desorption of carbonmonoxide,the hygroscopic property of MIL-100（Fe）are relatively insufficient, which restricts the furtherdevelopment of this material. In order to solve these problems, it is necessary to do thefollowing works.A new method of process improvement on the synthesis of MIL-100（Fe） was advanced.The optimalsynthesis time and temperature are120min and160℃respectively.By adding12mmol additive （Fe:BTC:H₂O:Additive:HNO₃=1:0.67:278:2:2.6）,the yield of MIL-100（Fe） canreach55.03%, and thisresult is more than20%higher than the yield of MIL-100（Fe）synthesized following traditional synthesizing process. The improving of yield helps to saveresource and energy as well as provide technical support for furthering application ofMIL-100（Fe）.Adsorption equilibrium and kinetics, TPD desorption and breakthrough property of COon the MIL-100（Fe） crystal was studied. Resultsshowed thatthe amount adsorbed of CO onthe MIL-100（Fe） was up to2.56mmol/g at298K and10bar. The isosteric adsorptionheatchanged slightly with the amounts adsorbed of CO, indicating the uniformity of surfacestructure and adsorption energy.The diffusivity coefficients of CO within MIL-100（Fe） crystalwas between1.1×10^-15and3.9×10^-15cm²/s. MIL-100（Fe） had two kinds of adsorption sites,with desorptionactivation energy53.38kJ/mol and109.5kJ/mol respectively; the workingadsorption amount of CO on MIL-100（Fe） was9.95mg/g，for5%（v/v） carbonmonoxidemixed gases.Adsorption equilibrium and kinetics, TPD desorption and breakthrough property of watervaporon the MIL-100（Fe） crystal was studied. The result indicated that the adsorptionisotherm of water vapor on MIL-100（Fe） was Type Ⅴ. The amount adsorbed of water vaporon MIL-100（Fe） was up to0.61g/g whenT=298K RH=90%.The diffusivity coefficients ofwater vapor was between2.735×10-16and5.603×10-16cm²/s within MIL-100（Fe） crystal,andactivation adsorption energy was38.41kJ/mol. Desorptionactivation energy was 60.53kJ/mol. The working adsorption amount of water vapor on MIL-100（Fe） was0.11g/g,for RH=40%mixed gases.Finally, adsoption property of CO/H₂O（g）mixed gases within MIL-100（Fe） fixed bed wasinvestigated. Results showed that competitive adsorption of water vapor was existed,decreased the working adsorption amount of carbonmonoxide on MIL-100（Fe） to9.11mg/g（0.325mmol/g）..