Title: Effect of silica modification on the shape selective adsorption performance of HZSM-5
Abstract: The HZSM-5molecular sieve adsorbent was modified using polysiloxane as modifier and were characterized by means of X-ray diffraction(XRD),NH3-TPD,Surface Area and pore size analysis and thermogravimetric analysis(TGA).The effects of silicon deposition degree,liquid phase adsorption and gas phase adsorption process conditions on the shape-selective adsorption performance were investigated using liquid phase adsorption and gas phase adsorption.It was concluded that with the increase of deposited silica,the mesopore volune reduced,the micropore volume hardly changed and the crystal structure of adsorbents have not changed after the fourth deposition.Meanwhile the average adsorption capacities decrease while the selectivy of p-xylene increased;on the other hand,the p-xylene selectivity of the gas phase thermal desorption was higher than that of liquid phase desorption,and the shape selectivity of dichloromethane as desorption solution is higher than that of tolune and cyclohexane.Adsorption gravimetric test results show that the average adsorption capacity of Si/ZSM-5(0),Si/ZSM-5(2)and Si/ZSM-5(4)were 102.1,82.12 and 71.84mg/g and the diffusion rate of xylene mixture decreases with the increase of deposited silica.
Publication Year: 2015
Publication Date: 2015-01-01
Language: en
Type: article
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