The Transalkylation Of Diisopropylbenzen On The USY Zeolite

In this dissertation, the thermodynamic properties of the reaction system are studied based on the knowledge of thermodynamics.A series of USY zeolite catalysts were respectively modified by NH3, Mg and NH3-Mg. The USY samples before and after modification were characterized by XRD, BET, NH3-TPD, and NMR. The catalytic performance of the USY samples was investigated on the iso-thermo fixed reactor. The results showed that NH3 modification can maintain the USY zeolite framework structure, at the same time, effectively improve the distortion environment of the four-coordinated framework aluminum in which the crystallinity of the catalyst was increased. And with the growth of NH3 modification time, USY zeolite mesoporous volume was increased, pore size distribution was widened. Furthermore, the sample with NH3 modified for 6h significantly increased the acidity of zeolite and the conversion of diisopropylbenzene increased by 10%, the selectivity of isopropylbenzene was increased from 80.12% to 86.14%. By incipient impregnation method, USY zeolite was modified by Mg2+. The quantity of Mg loaded on the zeolite is 0.15%,0.5%,1% of the Mg2+. The catalyst evaluation results show that the optimal modified concentration of magnesium ion is 0.15%-0.5%. NH3 and Mg2+ modification, the catalyst evaluation results showed that the conversion of diisopropylbenzne was increased to 86.89%, and the life time of the catalyst in the study time (72 hours) showed activation.Using single-factor test, in a wide range of operating temperature (140℃-200℃), benzene and diisopropyl benzene molar ratio (5:1-11:1), the change of the conversion and selectivity of the transalkylation reaction was investigated. The results show that:as the temperature increased, the conversion of diisopropylbenzene and the content of n-propylbenzene increased, but the selectivity of isopropylbenzene decreased. Improving the molar ratio of benzene/diisopropylbenzene is conducive to enhance the conversion and selectivity, but when the molar ratio is more than 9, the effect of molar ratio on the conversion and selectivity significantly decreased. When the raw material contains triisopropylbenzene, the conversion of diisopropylbenzene decreased, as the temperature incresed, the influence of triisopropylbenzene gradually decreased.