Acta Phys. -Chim. Sin. ›› 1995, Vol. 11 ›› Issue (03): 252-256.doi: 10.3866/PKU.WHXB19950313

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The Influence of Micro Structures of Silicalite and Rich-Silica ZSM-5 on Desorption Properties of p-xylene

Zeng Hong, Jiang Hui-Wen, Long Ying-Cai, Sun Yao-Jun, Wang Li-Ping, Wu Tai-Liu   

  1. Department of Chemistry,Fudan University,Shanghai 200433|Centre of Analysis and Measurement, Fudan University
  • Received:1993-11-15 Revised:1994-03-21 Published:1995-03-15
  • Contact: Long Ying-Cai


The structures of silicalite-1 and H、 Na form of ZSM-5 with various SiO2/Al2O3 ratios were characterized by powder XRD, 29Si MAS NMR, and the desorption process of р-xylene (p-x) on the zeolites was investigated by using TG/DTG/DTA. SiOH defects of ZSM-5 have no relation with the content of structural Al. Silicalite-1 possesses perfect framework structure without SiOH defects and structural Al. On a curve of TG/DTG/DTA, p-x adsorbed by silicalite completely desorbs in the range of 57-174℃ by two steps, accompanied with endothermal effect. While on the TG/DTG/DTA curves of H, Na-ZSM-5, there is a third adsorption step of p-x in the range of 180-600℃ with exothermic effect. Below 180℃ the number of desorbed p-x molecules is related to pore space, but over 180℃, it is related to SiOH and positive ion linking with the structural Al.

Key words: ZSM-5, Silicalite-1, SiOH defects, Desorption, 29Si MAS NMR, TG/DTG/DTA