Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (02): 142-146.doi: 10.3866/PKU.WHXB20020210

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Studies on Acidity and Basicity and Adsorption of Modified Y Zeolites

Zhou Ling-Ping;Deng Liang;Kou Yuan;Li Xuan-Wen   

  1. College of Chemistry & Molecular Engineering, Peking University,Beijing 100871
  • Received:2001-08-13 Revised:2001-10-30 Published:2002-02-15
  • Contact: Zhou Ling-Ping E-mail:zhou_ling_ping@hotmail.com

Abstract: The acidity and basicity of alkali cation exchanged Y zeolites were investigated systematically using pyridine and pyrrole as the TPD and IR spectroscopic probe respectively. It was found that the overall Lewis basicity in the modified Y zeolites increased and the Lewis acidity in the modified Y zeolites decreased as the cation was exchanged from LiY to CsY in the alkali cation series. The adsorption of benzene, toluene and ethylbenzene on Y zeolites modified by alkali cations were also studied comparatively by IR spectroscopy and TPD. The following results were obtained: (1)The adsorption of pyridine on modified Y zeolites could also be used to characterize the acidity and basicity of alkali cation exchanged Y zeolites; (2) The C-H stretching frequencies of aromatic ring, of CH3 on the side-chain of toluene, and of -CH2- on the side-chain of ethylbenzene shifted towards lower wavenumber as the cation was exchanged from LiY to CsY; (3)The adsorption strength and the amount of sorbed aromatics on modified Y zeolites were related to the basicity of alkali cation exchanged Y zeolites.

Key words: Modified Y zeolites, TPD, FTIR, Surface acidity and basicity, Aromatic hydrocarbon adsorption