Li Xuan-Wen

Relationship Between Catalytic Activity And Acid Strength Of Lahy Zeolites In Cumene Cracking And O-Xylene Isomerization

The surface acidity of a series of LaHY/LaNaHY, prepared by successive poisoning with NaOH, has been investigated in relation to their catalytic activities in cumene cracking and o-xylene isomerization. The results showed that the acid sites having acid strength H o ≤-3.0 were catalytically active for both reactions. A decrease in apparent activation energy with increased acid strength was observed. By using “regional analysis” the relationship between activity and acid strength was established and followed the Bronsted catalysis law approximately. In comparison with their activity in o-xylene isomerization, the activity of LaHY/LaNaHY zeolites in cumene cracking was much higher. The rate constants were 1–2 orders of magnitude higher and apparent activation energies much lower.