Abstract: Immobilized AlCl₃ catalysts supported on γ-Al₂O₃ and SiO₂ were prepared by a two-step vapor method and their catalytic activities were evaluated by the liquid phase isomerization of α-pinene for the first time. The results showed that the immobilized AlCl₃ catalyst gave excellent catalytic performance for the isomerization of α-pinene. The AlCl₃/SiO₂ catalyst gave 98.4% conversion of α-pinene and 93.7% selectivity for the main products such as camphene, limonene, and terpinolene at a reaction temperature of 40 °C. The AlCl₃/γ-Al₂O₃ catalyst gave much higher activity, 95.5% conversion of α-pinene and 94.4% selectivity for the main products even at temperatures as low as 30 °C. The excellent catalytic performance of the immobilized AlCl₃ catalysts is due to their strong acidity.

Key words: immobilization, aluminum chloride, α-pinene, isomerization, silica, alumina