Abstract: With the purpose of establishing an application method, studies on the catalytic transformation of 3-carene were carried out. The results indicated that metal catalysts, especially the platinum, had excellent ability to promote the ring opening and dehydrogenation of three-membered ring in 3-carene. With platinum-catalysis, the selectivity of dehydrogenation product cymene exceeded 90% and the mass ratio of m-cymene to p-cymene was nearly 7:2. The ring opening and dehydrogenation of 3-carene could be similarly catalyzed by molecular sieves. However, with the rising of temperature, the dehydrogenation product p-cymene would further be cracked to aromatics like toluene. Molecular sieves ZSM-5 showed a prominent activity in promoting this reaction. On the basis of these results, a continuous process of preparation of toluene and m-cymene from 3-carene was established by using platinum and ZSM-5 as a kind of composite catalyst. The conversion rate of raw material was nearly 100% and the yield of all products was more than 85%. The yield and purity of one of the final products toluene were 25% and 99%, respectively. While m-cymene were 46% and 95%, respectively, with reaction conditions at the volume ratio of Pt/Al₂O₃ to ZSM-5 1:1 and 280℃.

Key words: 3-carene, catalytic transformation, metal catalyst, ZSM-5 molecular sieves, m-cymene