Isomerization and Dehydroaromatization of R(+)-Limonene Over the Ti-MCM-41 Catalyst: Effect of Temperature, Reaction Time and Catalyst Content on Product Yield

Abstract

This work describes research on the isomerization of R(+)-limonene over the Ti-MCM-41 catalyst. The studies showed that the Ti-MCM-41 catalyst is an active catalyst in the isomerization of R(+)-limonene. As a result of the isomerization of this compound, it is possible to obtain α-terpinene, γ-terpinene, terpinolene and p-cymene. Terpinolene is the main product of this process, and p-cymene is formed by the alpha-terpinene, gamma-terpinene and terpinolene dehydrogenation. The aforementioned products are of great practical importance. The most favorable reaction conditions leading to the obtaining of limonene isomerization products is the use of the catalyst in an amount of 15 wt% and the temperature of 160 °C. Depending on whether the desired products are the isomers of limonene (γ-terpinene, α-terpinene and terpinolene) or the product of their dehydroaromatization (β-cymene), it is possible to shorten or extend the reaction time. The method for the isomerization of limonene on the Ti-MCM-41 catalyst makes it possible to obtain a significant yield of both the limonene and p-cymene isomers. Longer reaction time is conducive to obtain larger quantities of other reaction products and less desirable products that constitute impurities (oxidized products and polymeric compounds).