The isomerization of S-carvone over the natural clinoptilolite as the catalyst: the influence of reaction time, temperature and catalyst content

This work describes the isomerization of S-carvone using a natural zeolite—clinoptilolite as the catalyst. The isomerization of S-carvone was carried out at the catalyst content in the reaction mixture from 5 to 15 wt%, in a temperature range of 190–210 °C and for the reaction time from 60 to 300 min. The main product of the isomerization of S-carvone was aromatic alcohol with many practical applications—carvacrol. The use of the most favorable reaction conditions (the reaction time of 3 h, the temperature of 210 °C and the catalyst content 15 wt%) allowed to obtain this compound with high yield amounted to about 90 mol%. The S-carvone isomerization is an example of environmentally friendly process because it does not use any solvents, S-carvone can be separated from cheap cumin waste (renewable biomass) and a cheap zeolite of natural origin—clinoptilolite can be is used as the catalyst. Graphic abstract