Liquid phase hydrogenation of dementholized peppermint oil on Pt/Al2O3 catalysts. Part I: A study of catalyst performance

J.C. YORI; D.L. MANUALE; A.J. MARCHI; J.M. GRAU

APPLIED CATALYSIS A-GENERAL

Elsevier Sci. B.V.

Lugar: Amsterdam; Año: 2004 vol. 275 p. 221 - 226

0926-860X

            The present work studies the catalytic hydrogenation of the (-)-menthone fraction existing in a dementholized peppermint oil, subproduct of the low-temperature crystallization process of the Arvensis peppermint oil.  The aim is to obtain a liquid menthol composition for commercial use that replacing the crystal form.  Pt/Al2O3 catalysts with different metal content (1 and 4%Pt) were used and the effect of several operating variables is analyzed: H2 pressure, reaction temperature, and reactant mass/catalyst mass ratio. Total conversion values ((-)-menthone + (+)-isomenthone) in the order of 95% on the fresh catalyst after 4 h on stream were obtained for 4%Pt/Al2O3. These conversion values decrease when the catalyst is reused, which is indicative of deactivation. When the Pt content is reduced, the total conversion values fall drastically. The (-)-menthone to (-)-menthol selectivity values are higher than 90% in every case. Keywords:            Pt supported on alumina, (-)-menthone catalytic hydrogenation, (-)-menthol isomers selectivity,  Fine Chemistry, Sustainable processes.