SYNTHESIS OF LIQUID MENTHOL BY HYDROGENATION OF DEMENTHOLIZED PEPPERMINT OIL OVER Ni CATALYSTS

DÉBORA L. MANUALE; CAROLINA BETTI; ALBERTO J. MARCHI; JUAN CARLOS YORI; EVA ROMEO

QUíMICA NOVA

SOC BRASILEIRA QUIMICA

Año: 2010 vol. 33 p. 1231 - 1234

0100-4042

Hydrogenation of (-)-menthone and (+)-isomenthone was studied at 2.7 MPa and 100 ºC. The objective was to produce a liquid menthol mixture rich in (-)-menthol from dementholized peppermint oil. Ni-based catalysts were tested and compared for this reaction: a) 6 and 12% Ni dispersed into a nonstoichiometric magnesium aluminate (Ni-Mg-Al) with spinel structure; b) Ni-Raney catalyst. Both types of catalysts were active for (-)-menthone and (+)-isomenthone hydrogenation. Lower conversion but higher selectivity to (-)-menthol was obtained with Ni-Mg-Al catalysts. However, they rapidly lost their activity. Instead Ni-Raney catalysts kept its original activity even after several hydrogenation runs.