Catalytic Isomerization of [alpha]-Pinene Epoxide Over a Natural Zeolite

• Published in: Catalysis letters Vol. 150; no. 11; pp. 3132 - 3148
• Main Authors: Sánchez-Velandia, Julián E, Gelves, John F, Márquez, Marco A, Dorkis, Ludovic, Villa, Aída-Luz
• Format: Journal Article
• Language: English
• Published: Springer 01-11-2020
• Subjects: Aldehydes; Isomerization; Zeolites
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-020-03225-9

Isomerization of [alpha]-pinene epoxide was carried out over a Colombian natural zeolite as potential geocatalyst with heulandite, chabazite and clipnotilolite as main crystallographic phases; the heulandite was identified as the active phase. Over synthetic zeolites, isomerization of [alpha]-pinene epoxide depended on Si/Al ratio, unit cell and the kind of structure. The best solvent was toluene and not isomerization activity was observed in presence of solvents with carboxyl groups. Complete [alpha]-pinene epoxide conversion and 45% selectivity to campholenic aldehyde were obtained at 70 °C, with fencholenic aldehyde, carveol, and p-cymene as main by-products. Decrease of activity of natural zeolite was associated with loss of acid sites. A reaction mechanism based on experimental and computational data was proposed including adsorption of [alpha]-pinene epoxide on Fe or Al sites of the natural zeolite; a reaction rate constant of 4.02 x 10.sup.-4 mol g.sup.-1 min.sup.-1 was estimated from a pseudo homogeneous kinetic model.