Liquid-phase isomerization of ?-pinene on a natural clinoptilolite

The liquid-phase isomerization of ?-pinene on a suspended powder (50-100 µm) of a natural clinoptilolite is studied. It is found that thermoevacuation at 500°C decreases the catalyst's activity and selectivity. The surface acidity decreases, whereas the surface concentration of Fe2+ ions increases. The reaction mechanism is proposed.