Isomerization of ?-pinene over calcined natural zeolites

In this work, isomerization reaction of ?-pinene was studied over several heat-treated natural zeolite catalysts, rich in clinoptilolite, from Balykesir-Bigadic region in Turkey in a batch slurry reactor under nitrogen atmosphere. Zeolite samples were calcined at different temperatures such as 300, 450 and 600°C. All catalysts were tested in the isomerization reaction of ?-pinene and were characterised by nitrogen adsorption experiments, IR, and XRD measurements. Acidity strength and the distribution of Lewis and Bronsted acid sites of the samples were determined. Selectivities to main reaction products, camphene and limonene, and reaction kinetics were investigated. Catalytic activity, that is total conversion of ?-pinene, of heat-treated samples decreased with increasing calcination temperatures. Selectivity to limonene is dependent on ?-pinene conversion at high conversion levels while the selectivity to camphene is not. The formation of heavy products increased with treatment temperature. It was seen that ?-pinene consumption could be described by a first-order kinetics. © 2004 Elsevier B.V. All rights reserved.National Council for Scientific Research: MISAG-120We thank Ilhami Taskiran for GC analysis and Mehmet Akçay for IR measurements. This study is a part of a project supported by the Turkish Scientific Research Council under Project MISAG-120. -