The production of several oxygenated derivatives of limonene was carried out by using orange oil and molecular oxygen as the sole initial reactants under solvent-free conditions. Palladium-copper supported on carbon and hydrotalcite-like compounds displayed good catalytic properties to accelerate autoxidation reactions of limonene yielding a mixture of the different oxygenated derivatives, mainly 1,2-and 8,9-epoxylimonene, 1,2,8,9-diepoxylimonene, carveol and carvone. Palladium supported on copper-magnesium-aluminium hydrotalcite displayed the best properties due to its higher catalytic activity and lifetime. The pelletized form of these catalysts can be easily recovered and reused. A reactor design combining recirculation and oxygen bubbling through a catalytic bed of the pelletized catalyst produced the highest reaction rate. Vacuum distillation of the final product mixture allowed easy separation of the 1,2/8,9-limonene epoxides. The other required compounds, mainly carveol and carvone, were not completely separated and remained together with the other oxygenated products, such as the di-epoxylimonene isomers.
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