p-Cymene production from orange peel oil using some metal catalyst in supercritical alcohols

- p-Cymene was produced mainly using Pd/Al2O3 and Pt/Al2O3, however, Ni/Al2O3 as catalyst did not show catalytic activity during orange peel oil.
- p-Cymene selectivity of Pd/Al2O3 was much better compared with Pt/Al2O3.
- 2-Propanol as solvent in supercritical conditions was effective over Pt/Al2O3.
- p-Cymene was produced mainly using Pd/Al2O3 and Pt/Al2O3, however, Ni/Al2O3 as catalyst did not show catalytic activity during orange peel oil.

In this study, orange peel oil which had been produced by cold press technique was processed. The catalytic reaction of limonene composed of 90-95% of the orange peel oil carried out in different supercritical alcohols, and it was obtained the compound p-cymene mainly. The experiments processed in a packed bed reactor using Pt/Al2O3, Ni/Al2O3 and Pd/Al2O3 catalysts in over supercritical conditions of ethanol and 2-propanol. Experiments of reaction time, temperature and pressure scanning were carried out in the ranges of 10-50 s, 245-340 °C and 6.5-12.5 MPa, respectively. It was observed that Ni/Al2O3 was ineffective to the conversion of limonene. However, when Pd/Al2O3 and Pt/Al2O3 catalysts were used, p-cymene was produced mainly. Especially, when Pd/Al2O3 catalyst was used, it was detected that limonene converted completely and obtained p-cymene in yield of 80%. Furthermore, p-cymene selectivity of Pd/Al2O3 was much better compared with Pt/Al2O3.

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