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

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.