Production of p-Cymene from Crude Sulphate Turpentine with Commercial Zeolite Catalyst Using a Continuous Fixed Bed Reactor

摘要

Crude sulphate turpentine (CST), containing alpha-pinene, 3-carene, other terpene isomers, and organic sulphur compounds, was used as feedstock in the production of cymenes with commercial zeolite catalysts. The catalysts used were not sensitive to sulphur, and the desulphurisation step was not needed prior to cymene synthesis. The experiments were performed in a continuous fixed bed reactor. Promising results were obtained after initial optimization at temperatures close to 300 degrees C with faujasite Y zeolite under 5 bar N-2 pressure. Cymenes were produced with 54% yields from model compound alpha-pinene and with 28% yields from CST. The mechanistic route of the reaction can be divided into three steps: (1) ring opening, (2) rearrangement, and (3) dehydrogenation. The final step in the formation of p-cymene can occur via dehydrogenation or disproportion; here the effect of reaction conditions and catalyst plays a crucial role.