Effect of flow rate of a biphasic reaction mixture on limonene hydrogenation in high pressure CO₂

In this work the effect of the overall flow rate of the biphasic reaction mixture on hydrogenation distribution products is reported. As it was already presented by us, the reaction rate strongly correlates with the phase equilibrium existing in the system. On the other hand, carbon dioxide is nonreactive; nevertheless by its presence it changes the energy balance. The catalytic performance in four kinds of overall flow rate conditions (1.3, 3.3, 5.3, and 7.3 mL/min) was compared under fixed hydrogen (2.5 MPa) and total pressure (12.5 MPa). The appearance of isomers of limonene and partially hydrogenated products significantly rely upon the flow rate used in the reaction. The 1% Pd SCN catalyst used in the reaction gave the final products trans- and cis - p-menthane in a 2/3 to 1/3 molar ratio.