Biphasic hydrogenation of α-pinene in high-pressure carbon dioxide

Abstract

Results on the kinetics of hydrogenation of a-pinene in high-pressure carbon dioxide, using Pt/C (1%) catalysts, are presented. Experiments were performed at different carbon dioxide pressures, so that the reaction mixture in contact with the solid catalyst would either be biphasic (liquid + gas) or a single supercritical phase. The technique involved the use of a high-pressure view cell, which allows direct visual observation of the number of phases in the reactor. The hydrogenations in biphasic conditions, at lower carbon dioxide pressures, are completed faster than in supercritical conditions. The results indicate that the pinene adsorption to the metal in the catalyst is the rate-controlling step.

Heterogeneous Catalytic Hydrogenation Reactions in Continuous‐Flow Reactors

“…Nunes da Ponte and co-workers compared hydrogenation rates of apinene under biphasic conditions using 1 % Pt/C as a reduction catalyst. [159] The obtained results clearly show that hydrogenation under biphasic conditions can, in certain conditions, actually be as fast, or even faster, than in one supercritical phase. The same research group also carried out the selective hydrogenation of limonene and b-myrcene in highly pressurized carbon dioxide.…”

Continuous catalyst-free aromatization of γ-terpinene using air as an oxidant

“…Terpenes are obtained by fractional distillation of turpentine 1 and can be modified by catalytic methods 2 such as hydrogenation, [3][4][5] dehydrogenation, 6-14 rearrangement, [15][16][17] and oxidation reactions. Terpenes are obtained by fractional distillation of turpentine 1 and can be modified by catalytic methods 2 such as hydrogenation, [3][4][5] dehydrogenation, 6-14 rearrangement, [15][16][17] and oxidation reactions.…”

Notes on the Asymmetric Hydrogenation of Methyl Acetoacetate in Neoteric Solvents

“…Another possible explanation is the dilution effect. It is expected to be prevailing at higher pressures of CO 2 [55,56]. Experiments carried out at much lower pressures, it means at the level when virtually no expansion took place, did not point out on any contribution of diluting to the drop of the reaction rate.…”