Abstract: The hydration of α-pinene to α-terpineol was studied using SO₄^2-/Zr-MCM-41 mesoporous molecular sieves as catalyst in supercritical carbon dioxide (SCCD) for the first time. The reaction results showed that SO₄^2-/Zr-MCM-41 was of better selectivity to the α-terpineol in SCCD than in conventional conditions, and was of similar catalytic activity in SCCD as in conventional conditions. The effects of preparing conditions of catalysts and the reaction conditions on the reaction results in SCCD were examined and the optimum conditions were obtained as follows:mass ratio of chloroacetic acid: turpentine: water 1:1:3,dosage of catalyst 7.5% of turpentine (mass),mass ratio of Si/Zr 1:0.05, reaction temperature 60℃ of 8h. Under the optimum conditions, the conversion of pinene is 94%, and the selectivity to terpineol can reach 88%.

Key words: supercritical carbon dioxide, hydration reaction, turpentine, acid catalysis