Abstract:

A solid acid SO₄^2-/SnO₂-diatomite was prepared by aging of diatomite-Sn(OH)₄ sol at 70 ℃ for 12 h, drying for 12 h at 90 ℃, impregnating in 3.0 mol/L H₂SO₄ for 3 h, and calcinating at 550 ℃ for 3.5 h. The solid acid was characterized by using IR, XRD and TG methods. The sol of diatiomite Sn(OH)4 was prepared with 1∶3 mass ratio of SnCl₄·5H₂Oto diatomite. Then isoamyl butyrate was synthesized from n-butyric acid and isoamyl alcohol in the presence of the composite solid acid as the catalyst. Effects of catalyst dosage, molar ratio of isoamyl alcohol to n-butyric acid, reaction time, and type of water entrainer on the yield of isoamyl butyrate（IAB） were examed. Under the optimized reaction conditions, n(isoamyl alcohol)∶n(n-butyric acid)=1.4∶1, reaction time in 70 min, benzene 10 mL, and the mass fraction of catalyst in total mass of reactants 2.5%, the yield of IAB was 97.7%. Compared with multicomposite solid acid and SO₄^2-/clay, the prepared catalyst possesses advantages of low cost, high activity, facile preparation and easy separation from the reaction system. It can be reused to a certain extent.

Key words: solid acid, diatomite, isoamyl butyrate, catalysis, synthesis