Studies On The Preparation Of Solid Superacid SO₄^2-/M_xO_y And Synthesis Of Iso-amyl Acetate With The Catalyst

In view of the environment pollution problem existed in the catalytic synthesis of isoamyl acetate, the study of preparation and application on the solid superacid catalyst SO₄^2-/TiO₂ have been presented, and two kinds of performance improvement were carried out in order to improve reactivity of SO₄^2-/TiO₂.The correlation between catalytic structure and properties was investigated. All these strongly support the industrialization of isoamyl acetate synthesis catalyzed by solid super acid.SO₄^2-/TiO₂ solid acid catalyst was prepared from sol-gel method combined with Impregnation. The liquid phase esterfication of acetic acid with isoamylol was preformed to confirm the optimal conditions of preparation.The influence of different factors on the reaction was studied, and the optimum preparation conditions of the solid super acid were as follows:immersing concentration of H₂SO₄ 1.0mol/L, calcination temperature 500℃, and calcination time 3h. The technological conditions of isoamyl acetate were that the reaction temperature 110-130℃, the reaction time is 6h, n(acetic acid):n(isoamylol)= 1.4:1, w(catalyst)is 5% based on the mass of acetic acid, and the esterification ratio was over 93%.V-promoting SO₄^2-/TiO₂ (STV) solid super acid was prepared by introducting V on SO₄^2-/TiO₂ for performance improvement of SO₄^2-/TiO₂, and the optimum preparation conditions of the complex solid super acid were as follows: immersing concentration of NH₄VO₃ 0.010 mol/L and H₂SO₄ 1.0mol/L, calcination temperature 500℃, and calcination time 3 h.Under the optimum conditions, the esterification ratio was over 95%. It was carried on the performance evaluation of isoamyl acetate, which could meet the requirements for perfume of the GB6576-1996. The phase structure, the surface acidity and acid strengthdistribution, the state of surface SO₄^2- and the mechanism of stability were analyzed and characterized by XRD, Hammett indicator, IR and TG. The results showed that the introduction of the V delayed the crystallization of the matrix oxide, decreased particle's diameter.Both STV and ST were solid super acid and the introduction of the V has strengthened the acidity.SO₄^2- is conbined with metal ions of TiO₂ in chelating bidentate SO₄^2-.Solid super acid in the preparation of 500℃roasting temperature was the right choice, and the introduction of V enhanced solid super acid catalyst for the binding capacity of SO₄^2-, extended catalyst life, and improved the Catalyst stability. Different methods of regeneration condition of synthesized catalyst showed that the deactivation of STV catalyst wre resulted from the loss of SO₄^2- and the carbon deposition, and which could be reactivated by treating the used catalyst with calcinations to remove surface depostion with organic ingredient and supplement sulfur. The complex solid superacid catalyst SO₄^2-/TiO₂-ZrO₂-Fe₂O₃ was prepared by precipitation impregnation method for performance improvement of SO|₄^2-/TiO₂.The optimum preparation conditions of the complex solid super acid were as follows: n(Ti):n(Zr):n(Fe)=3:1:2, H₂SO4 0.75mol/L and calcination temperature 500℃. Under the optimum conditions, the esterification ratio was over 96%. Characterization of the structure and acid properties of solid superacid by XRD, IR and TG techniques and discussion about regeneration method came to the similar conclusions of STV.