Solid super acidic SO₄^2-/ SnO₂-Al₂O₃ catalyst prepared through low-temperature aging

Solid super acidic SO₄^2-/ SnO₂-Al₂O₃ catalyst was prepared through low-temperature aging and impregnation. Effects of preparation conditions on the catalyst activity in synthesis of butyl glycol acetate(BGA) from 2-butoxyethanol and acetic acid, as a probe reaction, were investigated. The optimal conditions for preparation of SO₄^2-/ SnO₂-Al₂O₃ catalyst were n(Sn) : n( Al) 9, aging temperature 0°C, aging time 24 h, concentration of impregnating solution(sulfuric acid) 1.0 mol/L, impregnating solution dosage 15 mL/g (based on mass of SnO₂-Al₂O₃ support) and calcination temperature 500°C. Yield of BGA over the SO₄^2-/ SnO₂-Al₂O₃ catalyst could reach 97.8% under the reaction conditions; n(2-butoxyethanol) : n(acetic acid) 1.2 : 1, m(catalyst) : m(reactants) 0.024, m(cyclohexane) : m(reactants) 0.3 and reaction time 4 h. Catalytic activity of the SO₄^2-/ SnO₂-Al₂O₃ catalyst reduced to 88. 6% after being reused five times. Introduction of alumina prolonged the life of the SO₄^2-/SnO₂ type solid super acidic catalyst. Activity of the deactivated SO₄^2-/ SnO₂-Al₂O₃ catalyst could be recovered after calcination.