Preparation of Solid Superacid SO42-/ZnO-TiO2 and Its Action on Synthesis of Dimethyl Carbonate from Urea and Methanol

Abstract

<em><span>SO₄^2-/ZnO-TiO₂ catalyst was prepared by sulfating ZnO-TiO₂powders with H₂SO₄ solution. The catalyst was characterized by XRD, IR and Hammett indicator. The catalyst showed strong acidity(H₀ </span><span>≦</span><span>-16.0). The optimum conditions are found that the calcination temperature is 823K and the soaked consistency of H₂SO₄ is 1 mol/dm³. Then SO₄^2-/ZnO-TiO₂ was applied as the catalyst in the catalytic synthesis of dimethyl carbonate(DMC) from urea and methanol under <span>the optimum conditions and revealed higher catalytic activity. On condition that the reaction time is 6h,</span> the reaction temperature is 433K, the mass percent of the catalyst used in the reactants is 5wt.%, and the molar ratio of methanol to urea is 14, the yields of DMC can reach 27.9%.</span></em>