Studies On Preparation & Structure Of Mesoporous Solid Superacid SO₄～(2-)/XC And Synthesis Of N-Butyl Salicylate Over SO₄～(2-)/XC

Mesoporous Solid Superacids SO42-/XC(X-Al, Zr, SiZr, C-montmorillonite, rectorite) had been prepared and used as new catalysts in the synthesis of n-butyl salicylate. Various techniques, such as Hammett indicator, NH3-TPD, Py-IR, XRD, BET, TG, DTA and IR, had been used to characterize samples. On the basis of characterization, the reaction condition for preparation n-butyl salicylate, properties and structure of pillared clays had been investigated. The results showed that:The proper preparation conditions of catalysts SO42-/XC followed: SiZr was pillaring agent, accelerant was (NH4)2SO4, m(SO42-)/m(clay) was 30%, the temperature of calcination was 500癈, and n(SiZr)/m(clay) was 3.5mmol/g. Catalysts SO42-/SiZrC exhibited high catalytic activity and good catalytic stability in the synthesis of n-butyl salicylate. For example, the conversion of acid amounted to 88.22% over catalyst SO42-/SiZrM, and 86.85% over catalyst SO42-/SiZrR, the catalytic selectivity amounted to 99.9% and 99.5%, the conversion of acid only decreased by 5.33% and 1.98% after five times continuous reaction.Hammett indicator, NH3-TPD and Py-IR measurements indicated that catalysts SO42-/ZrC(500℃) and SO42-/SiZrC(500℃) were superacids. The type of superacid belonged to Lewis acid center, and also was the activity center of esterfication. XRD and BET measurements indicated that the pillaring agents fixed in the interlayer region of clays by chemical bond, and also increased basal spacing and surface area. When the calcination temperature increased, the basal spacing and surface area declined. After cross-linked, the scope of PILC aperture was narrow, especially, the aperture of catalyst SO42-/SiZrR(100℃) was around 2.3nm, and it was part of Mesoporous Materials. The dosage of SO42- was increased, the basal spacing and surface area declined. The basal spacing of SO42-/XR was higher than that of SO42-/XM, while surface area took on a contrary order. PILC SO42-/SiZrC had bigger basal spacing and largerer surface than SO42-/AlC and SO42-/ZrC. TG and DTA measurements indicated that the PILC had a good increase in the thermal stability. IR measurements indicated that the structure of organic sulfate appeared when catalystsSO42-/XR were calcinated at 500 ℃.The proper reaction conditions for the preparation of n-butyl salicylate over catalysts SO42-/XC were as follows: n(salicylic acid):n(n-butanol)=l:1.65, w(SO42-/XC) was 6.5%, the reaction time was 6h, and the reaction temperature was 120~135℃. Under these reaction conditions, the conversion of acid amounted to 88.22% over catalyst SO42-/SiZrM(500℃), and 86.85% over catalyst SO42-/SiZrR(500 ℃).