【作者】 张凤媛；

【导师】 严世强；

【作者基本信息】 兰州大学 ， 应用化学， 2006， 硕士

【摘要】 随着绿色化学的倡导,“绿色催化”这一全新的概念摆在了我们的面前。固体超强酸具有高活性、高选择性、低腐蚀、低污染以及容易与反应物分离、可重复利用、热稳定性好等特点,符合绿色催化的要求,因而对固体超强酸的研究成为当前的热点之一。 本文论述了固体超强酸催化剂的研究进展及其在酯化反应中的应用。采用溶胶一凝胶法制备SO₄^2-/TiO₂-SiO₂固体超强酸催化剂,考察它在乙酸甲酯酯化反应中的催化活性。用正交试验法对催化剂的制备条件进行优化,并对催化剂的酸强度、酸结构进行了系统的研究。具体工作分为三部分进行: 1)催化剂制备及催化活性考察。用正交试验分析得出制备SO₄^2-/TiO₂-SiO₂固体超强酸催化剂的最佳条件为:钛酸丁酯（TBT）含量为A₁（0.5g）,硫酸含量为B₃（1.5m1）,焙烧温度为C₁（400℃）,钛酸丁酯加入温度为D₂（20℃）。其中焙烧温度对催化剂的催化活性影响最大。 2)采用Hammett指示剂法、TG和IR分析手段对催化剂物性进行表征。结果表明:SO₄^2-/ZiO₂-SiO₂催化剂的酸强度最大达-12.70。SO₄^2-/TiO₂-SiO₂固体超强酸的酸中心模型是螫合式双配位。 3)对催化剂的失活机理进行讨论,结果表明用于乙酸甲酯酯化反应的SO₄^2-/TiO₂-SiO₂固体超强酸催化剂失活的主要原因是催化剂表面积碳和SO₄^2-流失。更多还原

【Abstract】 With Green Chemistry being advocated, the brand-new concept of green catalyst has been brought forward recently. Solid superacid has many advantages such as high activity, well selectivity, and no corrosiveness, no pollution, and liability to be separated from the reaction material. It is a green industrial catalyst that is helpful to recycling and possesses wide prospect of application. Thus, research on solid superacid has drawn more and more attention in industrial catalyst field.In this paper, we recounted the recent development of solid supeeracids and their appliance in esterification. The SO₄^2-/TiO₂-SiO₂ solid superacid catalyst was prepared by sol-gel method;its catalytic activity was investigated to synthesis of methyl acetate. The reactive condition of catalyst was optimized by orthogonal method. The acid strength and structures of solid superacid catalyst was research. The whole process is divided into three parts which are as follow:1) The examination of catalytic preparation and property. By orthogonal experiments, we have educed SO₄^2-/TiO₂-SiO₂ catalytic best preparative conditions: the amount of tetrabutyl titanate is A₁ （0.5g）, the amount of vitriol is B₃ （1.5ml）, the temperature of calcine is C₁ （400 ℃）, the temperature of dripping tetrabutyl titanate is D₂ （20℃） . The temperature of calcine is the maximal influencing factor for catalytic activity of catalysts.2) We have investigated catalytic physical properties by song analytical methods, such as IR, TG and Hammett indicator. Then we have drawn a conclusion: the maximal acid strength of SO₄^2-/TiO₂-SiO₂ solid superacid catalyst is -12.70. The acid centre mode of SO₄^2-/TiO₂-SiO₂ is chelate structure.3) By discussing the mechanism of catalytic losing activity. We have concluded that the main losing activity reason of SO₄^2-/TiO₂-SiO₂ solid superacid catalysts used in synthesis of methyl acetate is the accumulated carbon of catalytic surface and the loss of SO₄^2-.更多还原