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引入镍离子制备出新型固体超强酸Ni/SO42--SnO2,利用FT-IR、XRD、XPS、TG-DTA等测试手段对催化剂结构进行表征.FT-IR谱图显示,催化剂表面的硫酸根与金属以螯合双齿和桥式配位结合,形成了超强酸结构;XRD结果表明,样品表面主要显现出二氧化锡的四方晶型结构的二氧化锡,随着活化温度的提高,晶体结构渐趋完整,结合FT-IR结果表明可知,在973K,700℃时样品表面结合硫酸根已基本分解完毕;XPS结果表明,样品表面S仅存最高价态(+6),这是超强酸具有高的催化活性的首要条件;TG-DTA测得镍的引入有利于催化剂的热稳定性提高,可以较好地获得SO42-组份,使其高温分解流失趋势变得更缓和.以乙酸正丁酯的酯化反应为模型反应,通过正交实验和单因素实验得到Ni/SO42--SnO2的最佳制备条件,粗产品经GC-MS分析,乙酸正丁酯的含量为90.26%,实验结果表明引入一定浓度的镍离子能提高固体超强酸酯化活性.
A new type of solid superacid, Ni / SO42 - SnO2, was prepared by introducing Ni (superscript 2 +) ions and characterized by means of FT-IR, XRD, XPS and TG-DTA. The FT- XRD results showed that the surface of the sample mainly showed tin dioxide with tetragonal structure of tin dioxide. With the increase of the activation temperature, the crystal structure The result of FT-IR shows that the bound sulfate has been decomposed basically at 700 ℃ for 973K and 700 ℃. The results of XPS show that there is only the highest valence state (+6) on the surface of sample S, High catalytic activity of the first condition; the introduction of nickel measured by TG-DTA is conducive to the improvement of the thermal stability of the catalyst, the SO42- component can be better obtained, so that its tendency to pyrolysis decomposition becomes more moderate. With n-butyl acetate Esterification reaction of ester was the model reaction. The optimum preparation conditions of Ni / SO42 - SnO2 were obtained by orthogonal experiment and single factor experiment. The crude product was analyzed by GC-MS and the content of n-butyl acetate was 90.26% The results show that the introduction of a certain concentration of nickel ions can improve the solid superacid Esterification activity.