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为提高SO_4~(2-)/TiO_2固体超强酸的稳定性,向TiO_2载体中引入Ba制备成SO_4~(2-)/Ba-TiO_2复合固体超强酸,并采用X-射线粉末衍射(XRD)、比表面积分析(BET)、傅里叶变换红外光谱(FT-IR)、程序升温吸附氨脱附(NH3-TPD)等表征方法对其比表面积、晶相、硫质量分数、酸强度等进行分析。结果表明,Ba与TiO_2间会形成Ba Ti O3相,导致SO_4~(2-)/Ba-TiO_2固体超强酸的孔结构发生一定程度的坍塌;另外,FT-IR分析结果显示,在SO_4~(2-)/Ba-TiO_2固体超强酸中出现新的SO基团振动,说明形成了新的酸中心结构;而NH3-TPD结果表明,引入Ba并没有改变固体超强酸的酸强度和酸量。乙酸-正丁醇酯化反应结果显示,在103℃、酸醇摩尔比1∶1、催化剂用量0.5 g条件下,SO_4~(2-)/Ba-TiO_2的正丁醇转化率略低于SO_4~(2-)/TiO_2;但经过水预处理后,SO_4~(2-)/Ba-TiO_2呈现较高的正丁醇转化率,说明引入Ba在一定程度上提高了固体超强酸的稳定性。研究结果可为固体超强酸的工业化应用提供技术基础。
In order to improve the stability of SO_4 ~ (2 -) / TiO_2 solid superacid, the solid superacid SO_4 ~ (2 -) / Ba - TiO_2 was prepared by introducing Ba into TiO_2 support and characterized by X - ray powder diffraction , Surface area analysis (BET), Fourier transform infrared spectroscopy (FT-IR) and temperature programmed adsorption ammonia desorption (NH3-TPD) were used to characterize the surface area, analysis. The results show that the Ba Ti O3 phase is formed between Ba and TiO 2, resulting in the collapse of the pore structure of SO 4 2- / Ba-TiO 2 solid superacid. In addition, FT- 2 -) / Ba-TiO_2 solid superacid shows that a new acid center structure is formed. The results of NH3-TPD show that the addition of Ba does not change the acid strength and acidity of the solid superacid the amount. The results of esterification with acetic acid and n-butanol showed that the n-butanol conversion of SO 4 2- / Ba-TiO 2 was slightly lower than that of SO 4 at 103 ℃ with molar ratio of alcohol to alcohol 1: 0.5 and catalyst dosage 0.5 g ~ (2 -) / TiO_2. However, SO_4 ~ (2 -) / Ba-TiO_2 showed a higher n-butanol conversion after pretreatment with water, indicating that the introduction of Ba improves the stability of the solid superacid to a certain extent . The results provide a solid technical basis for the industrial application of solid superacid.