焙烧温度对SO2-4/TiO2固体超强酸抗水稳定性的影响

通过水预处理方法对比研究了不同焙烧温度制备的SO2-4/TiO2固体超强酸的抗水稳定性,借助XRD、NH3-TPD、FT-IR、TG和BET等表征技术分析材料的结构特征。结果表明,当焙烧温度在500 ℃以下时,所制得的SO2-4/TiO2固体超强酸具有相近的优异酯化性能; 当焙烧温度提升至600 ℃以上时,SO2-4/TiO2的孔结构坍塌,SO2-4含量下降,酯化性能显著下降。经过水预处理后,所有固体超强酸酯化活性降低,主要与其SO2-4脱落和酸量明显减小有关。相比之下,400 ℃制备的SO2-4/TiO2固体超强酸催化剂具有较好的稳定性。
A water pretreatment method was used to evaluate the water-resistant stability of SO2-4/TiO2 solid superacid prepared by calcination under different temperatures. The structural properties of samples were characterized by the X-ray diffraction(XRD), NH3-TPD, fourier transform-infrared(FT-IR)spectroscopy, thermogravimetric(TG)analysis, and BET surface area analysis. The results showed that, when the calcination temperature did not exceed 500 ℃, the obtained SO2-4/TiO2 solid superacid had similar esterification performances. However, the pore structure of solid superacid collapsed and its SO2-4 content decreased when the calcination temperature exceeded 600 ℃. In this case, the esterification performance of the solid superacid was poor. After the water pretreatment, the esterification performances of all solid superacids descended, which was mainly attributed to the removal of SO2-4 and the decrease of acid amount. In a comparison, SO2-4/TiO2 solid superacid prepared at a calcination temperature of 400 ℃ had the optimum water-resistant stability