MoO3改性SO42-/Al2O3-ZrO2固体酸的制备和表征

以硝酸锆为锆源、硝酸铝为铝源，采用共沉淀法制备了Al₂O₃-ZrO₂复合载体，通过MoO₃改性和H₂SO₄浸渍法制备了MoO₃改性的SO₄^2-/Al₂O₃-ZrO₂催化剂。用XRD和FT-IR对催化剂进行表征，用元素分析仪测定硫含量，用乙酸和正丁醇的酯化反应对其催化活性进行考察。结果发现，当MoO₃添加质量分数达12.0%时，出现MoO₃衍射峰，表明适当的MoO₃可以单层分布在催化剂表面，从而稳定SO₄^2-的存在。FT-IR分析结果表明，催化剂具有固体酸的特征峰。在MoO₃添加质量分数为8.0%和焙烧温度650 ℃时，催化剂的催化活性达最大值，催化活性与硫含量的增加不一致。

Preparation and characterization of molybdate-promoted SO4^2-/Al2O3-ZrO2 solid acid catalysts

MoO₃-modified SO₄^2-/Al₂O₃-ZrO₂ were prepared by co-precipitation and impregnation method, using zirconium nitrate and aluminum nitride as the zirconium and aluminum source. The catalysts were characterized by element analysis, FT-IR and XRD. The activity of SO₄^2-/Al₂O₃-ZrO₂ was investigated for esterification of acetic acid and n-butanol. XRD results indicated that there were MoO₃ diffraction peaks when content of MoO₃ exceeded 12.0%(mass fraction), which meant that appropriate amount of MoO₃ results in single layer dispersion on the surface and hence stabilized sulfate. FT-IRresulted showed that there were typical characteristic adsorption peaks for solid superacid in the catalysts. Appropriate amount of sulfur were enhanced the catalytic activity. Optimum catalytic activity was attained when adding 8.0%(mass fraction) MoO₃ and calcined at 650 ℃.