制备条件及添加稀土对SO42- /ZrO2 -Al2O3固体超强酸酸性影响的研究

用共沉淀法制备了SO42-/ZrO2-Al2O3固体超强酸,并采用低温陈化和添加稀土La对其制备方法进行改进.通过样品催化正丁烷异构化反应考察了该固体超强酸中nZr和nAl的最佳配比为1∶ 2.该法制备的样品的IR显示,在1393 cm-1处的吸收峰强度较常温陈化样品大大增加.XRD分析表明,低温陈化和加入稀土添加剂的样品在650℃焙烧温度下,出现了亚稳态的ZrO2 四方晶相的晶体是表面酸性和催化活性增加的微观原因.样品催化合成八乙酸蔗糖酯反应结果同样证明,在相同的时间内,低温陈化和添加稀土添加剂的样品具有较好的催化活性.

Study on Preparation of SO42-/ZrO2-Al2O3 Solid Superacid by Improving Preparation Condition and Adding Lanthanum

Various superacid SO42-/ZrO2-Al2O3catalysts were prepared by a coprecipitation, and modified by aging at low temperature and addition of the rare earth oxide, such as La2O3. A optimum atomic ratio of Zr/Al was found to be 0.5, which was confirmed by the catalytic activity of samples forn-butane isomerization . IR measurements demonstrated that the intensity of the peak at 1393cm-1for the samples aged at low temperature and containing the rare earth oxide was more higher than that for the samples at room temperature. For the sample containing the RE oxide and aged at low temperature, XRD observed a metastable tetragonal phase of ZrO2crystal which is responsible for the higher catalysis activity as we believe. The observation of catalytic activity for esterification of sucrose further evidenced the conclusion mentioned above.