高比表面积Ce-Zr-O复合氧化物的制备与表征

以 Ce(NO3 ) 3 · 6 H2 O和 Zr(NO3 ) 4· 5 H2 O为原料 ,采用共沉淀法 ,合成了高比表面积的 Ce- Zr- O复合氧化物 .实验结果表明表面活性剂的添加量 ,溶液的 p H值及陈化时间等对比表面积的增加影响较大 .当表面活性剂的添加量为 70 % ,p H值为 9.5 ,陈化时间为 12 0 h,92 3K焙烧 2 h后 ,样品的比表面积达到 2 79.6 9m2 / g.FT- IR分析显示 ,样品经 92 3K焙烧后 ,Ce- Zr- O上残留的活性剂已基本除去 .TG- DTA分析表明 35 3K干燥后的样品在 TG曲线上有两个明显的失重过程 ,与 DTA曲线相对应有两个吸热峰 ,第一个表示吸附水和丙酮的脱去过程 ,温度在 393K,失重率为 7.4 3% ;第二个吸热峰在787K,可能是表面活性剂的分解峰 .氮气的吸 -脱附实验揭示 ,该吸 -脱附等温线属于 型等温线 ,是中孔多孔物质的吸附类型 .另外 ,样品经 973K焙烧 ,比表面为 2 30 .6 9m2 / g;10 73K焙烧后 ,比表面为12 0 .5 5 m2 / g;经 1173K焙烧 ,仍有 5 3.5 3m2 / g.

Preparation and characterization of Ce-Zr mixed oxide with high surface area

The Ce-Zr mixed oxides with high surface area were synthesized from Ce(NO 3) 3 and ZrO(NO 3) 2 by co-precipitation method. Experimental results showed that the amount of surfactant added, pH value, and the gel aging time contribute largely to the increment of specific surface area of the samples. The specific surface area of the sample reaches to 279.69m 2/g when 70% of surfactant was added and at pH 9.5, aging time 120h, and calcining temperature 923K. The FT-IR spectra show that the surfactants remaining on the mixed oxides are almost removed after the samples were calcined at 923K. There are two weight-loss processes revealed in TG curve after the samples were dried at 353K. This is in assistant with two heat absorption peaks at 393K and 787K in DTA curve. The peak at 393K is related to desorption of acetone and water. Its weight loss is 7.43%. The peak at 878K may be related to the decomposition of surfactant. Nitrogen adsorption-desorption experiments proved all materials to be porous. The N 2-adsorption isotherms of all powders are of type IV, a typical pattern for a mesoporous sample.