Effect of Lanthanum and Cerium Modifiers on Properties of Alumina
Effect of Lanthanum and Cerium Modifiers on Properties of Alumina
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发表时间：
2003
影响因子：
16.5
通讯作者：
Lu Weiguang
中科院分区：
文献类型：
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作者：
Lu Weiguang
研究了稀土氧化物（La和Ce）对溶胶法制备高比表面积氧化铝性能的影响。采用红外光谱、x射线衍射、BET表面积测定等方法研究了氧化铝的水热稳定性。在标准固定床反应器系统中进行了氧化铝对正十六烷裂解和环己烷脱氢的反应性实验。结果表明，添加剂对氧化铝的比表面积、孔体积、孔径、羟基含量、裂化和脱氢活性等性能均有影响。La和Ce减少了氧化铝表面羟基的数量，明显阻止了1*!处的烧结和α-相的形成。000℃。在高温下，ce3 +被氧化为ce4 +并分离为ce2。烧结动力学研究表明，γ -氧化铝是通过体扩散烧结的。ce改性氧化铝比la改性氧化铝具有更高的裂化活性和脱氢活性。
The effect of rare earth oxides (La and Ce) on the properties of high surface area alumina prepared from pseudo-boehmite by the sol method was studied. The hydrothermal stability of alumina was investigated by IR spectroscopy, X-ray diffraction, and BET surface area measurement. The reactivity experiments of alumina for the cracking of n-cetane and dehydrogenation of cyclohexane were conducted in a standard fixed-bed reactor system. The results show that the additives influence the properties of alumina, such as surface area, pore volume, pore diameter, amount of hydroxyl group, and cracking and dehydrogenation activity. The La and Ce species decrease the amount of surface hydroxyl group of alumina and obviously prevent the sintering and α-phase formation at 1*!000 ℃. At high temperature Ce 3+ is oxidized to Ce 4+ and segregates as CeO 2. The sintering kinetic studies show that gamma alumina sinters via bulk diffusion. Ce-modified alumina shows higher cracking activity and dehydrogenation activity than La-modified alumina.