物理化学学报 >> 2000, Vol. 16 >> Issue (02): 105-110.doi: 10.3866/PKU.WHXB20000203

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硝酸镁在γ-Al2O3上的热分解及MgO/γ-Al2O3

江德恩, 赵璧英, 谢有畅   

  1. 北京大学物理化学研究所，北京 100871
  • 收稿日期:1999-05-12 修回日期:1999-06-21 发布日期:2000-02-15
  • 通讯作者: 赵璧英

Thermal Decomposition Behavior of Mg(NO3)2 on γ-Al2O3 and Basicity of MgO/γ-Al2O3

Jiang De-En, Zhao Bi-Ying, Xie You-Chang   

  1. Institute of Physical Chemistry,Peking University,Beijing 100871
  • Received:1999-05-12 Revised:1999-06-21 Published:2000-02-15
  • Contact: Zhao Bi-Ying

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摘要：

研究了不同载量时Mg(NO3)2 在γ-Al2O3 上存在状态和热分解行为差异. 考察了Mg含量不同时MgO/γ-Al2O3 的碱性变化情况 ,并与水滑石焙烧产物Mg(Al)O的碱性进行了对比.结果表明, Mg(NO3)2 可单层分散于γ-Al2O3 表面 ,Mg(NO3)2 的分散决定了MgO的分散阈值 ;单层态的Mg(NO3)2 比晶态的分解温度低 ;MgO/γ-Al2O3 在阈值附近具有单位表面最高碱量 ,碱位分布与Mg(Al)O相似 ,单位表面碱量高于Mg(Al)O. 由于γ-Al2O3 的织构可以方便地调节 ,且MgO/γ-Al2O3很容易制备, MgO/γ-Al2O3 是一个很有应用前景的固体碱.

关键词: Mg(NO3)2/γ-Al2 O3, MgO/γ-Al2O3, 负载型固体碱, 热分解, CO2-TPD

Abstract:

The state and thermal decomposition behavior of Mg(NO3)2 on γ-Al2O3 at different Mg loading were studied by XRD and TG DTA. The basicity of MgO/γ-Al2O3 with different Mg loading was investigated by CO2 TPD and compared with t hat of Mg Al mixed oxides derived from hydrotalcite. Results show that Mg(NO3)2 can disperse on γ Al2O3 as a monolayer and its dispersion determines the dispersion threshold of MgO on γ-Al2O3. Mg(NO3)2 in dispersion state has lower decomposition temperature than that in crystal state. The amount of basic sites per square meter on the surface of MgO/γ-Al2O3 shows a highest value around the loading of threshold, which indicates that the basicity of MgO/γ-Al2O3 originates from MgO in dispersion state. The basicity of MgO/γ-Al2O3 around the thresh old loading is comparable and even superior to that of Mg(Al)O derived from hydrotalcite. Since the texture and specific area of γ-Al2O3 can be easily adapted and there are various kinds of commercial γ-Al2O3 available, MgO/γ-Al2O3 is a promising solid base that may be found in use.

Key words: Mg(NO3)2/γ-Al2 O3, MgO/γ-Al2O3, Supported solid base, Thermal decomposition, CO2-TPD