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