| Magnesium aluminate spinel (MgAl2O4) is one of the end-members of the spinel group minerals, which shows a unique combination of properties like high thermal stablity, high mechanical strength and hardness, high chemical inertness against both acidic and basic slag, abrasion resistance, low thermal expansion coefficient. Meanwhile, owing to its good catalytic activity and two active centers as acid and alkaline, MgAl2O4 spinel has been widely used as catalysts or catalyst support in chemical reactions. Nowadays MgAl2O4 spinel catalyst supports present the bad stability and easily lose its activity and so on in industrial application process. The main reason is that skeleton crystalline state of as-synthesized MgAl2O4 spinel is imperfect, particle size of supports is larger or imperfect calcination, which leads to diminishing specific surface area and pore volume of catalyst support. The paper's purpose is that hydration of alkoxide combines hydrothermal methed to prepare the MgAl2O4 catalyst support of perfect skeleton crystalline state, special surface topography and larger specific surface area, with a view to improve the performance of MgAl2O4 catalyst support and in favor of industrial application.The stoichiometric magnesium sheet and aluminum sheet were used as reagents to synthesize the Mgnesium-Aluminum double metal alkoxide. The synthesized alkoxide was hydrolyzed with deionized water under stirring, until generating the homogeneous sol. The hydrolyzate was added into high-pressure autoclave with magnetic stirrer for hydrothermal synthesis, dried and calcined. At last the products of special topography and pore structure were gained. The powders as-sythesized were characterized by TGA-DTA,SEM,TEM,XRD,and N2 adsorption-desorption isotherms to study the effect of different synthesis conditions on the properties of MgAl2O4 spinel or precursor, including hydrothermal temperature,hydrothermal duration,additive water content,surfactant CTAB and additive content,mineralizer and calination temperature, and so on.The results indicated that hydrolysate of Mgnesium-Aluminum double metal alkoxide was Mgnesium-Aluminum hydroxide compounds, mainly including MgAl2(OH)8, and the precursor was mainly composed of AlOOH and Mgnesium-Aluminum hydroxide compounds by hydrothermal reaction. With the increment of hydrothermal temperature and extension of hydrothermal duration, the phase composition of the precursor as-synthesized were not changed, just only intensity of diffraction peak had a little bit of increment, and relative content of both changed a little; the sheet of powder surface grew larger, and its specific surface area diminished gradually. MgAl2O4 spinel grew into blocky structure from sheet structure gradually and had lower specific surface area with the increment of adding water. The results indicated that MgAl2O4 spinel powders particle surface by hydrothermal method was made up of sheet structure. And it had wormlike pore structures and large specific surface area in a structure, which is a relic of the morphology even after calcination. By adding right amount of surfactant CTAB, the sheet structure of particle surface grew regularly, its pore structure was more regular and compacter, and had larger specific surface area, while the excess of surfactant CTAB had adverse effect.The effect of calcination temperature on MgAl2O4 spinel skeleton structure was the most significant. The spinel phase began to be formed at 450℃by hydrothermal reaction with alkoxide hydrolysate. And the perfect crystalline state skeleton structure was formed at 600℃. With the increment of calcination temperature, the diffraction peak intensity of samples increased gradually, the crystalline grain grew bigger and its specific surface area diminished gradually.
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