水热-溶胶-凝胶法制备高比表面积MgAl_2O_4尖晶石

Preparation of High Specific Surface Area MgAl_2O_4 Spinel by a Hydrothermal-Sol-Gel Method

以金属硝酸盐为原料,聚乙烯醇为稳定剂,在200℃水热反应温度下制备了氧化铝和氧化镁凝胶经700°C焙烧4h后获得高纯度、结晶完整的镁铝尖晶石(MgAl2O4)。用XRD、TG-DTA、SEM和BET等表征结果表明,加入PVA-124可以对胶体粒子起到保护作用,阻止胶粒因热运动碰撞而聚集,并使铝、镁氧化物胶粒均匀混合,在较低温度焙烧即可获得MgAl2O4尖晶石。当PVA-124加入量为20.8%,200℃水热温度制备的前驱体经700℃焙烧4h可获得表面积为153.3m2/g的镁铝尖晶石。

A hydrothermal-sol-gel route,using metal nitrates as precursors and PVA-124 as the stabilizer,was developed for the synthesis of high specific surface area MgAl2O4 spinel.The well crystallization and high-purity spinel can be obtained from the alumina and magnesium oxide gel prepared by hydrothermal reaction at 200℃ and then calcination at 700℃ in air for 4h.XRD,TG-DTA,SEM and BET results showed that the added PVA-124 could protect colloidal particles from aggregation caused by thermal motion of the collision,and enhance the mixing of alumina and magnesium oxide colloidal particles.The calcination temperature for MgAl2O4 spinel formation was lower than that reported by the conventional preparation methods.By adding 20.8% PVA-124,the specific surface area of MgAl2O4 spinel can reach 153.3m2/g.