海藻酸辅助溶胶-凝胶法制备球形氧化铝颗粒

以2种不同的拟薄水铝石(PB)和海藻酸钠(ALG)为原料,采用海藻酸辅助溶胶-凝胶法制备γ-Al2O3颗粒.用氮气吸附-脱附、强度测定仪、XRD、SEM、XRF对样品进行表征;考察了2种拟薄水铝石的胶溶指数;研究了不同拟薄水铝石配比及胶溶剂硝酸处理时间对氧化铝颗粒物化性质的影响.结果表明:拟薄水铝石的胶溶指数是影响颗粒强度的重要因素;采用不同的拟薄水铝石进行配比,可调控氧化铝颗粒的孔结构及强度;随着硝酸处理时间的延长,氧化铝颗粒的比表面积、孔容和孔径逐渐降低,钙含量也随之降低,但颗粒的强度随着处理时间的延长而增大,并在15,min时达到最大值104,N,继续延长处理时间强度出现一定程度的降低;硝酸处理过程改变了拟薄水铝石粒子的大小和堆积方式,并没有改变γ-Al2O3的物相结构.

Preparation of Spherical Alumina by Alginate Assisted Sol-Gel Method

Spherical γ-alumina granules were prepared by alginate assisted sol-gel method using two different types of pseudoboehmite （PB） and sodium alginate （ALG） as raw materials. The samples were characterized by N2 adsorptiondesorption, tensile tester, XRD, SEM and XRF. Dispersion indexs of two PB samples were investigated; the influence of the ratio of two different PBs and the treating time of nitric acid on the properties of spherical y-alumina was studied. Results indicate that the crushing strength of y-alumina is influenced by dispersion index of PB; regulable pore structure and crushing strength of alumina granules can be obtained by changing the mass ratio of two different PBs. The surface area, pore volume, pore size and calcium contents decrease with the increase of treating time of nitric acid while crushing strength of the sample is increased to about 104 N after 15 min and is decreased by continuing to prolong the treating time; pore size and packing mode of PB is changed by the nitric acid treating process, but the phase structure ofy-Al2O3 is not changed.