Study of sol–gel processing for fabrication of low density alumina microspheres

A sol–gel process for producing microspheres of low density alumina has been developed. A Dispal alumina sol and aluminum monohydrate were used as starting materials. Microspheres with spherical shape and controllable size have been produced by using a drop generation technique. The technique consists of producing a continuous stream of uniform droplets of alumina sol and then converting the drops into a rigid form by exposing them to an ammonium hydroxide gelation medium. By using this technique, alumina spheres with surface area 351 m 2 g −1 and pore size 10.7 A° have been prepared.