Preparation of Sol-Gel Spheres Smaller than 200 Microns without Fluidization

The preparation of sol-gel spheres by extraction of water into organic alcohols is simpler for nonfluidizing conditions as compared to fluidized-bed operation. However, the maximum sphere diameter that can be produced is typically 200 microns (μ) or less. The column heights required were calculated from mass transfer and settling correlations. Sol drops with mean diameters of 20 to 300 μ were formed by using two-fluid nozzles with turbulent flow of alcohol drive fluid in the nozzle. Water is removed from the alcohols by distillation, and surfactants may be added to control operating problems.