Granules on the basis of pyrogenic silica, process for their preparation and use thereof

摘要

Granulates (I) based on pyrogenic silica are claimed, with the following physical properties: - mean particle dia.: 10-120 microns - BET surface: 40-400 m<2>/g - pore vol.: 0.5-2.5 ml/g - pore size distribution: less than 5% of total pore vol. with a pore dia. less than 5 nm, the rest meso- and macro-pores -pH: 3.6-8.5 - tamped density: 220-700 g/l. Also claimed is the prodn. of (I) by dispersing pyrogenic silica in water and spray drying the dispersion. The granules obtd. are then (a) heated for 1-8 hrs. at 150-1100 deg.C; or (b) silanised; or (c) heat-treated as in (a) and then silanised.