New method for the preparation of nonuniform distributed Co/SiO2 catalysts

Egg-shell, egg-yolk and egg-white types of Co/SiO2 catalysts were prepared by utilizing entrapped air to inhibit the entrance of impregnation or leaching solution into the cores of catalyst pellets during the preparation procedure; the entrapped air played the important role because the capillary pressure was reduced to a suitable range by adjusting the concentration of ethanol in the impregnation or leaching solution for a hydrophobized silica surface.