Silica Coating on Carbonaceous Mesophase Spherules

Carbonaceous mesophase spherules (MS), prepared from coal-tar pitch, have a layer structure exposing the edgesof constituent aromatic molecules to the surface. Oxidation with nitric acid converted MS from hydrophobic to hydrophilicnature due to introduction of acidic functional groups to the surface. A water thin layer was formed on MS surface bysuspending oxidized MS in water followed by in benzene, i.e., W/O emulsion was formed. Na2O·nSiO2(n: 2.18-3.14) dissolved in the water layer was allowed to react with (NH4) 2SO4 to coat MS surface with silica. Detailed reaction conditions were clarified to successfully coat MS by silica. Silica-coated MS showed high BET surface area (as much as 200 times) compared with oxidized MS.