Synthesis of Hydrophobic Silicalite Adsorbent from Domestic Resources: The Effect of Alkalinity on the Crystal Size and Morphology

Document Type : Research Article


Research Institute of Petroleum Industry (N.I.O.C.), Catalysis Research Center, P.O. Box 18745-4163, Tehran, I.R. IRAN



A new polymorph crystalline silica composition having uniform pore dimensions were synthesized by calcining a crystalline hydrated alkyl-ammonium silicate. The pore dimensions approximately were 6 angstrom for silicalite-1 and 11 angstrom for silicalite-2 units. The silicalite-1 was prepared hydrothermally at a pH of about 10 from a reaction mixture consist of water, amorphous silica and a quaternary ammonium compound. Domestic water glass was ion-exchanged to produce silicasol. In this work we also investigated the influence of alkalinity percent in the starting gel mixture on the crystal shape and size.


Main Subjects

[1] Grose, W. R. and Flanigen, E. M., Crystalline silica, US-Patent, 4,061,724 (1977).
[2] Flanigen, E. M. and Patton, R. L., Silica polymorph and process for preparing same, US-Patent, 4,073,865 (1976).
[3] Bibby, D.M., Milestone, N.B. and Aldridge, L.P., Nature, 280, pp. 644-665 (1979).
[4] KunGang, T. and Ruren, X., “The influence of alkali metal cations on the formation of silicalite in NH4OH-TPABr system”, Zeolites, Drzaj, B., Hocevar, S. and Pejonvik, S. (Editors), Elsevier Science Public-ation, pp. 73-80 (1985).
[5] Barrer, R.M., Zeolites, 1, 130 (1980).
[6] Mostowies, R. and Sand, L., Zeolites, 2, 143 (1982).
[7] Haegh, G.S., “ Zeolites as adsorbents for alcohols from aqueous solutions”, Zeolites, Drzaj, B., Hocevar, S. and Pejonvik, S. (Editors), Elsevier Science Publication, pp. 609-615 (1985).
[8] Vakili, D. and Irankhah, A., “ Study of  selective adsorption properties of more applicable industrial hydrocarbons via silicalite-1”, 8th Iranian Chemical Engineering Congress, Ferdowsi University, Mashhad, Iran, Oct. (2003).
[9] Hou, L.Y. and Sand, L.B., “ Determination of boundary conditions of crystalization of ZSM5-ZSM11 in one ‘Al-Free’ system: ZSM5-ZSM11 boundary condit-ions”, 6th International Zeolite