SYNTHESIS OF COLLOIDAL SUSPENSIONS OF ZEOLITE ZSM-2

Discrete colloidal particles of zeolite ZSM-2 with crystal sizes less than 100 nm, in the form of aqueous suspensions, have been synthesized in tetramethylammonium (TMA)-aluminosilicate solutions in the presenc e of either lithium or a combination of lithium and sodium hydroxide. The well-crystallized ZSM-2 has a specific surface area of 781 m(2)/g after purification and removal of the organic base by calcination. Syn thesis times (t) are as short as 3 < t < 12 h and in certain cases, le ss than 3 h, less than those previously reported in the literature. Pr olonged hydrothermal treatment of sols in the presence of sodium catio ns (> 12 h) results in the phase transformation of ZSM-2 to the nitrog eneous edingtonite zeolite (Li,Na)-E. The synthesis of nitrogeneous (L i,Na)-E is also favored by a high TMA content in conjunction with sodi um, whereas synthesis of zeolite N-A is favored by a high sodium conte nt. Furthermore, it is shown that colloidal suspensions of TMA sodalit e with crystal sizes less than 40 nm are synthesized in the absence of alkali cations. (C) 1995 Academic Press, Inc.