KINETIC INVESTIGATION OF THE EFFECT OF NA, K, LI AND CA ON THE CRYSTALLIZATION OF TITANIUM-SILICATE-ETS-4

Titanium silicate ETS-4 was synthesized in Na, Na-K, Na-Li, and Na-Ca containing gels. The partial replacement of sodium with potassium lead s to a change in the kinetics behavior of the crystallization curves, which becomes a function of the content of potassium in the gel. The p resence of calcium or lithium in the initial gel increases substantial ly the nucleation time and the time to attain a maximum degree of crys tallinity (Na/Ca = 3.5 and Na/Li = 3.5). The higher concentration of c alcium and lithium (Na/Ca = 2.6 and Na/Li = 2.6) leads to the formatio n of dense calcium- and lithium-containing phases. AII the cations use d change strongly the morphology of the grown ETS-4 crystals. (C) Else vier Science Inc. 1997.