Synthèse des zéolites. Perspectives d'avenir

¹ Laboratoire de Matériaux Minéraux, E.N.S.C. Mu, 3 rue Alfred Werner 68093 Mulhouse Cedex, France.
² Laboratoire de Matériaux Minéraux, E.N.S.C. Mu, 3 rue Alfred Werner 68093 Mulhouse Cedex, France.

Résumé

Après un historique de la synthèse, le problème du mécanisme de formation est abordé. Si la nucléation et la croissance ont probablement lieu en solution, la question de la nature des espèces solubles présentes reste posée. Les analogies de structure entre glaces et clathrates d'eau et silices et silicates, les corrélations entre compositions et structures des zéolites, sont quelques-uns des éléments permettant d'apporter des réponses partielles à ce problème. En dernier lieu les perspectives futures de recherche sont presentées.

Abstract

After a historical survey of zeolite synthesis, the problem of their formation mechanism is considered. Many experimental facts, particularly the existence of a real solubilization equilibrium, point out that crystallization occurs probably from dissolved species. The nature and the part taken by such species responsible for nucleation and growth is not completely known. The results of studies on aqueous silicate and aluminosilicate solutions, the analogies observed between the structure of ice and water clathrates on one hand, and the structures of silica and silicates on the other hand and the correlations between composition and structure of zeolites are some of the answer elements to this question. In the case of zeolites of low silica content, the complex I aluminosilicate anion + charge compensating cations + hydration molecules I has a structure-directing effect on the framework building; in the case of silica-rich zeolites it is the structuring of water due to the organic species which plays such a role. A genetic classifying of zeolites in five groups is proposed. Finally the future research prospects on zeolite synthesis are examined.