Structural evolution of calcium-exchanged (NH4)2SiF6-dealuminated Y zeolite after various chemical treatments

L. Cherif (1) , F.-Z. El-Berrichi (1) , A. Bengueddach (2) , P. Tougne (3) , J. Fraissard (3)

1 Laboratoire de Catalyse et Synthèse Organique,
2 Laboratoire de Chimie des Matériaux
3 SIEN - Systèmes interfaciaux à l'echelle nanometrique

The structural evolution of Y zeolite (Si/Al 2.17) weakly dealuminated by hexafluorosilicate (Si/Al 3.13), denoted YD, and exchanged with calcium (CaYD), has been studied after acid/base treatments at 80 8C close to the cation exchange conditions. The stability of the samples was followed by X-ray diffraction and solid-state NMR of 29Si and 27Al; YD zeolite was completely destroyed by treatment with acid pH 2.5 and suffered serious degradation on treatment with alkali at pH 11.8. The introduction of calcium improved the stability of the zeolite in acid and base. In acid CaYD was not destroyed until pH 1. At pH 2, silicon and aluminium were extracted and an amorphous phase was formed. Base treatment at pH 13 did not affect the calcium-exchanged zeolite.

Mots clés: Zeolite; Extra-framework silicon and aluminium; Dealumination

Domaines: Autre

L. Cherif, F.-Z. El-Berrichi, A. Bengueddach, P. Tougne, J. Fraissard. Structural evolution of calcium-exchanged (NH4)2SiF6-dealuminated Y zeolite after various chemical treatments. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003, 220, pp.83-89. ⟨hal-00162317⟩