SNTHESIS OF GALLO- AND GALLO-ALUMINO ZSM-5 ZEOLITES WITH VARIABLE AND QUASI-HOMOGENEOUS AL-GA DISTRIBUTION, FROM ALKALI-FREE MEDIA

ABSTRACT A new synthesis route leading to a rapid crystallization of alkali-free gallo-, alumino-, or gallo-alumino MFI-type zeolites from methylamine-Pr 4 N + media, was proposed. Methylamine plays a similar mobilizing-complexing role towards both Al 3+ and Ga 3+ ions so that they are quasi-homogeneously distributed in the final zeolite lattice. Mild (hydro)thermal treatments of the as-synthesized materials directly yield the protonated forms involving quite strong Bronsted acid sites. While the Al species remain stable in the framework, gallium is partly extracted from the lattice upon these treatments. The framework Ga stability appears to be markedly dependant on the actual lattice Al concentrations