Abstract: A method is provided for zeolite synthesis from a synthesis medium containing in particular a trivalent aluminum source, a tetravalent silicon source, at least an alkaline or alkaline-earth cation in hydroxide form and water in a reactor containing a solid helical moving body in a guiding tube defining an internal space and a space external to the tube. The invention is characterized in that the synthesis medium is circulated in the reactor in a continuous flow passing through the internal space then the space external to the tube and returning to the internal space, only driven by the roation of the solid helical moving body, at a speed of less than 500 rpm, in the tube which is kept fixed, the synthesis medium being kept at a temperature suitable for at least one of the ripening operations or the crystal growth of the synthesized zeolite. The invention also is directed to a device for implementing the method.

Abstract: The invention provides an activated silica enriched mazzite having a chemical formula in the anhydrous state, expressed in molar ratios of:a M.sub.2/n O; Al.sub.2 O.sub.3 ; b SiO.sub.2 ;with a variation from 0 to 0.5, M being an alkaline cation of valency n and b being greater than 7, and which has an acid strength corresponding to an amount of heat measured by ammonia absorption microcalorimetry, greater than 190 KJ/mol, and a pore volume, measured by cyclohexane adsorption, greater than 0.09 ml/g. The activated mazzites are useful in the conversion of hydrocarbons, in particular, the isomerization of C.sub.4 to C.sub.8 paraffin, and as molecular sieves in processes for the separation of hydrocarbons.

Abstract: Silica-bound extruded zeolites may be converted into binder-free zeolite aggregates by aging the zeolite in an aqueous ionic solution which contains hydroxy ions such that the initial molar ratio of OH.sup.- :SiO.sub.2 is up to 1.2 and which causes the silica binder to be converted substantially to zeolite of the type initially bound. Such extrudates have excellent mechanical strength and show advantageous properties such as adsorption comparable with non-extruded zeolite powder.

Abstract: Molecular sieve compositions are prepared by extracting aluminum and substituting chromium and/or tin for extracted aluminum to give molecular sieve products containing framework chromium and/or tin atoms. The process of preparing the chromium and/or tin-containing molecular sieves involves contacting a starting molecular sieve with a solution or slurry of at least one of a fluoro salt of chromium or a fluoro salt of tin under effective process conditions to provide for aluminum extraction and substitution of chromium and/or tin.

Abstract: Silica-bound extruded zeolites may be converted into binder-free zeolite aggregates by aging the zeolite in an aqueous ionic solution which contains hydroxy ions such that the initial molar ratio of OH-:SiO.sub.2 is up to 1.2 and which causes the silica binder to be converted substantially to zeolite of the type initially bound. Such extrudates have excellent mechanical strength and show advantageous properties such as adsorption comparable with non-extruded zeolite powder.

Abstract: Process for the preparation of a crystalline aluminosilicate enriched in silica, having the structure of mazzite, by hydrothermal crystallization of a gel containing sources of silicon, aluminum and alkali metal ions, in the presence of an organic structuring agent, characterized in that the source of aluminum is a zeolite Y in the form of spheres. The mazzite obtained does not contain any silicoalumina debris out of the lattice. It is employed as catalyst for the conversion of hydrocarbons or as molecular sieve.

Abstract: This invention relates to a new zeolite from the class of mazzite, containing a fraction of non-exchangeable potassium cations, and also to a process for its synthesis. The crystallinity and the adsorption capacity of the protonated form of this zeolite are maintained after a prolonged hydrothermal treatment.