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AssigneeSociete Nationale Elf Aquitaine
InventorsFrancois Delprato, Jean-Louis Guth, Didier Anglerot, Catherine Zivkov
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A process is provided for the preparation of zeolites belonging to the faujasite structural class and exhibiting a Si:Al ratio higher than 1 in which a reaction mixture is first produced which has a pH higher than 10 and contains water, a source of tetravalent silicon, a source of trivalent aluminum, a source of hydroxide ions in the form of a strong inorganic or orgnaic base and a structuring agent ST so as to produce an aluminosilicate gel having the desired composition to permit its crystallization into a compound of the faujasite structural class. The gel obtained is kept at a temperature, pressure and for a sufficient period to effect the crystallization of the gel into a precursor of the zeolite consisting of the zeolite trapping the structuring agent ST in its cavities and the precursor is then subjected to a calcination to destroy the structuring agent and to produce the zeolite. The structuring agent ST consists of at least one compound belonging to the group formed by the carbon-containing macrorings and macropolyrings which contain in the rings, heteroatoms chosen from oxygen, nitrogen, silicon and sulphur, and which contain 10 to 24 atoms per ring. Precursors of the zeolites are also provided.
A process for the preparation of zeolites belonging to the faujasite structural class and exhibiting a Si:Al ratio higher than 1, said process comprising first forming a reaction mixture which has a pH higher than 10 and contains water, a source of tetravalent silicon, a source of trivalent aluminum, a source of hydroxide ions in the form of a strong inorganic or organic base and a structural agent ST so as to produce an alumino silicate gel having the composition to permit its crystallization into a compound of the faujasite structural class, and the gel obtained is then kept at a temperature not exceeding 150.degree. C. and at a pressure of at least equal to the autogenous pressure of said gel for a sufficient period to effect the crystallization of said gel into a precursor of the zeolite consisting of the zeolite with the structural agent ST trapped in its cavities and said precursor is subjected to a calcination to destroy said structuring agent ST and to produce the zeolite, and wherein the structuring agent ST consists of at least one compound MC selected from the group consisting of carbon-containing macrorings and macropolyrings which contain in the rings heteroatoms selected from the group consisting of oxygen, nitrogen, silicon, and sulfur, and which contain 10 to 24 atoms per ring.
Precursors of zeolites of the faujasite structural class, consisting of aluminosilicates which have a Si:Al ratio higher than 1 and which, on the one hand, exhibit a structure of cubic symmetry comparable with that of faujasite or else a structure of hexagonal symmetry comparable with that of the hexagonal polytypes of faujasite or else comprise domains exhibiting a structure of cubic symmetry comparable to that of faujasite and domains exhibiting a structure of hexagonal symmetry comparable with that of the hexagonal polytypes of faujasite, and have cavities or channels trapping molecules of a structuring agent, ST, wherein the structuring agent ST consists of at least one compound MC, chosen from the group consisting of carbon-containing macrorings and macropolyrings which contain in the rings heteroatoms chosen from O, N, Si and S and which contain 10 to 24 atoms per ring, or results from the association of at least one compound MC with a costructurant CS consisting of at least one oxygen-containing acyclic compound chosen from the compounds of formula R.sub.1 --O--C.sub.m H.sub.2m-1 X--O].sub.8 R.sub.2, in which each of R.sub.1 and R.sub.2, which are identical or different, denotes a hydrogen atom or a C.sub.1 -C.sub.4 alkyl radical, X denotes a hydrogen atom or an OH radical, m is equal to 2 or 3 and may be different from one repeat unit to the other and g is a number ranging from 1 to 12.
A process for the preparation of zeolites which have the cubic symmetry structure of faujasite by calcination of the precursors of claim 38, the zeolites obtained having a cubic unit cell parameter value of between 2.4 and 2.5 nm, exhibiting an x-ray diffraction pattern comparable with that given in Table I below:
A process for the preparation of zeolites which have the hexagonal symmetry structure of the hexagonal polytypes of faujasite by calcination of the precursors of claim 29, the zeolites obtained having hexagonal unit cell parameters a,b,c, of the said structure such that 1.72 nm<a=b<1.77 nm and 2.80 nm<c<2.89 nm, exhibiting an x-ray diffraction pattern comparable with that given in Table II
A process for the preparation of precursors of zeolites belonging to the faujasite structural class and exhibiting a Si:Al ratio higher than 1, said process comprising first forming a reaction mixture which has a small pH higher than 10 and contains water, a source of tetravalent silicon, a source of trivalent aluminum, a source of hydroxide ions in the form of a strong inorganic or organic base and a structuring agent ST so as to produce an alumino silicate gel having the composition to permit its crystallization into a compound of the faujasite structural class, and the gel obtained is then kept at a temperature not exceeding 150.degree. C. and under a pressure at least equal to the autogenous pressure of said gel for a sufficient period to effect crystallization of the gel into a precursor of the zeolite consisting of the zeolite with the structuring agent ST trapped in its cavities and consisting of at least one compound MC selected from the group consisting of the carbon-containing macrorings and macropolyrings which contain in the rings heteroatoms selected from the group consisting of oxygen, nitrogen, silicon and sulfur, and which contain 10 to 24 atoms per ring.
Dependencies are inferred from the claim text.