Rare earth stabilized aluminum deficient zeolite

Claim 2

An aluminum deficient crystalline aluminosilicate zeolite having the crystal structure of a faujasite and having a composition, in its anhydrous state, in terms of mole ratio of oxides, as represented by the following formula: (1-Z) (aM.sub.2 O+bR.sub.2 O+3wRE.sub.2 O.sub.3) . (1-Z)Al.sub.2 O.sub.3.XSiO.sub.2 wherein RE represents a cation of a single rare earth metal or of a mixture of rare earth metals, wherein "w" ranges from a value of about 0.054 to about 0.217, said value w being the minimum amount of rare earth in said zeolite needed to stabilize said aluminum deficient zeolite; where R is an alkali metal cation; where M is selected from the group consisting of hydrogen ion, ammonium ion and mixtures thereof, wherein "a" ranges from zero to 1-3w; wherein "b" ranges from zero to 1-3w; wherein a+b+3w=1; wherein Z ranges from about 0.92 to 0.27, said value Z being the maximum fraction of alumina in the crystal structure that can be removed, and wherein X ranges from about 3.9 to about 54, said zeolite having a unit cell size ranging from about 24.25 to about 24.75 Angstroms, said zeolite having a unit cell size greater than the stoichiometric unit cell size when measured after heating for two hours at 1300° F., said zeolite falling within the area of FIG. 1 designated "stabilized zone".

Claim 3

The zeolite of claim 1 wherein said zeolite is composited with catalytic metals of Group IB, IIA, IIB, IIIB, IVA, IVB, VB, VIB, VIIB, VIII and mixtures thereof of the Periodic Table of Elements.

Claim 4

The zeolite of claim 1 wherein X equals 3.9 and said unit cell size is 24.75 Angstroms.

Claim 5

The zeolite of claim 1 wherein X equals 54 and said cell size is 24.25 Angstroms.

Claim 6

The zeolite of claim 1 wherein said zeolite is represented by the formula: 0.20(NH.sub.4).sub.2 O.0.05Na.sub.2 O.0.25RE.sub.2 O.sub.3.Al.sub.2 O.sub.3.9SiO.sub.2.

Claim 7

The zeolite of claim 1 having been prepared by the steps which comprise: (a) contacting a Y-type zeolite with a dealuminating agent for a time sufficient to remove at least about 5% of the aluminum atoms from said zeolite; (b) contacting the resulting dealuminized zeolite with a fluid medium comprising rare earth metal cations to produce a rare earth metal exchanged zeolite; and (c) calcining the rare earth exchanged zeolite to produce said aluminum deficient rare earth stabilized zeolite.

Claim 8

A method for the preparation of an aluminum deficient rare earth stabilized crystalline aluminosilicate zeolite, which comprises the steps of: (a) treating an initial Y-type crystalline aluminosilicate zeolite with a dealuminizing agent, said initial zeolite having the crystal structure of faujasite and having a composition, in its anhydrous state, in terms of mole ratios of oxides, represented by the formula: (aM.sub.2 O+bR.sub.2 O) . Al.sub.2 O.sub.3.XSiO.sub.2 wherein R represents an alkali metal cation; wherein M is a cation selected from the group consisting of hydrogen cation, ammonium cation, and mixtures thereof; wherein a+b =1; wherein "a" ranges from 0 to 1; wherein "b" ranges from 0 to 1; and wherein X ranges from 3.9 to 54; said zeolite having a unit cell size ranging from about 24.25 to about 24.75 Angstroms, said zeolite being treated at conditions and for a time sufficient to remove at least 5 percent of said aluminum from the structure of said zeolite; (b) contacting said zeolite during step (a) or after step (a) with an ion exchange medium comprising a rare earth metal cation to replace at least a portion of said M or R cation with a rare earth metal cation; and (c) recovering an aluminum deficient rare earth stabilized crystalline aluminosilicate represented by the formula of claim 1, and having a unit cell size greater than the stoichiometric unit cell size when measured after heating for two hours at 1300° F., and falling within the area of FIG. 1 designated "stabilized zone".

Claim 9

The method of claim 7 wherein said dealuminating agent is selected from the groups consisting of organic acids, inorganic acids, chelating agents and mixtures thereof.

Claim 10

The method of claim 7 wherein step (a) is conducted at a temperature ranging from 150 to 220° F. to remove at least about 5 percent of said aluminum from said crystal structure.

Claim 11

The method of claim 7 where said step (b) is conducted at a temperature ranging from about 60° F. to about 220° F.

Claim 12

The method of claim 7 wherein said initial zeolite has a silica to alumina mole ratio ranging from about 3.9 to about 54 and a unit cell size ranging from about 24.75 to about 24.25 Angstroms.