Silicon substituted zeolite compositions and process for preparing same

Claim 2

Method for inserting silicon atoms as SiO 4 tetrahedra into the crystal lattice of an aluminosilicate zeolite which comprises contacting a crystalline zeolitic aluminosilicate having a SiO 2 /Al 2 O 3 molar ratio of at least 3 and pore diameters of at least 3 Angstroms with a fluorosilicate salt in an amount of at least 0.0075 moles per 100 grams of the zeolitic aluminosilicate on an anhydrous basis, said fluorosilicate salt being in the form of an aqueous solution having a pH value within the range of 3 to about 7 and brought into contact with the zeolitic aluminosilicate at a rate sufficiently slow to preserve at least 60 percent of the crystallinity of the starting zeolitic aluminosilicate.

Claim 3

Method according to claim 1 wherein the starting crystalline zeolitic aluminosilicate is at least partially in the ammonium cationic form.

Claim 4

Method according to claim 2 wherein the fluorosilicate salt is ammonium fluorosilicate.

Claim 5

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite Y.

Claim 6

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of mordenite.

Claim 7

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite omega.

Claim 8

Method according to claim 2 wherein the starting zeolite aluminosilicate has the essential crystal structure of zeolite Rho.

Claim 9

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite L.

Claim 10

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite W.

Claim 11

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite N-A.

Claim 12

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of offretite.

Claim 13

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of clinoptilolite.

Claim 14

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of chabazite.

Claim 15

Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of erionite.

Claim 16

Method according to claim 1 wherein the starting zeolitic aluminosilicate is zeolite Y having a SiO 2 /Al 2 O 3 molar ratio of from 3 to 7, the reaction is carried out at a temperature of from 20° to 95° C. and the fluorosilicate salt is employed in an amount at least as great as determined from the equation AFS=1.395a-0.275 wherein AFS is the minimum number of moles of fluorosilicate salt per 100 grams of zeolite starting material on an anhydrous basis and "a" is the mole fraction of framework aluminum tetrahedra of the starting zeolite Y as represented by the expression (Al a Si b □ z )O 2 wherein Al represents framework aluminum tetrahedra, Si represents framework silicon tetrahedra and □ represents defect sites, "b" is-the mole fraction of silicon tetrahedra and "z" is the mole fraction of framework defect sites.

Claim 17

Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expessed in terms of mole ratios of oxides 0.9±0.1M.sub.2/n O:Al.sub.2 O.sub.3 :XSiO.sub.2 wherein "M" is a cation having the valence "n" and "x" is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO 4 tetrahedra.

Claim 18

Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expessed in terms of mole ratios of oxides 0.9±0.1M.sub.2/n O:Al.sub.2 O.sub.3 :XSiO.sub.2 wherein "M" is a cation having the valence "n" and "x" is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO 4 tetrahedra.

Claim 19

Composition according to claim 16 wherein the value of "x" is from 8 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A 3 .

Claim 20

A crystalline aluminosilicate having an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and having at least some of its original framework aluminum atoms replaced by extraneous silicon atoms and having the chemical composition [Al.sub.(a-N) Si.sub.b+(N-Δz) □.sub.z ]O.sub.2 wherein Al.sub.(a-N) represents the mole fraction of aluminum tetrahedra in the product zeolite; "a" represents the mole fraction of aluminum tetrahedra in the original zeolite; "N" represents the mole fraction of aluminum tetrahedra removed from the original zeolite, and has a value of at least 0.3a; Si b+ (NΔz) represents the mole fraction of silicon tetrahedra in the product zeolite; "b" represents the mole fraction of silicon tetrahedra in the original zeolite; (N-Δz) represents the mole fraction of silicon tetrahedra resulting from the substitution of extraneous silicon into the crystal lattice; "□" represents framework defect sites; "z" represents the mole fraction of framework defect sites; "Δz" represents the difference between the mole fraction of framework defect sites of the original zeolite and the zeolite containing the extraneous silicon atoms and has a value of less than 0.08; (N-Δz)/N has a value at least as great as 0.5; and [b+(N-Δz)]/(a-N) has a value of at least 4.0.

Claim 21

A crystalline aluminosilicate having an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and having at least some of its original framework aluminum atoms replaced by extraneous silicon atoms and having the chemical composition [Al.sub.(a-N) Si.sub.b+(N-Δz) □.sub.z ]O.sub.2 wherein Al.sub.(a-N) represents the mole fraction of aluminum tetrahedra in the product zeolite; "a" represents the mole fraction of aluminum tetrahedra in the original zeolite; "N" represents the mole fraction of aluminum tetrahedra removed from the original zeolite, and has a value of at least 0.3a; Si b+ (NΔz) represents the mole fraction of silicon tetrahedra in the product zeolite; "b" represents the mole fraction of silicon tetrahedra in the original zeolite; (N-Δz) represents the mole fraction of silicon tetrahedra resulting from the substitution of extraneous silicon into the crystal lattice; "□" represents framework defect sites; "z" represents the mole fraction of framework defect sites; "Δz" represents the difference between the mole fraction of framework defect sites of the original zeolite and the zeolite containing the extraneous silicon atoms and has a value of less than 0.08; (N-Δz)/N has a value at least as great as 0.5; and [b+(N-Δz)]/(a-N) has a value of at least 4.0.

Claim 22

Composition according to claim 18 wherein the value of Δz is less than 0.05.

Claim 23

Composition according to claim 18 wherein the zeolite aluminosilicate has a cation equivalent expressed as a monovalent cation species, M + /Al, of 0.9±0.1.