Dealumination of aluminosilicate zeolites

• US 4,753,910 A
• Filed: 02/17/1987
• Issued: 06/28/1988
• Est. Priority Date: 02/17/1987
• Status: Expired due to Fees

• Current Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Han, Scott, Shihabi, David S.
• Primary Examiner(s): DEES, CARL
• Application Number:
  US07/015,651
• Time in Patent Office: 497 Days
• Field of Search: 502/85, 423/328
• US Class Current: 502/85
• CPC Class Codes: B01J 2229/16 to increase the Si/Al ratio; Dealumination
• CPC Class Codes: B01J 29/06 Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
• CPC Class Codes: Y10S 423/21 Faujasite, e.g. X, Y, CZS-3, ECR-4, Z-14HS, VHP-R
• CPC Class Codes: Y10S 423/22 MFI, e.g. ZSM-5. silicalite, LZ-241

Abstract

In a method of removing tetrahedral aluminum from a aluminosilicate zeolite, the zeolite is treated with an aqueous fluorosilicate solution which reacts with tetrahedral aluminum in said zeolite to produce water-insoluble aluminum fluoride. In addition, during or after the aluminum removal, the zeolite is contacted with an aqueous solution containing a water-soluble fluoride of reacting with the insoluble aluminum fluoride to produce a water-soluble species.

Claims

1. A method of removing tetrahedral aluminum from an aluminosilicate zeolite containing at least 50 ppm of tetrahedral aluminum, comprising the steps of:

(a) contacting the zeolite with an aqueous solution containing a fluorocompound of an element different from aluminum capable of reacting with tetrahedral aluminum in said zeolite to remove said tetrahedral aluminum from the zeolite lattice and produce a water-insoluble aluminum fluoride; and

(b) contacting the zeolite with an aqueous solution containing a water-soluble fluoride MF_n where M has a valence of n and is selected from the group consisting of hydrogen, ammonium and a metal of Group I or Group II of the Periodic Table capable of reacting with insoluble aluminum fluoride to produce a water-soluble species.

2. The method of claim 1 wherein the zeolite is zeolite Y.

3. The method of claim 1 wherein the zeolite is zeolite beta.

4. The method of claim 1 wherein the zeolite is ZSM-5.

5. The method of claim 1 wherein said fluorocompound is selected from the group consisting of a fluorosilicate and a fluorotitanate.

6. The method of claim 5 wherein the fluorocompound is ammonium fluorosilicate.

7. The method of claim 1 wherein said aqueous solution contains at least 0.0075 moles of the fluorocompound per 100 g of the anhydrous zeolite.

8. The method of claim 1 wherein said fluoride MF_n is ammonium fluoride.

9. The method of claim 1 wherein steps (a) and (b) are conducted substantially simultaneously using an aqueous solution containing said fluorocompound as said fluoride MF_n.

10. The method of claim 9 wherein steps (a) and (b) are conducted at 20°

-125°

C. for 0.2-300 hours.

11. The method of claim 9 wherein said aqueous solution is 0.001-3N in said fluoride MF_n.

12. The method of claim 1 wherein step (a) is conducted prior to step (b).

13. The method of claim 12 wherein said aqueous solution is 0.001N to 5N in said fluoride MF_n.

14. The method of claim 12 wherein step (b) is conducted at 20°

to 100°

C. for 0.005 to 20 hours.