Non-hydrothermal method of making a titanium-containing zeolite

• US 5,688,484 A
• Filed: 07/29/1996
• Issued: 11/18/1997
• Est. Priority Date: 07/29/1996
• Status: Expired due to Term

• Current Assignee: Lyondell Chemical Technology LP (Lyondellbasell Industries NV)
• Original Assignee: ARCO Chemical Technology, L.P. (Lyondellbasell Industries NV)
• Inventors: Saxton, Robert J., Zajacek, John G.
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): TROILO, LOUIS
• Application Number:
  US08/681,585
• Time in Patent Office: 477 Days
• Field of Search: 423/700, 423/701, 423/702, 423/704, 423/705, 423/709, 423/714, 423/DIG. 22, 423/328.2
• US Class Current: 423/700
• CPC Class Codes: C01B 37/005 Silicates, i.e. so-called metallosilicalites or metallozeosilites
• CPC Class Codes: Y10S 423/22 MFI, e.g. ZSM-5. silicalite, LZ-241

Abstract

A process for producing a titanium-containing zeolite such as TS-1 titanium silicalite is disclosed. A precursor mixture comprising a silica source such as tetraalkylorthosilicate, a titanium source such as titanium alkoxide, a growth medium comprising a nitrogen-containing organic base such as an amine, a fluoride-containing mineralizing agent such as hydrogen fluoride, and an optional organic solvent, is formed then heated to yield the titanium-containing zeolite as solid crystals. A controlled amount of water may be present in the growth medium. The process is capable of providing good yields of high purity zeolites containing framework titanium atoms even in the absence of a quaternary ammonium salt.

Claims

1. A non-hydrothermal method of making a titanium-containing zeolite comprising:

(i) preparing a precursor mixture comprised of

(a) a silica source;

(b) a titania source; and

(c) a growth medium comprising a nitrogen-containing organic base, a fluoride-containing mineralizing agent, and, optionally, an organic solvent which does not prevent mineralization of the silica source and the titania source; and

(ii) heating said precursor mixture for a time and at a temperature sufficient to form as-synthesized titanium-containing zeolite.

2. The method of claim 1 wherein the nitrogen-containing organic base is selected from the group consisting of primary alkylamines, secondary alkylamines, tertiary alkylamines, N-heterocycles, and mixtures thereof.

3. The method of claim 1 wherein the temperature is from 100°

C. to 200°

C.

4. The method of claim 1 wherein the molar ratio of fluoride to (Ti+Si) is from 0.5 to 5.

5. The method of claim 1 wherein the silica source is a tetraalkylorthosilicate.

6. The method of claim 1 wherein the titania source is a titanium alkoxide.

7. The method of claim 1 wherein the fluoride-containing mineralizing agent is hydrogen fluoride.

8. The method of claim 1 wherein the growth medium additionally comprises water.

9. The method of claim 8 wherein the molar ratio of water to Ti+Si is less than or equal to 10.

10. The method of claim 1 wherein the growth medium is characterized by the absence of a quaternary ammonium salt.

11. A non-hydrothermal method of making titanium silicalite comprising:

(i) preparing a precursor mixture comprised of

(a) a tetraalkylorthosilicate;

(b) a titanium alkoxide;

(c) a growth medium comprising water, a nitrogen-containing, organic base selected from the group consisting of primary alkylamines, secondary alkylamines, tertiary alkylamines, N-heterocycles and mixtures thereof, hydrogen fluoride, and, optionally, an organic solvent which does not inhibit mineralization of the tetraalkylorthosilicate and titanium alkoxide wherein such growth medium is characterized by the absence of a quaternary ammonium salt; and

(ii) heating said precursor mixture at a temperature of from 100°

C. to 200°

C. for a time effective to form as-synthesized titanium silicalite.

12. The method of claim 11 wherein the tetraalkyl orthosilicate is tetraethylorthosilicate.

13. The method of claim 11 wherein the titanium alkoxide is titanium tetra- n-butoxide.

14. The method of claim 11 wherein said precursor mixture is prepared by first combining the nitrogen-containing organic base, tetraalkylorthosilicate, and titanium alkoxide to form an initial mixture and then combining hydrogen fluoride and, optionally, water with said initial mixture.

15. The method of claim 11 comprising the additional step of calcining the as-synthesized titanium silicalite.

16. The method of claim 11 wherein the nitrogen-containing organic base is a N-heterocycle.

17. The method of claim 16 wherein the N-heterocycle is hexamethyleneimine.

18. The method of claim 11 comprising the additional step of washing the as-synthesized titanium silicalite with dilute aqueous acid.

19. The method of claim 11 wherein the growth medium contains water in an amount such that the molar ratio of water to Ti+Si is from 1:

1 to 10;

1.

20. The method of claim 11 wherein the molar ratio of fluoride to Ti+Si in is in the range of 0.5 to 5.

21. The method of claim 11 wherein the molar ratio of Si to Ti is in the range of from 4:

1 to 50;

1.

22. The method of claim 11 wherein the precursor mixture is seeded with crystals of titanium silicalite.