Preparation of crystalline microporous and mesoporous metal silicates, products produced thereby and use thereof

• US 5,919,430 A
• Filed: 06/19/1997
• Issued: 07/06/1999
• Est. Priority Date: 06/19/1996
• Status: Expired due to Term

• Current Assignee: Evonik Degussa GmbH (Rag-Stiftung)
• Original Assignee: Degussa AG (Rag-Stiftung)
• Inventors: Roland, Eckehart, Scholz, Mario, Mangold, Helmut, Hasenzahl, Steffen, Thiele, Georg
• Primary Examiner(s): Bell, Mark L.
• Assistant Examiner(s): SAMPLE, DAVID R
• Application Number:
  US08/878,509
• Time in Patent Office: 747 Days
• Field of Search: 423/326, 423/328.2, 423/702, 423/704, 423/705, 423/707, 423/713, 423/712, 423/716, 423/717, 423/DIG. 22, 423/DIG. 27, 423/DIG. 29
• US Class Current: 423/702
• CPC Class Codes: B01J 29/04 having base-exchange properties, e.g. crystalline zeolites B01J29/005 takes precedence
• CPC Class Codes: B01J 29/86 Borosilicates; Aluminoborosilicates B01J29/005 takes precedence
• CPC Class Codes: B01J 29/89 Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium B01J29/005 takes precedence
• CPC Class Codes: C01B 37/00 Compounds having molecular sieve properties but not having base-exchange properties
• CPC Class Codes: C01B 37/005 Silicates, i.e. so-called metallosilicalites or metallozeosilites
• CPC Class Codes: C01B 39/065 Galloaluminosilicates; Group IVB- metalloaluminosilicates; Ferroaluminosilicates
• CPC Class Codes: C01B 39/12 the replacing atoms being at least boron atoms
• CPC Class Codes: C07D 301/12 with hydrogen peroxide or inorganic peroxides or peracids
• CPC Class Codes: Y10S 423/22 MFI, e.g. ZSM-5. silicalite, LZ-241
• CPC Class Codes: Y10S 423/27 Beta, e.g. NU-2
• CPC Class Codes: Y10S 423/29 MEL, e.g. ZSM-11

Abstract

Microporous and mesoporous metal silicates are prepared by the hydrothermal reaction of a silicon and metal source in the presence of a template. The choice of raw materials influences the purity and hence the catalytic activity of the products. A pyrogenic mixed oxide is used as the silicon and metal source. Prepared products have the composition (SiO₂)_1-x (A_m O_n)_x, where A is Ti, Al, B, V or Zr and x is 0.005 to 0.1. Shaped objects of the microporous and mesoporous metal silicates are obtained directly by using a shaped object of the pyrogenic mixed oxide. The products obtained are used as oxidation catalysts.

Claims

1. A process for the preparation of microporous and mesoporous metal silicates, comprising the hydrothermal reaction of a silicon and metal source in the presence of a template, wherein a pyrogenic metal-silicon mixed oxide is used as the silicon and metal source.

2. The process according to claim 1 for the preparation of crystalline microporous and mesoporous metal silicates of the general composition

3. The process according to claim 1 wherein said pyrogenic metal-silicon mixed oxide is prepared by flame hydrolysis.

4. The process according to claim 1 wherein said pyrogenic mixed oxide is selected from the group consisting of (SiO₂)_1-x (TiO₂)_x, (SiO₂)_1-x (Al₂ O₃)_x, (SiO₂)_1-x (B₂ O₃)_x, (SiO₂)_1-x (V₂ O₅)_x and (SiO₂)_1-x (ZrO₂)_x, in which x is 0.0001 to 0.25.

5. The process according to claim 1 wherein said template is an amine having one or more amino groups, an amino alcohol or a tetrasubstituted ammonium compound.

6. The process according to claim 1 wherein said template is tetraalkylammonium.

7. The process according to claim 1 wherein said template is used in an amount of 0.05 to 2.0 mol per mol of SiO₂ in the mixed oxide.

8. The process according to claim 1 further comprising that the hydrothermal reaction in the preparation of microporous metal silicates is carried out at a temperature from 100 to 220°

C.

9. The process according to claim 1 further comprising that the hydrothermal reaction in the preparation of microporous metal silicates is carried out at a temperature from 150 to 190°

C.

10. The process according to claim 1 wherein the preparation of mesoporous metal silicates is carried out at a temperature from 50 to 175°

C. under at least autogenous pressure.

11. The process according to claim 1 wherein the preparation of mesoporous metal silicates is carried out at a temperature from 70 to 150°

C. under at least autogenous pressure.

12. The process according to claim 1, wherein the pyrogenic mixed oxide is brought into contact with an aqueous solution containing hydroxyl ions and said template, the molar ratio of OH^- to SiO₂ being from 0.05 to 2.0.

13. The process according to claim 1 wherein said template compound is removed from the hydrothermal reaction by calcining from 300 to 1000°

C.

14. The process according to claim 1 wherein the pyrogenic metal-silicon mixed oxide is used in the form of a shaped object, the size and shape of the shaped objects remaining essentially unchanged in the hydrothermal reaction to give microporous and mesoporous metal silicates.

15. The process according to claim 14 wherein said pyrogenic metal-silicon mixed oxide is pore free.

16. The process according to claim 6 wherein said template is selected from the group consisting of tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide, and a microporous metal silicate with MFI, MEL or BEA structure is formed.

17. The process according to claim 6 wherein a template of structure RNR'"'"'₃⁺ X^- is used in which R stands for an alkyl group with at least 7 carbon atoms, R'"'"' stands for methyl or ethyl and X stands for hydroxide or a halide, and a mesoporous metal silicate with MCM-41 or MCM-48 structure is formed.

18. The process according to claim 14 wherein the shaped objects are formed by spray drying of a suspension consisting of the pyrogenic silicon metal mixed oxide and an aqueous solution of the template.

19. A process for the preparation of crystalline microporous titanium silicates of the general composition (SiO₂)_1-x (TiO₂)_x in which x is a number from 0.001 to 0.2 wherein a pyrogenic silicon-titanium mixed oxide is reacted with a tetraalkylammonium hydroxide template in a hydrothermal reaction at a temperature from 100 to 220°

C.

20. The process of claim 19, wherein the pyrogenic silicon-titanium mixed oxide is shaped to microgranules by a spray drying process prior to the hydrothermal reaction and a crystalline microporous titanium silicate in the form at microgranules is formed.