SILICON-TITANIUM MIXED OXIDE-CONTAINING DISPERSION FOR THE PRODUCTION OF TITANIUM-CONTAINING ZEOLITES

• US 20090137827A1
• Filed: 03/12/2007
• Published: 05/28/2009
• Est. Priority Date: 04/15/2006
• Status: Abandoned Application

• Current Assignee: Evonik Degussa GmbH
• Original Assignee: Evonik Degussa GmbH
• Inventors: Lortz, Wolfgang, Schumacher, Kai
• Application Number:
  US12/294,371
• Publication Number:
  US 20090137827A1
• Time in Patent Office: Days
• US Class Current: 549/529
• CPC Class Codes: B01J 29/89 Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium B01J29/005 takes precedence
• CPC Class Codes: C01B 33/14 Colloidal silica, e.g. dispersions, gels, sols
• CPC Class Codes: C01B 33/183 by oxidation or hydrolysis in the vapour phase of silicon compounds such as halides, trichlorosilane, monosilane
• CPC Class Codes: C01B 37/005 Silicates, i.e. so-called metallosilicalites or metallozeosilites
• CPC Class Codes: C01B 39/085 Group IVB- metallosilicates
• CPC Class Codes: C07D 301/12 with hydrogen peroxide or inorganic peroxides or peracids

Abstract

Dispersion containing pyrogenic silicon-titanium mixed oxide powders with a silicon dioxide content of 75 to 99.99 wt.-% and a titanium dioxide content of 0.01 to 25 wt. %, water and a basic, quaternary ammonium compound, wherein the mean aggregate diameter of the particles of the silicon-titanium mixed oxide powder in the dispersion is 200 nm at most. Process for the production of a titanium-containing zeolite with the use of the dispersion.

Claims

1. :

A dispersion comprising pyrogenic silicon-titanium mixed oxide powder with a silicon dioxide content of 75 to 99.99 wt % and a titanium dioxide content of 0.01 to 25 wt %,

water and

a basic, quaternary ammonium compound,

wherein the mean aggregate diameter of particles of the silicon-titanium mixed oxide powders in the dispersion is 200 nm at most.

2. :

The dispersion according to claim 1, wherein a mean aggregate diameter is less than 100 nm.

3. :

The dispersion according to claim 1, wherein a BET surface area of the pyrogenic silicon-titanium mixed oxide powder is 10 to 400 m²/g.

4. :

The dispersion according to claim 1, wherein said dispersion comprises at most 50 ppm of each of Na, K, Fe, Co, Ni, Al, Ca and Zn.

5. :

The dispersion according to claim 1, wherein the quaternary, basic ammonium compound is a tetralkylammonium hydroxide selected from the group consisting of tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, and tetra-n-butylammonium hydroxide.

6. :

The dispersion according to claim 1, wherein a mole water to mole silicon-titanium mixed oxide ratio ranges from 10 to 20.

7. :

The dispersion according to claim 1, wherein a pH value is 9 to 11.

8. :

The dispersion according to claim 1, wherein a mole ammonium compound to mole silicon-titanium mixed oxide ratio ranges from 0.12 to 0.20.

10. :

A process for the production of a titanium-containing zeolite, comprising processing at a temperature of 150 to 220°

.C for a time period of less than 12 hours the dispersion according to claim 1.

11. :

The process according to claim 10, further comprising separating, drying and calcinating the titanium-containing zeolite.

12. :

A titanium-containing zeolite obtained through the process according to claim 10.

13. :

A process for epoxidizing olefins comprising reacting an olefin with hydrogen peroxide in the presence of a titanium-containing zeolite according to claim 12, wherein said zeolite is a catalyst.

14. :

The process according to claim 10, wherein the dispersion further comprises a basic, quaternary ammonium compound.

15. :

A process for producing a dispersion according to claim 1, said process comprising;

(1) circulating water from a holding tank through a rotor/stator machine;

(2) introducing silicon-titanium mixed oxide powder into a shear zone, thereby forming a predispersion with a solids content of 20 to 40 wt %, where said shear zone is situated between grooves of rotor teeth and stator grooves;

(3) continually shearing said predispersion at a shear rate ranging from 10,000 to 40,000 sec<sup>−

1</sup>; and

(4) adding a basic, quaternary ammonium compound;

wherein, when the pH of said water in (1) is altered to less than 2 or greater than 4 by said introducing in (2), said pH is adjusted by adding an acid or a base.

16. :

The process according to claim 15, wherein (4) further comprises adding water.

9. :

A process for the production of the dispersion according to claim comprising;

water, which, in the event that the silicon-titanium mixed oxide powder incorporated later leads to a pH value of the aqueous phase of <

2 or >

4, is adjusted to pH values of 2 to 4 by addition of acids or bases, is circulated from a holding tank through a rotor/ stator machine, and

via a filling device, silicon-titanium mixed oxide powder is continuously or discontinuously introduced into the shear zone between the grooves of the rotor teeth and the stator groove, with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of 20 to 40 wt % results, and

after all the silicon-titanium mixed oxide powder has been added, the filling device is closed, and shearing continued such that the shear rate lies in the range between 10000 to 40000 sec<sup>−

1</sup>, and next, while maintaining the dispersing conditions, a basic, quaternary ammonium compound and optionally water, before the addition of the ammonium compound, are added.