Photocatalyst having an x-ray diffraction pattern which is substanially free of characteristic reflections associated with crystalline TiO.sub.2

• US 5,981,426 A
• Filed: 08/29/1997
• Issued: 11/09/1999
• Est. Priority Date: 03/02/1995
• Status: Expired due to Fees

• Current Assignee: University Technologies International, Inc.
• Original Assignee: University Technologies International, Inc.
• Inventors: Xu, Yiming, Langford, Cooper H.
• Primary Examiner(s): Lewis, Michael
• Assistant Examiner(s): Ghyka, Alexander G.
• Application Number:
  US08/920,357
• Time in Patent Office: 802 Days
• Field of Search: 502/4, 502/5, 502/60, 502/305, 502/309, 502/350
• US Class Current: 502/309
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: C02F 1/32 with ultraviolet light

Abstract

A photocatalyst compound comprising: (i) a photocatalyst selected from the group consisting of TiO₂, WO₃ and mixtures thereof, the photocatalyst being substantially free of sharp, narrow band X-ray reflections at angles corresponding those of crystalline TiO₂, WO₃ and mixtures thereof, and (ii) a porous, crystalline, adsorbent support material. A process for producing the photocatalyst compound is also disclosed. The process comprises: (i) hydrolysing a non-ionic titanium compound to produce a colloidal suspension having an average particle size of less than about 250 Å; (ii) contacting a porous, crystalline, adsorbent support material with the colloidal suspension to produce an impregnated support; and (iii) calcining the impregnated support to produce the photocatalyst compound. The photocatalyst compound is useful, in the treatment of a fluid containing an organic pollutant.

Claims

1. A photocatalyst compound comprising:

(i) a photocatalyst selected from the group consisting of TiO₂, WO₃ and mixtures thereof, the photocatalyst having an X-ray diffraction pattern which is substantially free of characteristic reflections associated with crystalline TiO₂, WO₃ and mixtures thereof, and (ii) a porous, crystalline, adsorbent support material having a crystallinity of at least about 50%.

2. The photocatalyst compound defined in claim 1, wherein the photocatalyst is TiO₂.

3. The photocatalyst compound defined in claim 1, wherein the support material has a crystallinity of at least about 60%.

4. The photocatalyst compound defined in claim 2, wherein the support material has a crystallinity of at least about 70%.

5. The photocatalyst compound defined in claim 2, wherein the support material has a crystallinity of at least about 85%.

6. The photocatalyst compound defined in claim 1, wherein the support material has an average pore size in the range of from about 5 Å

to about 15 Å

.

7. The photocatalyst compound defined in claim 1, wherein the support material has an average pore size in the range of from about 5 Å

to about 12 Å

.

8. The photocatalyst compound defined in claim 1, wherein the support material is zeolite.

9. The photocatalyst compound defined in claim 1, wherein the support material is a hydrophobic zeolite.

10. The photocatalyst compound defined in claim 2, wherein support material is a hydrophobic zeolite comprising a silicon to aluminum weight ratio in the range of from about 10:

1 to about 100;

1.

11. The photocatalyst compound defined in claim 2, wherein the zeolite is selected from the group consisting of ZSM5, Zeolite A and mixtures thereof.

12. The photocatalyst compound defined in claim 1, wherein the photocatalyst further comprises up to about 5% by weight, based on the total weight of photocatalyst, of at least one transition metal of the Periodic Table.

13. The photocatalyst compound defined in claim 1, wherein the photocatalyst further comprises up to about 2% by weight, based on the total weight of photocatalyst of at least one transition metal of the Periodic Table.

14. The photocatalyst compound defined in claim 1, wherein the photocatalyst further comprises up to about 2% by weight of at least one transition metal selected from the fourth period of the Periodic Table.

15. The photocatalyst compound defined in claim 12, wherein the transition metal is selected from the group consisting of titanium, iron, vanadium, chromium and mixtures thereof.

16. The photocatalyst compound defined in claim 1, wherein the support material is a molecular sieve.

17. The photocatalyst compound defined in claim 1, wherein the support material is a molecular sieve selected from the group consisting of titanium silicates, aluminum phosphates, members of the MCM family and mixtures thereof.

18. The photocatalyst compound defined in claim 2, wherein the TiO₂ is present in an amount of from about 0.5% to about 10% by weight of the photocatalyst compound.

19. The photocatalyst compound defined in claim 2, wherein the TiO₂ is present in an amount of from about 2% to about 8% by weight of the photocatalyst compound.

20. The photocatalyst compound defined in claim 2, wherein the TiO₂ is present in an amount of from about 2% to about 6% by weight of the photocatalyst compound.

21. A process for producing a photocatalyst compound comprising the steps of:

(i) hydrolysing a non-ionic titanium compound to produce a colloidal suspension having an average particle size of less than about 250 Å

;

(ii) contacting a porous, crystalline, adsorbent support material with the colloidal suspension to produce an impregnated support; and

(iii) calcining the impregnated support to produce a photocatalyst compound comprising a TiO₂ photocatalyst, the photocatalyst having an X-ray diffraction pattern which is substantially free of characteristic reflections associated with crystalline TiO₂.

22. The process defined in claim 21, wherein the non-ionic titanium compound is selected from the group consisting of TiCl₄, Ti(OR)₄ and mixtures thereof, wherein R is a C₁ -C₁₀ alkyl group.

23. The process defined in claim 22, wherein R is propyl.

24. The process defined in claim 21, wherein, prior to Step (i), the non-ionic titanium compound is dissolved in a water-miscible organic solvent.

25. The process defined in claim 21, wherein the colloidal suspension has an average particle size in the range of from about 20 Å

to about 100 Å

.

26. The process defined in claim 21, wherein the colloidal suspension has an average particle size in the range of from about 20 Å

to about 75 Å

.

27. The process defined in claim 21, wherein Step (ii) is conducted with mixing.

28. The process defined in claim 21, wherein Step (ii) is conducted for a period of at about 1 hour.

29. The process defined in claim 21, wherein Step (ii) further comprises air drying the impregnated support at a temperature in the range of from about 20°

to about 150°

C.

30. The process defined in claim 21, wherein Step (iii) comprises calcining the impregnated support at a temperature in the range of from about 250°

to about 500°

C. for a period of at least about 12 hours.

31. A photocatalyst compound comprising:

(i) a TiO₂ photocatalyst, the photocatalyst having an X-ray diffraction pattern which is substantially free of characteristic reflections associated with crystalline TiO₂, and (ii) a porous, crystalline, adsorbent zeolite support material having a crystallinity of at least about 100%,

wherein the photocatalyst is present;

(a) in an amount in the range of from about 0.5% to about 10% by weight based on the weight of the photocatalyst compound; and

(b) as a layer which substantially completely covers the external surface of the adsorbent zeolite support material.

32. The photocatalyst compound defined in claim 31, wherein the support material has a crystallinity of at least about 85%.

33. The photocatalyst compound defined in claim 31, wherein the support material has an average pore size in the range of from about 5 Å

to about 12 Å

.

34. The photocatalyst compound defined in claim 31, wherein support material is a hydrophobic zeolite comprising a silicon to aluminum weight ratio in the range of from about 10:

1 to about 100;

1.

35. The photocatalyst compound defined in claim 31, wherein the zeolite is selected from the group consisting of ZSM5, Zeolite A and mixtures thereof.

36. The photocatalyst compound defined in claim 31, wherein the TiO₂ is present in an amount of from about 2% to about 8% by weight of the photocatalyst compound.

37. The photocatalyst compound defined in claim 31, wherein the TiO₂ is present in an amount of from about 2% to about 6% by weight of the photocatalyst compound.