Molecular sieve adsorbent for gas purification and preparation thereof

• US 6,530,975 B2
• Filed: 01/19/2001
• Issued: 03/11/2003
• Est. Priority Date: 07/01/1998
• Status: Expired due to Fees

• Current Assignee: Zeochem
• Original Assignee: Zeochem
• Inventors: Rode, Edward J., Tsybulevskiy, Albert M.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US09/766,185
• Publication Number:
  US 20010049998A1
• Time in Patent Office: 781 Days
• Field of Search: 951/17, 951/39, 959/02, 961/08, 502/68, 502/79
• US Class Current: 95/117
• CPC Class Codes: B01J 20/183 Physical conditioning without chemical treatment, e.g. drying, granulating, coating, irradiation
• CPC Class Codes: B01J 20/186 Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y10S 95/902 Molecular sieve

Abstract

A molecular sieve adsorbent for the purification of gas streams containing water vapor and carbon dioxide. The adsorbent is a combination of sodium form of a low-silica faujasite, having a residual content of potassium ions less than about 8.0 percent (equiv.), a low content of crystalline and amorphous admixtures and crystal sizes generally within the range of 1-4 μm, and a binder. A process for the adsorbent preparation which comprises specific parameters of low silica faujasite synthesis, sodium-potassium ion exchange, blending and granulation.

Claims

1. A molecular sieve adsorbent for gas purification which comprises a sodium form of low-silica faujasite, having a silica:

alumina ratio of about 1.8-2.2 with a residual content of potassium ions less than about 8.0 percent (equiv.), and a binder, wherein at least about 80% of said low-silica faujasite by weight has a crystal size in the range of 1-4 μ

m.

2. The molecular sieve adsorbent of claim 1 wherein the silica to alumina ratio is about 2.0 to about 2.2.

3. The molecular sieve adsorbent of claim 1 wherein the silica to alumina ratio is about 2.0 to about 2.1.

4. The molecular sieve adsorbent of claim 1 wherein the residual content of potassium ions is less than about 2.5 percent (equiv.).

5. The molecular sieve adsorbent of claim 1 wherein the residual content of potassium ions is less than about 1.0 percent (equiv.).

6. The molecular sieve adsorbent of claim 1 wherein the low silica faujasite comprises from about 60 to about 85 percent and the binder comprises from about 15 to about 40 percent of the adsorbent.

7. The adsorbent of claim 1 wherein the low-silica faujasite comprises less than 10.0 percent by weight zeolite A, high silica faujasite X and other crystalline and amorphous admixtures.

8. The adsorbent of claim 1 wherein the low-silica faujasite comprises less than 2.0 percent by weight zeolite A, high silica faujasite X and other crystalline and amorphous admixtures.

9. The adsorbent of claim 1, wherein the crystal size of at least about 80 percent of the low-silica faujasite is in the range of about 1-3 μ

m.

10. The adsorbent of claim 1, wherein the crystal size of at least about 80 percent of the low-silica faujasite is in the range of about 1-2 μ

m.

11. The adsorbent of claim 1, wherein the binder is selected from the group consisting of kaolinite, bentonite, montmorillonite, and attapulgite clays, silica, alumina, alumosilicates, and cements.

12. The adsorbent of claim 1, wherein the adsorbent has a volume of macropores with a radius from about 1000 to 10000 Å

from about 0.3 to about 0.5 cm³/g.

13. The molecular sieve adsorbent of claim 1 wherein the low silica faujasite has a volume of macropores with a radius from about 1000 to 10000 Å

of at least about 0.3 cm³/g.

14. A process for the adsorption of carbon dioxide and water from a gas stream comprising

passing the gas stream containing carbon dioxide and water over the molecular sieve adsorbent of claim 1, whereby substantial quantities of the carbon dioxide and water are adsorbed by the molecular sieve adsorbent.

15. A molecular sieve adsorbent for gas purification which comprises a sodium form of low-silica faujasite, having a silica:

alumina ratio of about 1.8-2.2 with a residual content of potassium ions less than about 8.0 percent (equiv.), and a binder, wherein the adsorbent has a volume of macropores with a radius from about 1000 to 10,000 Å

of at least about 0.3 cm³/g.

16. A molecular sieve adsorbent for gas purification which comprises a sodium form of low-silica faujasite, having a silica:

alumina ratio of about 1.8-2.2 with a residual content of potassium ions less than about 8.0 percent (equiv.), and a binder, wherein at least about 80% of said low-silica faujasite by weight has a crystal size in the range of 1-4 μ

m and wherein the adsorbent has a volume of macropores with a radius from about 1000 to 10,000 Å

of at least about 0.3 cm³/g.

17. A process for the production of a molecular sieve adsorbent comprising

preparing a sodium form of a low-silica faujasite, wherein the low-silica faujasite has a silica:

alumina ratio of about 1.8 to about 2.2 and a residual content of potassium ions less than about 8.0 percent (equiv.), wherein at least about 80 percent of the low-silica faujasite by weight has a crystal size in the range of 1-4 μ

m;

blending the resultant product with a binder and a peptizer;

forming the blended product into a shaped article; and

drying and calcining the article to produce the adsorbent product.

18. The process of claim 17 wherein the low-silica faujasite is prepared by mixing sodium aluminate, sodium silicate and sodium and potassium hydroxide, wherein the ratio of the components expressed as mixtures of oxide are within the following ranges:

19. The process of claim 17 further comprising mixing a powder of montmorillonite in the amount of about 0.6 to about 1.5 percent, based on the final weight of the reaction product, with the prepared low silica faujasite into a reaction mixture under intensive stirring for about 15 to 30 minutes.

20. The process of claim 17 further comprising ion exchanging the prepared, sodium form of low-silica faujasite with a sodium chloride solution.

21. The process of claim 20 wherein the sodium form of low silica faujasite is ion exchanged from about 1 to about 3 times.

22. The process of claim 20 wherein the sodium form of low silica faujasite is ion exchanged at a temperature from about 60°

C. to about 85°

C.

23. The process of claim 17 further comprising ion exchanging the prepared, sodium form of low-silica faujasite with a solution comprising sodium chloride and sodium hydroxide.

24. The process of claim 17 further comprising treating the prepared sodium form of low-silica faujasite and binder with a pore-forming additive.

25. The process of claim 24 wherein the pore-forming additive is selected from the group consisting of synthetic and natural materials including mineral acids, polyalkeneglycols, polyacrylamides, polycarboxylates, starch, molasses and lignin.

26. The process of claim 25 wherein the peptizer and pore-forming additives comprise from about 0.5 to about 2.0 percent of the adsorbent product, based on a total weight of the adsorbent product.

27. The process of claim 17 further comprising blending the low-silica faujasite with a peptizer prior to mixing with the binder.

28. The process of claim 17 further comprising blending the binder with the peptizer prior to mixing with the low silica faujasite.