Process for preparing iron(III)-exchanged zeolite composition

Patent metadata

Field	Value
Publication number	US-10710059-B2
Application number	US-201616062364-A
Country	US
Kind code	B2
Filing date	Dec 20, 2016
Priority date	Dec 22, 2015
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

The present disclosure relates to processes for formation of a molecular sieve, particularly a metal-promoted molecular sieve, and more particularly an Iron(III) exchanged zeolite. Preferably, the zeolite is of the chabazite form or similar structure. The processes can include combining a zeolite with Iron(III) cations in an aqueous medium. The process can be carried out at a pH of less than about 7, and a buffering material can be used with the aqueous medium. The processes beneficially result in Iron exchange that can approach 100% along with removal of cations (such as sodium, NH4, and H) from the zeolite. An Iron(III)-exchanged zeolite prepared according to the disclosed processes can include about 2,000 ppm or less of cation and about 1% by weight or greater of Iron(III). The disclosure also provides catalysts (e.g., SCR catalysts) and exhaust treatment systems including the Iron(III)-exchanged zeolite.

First claim

The invention claimed is:

1. A process for preparing an Iron-exchanged zeolite, the process comprising combining a zeolite with Iron(III) cations in an aqueous medium such that the Iron(III) cations are exchanged into or onto the zeolite to thus form an Iron(III)-exchanged zeolite;
wherein the zeolite and the Iron(III) cations are combined in an aqueous medium that comprises a buffering agent and that is at a pH of about 2.0 to about 6.0.

2. The process of claim 1 , wherein the zeolite has a double 6-ring (D6R) building unit structure.

3. The process of claim 1 , wherein the zeolite has a chabazite (CHA) structure.

4. The process of claim 1 , wherein the Iron(III) cations are provided from an Iron(III) salt.

5. The process of claim 4 , wherein the Iron(III) salt is selected from the group consisting of Iron(III) halides, Iron(III) citrates, Iron(III) nitrates, Iron(III) sulfates, Iron(III) acetate, and combinations thereof.

6. The process of claim 5 , wherein the Iron(III) salt is selected from the group consisting of Iron(III) nitrates, Iron(III) sulfates, and combinations thereof.

7. The process of claim 1 , wherein the Iron(III) cations are provided in situ via oxidation of an Iron(II) salt.

8. The process of claim 1 , wherein the Iron(III) cations are exchanged with one or more different cations present in or on the zeolite such that about 75% by weight or greater of the different cations present in or on the zeolite are exchanged with the Iron(III) cations.

9. The process of claim 1 , wherein the Iron(III)-exchanged zeolite comprises Iron(III) in an amount of about 1% by weight or greater.

10. The process of claim 9 , wherein the Iron(III)-exchanged zeolite comprises Iron(III) in an amount of about 1% by weight to about 10% by weight.

11. The process of claim 1 , wherein the Iron(III)-exchanged zeolite comprises sodium, NH 4 , or H cations in an amount of about 2,000 ppm or less.

12. The process of claim 1 , wherein the pH is about 3.0 to about 5.0.

13. The process of claim 1 , wherein the buffering agent comprises ammonium acetate.

14. The process of claim 1 , wherein the exchange of Iron(III) into or onto the zeolite is carried out at a temperature that is greater than about 30° C. and is less than the decomposition temperature of an Iron salt that is included in the aqueous medium as a source for the Iron(III) cations.

15. The process of claim 1 , wherein the exchange of Iron(III) cations into or onto the zeolite is carried out at a temperature of about 30° C. to about 80° C.

16. The process of claim 1 , wherein the exchange of Iron(III) cations into or onto the zeolite is carried out at a temperature of about 40° C. to about 70° C.

17. The process of claim 1 , wherein the process results in substantially no ammonium nitrate formation.

18. The process of claim 1 , wherein the process further comprises washing and filtering the Iron(III)-exchanged zeolite to a solution conductivity of about 200 micromhos or less.

Assignees

• Basf Corp

Inventors

• Fu Qi
• Slawski Barbara
• Pfab Peter

Classifications

• C01B39/02 Primary

  Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof · CPC title

• B01J29/723 Primary

  CHA-type, e.g. Chabazite, LZ-218 · CPC title

• B01D53/9418 Primary

  for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas · CPC title

• B01D46/0027

  with additional separating or treating functions · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title