Method for producing metal exchanged zeolites by solid-state ion exchange at low temperatures
Method for the preparation of a metal-exchanged zeolites or mixtures of metal-exchanged zeolites, such as Cu-SSZ-13, Cu-ZSM-5, Cu-beta, or Fe-beta, comprising the steps of providing a dry mixture of a) one or more microporous zeotype materials that exhibit ion exchange capacity and b) one or more metal compounds; heating the mixture in a gaseous atmosphere containing ammonia to a temperature lower than 300° C. for a time sufficient to initiate and perform a solid state ion exchange of ions of the metal compound and ions of the zeolite material; and obtaining the metal-exchanged zeolite material.
1. Method for the preparation of a metal-exchanged zeolite material or mixtures of metal-exchanged zeolites materials comprising the steps of providing a dry mixture containing a) one or more zeolites starting materials that exhibit ion exchange capacity and b) one or more metal compounds; heating the mixture in a gaseous atmosphere containing ammonia at a temperature of between 150° C. and 250° C. to perform a solid state ion exchange of ions of the metal compound and ions of the one or more zeolites; and obtaining the metal-exchanged zeolite material or the mixture of metal-exchanged zeolite materials, wherein the metal compound is Cu (I) oxide.
2. Method according to claim 1 , wherein the one or more zeolite starting materials have the framework code of AEI, AFX, CHA, KFI, LTA, IMF, ITH, MEL, MFI, SZR, TUN, *BEA, BEC, FAU, FER, MOR, LEV.
3. Method according to claim 1 , wherein the one or more zeolite starting materials are selected from the group consisting of ZSM-5, zeolite Y, beta zeolite, SSZ-13, SSZ-39, SSZ-62, and Chabazite.
4. Method according to claim 1 , wherein the one or more zeolite starting materials are in the H + or NH 4 + form.
5. Method according to claim 1 , wherein the one or more zeolite starting materials contain an organic structure directing agent.
6. Method according to claim 1 , wherein the one or more metal compounds are selected from the group of metal oxides, metal nitrates and phosphates, sulfates, oxalates, acetates or combinations thereof.
7. Method according to claim 1 , wherein the content of ammonia in the atmosphere is between 1 and 5000 vol. ppm.
8. Method according to claim 1 , wherein the content of oxygen in the atmosphere is 10% or lower.
9. Method according to claim 1 , wherein the content of water in the atmosphere is 5 vol. % water or less.
10. Method according to claim 1 , wherein the mixture of one or more zeolites starting materials that exhibit ion exchange capacity and one or more metal compounds is heated in the gaseous atmosphere containing ammonia at a temperature of between 150° C. and 250° C.
11. A metal-exchanged zeolite or mixtures of metal-exchanged zeolites obtained by a method according to claim 1 .
12. A method for the removal of nitrogen oxides from exhaust gas by selective catalytic reduction with a reductant, comprising contacting the exhaust gas with a catalyst comprising a metal-exchanged zeolite or mixtures of metal-exchanged zeolites obtained by a method according to claim 1 .
13. A method according to claim 12 , wherein the reductant is ammonia or a precursor thereof.
14. A method according to claim 12 , wherein the reductant comprises hydrocarbons.