Surface-treated silicoaluminophosphate molecular sieve
A catalyst material for abatement of exhaust gas emissions from a lean burn engine is provided, the catalyst material including a metal-exchanged SAPO-34 material, and an oxide layer at least partially covering an outside surface of the SAPO-34 material, wherein the oxide layer is not substantially blocking the pores of the SAPO-34 material.
1. A catalyst material for abatement of exhaust gas emissions from a lean burn engine, the catalyst material comprising:
a metal-exchanged SAPO-34 material; and
an oxide layer at least partially covering an outside surface of the SAPO-34 material;
wherein the oxide layer is not blocking at least about 70% of the pores of the SAPO-34 material, and
wherein the oxide layer ranges from approximately 0.1 nm to about 50 nm in thickness.
2. The catalyst material of claim 1 , wherein the oxide layer comprises at least one of Al 2 O 3 , SiO 2 , ZrO 2 , and TiO 2 .
3. The catalyst material of claim 1 , wherein the oxide layer ranges from approximately 0.1 nm to 15 nm in thickness.
4. The catalyst material of claim 1 , wherein the metal is chosen from Cu, Fe, Co, Ce, Mn, and Ni.
5. The catalyst material of claim 1 , wherein the metal is Cu present at a loading ranging from 2% and 8% by weight.
6. A catalytic article comprising the catalyst material of claim 1 , in a washcoat deposited on a honeycomb substrate.
7. The catalytic article of claim 6 , wherein the honeycomb substrate comprises a wall flow filter substrate.
8. The catalytic article of claim 7 , wherein the honeycomb substrate comprises a flow through substrate.
9. An exhaust gas treatment system comprising the catalytic article of claim 6 disposed downstream from a diesel engine and a reductant source that adds a reductant to an exhaust gas stream from the engine.
10. A process for modifying a selective catalytic reduction catalyst material comprising a metal-exchanged SAPO-34 material, the process comprising:
using at least one cycle of a surface deposition method to deposit an oxide layer on at least a portion of an exposed outer surface of the SAPO-34 material, wherein the oxide layer does not substantially block the pores of the SAPO-34 material; and
wherein the modified selective catalytic reduction catalyst material is a catalyst material according to claim 1 .
11. The process of claim 10 , wherein the surface deposition method is chosen from-atomic layer deposition (ALD), chemical vapor deposition (CVD), particle vapor deposition (PVD), ion-beam assisted deposition (IBAD), and combinations thereof.
12. The process of claim 10 , wherein at least 60% of the exposed outer surface of the SAPO-34 material is coated with the oxide layer.
13. The process of claim 10 , wherein the oxide layer comprises one or more of Al 2 O 3 , SiO 2 , ZrO 2 , and TiO 2 .
14. The process of claim 10 , wherein the oxide layer deposited in the at least one cycle ranges from approximately 0.1 nm to about 1 nm in thickness.
15. The process of claim 10 , wherein 5 deposition cycles are used to deposit the oxide layer.
16. The process of claim 10 , wherein 10 deposition cycles are used to deposit the oxide layer.
17. The process of claim 10 , wherein the surface deposition method is run at a process temperature ranging from about 100° C. to about 250° C.
18. The process of claim 10 , wherein the surface deposition method is run at a process temperature ranging from about 120° C. to about 180° C.
19. The process of claim 10 , wherein the surface deposition method is run at a process temperature of about 150° C.
20. The process of claim 10 , wherein the metal is chosen from Cu, Fe, Co, Ce, Mn and Ni.
21. The process of claim 10 , wherein the metal is Cu present at a loading ranging from 2% and 8% by weight of the metal-exchanged SAPO-34 material.