Porous ceramic composition, filter, and articles
The present disclosure relates to porous ceramic compositions and porous ceramic articles, such as honeycomb structure bodies and porous ceramic filters. In various embodiments, a particulate filter is disclosed herein; in some of these embodiments, the particulate filter is a gasoline particulate filter (GPF) and is suitable for use with a gasoline engine and treating its exhaust, and in some of the embodiments, the particulate filter is a diesel particulate filter (DPF) and is suitable for use with a diesel engine and treating its exhaust.
1. A particulate filter comprised of at least one porous ceramic wall, the wall comprising a microstructure comprising:
average bulk porosity >62% as measured by mercury porosimetry,
d10>10 μm,
d50>16 μm,
df<0.40,
d90<37 μm, and
surface porosity at the surface of the wall as measured by x-ray tomography is within 10% of an average mid-web porosity of the middle 30% of the wall, and wherein a minimum porosity measured at any point from the surface of the wall and perpendicularly into the wall to within 15 μm of the surface of the wall is at least 90% of the average porosity of the middle 30%.
2. The filter of claim 1 wherein the average bulk porosity as measured by mercury porosimetry is between 62 and 68%, inclusive.
3. The filter of claim 1 wherein d50 is between 17-20 μm, inclusive.
4. The filter of claim 1 wherein d90<35 μm.
5. The filter of claim 1 wherein d90<30 μm.
6. The filter of claim 1 wherein d90 is between 25-37 μm, inclusive.
7. The filter of claim 1 wherein the surface porosity as measured by x-ray tomography which is within 5% of the bulk porosity at midpoint of the wall.
8. The filter of claim 1 wherein the surface porosity as measured by x-ray tomography differs from the bulk porosity at midpoint of the wall by less than 10%.
9. The filter of claim 1 wherein the microstructure comprises d10>11 μm.
10. The filter of claim 1 wherein the filter further comprises a washcoat material disposed at least partially within the wall.
11. The filter of claim 10 wherein the washcoat material is comprised of three-way catalyst TWC material, SCR material, or a combination thereof.
12. The filter of claim 10 wherein the washcoat-loaded filter has a CTE which is within 10% of the uncoated porous ceramic wall.
13. The filter of claim 10 wherein the washcoat material is present with a washcoat loading of >30 g/l.
14. The filter of claim 10 wherein the washcoat material is present with a washcoat loading of >50 g/l.
15. The filter of claim 10 wherein the washcoat material is present with a washcoat loading of >75 g/l.
16. The filter of claim 10 wherein the washcoat material is present with a washcoat loading of between 30 and 120 g/l.
17. The filter of claim 10 wherein the washcoat material is present with a washcoat loading of between 50 and 120 g/l.
18. The filter of claim 10 wherein the washcoat material is present with a washcoat loading of between 75 and 120 g/l.
19. The filter of claim 1 further comprising all of the washcoat material disposed below the surface of the porous ceramic wall.
20. The filter of claim 1 wherein the porous ceramic wall has a (d50-d10)/d50<0.40.
21. The filter of claim 1 wherein the porous ceramic wall has a (d90-d50)/d50<1.15.
22. The filter of claim 1 wherein the porous ceramic wall has a wall thickness >40 μm.
23. The filter of claim 1 wherein the filter comprises a matrix of porous ceramic walls.
24. The filter of claim 1 wherein the filter comprises a honeycomb matrix of porous ceramic walls.
25. A honeycomb filter body comprised of at least one porous ceramic wall, the wall comprising a microstructure comprising:
total porosity 63-67% as measured by mercury porosimetry,
d50 of 16 to 19 μm, inclusive,
d90<37 μm,
df<0.40 and
surface porosity at the surface of the wall as measured by x-ray tomography is within 10% of an average mid-web porosity of the middle 30% of the wall, and wherein a minimum porosity measured at any point from the surface of the wall and perpendicularly into the wall to within 15 μm of the surface of the wall is at least 90% of the average porosity of the middle 30%.
26. The honeycomb filter body of claim 25 wherein the minimum porosity measured at any point from the surface of the wall and perpendicularly into the wall to within 15 μm of the surface of the wall is at least 95% of the average porosity of the middle 30%.
27. The filter of claim 1 wherein the minimum porosity measured at any point from the surface of the wall and perpendicularly into the wall to within 15 μm of the surface of the wall is at least 95% of the average porosity of the middle 30%.