Honeycomb catalytic article
There is provided a honeycomb structure where a catalyst is loaded on surfaces of inner pores of the surface layer and on a surface of the surface layer; a relation between a catalyst area proportion A of the catalyst to a gap area proportion B of a gap in a cross-section of the surface layer on the inlet side is 1%<A/B<90%; and a relation between an average catalyst area proportion, A 1 , from the surface to a point having a depth of one third of the thickness of the surface layer including the surface of the surface layer on the inlet side and a catalyst area proportion A 2 in a central portion of the surface layer is A 1 /A 2 >1.5.
1. A honeycomb catalytic article comprising partition walls having:
a porous partition wall matrix separating and forming a plurality of cells functioning as fluid passages, and
a surface layer provided on only the inflow side or each of the inflow side and the outflow side of the partition wall matrix;
with predetermined cells each of which has an open end portion on one side and a plugged end portion on the other side and remaining cells each of which has a plugged end portion on the one side and an open end portion on the other side being alternately disposed, and a catalyst being loaded on surfaces of inner pores of the surface layer and on a surface of the surface layer;
wherein a relation between a catalyst area proportion A of the catalyst to a gap area proportion B of a gap in a cross-section of the surface layer on the inlet side is 1%<A/B<90% in a central portion in a thickness direction of the surface layer, and
a relation between an average catalyst area proportion Al from the surface to a point having a depth of one third of the thickness of the surface layer including the surface of the surface layer on the inlet side and a catalyst area proportion A 2 in a central portion of the surface layer is A 1 /A 2 >1.5.
2. A honeycomb catalytic article according to claim 1 , wherein A and B satisfy 5%<A/B<50% in the central portion in a thickness direction of the surface layer on the inlet side.
3. A honeycomb catalytic article according to claim 2 , wherein A satisfy 5%<A<80% in an image shot from the direction perpendicular to the surface of the surface layer on the inlet side.
4. A honeycomb catalytic article according to claim 3 , wherein the surface layer has a peak pore size, constituting a peak of a pore distribution after loading of a catalyst, of 0.3 μm or more and below 10 μm and a porosity of 40% or more and below 95%.
5. A honeycomb catalytic article according to claim 4 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
6. A honeycomb catalytic article according to claim 3 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
7. A honeycomb catalytic article according to claim 2 , wherein the surface layer has a peak pore size, constituting a peak of a pore distribution after loading of a catalyst, of 0.3 μm or more and below 10 μm and a porosity of 40% or more and below 95%.
8. A honeycomb catalytic article according to claim 7 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
9. A honeycomb catalytic article according to claim 2 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
10. A honeycomb catalytic article according to claim 1 , wherein A satisfy 5%<A<80% in an image shot from a direction perpendicular to the surface of the surface layer on the inlet side.
11. A honeycomb catalytic article according to claim 10 , wherein the surface layer has a peak pore size, constituting a peak of a pore distribution after loading of a catalyst, of 0.3 μm or more and below 10 μm and a porosity of 40% or more and below 95%.
12. A honeycomb catalytic article according to claim 11 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
13. A honeycomb catalytic article according to claim 10 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
14. A honeycomb catalytic article according to claim 1 , wherein the surface layer has a peak pore size, constituting a peak of a pore distribution after loading of a catalyst, of 0.3 μm or more and below 10 μm and a porosity of 40% or more and below 95%.
15. A honeycomb catalytic article according to claim 14 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
16. A honeycomb catalytic article according to claim 1 , wherein the thickness L 1 of the surface layer is 3% or more and below 15% of the thickness L 2 of the partition walls.
17. A honeycomb catalytic article according to claim 1 , wherein the partition wall matrix has an average pore size of 9 μm or more and below 60 μm and a porosity of 28% or more and below 50%.
18. A honeycomb catalytic article according to claim 1 , wherein the partition wall matrix contains at least one kind selected from the group consisting of cordierite, Si-bonded SiC, recrystallized SiC, aluminum titanate, mullite, silicon nitride, sialon, zirconium phosphate, zirconia, titania, alumina, and silica as a main component.
19. A honeycomb catalytic article according to claim 1 , wherein the partition wall matrix and the surface layer contain the same material as a main component.
20. A honeycomb catalytic article according to claim 1 , wherein a catalyst containing one of or both platinum and palladium is loaded on the surface layer.