Methods of making honeycomb bodies having inorganic filtration deposits
Filtration articles herein exhibit excellent filtration efficiency and pressure drop before and after water durability testing. The articles comprise: a honeycomb filter body; inorganic deposits disposed within the honeycomb filter body at a loading of less than or equal to 20 grams of the inorganic deposits per liter of the honeycomb filter body. The inorganic deposits are comprised of refractory inorganic nanoparticles bound by a high temperature binder comprising one or more inorganic components. At least a portion of the inorganic deposits form a porous inorganic network over portions of inlet walls of the honeycomb filter body.
1. A filtration article comprising:
a honeycomb body comprised of a plurality of intersecting porous walls comprised of surfaces which define a plurality of channels extending from an inlet end to an outlet end, wherein the plurality of channels comprises inlet channels, which are sealed at locations spaced away from the inlet end, and outlet channels, which are sealed at locations spaced away from the outlet end; and
a porous inorganic network of refractory metal oxide nanoparticles disposed on, or in, or both on and in, at least some of the walls defining the inlet channels,
wherein the refractory metal oxide nanoparticles are bound by a high temperature binder comprising one or more inorganic components,
wherein a clean filtration efficiency of the filtration article is greater than or equal to 70% as measured by a clean filtration efficiency test; and
wherein the filtration article is moisture resistant such that the clean filtration efficiency of the article does not change by more than 5% after being exposed to; a water soak test, a water immersion test, a water nebulizer test, or combinations thereof.
2. The filtration article of claim 1 , wherein the high temperature binder is provided by a silicon-containing binder precursor.
3. The filtration article of the preceding claim , wherein the high temperature binder comprises at least one component which is stable at a temperature of greater than or equal to: 400° C., 500° C., 600° C., 700° C., 800° C., 900° C., 1000° C., 1100° ° C., 1200° C., or 1300° C.
4. The filtration article of claim 1 , wherein the high temperature binder is silicon-containing.
5. The filtration article of claim 2 , wherein the silicon-containing binder binds some of the refractory metal oxide nanoparticles to each other.
6. The filtration article of claim 2 , wherein the silicon-containing binder binds some of the refractory metal oxide nanoparticles to the porous walls of the honeycomb body.
7. The filtration article of claim 2 , wherein the silicon-containing binder binds the refractory metal oxide nanoparticles to each other and to the porous walls of the honeycomb body.
8. The filtration article of claim 2 , wherein the silicon-containing binder is one or more of the group consisting of silica, silicone resin, sodium silicate, colloidal silica, and combinations thereof.
9. The filtration article of claim 2 , wherein the silicon-containing binder precursor is a silicone resin.
10. The filtration article of claim 2 , wherein the silicon-containing binder precursor is a siloxane.
11. The filtration article of claim 2 , wherein the silicon-containing binder precursor is an alkoxysiloxane.
12. The filtration article of claim 2 , wherein the silicon-containing binder precursor is a silicate.
13. The filtration article of claim 2 , wherein the silicon-containing binder precursor is an alkaline silicate.
14. The filtration article of claim 2 , wherein the silicon-containing binder precursor is a sodium silicate.
15. The filtration article of claim 1 wherein the nanoparticles are present in the form of agglomerates.
16. The filtration article of claim 15 wherein the porous inorganic network comprises aggregates of the agglomerates.
17. The filtration article of claim 1 wherein the inorganic material of the porous inorganic network is present on the honeycomb filter body in a loading in a range of from 1 to 20 g/L.
18. The filtration article of claim 1 wherein the inorganic material of the porous inorganic network is present on the honeycomb filter body in a loading in a range of from 1 to 10 g/L.