Coated filters
The present disclosure relates to a powder coated article for filtering particulate matter from exhaust gases. The powder coated article comprises a coated monolith article, and a powder coating on the coated monolith article. The coated monolith article is a monolith article coated with an on-wall washcoat, and the powder coating comprises an inorganic particle and a silicone resin in a ratio of between 50:1 to 1:9. The present disclosure also relates to a method forming said powder coated article.
1 . A powder coated article, said powder coated article comprising:
a) a coated monolith article, and
b) a powder coating on the coated monolith article,
wherein said coated monolith article is a monolith article coated with an on-wall washcoat, and said powder coating comprising an inorganic particle and a silicone resin in a ratio, by weight, of between 50:1 to 1:9;
wherein the coated monolith article is a coated catalytic wall-flow filter having a plurality of inlet channels and a plurality of outlet channels;
wherein at least 50% of washcoat in the inlet channels of the coated monolith article is present on-wall;
wherein the silicone resin has a melting point of less than 150° C. and a d 90 (by volume) of between 0.1 μm and 100 μm.
2 . The powder coated article according to claim 1 , wherein said inorganic particle is a small pore zeolite.
3 . The powder coated article according to claim 1 , wherein said inorganic particle is a CHA zeolite.
4 . The powder coated article according to claim 1 , wherein the ratio, by weight, of the inorganic particle to silicone resin is between 4:1 and 1:1.
5 . The powder coated article according to claim 1 , wherein the inorganic particle has a d 90 (by volume) of between 0.1 μm and 100 μm.
6 . The powder coated article according to claim 1 , wherein the mass loading of the powder coating is between 0.1 g/L and 50 g/L.
7 . A method of forming a powder coated article according to claim 1 , said method comprising:
i) providing a coated monolith article,
ii) spraying onto the coated monolith article, as a dry particulate aerosol, inorganic particles and a silicone resin to form a powder coating layer,
wherein said inorganic particles and silicone resin are in a ratio of between 50:1 to 1:9.
8 . The method according to claim 7 , wherein said spraying step is performed under a constant flow of gas.
9 . The method according to claim 7 , wherein said method comprises a further step of:
iii) calcining the powder coating layer to provide a calcined powder coated article.
10 . The method according to claim 9 , wherein said calcining step comprises heating to a temperature of at least 200° C. and at most 550° C.