METHOD OF FORMING AN INORGANIC OXIDE COATING ON A MONOLITH ARTICLE
An uncalcined monolith article comprises a dry particulate composition comprising inorganic particles and a silicone resin. The uncalcined monolith article can be prepared by spraying, as a dry particulate aerosol, inorganic particles and a silicone resin on a monolith article to form a coating layer.
1 . An uncalcined porous monolith article for use in forming a monolith article for the treatment of an exhaust gas, the uncalcined porous monolith article comprising a plurality of channels and comprising a dry particulate composition comprising inorganic particles and a silicone resin, the dry particulate composition being located within the channels and/or pores of said uncalcined porous monolith.
2 . The uncalcined porous monolith article according to claim 1 , wherein the uncalcined porous monolith article is a monolith filter.
3 . The uncalcined porous monolith article according to claim 1 , wherein the uncalcined porous monolith article is a catalytic wall-flow filter.
4 . The uncalcined porous monolith article according to claim 3 , wherein the catalytic wall-flow filter comprises a three-way catalyst.
5 . The uncalcined porous monolith article according to claim 3 , wherein the catalytic wall-flow filter comprises a selective reduction catalyst.
6 . The uncalcined porous monolith article according to claim 3 , wherein the catalytic wall-flow filter comprises an oxidation catalyst.
7 . The uncalcined porous monolith article according to claim 1 , wherein the silicone resin has a molecular weight of greater than 1,000 and less than 200,000.
8 . The uncalcined porous monolith article according to claim 1 , wherein the silicone resin has a glass transition temperature (Tg) of greater 35° C. and less than 80° C.
9 . The uncalcined porous monolith article according to claim 1 , wherein the silicone resin has the formula [R x SiX y O z ] n , wherein R is an alkyl or aryl, X is a functional group bonded to silicon, and wherein z is more than 1 and less than 2.
10 . The uncalcined porous monolith article according to claim 9 , wherein y is less than 1 and wherein y is less than x.
11 . The uncalcined porous monolith article according to claim 9 , wherein the silicone resin has a degree of crosslinking of greater than 65% and less than 80%.
12 . The uncalcined porous monolith article according to claim 9 , wherein R is one or more of C 1 -C 6 alkyls and phenyl.
13 . The uncalcined porous monolith article according to claim 9 , wherein X is one or more of H, OH, Cl and C 1 -C 6 alkoxy.
14 . The uncalcined porous monolith article according to claim 1 , wherein the silicon dioxide content of the silicone resin is greater 80 wt %.
15 . The uncalcined porous monolith article according to claim 1 , wherein the inorganic particles are selected from the consisting of zeolites, refractory oxides, and their mixtures.
16 . The uncalcined porous monolith article according to claim 1 , wherein the inorganic particles are refractory oxide particles comprising calcium aluminate, fumed alumina, fumed silica, fumed titania, fumed zirconia, fumed ceria, alumina aerogel, silica aerogel, titania aerogel, zirconia aerogel, ceria aerogel or a mixture thereof.
17 . The uncalcined porous monolith article according to claim 1 , wherein the inorganic particles have a d 50 by volume of greater than 0.2 μm and less than 50 μm
18 . The uncalcined porous monolith article according to claim 1 , wherein calcining comprises heating to a temperature of at least 400° C. and at most 530° C.
19 . The uncalcined porous monolith article according to claim 1 , wherein the monolith article comprises one or more platinum group metals.
20 . The uncalcined porous monolith article according to claim 1 , wherein a mass loading of the dry particulate composition on the uncalcined porous monolith article is less than 30 g/L.