SCRF COATINGS
The present disclosure relates to a coated filter for filtering particulate matter from exhaust gases. The filter has a porous catalyst composition coating, said catalyst composition comprises a zeolite, copper and manganese. The present disclosure also relates to a method forming the coated filter as described herein and an exhaust system with a coated filter as described herein.
1 . A filter with a catalyst composition coating, said catalyst composition comprises:
a) a zeolite,
b) copper, and
c) manganese,
wherein the catalyst composition is porous.
2 . The filter of claim 1 , wherein said zeolite is selected from CHA, AEI, FER, MFI, STW, BEA, FAU, AI, MAZ, MOR and OFF, preferably CHA or AEI, more preferably CHA.
3 . The filter of claim 1 , wherein said zeolite has a SAR of between 10 and 30.
4 . The filter of claim 1 , wherein the copper is in an amount of from about 0.5 to about 5 wt % based the weight of the zeolite.
5 . The filter of claim 1 , wherein manganese is in an amount of from about 0.1 to about 3 wt % based on the weight of the zeolite.
6 . The filter of claim 1 , wherein the catalyst composition is calcined.
7 . The filter of claim 6 , wherein the wherein the mean pore size of the calcined catalyst composition is in the range of 0.1 μm to 10 μm.
8 . The filter of claim 1 , wherein the catalyst composition further comprises:
I. one or more binders, preferably one or more binders selected from alumina, silica, silica-alumina, naturally occurring clays, TiO 2 , ZrO 2 , or SnO 2 ,
II. one or more rheology modifiers, preferably rheology modifiers such as Natrosol, TEAOH Dispex or ammonia, and/or
III. one or more pore formers, preferably pore formers selected from cellulose pore formers, polyethylene, starch, graphite, polypropylene, polyaramides, polytetrafluoroethylene, polystyrene, cellulose fibres and polymethacrylmethacrylate.
9 . The filter of claim 1 , wherein the filter is coated with at least two catalyst compositions, a first catalyst composition and a second catalyst composition, wherein:
the first catalyst composition comprises a zeolite, copper, manganese, a binder, and a rheology modifier,
the second catalyst composition is as defined in claim 1 , and additionally comprises a binder, a rheology modifier, and a pore former.
10 . The filter of claim 9 , wherein the first catalyst composition is coated along 50-100% of the length of the substrate.
11 . The filter of claim 9 , wherein the first catalyst composition is an in-wall coating.
12 . The filter of claim 1 , wherein the first catalyst composition has a viscosity of between 2-20 cPs.
13 . The filter of claim 1 , wherein the second catalyst composition is coated along 50-100% of the length of the substrate.
14 . The filter of claim 9 , wherein the second catalyst composition is an on-wall coating.
15 . The filter of claim 9 , wherein the second catalyst composition has a viscosity of between 10-1800 cPs.
16 . The filter of claim 9 , wherein the weight ratio of the first catalyst composition:second catalyst composition is 1:1 to 5:1.
17 . A method of forming a coated filter, said method comprising:
i) incorporating copper and manganese into the zeolite to form a catalyst composition,
ii) forming a first washcoat comprising the catalyst composition of step i), one or more binders and one or more rheology modifiers,
iii) applying the first washcoat to the filter,
iv) optionally drying the filter,
v) forming a second washcoat comprising the catalyst composition of step i), one or more binders, one or more rheology modifiers and one or more pore formers,
vi) applying the second washcoat to the filter coated with the first washcoat from step iii) or step iv)
vii) drying and calcining the article to form a coated filter.
18 . The filter of claim 8 , wherein the binder is one or more aluminas, the rheology modifier is selected from Natrosol and TEAOH, and pore former is selected from Arbocel and Vivapur.
19 . A filter as defined in claim 1 , for the treatment of an exhaust gas.
20 . A vehicular exhaust system comprising the filter as defined in claim 1 .