Catalyst and method for catalytic reduction of nitrogen oxides
The invention provides a catalyst for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, which catalyst comprises: (A) a catalyst component A comprising (c) ceria or (d) praseodymium oxide or (e) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; (B) a catalyst component B comprising (d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and (e) a carrier; and (C) a catalyst component C comprising (f) a solid acid, and (g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese.
1. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst, which catalyst comprises:
(A) a catalyst component A which comprises
(c) ceria or
(d) praseodymium oxide or
(e) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum;
(B) a catalyst component B which comprises
(d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and
(e) a carrier; and
(C) a catalyst component C which comprises
(f) a solid acid, and
(g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese.
2. A method as claimed in claim 1 wherein the catalyst component A supports thereon at least one noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof.
3. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst, which catalyst comprises:
an outer catalyst layer comprising a catalyst component A and a catalyst component C, as an outer catalyst component, wherein the catalyst component A comprises
(A) (a) ceria or
(b) praseodymium oxide or
(c) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and
the catalyst component C comprises
(C) (f) a solid acid, and
(g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese; and
an inner catalyst layer comprising a catalyst component B, as an inner catalyst component, wherein the catalyst component B comprises
(B) (d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and
(e) a carrier.
4. A method as claimed in claim 3 wherein the catalyst component A supports thereon at least one noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof.
5. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst, which catalyst comprises:
an outer catalyst layer comprising a catalyst component A and a catalyst component C, as an outer catalyst component, wherein the catalyst component A comprises
(A) (a) ceria or
(b) praseodymium oxide or
(c) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and
the catalyst component C comprises
(C) (f) a solid acid, and
(g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese; and
an inner catalyst layer comprising a catalyst component A and a catalyst component C, as an inner catalyst component, wherein the catalyst component A comprises
(A) (a) ceria or
(b) praseodymium oxide or
(c) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and
the catalyst component B comprises
(B) (d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and
(e) a carrier.
6. A method as claimed in claim 5 wherein at least one of the catalyst component A in the outer catalyst component and the catalyst component A in the inner catalyst component supports thereon at least one noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof.
7. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst structure, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 1 .
8. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst structure, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 3 .
9. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst structure, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 2 .
10. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst structure, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 4 .
11. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst structure, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 5 .
12. A method for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact with a catalyst structure, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 6 .
13. A catalyst for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, which catalyst comprises:
(A) a catalyst component A comprising
(c) ceria or
(d) praseodymium oxide or
(e) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum;
(B) a catalyst component B comprising
(d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and
(e) a carrier; and
(C) a catalyst component C comprising
(f) a solid acid, and
(g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese.
14. A catalyst as claimed in claim 13 wherein the catalyst component A supports thereon at least one noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof.
15. A catalyst for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, which catalyst comprises:
an outer catalyst layer comprising a catalyst component A and a catalyst component C, as an outer catalyst component, wherein the catalyst component A comprises
(A) (a) ceria or
(b) praseodymium oxide or
(c) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and
the catalyst component C comprises
(C) (f) a solid acid, and
(g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese; and
an inner catalyst layer comprising a catalyst component B, as an inner catalyst component, wherein the catalyst component B comprises
(B) (d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and
(e) a carrier.
16. A catalyst as claimed in claim 15 wherein the catalyst component A supports thereon at least one noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof.
17. A catalyst for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, which catalyst comprises:
an outer catalyst layer comprising a catalyst component A and a catalyst component C, as an outer catalyst component, wherein the catalyst component A comprises
(A) (a) ceria or
(b) praseodymium oxide or
(c) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and
the catalyst component C comprises
(C) (f) a solid acid, and
(g) a solid acid supporting an oxide of at least one element selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel and manganese; and
an inner catalyst layer comprising a catalyst component A and a catalyst component C, as an inner catalyst component, wherein the catalyst component A comprises
(A) (a) ceria or
(b) praseodymium oxide or
(c) an oxide and/or a composite oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium and lanthanum; and
the catalyst component B comprises
(B) (d) a noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof and
(e) a carrier.
18. A catalyst as claimed in claim 17 wherein at least one of the catalyst component A in the outer catalyst component and the catalyst component A in the inner catalyst component supports thereon at least one noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium and oxides thereof.
19. A catalyst structure for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 13 .
20. A catalyst structure for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 15 .
21. A catalyst structure for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 14 .
22. A catalyst structure for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 16 .
23. A catalyst structure for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 17 .
24. A catalyst structure for catalytic reduction of nitrogen oxides contained in exhaust gases wherein fuel is supplied and subjected to combustion under periodic rich/lean conditions and the resulting exhaust gases are brought into contact therewith, in which the catalyst structure comprises an inactive substrate and the catalyst as claimed in claim 18 .