Exhaust gas treatment catalyst and exhaust gas treatment method
The present invention provides an exhaust gas treatment catalyst characterized by containing a compound oxide expressed by the following general formula (1), AMxOy (1) (wherein A represents an alkali metal or alkaline earth metal, M represents Cr, Mn, Fe, Co or Ni, O represents oxygen, and 0<x≦4 and 0<y≦8) and an exhaust gas treatment method using the said catalyst. According to the present invention, there can be provided an exhaust gas treatment compound oxide that can effectively remove particulates and NOx contained in exhaust gas with a high oxygen concentration that is discharged from a diesel engine etc., and also has excellent resistance to sulfur poisoning.
1. An exhaust gas treatment catalyst characterized by containing a compound oxide expressed by the following general formula (1):
AMxOy (1)
(wherein A represents an alkali metal or alkaline earth metal, M represents Cr, Mn, Fe, Co or Ni, O represents oxygen, and 0<x≦4 and 0<y≦8); and
further containing a perovskite compound oxide expressed by the following general formula (2) in addition to said compound oxide of general formula (1):
Ln 1-α A α MO3 (2)
(wherein Ln represents a lanthanide group element, A represents an alkali metal, M represents Cr, Mn, Fe, Co or Ni, O represents oxygen, and 0<α≦0.5),
wherein a noble metal is contained in some of said compound oxide of general formula (1).
2. The exhaust gas treatment catalyst according to claim 1 , characterized in that in said general formula (1), M is Co or Fe.
3. The exhaust gas treatment catalyst according to claim 1 , characterized in that in said general formula (1), A is at least one kind selected from a group consisting of Li, Na, K, Cs, Rb and Ba.
4. The exhaust gas treatment catalyst according to claim 1 , characterized in that in said general formula (2), Ln is La.
5. The exhaust gas treatment catalyst according to claim 1 , characterized in that said noble metal is at least one kind selected from a group consisting of Au, Ag, Pt, Pd, Ir, Rh and Ru.
6. The exhaust gas treatment catalyst according to claim 1 , characterized by further containing a carbonate of an alkali metal or alkaline earth metal.
7. The exhaust gas treatment catalyst according to claim 6 , characterized in that said carbonate is at least one kind selected from a group consisting of Li2CO3, Na2CO3, K2CO3, Cs2CO3, Rb2CO3 and Ba2CO3.
8. The exhaust gas treatment catalyst according to any one of claims 1 - 3 , 4 , 5 , 6 or 7 , characterized in that said catalyst is carried on a carrier, and said carrier is at least one kind selected from a group consisting of alumina, zirconia, silica alumina, silica, and zeolite.
9. An exhaust gas treatment method for treating exhaust gas by using the exhaust gas treatment catalyst described in any one of claims 1 - 3 , 4 , 5 , 6 , or 7 , characterized in that by fine powder of said exhaust gas treatment catalyst carried on a filter-form carrier, particulates in exhaust gas are removed by burning, and at the same time, nitrogen oxides are removed.