Catalysts and methods for denitrization

Claim 2

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) at least one metal oxide selected from TiO₂, Al₂O₃, ZrO₂ and SiO₂; (B) at least one oxide of rare earth metal; and (C) at least one metal or oxide of metal selected from Pd, Ru, Rh, Ag and Pt in an atomic ratio of A/B/C of 99-70/1-20/0.01-10.

Claim 3

The catalyst as claimed in claim 2 wherein the oxide of rare earth metal is Tb₄O₇, Nd₂O₃, Pr₆O₁₁ or CeO₂.

Claim 4

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) TiO₂; (B) at least one metal oxide selected from of Al₂O₃, SiO₂ and ZrO₂; and (C) at least one oxide of metal selected from V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo and W in an atomic ratio of A/B/C of 99-50/5-50/0.01-20.

Claim 5

The catalyst as claimed in claim 4 wherein the atomic ratio of A/B/C is 90-75/10-25/0.5-10.

Claim 6

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) TiO₂; (B) at least one metal oxide selected from Al₂O₃, SiO₂ and ZrO₂; and (C) at least one oxide of metal or metal selected from Ru, Rh, Pd, Ag or Pt, in an atomic ratio of A/B/C of 90-50/5-50/0.01-10.

Claim 7

The catalyst as claimed in claim 6 wherein the atomic ratio of A/B/C is 90-75/10-25/0.1-5.

Claim 8

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) substituted zeolite having the general formula M¹ A M² B [(AlO₂) X (SiO₂) Y ]·Z H₂O in which M¹ represents alkali metal, alkaline earth metal or hydrogen ion; M² is at least one metal ion selected from Ti⁴⁺, Zr⁴⁺ and Sn⁴⁺; n₁A + n₂B = X wherein n₁ is the valency of ion M¹ and n₂ is the valency of ion M²; and Y/X ≧ 5; the M² ion being contained in an amount of 0,1-20 % by weight based on the zeolite; and (B) at least one metal or oxide of metal selected from Pd and Pt supported on the substituted zeolite in an amount of 0.1-10 % by weight based on the zeolite.

Claim 9

The catalyst as claimed in claim 8 which further comprises at least one oxide selected from TiO₂, ZrO₂ and SnO₂ supported on the zeolite in an amount of 0,1-20 % by weight in terms of metal based on the zeolite.

Claim 10

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) zeolite having the general formula M¹ A [(AlO₂) X (SiO₂) Y ]·Z H₂O in which M¹ represents alkali metal, alkaline earth metal or hydrogen ion; n₁A = X wherein n₁ is the valency of ion M¹; and Y/X ≧ 5; (C) at least one oxide selected from TiO₂, ZrO₂ and SnO₂ supported on the zeolite in an amount of 0.1-20 % by weight in terms of metal based on the zeolite; and (B) at least one metal or oxide of metal selected from Pd and Pt supported on the substituted zeolite in an amount of 0.1-10 % by weight based on the zeolite.

Claim 11

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) substituted zeolite having the general formula M¹ A M² B [(AlO₂) X (SiO₂) Y ]·Z H₂O in which M¹ represents alkali metal, alkaline earth metal or hydrogen ion; M² is at least one metal ion selected from Ti⁴⁺, Zr⁴⁺ and Sn⁴⁺; n₁A + n₂B = X wherein n₁ is the valency of ion M¹ and n₂ is the valency of ion M²; and Y/X ≧ 5; the M² ion being contained in an amount of 0,1-20 % by weight based on the zeolite; (B) at least one metal or oxide of metal selected from Ru, Rh and Ag supported on the substituted zeolite; and optionally (D) at least one metal or oxide of metal selected from Pd and Pt supported on the substituted zeolite; the metal or oxide (B) and the metal or oxide (D) being contained in a total amount of 0.1-10 % by weight based on the zeolite.

Claim 12

The catalyst as claimed in claim 11 which further comprises at least one oxide selected from TiO₂, ZrO₂ and SnO₂ supported on the zeolite in an amount of 0.1-20 % by weight in terms of metal based on the zeolite.

Claim 13

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) zeolite having the general formula M¹ A [(AlO₂) X (SiO₂) Y ]·Z H₂O in which M¹ represents alkali metal, alkaline earth metal or hydrogen ion; n₁A = X wherein n₁ is the valency of ion M¹; and Y/X ≧ 5; (C) at least one oxide selected from TiO₂, ZrO₂ and SnO₂ supported on the zeolite in an amount of 0.1-20 % by weight in terms of metal based on the zeolite; (B) at least one metal or oxide of metal selected from Ru, Rh and Ag supported on the substituted zeolite; and optionally (D) at least one metal or oxide of metal selected from of Pd and Pt supported on the substituted zeolite; the metal or oxide (B) and the metal or oxide (D) being contained in a total amount of 0.1-10 % by weight based on the zeolite.

Claim 14

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) substituted zeolite having the general formula M¹ A M² B [(AlO₂) X (SiO₂) Y ]·Z H₂O in which M¹ represents alkali metal, alkaline earth metal or hydrogen ion; M² is at least one metal ion selected from Ti⁴⁺, Zr⁴⁺ and Sn⁴⁺; n₁A + n₂B = X wherein n₁ is the valency of ion M¹ and n₂ is the valency of ion M²; and Y/X ≧ 5; the M² ion being contained in an amount of 0.1-20 % by weight based on the zeolite; and (B) at least one oxide of metal selected from V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo and W in an amount of 0.1-20 % by weight based on the zeolite.

Claim 15

The catalyst as claimed in claim 14 which further comprises at least one oxide selected from TiO₂, ZrO₂ and SnO₂ supported on the zeolite in an amount of 0.1-20 % by weight in terms of metal based on the zeolite; and

Claim 16

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises: (A) zeolite having the general formula M¹ A [(AlO₂) X (SiO₂) Y ]·Z H₂O in which M¹ represents alkali metal, alkaline earth metal or hydrogen ion; n₁A = X wherein n₁ is the valency of ion M¹; and Y/X ≧ 5; (C) at least one oxide selected from TiO₂, ZrO₂ and SnO₂ supported on the zeolite in an amount of 0.1-20 % by weight in terms of metal based on the zeolite; and (B) at least one oxide of metal selected from V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo and W in an amount of 0.1-10 % by weight based on the zeolite.

Claim 17

A catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent, which comprises perovskite structure complex compound having the general formula La X Sr (1 - X) B¹ Y B² (1 - Y) O₃ wherein B¹ represents at least one metal selected from Mn and Co; B² represents at least one metal selected from Co, Fe, Ni, Cu and Cr; and 0 ≦ X ≦ 1 and 0 ≦ Y ≦ 1.

Claim 18

The catalyst as claimed in claim 1 which further comprises at least one metal or oxide of metal selected from Pt, Rh, Pd, Ru and Ag supported on the perovskite structure complex compound in an amount of 0.1-10 % by weight based on the perovskite structure complex compound.

Claim 19

The catalyst as claimed in claim 1 which further comprises heat resistant material selected from alumina, silica, titanium dioxide and zirconium oxide which supports the catalyst thereon in an amount of not less than 1 % by weight based on the carrier material.