Methods and materials for direct nox decomposition in lean exhaust gases

Patent metadata

Field	Value
Publication number	US-2017312742-A1
Application number	US-201615140087-A
Country	US
Kind code	A1
Filing date	Apr 27, 2016
Priority date	Apr 27, 2016
Publication date	Nov 2, 2017
Grant date	—

Abstract

A noble metal-free lanthanum transition metal perovskite catalyst material. The noble metal-free lanthanum transition metal perovskite catalyst material may include a two phase mixture of a lanthanum transition metal perovskite with an alkali or alkaline earth metal carbonate, a lanthanum transition metal perovskite doped with an alkali or alkaline earth metal, or a combination thereof. The lanthanum transition metal perovskite catalyst material provides direct decomposition of NOx into N 2 and O 2 without the presence of a noble metal and in the presence of excess O 2 .

First claim

What is claimed is:

1 . A noble metal-free (NMF) catalyst for the direct decomposition of NOx to N 2 and O 2 in a lean exhaust gas comprising:
a NMF catalyst material selected from at least one of:
a two phase mixture of a La transition metal perovskite with a chemical formula of La (1-y) L′ (y) M (1-x) M′ (x) O 3 (0.0≦y≦0.5; 0.0≦x≦0.5) and an alkali or alkaline earth metal carbonate with a chemical formula of A n CO 3 (n=integer);
wherein:
L′ is any combination of Sm, Eu, Gd, Tb, Dy, Lu, Er, Yb, Pr, Nd, Ho, Bi or Y, and M and M′ are any combination of Fe, Mn, Co, Cr, Ni, Sc, V, Nb, Ta, Sb, In or Ga, when a Goldschmidt tolerance factor for La (1-y) L′ (y) M (1-x) M′ (x) O 3 is between 0.7 and 1.0, inclusive; and
A n CO 3 is a carbonate of Na, K, Mg, Ca, Sr and Ba; and

a La transition metal perovskite with a chemical formula of La (1-y) L′ (y) M (1-x) M′ (x) O 3 (0.0≦y≦0.5; 0.0≦x≦0.5) doped with an alkali or alkaline earth metal of A′;
wherein:
L′ is any combination of Sm, Eu, Gd, Tb, Dy, Lu, Er, Yb, Pr, Nd, Ho, Bi or Y, and M and M′ are any combination of Fe, Co, and Ni when a Goldschmidt tolerance factor for La (1-y) L′ (y) M (1-x) M′ (x) O 3 is between 0.7 and 1.0, inclusive; and
A′ is at least one of Na, K, Mg and Ba.

2 . The NMF catalyst of claim 1 , wherein the NMF catalyst material is the two phase mixture of La transition metal perovskite and the alkali or alkaline earth metal carbonate.

3 . The NMF catalyst of claim 2 , wherein M is at least one of Fe and Co.

4 . The NMF catalyst of claim 3 , wherein A n CO 3 is at least one of CaCO 3 , SrCO 3 , K 2 CO 3 and BaCO 3 .

5 . The NMF catalyst of claim 4 , wherein A n CO 3 is BaCO 3 and a concentration of Ba in the NMF catalyst material is between 0.1 to 10 wt %, inclusive.

6 . The NMF catalyst of claim 5 , wherein M is Fe, y equals 0 and x equals 0.

7 . The NMF catalyst of claim 1 , wherein the NMF catalyst material is the La transition metal perovskite doped with the alkali or alkaline earth metal.

8 . The NMF catalyst of claim 7 , wherein M is at least one of Fe and Ni.

9 . The NMF catalyst of claim 8 , wherein M is Fe.

10 . The NMF catalyst of claim 9 , wherein A′ is Ba.

11 . The NMF catalyst of claim 10 , wherein a concentration of Ba in the NMF catalyst material is between 0.1 to 10 wt %, inclusive.

12 . A noble metal-free (NMF) catalyst for the direct decomposition of NOx to N 2 and O 2 in a lean exhaust gas comprising:
a two phase mixture of a La transition metal perovskite with a chemical formula of La (1-y) L′ (y) M (1-x) M′ (x) O 3 (0.0≦y≦0.5; 0.0≦x≦0.5) and an alkali or alkaline earth metal carbonate with a chemical formula of A n CO 3 (n=integer); wherein:
L′ is any combination of Sm, Eu, Gd, Tb, Dy, Lu, Er, Yb, Pr, Nd, Ho, Bi or Y, and M and M′ are any combination of Fe, Mn, Co, Cr, Ni, Sc, V, Nb, Ta, Sb, In or Ga when a Goldschmidt tolerance factor for La (1-y) L′ (y) M (1-x) M′ (x) O 3 is between 0.7 and 1.0, inclusive; and
A n CO 3 is a carbonate of Na, K, Mg, Ca, Sr and Ba.

13 . The NMF catalyst of claim 12 , wherein M is at least one of Fe and Co, and A n CO 3 is at least one of CaCO 3 , SrCO 3 , K 2 CO 3 and BaCO 3 .

14 . The NMF catalyst of claim 13 , wherein A n CO 3 is BaCO 3 .

15 . The NMF catalyst of claim 14 , wherein a concentration of Ba in the two phase mixture of the La transition metal perovskite and the alkali or alkali metal carbonate is between 0.1 to 10 wt %, inclusive.

16 . The NMF catalyst of claim 14 , wherein M is Fe, y equals 0 and x equals 0.

17 . A method for the direct decomposition of NOx to N 2 and O 2 in a lean exhaust gas comprising:
flowing an exhaust gas generated by an internal combustion engine through a noble metal-free (NMF) catalyst, the exhaust gas containing NOx and excess O 2 , the NMF catalyst containing at least one of:
a two phase mixture of La transition metal perovskite with a chemical formula of La (1-y) L′ (y) M (1-x) M′ (x) O 3 (0.0≦y≦0.5; 0.0≦x≦0.5) and an alkali or alkaline earth metal carbonate with a chemical formula of A n CO 3 (n=integer);
wherein:
L′ is any combination of Sm, Eu, Gd, Tb, Dy, Lu, Er, Yb, Pr, Nd, Ho, Bi or Y, and M and M′ are any combination of Fe, Mn, Co, Cr, Ni, Sc, V, Nb, Ta, Sb, In or Ga, when a Goldschmidt tolerance factor for the La (1-y) L′ (y) M (1-x) M′ (x) O 3 is between 0.7 and 1.0, inclusive; and
A n CO 3 is a carbonate of Na, K, Mg, Ca, Sr and Ba;

a La transition metal perovskite with a chemical formula of La (1-y) L′ (y) M (1-x) M′ (x) O 3 (0.0≦y≦0.5; 0.0≦x≦0.5) doped with an alkali or alkaline earth metal of A′;
wherein:
M and M′ is at least one of Mn, Fe, Co and Ni; and
A′ is at least one of Na, K, Mg and Ba; and

directly decomposing the NOx into N 2 and O 2 using the NMF catalyst.

18 . The method of claim 17 , wherein the NMF catalyst is the two phase mixture of La transition metal perovskite and alkali or alkaline earth metal carbonate, wherein M is at least one of Fe and Co, and A n CO 3 is at least one of CaCO 3 , SrCO 3 , K 2 CO 3 and BaCO 3 .

19 . The method of claim 18 , wherein A n CO 3 is BaCO 3 .

20 . The method of claim 19 , wherein a concentration of Ba in the two phase mixture of La (1-y) L′ (y) M (1-x) M′ (x) O 3 and BaCO 3 is between 0.1 to 10 wt %, inclusive.

Assignees

• Toyota Motor Eng & Mfg North America Inc

Inventors

• Peck Torin C
• Gunugunuri Krishna Reddy
• Ling Chen
• Jia Hongfei

Classifications

• B01J23/83

  with rare earths or actinides · CPC title

• B01J23/002

  Mixed oxides other than spinels, e.g. perovskite · CPC title

• B01J35/0006

  Operations & Transport · mapped topic

• B01D2255/402

  Perovskites · CPC title

• B01D53/9413

  Processes characterised by a specific catalyst · CPC title