Manganese oxide-lanthanum manganate-pgm composites for twc applications

Patent metadata

Field	Value
Publication number	US-2020316568-A1
Application number	US-202016837085-A
Country	US
Kind code	A1
Filing date	Apr 1, 2020
Priority date	Apr 6, 2019
Publication date	Oct 8, 2020
Grant date	—

Abstract

The present disclosure is directed to compositions for use in oxygen capture applications, for example in three-way catalysts (TWC) systems. In some embodiments, the compositions comprise composites of aggregated and/or fused primary particles, the aggregated and/or fused primary particles collectively having the formulae [MnO x ] y :[La z MnO 3 ] 1−y ; wherein
x is in a range from about 1 to 2.5; y is in a range from about 1 to about 30 wt %, or from about 1 to about 20 wt % or from about 2-10 wt % or from about 2 to about 5 wt %; and z is about 0.7 to about 1.1; and the La z MnO 3 is a crystalline perovskite phase; the aggregated and/or fused primary particles of the composite having a mean surface area in a range of from about 25 to about 60 m 2 /g, preferably from about 27 to about 45 m 2 /g. In preferred embodiments, these compositions further comprise low levels of at least one platinum group metal (PGM), preferably Pd.

First claim

1 . A composition comprising a composite of aggregated and/or fused primary particles collectively having a formula of [MnO x ] y :[LaMnO 3 ] 1−y ;
wherein
x is from about 1 to about 2.5;
y is from about 1 to about 30 wt %;
z is about 0.7 to about 1.1; and
the La z MnO 3 is a crystalline perovskite phase;

and wherein the composite of aggregated and/or fused primary particles has a mean surface area of about 25 to about 60 m 2 /g.

2 . The composition of claim 1 , wherein the MnO x is amorphous.

3 . The composition of claim 1 , wherein the MnO x is crystalline.

4 . The composition of claim 1 , wherein the primary particles independently comprise MnO x and La z MnO 3 .

5 . The composition of claim 4 , wherein the primary particles of MnO x are present in a size range of from about 10 nm to about 60 nm, preferably from about 12 nm to about 25 nm, or from about 14 nm to about 50 nm and/or the primary particles of La z MnO 3 are present in a size of from about 10 nm to about 50 nm, preferably from about 12 nm to about 25 nm.

6 . The composition of claim 1 , wherein the MnO x is predominantly Mn 3 O 4 , Mn 5 O 8 , or a combination thereof.

7 . The composition of claim 1 , wherein z is a value in a range of from about 0.7 to about 1.1, from about 0.8 to about 1.1, from about 0.8 to about 0.99, or from about 0.8 to about 0.95.

8 . The composition of claim 1 , further comprising La 2 O 2 CO 3 .

9 . The composition of claim 1 , further comprising a platinum group metal (PGM) in an amount of about 0.01 wt % to about 0.5 wt %, relative to the weight of the entire composition, preferably where the PGM is Pd, and/or the PGM is situated predominantly on the surface of the primary particles.

10 . The composition of claim 1 , prepared by:
(a) precipitating a lanthanum-manganese hydroxide precursor from an aqueous solution comprising lanthanum and manganese, the lanthanum and manganese each independently being a salt comprising acetylacetonate, carboxylate, carbonate, halide, nitrate, and/or oxalate, using an alkali metal hydroxide, thereby providing an aqueous suspension having a pH in a range of from about 9 to about 13; then (b) calcining the lanthanum-manganese hydroxide at a temperature in a range of from about 600° C. to about 1100° C.; and then optionally (c) depositing the PGM onto the composition particles.

11 . An automotive catalytic converter comprising a washcoat, the washcoat comprising a composition of claim 1 .

12 . An oxygen storage device comprising a three-way catalyst comprising the composition of claim 1 .

13 . A three-way catalyst comprising a composition of claim 1 , wherein the composition independently exhibits efficiencies for the conversion of hydrocarbon (HC), CO, and NO x of at least 85% relative to a comparable Ce 0.5 Zr 0.5 O 2 -based composition when operated at a temperature in a range of from about 350° C. to about 550° C.

14 . A method of treating an exhaust gas from an internal combustion engine, the method comprising contacting the exhaust gas with a three-way catalyst of claim 13 .

Assignees

• Johnson Matthey Plc

Inventors

• Fisher Janet
• Pascui Andrea Eva

Classifications

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J35/45

  Nanoparticles · CPC title

• B01J35/733

  Perovskite-type · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title