Catalyst combining platinum group metal with copper-alumina spinel

Patent metadata

Field	Value
Publication number	US-2020001280-A1
Application number	US-201916561725-A
Country	US
Kind code	A1
Filing date	Sep 5, 2019
Priority date	Mar 6, 2017
Publication date	Jan 2, 2020
Grant date	—

Abstract

An oxidation catalyst composition is provided, the composition including at least one platinum group metal impregnated onto a porous alumina material, wherein the porous alumina material comprises a copper-alumina spinel phase. At least a portion of the copper-alumina spinel phase can be proximal to, or in direct contact with, at least one platinum group metal crystallite, such as a crystallite having a size of about 1 nm or greater. The close proximity of the copper-alumina spinel phase to the platinum group metal crystallite is believed to provide synergistic enhancement of carbon monoxide oxidation. Methods of making and using the catalyst composition are also provided, as well as emission treatment systems comprising a catalyst article coated with the catalyst composition.

First claim

1 . An oxidation catalyst composition, the composition comprising at least one platinum group metal impregnated onto a porous alumina material, wherein the porous alumina material comprises a copper-alumina spinel phase.

2 . The oxidation catalyst composition of claim 1 , wherein at least one portion of the copper-alumina spinel phase is proximal to, or in direct contact with, at least one platinum group metal crystallite.

3 . The oxidation catalyst composition of claim 2 , wherein at least one portion of the copper-alumina spinel phase is proximal to, or in direct contact with, at least one platinum group metal crystallite having a crystallite size of about 1 nm or greater.

4 . The oxidation catalyst composition of claim 3 , wherein at least one portion of the copper-alumina spinel phase is proximal to, or in direct contact with, at least one platinum group metal crystallite having a crystallite size of about 50 nm or greater.

5 . The oxidation catalyst composition of claim 2 , wherein the at least one portion of the copper-alumina spinel phase is within about 50 nm of the at least one platinum group metal crystallite.

6 . The oxidation catalyst composition of claim 1 , wherein the porous alumina material comprises copper, calculated as copper oxide, in an amount of about 1 to about 40% by weight, based on the total weight of the porous alumina material.

7 . The oxidation catalyst composition of claim 1 , wherein the platinum group metal is platinum, palladium, or a combination thereof.

8 . The oxidation catalyst composition of claim 1 , wherein the concentration of at least one platinum group metal is about 0.1 wt. % to about 10 wt. % relative to the weight of the porous alumina material.

9 . The oxidation catalyst composition of claim 1 , wherein the T 50 for CO oxidation of the oxidation catalyst composition is lower than the T 50 for CO oxidation of a comparable oxidation catalyst composition containing the same amount of platinum group metal impregnated on alumina devoid of copper.

10 . The oxidation catalyst composition of claim 1 , wherein the oxidation catalyst composition is characterized by X-ray powder diffraction interplanar spacing peaks comprising a peak between about 30 and about 35 degrees 2θ and a peak between about 35 degrees and about 40 degrees 2θ.

11 . An oxidation catalyst composition, the composition comprising at least one platinum group metal impregnated onto a porous alumina material comprising predominantly alumina mixed with copper oxide, wherein the catalyst composition produces a copper-alumina spinel phase upon thermal aging for 20 hours at a temperature of 800° C. in air with 10% by volume steam.

12 . The oxidation catalyst composition of claim 11 , wherein the T 50 for CO oxidation of the oxidation catalyst composition is lower after said thermal aging.

13 . A catalyst article, comprising a catalyst substrate having a plurality of channels adapted for gas flow, the catalyst substrate having a catalyst coating disposed thereon, wherein the catalyst coating comprises the oxidation catalyst composition of claim 1 .

14 . The catalyst article of claim 13 , wherein the catalyst substrate is a catalyzed soot filter.

15 . The catalyst article of claim 13 , wherein the oxidation catalyst composition is disposed in a first layer on the catalyst substrate, and wherein the catalyst article further comprises a second layer comprising at least one platinum group metal impregnated on a refractory metal oxide support optionally in combination with a zeolite.

16 . The catalyst article of claim 13 , wherein the catalyst article comprises an inlet zone proximal to an inlet face of the catalyst article and an outlet zone proximal to an outlet face of the catalyst article, wherein the oxidation catalyst composition is disposed only in either the inlet zone or the outlet zone.

17 . A method of treating an exhaust stream, comprising passing the exhaust stream through a catalyst article according to claim 13 such that carbon monoxide and hydrocarbon gases within the exhaust stream are oxidized within the catalyst article.

18 . The method of claim 17 , wherein the exhaust stream is produced by a lean burn engine.

19 . An emission treatment system for treatment of an exhaust gas stream, the emission treatment system comprising:
a lean burn engine producing an exhaust gas stream; and a catalyst article according to claim 13 positioned in fluid communication with the exhaust gas stream and adapted for oxidation of carbon monoxide and hydrocarbon gases within the exhaust stream to form a treated exhaust gas stream.

20 . A method of preparing an oxidation catalyst composition comprising a copper-alumina spinel phase, comprising:
receiving a porous alumina material comprising predominantly alumina mixed with copper oxide; impregnating the porous alumina material with one or more water soluble salts of a platinum group metal; drying and calcining the porous alumina material after said impregnating step to form a catalyst composition; and thermally treating the porous alumina material to form a copper-alumina spinel phase either before or after said impregnating step.

21 . The method of claim 20 , further comprising forming a washcoat slurry of the catalyst composition; coating the washcoat slurry onto a catalyst substrate comprising a plurality of channels adapted for gas flow to form a catalyst article, and calcining the catalyst article, wherein said thermally treating step comprises thermally treating the resulting catalyst article to form the copper-alumina spinel phase.

22 . The method of claim 20 , wherein the concentration of at least one platinum group metal is about 0.1 wt. % to about 10 wt. % relative to the weight of the porous alumina material upon which the platinum group metal is impregnated.

23 . The method of claim 20 , wherein the porous alumina material comprises copper oxide in an amount of about 1 to about 40% by weight, based on the total weight of the porous alumina material.

24 . The method of claim 20 , wherein the platinum group metal comprises platinum, palladium, or a combination thereof.

25 . The method of claim 20 , wherein said thermally treating step causes sintering of platinum group metal crystallites such that at least one portion of the copper-alumina spinel phase is proximal to, or in direct contact with, at least one platinum group metal crystallite having a crystallite size of about 1 nm or greater.

26 . The method of claim 25 , wherein the at least one portion of the copper-alumina spinel phase is within about 50 nm of the at least one platinum group metal crystallite.

27 . The method of claim 20 , wherein the step of thermally treating the catalyst composition comprises heating the catalyst composition at a temperature of at least 600° C. in an oxidizing environment.

28 . The method of claim 20 , wherein the porous alumina material comprising predominantly alumina mixed with copper oxide is formed by a method comprising either co-precipitating a mixture of a soluble aluminum salt and a soluble copper salt or impregnating a copper salt onto an alumina support.

Assignees

• Basf Corp

Inventors

• Ilinich Oleg
• Hoke Jeffrey B

Classifications

• B01D53/9472

  in different zones · CPC title

• B01D2255/9032

  Two zones · CPC title

• B01D53/9468

  in different layers · CPC title

• B01J23/44

  Palladium · CPC title

• F01N2370/00

  Selection of materials for exhaust purification · CPC title