# US 10,500,562 B2 · Zirconia-based compositions for use in passive NOx adsorber devices

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- Number: US 10,500,562 B2
- Document ID: US10500562B2
- Status: Granted
- Kind: B2
- Application number: 15/945,770
- Filed: 2018-04-05
- Published: 2019-10-10
- Granted: 2019-12-10
- Earliest claimed: 2018-04-05
- Assignees: Magnesium Elektron Limited; University of Kentucky Research Foundation
- Applicants: Magnesium Elektron Limited; University of Kentucky Research Foundation
- Inventors: Deborah Jayne Harris; David Alastair Scapens; John G. Darab; Mark Crocker; Yaying Ji
- Web page: https://patentgrep.com/patent/US10500562B2

## CPC

- B01J 20/06: comprising oxides or hydroxides of metals not provided for in group B01J20/04
- B01D 53/04: with stationary adsorbents {(B01D53/025 takes precedence)}
- B01D 53/9413: {Processes characterised by a specific catalyst}
- B01D 53/9418: {for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas}
- B01D 53/9422: {for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR)}
- B01D 53/9481: {Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start}
- B01J 20/0225: {Compounds of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt}
- B01J 20/3204: {Inorganic carriers, supports or substrates}
- B01J 20/3214: {characterised by the method for obtaining this coating or impregnating}
- B01J 20/3236: {containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts}
- B01D 2253/1122: Metals
- B01D 2253/25: Coated, impregnated or composite adsorbents
- B01D 2255/1021: Platinum
- B01D 2255/1023: Palladium
- B01D 2255/2065: Cerium
- B01D 2255/2066: Praseodymium
- B01D 2255/20715: Zirconium
- B01D 2255/2073: Manganese
- B01D 2255/20738: Iron
- B01D 2255/20776: Tungsten
- B01D 2255/30: Silica
- B01D 2255/407: Zr-Ce mixed oxides
- B01D 2255/91: NOx-storage component incorporated in the catalyst
- B01D 2257/404: Nitrogen oxides other than dinitrogen oxide
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)

## Abstract

A passive NOX adsorbent includes: palladium, platinum or a mixture thereof and a mixed or composite oxide including the following elements in percentage by weight, expressed in terms of oxide: 10-90% by weight zirconium and 0.1-50% by weight of least one of the following: a transition metal or a lanthanide series element other than Ce. Although the passive NOX adsorbent can include Ce in an amount ranging from 0.1 to 20% by weight expressed in terms of oxide, advantages are obtained particularly in the case of low-Ce or a substantially Ce-free passive NOx adsorbent.

## Claims

### Claim 1

A passive NOX adsorbent comprising: palladium, platinum or a mixture thereof and a mixed or composite oxide comprising the following elements in percentage by weight, expressed in terms of oxide: 10-90% by weight zirconium; and 0.1-50% by weight of least one of the following: a lanthanide series element other than Ce, comprising Pr; and a transition metal comprising at least one of the following metals selected from W, Mn, and Fe.

### Claim 2 (depends on 1)

A passive NOx adsorbent according to claim 1 further comprising at least one of Y, La and Nd as said lanthanide series element other than Ce.

### Claim 3 (depends on 1)

A passive NOx adsorbent according to claim 1, comprising Mn as said transition metal in an amount of 0.1 to 20% by weight and Pr as said lanthanide series element other than Ce in an amount of 0.5 to 30% by weight, wherein a total amount of Pr and Mn is not more than 50% by weight.

### Claim 4 (depends on 3)

A passive NOx adsorbent according to claim 3 further comprising at least one of W and Fe as said transition metal.

### Claim 5 (depends on 3)

A passive NOx adsorbent according to claim 3 further including at least one of Y, La and Nd as said lanthanide series element other than Ce.

### Claim 6 (depends on 3)

A passive NOx adsorbent according to claim 3 further comprising an element from Group 14 of the Periodic Table in an amount ranging from 0.1 to 20% by weight expressed in terms of oxide.

### Claim 7 (depends on 1)

A passive NOx adsorbent according to claim 1 comprising Ce in an amount ranging from 0.1% to not more than 20% by weight expressed in terms of oxide.

### Claim 8 (depends on 1)

A passive NOx adsorbent according to claim 1 comprising Ce in an amount ranging from 0.5 to not more than 5% by weight expressed in terms of oxide.

### Claim 9 (depends on 1)

A passive NOx adsorbent according to claim 1 with the proviso that the passive NOx adsorbent is substantially free of Ce.

### Claim 10 (depends on 1)

A passive NOx adsorbent according to claim 1 with a minimum fresh NOx storage capacity of 7.5 μmol/g after 5 minutes at 120° C.

### Claim 11 (depends on 1)

A passive NOx adsorbent according to claim 1 with a minimum aged NOx storage capacity of 5 μmol/g after 5 minutes at 120° C.

### Claim 12 (depends on 1)

A passive NOx adsorbent according to claim 1 in which the mixed or composite oxide includes Mn as said at least one transition metal and optional Ce, with a minimum fresh NOx storage capacity of at least 40 μmol/g after 5 minutes at 120° C.

### Claim 13 (depends on 1)

A passive NOx adsorbent according to claim 1 in which the mixed or composite oxide includes Mn as said at least one transition metal and optional Ce, with a minimum aged NOx storage capacity of at least 19 μmol/g after 5 minutes at 120° C.

### Claim 14 (depends on 1)

A passive NOx adsorbent according to claim 1 in which the mixed or composite oxide includes Mn as said at least one transition metal, with a minimum fresh NOx storage capacity of at least 50 μmol/g after 5 minutes at 120° C.

### Claim 15 (depends on 1)

A passive NOx adsorbent according to claim 1 in which the mixed or composite oxide includes Mn as said at least one transition metal, with a minimum aged NOx storage capacity of at least 45 μmol/g after 5 minutes at 120° C.

### Claim 16 (depends on 1)

A passive NOx adsorbent according to claim 1 in combination with a Selective Catalytic Reduction catalyst.

### Claim 17 (depends on 1)

A monolithic substrate supporting a washcoat, said washcoat comprising said passive NOx adsorbent according to claim 1.

### Claim 18 (depends on 1)

A method for reducing nitrogen oxides (NOx) present in a lean gas stream comprising at least one of nitric oxide (NO) and nitrogen dioxide (NO2), comprising the steps of:
(i) providing the passive NOx adsorbent according to claim 1 in the lean gas stream;
(ii) adsorbing NOx from the lean gas stream on or in the passive NOx adsorbent at a temperature below 200° C.;
(iii) thermally net desorbing NOX from the passive NOx adsorbent in the lean gas stream at 200° C. and above;
(iv) catalytically reducing the NOX on a downstream catalyst situated downstream of the passive NOX adsorbent, with at least one of the following reductants: a nitrogenous reductant, a hydrocarbon reductant, hydrogen and a mixture thereof.

### Claim 19 (depends on 18)

A method according to claim 18 wherein the lean gas stream emanates from a gasoline fueled or diesel fueled engine.