ZIRCONIA-BASED COMPOSITIONS FOR USE IN PASSIVE NOx ADSORBER DEVICES

Patent metadata

Field	Value
Publication number	US-2020101436-A1
Application number	US-201916702344-A
Country	US
Kind code	A1
Filing date	Dec 3, 2019
Priority date	Apr 5, 2018
Publication date	Apr 2, 2020
Grant date	—

Abstract

A passive NO X 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 NO X 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.

First claim

1 - 20 . (canceled)

21 . 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.

22 . A passive NOx adsorbent according to claim 21 further comprising at least one of Y, La and Nd as said lanthanide series element other than Ce.

23 . A passive NOx adsorbent according to claim 21 , 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.

24 . A passive NOx adsorbent according to claim 23 further comprising at least one of W and Fe as said transition metal.

25 . A passive NOx adsorbent according to claim 23 further including at least one of Y, La and Nd as said lanthanide series element other than Ce.

26 . A passive NOx adsorbent according to claim 23 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.

27 . A passive NOx adsorbent according to claim 21 comprising Ce in an amount ranging from 0.1% to not more than 20% by weight expressed in terms of oxide.

28 . A passive NOx adsorbent according to claim 21 comprising Ce in an amount ranging from 0.5 to not more than 5% by weight expressed in terms of oxide.

29 . A passive NOx adsorbent according to claim 21 with the proviso that the passive NOx adsorbent is substantially free of Ce.

30 . A passive NOx adsorbent according to claim 21 with a minimum fresh NOx storage capacity of 7.5 μmol/g after 5 minutes at 120° C.

31 . A passive NOx adsorbent according to claim 21 with a minimum aged NOx storage capacity of 5 μmol/g after 5 minutes at 120° C.

32 . A passive NOx adsorbent according to claim 21 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.

33 . A passive NOx adsorbent according to claim 21 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.

34 . A passive NOx adsorbent according to claim 21 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.

35 . A passive NOx adsorbent according to claim 21 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.

36 . A monolithic substrate supporting a washcoat, said washcoat comprising said passive NOx adsorbent according to claim 21 .

37 . A passive NOx adsorbent according to claim 21 in combination with a Selective Catalytic Reduction catalyst.

38 . A method for reducing nitrogen oxides (NOx) present in a lean gas stream comprising at least one of nitric oxide (NO) and nitrogen dioxide (NO 2 ), comprising the steps of:
(i) providing the passive NOx adsorbent according to claim 21 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.

39 . A method according to claim 38 wherein the lean gas stream emanates from a gasoline fueled or diesel fueled engine.

Assignees

• Magnesium Elektron Ltd
• Univ Kentucky Res Found

Inventors

• Harris Deborah Jayne
• Scapens David Alastair
• Darab John G
• Crocker Mark
• Ji Yaying

Classifications

• B01D2253/25

  Coated, impregnated or composite adsorbents · CPC title

• B01D53/9422

  for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR) · CPC title

• B01D53/9413

  Processes characterised by a specific catalyst · CPC title

• B01D53/9418

  for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas · CPC title

• B01J20/06 Primary

  comprising oxides or hydroxides of metals not provided for in group B01J20/04 · CPC title