Catalyst for reducing ammonia emissions

Patent metadata

Field	Value
Publication number	US-12508576-B2
Application number	US-202017636554-A
Country	US
Kind code	B2
Filing date	Aug 18, 2020
Priority date	Aug 20, 2019
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

The present invention relates to a composition comprising platinum supported on titanium oxide, the platinum particles having an average particle diameter of 50-200 nm. The composition has a surprisingly low light-off temperature for the ammonia oxidation and a high selectivity for oxidation to N2.

First claim

The invention claimed is:

1 . Composition comprising platinum in the form of platinum particles supported on metal oxide A, characterized in that the platinum particles have an average particle diameter of 50-200 nm, wherein metal oxide A is titanium oxide.

2 . Composition according to claim 1 , characterized in that the platinum particles have an average particle diameter of 80-120 nm.

3 . Composition according to claim 1 , characterized in that the composition contains no further precious metal other than platinum.

4 . Composition according to claim 1 , characterized in that the titanium oxide comprises the crystalline phases anatase and rutile, and the anatase to rutile ratio is greater than 9:1.

5 . Composition according to claim 1 , characterized in that the platinum loading is 0.5-20% by weight based on the metal oxide A.

6 . Composition according to claim 1 , characterized in that the platinum loading is 3-8% by weight based on the metal oxide A.

7 . Composition according to claim 1 , characterized in that the metal oxide A contains silicon oxide, wherein the proportion of silicon oxide in the metal oxide A is 1 to 10% by weight.

8 . Composition, characterized in that it comprises a composition according to claim 1 and metal oxide B, wherein metal oxide B equals metal oxide A.

9 . Method for producing a composition according to claim 1 , characterized in that the platinum is deposited from a solution on the metal oxide A and the composition is subjected to a thermal treatment at 700° C. to 900° C. after drying.

10 . Catalyst comprising a composition according to claim 1 , characterized in that the composition is applied to a carrier substrate of length L.

11 . Catalyst according to claim 10 , characterized in that the composition is applied to a carrier substrate over at least 80% of the entire length L.

12 . Catalyst according to claim 10 , characterized in that the composition is applied to a carrier substrate over a length of 10% to 80% of the carrier substrate length L.

13 . Catalyst according to claim 10 , characterized in that the composition is applied to a carrier substrate together with another catalytically active composition that is active for SCR reaction.

14 . Catalyst according to claim 10 , characterized in that the composition and another catalytically active composition are arranged in different zones and/or layers.

15 . Catalyst according to claim 10 , characterized in that the carrier substrate is a ceramic or metallic substrate.

16 . Catalyst according to claim 10 , characterized in that the carrier substrate is a flowthrough substrate.

17 . Catalyst according to claim 16 , characterized in that the flowthrough substrate is a corrugated substrate.

18 . Catalyst according to claim 10 , characterized in that the carrier substrate is a filter substrate.

19 . Catalyst system, characterized in that it comprises a catalyst according to the invention in accordance with claim 10 .

20 . Method for reducing nitrogen oxides in exhaust gases of lean-burn internal combustion engines, wherein the exhaust gas is passed over an exhaust gas system that comprises a catalyst for the selective reduction of nitrogen oxides (SCR) and an ammonia slip catalyst (ASC) downstream of the exhaust gas stream, characterized in that the ASC is a catalyst according to the invention in accordance with claim 10 .

21 . Method according to claim 20 , characterized in that the SCR catalyst is a vanadium oxide-based catalyst or a zeolite-based catalyst of the Fe-zeolite or Cu-zeolite type.

Assignees

• Umicore Ag & Co Kg

Inventors

• Friedrich Birgit
• Keitl Gordon

Classifications

• F01N2510/063

  zeolites · 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

• B01J29/7049

  containing rare earth elements, titanium, zirconium, hafnium, zinc, cadmium, mercury, gallium, indium, thallium, tin or lead · CPC title

• F01N3/0814

  combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts · CPC title

• B01J23/40

  of the platinum group metals · CPC title