Precious metal grid for catalyzing gas phase reactions

Patent metadata

Field	Value
Publication number	US-12350657-B2
Application number	US-202117996045-A
Country	US
Kind code	B2
Filing date	Apr 22, 2021
Priority date	Apr 22, 2020
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

The invention relates to a wire made of platinum group metals for producing grid catalysts comprising platinum and rhodium. The invention is characterized in that the wire is made as a sheathed wire and consists of a core and one or more sheaths arranged one over the other outwards from the core in a radially symmetrical manner, and the rhodium concentration in the outermost sheath is lower than the rhodium concentration in the sheath or core arranged directly under the outermost sheath.

First claim

The invention claimed is:

1. A wire consisting of platinum group metals for producing grid catalysts containing at least platinum and rhodium, wherein the wire is made as a sheath wire and consists of a core and one or more sheaths arranged one over the other outwards from the core in a radially symmetrical manner, and the rhodium concentration in the outermost sheath is lower than the rhodium concentration in the
core, if the sheath wire only consists of a core and a sheath, or
sheath, if the sheath wire consists of a core and two or more sheaths,
arranged directly under the outermost sheath, and the rhodium concentration in the outermost sheath is 1 wt % to 3 wt %, and the rhodium concentration in the sheath or core arranged under the outermost sheath is in the range of 5 wt % to 20 wt %, and the thickness of the outermost sheath is 1 μm to 10 μm.

2. The wire according to claim 1 , wherein the wire consists of a core and a sheath.

3. The wire according to claim 1 , wherein the sheath wire consists of a core and two or more sheaths arranged one over the other outwards from the core in a radially symmetrical manner, and the core consists of at least 92 wt % platinum and/or palladium.

4. A grid catalyst for catalyzing gas phase reactions, wherein the grid catalyst comprises a mesh containing a wire according to claim 1 .

5. The grid catalyst according to claim 4 , wherein the mesh of the grid catalyst is weft-knitted.

6. A method for producing a grid catalyst according to claim 4 , comprising the steps of:
a. providing a bolt, comprising platinum and/or palladium,
b. providing a tube or a plurality of tubes, comprising platinum and rhodium, wherein the inner diameter of the thinnest tube is selected such that the thinnest tube can be pushed flush over the bolt, and the diameters of the further tubes are selected such that they can be pushed flush one over the other, and the outermost tube has a lower rhodium concentration than the sheath or core arranged under the outermost tube
c. pushing the tubes and the bolt one over the other, starting with the pushing of the thinnest tube over the bolt, after which the tubes are pushed on successively with increasing diameter, and connecting the bolt to the tube or tubes thereby creating a blank
d. annealing and subsequently cold-rolling the blank; this step can be repeated several times
e. wire-drawing the blank to the desired wire thickness
f. weft-knitting the catalyst grid from the wire.

7. The method according to claim 6 , wherein the bolt is connected (method step b) to the tube or to the tubes by means of a tube puller.

8. A method for oxidizing ammonia, wherein the oxidation is catalyzed by at least one catalyst grid according to claim 4 .

9. The wire according to claim 1 , wherein the rhodium concentration in the sheath or core arranged under the outermost sheath is in the range of 8 wt % to 12 wt %.

10. The wire according to claim 9 , wherein the thickness of the outermost sheath is 1 μm to 5 μm.

11. The wire according to claim 1 , wherein the thickness of the outermost sheath is 1 μm to 5 μm.

12. The wire according to claim 3 , wherein the core consists of at least 97 wt % platinum and/or palladium.

Assignees

• Umicore Ag & Co Kg

Inventors

• Born Dirk
• Wiser Artur
• Zeuner Stefan

Classifications

• B01J35/396

  Distribution of the active metal ingredient · CPC title

• B01J35/19

  Catalysts containing parts with different compositions · CPC title

• C01B21/265

  characterised by the catalyst · CPC title

• B01J37/0009

  Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst · CPC title

• B01J23/464 Primary

  Rhodium · CPC title