Catalyst

Patent metadata

Field	Value
Publication number	US-2019036128-A1
Application number	US-201716072946-A
Country	US
Kind code	A1
Filing date	Jan 26, 2017
Priority date	Jan 29, 2016
Publication date	Jan 31, 2019
Grant date	—

Abstract

A process for preparing a catalyst material, said catalyst material comprising a support material, a first metal and one or more second metals, wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group of transition metals and tin provided the second metal(s) is different to the first metal is disclosed. The process comprises depositing a silicon oxide before or after deposition of the second metal(s), alloying the first and second metals and subsequently removing silicon oxide. A catalyst material prepared by this process is also disclosed.

First claim

1 . A process for preparing a catalyst material, said catalyst material comprising a support material, a first metal and one or more second metals, wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group consisting of transition metals and tin, provided the second metal(s) is different to the first metal, said process comprising the steps:
(i) providing a catalyst material precursor comprising the first metal supported on the support material; (ii) depositing a silicon oxide precursor and one or more second metal precursors on the catalyst material precursor; (iii) carrying out a first heat treatment step to convert the silicon oxide precursor to silicon oxide; (iv) carrying out a second heat treatment step to alloy the first metal and the second metal(s); and (v) removal of at least some of the silicon oxide to give the catalyst material.

2 . A process according to claim 1 , wherein in step (ii) the silicon oxide precursor is deposited prior to the second metal precursor(s).

3 . A process according to claim 1 , wherein in step (ii) the second metal precursor(s) is deposited prior to the silicon oxide precursor.

4 . A process according to claim 1 , wherein the catalyst material comprises two or more second metals and wherein in step (ii) each second metal precursor is independently deposited either before or after the silicon oxide precursor.

5 . A process according to claim 1 , further comprising step (vi):
(vi) removal of some or all unalloyed second metal(s) and/or removal of a portion of alloyed second metal(s) from the surface of the catalyst material.

6 . A process according to claim 1 , wherein the first heat treatment step is carried out at a temperature in the range of 250° C. to 500° C.

7 . A process according to claim 1 , wherein the second heat treatment step is carried out at a temperature in the range of 350° C. to 1000° C.

8 . A process according to claim 1 , wherein the first and second heat treatment steps are carried out as a single sequential process, the second heat treatment step being a continuation of the first heat treatment step.

9 . A process according to claim 1 , wherein the first metal is platinum.

10 . A process according to claim 1 , wherein the second metal(s) is one or more metals selected from the group consisting of precious metals other than platinum and base metals.

11 . A process according to claim 10 , wherein the second metal(s) is selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, gold, silver, nickel, cobalt, chromium, copper, iron, zinc, niobium, tantalum, vanadium, tin and titanium.

12 . A process according to claim 11 , wherein second metal(s) is selected from the group consisting of nickel, cobalt, chromium, palladium, iridium, copper, iron, zinc, osmium, ruthenium, niobium, tantalum, vanadium, iridium, tin, titanium and rhodium.

13 . A process according to claim 12 , wherein the second metal(s) is selected from the group consisting of nickel, cobalt, chromium, palladium, iridium, copper, iron and zinc.

14 . A process according to claim 12 , wherein the second metal(s) is selected from the group consisting of osmium, ruthenium, niobium, tantalum, vanadium, iridium, tin, titanium and rhodium.

15 . A process according to claim 1 , wherein the support material is fibrous or particulate.

16 . A process according to claim 1 , wherein up to 5 wt % of silicon with respect to the weight of the catalyst material remains after step (v).

17 . (canceled)

18 . A cathode catalyst material comprising a support material, a first metal and one or more second metals, wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group consisting of nickel, cobalt, chromium, palladium, iridium, copper, iron and zinc, provided the first metal and second metal(s) are not the same, wherein the ratio of first metal to total second metal(s) is ≥1, and the CO metal area of the catalyst material, as measured by gas phase carbon monoxide (CO) chemisorption, is at least 56 m 2 /g of the platinum group metal components.

19 . An anode catalyst material comprising a support material, a first metal and one or more second metal(s), wherein the first metal and the second metal(s) are alloyed and wherein the first metal is a platinum group metal and the second metal(s) is selected from the group consisting of osmium, ruthenium, niobium, tantalum, vanadium, iridium, tin, titanium and rhodium, provided that the first metal and the second metal(s) are not the same, wherein the ratio of first metal to total second metal(s) is ≥0.5, and the CO metal area of the catalyst material, as measured by gas phase carbon monoxide (CO) chemisorption, is at least 18 m 2 /g of platinum group metal components.

20 . A catalyst layer comprising a catalyst material according to claim 18 .

21 . A cathode catalyst material according to claim 18 , wherein the first metal is platinum, ruthenium, rhodium, osmium or iridium.

22 . A cathode catalyst material according to claim 21 , wherein the first metal is platinum.

23 . A cathode catalyst material according to claim 18 , wherein the second metal(s) is selected from the group consisting of nickel, cobalt, chromium, iridium, copper, iron and zinc.

24 . A cathode catalyst material according to claim 23 , wherein the second metal is nickel.

25 . An anode catalyst material according to claim 19 , wherein the first metal is platinum, ruthenium, rhodium, osmium or iridium.

26 . An anode catalyst material according to claim 25 , wherein the first metal is platinum.

27 . An anode catalyst material according to claim 19 , wherein the second metal is rhodium.

28 . A catalyst layer comprising a catalyst material according to claim 19 .

Assignees

• Johnson Matthey Fuel Cells Ltd

Inventors

• Martinez Bonastre Alejandro
• Spikes Geoffrey Hugh
• O'Malley Rachel Louise

Classifications

• H01M4/9041

  Metals or alloys (H01M4/92 takes precedence) · CPC title

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title

• H01M4/8882 Primary

  Heat treatment, e.g. drying, baking · CPC title

• H01M4/921

  Alloys or mixtures with metallic elements · CPC title

• H01M4/925

  supported on carriers, e.g. powder carriers · CPC title