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EP0115290A2
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Doubly promoted platinum group metal catalysts for emission control
Assignee: WR Grace and Co
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Filing: 1984-01-17
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Granted: —
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Expires: 2004-01-17
Abstract
Abstract Catalysts are made from supports which are doubly promoted with ceria and an alkali metal oxide by adding these promoters and the catalytic noble metal components in a specified order. The ceria is first applied to the support. It can be applied in a salt form such as cerous nitrate. this impregnated support is then calcined to form a deposit of ceria. Next, solutions bearing the noble metals are applied to the ceria-promoted support and with these solutions the alkali metal component is applied. After subsequent elevated temperature activation, the alkali metal component is converted to an alkali metal oxide and the noble metals are converted into their metallic or oxide form. When lithium is chosen as the alkali metal promoter, it can alternatively be applied to the support along with the initial ceria promoter. After calcining the support to yield the ceria and lithia promoters, the noble metals can then be deposited and subsequently activated at an elevated temperature. Using this process it is possible to have the noble metals deposited on the support so that their penetration depth is less than 300 microns as measured by the SnC1 2 solution staining method to provide an effective three-way catalyst suitable for use in auto emission control.
Inventors
- 👤 Gwan Kim
- 👤 Michael Vance Ernest
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 10:55
CPC Classifications
B; B01; B01J; B01J23/00; B01J23/38; B01J23/54; B01J23/56; B01J23/63; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9445; B01D53/945; B01J23/58; Y; Y02; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
100 words
A method of making a catalyst suitable for use as a three-way catalyst for auto emission control comprising the steps of a) impregnating a calcined or activated alumina- support with a cerous salt solution; b) air drying and air calcining the impregnated support to obtain a ceria impregnated support; c) impregnating the ceria impregnated support with solutions bearing noble metals and at least one alkali metal at a temperature below about 250°C to form a catalyst; d) air drying the catalyst at a temperature of about 100-150°C; and e) activating the catalyst with hydrogen at a temperature of about 250-550°C.
Claim 2
Independent Claim
100 words
A method of making a catalyst suitable for use as a three-way catalyst for auto emission control comprising the steps of a) impregnating a calcined or activated alumina- support with a cerous salt solution; b) air drying and air calcining the impregnated support to obtain a ceria impregnated support; c) impregnating the ceria impregnated support with solutions bearing noble metals and at least one alkali metal at a temperature below about 250°C to form a catalyst; d) air drying the catalyst at a temperature of about 100-150°C; and e) activating the catalyst with hydrogen at a temperature of about 250-550°C.
Claim 3
Dependent Claim
44 words
The method according to Claim 1, wherein the calcined alumina of step (a) has been calcined at a temperature of about 950-1050°C and wherein step (b) comprises drying at a temperature of about 100-150°C followed by air calcination at a temperature of about 500-800°C.
Claim 4
Dependent Claim
44 words
The method according to Claim 1, wherein the calcined alumina of step (a) has been activated at a temperature of about 300-600°C and wherein step (b) comprises drying at a temperature of about 100-150°C followed by air calcination at a temperature of about 950-1050°C.
Claim 5
Dependent Claim
24 words
The method according to Claim 1, wherein the activating in step (e) is done at a temperature of about 400°C for about 1 hour.
Claim 6
Dependent Claim
21 words
The method according to Claim 1, wherein the amount of ceria impregnated is about 1-10 weight percent C e0 2 .
Claim 7
Dependent Claim
21 words
The method according to Claim 5, wherein the amount of ceria impregnated is about 2-6 weight percent C e0 2 .
Claim 8
Dependent Claim
30 words
The method according to Claim 1, wherein the alkali metal expressed as the oxide M 2 0 is present in an effective amount of up to about 5 weight percent.
Claim 9
Dependent Claim
22 words
The method according to Claim 1, wherein the noble metals in step (c) are provided in the form of sulfito complex ions.
Claim 10
Dependent Claim
19 words
The method according to Claim 1, wherein the impregnation in step (c) is done in multiple steps of impregnation.
Claim 11
Dependent Claim
13 words
The method according to Claim 1, wherein the support is an alumina pellet.
Claim 12
Dependent Claim
13 words
The method according to Claim 1, wherein the support is an alumina powder.
Claim 13
Dependent Claim
12 words
The method according to Claim 1, wherein the alkali metal is sodium.
Claim 14
Dependent Claim
17 words
The method according to Claim 1, wherein the noble metal is platinum, palladium, rhodium or mixtures thereof.
Claim 15
Dependent Claim
13 words
The method according to Claim 13, wherein both platinum and palladium are present.
Claim 16
Dependent Claim
9 words
A catalyst made by the method of Claim 1.
Claim 17
Independent Claim
93 words
A method of making a catalyst which is suitable for use as a three-way catalyst for auto emission comprising the steps of a) impregnating an activated alumina support with a solution containing a cerous salt and a lithium salt; b) air drying and air calcining the impregnated support to obtain a ceria-lithia impregnated support; c) impregnating the ceria-lithia impregnated support with solutions bearing noble metals to form a catalyst; d) air drying the catalyst at a temperature of about 100-150°C; and e) activating the catalyst with hydrogen at a temperature of about 250-550°C.
Claim 18
Independent Claim
93 words
A method of making a catalyst which is suitable for use as a three-way catalyst for auto emission comprising the steps of a) impregnating an activated alumina support with a solution containing a cerous salt and a lithium salt; b) air drying and air calcining the impregnated support to obtain a ceria-lithia impregnated support; c) impregnating the ceria-lithia impregnated support with solutions bearing noble metals to form a catalyst; d) air drying the catalyst at a temperature of about 100-150°C; and e) activating the catalyst with hydrogen at a temperature of about 250-550°C.
Claim 19
Dependent Claim
24 words
The method according to Claim 16, wherein the activating in step (e) is done at a temperature of about 400°C for about 1 hour.
Claim 20
Dependent Claim
19 words
The method according to Claim 16, wherein the amount of ceria impregnated is about 1-10 wt.% Ce0 2 .
Claim 21
Dependent Claim
19 words
The method according to Claim 18, wherein the amount of ceria impregnated is about 2-6 wt.% CeO 2 .
Claim 22
Dependent Claim
21 words
The method according to Claim 16, wherein the amount of lithia impregnated is up to about 5 wt.% Li 2 0.
Claim 23
Dependent Claim
19 words
The method according to Claim 20, wherein the amount of lithia impregnated is about 0.5-3 wt.% Li 2 0.
Claim 24
Dependent Claim
22 words
The method according to Claim 16, wherein the noble metals in step (c) are provided in the form of sulfito complex ions.
Claim 25
Dependent Claim
19 words
The method according to Claim 16, wherein the impregnation in step (c) is done in multiple steps of impregnation.
Claim 26
Dependent Claim
13 words
The method according to Claim 16, wherein the support is an alumina pellet.
Claim 27
Dependent Claim
13 words
The method according to Claim 16, wherein the support is an alumina powder.
Claim 28
Dependent Claim
9 words
A catalyst made by the method of Claim 16.
Claim 29
Dependent Claim
74 words
A catalyst suitable for use as a three-way catalyst for auto emission control comprising an alumina support having impregnated thereon about 2-6% by weight of ceria as a promoter, up to about 5% by weight of an alkali metal oxide as a promoter, and a catalytically effective amount of noble metals, said noble metals penetrating the alumina support to a distance less than 300 microns as measured by the SnCl 2 solution staining method.
Claim 30
Dependent Claim
74 words
A catalyst suitable for use as a three-way catalyst for auto emission control comprising an alumina support having impregnated thereon about 2-6% by weight of ceria as a promoter, up to about 5% by weight of an alkali metal oxide as a promoter, and a catalytically effective amount of noble metals, said noble metals penetrating the alumina support to a distance less than 300 microns as measured by the SnCl 2 solution staining method.
Claim 31
Dependent Claim
15 words
A catalyst according to Claim 27, wherein the alkali metal oxide is Na 2 0.
Claim 32
Dependent Claim
15 words
A catalyst according to Claim 27, wherein the alkali metal oxide is Li 2 0.
References Cited (Backward Citations)
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