CA2368378A1 - Selective catalytic oxidation of co in presence of h2 - Google Patents

Selective catalytic oxidation of co in presence of h2 Download PDF

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Publication number
CA2368378A1
CA2368378A1 CA002368378A CA2368378A CA2368378A1 CA 2368378 A1 CA2368378 A1 CA 2368378A1 CA 002368378 A CA002368378 A CA 002368378A CA 2368378 A CA2368378 A CA 2368378A CA 2368378 A1 CA2368378 A1 CA 2368378A1
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CA
Canada
Prior art keywords
oxide
catalyst
mixture
weight
gold
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002368378A
Other languages
French (fr)
Inventor
Bojidara Grigorova
John Mellor
Atanas Palazov
Fourie Greyling
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Anglo American Research Laboratories Pty Ltd
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2368378A1 publication Critical patent/CA2368378A1/en
Abandoned legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8933Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/8966Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with germanium, tin or lead
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66Silver or gold
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/56Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
    • C01B3/58Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids including a catalytic reaction
    • C01B3/583Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids including a catalytic reaction the reaction being the selective oxidation of carbon monoxide
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/0435Catalytic purification
    • C01B2203/044Selective oxidation of carbon monoxide
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/0465Composition of the impurity
    • C01B2203/047Composition of the impurity the impurity being carbon monoxide

Abstract

A catalyst which comprises gold, a transition metal oxide to which the gold is complexed and tin oxide captured on an oxide support which comprises a mixture of cerium oxide and titanium dioxide. The tin oxide is present in an amount of less than 0,4 % by weight of the catalyst. The catalyst has particular application in selectively oxidising carbon monoxide in a carbon monoxide/hydrogen mixture.

Description

BACKGROUND OF THE INVENTION
This invention relates to catalytic oxidation.
Fuel cells are electrochemical devices for continuously converting chemical energy into direct-current electricity. The cell consists of two electronic-conductor electrodes separated by an ionic conducting electrolyte with provision for the continuous flow of fuel, oxidant and reaction product into and out of the cell. The fuel may be gaseous or a liquid; the electrolyte liquid or solid; and the oxidant is gaseous. The electrodes are solid, but may be porous and contain a catalyst. Fuel cells differ from batteries in that electricity is produced from chemical fuels fed to them as needed.
One of the fuels which is used in a fuel cell is hydrogen. A contaminant in many sources of hydrogen is carbon monoxide which tends to poison the electrodes. Carbon dioxide, on the other hand, does not poison the electrodes of a fuel cell and it is therefore desirable to oxidise as much of the carbon monoxide to carbon dioxide before such hydrogen is fed to the fuel cell. One of the problems encountered in oxidising carbon monoxide to carbon dioxide is that there is simultaneous oxidation of the hydrogen. Selective oxidation of the carbon monoxide is difficult to achieve.
CONFIRMATION COP~I

_ 7 _ SUMMARY OF THE INVENTION
According to the invention, a method of selectively oxidising carbon monoxide in a carbon monoxide/hydrogen mixture comprises contacting the mixture with a suitable oxidant, generally oxygen, in the presence of a catalyst which comprises gold, a transition metal oxide, preferably cobalt oxide, to which the gold is complexed, and tin oxide captured on an oxide support comprising a mixture of cerium oxide and titanium dioxide, the tin oxide being present in an amount of less than 0,4% by weight of the catalyst.
According to another aspect of the invention, there is provided a catalyst which comprises gold, a transition metal oxide, preferably cobalt oxide, to which the gold is complexed, and tin oxide captured on an oxide support comprising a mixture of cerium oxide and titanium dioxide, the tin oxide being present in an amount of less than 0,4% by weight of the catalyst. The complexing of the gold and the transition metal oxide includes both chemical and physical bonding. Some such complexing of the tin oxide and the gold may also be present.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph showing CO oxidation of a gas containing CO, H2 and O2;
and Figure 2 is a graph showing HZ oxidation of a gas containing CO, H2 and O2.
DESCRIPTION OF EMBODIMENTS
It has been found that the gold-based catalyst described above is particularly effective in the selective oxidation of carbon monoxide in a mixture of carbon monoxide and hydrogen. "Selective" means that the oxidation of the carbon _ 3 _ monoxide takes place in preference to that of the hydrogen. Some oxidation of the hydrogen will occur.
The oxidation of the mixture will take place in the presence of an oxidant such as oxygen and will typically take place at a temperature in the range 80 to 130°C.
The ratio of cerium oxide to titanium dioxide in the oxide support will generally be in the range of 4:1 to 5:1 on a weight basis.
The catalyst of the invention is further characterised by containing tin oxide. It is important that this oxide is present in a relatively low amount, i.e. 0,4 percent by weight of the catalyst or less. Preferably, such oxide is present in an amount of 0,03 to 0,3 percent by weight of the catalyst.
The oxide support may be made by providing a particulate mixture of the cerium oxide and titanium dioxide and, drying the mixture. The mixture will be in finely particulate form and will typically have a surface area of approximately 80 to 200 m2/g.
The catalyst of the invention may be made by methods described in the art.
Preferably, however, the catalyst is made by a method which includes the steps of providing a mixture of cerium oxide and titanium oxide, impregnating the mixture with a transition metal solution and optionally a tin solution, drying the impregnated oxide mixture, heating the impregnated oxide mixture at a temperature of at least 250°C in the presence of oxygen, contacting the thus treated oxide mixture with a gold solution at a pH above 12, decreasing the pH
of the gold solution to a pH in the range 7 to 8,5, causing gold to precipitate on to the oxide mixture, optionally drying the thus treated oxide mixture and heating the treated oxide mixture at a temperature of at least 250°C in the presence of oxygen.

An example of a preferred catalyst of the invention has the following composition (all percentages by weight):
83 % CeOz 15 % Ti02 0,3% Sn02 1 % Au 1 % Co, as an oxide.
The catalyst may be made as follows:
42g of Ce02 and 8g Ti02 are mixed for 10 minutes in an automatic mixer. The mixed oxides are dried at 120°C for 30 minutes and impregnated with 22,5m1 of 0,4 molar Co(N03)z and 10,5m1 of 0,1 molar SnC~2 solutions at 50°C.
The so formed sludge is dried at 120°C for 12 hours and impregnated with 21 ml of 0,13 molar HAuC/4. The material is washed with water and dried at 120°C
for 3 hours and calcined at 400°C for 30 minutes.
The catalyst is preferably made as follows:
Stage One Powdered cerium oxide and titanium oxide are accurately measured into a 100m1 sample bottle and mixed in a mixer mill for 10 minutes. This mixture is heated at 120°C for 30 minutes.
Solutions of cobalt nitrate and tin nitrate are introduced into a vessel and heated to 80°C. The heated mixture of cerium and titanium oxides, the support for the catalyst, is then added under constant stirring.

_ j _ The pressure in the mixing vessel is reduced and water is distilled off at a constant temperature of 65°C over a 4 hour period.
The oxide support. impregnated with cobalt and tin nitrates, is dried at 120°C
for 2 hours.
The dried oxide support is sieved through a 35 micron mesh sieve and then heated under air at 300°C for 6 hours. This has the effect of converting the cobalt and tin nitrates to their oxides.
Stage Two Hydrogen tetrachloroaurate solution is added to 500m1 potassium hydroxide solution at pH 13. The combined solution has a pH of just below 13.
The temperature of the solution is increased to 60°C and the preheated oxide support, impregnated with the cobalt and tin oxides, is added to form a slurry.
The pH of the slurry is reduced to 8 by addition of 0,1 M HN03.
Magnesium citrate solution (six times the mole equivalent of the hydrogen tetrachloroaurate) is added to the slurry at a constant rate over a 30 minute period. The slurry is maintained at pH 8 and 60°C over a 60 minute period.
The slurry is filtered producing a filtered catalyst. The filtered catalyst is re-slurried in de-ionised water and stirred for a further 30 minutes before being filtered and washed with de-ionised water.
The catalyst is then dried at 120°C under air for 2 hours. The dried catalyst is sieved to -35~m and calcined at 450°C under 5% Oz for 3 hours.
The catalyst is stored prior to use.

The selective oxidation of carbon monoxide in a mixture containing 0.5 percent CO, 2 percent H2, 0,8 percent O2, the balance being nitrogen, was evaluated using a catalyst of the type described above, designated FC6, and a similar catalyst, except that the tin oxide was omitted, designated FC2. The oxidation of CO is shown in Figure 1 and the oxidation of H2 is shown in Figure 2.
It will be noted from the graphs that the carbon monoxide oxidation of the catalyst without the tin oxide achieved excellent carbon monoxide oxidation, but also significant hydrogen oxidation, particularly at higher temperatures.
In contrast, at higher temperatures, the oxidation of the carbon monoxide in the presence of the catalyst of the invention approached that of the other catalyst but with significantly lower hydrogen oxidation.

Claims (14)

1. A method of selectively oxidising carbon monoxide in a carbon monoxide/hydrogen mixture comprises contacting the mixture with a suitable oxidant in the presence of a catalyst which comprises gold, a transition metal oxide, to which the gold is complexed, and tin oxide captured on an oxide support comprising a mixture of cerium oxide and titanium dioxide, the tin oxide being present in an amount of less than 0,4% by weight of the catalyst.
2. A method according to claim 1 wherein the transition metal oxide is cobalt oxide.
3. A method according to claim 1 or claim 2, wherein the ratio of cerium oxide to titanium dioxide is in the range 4:1 to 5:1 on a weight basis.
4. A method according to any one of claims 1 to 3, wherein the tin oxide is present in an amount of 0,03 to 0,3 percent by weight of the catalyst.
5. A method according to claim 1, wherein the catalyst has the composition (all percentages being by weight):
83% CeO2 15% TiO2 0,3% SnO2 1% Au 1% Co, as an oxide.
6. A method according to any one of the preceding claims wherein the oxidant is oxygen.
7. A method according to any one of the preceding claims wherein the oxidation takes place at a temperature in the range 80 to 130°C.
8. A catalyst comprising gold a transition metal oxide to which the gold is complexed, and tin oxide captured on an oxide support comprising a mixture of cerium oxide and titanium oxide, the tin oxide being present in an amount of less than 0,4% by weight of the catalyst.
9. A catalyst according to claim 8, wherein the transition metal oxide is cobalt oxide.
10. A catalyst according to claim 8 or claim 9, wherein the ratio of cerium oxide to titanium dioxide is in the range 4:1 to 5:1 on a weight basis.
11. A catalyst according to any one of claims 8 to 10, wherein the tin oxide is present in an amount of 0,03 to 0,3 percent by weight of the catalyst.
12. A catalyst according to claim 8, which has the composition (all percentages by weight):
83 % CeO2 15 % TiO2 0,3% SnO2 1% Au 1% Co, as an oxide.
13. A method according to claim 1, substantially as herein described.
14. A catalyst according to claim 8, substantially as herein described.
CA002368378A 1999-04-01 2000-03-31 Selective catalytic oxidation of co in presence of h2 Abandoned CA2368378A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ZA99/2510 1999-04-01
ZA992510 1999-04-01
PCT/IB2000/000390 WO2000059631A1 (en) 1999-04-01 2000-03-31 Selective catalytic oxidation of co in presence of h2

Publications (1)

Publication Number Publication Date
CA2368378A1 true CA2368378A1 (en) 2000-10-12

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ID=25587657

Family Applications (1)

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CA002368378A Abandoned CA2368378A1 (en) 1999-04-01 2000-03-31 Selective catalytic oxidation of co in presence of h2

Country Status (7)

Country Link
EP (1) EP1165229A1 (en)
JP (1) JP2002541043A (en)
AU (1) AU767170B2 (en)
CA (1) CA2368378A1 (en)
IL (1) IL145713A0 (en)
RU (1) RU2001129358A (en)
WO (1) WO2000059631A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008006210A1 (en) * 2006-07-11 2008-01-17 Tekion, Inc. Catalysts including metal oxide for organic fuel cells

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100500293C (en) * 2007-04-13 2009-06-17 中国科学院山西煤炭化学研究所 Composite CeO2-CoOx oxide carrier and its preparation process

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08295502A (en) * 1995-04-25 1996-11-12 Agency Of Ind Science & Technol Method for removing carbon monoxide in hydrogen-containing gas with gold catalyst
BG62687B1 (en) * 1997-05-15 2000-05-31 "Ламан-Консулт"Оод Gold catalyst for the oxidation of carbon oxide and hydrocarbons, reduction of nitrogen oxides and ozone decomposition

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008006210A1 (en) * 2006-07-11 2008-01-17 Tekion, Inc. Catalysts including metal oxide for organic fuel cells

Also Published As

Publication number Publication date
AU767170B2 (en) 2003-11-06
EP1165229A1 (en) 2002-01-02
AU3448700A (en) 2000-10-23
WO2000059631A1 (en) 2000-10-12
IL145713A0 (en) 2002-07-25
RU2001129358A (en) 2004-01-27
JP2002541043A (en) 2002-12-03

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FZDE Discontinued