CA1065123A - Process for the oxidation of carbon monoxide and hydrocarbons - Google Patents
Process for the oxidation of carbon monoxide and hydrocarbonsInfo
- Publication number
- CA1065123A CA1065123A CA222,637A CA222637A CA1065123A CA 1065123 A CA1065123 A CA 1065123A CA 222637 A CA222637 A CA 222637A CA 1065123 A CA1065123 A CA 1065123A
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- Prior art keywords
- carrier
- oxidation
- shapes
- cerium
- alumina
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Combustion & Propulsion (AREA)
- Biomedical Technology (AREA)
- Environmental & Geological Engineering (AREA)
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- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
PROCESS FOR THE OXIDATION OF CARBON MONOXIDE
AND HYDROCARBONS.
ABSTRACT OF THE DISCLOSURE:
Carbon monoxide and hydrocarbons contained in exhaust gas of internal combustion engines are oxidized with oxygen-containing gas to carbon dioxide and water. The oxidation is effected at 150-800°C in contact with a carrier-supported catalyst, wherein alumina partially converted to .alpha.-Al2O3 is the carrier and cerium in oxide form is the catalytically active ingredient, the catalytically active ingredient constituting 0.2 to 10 weight % of the carrier being depo-sited thereon, The oxidation is more particularly carried out in contact with a carrier-supported catalyst being produced by compressing hydrous alumina or unstable anhydrous alumina into shapes;
annealing the shapes for 10 - 20 hours at 1000 - 1250°C;
impregnating the annealed shapes with an aqueous solution of a cerium salt of a readily decomposable acid; drying the cerium salt so applied to the shapes at 130 - 150°C; de-composing the dry cerium salt by gradually heating the shapes to temperatures within the range 200 and 300°C and 450 and 550°C, respectively; and annealing the resulting shapes containing cerium oxide at 700 - 900°C.
AND HYDROCARBONS.
ABSTRACT OF THE DISCLOSURE:
Carbon monoxide and hydrocarbons contained in exhaust gas of internal combustion engines are oxidized with oxygen-containing gas to carbon dioxide and water. The oxidation is effected at 150-800°C in contact with a carrier-supported catalyst, wherein alumina partially converted to .alpha.-Al2O3 is the carrier and cerium in oxide form is the catalytically active ingredient, the catalytically active ingredient constituting 0.2 to 10 weight % of the carrier being depo-sited thereon, The oxidation is more particularly carried out in contact with a carrier-supported catalyst being produced by compressing hydrous alumina or unstable anhydrous alumina into shapes;
annealing the shapes for 10 - 20 hours at 1000 - 1250°C;
impregnating the annealed shapes with an aqueous solution of a cerium salt of a readily decomposable acid; drying the cerium salt so applied to the shapes at 130 - 150°C; de-composing the dry cerium salt by gradually heating the shapes to temperatures within the range 200 and 300°C and 450 and 550°C, respectively; and annealing the resulting shapes containing cerium oxide at 700 - 900°C.
Description
~065~23 The present invention relates to the oxidation of carbon monoxide and hydrocarbons, especially of those being contained in the exhaust gas of internal combustion engines, with oxygen-containing gases to carbon dioxide and water.
Carbon monoxide and hydrocarbons are oxidized in contact with catalysts, wherein the active ingredients are either noble metals belonging to group VIII of the Periodic System or are mixed oxides, e.g. of copper, manganese and nickel, the mixed oxides, which are less costly, being preferred so as to enable wide use to be made of those catalysts, e.g. for the decontamination of automobile exhaust gas. The catalysts used to this end are required to be abrasionproof, to be thermally shockproof, to be sinter-proof, to have a low starting temperature, if possible lower than 200 C, and to have a constant activity, even if heated for pro-longed periods of time to temperatures of at least 800& .
United States Patent Specification 3 493 325 describes a catalyst deposited, e.g. on gel-like or activated alumina, for the catalytic oxidation of exhaust gas of internal combustion engines.
The active ingredients applied to the carrier are selected from oxides of copper~ nickel, cobalt, iron, chromium, manganese or mixtures thereof.
A further catalyst has been described in German Patent Specification 1 272 896, which is deposited on a carrier contain-ing at least 30 weight % of alumina together with alkali metal and alkaline earth metal oxides, and heat-resistant filler materials. The catalytically active ingredients inter alia include oxides of copper, nickelJ cobalt, manganese and cerium.
Carbon monoxide and hydrocarbons are oxidized in contact with catalysts, wherein the active ingredients are either noble metals belonging to group VIII of the Periodic System or are mixed oxides, e.g. of copper, manganese and nickel, the mixed oxides, which are less costly, being preferred so as to enable wide use to be made of those catalysts, e.g. for the decontamination of automobile exhaust gas. The catalysts used to this end are required to be abrasionproof, to be thermally shockproof, to be sinter-proof, to have a low starting temperature, if possible lower than 200 C, and to have a constant activity, even if heated for pro-longed periods of time to temperatures of at least 800& .
United States Patent Specification 3 493 325 describes a catalyst deposited, e.g. on gel-like or activated alumina, for the catalytic oxidation of exhaust gas of internal combustion engines.
The active ingredients applied to the carrier are selected from oxides of copper~ nickel, cobalt, iron, chromium, manganese or mixtures thereof.
A further catalyst has been described in German Patent Specification 1 272 896, which is deposited on a carrier contain-ing at least 30 weight % of alumina together with alkali metal and alkaline earth metal oxides, and heat-resistant filler materials. The catalytically active ingredients inter alia include oxides of copper, nickelJ cobalt, manganese and cerium.
- 2 -.. . . ..
~065~23 ~ ~
These prior art catalysts are not fully satisfactory, however, as their activity varies depending on whether they are contacted with an oxidizing or reducing gas. More particularly, they are highly active if contacted with a mixture consisting of `
the gas to undergo oxidation and a stoichiometric or slightly understoichiometric proportion of oxygen, whilst they are less active if contacted with a mixture containing an excess of oxygen.
In other words, it is necessary for those prior art catalysts to be contacted with a gas mixture containing a stoi- `
chiometric proportion of oxygen, based on the carbon monoxide hydrocarbons present in the gas mixture to undergo oxidation. This is more especially necessary in an attempt (a) to maintain the cat-alyst active and (b) to ensure complete combustion of the gas to undergo oxidation. It should be borne in mind, however, that the exhaust gases of internal combustion engines always contain variable `
proportions of carbon monoxide and hydrocarbons so that considerable expenditure in respect of equipment is at least necessary to achieve this, if at all.
It is accordingly an object of the present invention to provide a process for the oxidation of carbon monoxide and hydro- ~ -carbons with oxygen-containing gas to carbon dioxide and water in `
contact with a catalyst whose activity remains unaffected in contact -with gas mixtures, irrespective of the oxygen concentration therein, and which additionally has a low starting temperature.
To this end, the invention provides a process for the oxidation of carbon monoxide and hydrocarbons contained in exhaust gas of internal combustion engines with oxygen-containing gas to r - 3 -1065~23 carbon dioxide and water, which comprises carrying out the oxida~
tion at temperatures within the range 150 and 800C in contact with .
a carrier-supported catalyst, wherein alumina containing at most 0.2 weight % of alkali and converted to a mixture of ~-alumina and .:
a-alumina is the carrier and cerium in oxide form is the catalytically active ingredient, the catalytically active ingredient constituting 0.2 to 10 weight % of the carrier being deposited thereon.
Further preferred features of the present process pro-vide:
(a) for the oxidation to be carried out at temperatures within the range 200 and 700C; :
~b) for the oxidation to be carried out at temperatures within the range 300 and 600C;
(c) for the use of a catalyst wherein 0.5 to 8 weight %
of cerium in oxide form is deposited on the carrier;
~d) for the use of a catalyst produced by compressing an alumina selected from the group consisting of ~-alumina and boehmite into shapes; annealing the shapes for periods within the range 10 and 20 hours at temperatures within the range 1000 and 1250C;
impregnating the annealed shapes with an aqueous solution of a cerium salt of a readily decomposable acid; drying the cerium salt so ap-plied to the shapes at temperatures within the range 130 and 150C;
decomposing the dry cerium salt by gradually heating the shapes in a two-stage procedure to temperatures within the range 200 and 300C
and 450 and 550C, respectively; and annealing the resulting shapes containing cerium oxide at temperatures within the range 700 and 900C;
(e~ for the use of a catalyst produced by compressing the alumina carrier in admixture with graphite;
(f) for the use of a catalyst produced by compressing the alumina carrier in admixture with between 3 and 10 weight %, preferably 5 weight %, of graphite;
(g) for the use of a catalyst produced by burning off the graphite at temperatures within the range 550 and 750C, pre- ~
ferably 650C prior to annealing the shapes; and -~- -(h) for the use of a catalyst, wherein cerium nitrate is the cerium salt of a readily decomposable acid.
The process of the present invention, which is par-ticularly useful for the oxidation of carbon monoxide and hydro- ;
carbons with an excess of oxygen, ensures complete combustion of these substances.
Vital to the catalyst used in the present process is more particularly the alumina carrier, which is partially converted to -A1203. Carrier-supported catalysts having the catalytically active cerium oxide applied to incompletely dehydrated aluminum oxide monohydrate or to highly crystalline a-A1203 are considerably less active catalytically.
In addition to this, it is necessary for the alumina carrier to contain little alkali as alkalies are known to increase the starting temperature of carrier-supported catalysts.
The cerium salt used in aqueous solution for impregnat-ing the carrier and applying the catalytically active ingredient thereonto should have an anion which can be completely removed later, during calcination. The preferred cerium salt is cerium nitrate. Cerium sulfate produces catalysts of delayed activity.
The carrier should preferably be impregnated with a quantity of cerium salt solution which just corresponds to its volume of pores. In -other words, it is the concentration of the cerium salt solution used for impregnation and the volume of pores of the carrier which determine the cerium content of the resulting carrier-supported catalyst.
With respect to catalysts having a low starting temperature, it is ~
necessary for them to be made with the use of very pure cerium salt. So- `
called cerium mixed metal salts should conveniently not be used. -Qualitatively highly reliable carrier-supported catalysts for use ~.
in the present process are obtained in those cases in which the cerium salt applied to the carrier is dried over a prolonged period of time within the `
range 16 and 64 hours, for example.
The carrier-supported catalysts used in the ollowing Examples were cylindrical shapes 3 mm in diameter and 3 mm long. 17 normal liters (S.T.P.), per cc of catalyst per hour, of a test gas mixture was oxidized in contact therewith. The gas mixture contained 3 % by volume of 2~ 2 % by volume of cn, looo ppm of n-hexane, 2.5 % by volume of steam, the balance being N2, and was heated in each particular case to the testing temperature. The residual concentrations of C0 and n-hexane were identified in the oxidized gas and the conversion in % of these two substances was calculated therefrom.
The temperatures at which 50 and 90 %, respectively, of C0 and n-hexane, respectively, were found to have been converted to C02 and H20 (U50 G0; U90 C0; U50 Hex.; U90 Hex) were used as the activity indexes of the catalyst.
EXAMPLE 1: (Comparative Example~
Ce(N03)3 6 H20 was dried until the nitrate commenced decomposition and compressed into shapes. The shapes were heated for 10 hours to temp-eratures within the range 500 and 800C, with the supply of air. The catalytic activity was determined and the following results were obtained:
U50 C0 - 430C U50 Hex ~ 560C
UgO C0 - 540C UgO Hex - 660C
,, 106SlZ3 EXAMPLE 2: (Invention) ~-A1203 ~Aluminum oxide "C", a product o~ Degussa) ~as suspended in water and compacted therein. The resulting highly viscous magma was dried, admixed with
~065~23 ~ ~
These prior art catalysts are not fully satisfactory, however, as their activity varies depending on whether they are contacted with an oxidizing or reducing gas. More particularly, they are highly active if contacted with a mixture consisting of `
the gas to undergo oxidation and a stoichiometric or slightly understoichiometric proportion of oxygen, whilst they are less active if contacted with a mixture containing an excess of oxygen.
In other words, it is necessary for those prior art catalysts to be contacted with a gas mixture containing a stoi- `
chiometric proportion of oxygen, based on the carbon monoxide hydrocarbons present in the gas mixture to undergo oxidation. This is more especially necessary in an attempt (a) to maintain the cat-alyst active and (b) to ensure complete combustion of the gas to undergo oxidation. It should be borne in mind, however, that the exhaust gases of internal combustion engines always contain variable `
proportions of carbon monoxide and hydrocarbons so that considerable expenditure in respect of equipment is at least necessary to achieve this, if at all.
It is accordingly an object of the present invention to provide a process for the oxidation of carbon monoxide and hydro- ~ -carbons with oxygen-containing gas to carbon dioxide and water in `
contact with a catalyst whose activity remains unaffected in contact -with gas mixtures, irrespective of the oxygen concentration therein, and which additionally has a low starting temperature.
To this end, the invention provides a process for the oxidation of carbon monoxide and hydrocarbons contained in exhaust gas of internal combustion engines with oxygen-containing gas to r - 3 -1065~23 carbon dioxide and water, which comprises carrying out the oxida~
tion at temperatures within the range 150 and 800C in contact with .
a carrier-supported catalyst, wherein alumina containing at most 0.2 weight % of alkali and converted to a mixture of ~-alumina and .:
a-alumina is the carrier and cerium in oxide form is the catalytically active ingredient, the catalytically active ingredient constituting 0.2 to 10 weight % of the carrier being deposited thereon.
Further preferred features of the present process pro-vide:
(a) for the oxidation to be carried out at temperatures within the range 200 and 700C; :
~b) for the oxidation to be carried out at temperatures within the range 300 and 600C;
(c) for the use of a catalyst wherein 0.5 to 8 weight %
of cerium in oxide form is deposited on the carrier;
~d) for the use of a catalyst produced by compressing an alumina selected from the group consisting of ~-alumina and boehmite into shapes; annealing the shapes for periods within the range 10 and 20 hours at temperatures within the range 1000 and 1250C;
impregnating the annealed shapes with an aqueous solution of a cerium salt of a readily decomposable acid; drying the cerium salt so ap-plied to the shapes at temperatures within the range 130 and 150C;
decomposing the dry cerium salt by gradually heating the shapes in a two-stage procedure to temperatures within the range 200 and 300C
and 450 and 550C, respectively; and annealing the resulting shapes containing cerium oxide at temperatures within the range 700 and 900C;
(e~ for the use of a catalyst produced by compressing the alumina carrier in admixture with graphite;
(f) for the use of a catalyst produced by compressing the alumina carrier in admixture with between 3 and 10 weight %, preferably 5 weight %, of graphite;
(g) for the use of a catalyst produced by burning off the graphite at temperatures within the range 550 and 750C, pre- ~
ferably 650C prior to annealing the shapes; and -~- -(h) for the use of a catalyst, wherein cerium nitrate is the cerium salt of a readily decomposable acid.
The process of the present invention, which is par-ticularly useful for the oxidation of carbon monoxide and hydro- ;
carbons with an excess of oxygen, ensures complete combustion of these substances.
Vital to the catalyst used in the present process is more particularly the alumina carrier, which is partially converted to -A1203. Carrier-supported catalysts having the catalytically active cerium oxide applied to incompletely dehydrated aluminum oxide monohydrate or to highly crystalline a-A1203 are considerably less active catalytically.
In addition to this, it is necessary for the alumina carrier to contain little alkali as alkalies are known to increase the starting temperature of carrier-supported catalysts.
The cerium salt used in aqueous solution for impregnat-ing the carrier and applying the catalytically active ingredient thereonto should have an anion which can be completely removed later, during calcination. The preferred cerium salt is cerium nitrate. Cerium sulfate produces catalysts of delayed activity.
The carrier should preferably be impregnated with a quantity of cerium salt solution which just corresponds to its volume of pores. In -other words, it is the concentration of the cerium salt solution used for impregnation and the volume of pores of the carrier which determine the cerium content of the resulting carrier-supported catalyst.
With respect to catalysts having a low starting temperature, it is ~
necessary for them to be made with the use of very pure cerium salt. So- `
called cerium mixed metal salts should conveniently not be used. -Qualitatively highly reliable carrier-supported catalysts for use ~.
in the present process are obtained in those cases in which the cerium salt applied to the carrier is dried over a prolonged period of time within the `
range 16 and 64 hours, for example.
The carrier-supported catalysts used in the ollowing Examples were cylindrical shapes 3 mm in diameter and 3 mm long. 17 normal liters (S.T.P.), per cc of catalyst per hour, of a test gas mixture was oxidized in contact therewith. The gas mixture contained 3 % by volume of 2~ 2 % by volume of cn, looo ppm of n-hexane, 2.5 % by volume of steam, the balance being N2, and was heated in each particular case to the testing temperature. The residual concentrations of C0 and n-hexane were identified in the oxidized gas and the conversion in % of these two substances was calculated therefrom.
The temperatures at which 50 and 90 %, respectively, of C0 and n-hexane, respectively, were found to have been converted to C02 and H20 (U50 G0; U90 C0; U50 Hex.; U90 Hex) were used as the activity indexes of the catalyst.
EXAMPLE 1: (Comparative Example~
Ce(N03)3 6 H20 was dried until the nitrate commenced decomposition and compressed into shapes. The shapes were heated for 10 hours to temp-eratures within the range 500 and 800C, with the supply of air. The catalytic activity was determined and the following results were obtained:
U50 C0 - 430C U50 Hex ~ 560C
UgO C0 - 540C UgO Hex - 660C
,, 106SlZ3 EXAMPLE 2: (Invention) ~-A1203 ~Aluminum oxide "C", a product o~ Degussa) ~as suspended in water and compacted therein. The resulting highly viscous magma was dried, admixed with
3 weight ~ of graphite and ground. The ground material was compressed into shapes which were first heated to 650C to burn off the graphite and then annealed for 20 hours at 1100C. The carrier so made was impregnated with a cerlum tIII) nitrate solution and dried for 64 hours at 140& . To decompose the cerium nitrate, the carrier was first heated for 3 hours to 250C and then for 10 hours to 500C. The resulting cerium oxide-containing shapes -were finally annealed for 10 hours at 800C. Catalysts containing 2, 4 and 6 weight %, respectively, of cerium were made in this manner. Their activity `
was determined and the following results were obtained: -Ce-content in weight %
~ . . . s~ .
U50 C0 ~C] 190 170 160 ~;
.... __ UgO C0 ~C] 270 240 _ 205 _ U50 Hex ~C] 565 540 505 EXAMPLE 3: (Invention) ~-A1203 ~Aluminum oxide "C", a product of Degussa) was made into shapes in the manner described in Example 2. The graphite used as a compression aid was burnt o~f and shape specimens were annealed in each case for 20 hours at temperatures of 950C, 1000C, 1050C, lloo&, 1150C, 1200C, 1250C and 1300C, respectively. Following this, 6 weight % of cerium was applied to the individual specimens, in the manner described in Example 2. The activity of the resulting catalysts was determined and the following results were obtained:
Carrier annealed [ C ]
at C
50 CO 90 CO 50 Hex 90 Hex (gS0) 500 730 620 740 (1300) 270 390 600 730 : :
EXAMPLE 4: (Invention) Boehmite (AlOOH) containing 0.03 weight % of sodium was compressed into shapes in the manner described in Example 2. The graphite used as a compression aid was burnt off and shape specimens were annealed in each particular case for 20 hours at temperatures of 900C, 1000C, 1100CJ 1200C
and 1250C, respectively. Following this, 6 weight % of cerium was applied to the individual specimens, in the manner described in Example 2. The activity of the resulting catalysts was determined and the following results were obtained: :`
[ C 1 Carrier annealed at &
~ 900 _1000 _~_ 1100 _ 1200_ 1250 ._ . . __ . . . .__ ..
U50 Hex . 590 600 580 610 __ _600 . .
EXAMPLE 5: (Carrier containing alkali) The carrier-supported catalyst prepared in the manner described in Example 2 was impregnated with the quantity of potassium carbonate solution which was necessary to incorporate 0.5 weight % of K2C03 therein, then dried at 140C and annealed for 10 hours at 800C. The activity was determined and the following results were obtained:
U50 CO= 335C
-~O~;SlZ3 UgO CO ~ 450 C
U50 Hex = 620 C
EXAMPLE 6: (Carrier containing alkali) Bayerite ("Martifin" , a product of Martinswerk, Berheim) containing about 0.25 weight % of sodium (this is sodium originating from the particular process used for making the product) was compressed into shapes, in the manner described in Example 2. The graphite used as a compression aid was burnt off and shape specimens were annealed in each particular case for 20 hours at temperatures of 900C, 1000C, 1100C, 1200C and 1300C, respectively. ;-Following this, 6 weight % of cerium was applied to the individual carrier specimens, in the manner described in Example 2. The activity of the resulting catalysts was determined and the following results were obtained:
[ C ] Carrier annealed at C -.,,____ . .. :
. ' .
UgO C0 620 510 530 450 460 ... _._ . ,._,.. , _ ,_ . .
U50 Hex 590 570 610 600 610 EXAMPLE 7: (Less readiiy decomposable cerium salt) A catalyst containing 6 weight % of cerium was prepared in the manner described in Example 2 save that cerium sulfate was substitued for cerium nitrate. The activity of the catalyst so made was determined in a series of tests. Between the individual tests, the catalyst below the test gas mixture was annealed in each particular case for 10 minutes at 800 & .
Activity deter- U50 CO [ C ] U90 CO [ C ] U50 Hex [ C ]
mination 2 350 450 580 _ _ 240 340 530 _ * Trade mark _ g _ 1065~23 .:
EXAMPI.E 8: (Mixture of rare earths) _ Catalysts containing 6 weight % of rare earths were prepared in the manner described in Example 2 save t~at the cerium nitrate was replaced by salt solutions by dissolving cerium mixed metals of the following composition:
Alloy A: 56 % of Ce Alloy B: 49 % of Ce 28 % of La 23 % of La 10 % of Nd 15 % of Nd ~;
was determined and the following results were obtained: -Ce-content in weight %
~ . . . s~ .
U50 C0 ~C] 190 170 160 ~;
.... __ UgO C0 ~C] 270 240 _ 205 _ U50 Hex ~C] 565 540 505 EXAMPLE 3: (Invention) ~-A1203 ~Aluminum oxide "C", a product of Degussa) was made into shapes in the manner described in Example 2. The graphite used as a compression aid was burnt o~f and shape specimens were annealed in each case for 20 hours at temperatures of 950C, 1000C, 1050C, lloo&, 1150C, 1200C, 1250C and 1300C, respectively. Following this, 6 weight % of cerium was applied to the individual specimens, in the manner described in Example 2. The activity of the resulting catalysts was determined and the following results were obtained:
Carrier annealed [ C ]
at C
50 CO 90 CO 50 Hex 90 Hex (gS0) 500 730 620 740 (1300) 270 390 600 730 : :
EXAMPLE 4: (Invention) Boehmite (AlOOH) containing 0.03 weight % of sodium was compressed into shapes in the manner described in Example 2. The graphite used as a compression aid was burnt off and shape specimens were annealed in each particular case for 20 hours at temperatures of 900C, 1000C, 1100CJ 1200C
and 1250C, respectively. Following this, 6 weight % of cerium was applied to the individual specimens, in the manner described in Example 2. The activity of the resulting catalysts was determined and the following results were obtained: :`
[ C 1 Carrier annealed at &
~ 900 _1000 _~_ 1100 _ 1200_ 1250 ._ . . __ . . . .__ ..
U50 Hex . 590 600 580 610 __ _600 . .
EXAMPLE 5: (Carrier containing alkali) The carrier-supported catalyst prepared in the manner described in Example 2 was impregnated with the quantity of potassium carbonate solution which was necessary to incorporate 0.5 weight % of K2C03 therein, then dried at 140C and annealed for 10 hours at 800C. The activity was determined and the following results were obtained:
U50 CO= 335C
-~O~;SlZ3 UgO CO ~ 450 C
U50 Hex = 620 C
EXAMPLE 6: (Carrier containing alkali) Bayerite ("Martifin" , a product of Martinswerk, Berheim) containing about 0.25 weight % of sodium (this is sodium originating from the particular process used for making the product) was compressed into shapes, in the manner described in Example 2. The graphite used as a compression aid was burnt off and shape specimens were annealed in each particular case for 20 hours at temperatures of 900C, 1000C, 1100C, 1200C and 1300C, respectively. ;-Following this, 6 weight % of cerium was applied to the individual carrier specimens, in the manner described in Example 2. The activity of the resulting catalysts was determined and the following results were obtained:
[ C ] Carrier annealed at C -.,,____ . .. :
. ' .
UgO C0 620 510 530 450 460 ... _._ . ,._,.. , _ ,_ . .
U50 Hex 590 570 610 600 610 EXAMPLE 7: (Less readiiy decomposable cerium salt) A catalyst containing 6 weight % of cerium was prepared in the manner described in Example 2 save that cerium sulfate was substitued for cerium nitrate. The activity of the catalyst so made was determined in a series of tests. Between the individual tests, the catalyst below the test gas mixture was annealed in each particular case for 10 minutes at 800 & .
Activity deter- U50 CO [ C ] U90 CO [ C ] U50 Hex [ C ]
mination 2 350 450 580 _ _ 240 340 530 _ * Trade mark _ g _ 1065~23 .:
EXAMPI.E 8: (Mixture of rare earths) _ Catalysts containing 6 weight % of rare earths were prepared in the manner described in Example 2 save t~at the cerium nitrate was replaced by salt solutions by dissolving cerium mixed metals of the following composition:
Alloy A: 56 % of Ce Alloy B: 49 % of Ce 28 % of La 23 % of La 10 % of Nd 15 % of Nd ~;
4 % of Pr 12 % of Pr ~ Y
2 % of further r.e. 1 % of further r.e.
in nitric acid. The activity was determined and the following résults were obtained:
Cerium mixed metal alloy:
A B
, . .
U50 C0 ~~C ~ 280 330 UgO C0 [~C ] 380 430 U50 Hex [ C ] 550 525 EXAMPLE 9: ~Annealing period and temperature) The catalyst prepared in the manner described in Example 2 which had the following activity:
U50 CO = 160C
UgO C0 = 205C
U50 Hex = 505 C
was annealed for 13 hours at 1100C and then had the following activity:
UgO C0 = 280C
U50 Hex = 530 C
A catalyst was prepared in the manner described in Example 2, save that the annealing step at 700 - goo& was omitted and replaced by heat treatment at 300 - 400C after decomposition of the cerium salt.
The catalyst so made had the following activity:
1065~23 U50 C0 ~ 185 C
UgO C0 - 355C
U50 Hex = 535 C
eXAMPL~ 10:
Basic aluminum chloride A12(0H)5CL . 3 H20 ("Locron" , a product of Farbwerke Hoechst AG) was dissolved in water and the solution was admixed with the quantity of cerium nitrate necessary to obtain a catalyst containing 6 % of cerium. The whole was admixed with ammonia to jointly precipitate the ~;
Al and Ce hydroxides. The precipitate was filtered off, scrubbed with water and dried. After the addition of 5 weight % of graphite, the dry precipitate :
was compressed into shapes. The graphite was burnt off at 650C and the ~ -;
shapes were annealed for 20 hours at 800C. The activity was determined and the following results were obtained:
Ugo CO ' 450C
U50 Hex = 540C
UgO Hex ~ 640C-.
* Trade mark
2 % of further r.e. 1 % of further r.e.
in nitric acid. The activity was determined and the following résults were obtained:
Cerium mixed metal alloy:
A B
, . .
U50 C0 ~~C ~ 280 330 UgO C0 [~C ] 380 430 U50 Hex [ C ] 550 525 EXAMPLE 9: ~Annealing period and temperature) The catalyst prepared in the manner described in Example 2 which had the following activity:
U50 CO = 160C
UgO C0 = 205C
U50 Hex = 505 C
was annealed for 13 hours at 1100C and then had the following activity:
UgO C0 = 280C
U50 Hex = 530 C
A catalyst was prepared in the manner described in Example 2, save that the annealing step at 700 - goo& was omitted and replaced by heat treatment at 300 - 400C after decomposition of the cerium salt.
The catalyst so made had the following activity:
1065~23 U50 C0 ~ 185 C
UgO C0 - 355C
U50 Hex = 535 C
eXAMPL~ 10:
Basic aluminum chloride A12(0H)5CL . 3 H20 ("Locron" , a product of Farbwerke Hoechst AG) was dissolved in water and the solution was admixed with the quantity of cerium nitrate necessary to obtain a catalyst containing 6 % of cerium. The whole was admixed with ammonia to jointly precipitate the ~;
Al and Ce hydroxides. The precipitate was filtered off, scrubbed with water and dried. After the addition of 5 weight % of graphite, the dry precipitate :
was compressed into shapes. The graphite was burnt off at 650C and the ~ -;
shapes were annealed for 20 hours at 800C. The activity was determined and the following results were obtained:
Ugo CO ' 450C
U50 Hex = 540C
UgO Hex ~ 640C-.
* Trade mark
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the oxidation of carbon monoxide and hydrocarbons contained in exhaust gas of internal combustion engines with oxygen-containing gas to carbon dioxide and water, which comprises carrying out the oxidation at temperatures within the range 150 and 800°C in contact with a carrier-supported catalyst, wherein alumina containing at most 0.2 weight % of alkali and converted to a mixture of .delta.-alumina and .alpha.-alumina is the carrier and cerium in oxide form is the catalytically active ingredient, the catalytically active in-gredient constituting 0.2 to 10 weight % of the carrier being deposited there-on.
2. The process as claimed in claim 1, wherein the oxidation is carried out at temperatures within the range 200 and 700°C.
3. The process as claimed in claim 1, wherein the oxidation is carried out at temperatures within the range 300 and 600°C.
4. The process as claimed in claim 1, wherein the oxidation is carried out in contact with a carrier-supported catalyst having from 0,5 to 8 weight % of cerium in oxide form deposited on the carrier.
5. The process as claimed in claim 1, wherein the oxidation is carried out in contact with a carrier-supported catalyst produced by compressing an alumina selected from the group consisting of .delta.-alumina and boehmite into shapes; annealing the shapes for periods within the range 10 to 20 hours at temperatures within the range 1000 and 1250°C; impregnating the annealed shapes with an aqueous solution of a cerium salt of a readily decomposable acid; drying the cerium salt so applied to the shapes at temperatures within the range 130 and 150°C; decomposing the dry cerium salt by gradually heating the shapes in a two-stage procedure to temperatures within the range 200 to 300°C and 450 and 550°C, respectively; and annealing the resulting shapes containing cerium oxide at temperatures within the range 700 and 900°C.
6. The process as claimed in claim 5, wherein the oxidation is carried out in contact with a catalyst produced by compressing the alumina in admixture with graphite.
7. The process as claimed in claim 6, wherein the oxidation is carried out in contact with a carrier-supported catalyst produced by compress-ing the alumina in admixture with between 3 and 10 weight % of graphite.
8. The process as claimed in claim 6, wherein the oxidation is carried out in contact with a carrier-supported catalyst produced by burning off the graphite at temperatures within the range 550 to 750°C prior to annealing the shapes.
9. The process as claimed in claim 5, wherein the oxidation is carried out in contact with a carrier-supported catalyst produced by using cerium nitrate as the cerium salt of a readily decomposable acid.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2412176A DE2412176A1 (en) | 1974-03-14 | 1974-03-14 | PROCESS FOR OXIDIZATION OF CARBON MONOXIDE AND HYDROCARBONS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1065123A true CA1065123A (en) | 1979-10-30 |
Family
ID=5910009
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA222,637A Expired CA1065123A (en) | 1974-03-14 | 1975-03-20 | Process for the oxidation of carbon monoxide and hydrocarbons |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS50125966A (en) |
| BE (1) | BE826577A (en) |
| CA (1) | CA1065123A (en) |
| CH (1) | CH611974A5 (en) |
| CS (1) | CS188222B2 (en) |
| DD (1) | DD117431A5 (en) |
| DE (1) | DE2412176A1 (en) |
| DK (1) | DK103175A (en) |
| ES (1) | ES435550A1 (en) |
| FR (1) | FR2264180B1 (en) |
| GB (1) | GB1477423A (en) |
| IL (1) | IL46724A (en) |
| IT (1) | IT1032280B (en) |
| SE (1) | SE7502827L (en) |
| ZA (1) | ZA751142B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4087897B2 (en) * | 1991-11-26 | 2008-05-21 | バスフ・カタリスツ・エルエルシー | Improved oxidation catalyst and method of use |
| US5580535A (en) * | 1994-07-07 | 1996-12-03 | Engelhard Corporation | System and method for abatement of food cooking fumes |
| DE102013221423A1 (en) * | 2013-10-22 | 2015-04-23 | Umicore Ag & Co. Kg | Catalyst for the oxidation of CO and HC at low temperatures |
-
1974
- 1974-03-14 DE DE2412176A patent/DE2412176A1/en not_active Withdrawn
-
1975
- 1975-02-25 ZA ZA00751142A patent/ZA751142B/en unknown
- 1975-02-27 GB GB825875A patent/GB1477423A/en not_active Expired
- 1975-02-28 IL IL46724A patent/IL46724A/en unknown
- 1975-03-06 JP JP50027578A patent/JPS50125966A/ja active Pending
- 1975-03-12 IT IT48563/75A patent/IT1032280B/en active
- 1975-03-12 BE BE154244A patent/BE826577A/en unknown
- 1975-03-12 ES ES435550A patent/ES435550A1/en not_active Expired
- 1975-03-12 DD DD184729A patent/DD117431A5/xx unknown
- 1975-03-13 CS CS751698A patent/CS188222B2/en unknown
- 1975-03-13 DK DK103175A patent/DK103175A/da unknown
- 1975-03-13 SE SE7502827A patent/SE7502827L/en unknown
- 1975-03-14 FR FR7508132A patent/FR2264180B1/fr not_active Expired
- 1975-03-14 CH CH331775A patent/CH611974A5/en not_active IP Right Cessation
- 1975-03-20 CA CA222,637A patent/CA1065123A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ZA751142B (en) | 1976-01-28 |
| DK103175A (en) | 1975-09-15 |
| DD117431A5 (en) | 1976-01-12 |
| SE7502827L (en) | 1975-09-15 |
| IL46724A0 (en) | 1975-04-25 |
| CH611974A5 (en) | 1979-06-29 |
| IT1032280B (en) | 1979-05-30 |
| GB1477423A (en) | 1977-06-22 |
| FR2264180B1 (en) | 1980-08-14 |
| DE2412176A1 (en) | 1975-10-16 |
| CS188222B2 (en) | 1979-02-28 |
| JPS50125966A (en) | 1975-10-03 |
| BE826577A (en) | 1975-09-12 |
| ES435550A1 (en) | 1976-12-16 |
| FR2264180A1 (en) | 1975-10-10 |
| IL46724A (en) | 1978-03-10 |
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