CA2353759A1 - Oxidizing catalysts, carbon monoxide sensor, and hydrogen sensor - Google Patents
Oxidizing catalysts, carbon monoxide sensor, and hydrogen sensor Download PDFInfo
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- CA2353759A1 CA2353759A1 CA002353759A CA2353759A CA2353759A1 CA 2353759 A1 CA2353759 A1 CA 2353759A1 CA 002353759 A CA002353759 A CA 002353759A CA 2353759 A CA2353759 A CA 2353759A CA 2353759 A1 CA2353759 A1 CA 2353759A1
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- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
- C01B3/56—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
- C01B3/58—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids including a catalytic reaction
- C01B3/583—Separation 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
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- G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
- G01N27/16—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas
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- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/0435—Catalytic purification
- C01B2203/044—Selective oxidation of carbon monoxide
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- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/0465—Composition of the impurity
- C01B2203/047—Composition of the impurity the impurity being carbon monoxide
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Abstract
The present invention provides a catalyst selectively oxidizing carbon monoxide in a mixed gas comprising carbon monoxide and hydrogen as well as a catalyst selectively oxi-dizing hydrogen. A catalyst selectively oxidizing carbon monoxide is obtained by dispersing platinum black on a surface of a base metal compound oxide including Co2o3, MnO2, CuO, and Cr2O3, and forming an Ag2O layer on the platinum black layer. The catalyst selectively oxidizing hydrogen in a mixed gas comprising carbon monoxide and hydrogen is obtained by dispersing Ag2O on a surface of said base metal compound oxide and further forming a platinum black layer on the Ag2O layer. In addition the present invention provides a contact combustion carbon monoxide sensor not having the sensitivity to hydrogen as well as that not having the sensitivity to carbon monoxide.
Description
OXIDIZING CATALYSTS, CARBON MONOXIDE SENSOR, AND HYDROGEN
SENSOR
FIELD OF THE INVENTION
This invention relates to oxidizing catalysts, a carbon monoxide sensor, and a hydrogen sensor using the catalyst respectively, and more specifically t.o a catalyst selective-ly oxidizing carbon monoxide, a catalyst selectively oxidiz-1D ing hydrogen, an carbon monoxide sensor not having the sensitivity to hydrogen existing together with the carbon monoxide, a hydrogen sensor not having the sensitivity to carbon monoxide existing together with the hydrogen, and a hydrogen purification catalyst for a fuel cell.
CONVENTIONAL TECHNOLOGY
Carbon monoxide (CO) and hydrogen (H2) coexist in exhaust gases generated when a coal gas, an water gas, a city gas, an LPG and other types of gases are incompletely 2D combusted. As the carbon monoxide contained in the exhaust gases as described above is highly toxic, the following practice is applied for inspection of gas incomplete combus-tion alarm units in Japan.
In the practice for inspection of a city gas incomplete combustion alarm unit, it is required that the alarm unit can correctly give an alarm when carbon monoxide is present at 200 ppm, and also that the alarm unit should not give a false alarm when hydrogen is present: at 500 ppm and ethyl alcohol at 1,000 ppm. In the practice for inspection of a 3D high pressure gas incomplete combustion gas alarm unit, it is required that the alarm unit can dive a first alarm when carbon monoxide is present at 250 ppm and hydrogen at 125 ppm and also can give a second alarm when carbon monoxide is present at 550 ppm and hydrogen at 275 ppm, and further that the alarm should not give a false alarm when ethyl alcohol is present at 1,000 ppm.
However, the prior sensors can n.ot cause an alarm unit l to give an alarm by selectively sensing carbon monoxide or hydrogen existing at the low concf~ntration. A tin (II) oxide (Sn02) semiconductor sensor is excellent in its sen-sitivity at the low concentration, but the sensor can not sense any gas selectively at all, and even if the sensor is temporally corrected with an activated carbon filter or the like, its repeatability is lost dues to degradation of the activated carbon, and the sensor becomes unavailable. The contact combustion sensor detects temperature increase caused when a combustible gas reacts with a catalyst and burns on a heated coil as a change in the electric resist ance, and there is not carbon monoxide sensor not having the sensitivity to hydrogen even among those in which the sen sitivity to a gas (output) is proportional to the gas con centration.
It has generally been recognized that the hopcalite catalyst comprising Mn02 by 70~ and Cu03 by 30~, or Mn02 by 50~, Cu0 by 30~, Co203 by 15~ and Ag~,O by 5~ is promising as a catalyst capable of selectively oxidizing and detecting carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen. As a carbon monoxide sensor, however, it has low selectivity to the gas with poor sensitivity, and fur-ther the catalyst is easily affected by poisoning and humid-ity and the performance substantially changes as time pass-es, so that the catalyst can not actually be used for any industrial purposes.
In the fixed high molecular types of fuel cell used in a fuel cell car now under development as an environment-compatible car, hydrogen is used as the fuel. As a method for production of hydrogen as the fuel, the hydrogen absorb-ing alloys method, catalytic decomposition of gasoline, methyl alcohol catalytic decomposition method, or other methods have been used. Of these methods, the hydrogen absorbing alloys method has the defect that the alloy used in the method being a rare earth alloy such as La-Ni5 is expensive and heavy, and that the alloy is depleted.
Although high purity hydrogen can be obtained by this meth-
SENSOR
FIELD OF THE INVENTION
This invention relates to oxidizing catalysts, a carbon monoxide sensor, and a hydrogen sensor using the catalyst respectively, and more specifically t.o a catalyst selective-ly oxidizing carbon monoxide, a catalyst selectively oxidiz-1D ing hydrogen, an carbon monoxide sensor not having the sensitivity to hydrogen existing together with the carbon monoxide, a hydrogen sensor not having the sensitivity to carbon monoxide existing together with the hydrogen, and a hydrogen purification catalyst for a fuel cell.
CONVENTIONAL TECHNOLOGY
Carbon monoxide (CO) and hydrogen (H2) coexist in exhaust gases generated when a coal gas, an water gas, a city gas, an LPG and other types of gases are incompletely 2D combusted. As the carbon monoxide contained in the exhaust gases as described above is highly toxic, the following practice is applied for inspection of gas incomplete combus-tion alarm units in Japan.
In the practice for inspection of a city gas incomplete combustion alarm unit, it is required that the alarm unit can correctly give an alarm when carbon monoxide is present at 200 ppm, and also that the alarm unit should not give a false alarm when hydrogen is present: at 500 ppm and ethyl alcohol at 1,000 ppm. In the practice for inspection of a 3D high pressure gas incomplete combustion gas alarm unit, it is required that the alarm unit can dive a first alarm when carbon monoxide is present at 250 ppm and hydrogen at 125 ppm and also can give a second alarm when carbon monoxide is present at 550 ppm and hydrogen at 275 ppm, and further that the alarm should not give a false alarm when ethyl alcohol is present at 1,000 ppm.
However, the prior sensors can n.ot cause an alarm unit l to give an alarm by selectively sensing carbon monoxide or hydrogen existing at the low concf~ntration. A tin (II) oxide (Sn02) semiconductor sensor is excellent in its sen-sitivity at the low concentration, but the sensor can not sense any gas selectively at all, and even if the sensor is temporally corrected with an activated carbon filter or the like, its repeatability is lost dues to degradation of the activated carbon, and the sensor becomes unavailable. The contact combustion sensor detects temperature increase caused when a combustible gas reacts with a catalyst and burns on a heated coil as a change in the electric resist ance, and there is not carbon monoxide sensor not having the sensitivity to hydrogen even among those in which the sen sitivity to a gas (output) is proportional to the gas con centration.
It has generally been recognized that the hopcalite catalyst comprising Mn02 by 70~ and Cu03 by 30~, or Mn02 by 50~, Cu0 by 30~, Co203 by 15~ and Ag~,O by 5~ is promising as a catalyst capable of selectively oxidizing and detecting carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen. As a carbon monoxide sensor, however, it has low selectivity to the gas with poor sensitivity, and fur-ther the catalyst is easily affected by poisoning and humid-ity and the performance substantially changes as time pass-es, so that the catalyst can not actually be used for any industrial purposes.
In the fixed high molecular types of fuel cell used in a fuel cell car now under development as an environment-compatible car, hydrogen is used as the fuel. As a method for production of hydrogen as the fuel, the hydrogen absorb-ing alloys method, catalytic decomposition of gasoline, methyl alcohol catalytic decomposition method, or other methods have been used. Of these methods, the hydrogen absorbing alloys method has the defect that the alloy used in the method being a rare earth alloy such as La-Ni5 is expensive and heavy, and that the alloy is depleted.
Although high purity hydrogen can be obtained by this meth-
2 od, the price of the hydrogen fuel is expensive. In the catalytic decomposition of gasoline, as the ratio of carbon atoms to hydrogen atoms contained in gasoline is higher in comparison to that in methanol, the method has the defect that a large quantity of hydrogen can not be produced. What is most expected among the methods listed above is the method of catalytically decomposing methanol allowing easy treatment of reactants in which methanol can be decomposed with a catalyst at a low temperature. Unless carbon monox-ide contained in the hydrogen gas obtained through catalytic decomposition of methanol is removed,, electrodes of the fuel cell are chemically degraded with the life becoming shorter, and there has been the defect in the prior art that carbon monoxide can not efficiently be removed from a gas mixture comprising carbon monoxide and hydrogen.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a catalyst capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen as well as a catalyst capable of select5.vely oxidizing hydrogen in the gas mixture. It is another object of the present invention to provide contact combustion carbon monoxide sensor not having the sensitivity to hydrogen as well as a contact combustion hydrogen sensor not having the sensitiv-ity to carbon monoxide.
The present invention provides a catalyst obtained by dispersing platinum black over a surface of a base metal compound oxide containing Co203, Mr~02, CuO, and Cr203 to form an Ag20 layer on the platinum black layer and charac-terized in that the catalyst is capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen. In addition,, the present invention provides a catalyst obtained by dispersing Ag20 over a surface of the base metal compound oxide to form a platinum black layer on the Ag20 layer and characterized in that the catalyst is capable of selecting oxidizing hydrogen in a gas
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a catalyst capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen as well as a catalyst capable of select5.vely oxidizing hydrogen in the gas mixture. It is another object of the present invention to provide contact combustion carbon monoxide sensor not having the sensitivity to hydrogen as well as a contact combustion hydrogen sensor not having the sensitiv-ity to carbon monoxide.
The present invention provides a catalyst obtained by dispersing platinum black over a surface of a base metal compound oxide containing Co203, Mr~02, CuO, and Cr203 to form an Ag20 layer on the platinum black layer and charac-terized in that the catalyst is capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen. In addition,, the present invention provides a catalyst obtained by dispersing Ag20 over a surface of the base metal compound oxide to form a platinum black layer on the Ag20 layer and characterized in that the catalyst is capable of selecting oxidizing hydrogen in a gas
3 mixture comprising carbon monoxide and hydrogen. Further the present invention provides a contact combustion carbon monoxide sensor using the catalyst selectively oxidizing carbon monoxide in its active section as well as a contact combustion hydrogen sensor using the catalyst selectively oxidizing hydrogen in the active section.
DETAILED DESCRIPTION OF THE INVENTION
In this invention, a base metal compound oxide contain ing Co203, Mn02, CuO, and Cr203 each generating a small heat of oxide formation (- D Ho) functions as a source to AG2o, and activates the Ag catalyst. There is no specific limitation aver composition of the base metal, but it is preferable that the content of Mn02 is in the range from 44 to 55 weight ~, 2Cu0-Cr203 in the range from 25 to 40 weight and Co203 in the range from 15 to 20 weight ~.
A catalyst capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen was obtained by dispersing platinum black parti-cles over a surface of the base metal. compound oxide to form an Ag2o layer on the surface. Also a catalyst capable of selectively oxidizing hydrogen in the gas mixture above was obtained by dispersing Ag20 over a surface of the base metal compound oxide to form a platinum black layer on the sur-face. These catalysts could repeatedly be used, and were stable in use for a long time.
The catalyst produced by homogeneously milling the base metal compound oxide, molding, activation, and then dis-persing platinum black particles on. a surface and forming an Ag20 layer on platinum black is capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen. The catalyst is more stable as compared to the hopcalite. When the catalyst selectively oxidizing only carbon monoxide is used as a fuel cell, the catalyst oxidizes only carbon monoxide contained in the hydrogen gas of the fuel obtained by decomposing methanol with a catalyst such as Zn0-Cr203 or the like to carbon
DETAILED DESCRIPTION OF THE INVENTION
In this invention, a base metal compound oxide contain ing Co203, Mn02, CuO, and Cr203 each generating a small heat of oxide formation (- D Ho) functions as a source to AG2o, and activates the Ag catalyst. There is no specific limitation aver composition of the base metal, but it is preferable that the content of Mn02 is in the range from 44 to 55 weight ~, 2Cu0-Cr203 in the range from 25 to 40 weight and Co203 in the range from 15 to 20 weight ~.
A catalyst capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen was obtained by dispersing platinum black parti-cles over a surface of the base metal. compound oxide to form an Ag2o layer on the surface. Also a catalyst capable of selectively oxidizing hydrogen in the gas mixture above was obtained by dispersing Ag20 over a surface of the base metal compound oxide to form a platinum black layer on the sur-face. These catalysts could repeatedly be used, and were stable in use for a long time.
The catalyst produced by homogeneously milling the base metal compound oxide, molding, activation, and then dis-persing platinum black particles on. a surface and forming an Ag20 layer on platinum black is capable of selectively oxidizing carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen. The catalyst is more stable as compared to the hopcalite. When the catalyst selectively oxidizing only carbon monoxide is used as a fuel cell, the catalyst oxidizes only carbon monoxide contained in the hydrogen gas of the fuel obtained by decomposing methanol with a catalyst such as Zn0-Cr203 or the like to carbon
4 dioxide, and the resultant gas mixture does not give any damage to electrodes of the fixed high molecular type of fuel cell used for vehicles with a long life of the fuel cell insured.
The catalyst selectively oxidizing carbon monoxide according to the present invention is used in an active sec-tion of a carbon monoxide sensor based on the contact com-bustion system to form a sensor which can selectively detect carbon monoxide. A catalyst was obtained by dispersing platinum black particles on a surface formed by electrodepo-siting an electrodeposition coating containing the base metal compound oxide by 60 to 70 weight ~ and Y-A1203 by 30 to 40 weight ~ on a Pt line coil. or an Fe-Pd line coil and calcinating the electrodeposited coating to form an Ag20 layer thereon. The contact combustion carbon monoxide sensor having a bridge circuit in which a coil having this catalyst is used in the active section is a contact combus-tion carbon monoxide sensor providing output for carbon monoxide in the range from 20 to 22 mV when the carbon monoxide concentration is at 500 ppm or output for hydrogen in the range from 0 to 1 mV when the hydrogen concentration is at 500 ppm. This carbon monoxide sensor is that not having the sensitivity to hydrogen even when carbon monoxide and hydrogen coexist. The carbon monoxide sensor having the sensitivity only to carbon monoxide can be used in applica-tions such as city gas incomplete combustion alarm units, alarm units based on practices in foreign countries, and other security-related devices.
The hydrogen sensor according to the present invention 3~ is a contact combustion hydrogen sensor having a bridge circuit in which a coil having a catalyst formed by dispers ing Ag20 over a surface formed by electrically depositing an electrodeposition coating comprising the base metal compound oxide by 60 to 70 weight ~ and Y-A1203 by 30 to 40 weight on a Pt or Fe-Pd line coil and then calcinating the compound oxide is used, and have the sensitivity (output) of 0 to 1 mV for carbon monoxide at the concentration of 500 ppm and
The catalyst selectively oxidizing carbon monoxide according to the present invention is used in an active sec-tion of a carbon monoxide sensor based on the contact com-bustion system to form a sensor which can selectively detect carbon monoxide. A catalyst was obtained by dispersing platinum black particles on a surface formed by electrodepo-siting an electrodeposition coating containing the base metal compound oxide by 60 to 70 weight ~ and Y-A1203 by 30 to 40 weight ~ on a Pt line coil. or an Fe-Pd line coil and calcinating the electrodeposited coating to form an Ag20 layer thereon. The contact combustion carbon monoxide sensor having a bridge circuit in which a coil having this catalyst is used in the active section is a contact combus-tion carbon monoxide sensor providing output for carbon monoxide in the range from 20 to 22 mV when the carbon monoxide concentration is at 500 ppm or output for hydrogen in the range from 0 to 1 mV when the hydrogen concentration is at 500 ppm. This carbon monoxide sensor is that not having the sensitivity to hydrogen even when carbon monoxide and hydrogen coexist. The carbon monoxide sensor having the sensitivity only to carbon monoxide can be used in applica-tions such as city gas incomplete combustion alarm units, alarm units based on practices in foreign countries, and other security-related devices.
The hydrogen sensor according to the present invention 3~ is a contact combustion hydrogen sensor having a bridge circuit in which a coil having a catalyst formed by dispers ing Ag20 over a surface formed by electrically depositing an electrodeposition coating comprising the base metal compound oxide by 60 to 70 weight ~ and Y-A1203 by 30 to 40 weight on a Pt or Fe-Pd line coil and then calcinating the compound oxide is used, and have the sensitivity (output) of 0 to 1 mV for carbon monoxide at the concentration of 500 ppm and
5 also of 35 to 40 mV for hydrogen at the concentration of 500 ppm. This hydrogen sensor does not show its sensitivity to carbon monoxide even when carbon monoxide and hydrogen coexist. This hydrogen sensor can detect hydrogen generated when the trans-oil is degraded.
With the catalyst selectively o;~idizing carbon monoxide and that selectively oxidizing hydrogen each according to the present invention, it is possible to selectively detect and oxidize carbon monoxide or hydrogen at the low concen-tration, and the catalysts are extremely useful for provid-ing a carbon monoxide sensor not having the sensitivity to hydrogen which has been a defect of carbon monoxide sensors based on the conventional technology as well as for reform-ing hydrogen for a fuel cell.
The present invention is described in detail below with reference to the embodiments. The ernbodiments are described below only for the illustrative-purpose, and are not intend-ed to limit the present invention in any means.
Example 1 Mn02 52 weight $
2Cu0-Cr203 32 weight ~
Co203 16 weight ~
A-mixture of the compounds above was mixed and pul-verized with a ball mill and was then molded into a cylin-drical body with the diameter of 3.0 mm and length of 3 mm, which was calcinated under the temperature of 500 °C to activate the mixture as an oxide catalyst. After the sur-face was fully cleaned, the [Pt(NH3)4](N03)2(1:60) solution was applied to the surface by dipping or blowing, the sur-face was dried and subjected to thermal decomposition to obtain platinum black, and then the AgN03 0.7 g/L solution was applied to the surface by spraying or the like, which was dried, subjected to thermal decomposition, washed with water, and dried to obtain a catalyat. 20 L of mixed gas comprising carbon monoxide at the 500 ppm and hydrogen at 500 ppm was passed through a vessel filled with this cata-
With the catalyst selectively o;~idizing carbon monoxide and that selectively oxidizing hydrogen each according to the present invention, it is possible to selectively detect and oxidize carbon monoxide or hydrogen at the low concen-tration, and the catalysts are extremely useful for provid-ing a carbon monoxide sensor not having the sensitivity to hydrogen which has been a defect of carbon monoxide sensors based on the conventional technology as well as for reform-ing hydrogen for a fuel cell.
The present invention is described in detail below with reference to the embodiments. The ernbodiments are described below only for the illustrative-purpose, and are not intend-ed to limit the present invention in any means.
Example 1 Mn02 52 weight $
2Cu0-Cr203 32 weight ~
Co203 16 weight ~
A-mixture of the compounds above was mixed and pul-verized with a ball mill and was then molded into a cylin-drical body with the diameter of 3.0 mm and length of 3 mm, which was calcinated under the temperature of 500 °C to activate the mixture as an oxide catalyst. After the sur-face was fully cleaned, the [Pt(NH3)4](N03)2(1:60) solution was applied to the surface by dipping or blowing, the sur-face was dried and subjected to thermal decomposition to obtain platinum black, and then the AgN03 0.7 g/L solution was applied to the surface by spraying or the like, which was dried, subjected to thermal decomposition, washed with water, and dried to obtain a catalyat. 20 L of mixed gas comprising carbon monoxide at the 500 ppm and hydrogen at 500 ppm was passed through a vessel filled with this cata-
6 lyst and having the diameter of 1 cm and length of 31 cm at the flow rate of 22.5 L/min, and no carbon monoxide was detected from the exhausted gas, and a gas mixture compris ing carbon dioxide at the concentration of 500 ppm and hydrogen at the concentration of 500 ppm was obtained.
Example 2 Mn02 30 weight ~
2Cu0-Cr203 18 weight ~
Co203 9 weight ~
y-A1203 43 weight ~
An electrodeposition coating containing the base metal oxide and y-A1203 as described above was electrically deposited on a coil formed by coiling an Fe-Pd line with the diameter of 30 ~zm and having 22 turns each with the inner diameter in the range from 0.8 to 1.0 mm. The compound oxide was formed at the rate of about 0.02 g per coil.
After died under a low temperature, the coil was dried for two hours under the temperature of 120 °C, and then was calcinated for 15 to 20 minutes under the temperature of 500 °C to obtain a compound oxide. About 0.1 cc of the [Pt(NH3)4](N03)2(1:60) solution was applied to a surface of the compound oxide, which was dried and decomposed under the temperature of 500 °C to give platinum black. The surface was cleaned and dried, and then about 0.1 cc of the AgN03 0.7 g/L solution was applied to the platinum black with the surface dried, subjected to thermal decomposition, and washed, and the coil having the resu:Ltant catalyst was used in an active section of a bridge circuit of the contact combustion carbon monoxide sensor. when this sensor was used as a 6V sensor based on the contact combustion system under the conditions of sensor temperature in the range from 150 to 160 °C and bridge voltage of 6V for D.C 25 mA, the sensor provided the output of 20 to :?2 mV for carbon monox-ide at the concentration of 500 ppm, but it provided only the output of 0 to 2 mV for hydrogen at the concentration of 500 ppm.
Example 2 Mn02 30 weight ~
2Cu0-Cr203 18 weight ~
Co203 9 weight ~
y-A1203 43 weight ~
An electrodeposition coating containing the base metal oxide and y-A1203 as described above was electrically deposited on a coil formed by coiling an Fe-Pd line with the diameter of 30 ~zm and having 22 turns each with the inner diameter in the range from 0.8 to 1.0 mm. The compound oxide was formed at the rate of about 0.02 g per coil.
After died under a low temperature, the coil was dried for two hours under the temperature of 120 °C, and then was calcinated for 15 to 20 minutes under the temperature of 500 °C to obtain a compound oxide. About 0.1 cc of the [Pt(NH3)4](N03)2(1:60) solution was applied to a surface of the compound oxide, which was dried and decomposed under the temperature of 500 °C to give platinum black. The surface was cleaned and dried, and then about 0.1 cc of the AgN03 0.7 g/L solution was applied to the platinum black with the surface dried, subjected to thermal decomposition, and washed, and the coil having the resu:Ltant catalyst was used in an active section of a bridge circuit of the contact combustion carbon monoxide sensor. when this sensor was used as a 6V sensor based on the contact combustion system under the conditions of sensor temperature in the range from 150 to 160 °C and bridge voltage of 6V for D.C 25 mA, the sensor provided the output of 20 to :?2 mV for carbon monox-ide at the concentration of 500 ppm, but it provided only the output of 0 to 2 mV for hydrogen at the concentration of 500 ppm.
7 Example 3 Mn02 29 weight ~
Cu0 17 weight ~
Co203 11 weight ~
Y-A1203 43 weight ~
The electrodeposition coating containing the base metal oxide and y-A1203 as described above was adjusted and was electrically deposited on a Fe-Pd 30 lzm line coil. More specifically, the coating was electrically deposited on a coil formed by coiling the Fe-Pd line with the diameter of 30 um with 22 turns each having they inner diameter in the range from 0.8 to 1.0 mm so that a cfuantity of the compound oxide was about 0.02 g for each coil. After dried under a low temperature, further the coil was dried for two hours under the temperature of 120 °C and calcinated for 15 to 20 minutes under the temperature of 500 °C to obtain an com-pound oxide. After about 0.1 cc of the AgN03 0.7 g/L was applied to a surface of the compound oxide and was dried, the [Pt(NH3)4](N03)2(1:60) solution was adjusted, and about p , 1 cc of the solution was applied to a surface of the compound oxide, the surface was died and subjected to decom-position under the temperature of 500 °C to form platinum black, and a coil having the resultant catalyst was used in an active section of a bridge circuit of a hydrogen sensor based on the contact combustion system. When this sensor was used as a 6 V sensor based on the contact combustion system under the conditions of senior temperature in the range from 150 to 160 °C, D.C voltage of 6 V and 25 mA, the sensor provided the output of about 0 mV for carbon monoxide at the concentration of 500 ppm, .and also provided the output of 35 to 40 mV for hydrogen at the concentration of 500 ppm. When only the active section was subjected to the aging test by applying the voltage of 3.5 V for 99 days thereto, the average value of the sensitivity to hydrogen (output) at the concentration of 500 ppm was 32.5 mV, and that to carbon monoxide at the concentration of 500 ppm was 0.1 mV.
Cu0 17 weight ~
Co203 11 weight ~
Y-A1203 43 weight ~
The electrodeposition coating containing the base metal oxide and y-A1203 as described above was adjusted and was electrically deposited on a Fe-Pd 30 lzm line coil. More specifically, the coating was electrically deposited on a coil formed by coiling the Fe-Pd line with the diameter of 30 um with 22 turns each having they inner diameter in the range from 0.8 to 1.0 mm so that a cfuantity of the compound oxide was about 0.02 g for each coil. After dried under a low temperature, further the coil was dried for two hours under the temperature of 120 °C and calcinated for 15 to 20 minutes under the temperature of 500 °C to obtain an com-pound oxide. After about 0.1 cc of the AgN03 0.7 g/L was applied to a surface of the compound oxide and was dried, the [Pt(NH3)4](N03)2(1:60) solution was adjusted, and about p , 1 cc of the solution was applied to a surface of the compound oxide, the surface was died and subjected to decom-position under the temperature of 500 °C to form platinum black, and a coil having the resultant catalyst was used in an active section of a bridge circuit of a hydrogen sensor based on the contact combustion system. When this sensor was used as a 6 V sensor based on the contact combustion system under the conditions of senior temperature in the range from 150 to 160 °C, D.C voltage of 6 V and 25 mA, the sensor provided the output of about 0 mV for carbon monoxide at the concentration of 500 ppm, .and also provided the output of 35 to 40 mV for hydrogen at the concentration of 500 ppm. When only the active section was subjected to the aging test by applying the voltage of 3.5 V for 99 days thereto, the average value of the sensitivity to hydrogen (output) at the concentration of 500 ppm was 32.5 mV, and that to carbon monoxide at the concentration of 500 ppm was 0.1 mV.
8
Claims (5)
1. A catalyst obtained by dispersing platinum black over a surface of a base metal compound oxide containing Co2O3, MnO2, CuO, and Cr2O3 to form an Ag2O layer on said platinum black layer, wherein said catalyst selectively oxi-dizes carbon monoxide in a gas mixture comprising carbon monoxide and hydrogen.
2. A contact combustion carbon monoxide sensor having a bridge circuit with an active section, wherein said carbon monoxide sensor has the catalyst according to claim 1 formed by dispersing platinum black on a surface of the coil with a base metal compound oxide containing Co2O3, MnO2, CuO and Cr2O3, further with .gamma.-Al2O3 mixed therein electrically deposited on the coil to form an Ag2O layer on the platinum black layer in the active section formed with a Pt line coil or an Fe-Pd line coil.
3. The catalyst according to claim 1, wherein said gas mixture comprising carbon monoxide and hydrogen is a hydro-gen gas which is a fuel for a fuel cell.
4. A catalyst obtained by dispersing Ag2O on a surface of a base metal compound oxide containing Co2O3, MnO2, CuO, and Cr2O3 to farm a platinum black layer on said Ag2O layer, wherein said catalyst selectively oxidizes hydrogen in a gas mixture comprising carbon monoxide and hydrogen.
5. A contact combustion hydrogen sensor having a bridge circuit with an active section provided therein, wherein said contact combustion hydrogen sensor has the catalyst according to claim 4 formed by dispensing Ag2O on a surface of a coil with a base metal compound oxide containing Co2O3, MnO2, CuO and Cr2O3 further with .gamma.-Al2O3 mixed therein electrically deposited thereon to form a platinum black layer on said Ag2O layer in the active section formed with a Pt line coil or an Fe-Pd line coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002353759A CA2353759A1 (en) | 2001-07-25 | 2001-07-25 | Oxidizing catalysts, carbon monoxide sensor, and hydrogen sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002353759A CA2353759A1 (en) | 2001-07-25 | 2001-07-25 | Oxidizing catalysts, carbon monoxide sensor, and hydrogen sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2353759A1 true CA2353759A1 (en) | 2003-01-25 |
Family
ID=4169555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002353759A Abandoned CA2353759A1 (en) | 2001-07-25 | 2001-07-25 | Oxidizing catalysts, carbon monoxide sensor, and hydrogen sensor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2353759A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8558538B2 (en) | 2008-09-29 | 2013-10-15 | Rosemount Aerospace Inc. | Blade tip clearance measurement sensor for gas turbine engines |
| US11636870B2 (en) | 2020-08-20 | 2023-04-25 | Denso International America, Inc. | Smoking cessation systems and methods |
| US11760169B2 (en) | 2020-08-20 | 2023-09-19 | Denso International America, Inc. | Particulate control systems and methods for olfaction sensors |
| US11760170B2 (en) | 2020-08-20 | 2023-09-19 | Denso International America, Inc. | Olfaction sensor preservation systems and methods |
| US11813926B2 (en) | 2020-08-20 | 2023-11-14 | Denso International America, Inc. | Binding agent and olfaction sensor |
| US11828210B2 (en) | 2020-08-20 | 2023-11-28 | Denso International America, Inc. | Diagnostic systems and methods of vehicles using olfaction |
| US11881093B2 (en) | 2020-08-20 | 2024-01-23 | Denso International America, Inc. | Systems and methods for identifying smoking in vehicles |
| US11932080B2 (en) | 2020-08-20 | 2024-03-19 | Denso International America, Inc. | Diagnostic and recirculation control systems and methods |
-
2001
- 2001-07-25 CA CA002353759A patent/CA2353759A1/en not_active Abandoned
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8558538B2 (en) | 2008-09-29 | 2013-10-15 | Rosemount Aerospace Inc. | Blade tip clearance measurement sensor for gas turbine engines |
| US8773115B2 (en) | 2008-09-29 | 2014-07-08 | Rosemount Aerospace Inc. | Blade tip clearance measurement sensor for gas turbine engines |
| US11636870B2 (en) | 2020-08-20 | 2023-04-25 | Denso International America, Inc. | Smoking cessation systems and methods |
| US11760169B2 (en) | 2020-08-20 | 2023-09-19 | Denso International America, Inc. | Particulate control systems and methods for olfaction sensors |
| US11760170B2 (en) | 2020-08-20 | 2023-09-19 | Denso International America, Inc. | Olfaction sensor preservation systems and methods |
| US11813926B2 (en) | 2020-08-20 | 2023-11-14 | Denso International America, Inc. | Binding agent and olfaction sensor |
| US11828210B2 (en) | 2020-08-20 | 2023-11-28 | Denso International America, Inc. | Diagnostic systems and methods of vehicles using olfaction |
| US11881093B2 (en) | 2020-08-20 | 2024-01-23 | Denso International America, Inc. | Systems and methods for identifying smoking in vehicles |
| US11932080B2 (en) | 2020-08-20 | 2024-03-19 | Denso International America, Inc. | Diagnostic and recirculation control systems and methods |
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