WO1999034199A1 - Metal oxide sensor for detecting nitrogen oxides - Google Patents
Metal oxide sensor for detecting nitrogen oxides Download PDFInfo
- Publication number
- WO1999034199A1 WO1999034199A1 PCT/US1998/025118 US9825118W WO9934199A1 WO 1999034199 A1 WO1999034199 A1 WO 1999034199A1 US 9825118 W US9825118 W US 9825118W WO 9934199 A1 WO9934199 A1 WO 9934199A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sensor
- catalyst
- metal oxide
- sensor system
- exhaust gas
- Prior art date
Links
- 229910044991 metal oxide Inorganic materials 0.000 title claims abstract description 45
- 150000004706 metal oxides Chemical class 0.000 title claims abstract description 45
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims abstract description 31
- 239000007789 gas Substances 0.000 claims abstract description 65
- 239000003054 catalyst Substances 0.000 claims abstract description 50
- 230000003647 oxidation Effects 0.000 claims abstract description 35
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 35
- 229910002091 carbon monoxide Inorganic materials 0.000 claims abstract description 23
- 230000001590 oxidative effect Effects 0.000 claims abstract description 11
- 239000000463 material Substances 0.000 claims description 27
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical group O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 27
- 239000004065 semiconductor Substances 0.000 claims description 15
- 230000003197 catalytic effect Effects 0.000 claims description 14
- 239000000758 substrate Substances 0.000 claims description 10
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 7
- 239000007769 metal material Substances 0.000 claims description 6
- 229930195733 hydrocarbon Natural products 0.000 claims description 5
- 229910052697 platinum Inorganic materials 0.000 claims description 5
- 229910002086 ceria-stabilized zirconia Inorganic materials 0.000 claims description 4
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 150000002430 hydrocarbons Chemical class 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 230000000694 effects Effects 0.000 claims description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052703 rhodium Inorganic materials 0.000 claims description 3
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 claims description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 2
- 230000008859 change Effects 0.000 claims description 2
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten(VI) oxide Inorganic materials O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 claims description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N zinc oxide Inorganic materials [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 2
- 239000004215 Carbon black (E152) Substances 0.000 claims 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 19
- 230000004044 response Effects 0.000 description 14
- 229910001887 tin oxide Inorganic materials 0.000 description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 239000011149 active material Substances 0.000 description 8
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 8
- 230000035945 sensitivity Effects 0.000 description 8
- 230000008901 benefit Effects 0.000 description 6
- -1 methane hydrocarbons Chemical class 0.000 description 5
- 239000010948 rhodium Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000011144 upstream manufacturing Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 2
- 229910002254 LaCoO3 Inorganic materials 0.000 description 1
- 229910002321 LaFeO3 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910002087 alumina-stabilized zirconia Inorganic materials 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000002800 charge carrier Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000001659 ion-beam spectroscopy Methods 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Natural products C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Inorganic materials O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000003878 thermal aging Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
-
- 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
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/42—Platinum
-
- 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
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/89—Catalysts 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
- B01J23/8906—Iron and noble metals
-
- 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
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/89—Catalysts 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
- B01J23/8926—Copper and noble metals
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G19/00—Compounds of tin
- C01G19/02—Oxides
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
- G01N33/0037—NOx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02518—Deposited layers
- H01L21/02521—Materials
- H01L21/02524—Group 14 semiconducting materials
- H01L21/02535—Group 14 semiconducting materials including tin
-
- 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
Definitions
- the invention relates to a gas sensor system for detecting low concentrations of NO ⁇ in a flowing gas stream and more particularly to a gas sensor system having increased sensitivity for NO x , comprising a sensor oxidation catalyst and a n-type metal oxide semiconductor sensor.
- Catalytic converters have been used on gasoline-fueled automobiles produced in the United States since the mid-1970's for the purpose of promoting the oxidation of unburned hydrocarbons (HCs) and of carbon monoxide (CO). Soon after their introduction, the converters were adapted to promote the chemical reduction of oxides of nitrogen (NO x ). At the present time these converters typically employ small amounts of platinum, palladium and rhodium dispersed over a high surface area particulate carrier vehicle which, in turn, is distributed as a thin, porous coating (sometimes called a washcoat) on the wall of a ceramic monolith substrate. These flow-through catalytic devices are housed in a suitable stainless steel container and placed in the exhaust stream under the vehicle downstream from the engine's exhaust manifold.
- this legislation requires that the exhaust from the catalytic converter be monitored, to determine when the steady-state conversion of regulated gases, such as the non-methane hydrocarbons, NO x , and CO, falls below between about 60-80%.
- regulated gases such as the non-methane hydrocarbons, NO x , and CO
- OBD-II legislation requires that for low emission vehicles the catalyst is considered to be malfunctioning when the HC, NO x , or CO emissions exceed 1.75 times the Federal Test Procedure (FTP) standard. Given these conditions, there is a strong interest in incorporating additional sensors to the vehicle; e.g., specifically NO x sensors. For a NO x sensor to be effective and useful there are certain requirements which the they must exhibit, including the ability to operate at temperatures from 200-800°C, as well as the ability to sense NO x concentrations as low as 25 ppm to those as high as 2,000 ppm.
- FTP Federal Test Procedure
- the sensor response time required for OBD-II monitoring must be on the order of 10 seconds or less, preferably as low as 1 second, while response time for engine feedback, generally needs to be on the order of 1 second, with times as quick as 100 milliseconds being preferred.
- the temperature of operation must be high, usually from 300°C to 700°C; an advantage for high temperature sensor applications.
- metal oxide semiconducting materials can be used as chemical sensors for detecting specific components of test gases, e.g., NO x in internal combustion engine exhaust gas. Ceramics which have been utilized include, SnO , doped SnO 2 (Ti, In), TiO 2 , WO 3 , Fe 2 O 3 , ZnO, LaFeO 3 , NiO-ZnO, Cr 2 O 3 -Nb 2 O 5 and YBa 2 Cu 3 O x , among many others.
- the advantages of these materials for gas sensor applications are several.
- the samples can readily be prepared as thin or thick films by methods including ion-beam sputtering, magnetron sputtering, screen printing, and sol-gel processing. Depending on the test conditions and the nature of the sample, these sensors can detect gases in concentrations ranging from 10 ppm to > 1,000 ppm. Response times as low as 1 second or less have been reported.
- Tin oxide (SnO 2 ) is a preferred metal oxide semiconducting material, and thus is widely used as the basis of solid state sensors.
- Tin (IV) oxide is an n-type semiconductor in which electrical conductivity occurs through negative charge carriers.
- the mechanism by which semiconducting ceramics such as SnO 2 respond to gases is by a change in the surface resistance of the materials upon the adsorption of a gas.
- the adsorbing gases react with the surface oxides on the SnO 2 .
- the resistance increases upon the absorption of an oxidizing gas such as NO x (NO or NO 2 ), and decreases upon the adsorption of a reducing gas such as CO. This can described via the following reactions.
- tin oxide is widely used, they do suffer a major drawback in that they are sensitive to many gases and worse they also exhibit some cross-sensitivities; i.e. the presence of one gas alters the sensitivity of the sensor to the presence of a second gas. Given the fact that SnO has been found to exhibit a good response to many gases, including NO, NO 2 , CH . C 3 H 8 , C 6 H ⁇ 4 ., CO, H 2 O, SO 2 , H 2 , and O 2 itself, this shortcoming is especially prevalent. As such, tin oxide sensors are not satisfactory in terms of their response to low concentrations of NO x .
- U.S. Pat. No. 5,624,640 discloses a sensor having increased sensitivity for detecting nitrogen oxides in a test gas.
- This sensor comprises a semiconducting metal oxide layer which is deposited on a ceramic substrate and whose electrical resistance provides information about the concentration of nitrogen oxides.
- the main components of the sensor comprise a converter layer which is deposited on the metal oxide layer and is made of a material which cause the oxidation of the combustible components of the test gas and converts the NO in the test gas into NO 2 or N 2 O .
- the converter layer comprises TiO and/or ZrO and/or SiO 2 and/or Al 2 O 3 and has a platinum content.
- the invention is directed, in its broadest sense, at a system and a method exhibiting an increased sensitivity for measuring the NO x concentration in a gas sample.
- the invention is based on the principle that tin oxide has been found to have no response to CO 2 , and only a slight response to H 2 O. In addition, it has been found that
- SnO 2 is more responsive to NO 2 than to NO, and the presence of NO actually reduces the sensitivity of the response to NO 2 .
- the sensor system for measuring the NO x concentration of a flowing gas stream comprises a sensor oxidation catalyst capable of both oxidizing CO and NO in the gas sample to CO 2 and NO 2 , respectively.
- the catalyst is inco ⁇ orated into the system so as to oxidize the CO and NO in the flowing gas stream prior to the gas stream contacting a metal oxide semiconducting sensor.
- an n- type semiconducting metal oxide sensor preferably tin oxide, whose electrical resistance varies in relation to the concentration of nitrogen oxides in the flowing gas stream.
- the semiconductor metal oxide sensor comprises tin oxide (SnO 2 ) and the oxidation catalyst inco ⁇ orated within the system is capable of oxidizing NO and/or
- CO in the temperature range of between about 200-500°C; more preferably in the temperature range of between about 250-400°C
- FIG. 1 is a block/flow diagram of the inventive sensor system
- FIG. 2 is a schematic diagram of an exhaust system inco ⁇ orating one embodiment of an inventive sensor system for measuring the NO x concentration of an exhaust gas stream
- FIG. 3 is a schematic diagram of an exhaust system incorporating another embodiment of an inventive sensor system for measuring the NO x concentration of an exhaust gas stream;
- FIGS. 4-8 illustrates three top views, a lateral view and a bottom view, respectively, of another embodiment of a sensor system for measuring the NO x concentration of an exhaust gas stream
- the present invention is directed at a system for measuring the NO x concentration of a gas sample.
- the system comprises a sensor oxidation catalyst and a downstream-positioned metal oxide semiconductor sensor, the sensor having an electrical resistance which varies in relation to the concentration of nitrogen oxides (NO x ) in the flowing gas stream.
- the sensor catalyst is capable of both oxidizing CO and NO in the gas sample to CO 2 and NO 2 respectively, the catalyst being positioned upstream of the metal oxide semiconducting to oxidize the CO and NO in the flowing gas stream prior to the gas stream contacting the metal oxide semiconducting sensor.
- a main catalytic converter 12 is located in the exhaust gas downstream of an internal combustion engine.
- the main catalytic converter 12 is capable of catalyzing the exhaust gas so as to reduce the pollutants present in the exhaust gas.
- the catalyst is a three-way catalyst which functions to oxidize both HCs and CO, as well as to reduce NO x , in the exhaust gas.
- the sensor system 10 generally comprises a sensor oxidation catalyst 14 and a n- type metal oxide semiconductor sensor 16 for directly measuring the NO x concentration in the exhaust gas.
- the sensor system 10 includes a housing 18, located downstream of the catalytic converter 12, within which are disposed both the sensor oxidation catalyst 14 and the metal oxide semiconductor sensor 16; supports 16A and 16B are used to support the sensor 16. Furthermore, the sensor communicates with a resistance measuring device which measures the increase of the electrical resistance of the metal oxide semiconducting sensor 16 in a known manner.
- the housing, sensor catalyst and the sensor could be located upstream of the main converter, thereby functioning to measure the concentration of an upstream portion of exhaust gas.
- FIG. 3 illustrated therein is another embodiment of the sensor system, wherein the tubular housing 26, is not only located downstream of the main catalytic converter 12, but is remote or off-line from the main flow of the exhaust gas.
- the sensor oxidation catalyst 28 comprises a tubular body comprised of a catalyst-support material and upon which a catalytically active metal material is deposited; one benefit of this embodiment is that the tubular sensor oxidation catalyst 28 can be uniformly heated by a heater 30 which surrounds the sensor oxidation catalyst thereby ensuring and accelerating the oxidation of the CO and NO in the flowing exhaust gas stream.
- the metal oxide semiconductor sensor 16 is located within a separate downstream housing portion 32.
- the metal oxide sensor utilized in the aforementioned two embodiments comprises any conventional metal oxide sensor, including, for example, SnO 2 , In 2 O 3 , Fe 2 O , ZnO, TiO , WO 3 , Nb 2 Os and the like.
- the preferred metal oxide sensor suitable for use in the instant invention, are disclosed in the following U.S. Patents., Pat. Nos. 4,592,967 (Ko atsu et al.), 4,535,351 (Sakai) and 5,427740 (Coles et al.).
- the metal oxide sensor may include a heater which increases the conductivity of the metal oxide.
- the sensor oxidation catalyst comprises a honeycomb body comprised of a catalyst-support material, upon which an appropriate catalytically active metal is deposited.
- the sensor oxidation catalyst comprises a tubular body comprised of a catalyst-support material and upon which an appropriately catalytically active metal catalyst is deposited.
- suitable catalytic-support materials include any high surface area material, preferably a ceramic material, including for example, silica, alumina, zirconia, ceria, titania and mixtures thereof.
- a preferred catalyst material comprises ⁇ -alumina.
- the suitable catalyst support material comprises an oxygen storage support material such as ceria-alumina, or preferentially, ceria-stabilized zirconia. Both oxygen storage support materials may result in improved activity of the catalyst for low temperature NO oxidation, as well as low temperature CO oxidation. Since normal engines typically operate at a slightly rich A/F ratio, i.e., an A/F ratio around 14.6, more oxygen is required during these rich conditions so as to ensure that this second catalytic reaction occurs and thus this downstream sensor functions properly. Although excess oxygen can be supplied by providing an air supply line, or the like, to the exhaust gas, it is preferred that the excess oxygen be supplied through the use of these catalyst-support materials comprised of an oxygen storage material. In this case, the catalyst-support materials are capable of storing and releasing oxygen depending upon the widely and rapidly varying oxygen concentration in the exhaust stream.
- the oxidation catalyst improves the selectivity and response of n-type metal oxide to NO x gases, by combining the metal oxide with suitable catalysts.
- Suitable catalytically active materials improve the responses of the metal oxide, e.g., tin oxide, both by (1) oxidizing CO (to which tin oxide responds) to CO 2 (to which tin oxide does not respond), thus removing the interfering signal of CO, and (2) more especially, by oxidizing NO to NO 2 .
- the ability to oxidize NO to NO 2 improves the response of the sensors to the NO x emissions from auto exhaust, since the NO x portion of the exhaust consists of approximately 90% NO and 10% NO 2 .
- SnO 2 it is more responsive to NO 2 than to NO, and the presence of NO tends to decrease the response to NO 2 .
- the catalyst serves to either fully oxidize the NO to NO 2 , and/or to maintain the molar ratio of NO to NO 2 at the equilibrium value for a given temperature.
- the advantage is that the sensor response no longer varies as the NO/NO 2 ratio varies, but gives a constant output that is dependent only on the total [NO+ NO ] concentration. It is also desirable to have the catalyst sufficiently active for NO oxidation and/or
- catalytically active materials include, for example, Pt, CuO-Pt, Fe 2 -CuO-Pt.
- the catalytically active material may be comprised of Rh.
- the catalyst support material comprise the aforementioned oxygen storage support material; i.e., either ceria-alumina or ceria-stabilized zirconia.
- Rh catalyst supported on ceria-stabilized zirconia is most suitable for applications where the NO x sensors would be primarily used for NO x detection for engine management in lean burn gasoline engines or diesel engines. In these highly oxidizing environments (6% O 2 ), the Rh catalyst may no longer be active for NO x reduction, but may be very suitable for relatively low temperature NO x oxidation.
- novel low temperature CO oxidation catalytically active material/support material combinations which may be used in the invention described herein include Au supported on MnO 2 , TiO 2 , Fe 2 O 3 or other oxides, as well as perovskite catalysts (e.g., LaCoO 3 ) alone or supported on ⁇ -alumina.
- the amount of the catalytically active metal material present in the sensor oxidation catalyst will be at least an effective amount and will depend, for example, on required catalyst activity, ease of uniform dispersion, and the type of substrate utilized. Generally, however, the level of catalytically active metal present will range from about 0.01% to 5.0%. and more preferably, 0.01% to 3.5%.
- the catalytically active material can be applied onto the catalyst-support material by any known method such as for example, by conventional washcoat or spraying techniques.
- the substrate is contacted with a slurry containing the catalytically active material and other components such as temporary binders, permanent binders or precursors, dispersants and other additives as needed.
- a slurry containing the catalytically active material and other components such as temporary binders, permanent binders or precursors, dispersants and other additives as needed.
- the slurry is then applied (for example, by repeated spraying, dipping or vacuum suction) to the substrate until the desired amount of catalytically active material has been applied.
- FIGS. 4-8 illustrated therein is another embodiment of the sensor system 10 which is embodied in the shape of a rod, which could be inco ⁇ orated into the exhaust system of either FIG. 2 or 3 in place of the sensor embodiments described therein.
- Substrate 34 is comprised of a catalytic support material which is electrically insulating and heat resistant; suitable materials for the catalytic support material are described above.
- Two strip conductors 36 are mounted on the surface of the substrate 34 which interlock in a comb-like fashion.
- a semiconducting metal oxide layer 38 of a thickness of 10-500 ⁇ m is suitably deposited over the strip conductors in the area of the interlocking ends; these strips communicate with a resistance measuring device which, as before, detects and measures any increase in electrical resistance of the semiconducting metal oxide layer 38.
- the metal oxide semiconductor comprises an n-type semiconductive metal oxide, preferably tin oxide (SnO 2 ).
- a sensor oxidation catalyst layer 40 is deposited at a suitable thickness of 10-100 ⁇ m over the metal oxide semiconducting layer; it is preferably comprised of the catalytically active metal material described above.
- the underside of the substrate is provided with a heater 42 which, as described before, is capable of both increasing the conductivity of the metal oxide and of ensuring and accelerating the oxidation of the NO and CO.
- a heater 42 which, as described before, is capable of both increasing the conductivity of the metal oxide and of ensuring and accelerating the oxidation of the NO and CO.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Materials Engineering (AREA)
- Combustion & Propulsion (AREA)
- Electrochemistry (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020007007240A KR20010033717A (en) | 1997-12-31 | 1998-12-01 | Metal oxide sensor for detecting nitrogen oxides |
EP98959588A EP1042666A1 (en) | 1997-12-31 | 1998-12-01 | Metal oxide sensor for detecting nitrogen oxides |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US7027297P | 1997-12-31 | 1997-12-31 | |
US60/070,272 | 1997-12-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999034199A1 true WO1999034199A1 (en) | 1999-07-08 |
Family
ID=22094264
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/025118 WO1999034199A1 (en) | 1997-12-31 | 1998-12-01 | Metal oxide sensor for detecting nitrogen oxides |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1042666A1 (en) |
KR (1) | KR20010033717A (en) |
CN (1) | CN1285914A (en) |
WO (1) | WO1999034199A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8161794B2 (en) | 2007-01-17 | 2012-04-24 | Toyota Jidosha Kabushiki Kaisha | Sulfur component detecting device |
US9389212B2 (en) | 2011-02-28 | 2016-07-12 | Honeywell International Inc. | NOx gas sensor including nickel oxide |
US11821884B2 (en) | 2018-02-21 | 2023-11-21 | Stmicroelectronics S.R.L. | Gas sensor device for detecting gases with large molecules |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100477422B1 (en) * | 2002-01-11 | 2005-03-23 | 동양물산기업 주식회사 | Method for semiconductor thin film gas sensor in order to detecting an ammonia gas and its device |
CN1296702C (en) * | 2003-09-30 | 2007-01-24 | 鸿富锦精密工业(深圳)有限公司 | Zinc oxide gas sensing device |
JP4634720B2 (en) * | 2004-01-20 | 2011-02-16 | サントリーホールディングス株式会社 | Gas detection method and detection apparatus |
KR101113315B1 (en) * | 2009-11-06 | 2012-03-13 | 광주과학기술원 | Gas sensor having catalyst layer and method for operating the same |
CN102806091B (en) * | 2012-06-29 | 2016-03-09 | 中国第一汽车股份有限公司 | A kind of novel composite catalyst material that can be used for NOx and detect |
CN102980916A (en) * | 2012-11-19 | 2013-03-20 | 中国科学院上海硅酸盐研究所 | Zirconia-based NOx sensor and preparation method thereof |
CN104792846B (en) * | 2014-12-10 | 2017-10-03 | 中国第一汽车股份有限公司 | Available for NOXThe Multi-function protective cover and its coating production of sensor |
TWI579561B (en) * | 2016-06-22 | 2017-04-21 | 國立成功大學 | Cerium oxide ph sensor and method of producing the same |
CN106093140B (en) * | 2016-07-19 | 2019-10-25 | 山东大学 | For NO2The composite construction doped air-sensitive material of gas, gas sensor and preparation method thereof and application |
CN110687104B (en) * | 2019-11-12 | 2021-08-13 | 北京联合大学 | Cross sensitive material of carbon monoxide and trimethylamine |
ES2890726B8 (en) | 2020-07-10 | 2023-05-03 | Consejo Superior Investigacion | RESISTIVE CHEMICAL SENSOR FOR THE DETECTION OF NO2 |
CN112067607B (en) * | 2020-09-09 | 2022-04-15 | 深圳九星印刷包装集团有限公司 | Carbon monoxide indicating device |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4457161A (en) * | 1980-10-09 | 1984-07-03 | Hitachi, Ltd. | Gas detection device and method for detecting gas |
US4592967A (en) * | 1983-02-03 | 1986-06-03 | New Cosmos Electric Co., Ltd | Gas sensor of mixed oxides |
JPH0359450A (en) * | 1989-07-28 | 1991-03-14 | Kurabe:Kk | Gas sensitive element |
RU2011985C1 (en) * | 1992-07-22 | 1994-04-30 | Владимир Васильевич Коновалов | Gas transducer sensing element |
US5389340A (en) * | 1989-12-28 | 1995-02-14 | Tokuyama Corporation | Module and device for detecting NOX gas |
US5624640A (en) * | 1993-10-12 | 1997-04-29 | Robert Bosch Gmbh | Sensor for detecting nitrogen oxide |
US5705129A (en) * | 1995-04-10 | 1998-01-06 | Ngk Insulators, Ltd. | NOx sensor |
US5810984A (en) * | 1996-04-24 | 1998-09-22 | Osaka Gas Co., Ltd. | Nitrogen oxide sensor and method of manufacturing the sensor |
-
1998
- 1998-12-01 KR KR1020007007240A patent/KR20010033717A/en not_active Application Discontinuation
- 1998-12-01 WO PCT/US1998/025118 patent/WO1999034199A1/en not_active Application Discontinuation
- 1998-12-01 EP EP98959588A patent/EP1042666A1/en not_active Withdrawn
- 1998-12-01 CN CN98812845A patent/CN1285914A/en active Pending
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4457161A (en) * | 1980-10-09 | 1984-07-03 | Hitachi, Ltd. | Gas detection device and method for detecting gas |
US4592967A (en) * | 1983-02-03 | 1986-06-03 | New Cosmos Electric Co., Ltd | Gas sensor of mixed oxides |
JPH0359450A (en) * | 1989-07-28 | 1991-03-14 | Kurabe:Kk | Gas sensitive element |
US5389340A (en) * | 1989-12-28 | 1995-02-14 | Tokuyama Corporation | Module and device for detecting NOX gas |
RU2011985C1 (en) * | 1992-07-22 | 1994-04-30 | Владимир Васильевич Коновалов | Gas transducer sensing element |
US5624640A (en) * | 1993-10-12 | 1997-04-29 | Robert Bosch Gmbh | Sensor for detecting nitrogen oxide |
US5705129A (en) * | 1995-04-10 | 1998-01-06 | Ngk Insulators, Ltd. | NOx sensor |
US5810984A (en) * | 1996-04-24 | 1998-09-22 | Osaka Gas Co., Ltd. | Nitrogen oxide sensor and method of manufacturing the sensor |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8161794B2 (en) | 2007-01-17 | 2012-04-24 | Toyota Jidosha Kabushiki Kaisha | Sulfur component detecting device |
US9389212B2 (en) | 2011-02-28 | 2016-07-12 | Honeywell International Inc. | NOx gas sensor including nickel oxide |
US9964507B2 (en) | 2011-02-28 | 2018-05-08 | Honeywell International Inc. | NOx gas sensor including nickel oxide |
US11821884B2 (en) | 2018-02-21 | 2023-11-21 | Stmicroelectronics S.R.L. | Gas sensor device for detecting gases with large molecules |
Also Published As
Publication number | Publication date |
---|---|
CN1285914A (en) | 2001-02-28 |
KR20010033717A (en) | 2001-04-25 |
EP1042666A1 (en) | 2000-10-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6109095A (en) | Metal oxide semiconductor catalyst hydrocarbon sensor | |
Meixner et al. | Thin-film gas sensors based on semiconducting metal oxides | |
WO1999034199A1 (en) | Metal oxide sensor for detecting nitrogen oxides | |
US5630920A (en) | Electrochemical sensor for determining the oxygen concentration in gas mixtures | |
Pijolat et al. | Gas detection for automotive pollution control | |
KR100484688B1 (en) | Engine Exhaust Gas Treatment System and How to Use | |
EP1098702B1 (en) | Exhaust gas catalyst comprising rhodium, zirconia, ceria and lanthanum oxide | |
US5444974A (en) | On-board automotive exhaust catalyst monitoring with a calorimetric sensor | |
CN1124522A (en) | Sensor to determine the gas component concentration in gas mixtures | |
US20030062264A1 (en) | Apparatus for measuring concentration of ammonia gas | |
EP0605995B1 (en) | A two-stage catalyst system for internal combustion engine | |
US4297192A (en) | Catalyst supported oxygen sensor element and a method of manufacturing same | |
EP1867389A1 (en) | Apparatus for purifying exhaust gas and catalyst for purifying exhaust gas | |
US6242263B1 (en) | Automotive hydrocarbon sensor | |
US6592823B1 (en) | Sensor for detecting the instantaneous concentrations of a plurality of gas constituents in a gas | |
EP2078561A1 (en) | Exhaust gas purification catalyst, exhaust gas purification system, and exhaust gas purification method | |
US5758489A (en) | Sulfur tolerant Pt/lithium NOx traps | |
US5939037A (en) | Sulfur tolerant NOx traps highly loaded with sodium or potassium | |
EP0849588A2 (en) | Automotive hydrocarbon sensor | |
US6103080A (en) | Hydrocarbon sensors and materials therefor | |
US6037183A (en) | Automotive hydrocarbon sensor system | |
JPH10332674A (en) | Hydrocarbon sensor device of automobile | |
JP4375336B2 (en) | Gas sensor and gas detection method | |
US6344173B1 (en) | Automotive hydrocarbon sensor | |
JP5028453B2 (en) | Gas sensor and gas detection method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 98812845.4 Country of ref document: CN |
|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): CN JP KR |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE |
|
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 1020007007240 Country of ref document: KR |
|
ENP | Entry into the national phase |
Ref document number: 2000 526800 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1998959588 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 1998959588 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 1020007007240 Country of ref document: KR |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1020007007240 Country of ref document: KR |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1998959588 Country of ref document: EP |