JP6364356B2 - Gas detection method and gas sensor - Google Patents

Description

  The present invention relates to a gas detection method and a gas sensor.

  Mercaptans such as methyl mercaptan and hydrogen sulfide are considered as substances that cause malodors, and various problems occur when mercaptans or hydrogen sulfide are released into the atmosphere. Since mercaptan and hydrogen sulfide have an odor threshold value on the order of ppb, a gas sensor with high sensitivity to mercaptan and hydrogen sulfide is required to measure odor.

  Patent Document 1 discloses a gas detection element that includes a gas sensitive part and a detection electrode that detects an electric resistance value of the gas sensitive part, and detects a gas to be detected based on a change in electric resistance of the gas sensitive part. Yes. At this time, the gas sensitive part is composed mainly of cerium oxide, and the gas to be detected is at least one of an oxygen-containing organic compound and a sulfur-containing compound.

JP 2010-2335 A

  However, it is desired to suppress the influence of hydrogen contained in the air when detecting the gas to be detected.

  An object of one embodiment of the present invention is to provide a gas detection method and a gas sensor that have high sensitivity to mercaptans and hydrogen sulfide and low sensitivity to hydrogen in view of the problems of the above-described conventional technology.

  One aspect of the present invention is a method for detecting a gas using a gas sensor, the gas sensor including a gas sensitive layer and an electrode for detecting an electrical resistance of the gas sensitive layer, wherein the gas sensitive layer is oxidized. It contains titanium and / or cerium oxide and vanadium oxide, the content of titanium oxide and / or cerium oxide is 50 mass% or more and 99 mass% or less, and the content of vanadium oxide is 1 mass% or more and 15 mass% or less. And the gas is mercaptan or hydrogen sulfide.

One aspect of the present invention is a gas sensor used for detection of mercaptan or hydrogen sulfide, which includes a gas-sensitive layer and an electrode that detects electric resistance of the gas-sensitive layer, and the gas-sensitive layer includes titanium oxide and / or Or it contains cerium oxide and vanadium oxide , the content of titanium oxide and / or cerium oxide is 50 mass% or more and 99 mass% or less, and the content of vanadium oxide is 1 mass% or more and 15 mass% or less.

  According to one embodiment of the present invention, it is possible to provide a gas detection method and a gas sensor that have high sensitivity to mercaptans and hydrogen sulfide and low sensitivity to hydrogen.

It is a top view which shows an example of the gas sensor before a gas sensitive layer is formed. It is a surface view which shows an example of a gas sensor. It is a figure which shows the cross section in the A-A 'line | wire of the gas sensor of FIG. It is a figure explaining the mechanism in which the electrical resistance of the gas sensitive layer of FIG. 2 changes. It is a figure which shows the electrical resistance of the gas sensitive layer at the time of exposing the gas sensor of Example 3 to the synthetic air containing methyl mercaptan. It is a figure which shows the electrical resistance of the gas sensitive layer at the time of exposing the gas sensor of Example 3 to the synthetic air containing hydrogen sulfide. It is a figure which shows the electrical resistance of the gas sensitive layer at the time of exposing the gas sensor of Example 3 to the synthetic air containing hydrogen.

  Next, the form for implementing this invention is demonstrated.

  The gas detection method is a method of detecting gas using a gas sensor. At this time, the gas sensor has a gas sensitive layer and an electrode for detecting the electric resistance of the gas sensitive layer, and the gas is mercaptan or hydrogen sulfide.

  Although it does not specifically limit as a mercaptan, Methyl mercaptan, ethyl mercaptan, isopropyl mercaptan, n-propyl mercaptan, etc. are mentioned.

  Next, the configuration of the gas sensor will be described with reference to FIGS.

  FIG. 1 shows an example of a gas sensor before the gas sensitive layer is formed. 1A and 1B are a front view and a back view, respectively.

  Comb electrodes 2 and comb electrodes 3 for detecting the electric resistance of the gas sensitive layer are formed on the surface of the substrate 1 (see FIG. 1A). On the other hand, a heater 4 is formed on the back surface of the substrate 1 (see FIG. 1B).

  The substrate 1 is not particularly limited as long as it has heat resistance and insulation, and examples thereof include a ceramic substrate such as alumina and zirconia, a silicon substrate with a thermal oxide film, and the like.

  Although it will not specifically limit as a material which comprises the comb-tooth electrode 2 and the comb-tooth electrode 3 if it has electrical conductivity, Platinum, gold | metal | money, etc. are mentioned.

  The comb-tooth electrode 2 and the comb-tooth electrode 3 are arranged so as to face each other.

  The distance between the comb electrode 2 and the comb electrode 3 is usually 50 to 700 μm, and preferably 100 to 500 μm.

  Although it does not specifically limit as a formation method of the comb-tooth electrode 2 and the comb-tooth electrode 3, Screen printing method, sputtering method, a vacuum evaporation method, etc. are mentioned.

  In addition, as an electrode which detects the electrical resistance of a gas sensitive layer, it is not limited to a comb-tooth electrode, You may use a plane electrode etc.

  The material constituting the heater 4 is not particularly limited as long as the gas sensitive layer can be heated by resistance heating, and platinum and the like can be cited.

  The temperature at which the gas sensitive layer is heated is usually 300 to 500 ° C, preferably 300 to 450 ° C. When the temperature at which the gas sensitive layer is heated is 300 ° C. or higher, the sensitivity of the gas sensor 10 to mercaptan and hydrogen sulfide can be further increased, and when the temperature is 500 ° C. or lower, deterioration of the performance of the gas sensor is suppressed. Can do.

  In addition, the method of heating a gas sensitive layer is not limited to the method of heating by resistance heating, The method of heating by external heating, such as an electric furnace, etc. may be sufficient.

  FIG. 2 shows an example of a gas sensor.

  In the gas sensor 10, the gas sensitive layer 5 is formed so as to cover the comb electrode 2 and the comb electrode 3.

  The shape and size of the gas sensitive layer 5 are not particularly limited.

  In FIG. 3, the cross section in the A-A 'line | wire of the gas sensor 10 is shown.

  The gas sensitive layer 5 is formed so as to fill a space between the comb-tooth electrode 2 and the comb-tooth electrode 3 in order to ensure a sufficient contact area with the comb-tooth electrode 2 and the comb-tooth electrode 3. It is preferable.

The gas sensitive layer 5 contains titanium oxide (TiO ₂ ) and / or cerium oxide (CeO ₂ ) and vanadium oxide (V ₂ O ₅ ), and may further contain tungsten oxide (WO ₃ ).

  The content of titanium oxide and / or cerium oxide in the gas sensitive layer 5 is 50 to 99% by mass, and preferably 50 to 97% by mass. When the content of titanium oxide and / or cerium oxide in the gas sensitive layer 5 is less than 50% by mass, the sensitivity of the gas sensor 10 to hydrogen increases, and when it exceeds 99% by mass, the electric resistance of the gas sensitive layer 5 increases. growing.

  The content of vanadium oxide in the gas sensitive layer 5 is 1 to 15% by mass, preferably 1.5 to 10% by mass, and more preferably 3 to 10% by mass. When the content of vanadium oxide in the gas sensitive layer 5 is less than 1% by mass, the sensitivity of the gas sensor 10 to hydrogen increases, and when it exceeds 15% by mass, the sensitivity of the gas sensor 10 to mercaptan and hydrogen sulfide decreases.

  The content of tungsten oxide in the gas sensitive layer 5 is usually 49% by mass or less, and preferably 45% by mass or less. When the content of tungsten oxide in the gas sensitive layer 5 is 49% by mass or less, the sensitivity of the gas sensor 10 to hydrogen is further reduced.

Examples of commercially available titanium oxide include AEROXIDE TiO ₂ P25 (manufactured by Nippon Aerosil Co., Ltd.), TiO ₂ nanopowder (manufactured by Sigma Aldrich Co., Ltd.) and the like.

Examples of commercially available products of cerium oxide include core-shell ceria nanoparticles (made by Hokuko Chemical Co., Ltd.), CeO ₂ nanopowder (made by Sigma Aldrich), and the like.

Examples of commercially available vanadium oxide materials include NH ₄ VO ₃ (manufactured by Sigma Aldrich).

Examples of commercially available tungsten oxide raw materials include (NH ₄ ) ₁₀ H ₂ (W ₂ O ₇ ) ₆ · xH ₂ O (manufactured by Sigma Aldrich).

  Vanadium oxide and tungsten oxide are preferably nano-sized particles. Thereby, the surface area of powder increases and the area which reacts with the gas of the gas sensitive layer 5 increases.

  Vanadium oxide and tungsten oxide are preferably uniformly dispersed on the surface of titanium oxide and / or cerium oxide. Specifically, after titanium oxide and / or cerium oxide is dispersed in water, a solution containing a tungsten component and a vanadium component is poured, while stirring using a stirrer or the like, the water is evaporated and baked to oxidize the metal. It is preferable to produce a powder of the product.

  The gas sensitive layer 5 may further contain a noble metal catalyst. Thereby, the sensitivity with respect to the mercaptan and hydrogen sulfide of the gas sensor 10 can further be improved.

  Although it does not specifically limit as an element which comprises a noble metal catalyst, Platinum, gold | metal | money, palladium, silver etc. are mentioned.

  The gas sensitive layer 5 may further contain a metal oxide other than the above, such as tin (IV) oxide.

  The gas sensitive layer 5 is preferably substantially made of a metal oxide.

  The method for forming the gas sensitive layer 5 is not particularly limited. However, the above metal oxide powder, or a powder containing titanium oxide and / or cerium oxide, vanadium oxide, and tungsten oxide, a binder, and an organic material. Examples include a method of baking after applying a paste mixed with a solvent.

  The firing temperature is usually 300 to 800 ° C, preferably 500 to 750 ° C, and particularly preferably around 700 ° C.

  The binder is not particularly limited, and examples thereof include cellulose, ethyl cellulose, hydroxyethyl cellulose and the like.

  Although it does not specifically limit as an organic solvent, Toluene, xylene, terpineol, ethylene glycol, etc. are mentioned.

  When the mercaptan or hydrogen sulfide contacts the gas sensitive layer 5, the gas sensor 10 can detect gas because the electric resistance of the gas sensitive layer 5 changes.

  The mechanism by which the electric resistance of the gas sensitive layer 5 changes will be described with reference to FIG.

It is assumed that X (X = 4) metal oxide powders 5a constituting the gas sensitive layer 5 are arranged between the comb electrode 2 and the comb electrode 3. At this time, the electrical resistance of the comb-tooth electrode 2 and the comb-tooth electrode 3 is Re, the grain boundary resistance of the metal oxide powder 5a is Rb, and the metal oxide powder 5a is connected between the comb-tooth electrode 2 and the comb-tooth electrode 3. When the interface resistance is Ri, the electric resistance R of the gas sensitive layer 5 measured by the two-terminal method is expressed by the formula R = 2Re + 2Ri + (X−1) Rb.
It is represented by Next, when the gas sensor 10 is exposed to mercaptan or hydrogen sulfide, the lattice oxygen of the metal oxide powder 5a is consumed, and the electrons of the lattice oxygen are returned to the metal oxide powder 5a. Since the metal oxide powder 5a is an n-type semiconductor, the number of carriers is increased by returning electrons, and the electric resistance R of the gas sensitive layer 5 is reduced. Here, since Re is constant regardless of the atmosphere, Ri and Rb are small. Thus, since the electric resistance R of the gas sensitive layer 5 changes by exposing the gas sensor 10 to mercaptan or hydrogen sulfide, mercaptan or hydrogen sulfide can be detected.

  The sensitivity of the gas sensor 10 to mercaptan or hydrogen sulfide is the ratio Ra of the electrical resistance Ra of the gas sensitive layer 5 when exposed to air to the electrical resistance Rg of the gas sensitive layer 5 when exposed to mercaptan or hydrogen sulfide. / Rg, which can be an index of the performance of the gas sensor. The sensitivity of the gas sensor 10 to mercaptan or hydrogen sulfide usually increases in proportion to the concentration of mercaptan or hydrogen sulfide. For this reason, the concentration of mercaptan or hydrogen sulfide can be measured from the sensitivity of the gas sensor 10 to mercaptan or hydrogen sulfide.

  The gas sensor 10 can detect mercaptans and hydrogen sulfide from a low concentration to a high concentration.

  The sensitivity of the gas sensor 10 to 750 ppm of hydrogen is usually 1.20 or less, and preferably 1.08 or less. For this reason, even in an atmosphere where 750 ppm of hydrogen coexists, mercaptan and hydrogen sulfide can be detected without being inhibited by hydrogen.

  By adjusting the temperature at which the gas sensitive layer 5 is heated, the gas sensor 10 can make the sensitivity to mercaptan higher than the sensitivity to hydrogen sulfide or make the sensitivity to mercaptan lower than the sensitivity to hydrogen sulfide.

  Therefore, if the gas sensor 10 having higher sensitivity to mercaptan than the sensitivity to hydrogen sulfide and the gas sensor 10 having lower sensitivity to mercaptan than the sensitivity to hydrogen sulfide are installed in an atmosphere in which mercaptan and hydrogen sulfide coexist, The concentration can also be measured.

  The gas sensor 10 can detect mercaptan and hydrogen sulfide of 500 ppb or more.

  The gas sensor 10 can be applied to a detector of mercaptan and hydrogen sulfide contained in a biological gas, a simple inspection device, and the like.

  Next, the present invention will be specifically described based on examples, but the present invention is not limited to the examples. In addition, a part means a mass part.

[Example 1]
A platinum paste TR-7091T (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) is screen-printed on the surface of a 6.35 mm × 50.8 mm × 635 μm alumina substrate 1 (manufactured by Koyo Seiko Co., Ltd.), followed by firing at 1400 ° C. for 2 hours. The comb electrode 2 and the comb electrode 3 were formed. The comb-tooth electrode 2 and the comb-tooth electrode 3 had a width of 100 μm, and the distance between the comb-tooth electrode 2 and the comb-tooth electrode 3 was 100 μm, and was formed in a region of 5.3 mm × 6.3 mm. Next, Pt paste TR-7091T (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was screen-printed on the back surface of the substrate 1 and then baked at 1400 ° C. for 2 hours to form a heater 4 (see FIG. 1).

NH ₄ VO ₃ (manufactured by Sigma Aldrich) as a raw material of vanadium oxide, AEROXIDE TiO ₂ P25 (manufactured by Nippon Aerosil Co., Ltd.) as titanium oxide, (NH ₄ ) ₁₀ H ₂ (W ₂ O ₇ as a raw material of tungsten oxide) ) ₆ · xH ₂ O (manufactured by Sigma Aldrich) was mixed to obtain a mixed powder. At this time, the raw material of vanadium oxide, the raw material of titanium oxide, and tungsten oxide were mixed so that the mass ratio of vanadium oxide, titanium oxide, and tungsten oxide might be 3:87:10.

  A paste was obtained by mixing 60 parts of the mixed powder and 40 parts of a vehicle in which ethyl cellulose (manufactured by Sigma Aldrich) and terpineol were mixed at a mass ratio of 1: 9.

  After apply | coating the obtained paste on the comb-tooth electrode 2 and the comb-tooth electrode 3, it baked at 700 degreeC using the baking furnace, the gas sensitive layer 5 was formed, and the gas sensor 10 was obtained.

  After the gas sensor 10 was installed in the sample holder, the heater 5 was energized and heated by resistance heating so that the gas sensitive layer 5 became 300 ° C. Synthetic air in which nitrogen and oxygen were mixed at a volume ratio of 4: 1 was passed through the sample holder at a flow rate of 200 mL / min, and the electric resistance of the gas sensitive layer 5 was measured. The electric resistance of the gas sensitive layer 5 was measured at intervals of 10 seconds by a two-terminal method using a 2700 type multichannel digital multimeter DMM (manufactured by Keithley Instruments). At this time, the electric resistance of the gas sensitive layer 5 one hour after the electric resistance of the gas sensitive layer 5 was stabilized was defined as Ra. Next, after introducing methyl mercaptan standard gas (manufactured by Taiyo Nippon Sanso Co., Ltd.) into nitrogen, synthetic air in which nitrogen and oxygen into which methyl mercaptan standard gas was introduced was mixed at a volume ratio of 4: 1 was added at 200 mL / min. The sample was passed through the sample holder at a flow rate, and the electric resistance of the gas sensitive layer 5 was measured in the same manner as described above. At this time, the concentration of methyl mercaptan in the synthetic air was 50 ppb, and the electric resistance of the gas sensitive layer 5 after flowing synthetic air through the sample holder for 1 hour was Rg. Furthermore, synthetic air in which nitrogen and oxygen were mixed at a volume ratio of 4: 1 was passed through the sample holder at a flow rate of 200 mL / min, and the electrical resistance of the gas sensitive layer 5 was measured. Next, the electric resistance Rg of the gas sensitive layer 5 was measured in the same manner as above except that the concentration of methyl mercaptan in the synthetic air was changed to 250 ppb. Furthermore, synthetic air in which nitrogen and oxygen were mixed at a volume ratio of 4: 1 was passed through the sample holder at a flow rate of 200 mL / min, and the electrical resistance of the gas sensitive layer 5 was measured. Next, the electric resistance Rg of the gas sensitive layer 5 was measured in the same manner as above except that the concentration of methyl mercaptan in the synthetic air was changed to 500 ppb.

  The electrical resistance Rg of the gas sensitive layer 5 was measured in the same manner as above except that a hydrogen sulfide standard gas (manufactured by Taiyo Nippon Sanso) was used instead of the methyl mercaptan standard gas (manufactured by Taiyo Nippon Sanso). did.

  Instead of methyl mercaptan standard gas (manufactured by Taiyo Nippon Sanso), hydrogen standard gas (manufactured by Taiyo Nippon Sanso) is used, and the concentration of hydrogen in the synthesis air is increased from 250 ppb, 500 ppb and 750 ppb to 250 ppm, 500 ppm and 750 ppm. The electrical resistance Rg of the gas sensitive layer 5 was measured in the same manner as above except that the change was made.

  The sensitivity Ra / Rg of the gas sensor 10 for methyl mercaptan, hydrogen sulfide, and hydrogen was calculated.

[Example 2]
The sensitivity Ra / Rg of the gas sensor 10 with respect to methyl mercaptan, hydrogen sulfide, and hydrogen was determined in the same manner as in Example 1 except that the gas sensitive layer 5 was heated by resistance heating so as to be 350 ° C.

[Example 3]
The sensitivity Ra / Rg of the gas sensor 10 with respect to methyl mercaptan, hydrogen sulfide, and hydrogen was determined in the same manner as in Example 1 except that the gas sensitive layer 5 was heated by resistance heating so that the temperature became 400 ° C.

  5-7 shows the electrical resistance of the gas sensitive layer 5 when the gas sensor is exposed to synthetic air containing methyl mercaptan, hydrogen sulfide or hydrogen. 5 and 6, when the gas sensor 10 is exposed to synthetic air containing methyl mercaptan or hydrogen sulfide, the electrical resistance of the gas sensitive layer 5 decreases, and when the gas sensor 10 is exposed to synthetic air not containing methyl mercaptan or hydrogen sulfide, It turns out that the electrical resistance of the gas sensitive layer 5 returns.

[Example 4]
The sensitivity Ra / Rg of the gas sensor 10 with respect to methyl mercaptan, hydrogen sulfide, and hydrogen was determined in the same manner as in Example 1 except that the gas sensitive layer 5 was heated by resistance heating so that the temperature became 450 ° C.

[Example 5]
The sensitivity Ra / Rg of the gas sensor 10 with respect to methyl mercaptan, hydrogen sulfide, and hydrogen was determined in the same manner as in Example 3 except that the distance between the comb electrode 2 and the comb electrode 3 was changed to 175 μm.

[Example 6]
The sensitivity Ra / Rg of the gas sensor 10 for methyl mercaptan, hydrogen sulfide and hydrogen was determined in the same manner as in Example 3 except that the distance between the comb electrode 2 and the comb electrode 3 was changed to 500 μm.

[Example 7]
Example 3 except that when the mixed powder was prepared, the raw material of tungsten oxide was not added, and the raw material of vanadium oxide and titanium oxide were mixed so that the mass ratio of vanadium oxide and titanium oxide was 3:97. In the same manner, the sensitivity Ra / Rg of the gas sensor 10 to methyl mercaptan, hydrogen sulfide, and hydrogen was determined.

[Example 8]
Except for mixing the raw material of vanadium oxide, the raw material of titanium oxide and the tungsten oxide so that the mass ratio of vanadium oxide, titanium oxide and tungsten oxide is 10:80:10 when preparing the mixed powder, Example 1, the sensitivity Ra / Rg of the gas sensor 10 for methyl mercaptan, hydrogen sulfide, and hydrogen was determined.

[Example 9]
Other than mixing the raw material of vanadium oxide, the raw material of titanium oxide and tungsten oxide so that the mass ratio of vanadium oxide, titanium oxide and tungsten oxide is 1.5: 88.5: 10 when preparing the mixed powder In the same manner as in Example 1, the sensitivity Ra / Rg of the gas sensor 10 for methyl mercaptan, hydrogen sulfide, and hydrogen was determined.

[Example 10]
In producing the mixed powder, methyl mercaptan and sulfide of the gas sensor 10 were obtained in the same manner as in Example 9 except that core-shell type ceria nanoparticles (made by Hokuko Chemical Co., Ltd.) as cerium oxide were used instead of titanium oxide. Sensitivity Ra / Rg to hydrogen and hydrogen was determined.

[Example 11]
Except for mixing the raw material of vanadium oxide, the raw material of titanium oxide and tungsten oxide so that the mass ratio of vanadium oxide, titanium oxide and tungsten oxide was 3:77:20 when producing the mixed powder, the examples 3, the sensitivity Ra / Rg of the gas sensor 10 for methyl mercaptan, hydrogen sulfide, and hydrogen was determined.

[Example 12]
Except for mixing the raw material of vanadium oxide, the raw material of titanium oxide, and the tungsten oxide so that the mass ratio of vanadium oxide, titanium oxide, and tungsten oxide is 3:52:45 when preparing the mixed powder. 3, the sensitivity Ra / Rg of the gas sensor 10 for methyl mercaptan, hydrogen sulfide, and hydrogen was determined.

[Example 13]
When preparing the mixed powder, core-shell ceria nanoparticles (made by Hokuko Chemical Co., Ltd.) as cerium oxide are further added, and the mass ratio of vanadium oxide, titanium oxide, cerium oxide and tungsten oxide is 3: 80: 7: 10. The sensitivity Ra / Rg of the gas sensor 10 to methyl mercaptan, hydrogen sulfide, and hydrogen is the same as in Example 3 except that the raw materials of vanadium oxide, titanium oxide, cerium oxide, and tungsten oxide are mixed so that Asked.

[Comparative Example 1]
The sensitivity Ra / Rg of the gas sensor 10 with respect to methyl mercaptan, hydrogen sulfide and hydrogen is the same as in Example 3 except that AEROXIDE TiO ₂ P25 (manufactured by Nippon Aerosil Co., Ltd.) as titanium oxide is used instead of the mixed powder. Asked.

[Comparative Example 2]
The sensitivity Ra / Rg of the gas sensor 10 to methyl mercaptan, hydrogen sulfide and hydrogen in the same manner as in Example 3 except that core-shell ceria nanoparticles (made by Hokuko Chemical Co., Ltd.) as cerium oxide were used instead of the mixed powder. Asked.

[Comparative Example 3]
Example 3 except that the raw material of vanadium oxide was not added and the raw materials of titanium oxide and tungsten oxide were mixed so that the mass ratio of titanium oxide and tungsten oxide was 90:10 when preparing the mixed powder. In the same manner, the sensitivity Ra / Rg of the gas sensor 10 to methyl mercaptan, hydrogen sulfide, and hydrogen was determined.

  Table 1 shows the characteristics of the gas sensor 10.

  Table 2 shows the sensitivity Ra / Rg of the gas sensor 10 with respect to methyl mercaptan, hydrogen sulfide, and hydrogen.

  From Table 2, it can be seen that Examples 1 to 13 have high sensitivity to methyl mercaptan and hydrogen sulfide and low sensitivity to hydrogen. For this reason, methyl mercaptan and hydrogen sulfide can be detected while suppressing the influence of hydrogen contained in the air.

  In contrast, in Comparative Examples 1 and 2, since the gas sensitive layer 5 is made of titanium oxide or cerium oxide, the electric resistance of the gas sensitive layer 5 is large (> 120 MΩ). For this reason, the sensitivity of the gas sensor 10 to methyl mercaptan, hydrogen sulfide, and hydrogen could not be obtained.

  In Comparative Example 3, since the gas sensitive layer 5 does not contain vanadium oxide, the sensitivity to hydrogen is high. For this reason, the influence of hydrogen contained in the air cannot be suppressed.

DESCRIPTION OF SYMBOLS 1 Substrate 2, 3 Comb electrode 4 Heater 5 Gas sensitive layer 5a Metal oxide powder 10 Gas sensor

Claims (7)

A method of detecting gas using a gas sensor,
The gas sensor has a gas sensitive layer and an electrode for detecting an electric resistance of the gas sensitive layer,
The gas sensitive layer contains titanium oxide and / or cerium oxide and vanadium oxide, the content of titanium oxide and / or cerium oxide is 50 mass% or more and 99 mass% or less, and the content of vanadium oxide is 1 Mass% or more and 15 mass% or less,
The gas detection method according to claim 1, wherein the gas is mercaptan or hydrogen sulfide.   The gas detection method according to claim 1, wherein the gas sensitive layer further contains tungsten oxide, and the content of tungsten oxide is 49 mass% or less.   The gas detection method according to claim 1, wherein the mercaptan is methyl mercaptan.   The gas detection method according to claim 1, wherein the gas is detected by heating the gas sensitive layer to a temperature of 300 ° C. or more and 500 ° C. or less. A gas sensor used to detect mercaptan or hydrogen sulfide,
A gas sensitive layer and an electrode for detecting the electrical resistance of the gas sensitive layer;
The gas sensitive layer contains titanium oxide and / or cerium oxide and vanadium oxide , the content of titanium oxide and / or cerium oxide is 50 mass% or more and 99 mass% or less, and the content of vanadium oxide is 1 A gas sensor having a mass% of 15% or less. The gas sensor according to claim 5, wherein the gas sensitive layer further contains tungsten oxide, and the content of tungsten oxide is 49 mass% or less. The gas sensor according to claim 5 or 6 , further comprising heating means for heating the gas sensitive layer by resistance heating.

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