JPH01145561A - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JPH01145561A JPH01145561A JP30410087A JP30410087A JPH01145561A JP H01145561 A JPH01145561 A JP H01145561A JP 30410087 A JP30410087 A JP 30410087A JP 30410087 A JP30410087 A JP 30410087A JP H01145561 A JPH01145561 A JP H01145561A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- alumina
- catalyst layer
- platinum
- sensitive body
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 58
- 239000003054 catalyst Substances 0.000 claims abstract description 51
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 28
- 239000010949 copper Substances 0.000 claims abstract description 18
- 229910052802 copper Inorganic materials 0.000 claims abstract description 15
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 10
- 230000003647 oxidation Effects 0.000 claims description 38
- 238000007254 oxidation reaction Methods 0.000 claims description 38
- 239000004065 semiconductor Substances 0.000 claims description 12
- 229910044991 metal oxide Inorganic materials 0.000 claims description 10
- 150000004706 metal oxides Chemical class 0.000 claims description 10
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 239000007789 gas Substances 0.000 abstract description 79
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 abstract description 45
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 abstract description 36
- 235000019441 ethanol Nutrition 0.000 abstract description 23
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 21
- 239000001282 iso-butane Substances 0.000 abstract description 18
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 abstract description 11
- 229910001887 tin oxide Inorganic materials 0.000 abstract description 11
- 238000002156 mixing Methods 0.000 abstract description 5
- 239000000843 powder Substances 0.000 abstract description 5
- 239000000758 substrate Substances 0.000 abstract description 5
- 230000001590 oxidative effect Effects 0.000 abstract description 4
- 229910000881 Cu alloy Inorganic materials 0.000 abstract description 2
- 229910001260 Pt alloy Inorganic materials 0.000 abstract description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 abstract description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 2
- 238000010891 electric arc Methods 0.000 abstract description 2
- 239000001301 oxygen Substances 0.000 abstract description 2
- 229910052760 oxygen Inorganic materials 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 abstract 1
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 abstract 1
- 238000000354 decomposition reaction Methods 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 abstract 1
- 230000035945 sensitivity Effects 0.000 description 20
- 239000003915 liquefied petroleum gas Substances 0.000 description 17
- 230000000694 effects Effects 0.000 description 6
- 238000000034 method Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は金属酸化物半導体をガス感応体とするガスセ
ンサに係わり、特に金属酸化物半導体の表面に設けられ
た酸化触媒層に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas sensor using a metal oxide semiconductor as a gas sensor, and particularly to an oxidation catalyst layer provided on the surface of the metal oxide semiconductor.
酸化スズのような金属酸化物半導体はその電気抵抗値が
可燃性ガスによって変化するので、この現象を利用して
ガスの検出を行うことができる。Since the electrical resistance of a metal oxide semiconductor such as tin oxide changes depending on flammable gas, gas can be detected using this phenomenon.
ところがこのような電気抵抗の変化はガスに対する選択
性がない。例えばＬＰＧ （液化石油ガス）用ガス漏れ
警報器においてはＬＰＧにより警報を発する他、エチル
アルコールガスによっても警報を発する。このような誤
報を防止するために金属酸化物半導体のガス感応体また
はその表面にエチルアルコールに対する不活性処理が施
される。このうち後者の処理に相当するものとしてガス
感応体の表面に白金を担持したアルミナ粉末を塗布して
酸化触媒層を設けるものが特公昭６１−３７５７７号公
報や表面科学第５巻特集号Ｐ２４１（１９８４）に開示
されている。第３図は特公昭６１−３７５７７号公報に
記載されたこのようなセンサの１例で、１１はガス感応
体としての半導体、１２．１３は電極、１４は酸化触媒
層に埋め込まれたヒータ、１５は白金等を担持した白金
族触媒という酸化触媒層である。このセンサはヒータ１
４で加熱され、エチルアルコールは酸化触媒層によって
選択的に酸化されて二酸化炭素となるのでエチルアルコ
ールはガス感応体には到達することができず、センサは
エチルアルコールに対しては応答しなくなる。これに対
しＬＰＧは酸化触媒層によっては酸化されないので酸化
触媒層を通り抜けてガス感応体に到達し、ガス感応体で
ある金属酸化物半導体の電気抵抗を変化させる。このよ
うにしてエチルアルコールによる誤報を防止してＬＰＧ
にのみ応答するセンサが得られる。However, such a change in electrical resistance has no selectivity to gas. For example, in a gas leak alarm for LPG (liquefied petroleum gas), in addition to issuing an alarm using LPG, it also issues an alarm using ethyl alcohol gas. In order to prevent such false alarms, the metal oxide semiconductor gas sensitive body or its surface is subjected to an inert treatment against ethyl alcohol. Among these, methods corresponding to the latter treatment, in which an oxidation catalyst layer is provided by applying platinum-supported alumina powder to the surface of the gas sensitive body, are reported in Japanese Patent Publication No. 37577/1982 and Surface Science Vol. 5 Special Issue P241 ( 1984). FIG. 3 shows an example of such a sensor described in Japanese Patent Publication No. 61-37577, in which 11 is a semiconductor as a gas sensitive body, 12 and 13 are electrodes, 14 is a heater embedded in the oxidation catalyst layer, 15 is an oxidation catalyst layer called a platinum group catalyst supporting platinum or the like. This sensor is heater 1
4, the ethyl alcohol is selectively oxidized to carbon dioxide by the oxidation catalyst layer, so that the ethyl alcohol cannot reach the gas sensitive body, and the sensor no longer responds to ethyl alcohol. On the other hand, since LPG is not oxidized by the oxidation catalyst layer, it passes through the oxidation catalyst layer and reaches the gas sensitive body, changing the electrical resistance of the metal oxide semiconductor that is the gas sensitive body. In this way, false alarms caused by ethyl alcohol can be prevented and LPG
This results in a sensor that responds only to
ところが上記のような酸化触媒層の選択性は温度が低い
場合に成立するものであるが、センサの温度が高くなる
と選択性が悪くなる。第４図にこの関係が表示されてい
る。この図でガス感度（Ｒ。However, although the selectivity of the oxidation catalyst layer as described above is achieved when the temperature is low, the selectivity deteriorates as the temperature of the sensor increases. This relationship is displayed in FIG. In this figure, gas sensitivity (R.
／Ｒｇ） は空気中におけるガス感応体１１の電気抵
抗Ｒｏ と可燃性ガス中におけるガス感応体１１の電気
抵抗Ｒｇ との比である。ＬＰＧやエチルアルコールの
ような可燃性ガス中での電気抵抗Ｒｇ は空気中での電
気抵抗ＲＯに比し小さくなるので可燃性ガス中ではガス
感度（Ｒｏ／Ｒｇ） は一般に１０以上の値を示す。/Rg) is the ratio of the electrical resistance Ro of the gas sensitive body 11 in air to the electrical resistance Rg of the gas sensitive body 11 in combustible gas. The electrical resistance Rg in flammable gases such as LPG and ethyl alcohol is smaller than the electrical resistance RO in air, so gas sensitivity (Ro/Rg) generally shows a value of 10 or more in flammable gases. .
従ってガスセンサは酸化触媒層１５によって可燃性ガス
が酸化されないときはガスセンサのガス感度は１０以上
の値となり、酸化されるときは１０以下の小さな値を示
すことになる。第４図で曲線３３はＬＰＧの主成分であ
るイソブタンに対するガス感度（濃度０．２％） を示
し、曲線３４はエチルアルコールに対するガス感度（濃
度０．２％）を示す。曲線３３からＬＰＧは温度４００
℃までは酸化触媒層によって酸化されないこと、温度４
００℃を越えると酸化触媒層による酸化がはじまり徐々
にガス感応体１１に到達するＬＰＧが減少してゆき、温
度４５０℃においてはＬＰＧは殆ど酸化触媒層によって
酸化され、ガス感応体に到達するものは皆無に近くなる
ことがわかる。、これに対し曲線３４からはエチルアル
コールは温度３５０℃〜４５０℃の範囲で酸化触媒層に
よって酸化され、ガス感応体１１には到達するものが殆
どないことがわかる。以上のようにして白金を担持した
酸化触媒層を備えるガスセンサは、ガスセンサ温度が４
２５℃以下のときはＬＰＧに対しガス感度が１０以上と
なりＬＰＧに対しエチルアルコールによる誤報なしに警
報を発することができるが、４５０℃に近くなると、Ｌ
ＰＧに対するガス感度が１０以下となりＬＰＧに対して
応答しなくなるという問題点を生ずる。Therefore, when the combustible gas is not oxidized by the oxidation catalyst layer 15, the gas sensitivity of the gas sensor takes a value of 10 or more, and when it is oxidized, it shows a small value of 10 or less. In FIG. 4, curve 33 shows the gas sensitivity to isobutane (concentration 0.2%), which is the main component of LPG, and curve 34 shows the gas sensitivity to ethyl alcohol (concentration 0.2%). From curve 33, LPG has a temperature of 400
It is not oxidized by the oxidation catalyst layer up to a temperature of 4°C.
When the temperature exceeds 00°C, oxidation by the oxidation catalyst layer begins, and the amount of LPG that reaches the gas sensitive body 11 gradually decreases, and at a temperature of 450°C, most of the LPG is oxidized by the oxidation catalyst layer and reaches the gas sensitive body. It can be seen that there are almost no cases. On the other hand, it can be seen from curve 34 that ethyl alcohol is oxidized by the oxidation catalyst layer in the temperature range of 350° C. to 450° C., and almost no amount reaches the gas sensitive body 11. The gas sensor equipped with the oxidation catalyst layer supporting platinum as described above has a gas sensor temperature of 4.
When the temperature is below 25℃, the gas sensitivity for LPG is 10 or more, and it is possible to issue an alarm for LPG without false alarms due to ethyl alcohol, but when the temperature approaches 450℃,
A problem arises in that the gas sensitivity to PG is less than 10 and there is no response to LPG.
この発明は上述の点に鑑みてなされ、その目的は酸化触
媒層に担持される触媒を改良することによりアルコール
には応答しないが広い温度範囲でＬＰＧの主成分である
イソブタンに対して応答できるガスセンサを提供するこ
とにある。This invention was made in view of the above points, and its purpose is to create a gas sensor that does not respond to alcohol but can respond to isobutane, the main component of LPG, over a wide temperature range by improving the catalyst supported on the oxidation catalyst layer. Our goal is to provide the following.
上記の目的はこの発明によれば金属酸化物半導・体をガ
ス感応体４として用いるガスセンサにおいて、前記ガス
感応体４の外部表面に白金と銅の合金触媒を担持させた
酸化触媒層５を備えることにより達成される。According to the present invention, the above object is to provide a gas sensor using a metal oxide semiconductor/body as a gas sensitive body 4, in which an oxidation catalyst layer 5 in which an alloy catalyst of platinum and copper is supported on the external surface of the gas sensitive body 4 is provided. This is achieved by being prepared.
ガス感応体４としては酸化スズのような可燃性ガスに応
答可能な金属酸化物半導体が用いられる。As the gas sensitive body 4, a metal oxide semiconductor capable of responding to a combustible gas such as tin oxide is used.
酸化触媒層５はアルミナのような触媒担体上に白金と銅
の合金触媒を担持して形成される。白金と銅は触媒担体
に対しそれぞれ０．２重量％〜４重量％、１重量％〜１
０重量％になるように担持される。The oxidation catalyst layer 5 is formed by supporting an alloy catalyst of platinum and copper on a catalyst carrier such as alumina. Platinum and copper are 0.2% to 4% by weight and 1% to 1% by weight, respectively, based on the catalyst carrier.
It is supported at 0% by weight.
銅と白金は重量比で０．２５〜５０の範囲にされる。酸
化触媒層はＬＰＧの主成分であるイソブタンを酸化燃焼
させることがないのでイソブタンは酸化触媒層を通り抜
けて金属酸化物半導体からなるガス感応体に到達するの
でガス感応体はＬＰＧに応答する。これに対しエチルア
ルコールは酸化触媒層によって酸化燃焼されるのでガス
感応体に到達することができない。そのためにガス感応
体はエチルアルコールに応答しない。The weight ratio of copper and platinum is in the range of 0.25 to 50. Since the oxidation catalyst layer does not oxidize and burn isobutane, which is the main component of LPG, the isobutane passes through the oxidation catalyst layer and reaches the gas sensitive body made of a metal oxide semiconductor, so that the gas sensitive body responds to LPG. On the other hand, ethyl alcohol cannot reach the gas sensitive body because it is oxidized and burned by the oxidation catalyst layer. Therefore, the gas sensitizer does not respond to ethyl alcohol.
白金と銅の合金触媒を担持させた酸化触媒層は温度３５
０℃〜４５０℃の範囲においてエチルアルコールを酸化
燃焼させる。しかしＬＰＧの成分であるイソブタンにつ
いては上記温度範囲でこれを酸化燃焼させることがない
。The oxidation catalyst layer supporting the platinum and copper alloy catalyst has a temperature of 35
Ethyl alcohol is oxidized and burned in the range of 0°C to 450°C. However, isobutane, which is a component of LPG, is not oxidized and burned within the above temperature range.
次にこの発明の実施例を図面に基づいて説明する。第１
図はこの発明の実施例に係わるガスセンサの部分断面図
であり、１はアルミナ基板、２は白金ヒータ、３Ａ、３
Ｂは白金電極、４は酸化スズ半導体からなるガス感応体
、５は酸化触媒層、６Ａ、６Ｂは電極用引出線、？Ａ、
７Ｂはヒータ用引出線である。Next, embodiments of the present invention will be described based on the drawings. 1st
The figure is a partial sectional view of a gas sensor according to an embodiment of the present invention, in which 1 is an alumina substrate, 2 is a platinum heater, 3A, 3
B is a platinum electrode, 4 is a gas sensitive body made of a tin oxide semiconductor, 5 is an oxidation catalyst layer, 6A and 6B are electrode lead wires, ? A,
7B is a leader wire for the heater.
このガスセンサは次のようにして製造される。This gas sensor is manufactured as follows.
まず、アルミナ基板に白金電極と白金ヒータを焼き付け
、白金電極側表面にスズ蒸気と酸素をアーり放電を用い
て反応させて生成した酸化スズ層を形成する。この酸化
スズ層がガス感応体となる。First, a platinum electrode and a platinum heater are baked on an alumina substrate, and a tin oxide layer is formed on the surface of the platinum electrode by reacting tin vapor and oxygen using an arc discharge. This tin oxide layer becomes a gas sensitive body.
酸化スズ層の形成は他の方法、例えば、酸化スズ粉末を
バインダーなどと混合してペースト状にして塗布し、焼
結させる方法で行ってもよい。The tin oxide layer may be formed by other methods, such as a method in which tin oxide powder is mixed with a binder and the like, applied in the form of a paste, and then sintered.
酸化触媒層は次のようにしてつくられる。アルミナ粉末
とコロイダルアルミナを混合したアルミナペーストで酸
化スズ層を被覆し、乾燥後５５０℃で３時間焼成して厚
さ０．３ｍｍのアルミナ層を形成する。The oxidation catalyst layer is made as follows. The tin oxide layer is coated with an alumina paste made by mixing alumina powder and colloidal alumina, and after drying, it is fired at 550° C. for 3 hours to form an alumina layer with a thickness of 0.3 mm.
酸化スズ層の上にアルミナ層を形成させたアルミナ基板
を塩化白金酸（Ｈ２ＰｔＣＡ’ｓ）水溶液と硝酸鋼（Ｃ
ｕ （ＮＯ３） ２ ）水溶液とを混合して所定濃度に
調製した混合水溶液中に３０分間浸漬した後乾燥させ、
空気中６００℃で３時間加熱分解して白金（ｐｔ）と銅
（Ｃｕ）が合金化してアルミナに担持された酸化触媒層
を得る。An alumina substrate with an alumina layer formed on a tin oxide layer is heated with an aqueous solution of chloroplatinic acid (H2PtCA's) and nitric acid steel (C
u (NO3) 2) aqueous solution to a predetermined concentration, immersed in the mixed aqueous solution for 30 minutes, and then dried.
Platinum (PT) and copper (Cu) are alloyed by thermal decomposition in air at 600° C. for 3 hours to obtain an oxidation catalyst layer supported on alumina.
比較例として、ｐｔのみを担持した酸化触媒層は、塩化
白金酸水溶液を用いて上記と同様な工程で得られる。As a comparative example, an oxidation catalyst layer supporting only PT was obtained in the same process as above using an aqueous chloroplatinic acid solution.
本実施例では、アルミナ層を形成させた後、ｐｔとＣｕ
とを担持させたが、あらかじめｐｔとＣｕとを混合して
担持させたアルミナ粉末をコロイダルアルミナと混合し
て酸化スズ層を被覆して、酸化触媒層を形成させても同
様な効果が得られる。In this example, after forming an alumina layer, pt and Cu
However, the same effect can also be obtained by forming an oxidation catalyst layer by mixing colloidal alumina with alumina powder that has been supported by mixing PT and Cu in advance and covering it with a tin oxide layer. .
このようにして、酸化触媒層を形成した後、電極用引出
線（白金線）６Ａ、６Ｂとヒータ用引出線（白金線）７
Ａ、７Ｂをそれぞれ白金電極３Ａ。After forming the oxidation catalyst layer in this way, the electrode lead wires (platinum wire) 6A, 6B and the heater lead wire (platinum wire) 7
A and 7B are platinum electrodes 3A, respectively.
３Ｂとヒータ両端にスポット溶接する。Spot weld 3B to both ends of the heater.
このようにして得られたガスセンサの空気中での電気抵
抗をＲＯ％０．２％イソブタン中、または０．２％エチ
ルアルコールガス中での電気抵抗をＲｇとして、Ｒｏ／
Ｒｇをガス感度とした。ガスセンサの温度は、赤外線放
射温度計で測定し、ヒータ印加電圧を調節して３５０℃
、４００℃、４５０℃とした。The electrical resistance of the gas sensor thus obtained in air is RO%, and the electrical resistance in 0.2% isobutane or 0.2% ethyl alcohol gas is Rg, and Ro/
Rg was defined as gas sensitivity. The temperature of the gas sensor is measured with an infrared radiation thermometer and adjusted to 350°C by adjusting the voltage applied to the heater.
, 400°C, and 450°C.
第２図には、本発明に係わるガスセンサのガス感度の温
度依存性を示す。FIG. 2 shows the temperature dependence of the gas sensitivity of the gas sensor according to the present invention.
曲線３１は０．２％イソブタンのガス感度（Ｒｏ／Ｒｇ
）であり、曲線３２は０．２％エチルアルコールガスの
ガス感度である。Curve 31 shows the gas sensitivity of 0.2% isobutane (Ro/Rg
), and curve 32 is the gas sensitivity of 0.2% ethyl alcohol gas.
第２図と第４図から明らかなように、エチルアルコール
ガス感度を低減する効果は、ＰｔとＣｕを混合し合金化
して用いた場合と、ｐｔのみを用いた場合とでは大きな
差はない。しかし、ｐｔのみを酸化触媒層としたガスセ
ンサでは、温度が高くなるとイソブタン感度が急に低下
する。これに対してＰｔとＣｕを合金化して担持させた
酸化触媒層を被覆したガスセンサは、温度が高くなって
もイソブタン感度はほとんど変化せず一定である。この
ような効果は、ＰｔとＣｕの担持重量比で０．２５〜５
０の範囲でｇ忍められる。As is clear from FIGS. 2 and 4, there is no significant difference in the effect of reducing ethyl alcohol gas sensitivity between the case where a mixture of Pt and Cu is used as an alloy, and the case where only PT is used. However, in a gas sensor having only PT as an oxidation catalyst layer, the isobutane sensitivity suddenly decreases as the temperature increases. On the other hand, in a gas sensor coated with an oxidation catalyst layer in which an alloy of Pt and Cu is supported, the isobutane sensitivity hardly changes and remains constant even when the temperature increases. Such an effect is obtained when the supported weight ratio of Pt and Cu is 0.25 to 5.
g can be tolerated within the range of 0.
また担持量は、ｐｔが０．２重量％〜４重量％、Ｃｕが
１重量％〜１０重量％の範囲でその効果が認められる。Moreover, the effect is recognized when the supported amount is in the range of 0.2% to 4% by weight of PT and 1% to 10% by weight of Cu.
担持量が小さいとエチルアルコール感度が大きくなり、
担持量が大きいとイソブタン感度が小さくなるので好ま
しくない。When the loading amount is small, the ethyl alcohol sensitivity increases,
If the supported amount is large, the sensitivity to isobutane becomes low, which is not preferable.
このように、本発明においてＰｔとＣｕを合金化させた
触媒をアルミナ担体に担持させた酸化触媒層を用いたガ
スセンサのイソブタンガス感−度が温度に依存しないで
一定である原因は明らかではないが、エチルアルコール
に対して酸化活性が高く、イソブタンに対して不活性で
ある銅がＰｔの作用を修正し協同して働くためと考えら
れる。As described above, it is not clear why the isobutane gas sensitivity of the gas sensor using the oxidation catalyst layer in which a catalyst alloyed with Pt and Cu is supported on an alumina carrier is constant regardless of temperature in the present invention. However, this is thought to be because copper, which has a high oxidizing activity against ethyl alcohol and is inactive against isobutane, modifies the action of Pt and works in cooperation with it.
このようにして、ガスセンサの広い温度範囲（３５０℃
〜４５０℃）において、エチルアルコールには応答せず
、イソブタンに応答するガスセンサが得られる。またこ
の発明に係わる酸化触媒層は一酸化炭素（ＣＯ）やメチ
ルアルコール等に対しても上記温度範囲で酸化作用を有
するので、この発明に係わる酸化触媒層を備えるガスセ
ンサはイソブタンに対する選択性に優れるということが
できる。In this way, the wide temperature range of the gas sensor (350°C
~450° C.), a gas sensor is obtained that does not respond to ethyl alcohol but responds to isobutane. Furthermore, since the oxidation catalyst layer according to the present invention has an oxidizing effect on carbon monoxide (CO), methyl alcohol, etc. in the above temperature range, the gas sensor equipped with the oxidation catalyst layer according to the present invention has excellent selectivity to isobutane. It can be said that.
さらに、この発明に係わる酸化触媒層は広い温度範囲で
イソブタンに対するガス感度が高くかつ安定なので、こ
れを用いたガスセンサの出力は温度変化の影響を受けに
＜＜、信頼性に優れるということができ、さらにまたセ
ンサ温度の適用範囲が広がってガスセンサの応用性の幅
が広がるという効果もあわせ得られる。Furthermore, since the oxidation catalyst layer according to the present invention has high gas sensitivity to isobutane and is stable over a wide temperature range, the output of a gas sensor using this layer is not affected by temperature changes and can be said to be highly reliable. Furthermore, the applicable range of the sensor temperature is expanded, and the range of applicability of the gas sensor is also expanded.
この発明によれば金属酸化物半導体をガス感応体として
用いるガスセンサにおいて、前記感応体の外部表面に白
金と銅の合金触媒を担持させた酸化触媒層を備えるので
、この酸化触媒層が広い温度範囲でエチルアルコールを
酸化燃焼させるが、イソブタンは酸化燃焼させることが
ないという作用を示す結果、広い温度範囲でエチルアル
コールには応答しないで、イソブタンに応答するガスセ
ンサを得ることができる。According to this invention, in a gas sensor using a metal oxide semiconductor as a gas sensitive body, an oxidation catalyst layer in which an alloy catalyst of platinum and copper is supported is provided on the external surface of the sensitive body, so that this oxidation catalyst layer has a wide temperature range. As a result, it is possible to obtain a gas sensor that does not respond to ethyl alcohol but responds to isobutane over a wide temperature range.
第１図はこの発明の実施例に係わるガスセンサの部分断
面図、第２図はこの発明の実施例に係わるガスセンサの
ガス感度特性図、第３図は従来のガスセンサの構成図、
第４図は従来のガスセンサのガス感度特性図である。
４ ガス感応体、５ 酸化触媒層。
第１図
第２図
第３図
Ｌンサ温度（°Ｃ）
第４図FIG. 1 is a partial sectional view of a gas sensor according to an embodiment of the present invention, FIG. 2 is a gas sensitivity characteristic diagram of a gas sensor according to an embodiment of the present invention, and FIG. 3 is a configuration diagram of a conventional gas sensor.
FIG. 4 is a gas sensitivity characteristic diagram of a conventional gas sensor. 4 gas sensitive body, 5 oxidation catalyst layer. Figure 1 Figure 2 Figure 3 L sensor temperature (°C) Figure 4
Claims (1)
ンサにおいて、前記ガス感応体の外部表面に白金と銅の
合金触媒を担持させた酸化触媒層を備えることを特徴と
するガスセンサ。1) A gas sensor using a metal oxide semiconductor as a gas sensor, characterized in that the gas sensor has an oxidation catalyst layer supporting an alloy catalyst of platinum and copper on the outer surface of the gas sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30410087A JPH01145561A (en) | 1987-12-01 | 1987-12-01 | Gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30410087A JPH01145561A (en) | 1987-12-01 | 1987-12-01 | Gas sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01145561A true JPH01145561A (en) | 1989-06-07 |
Family
ID=17929026
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30410087A Pending JPH01145561A (en) | 1987-12-01 | 1987-12-01 | Gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01145561A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0703449A1 (en) * | 1994-09-23 | 1996-03-27 | Ford Motor Company Limited | Catalytic calorimetric gas sensor |
-
1987
- 1987-12-01 JP JP30410087A patent/JPH01145561A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0703449A1 (en) * | 1994-09-23 | 1996-03-27 | Ford Motor Company Limited | Catalytic calorimetric gas sensor |
| US5813764A (en) * | 1994-09-23 | 1998-09-29 | Ford Global Technologies, Inc. | Catalytic differential calorimetric gas sensor |
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