JPS6122776B2 - - Google Patents
Info
- Publication number
- JPS6122776B2 JPS6122776B2 JP53052368A JP5236878A JPS6122776B2 JP S6122776 B2 JPS6122776 B2 JP S6122776B2 JP 53052368 A JP53052368 A JP 53052368A JP 5236878 A JP5236878 A JP 5236878A JP S6122776 B2 JPS6122776 B2 JP S6122776B2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- sensitive
- sensitivity
- present
- catalyst layer
- 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.)
- Expired
Links
- 239000003054 catalyst Substances 0.000 claims description 21
- 239000004065 semiconductor Substances 0.000 claims description 14
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 5
- 229910001887 tin oxide Inorganic materials 0.000 claims description 5
- 239000007789 gas Substances 0.000 description 64
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 24
- 230000035945 sensitivity Effects 0.000 description 22
- 239000001282 iso-butane Substances 0.000 description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 10
- 235000019441 ethanol Nutrition 0.000 description 9
- 229910004298 SiO 2 Inorganic materials 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 229910006404 SnO 2 Inorganic materials 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Description
本発明は、選択性に優れた感ガス素子に関す
る。
酸化物半導体表面にガスが接触すると、酸化物
半導体の表面の比抵抗が変化することを利用した
感ガス素子が知られている。例えば、Ｎ型半導性
を示すZnO，SnO2，Fe2O3等に還元性ガスが接触
すると抵抗値は減少し、また酸化性ガスが接触す
ると、抵抗値は増加する。またＰ型半導体を示す
酸化物半導体においては抵抗値の増減が逆の関係
を示す。上記のごとき酸化物半導体において、各
種ガスとの反応性すなわち選択性は、半導体表面
温度、表面電子レベルの構造、気孔率および気孔
の大きさ等により決まるが、一般には酸化物半導
体のみでは感ガス素子として感度が小さく、選択
性も十分とは言えない。そこで酸化物半導体に
Pt，Pbなどの触媒を添加含有せしめ感度を上げ
る事が試みられている。この場合、素子温度を選
択することにより、ある程度の選択性を得ること
ができる。例えばPtをガス感応体に添加したもの
では、イソブタンガスに対しては感度が高く、水
素ガス、一酸化炭素ガスに対してはあまり反応し
ない。一方Pdを添加した場合には、イソブタン
ガス、水素ガス、一酸化炭素ガスに対して共に大
きな感度を示す。しかしながら両者ともエチルア
ルコールガスなどのアルコールガスなどのアルコ
ール系ガスに対しても大きな感度を示す。従つて
上記の如き素子においては、特に一般家庭では、
食物、整髪料、化粧品などにより発生するアルコ
ール系ガスに対しても、LPGガスと同様に感応し
実用上大きな問題点となつていた。
本発明は上記の点に鑑みアルコール系ガスに対
して感応することなくイソブタンガスに対して高
い感度を有する信頼性の高いLPG用感ガス素子を
提供することを目的とする。本発明は、SiO2，
Ａ2O3等の触媒担体に対し0.005〜８重量％のPt
と、モル比で、前記Ptの1.5〜30倍のＰとを含む
触媒層を酸化錫系半導体からなるガス感応体表面
に設けた感ガス素子である。
なお本発明においてPtの添加量を0.005〜８重
量％としたのは、0.005重量％未満では、イソブ
タンガスに対する感度が小さくなり、また８重量
％を越えるとアルコールガスに対しても感応し易
くなるためである。
またＰの添加量をPtの添加量に対しモル比で
1.5〜30倍としたのは、1.5倍未満では、イソブタ
ンガスに対する感度とアルコール系ガスに対する
感度とに顕著な差が表れずイソブタンガスに対す
る感度も小さくなり、また30倍を越えるイソブタ
ンガスなどのLPGに対する感度が小さくなるため
である。
以下本発明を構造例により詳細に説明する。ま
ず本発明に係る感ガス素子は例えば第１図に断面
的に示すごとく、筒状絶縁基体１外周面に一対の
電極２を有し、前記筒状絶縁基体１および電極２
を被覆するように酸化錫系半導体からなるガス感
応体３が設けられている。さらに前記ガス感応体
３表面には所定量のPtおよびＰを含むシリカ・ア
ルミナからなる触媒層４が設けられている。また
前記のように構成された感ガス素子はは例えば第
２図に斜視的に示す如くピン足上に組立てられ
る。なお、第２図中５はリード線を６は絶縁板７
はヒーターを示す。ヒーター７はガス感応体の感
度を向上させるために設けられたものであり、必
要に応じ適宜設けることができる。なお触媒層４
はガス感応体３表面を必ずしも全面的に被覆して
いなくともよい。
また上記においては触媒層の担体としてシリ
カ・アルミナを用いたが、他に適宜選択してもよ
く、さらに担体を用いない場合も同様の効果が得
られる。
本発明に係る感ガス素子は例えば以下の如く製
造される。例えば酸化錫系半導体としてSnO2―
SiO2系を用いる場合、SnO2およびSiO2粉末を所
定組成比で秤取し、混合したのち水またはバイン
ダーを加えペースト状とし、第１図に示すごとく
一対の電極２を設けた絶縁基板１に塗布し乾燥後
300〜1100℃で焼成しガス感応体を形成する。
一方、触媒層は例えばH2Ptc６・6H2Oと
H3PO4，NH4H2PO4を加えて適当なPHの水溶液
を作り、本発明の組成範囲内となるように混合
し、これを担体としてのシリカ・アルミナ粉末を
加え泥漿とする。この泥漿をよく混合、乾燥した
後、300℃〜1000℃で焼成し、粉砕し微粉末とす
る。この微粉末に水と適当なバインダーを加えペ
ースト状とした後、前記ガス感応体表面に塗布、
乾燥し300〜1000℃で焼成して本発明にる感ガス
素子が得られる。この触媒層はガス感応体層と同
程度の厚みであり、通常100μｍ前後である。な
お触媒層は担体表面にPt，Ｐが担持された形とな
り、体積のほとんどはＡ2O3，SiO2等の担体で
ある。
なおこの実施例ではSiO2／Ａ2O3が５程度
（重量比）であるが、SiO2，Ａ2O3等の単体で
も良い。
次に、上記の如き本発明に係る感ガス素子の諸
特性を測定し、第３図および第４図に示す。第３
図は本発明に係る感ガス素子におけるPtおよびＰ
の添加量に対する0.2Vol％のイソブタンガスに対
する感度を示す。なお感度は空気中における抵抗
値Roとガス中における抵抗値Rgとの比をRo/Rg
として示したものであり、その値が大きい程ガス
検出が容易である。また第４図は0.2Vol％のアル
コールガスに対する感度Ro/Rgを示す。なお第３
図、第４図の特性は素子温度350℃での値であ
る。
第３図および第４図から明らかな如く触媒層に
おけるPt，Ｐの添加量が本発明範囲内ではイソブ
タンガスに対し優れた感度を示し、アルコールガ
スには、ほとんど感心しない。
次に触媒を用いない場合、Ｐのみを含む触媒層
を用いた場合、Ptのみを含む触媒層を用いた場合
および本発明の如く、ＰおよびPtを含む触媒層を
用いた場合の感ガス素子について、0.2Vol％の各
種ガスに対する感度Ro/Rgを測定し第１表に示
す。
The present invention relates to a gas-sensitive element with excellent selectivity. Gas-sensitive elements are known that utilize the fact that the specific resistance of the surface of an oxide semiconductor changes when gas comes into contact with the surface of the oxide semiconductor. For example, when a reducing gas comes into contact with ZnO, SnO 2 , Fe 2 O 3 , etc., which exhibit N-type semiconductivity, the resistance value decreases, and when an oxidizing gas comes into contact with it, the resistance value increases. Further, in an oxide semiconductor that is a P-type semiconductor, the increase and decrease in resistance value exhibits an inverse relationship. The reactivity, or selectivity, of the oxide semiconductors mentioned above with various gases is determined by the semiconductor surface temperature, surface electron level structure, porosity, pore size, etc., but in general, oxide semiconductors alone are sensitive to gases. As an element, the sensitivity is low and the selectivity is not sufficient. Therefore, oxide semiconductor
Attempts have been made to increase sensitivity by adding catalysts such as Pt and Pb. In this case, a certain degree of selectivity can be obtained by selecting the element temperature. For example, a gas sensitive material in which Pt is added has high sensitivity to isobutane gas, but does not react much to hydrogen gas or carbon monoxide gas. On the other hand, when Pd is added, it exhibits high sensitivity to isobutane gas, hydrogen gas, and carbon monoxide gas. However, both exhibit high sensitivity to alcohol-based gases such as ethyl alcohol gas. Therefore, in the above-mentioned devices, especially in ordinary homes,
In the same way as LPG gas, it is sensitive to alcohol-based gases emitted by foods, hair products, cosmetics, etc., which has become a major problem in practical use. In view of the above points, it is an object of the present invention to provide a highly reliable gas-sensitive element for LPG that has high sensitivity to isobutane gas without being sensitive to alcohol-based gas. The present invention provides SiO 2 ,
0.005 to 8% by weight of Pt based on catalyst support such as A 2 O 3
This is a gas-sensitive element in which a catalyst layer containing P in a molar ratio of 1.5 to 30 times that of Pt is provided on the surface of a gas-sensitive body made of a tin oxide semiconductor. In addition, in the present invention, the amount of Pt added is set to 0.005 to 8% by weight, because if it is less than 0.005% by weight, the sensitivity to isobutane gas will be small, and if it exceeds 8% by weight, it will become sensitive to alcohol gas. It's for a reason. Also, the amount of P added is expressed as a molar ratio to the amount of Pt added.
The reason why the ratio is 1.5 to 30 times is that if the ratio is less than 1.5 times, there will be no noticeable difference between the sensitivity to isobutane gas and the sensitivity to alcohol-based gases, and the sensitivity to isobutane gas will also be small. This is because the sensitivity to The present invention will be explained in detail below using structural examples. First, the gas-sensitive element according to the present invention has a pair of electrodes 2 on the outer peripheral surface of a cylindrical insulating base 1, as shown in cross section in FIG.
A gas sensitive body 3 made of a tin oxide semiconductor is provided so as to cover the gas sensitive body 3 . Furthermore, a catalyst layer 4 made of silica/alumina containing predetermined amounts of Pt and P is provided on the surface of the gas sensitive body 3. Further, the gas-sensitive element constructed as described above is assembled on a pin leg, for example, as shown perspectively in FIG. In addition, in Fig. 2, 5 is a lead wire, and 6 is an insulating plate 7.
indicates a heater. The heater 7 is provided to improve the sensitivity of the gas sensitive element, and can be provided as appropriate if necessary. Note that the catalyst layer 4
does not necessarily have to cover the entire surface of the gas sensitive body 3. Further, in the above, silica/alumina is used as a carrier for the catalyst layer, but other materials may be selected as appropriate, and the same effect can be obtained even when no carrier is used. The gas-sensitive element according to the present invention is manufactured, for example, as follows. For example, SnO 2 - as a tin oxide semiconductor
When using the SiO 2 system, SnO 2 and SiO 2 powder are weighed out at a predetermined composition ratio, mixed, and then water or a binder is added to form a paste, and an insulating substrate 1 on which a pair of electrodes 2 are provided as shown in FIG. After applying and drying
It is fired at 300-1100℃ to form a gas sensitive body. On the other hand, the catalyst layer is made of, for example, H 2 Ptc 6.6H 2 O.
H 3 PO 4 and NH 4 H 2 PO 4 are added to prepare an aqueous solution with a suitable pH, and mixed so that the composition falls within the composition range of the present invention, and silica/alumina powder as a carrier is added to this to form a slurry. After thoroughly mixing and drying this slurry, it is calcined at 300°C to 1000°C and ground into a fine powder. After adding water and a suitable binder to this fine powder and making it into a paste, it is applied to the surface of the gas sensitive body.
The gas-sensitive element according to the present invention is obtained by drying and firing at 300 to 1000°C. This catalyst layer has a thickness comparable to that of the gas sensitive layer, and is usually around 100 μm. Note that the catalyst layer has a form in which Pt and P are supported on the surface of the carrier, and most of the volume is made up of carriers such as A 2 O 3 and SiO 2 . In this embodiment, the SiO 2 /A 2 O 3 ratio is about 5 (weight ratio), but a single substance such as SiO 2 or A 2 O 3 may also be used. Next, various characteristics of the gas-sensitive element according to the present invention as described above were measured and are shown in FIGS. 3 and 4. Third
The figure shows Pt and Pt in the gas-sensitive element according to the present invention.
The sensitivity to 0.2Vol% isobutane gas with respect to the addition amount of is shown. Sensitivity is the ratio of the resistance Ro in air to the resistance Rg in gas as Ro/Rg.
The larger the value, the easier the gas detection. Furthermore, Figure 4 shows the sensitivity Ro/Rg to 0.2 Vol% alcohol gas. Furthermore, the third
The characteristics shown in Fig. 4 are values at an element temperature of 350°C. As is clear from FIGS. 3 and 4, when the amounts of Pt and P added in the catalyst layer are within the range of the present invention, the catalyst exhibits excellent sensitivity to isobutane gas and is hardly sensitive to alcohol gas. Next, a gas-sensitive element in which no catalyst is used, a catalyst layer containing only P, a catalyst layer containing only Pt, and a catalyst layer containing P and Pt as in the present invention. The sensitivity Ro/Rg for various gases at 0.2 Vol% was measured and shown in Table 1.
【表】
この結果第１表から明らかな如く、無触媒の場
合、全搬的に感度が低くイソブタンガスよりもア
ルコールガスに対する感度が高いものとなつてい
る。またＰのみあるいはPtのみを含む触媒層を用
いた場合も同様の傾向を示し、イソブタンガスの
みを検出することは困難であつた。これに対し本
発明に係る感ガス素子ではイソブタンガスのみに
対し優れた感度を示し、他のガスに対してはほと
んど感度が変らず選択性に優れたものと言える。
このように本発明において優れた選択性を示す原
因は明らかではないが、PtとＰとが混合されるた
め反応性が高く、触媒層の製造工程で添加された
PtとＰの少なくとも一部が化合物化されているた
めと考えられる。
また上記実施例においてはガス感応体として
SnO2―SiO2系半導体を用いたが、必要に応じ他
の酸化錫系半導体を用いても同様の効果を有する
ことは言うまでもない。
さらに本発明においては触媒層とガス感応体と
が分離されているため製造が容易である上、経時
特性にも優れるという利点を有する。
なおPtおよびＰをガス感応体中に混合した場合
も選択性の点においては従来のものに比べ向上す
るものと思われる。
以上の如く本発明に係る感ガス素子を用いるこ
とにより、イソブタンガスのみに対し高い感度を
有するため、LPG用感ガス素子として実用上極め
て有効なものと言える。[Table] As is clear from the results in Table 1, in the case of no catalyst, the overall sensitivity is low and the sensitivity to alcohol gas is higher than to isobutane gas. A similar tendency was observed when a catalyst layer containing only P or only Pt was used, and it was difficult to detect only isobutane gas. On the other hand, the gas-sensitive element according to the present invention exhibits excellent sensitivity only to isobutane gas, and can be said to have excellent selectivity with almost no change in sensitivity to other gases.
Although the reason for the excellent selectivity in the present invention is not clear, the reactivity is high because Pt and P are mixed, and Pt and P are added in the process of manufacturing the catalyst layer.
This is thought to be because at least a portion of Pt and P are compounded. In addition, in the above embodiment, as a gas sensitive body,
Although a SnO 2 --SiO 2 based semiconductor was used, it goes without saying that other tin oxide based semiconductors may be used as needed to achieve similar effects. Further, in the present invention, since the catalyst layer and the gas sensitive body are separated, it is easy to manufacture and has the advantage of having excellent aging characteristics. It is also believed that when Pt and P are mixed into the gas sensitive material, the selectivity is improved compared to the conventional one. As described above, by using the gas-sensitive element according to the present invention, it has high sensitivity only to isobutane gas, so it can be said that it is extremely effective in practice as a gas-sensitive element for LPG.
第１図は本発明に係る感ガス素子の構成例を示
す断面図、第２図は本発明に係る感ガス素子を用
いる装置例を示す斜視図、第３図および第４図は
本発明に係る感ガス素子の特性例を示す曲線図。
３…ガス感応体、４…触媒層。
FIG. 1 is a cross-sectional view showing a configuration example of a gas-sensitive element according to the present invention, FIG. 2 is a perspective view showing an example of a device using the gas-sensitive element according to the present invention, and FIGS. FIG. 3 is a curve diagram showing an example of the characteristics of such a gas-sensitive element. 3... Gas sensitive body, 4... Catalyst layer.
Claims (1)
ガス感応体の表面に、触媒担体に対し0.005〜８
重量％のPtと、モル比で前記Ptの1.5〜30倍のＰ
とを含む触媒層を設けたことを特徴とする感ガス
素子。1. On the surface of a gas sensitive body made of a tin oxide semiconductor having a pair of electrodes, an amount of 0.005 to 8
Pt in weight% and P in a molar ratio of 1.5 to 30 times that of the above Pt.
A gas-sensitive element comprising a catalyst layer comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5236878A JPS54145197A (en) | 1978-05-02 | 1978-05-02 | Gas sensitive element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5236878A JPS54145197A (en) | 1978-05-02 | 1978-05-02 | Gas sensitive element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS54145197A JPS54145197A (en) | 1979-11-13 |
| JPS6122776B2 true JPS6122776B2 (en) | 1986-06-03 |
Family
ID=12912860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5236878A Granted JPS54145197A (en) | 1978-05-02 | 1978-05-02 | Gas sensitive element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS54145197A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60170759A (en) * | 1984-02-16 | 1985-09-04 | Matsushita Electric Ind Co Ltd | Combustible gas detecting element |
| KR100780076B1 (en) * | 2001-11-08 | 2007-11-29 | 허증수 | Method for forming sensitizer for semiconductor type gas sensor and semiconductor type gas sensor array |
-
1978
- 1978-05-02 JP JP5236878A patent/JPS54145197A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54145197A (en) | 1979-11-13 |
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