JPS62254047A - Manufacture of low alcohol sensitive gas sensor - Google Patents
Manufacture of low alcohol sensitive gas sensorInfo
- Publication number
- JPS62254047A JPS62254047A JP9718986A JP9718986A JPS62254047A JP S62254047 A JPS62254047 A JP S62254047A JP 9718986 A JP9718986 A JP 9718986A JP 9718986 A JP9718986 A JP 9718986A JP S62254047 A JPS62254047 A JP S62254047A
- Authority
- JP
- Japan
- Prior art keywords
- sensitivity
- gas sensor
- gas
- sensor
- alcohol
- 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.)
- Granted
Links
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 239000003054 catalyst Substances 0.000 claims abstract description 30
- 230000035945 sensitivity Effects 0.000 claims abstract description 24
- 239000002131 composite material Substances 0.000 claims abstract description 16
- 239000010948 rhodium Substances 0.000 claims abstract description 13
- 150000003283 rhodium Chemical class 0.000 claims abstract 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 5
- 239000011259 mixed solution Substances 0.000 claims description 5
- 238000000465 moulding Methods 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 150000003057 platinum Chemical class 0.000 claims description 2
- 239000007789 gas Substances 0.000 abstract description 31
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 13
- 239000001257 hydrogen Substances 0.000 abstract description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052703 rhodium Inorganic materials 0.000 abstract description 7
- 239000000243 solution Substances 0.000 abstract description 7
- 150000002431 hydrogen Chemical class 0.000 abstract description 5
- 229910000510 noble metal Inorganic materials 0.000 abstract description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 abstract description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 abstract description 4
- 239000007864 aqueous solution Substances 0.000 abstract description 4
- 229910052697 platinum Inorganic materials 0.000 abstract description 4
- 239000002253 acid Substances 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 3
- 229910021529 ammonia Inorganic materials 0.000 abstract description 2
- 235000019270 ammonium chloride Nutrition 0.000 abstract description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 abstract 2
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 abstract 1
- 238000001035 drying Methods 0.000 abstract 1
- 239000013049 sediment Substances 0.000 abstract 1
- 238000000926 separation method Methods 0.000 abstract 1
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 abstract 1
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 14
- 239000001282 iso-butane Substances 0.000 description 7
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical group [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 6
- 238000005470 impregnation Methods 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 229910002090 carbon oxide Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000002452 interceptive effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- 235000006693 Cassia laevigata Nutrition 0.000 description 1
- YZCKVEUIGOORGS-IGMARMGPSA-N Protium Chemical compound [1H] YZCKVEUIGOORGS-IGMARMGPSA-N 0.000 description 1
- 241000735631 Senna pendula Species 0.000 description 1
- 229910006826 SnOw Inorganic materials 0.000 description 1
- 206010041235 Snoring Diseases 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003426 co-catalyst Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- -1 ethanol and nol Chemical class 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000035987 intoxication Effects 0.000 description 1
- 231100000566 intoxication Toxicity 0.000 description 1
- 210000003127 knee Anatomy 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- PXXKQOPKNFECSZ-UHFFFAOYSA-N platinum rhodium Chemical compound [Rh].[Pt] PXXKQOPKNFECSZ-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- SONJTKJMTWTJCT-UHFFFAOYSA-K rhodium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Rh+3] SONJTKJMTWTJCT-UHFFFAOYSA-K 0.000 description 1
- 229940124513 senna glycoside Drugs 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
［発明の利用分野］
この発明は、アルコール感度の低い５ｎＯｔ系ガスセン
サの製造方法に関する。
［従来技術］
特開昭５１ １３０．２９９号は、ガスセンサの表面を
Ｐ ｔＳＰ ｄｓ Ｉ ｒ−１１，ｈ等の貴金属触媒
の一員らし、くけ複数員に、Ｌす、被覆することを開示
している。公報によれば、貴金属触媒は妨害ガスを接触
酸化により除去してガス選択性を高めろとし、酸化によ
る除去の順序として、−酸化炭素、水素、アルコール、
イソブタン、メタンの順を挙げている。また特開昭５４
−１０４，３９７号は、ＺｎＯの表面をＰ ｔ−ｒｔ
ｈ１合触媒で被覆したガスセンサを開示する。そして公
報は、被覆によりイソブタン感度がか４−かに上昇ずろ
としている。
ところで実際には、主たる妨害ガスはエタ、ノール等の
アルコール類であり、水素は重要な検出対象である。そ
こで、水素への感度を損ねず、選択的にアルコール感度
を低下きり−ることが必要となる。しかし公知の技術は
、解決策を示していない。
１発明のｎ的コ
この発明は、水素感度を損ねずに、選択的にアルコール
感度を低トさせることを、目的とする。
［発明の措成］
この発明は、５ｎＯｔ系ガス感ガス感応いたガスセンサ
の製造方法において、ガス感応体の成型後に、その表面
部にＩｚｈ−Ｐｔ複合触媒を添加することを特徴とする
。
添加は、Ｒｈ−ｐｔ混合溶液の含浸、あるいはＲｈ−ｉ
’を複合触媒を添加した５ｎＯｔによる、感応体の被覆
等により行えば良い。ｌｌｈとＰｔとの混合比は、モル
比で１／３≦Ｒｈ／ＰＬ≦６が好ましく、より好ましく
は０．４≦Ｒｈ／Ｉ’Ｌ≦５とする。添加量は、Ｒｈと
ＰＩとの合計で、ガス感応体のＳｎ０ｗ１ｇ当たり、例
えば２５ ｔｉ ｍｏｌ、／ ｇｓ ｎＯｔとし、この
１０倍ないり、、 ［／ Ｉ Ｏの範囲が良い。しかし
このＭは、ガス感応体の形状や、■７ｈ−Ｉ）を複合触
媒を添加する部分の厚さ等により変化し、−・律には定
まらない。
■く１ｌ−Ｐｔ複合触媒は、ガス感応体の表面部に添加
する。感応体全体に均一に加えると、効果が低く、か−
〕センザの温度依存性が大きくなり扱いにくい、。
［］実施例］
５ｌＩＣ１４水溶液をアンモニアで加水分解し、スズ酸
のゾルを沈殿さＵ゛る。沈殿に水を加えて遠心分離し７
、塩化アンモニウムを除く。７００℃で１時間、空気中
で焼成し、粉砕してＳｎｏｗを得る。
Ｓｈｏｗを、第１図に示４゛形状のガスセンサに成型４
′ろ。図において、（２）、（４）はヒータ並用の貴金
属電極、（６）はガス感応体で、その内部に電極（２）
、（４）を埋設セる。ガス感応体（６）のすさは約１．
５ｏ＋ｍ、幅は約３１１１Ｉ１１長さは約２ａ＋ｍで、
センサ１個当たりのＳｎ、Ｏｔ量は約３０ｍｇである。
ＳｎＯ，にはＰｄ等の貴金属触媒やアルミナ等の骨材、
あるいは適宜のバインダー等を加えても良い。
表面に添加するｐｔ−Ｒｈ複合触媒と、これらの添加物
とは独立に作用し、その間には複合作用はない。センサ
の形状には、他に任意のものを用いることができる。電
極をガス感応体（６）に埋設せず、電極と感応体を別に
製造し得る場合は、感応体の成型後に電極を別に取り付
けても良い。しかし第を図の構造では、成型後に電極を
取り付けるのは困難なので、成型時に一体に電極を埋設
する。成型後のガス感応体（６）を８００℃に５分間加
熱し、焼結を行う。なおＲｈ−Ｐｔ複合触媒の添加時に
、感応体の強度を維持でき、溶液の含浸により感応体が
変形しないならば、焼結は含浸後に行っても良く、また
焼結工程を省略しても良い。
０．０５ｍｏｌ／１程度のＲｈやＰ[Field of Application of the Invention] The present invention relates to a method for manufacturing a 5nOt gas sensor with low alcohol sensitivity. [Prior Art] JP-A-51-130.299 discloses that the surface of a gas sensor is coated with a plurality of noble metal catalysts such as PtSPdsIr-11,h. There is. According to the publication, the noble metal catalyst removes interfering gases by catalytic oxidation to improve gas selectivity, and the order of removal by oxidation is - carbon oxide, hydrogen, alcohol,
It lists isobutane and methane in that order. Also, JP-A-54
-104,397, the surface of ZnO is P t-rt
A gas sensor coated with h1 catalyst is disclosed. The publication states that coating increases the isobutane sensitivity by as much as 4 points. However, in reality, the main interfering gases are alcohols such as ethanol and nol, and hydrogen is an important detection target. Therefore, it is necessary to selectively reduce the alcohol sensitivity without impairing the sensitivity to hydrogen. However, known techniques do not provide a solution. 1. N-characteristics of the invention An object of the present invention is to selectively lower alcohol sensitivity without impairing hydrogen sensitivity. [Measures of the Invention] The present invention is a method for manufacturing a gas sensor sensitive to a 5nOt gas, and is characterized in that after the gas sensitive body is molded, an Izh-Pt composite catalyst is added to the surface thereof. Addition is done by impregnation with a Rh-pt mixed solution or Rh-i
' may be carried out by coating the sensitive body with 5nOt added with a composite catalyst. The mixing ratio of llh and Pt is preferably 1/3≦Rh/PL≦6 in terms of molar ratio, and more preferably 0.4≦Rh/I'L≦5. The amount to be added is, for example, 25 tmol/gsnOt in total of Rh and PI per gram of SnOw of the gas sensitive material, and preferably in the range of 10 times this amount or [/I O. However, this M varies depending on the shape of the gas sensitive body, the thickness of the part where the composite catalyst is added (7h-I), etc., and is not fixed in a fixed manner. (1) The 1l-Pt composite catalyst is added to the surface of the gas sensitive member. If added uniformly to the entire sensitive body, the effect will be low and -
] The temperature dependence of the sensor becomes large, making it difficult to handle. [Example] A 5l IC14 aqueous solution is hydrolyzed with ammonia to precipitate a stannic acid sol. Add water to the precipitate and centrifuge 7
, excluding ammonium chloride. Calcinate in air at 700° C. for 1 hour and grind to obtain Snow. Show is molded into a 4"-shaped gas sensor as shown in Figure 1.
'reactor. In the figure, (2) and (4) are noble metal electrodes that can be used as heaters, and (6) is a gas sensitive body, inside which is an electrode (2).
, (4) is buried. The height of the gas sensitive body (6) is approximately 1.
5o+m, width is about 3111I11, length is about 2a+m,
The amount of Sn and Ot per sensor is approximately 30 mg. For SnO, noble metal catalysts such as Pd and aggregates such as alumina,
Alternatively, an appropriate binder or the like may be added. The pt-Rh composite catalyst added to the surface and these additives act independently, and there is no combined effect between them. Any other shape of the sensor can be used. If the electrodes are not embedded in the gas sensitive body (6) and the electrodes and the sensitive body can be manufactured separately, the electrodes may be attached separately after the sensitive body is molded. However, in the structure shown in Fig. 3, it is difficult to attach the electrodes after molding, so the electrodes are embedded integrally during molding. The molded gas sensitive body (6) is heated to 800° C. for 5 minutes to perform sintering. Note that when the Rh-Pt composite catalyst is added, if the strength of the sensitive body can be maintained and the sensitive body is not deformed by impregnation with the solution, sintering may be performed after impregnation, or the sintering step may be omitted. . Rh and P of about 0.05 mol/1
【等の水溶液を調製
する。水溶液は例えば、塩化ロジウムと塩化白金酸の混
合溶液とし、他の塩の溶液や、アルコール等の他の溶媒
を用いても良い。触媒溶液を感応体１個当たり１０μｌ
ずつ、感応体（６）に滴下し、酔抛後に７００′ｃ″’
７３１ ［’）分間加賦１．−ロジウム塩等を熱分解す
る。熱分解後の触媒の存在状態は、複雑で、雰囲気によ
り変化する。なお以下全ての実施例で、滴下ｍはセンサ
Ｉｇ当たり、１０μｌとする。添加量はｌＯ倍〜１／ｌ
Ｏ倍程度に変化さＵても良く、触媒の添加は滴下によら
ず感応体（６）を溶液中に浸して行ってら良い。また滴
下は１回ではなく複数回行っても良く、ロジウムとブラ
ヂ→−とを別に滴下しても良い。上記の過程で、１１ｈ
−Ｐｔの複合触媒が感応体（６）の表面部に担持される
。触媒は感応体（６）の表面部（８）に分布し、内部に
はほとんど存在しない。ロジウム−プラチナ触媒が存在
する深さは、Ｏ２ｉ〜０．３ｍｍ程度である。含浸法の
場合、特に注意を払わない限り、触媒は感応体の表面に
偏析する。
他の実施例として、焼結前の感応体（６）を、予めＲｈ
−ＰＬ′ｆＪｉ合触媒を添助触媒５ｎＣ）ｙ粉末で被覆
し、焼結を行っノこものを製造する。被覆に用いるＳｎ
Ｏ，はセンサ１個当たりＩＯＩｍｇとし、ロジウム量は
センサ１個当たり１７μｍｏｌ、プラチナ量はセンサ１
個当たり８．５μｍｏｌとする。これは、０ 、 ０５
ｍｏｌ／ＩのＣｉジウム塩と０ 、 ０２５ｍｏｌ／１
のプラチナ塩との混合溶液を含浸さＵ゛たものに相当す
る。このものの特性は、混合溶液を含浸させた場合と同
等でシったので、以下説明を省略する。
比較例として、焼成後のＳｎＯ，にＲｈ〜Ｐｔ複合触媒
を均一に添加１．ガス感応体（６）としたもの、Ｒｈ単
味の溶液等を含浸させたもの、Ｒ，ｂ〜Ｐｔ１合触媒を
担持したアルミナで感応体（６）を被覆した乙の、等を
調製する。
各センサを５個ずつ用い、２０°Ｃの湿度６５％の雰囲
気で特性を評価″４′る。最初に第２図〜第８図に、３
００〜５００℃での加熱温度と抵抗値との関係を示す。
各ガス濃度は２ｏｏｏｐｐｍであり、４００℃のイソブ
タン中での抵抗値を基準としζ示す。表１に、ｌｌｈや
ｐｔ等の添加量を示す。
表 １ （図の試料）
図 ・小・加里 （・ｔ４ 、＋ｎｏ ！／ター
イ型・Σ・・・第２図 ＲＩｉｏ、５、 ＰＬＯ，２５
第３図 ｒｌｈＯ，５、ｉ’ｔｏ、５第４図 Ｘえ
ｂＯ，２５、Ｉ）ｔ Ｏ，５第５図Ｒｈ０５５ １
１１味
第６図 １’ｔＯ，５！ｐ味
第７図 Ｐｄ Ｏ，５ｒ’Ｌ Ｏ，２５第８図 ｌＮ
ｂ０１５、 ｉ’ｔ Ｉ） 、 ２５（均一に添加した
比較例）
第２図〜第７図の特性は、エタノールと池のガス、特に
水素との相対感度が異なっている。ｊ４ｉお実際には、
エタノールはアルコール類を代表するもので、メタノー
ルやイソプロパツール等の他のアルコールへの特性は、
エタノールへの特性と類似する。
第２図の実施例では、エタノール感度は選択的に低下し
ており、４００℃での水素感度はエタノール感度より充
分に高い。この傾向は、第３図、第４図の実施例でも保
たれている。
エタノール感度の選択的抑制は、他の触媒では得られな
い。第５図のロジウム単味の場合、エタノール中の抵抗
値は水素中の抵抗値よりも低い。
次に第６図のプラチナ単味の場合、エタノールの感度は
かなり高い。パラディラム触媒の場合、図示を省略した
が、エタノール感度の抑制はロジウムの場合とほぼ同等
である。しかしパラディラム、プラチナの複合触媒では
（第７図）、水素感度が低下している。
第８図に、原料のＳｎｏｗの段階で、Ｒｈ−Ｐ＋複合触
媒を均一に添加したものの特性を示す。ロジウム等の添
加量は第２図のものと同等であるにもかかわらず、相対
感度は全く異なり、センサの温度依存性が大きい。実用
的には、センナの抵抗温度係数は、検知温度付近でＯな
いしわずかに正であることが要求される。抵抗温度係数
が負の場合、電源電圧の変動が、加熱電圧の変動とセン
サに加える検出電圧の変動とに相乗し、検出誤差が増す
。
表２に、エタノールと水素やイソブタンとの相々、シ虐
Ｉ午心壬七
青−一λ−１Ｌモ２ノニ火（Ｑｊさυへ仰り一添加ＩＩ
ｔ 相対感度（Ｉｊ／Ｉｌ’） ご
；法レベル（ｐｐｍ）（ｌ１４ｏ、ｉ／ササ−６５１−
ン １・いコＩＩ／ 鼾Ｊｔ」氾η−１、ｊ−／ニ
ー１１ 人ｊｊ＊Ｉ（ｌ剪２２轡段ン↓２懸Ｈ１）旧＋
０．５ ０゜７１ １．５ （ｉ０
０重味
２）Ｉｉｌ＋０．５ １．８ ４
２５００１’ＬＯ，１２５
３）ｌｊｈＯ，５２，０４，，５，１０００１’ｔＯ，
２５
４）旧】Ｏ１５１，６４２２００
１’ＬＱ、５
５）旧＋０．２５ １．４ ３．３
１８００１’ｔ０．５
６）Ｉ’ｔＯ，５０，４３１，５：（００中味
７）Ｉ’ｄＯ，５０，６５２，３５００重味
ノく・・２・（粒々・ン
添加’ｉｌ 相対感度（Ｉｔ／Ｉｊ’）
誤報レベル（ｐｐ白）−（μｍｍａｔ／（ｒ：ｚ
Ｑ −ｊ；ＬＱＩＩ〆Ｉｊ５．−！’ン、ＬＯ，，
，，，，ｌｌ／上！ｌ （Ｉｊ；１１ｉ、、Ｉ：ｊｆ
ｉｐ卯欺Ｅ、９）８）ｌ’（１０，５０，５２２，１４
００！’ｔＯ，２５
９）１えＩｉｏ、５ ０．６５
５００１ｒ ０． ２５
１１１）Ｉｊｈ Ｏ，５０，［１８５００１肖１０．
２５
１１）１ζｂＯ，５０，６５００
１’ｔＯ，２５アルミナに担持さｔｌ肢覆、（ｌノウム
イノプラチナの添加量は試料３）に同じ。
（１）添加は、Ｉ）〜１０）は含浸法で、１１）はアル
ミナイこ旧ｌ−１’ｔｌＱ合触媒を１１劃ト贋さ０セン
ザを被覆、
（２）ｘ、クノール中と水素中との低り’Ｌ値の比、及
びエタノール中とイソブタン中との抵ｂ”ｉ ｉｐ’ｉ
の比を相対感度として示し、この値が高い程誤ｆ！ｔ、
、−にくい。
（３）水素１［１０ａｐｌ）ａに検出レベルを設定した
場合の、エタノールでの誤報が生じろ濃１．１′。
表２から、１ｊｈ−Ｐｔ複合触媒の利用により、アルコ
ールによる誤報レベルを４倍程度増大さ１１得ることが
わかる。なお、相対感度以外の特性、例えばガス濃度へ
の出力の依存性や経時特性に付いては、実施例のセンサ
は比較例のらのと同様で有った。またこのセンサは、水
素、イソブタン、メタン等のガスのみでなく、−酸化炭
素の検出にも用いろことが出来る。
［発明の効果Ｊ
この発明では、ガスセンサのアルコールによる誤報を除
くことが出来る。Prepare an aqueous solution of [etc. The aqueous solution is, for example, a mixed solution of rhodium chloride and chloroplatinic acid, and solutions of other salts or other solvents such as alcohol may also be used. 10μl of catalyst solution per sensitizer
700'c''' after intoxication.
731 [') Minute addition 1. - Thermal decomposition of rhodium salts, etc. The state of the catalyst after thermal decomposition is complex and changes depending on the atmosphere. In all the examples below, the dropping m is 10 μl per sensor Ig. Addition amount is 10 times ~ 1/l
The catalyst may be added by immersing the reactor (6) in the solution instead of dropping it dropwise. Further, the dropping may be performed not once but multiple times, and rhodium and brazi →- may be dropped separately. In the above process, 11 hours
-Pt composite catalyst is supported on the surface of the sensitive body (6). The catalyst is distributed on the surface (8) of the sensitive body (6), and is hardly present inside. The depth at which the rhodium-platinum catalyst exists is about O2i~0.3 mm. In the case of impregnation methods, the catalyst segregates on the surface of the susceptor unless special precautions are taken. As another example, the sensitive body (6) before sintering is
-PL'fJi combined catalyst is coated with 5nC)y powder of added co-catalyst and sintered to produce a saw. Sn used for coating
O, is IOImg per sensor, the amount of rhodium is 17 μmol per sensor, and the amount of platinum is IOImg per sensor.
The amount is 8.5 μmol per piece. This is 0, 05
mol/I of Ci diium salt and 0,025 mol/1
This corresponds to the one impregnated with a mixed solution of platinum salt. The characteristics of this product were the same as those obtained when the mixed solution was impregnated, so the description thereof will be omitted below. As a comparative example, a Rh-Pt composite catalyst was uniformly added to SnO after firing.1. A gas sensitive material (6), a material impregnated with a solution of Rh alone, and a material (B) in which the sensitive material (6) is coated with alumina supporting an R, b to Pt1 combined catalyst are prepared. Using five of each sensor, the characteristics were evaluated in an atmosphere of 20°C and 65% humidity.First, Figures 2 to 8 show 3.
The relationship between heating temperature and resistance value at 00 to 500°C is shown. The concentration of each gas is 2oooppm, and the resistance value in isobutane at 400° C. is used as a reference. Table 1 shows the amounts of llh, pt, etc. added. Table 1 (Samples in the figure) Figure ・Kari (・t4, +no!/Thai type・Σ...Figure 2 RIio, 5, PLO, 25
Figure 3 rlhO,5,i'to,5Figure 4XebO,25,I)t O,5Figure 5Rh055 1
11th taste Figure 6 1'tO, 5! p taste Fig. 7 Pd O, 5r'L O, 25 Fig. 8 lN
b015, i't I), 25 (Comparative Example with Uniform Addition) The characteristics shown in FIGS. 2 to 7 differ in the relative sensitivity between ethanol and pond gas, especially hydrogen. j4i actually,
Ethanol is a representative alcohol, and the characteristics of other alcohols such as methanol and isopropanol are
Similar properties to ethanol. In the example of FIG. 2, the ethanol sensitivity is selectively reduced, and the hydrogen sensitivity at 400° C. is sufficiently higher than the ethanol sensitivity. This tendency is maintained in the embodiments shown in FIGS. 3 and 4. Selective suppression of ethanol sensitivity is not obtained with other catalysts. In the case of rhodium alone in FIG. 5, the resistance value in ethanol is lower than the resistance value in hydrogen. Next, in the case of single platinum shown in Figure 6, the sensitivity to ethanol is quite high. In the case of a paradilum catalyst, although not shown, the suppression of ethanol sensitivity is almost the same as in the case of rhodium. However, in the composite catalyst of paradilum and platinum (Figure 7), the hydrogen sensitivity is reduced. FIG. 8 shows the characteristics of a product in which the Rh-P+ composite catalyst was uniformly added at the snow stage of the raw material. Although the amount of added rhodium, etc. is the same as that shown in FIG. 2, the relative sensitivity is completely different, and the temperature dependence of the sensor is large. Practically speaking, the temperature coefficient of resistance of the senna is required to be O or slightly positive near the sensing temperature. When the temperature coefficient of resistance is negative, fluctuations in the power supply voltage multiply with fluctuations in the heating voltage and fluctuations in the detection voltage applied to the sensor, increasing detection errors. Table 2 shows the combination of ethanol, hydrogen and isobutane, and the combination of ethanol and hydrogen and isobutane.
t Relative sensitivity (Ij/Il') Legal level (ppm) (I14o, i/Sasa-651-
N 1・Iko II/ Snoring Jt” flood η-1, j-/knee 11 people jj*I (l 22 轡dann ↓ 2 hang H1) old +
0.5 0゜71 1.5 (i0
0 weight 2) Iil+0.5 1.8 4
25001'LO,125 3)ljhO,52,04,,5,10001'tO,
25 4) Old] O151,642200 1'LQ, 5 5) Old +0.25 1.4 3.3
18001't0.5 6) I'tO, 50,431,5: (00 content 7) I'dO, 50,652,3500 heavy taste...2 (grains/n addition'il Relative sensitivity (It /Ij')
False alarm level (pp white) - (μmmat/(r:z
Q −j;LQII〆Ij5. -! 'n, LO,,
,,,,ll/top! l (Ij; 11i, , I:jf
ip deception E, 9) 8) l' (10, 50, 522, 14
00! 'tO, 25 9) 1eIio, 5 0.65
5001r 0. 25 111) Ijh O, 50, [185001 Port 10.
25 11) 1ζbO, 50,6500 1'tO, 25 tl supported on alumina, (the added amount of innoplatinum is the same as sample 3). (1) Addition is by impregnation method for I) to 10), 11) coating of alumina old l-1'tlQ combined catalyst, (2) x, in Knorr and in hydrogen. and the ratio of the lower 'L value and the resistance b"i ip'i in ethanol and in isobutane.
The ratio of f! t,
, - difficult. (3) If the detection level is set to hydrogen 1 [10 apl) a, a false alarm will occur due to ethanol concentration 1.1'. From Table 2, it can be seen that the use of the 1jh-Pt composite catalyst increases the level of false alarms due to alcohol by about 4 times. Note that the sensor of the example was similar to the comparative example in terms of characteristics other than relative sensitivity, such as dependence of output on gas concentration and characteristics over time. Furthermore, this sensor can be used to detect not only gases such as hydrogen, isobutane, and methane, but also -carbon oxide. [Effect of the Invention J According to the present invention, false alarms caused by alcohol in the gas sensor can be eliminated.
第１図は、実施例で製造するガスセンサの断面図、第２
図〜第４図は、実施例のガスセンサの特性図、第５図〜
第８図は従来例のガスセンサの特性図である。
（６）ガス感応体、（８）表面部。Figure 1 is a sectional view of the gas sensor manufactured in the example,
Figures ~ 4 are characteristic diagrams of the gas sensor of the example, and Figures 5 ~
FIG. 8 is a characteristic diagram of a conventional gas sensor. (6) gas sensitive body, (8) surface portion.
Claims (4)
造方法において、 前記ガス感応体の成型後に、その表面部にＲｈ−Ｐｔ複
合触媒を添加することを特徴とする、低アルコール感度
ガスセンサの製造方法。(1) A method for manufacturing a gas sensor using a SnO_2-based gas sensor, which comprises adding a Rh-Pt composite catalyst to the surface of the gas sensor after molding. .
ウム塩とプラチナ塩との混合溶液に、ガス感応体を接触
させ、Ｒｈ−Ｐｔ複合触媒を添加することを特徴とする
、低アルコール感度ガスセンサの製造方法。(2) The method according to claim 1, characterized in that a gas sensitive material is brought into contact with a mixed solution of a rhodium salt and a platinum salt, and a Rh-Pt composite catalyst is added. Gas sensor manufacturing method.
Ｏ＿２にＲｈ−Ｐｔ複合触媒を添加した粉末を調製し、
この粉末によりガス感応体を被覆することを特徴とする
、低アルコール感度ガスセンサの製造方法。(3) In the method according to claim 1, Sn
Prepare a powder in which Rh-Pt composite catalyst is added to O_2,
A method for manufacturing a low alcohol sensitivity gas sensor, which comprises coating a gas sensitive member with this powder.
て、 ＲｈとＰｔとのモル比は、１／３〜６であることを特徴
とする、低アルコール感度ガスセンサの製造方法。(4) A method for manufacturing a low alcohol sensitivity gas sensor according to claims 1 to 3, wherein the molar ratio of Rh to Pt is 1/3 to 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61097189A JPH0814557B2 (en) | 1986-04-25 | 1986-04-25 | Method for manufacturing low-alcohol sensitive gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61097189A JPH0814557B2 (en) | 1986-04-25 | 1986-04-25 | Method for manufacturing low-alcohol sensitive gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62254047A true JPS62254047A (en) | 1987-11-05 |
| JPH0814557B2 JPH0814557B2 (en) | 1996-02-14 |
Family
ID=14185626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61097189A Expired - Fee Related JPH0814557B2 (en) | 1986-04-25 | 1986-04-25 | Method for manufacturing low-alcohol sensitive gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0814557B2 (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5999243A (en) * | 1982-11-29 | 1984-06-07 | Toshiba Corp | Gas sensitive element |
-
1986
- 1986-04-25 JP JP61097189A patent/JPH0814557B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5999243A (en) * | 1982-11-29 | 1984-06-07 | Toshiba Corp | Gas sensitive element |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0814557B2 (en) | 1996-02-14 |
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