JPH09229890A - Catalyst for gas sensor and activation processing method for the catalyst - Google Patents
Catalyst for gas sensor and activation processing method for the catalystInfo
- Publication number
- JPH09229890A JPH09229890A JP4021096A JP4021096A JPH09229890A JP H09229890 A JPH09229890 A JP H09229890A JP 4021096 A JP4021096 A JP 4021096A JP 4021096 A JP4021096 A JP 4021096A JP H09229890 A JPH09229890 A JP H09229890A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- gas sensor
- heat treatment
- palladium
- gas
- 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
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
【発明の属する技術分野】この発明は、可燃性ガスを検
知するための接触燃焼式ガスセンサに用いる、金属酸化
物に担持された少なくともパラジウムを含むガスセンサ
用触媒とその活性化処理方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for a gas sensor containing at least palladium supported on a metal oxide used in a catalytic combustion type gas sensor for detecting a combustible gas, and an activation treatment method thereof.
【従来の技術】図4は接触燃焼式ガス検知装置のブリッ
ジ回路図である。2つの固定抵抗R1、R2の直列接続
と、ガス検知素子Dと補償素子Cの直列接続に電源E
(電圧Vc)負荷Wがそれぞれ並列接続されている。電
圧Vcのブリッジ回路への印加によって通電、予熱され
たガス検知素子Dに可燃性ガスが接触すると燃焼が起こ
り、白金コイルに温度上昇が生じて、ガス濃度に比例し
た電気抵抗上昇を生じる。補償素子では燃焼は起こらず
可燃性ガスが来てもほとんど温度変化を生じない。その
結果生ずる電圧差(ブリッジ出力)が負荷Wに印加され
る。ブリッジ出力はガス濃度に比例して上昇するので、
ガス濃度を検知できる。図5は従来の接触燃焼式ガスセ
ンサのガス検知素子を示す要部破断斜視図である。白金
コイルなどからなる測温抵抗体1の周囲に白金とパラジ
ウムなどの触媒3の担持されたアルミナなどの担体2が
固着されている。このような従来の接触燃焼式ガスセン
サのガス検知素子および補償素子は次のようにして製造
される。直径60μmの白金線を用い、外形0.6m
m,巻回数10ターン、長さ1.5mmのコイルを製造
する。白金コイルの測温抵抗体1にアルミナ粉末とアル
ミナゾルの混合したペーストを付着させ800℃で焼成
してアルミナ担体2を白金コイルの測温抵抗体1に固着
させる。アルミナ担体2を塩化白金酸と塩化パラジウム
を溶かした水溶液中に含浸し、600℃で加熱分解し
て、白金と酸化パラジウムの混合触媒3をアルミナ担体
2に担持してガス検知素子Dを製造する。同様に補償素
子は白金コイルにアルミナ粉末とアルミナゾルの混合し
たペーストを付着させ800℃で焼成してアルミナ担体
を白金コイルに固着させる。アルミナ担体を硫酸銅を溶
かした水溶液中に含浸し、加熱分解して酸化銅触媒をア
ルミナ担体に担持して補償素子を製造する。上述のよう
な従来の接触燃焼式ガスセンサの製造方法は作製が簡単
なこと、実用上問題がない特性を有すること、長期安定
性が比較的優れていること、周囲温度や湿度による影響
が少ない等の特徴を有し、約0.5Wの消費電力で使用
される。2. Description of the Related Art FIG. 4 is a bridge circuit diagram of a catalytic combustion type gas detector. The power supply E is connected to the series connection of the two fixed resistors R1 and R2 and the series connection of the gas detection element D and the compensation element C.
(Voltage Vc) Loads W are connected in parallel. When the combustible gas comes into contact with the gas detection element D that has been energized and preheated by applying the voltage Vc to the bridge circuit, combustion occurs, the temperature of the platinum coil rises, and the electric resistance increases in proportion to the gas concentration. Combustion does not occur in the compensating element, and almost no temperature change occurs even if combustible gas comes in. The resulting voltage difference (bridge output) is applied to the load W. Since the bridge output rises in proportion to the gas concentration,
The gas concentration can be detected. FIG. 5 is a fragmentary perspective view showing a gas detecting element of a conventional catalytic combustion gas sensor. A carrier 2 such as alumina carrying a catalyst 3 such as platinum and palladium is fixed around a resistance temperature detector 1 including a platinum coil. The gas detecting element and compensating element of such a conventional catalytic combustion type gas sensor are manufactured as follows. Using platinum wire with a diameter of 60 μm, outline 0.6 m
A coil having m, the number of turns of 10 turns, and a length of 1.5 mm is manufactured. A paste containing a mixture of alumina powder and alumina sol is adhered to the resistance measuring element 1 of the platinum coil and fired at 800 ° C. to fix the alumina carrier 2 to the resistance measuring element 1 of the platinum coil. The alumina carrier 2 is impregnated in an aqueous solution in which chloroplatinic acid and palladium chloride are dissolved and thermally decomposed at 600 ° C., and the mixed catalyst 3 of platinum and palladium oxide is supported on the alumina carrier 2 to manufacture the gas detection element D. . Similarly, in the compensating element, a mixed paste of alumina powder and alumina sol is adhered to a platinum coil and fired at 800 ° C. to fix the alumina carrier to the platinum coil. An alumina carrier is impregnated in an aqueous solution in which copper sulfate is dissolved and thermally decomposed to carry a copper oxide catalyst on the alumina carrier to manufacture a compensating element. The conventional method of manufacturing a catalytic combustion gas sensor as described above is easy to manufacture, has characteristics that pose no practical problems, has relatively long-term stability, is less affected by ambient temperature and humidity, etc. It has the characteristics of and is used with a power consumption of about 0.5 W.
【発明が解決しようとする課題】しかしながら、上述の
ような従来の接触燃焼式ガスセンサでは、個々の素子形
状(担体)作製後触媒の担持工程を行うため、素子1個
毎の取扱が煩雑であるという問題がある上に、担持後の
加熱分解だけでは活性化が未だ十分でないという問題も
あった。この発明は上述の点に鑑みてなされ、その目的
は触媒活性を増大させ、さらに高いセンサ出力を発生さ
せるための活性化処理方法を提供することにある。However, in the conventional catalytic combustion type gas sensor as described above, since the step of carrying the catalyst is performed after the production of individual element shapes (supports), the handling of each element is complicated. In addition to the above problem, there is also a problem that activation by thermal decomposition after loading is still insufficient. The present invention has been made in view of the above points, and an object thereof is to provide an activation treatment method for increasing catalyst activity and generating a higher sensor output.
【課題を解決するための手段】上記の目的を達成するた
めに、金属酸化物からなる担体に担持され、少なくとも
パラジウムを含むガスセンサ用触媒の活性化処理方法に
おいて、前記触媒を可燃性ガスおよび水蒸気を含む空気
中で行う第1の熱処理と、その後さらに乾燥空気中で行
う第2の熱処理を行うこととする。前記第1の熱処理
は、メタンガスを0.5〜2%含み、露点が30℃以下
の水蒸気を含む空気を300ないし500℃に昇温した
雰囲気中で、5時間以上行うと良い。また、前記第2の
熱処理は、温度は400ないし500℃の乾燥空気中
で、2時間以上行うと良い。前記金属酸化物はγ−アル
ミナまたは酸化スズであると良い。前記触媒はパラジウ
ムと白金であると良い。また、金属酸化物からなる担体
に担持され、少なくともパラジウムを含むガスセンサ用
触媒において、前記パラジウムの形態を水酸化パラジウ
ムが酸化された酸化パラジウムとする。In order to achieve the above object, in a method for activating a gas sensor catalyst which is supported on a carrier made of a metal oxide and contains at least palladium, the catalyst is a flammable gas and steam. The first heat treatment is performed in the air containing H2O, and the second heat treatment is further performed in the dry air thereafter. The first heat treatment is preferably performed for 5 hours or more in an atmosphere in which methane gas is contained in an amount of 0.5 to 2% and water vapor having a dew point of 30 ° C. or lower is heated to 300 to 500 ° C. In addition, the second heat treatment may be performed in dry air at a temperature of 400 to 500 ° C. for 2 hours or more. The metal oxide is preferably γ-alumina or tin oxide. The catalyst is preferably palladium and platinum. Further, in the catalyst for a gas sensor, which is supported on a carrier made of a metal oxide and contains at least palladium, the form of the palladium is palladium oxide in which palladium hydroxide is oxidized.
実施例1 この実施例では、メタンガス(CH4 )検知用の接触燃
焼式ガスセンサにおける触媒の活性化処理方法を説明す
る。市販のγ−アルミナ粉末をライカイ機で1時間以上
粉砕した後、純水に溶解した塩化白金酸溶液と塩化パラ
ジウムの水溶液と混合した。このとき水溶液の濃度は、
γ−アルミナに対して白金は10wt%となるよう、パ
ラジウムは12wt%となるように調整した。この混合
液をスタ−ラーにより10分間攪拌し、その後超音波洗
浄機で5分間分散させた。この攪拌、分散を3回繰り返
した後、60℃に設定したウォーターバス中で攪拌しな
がら蒸発乾固させた。蒸発乾固後、これをボールミルで
粉砕し、ガス検知素子用の触媒原料を担持した粉末を得
た。得られた粉末を石英ボートに移し、電気炉により、
乾燥空気中で150℃、1時間保持後、600℃に昇温
し3時間の熱処理を行い、触媒原料を熱分解した。図2
は触媒原料の熱分解の温度プロファイルである。この熱
分解により触媒原料は白金および酸化パラジウムとな
り、触媒となる。この状態を触媒粉末と称することにす
る。また同時に粉末から塩素が取り除かれるが、2〜3
wt%残留している。以上は従来の触媒調製方法と同じで
ある。このようにして作製された触媒粉末を次のように
活性化処理し、触媒活性を向上させた。触媒粉末を電気
炉に挿入し、乾燥空気に1体積%のメタンガスを混合し
た露点30℃の空気を所定の温度に昇温した雰囲気中
で、5時間、第1の熱処理を行った。その後さらに、乾
燥空気中で所定の温度(400℃)で2h以上の第2の
熱処理を行った。第1の熱処理後の触媒粉末のパラジウ
ムはX線回折によると水酸化物が主であり、CH4 に対
する酸化能は小さい。この水酸化物を酸化パラジウムに
変換するために第2の熱処理を行う必要がある。また、
水酸化物を経た酸化パラジウムがCH4 に対する酸化能
が大きくなっていることが極めて重要であるが、酸化能
増加をもたらす作用は判然としていない。一方、これら
の熱処理中に残留塩素は除去され、CH4 に対する酸化
能の少しの増加をもたらしていることも認められた。こ
のようにして得られた触媒粉末のCH4 に対する酸化能
を (株) 大倉理研製の固定床流通法触媒評価装置を用い
て測定した。この装置は、被検ガス(CH4)を含む空
気を素子上に流し、反応した被検ガスの反応消費の割合
を転化率(%)として測定するものである。試料として
触媒粉末50mgを用い、被検ガス流量は10sccm、被検
ガス濃度は1%とした。図1は本発明に係る活性化処理
を行った触媒粉末のCH4 の転化率の温度に対するグラ
フである。カーブaは第1の熱処理温度が450℃、カ
ーブbは同じく400℃、カーブcは同じく350℃の
場合であり、カーブd は活性化処理を行ってない場合で
ある。転化率が90%となる温度により比較すると、従
来の方法で作製された接触燃焼式ガスセンサの触媒は約
370℃であるが、本実施例で作製された接触燃焼式ガ
スセンサ用触媒は従来品より低温から活性が優れてお
り、350℃処理では345℃、400℃処理では30
5℃、450℃処理では325℃であった。以上から、
転化率が90%となる温度が従来触媒より低い処理温度
は400ないし500℃と推定できる。また、ガスセン
サは転化率が95%となる温度以上で使用されるので、
熱処理温度は400℃以上が適正である。次に、上記の
400℃での活性化処理の触媒粉末を用いたガスセンサ
のCH4に対する感度をしらべた。ガス検知素子と対と
して用いる補償素子用の触媒粉末の作製方法はガス検知
素子用の触媒の作製方法と同じであるが、触媒原料には
硝酸銅を純水に溶かしたものを使用することと、活性化
処理は特に行わないことが異なる。ガス検知素子および
補償素子は、各触媒粉末をそれぞれアルミナゾルと混合
し、白金コイルに付着し、600℃で焼結することによ
り作製した。図3は本発明に係る触媒粉末を用いたガス
センサをブリッジ回路に組み込んだ場合のCH4 に対す
るブリッジ出力のグラフである。カーブeは本発明に係
る触媒粉末を用いた場合、カーブfは活性化処理を行っ
てない場合である。本実施例の方法で作製した触媒を用
いたセンサは従来の方法で作製されたセンサに比べ、高
い出力が得られることが判る。このように本発明の触媒
の活性化処理方法を用いると従来品より出力を増加させ
ることができる。 実施例2 担体に酸化スズを用いた場合のCH4 ガスセンサ用触媒
の活性化処理方法を次に説明する。市販のスズ酸粉末を
電気炉により、空気中で730℃、3時間の熱処理を行
い、酸化スズ粉末を作製した。この粉末をライカイ機で
1時間以上粉砕した後、純水に溶解した塩化白金酸溶液
と塩化パラジウムの水溶液と混合した。このとき水溶液
の触媒原料の濃度は酸化スズに対して白金は10wt%
となるよう、パラジウムは12wt%となるように調整
した。この混合液をスタ−ラーにより10分間攪拌し、
その後超音波洗浄機で5分間分散させる。この攪拌、分
散を3回繰り返した後、60℃に設定したウォーターバ
ス中で攪拌しながら蒸発乾固させる。蒸発乾固後、これ
をボールミルにより粉砕し、ガス検知素子用の触媒原料
粉末を得た。これを石英ボートに移し、電気炉により乾
燥空気中で実施例1と同じ温度プロファイルの熱処理を
行ない、熱分解し触媒粉末を得た。このようにして作製
された触媒粉末を実施例1と同様に活性化処理し、触媒
活性を向上させた。すなわち、触媒粉末を電気炉に挿入
し、乾燥空気に1体積%のメタンガスを混合した露点3
0℃の空気を所定の温度に昇温した雰囲気中で、5時
間、第1の熱処理を行った。その後さらに、乾燥空気中
で400℃温度で2時間の第2の熱処理を行った。以
下、実施例1と同様に、触媒粉末のメタンガスに対する
酸化能およびガス検知素子としブリッジ回路に組み込ん
だ場合のブリッジ出力を調べたところ、実施例1とほと
んど同じカーブが得られた。すなわち、担体として酸化
スズを用いた場合でも、本発明の活性化処理法により触
媒を従来品より活性化することができ、実施例1と同様
にセンサの出力を増加させることが出来た。Example 1 In this example, a method for activating a catalyst in a catalytic combustion gas sensor for detecting methane gas (CH 4 ) will be described. Commercially available γ-alumina powder was crushed for 1 hour or more with a Likai machine, and then mixed with a chloroplatinic acid solution dissolved in pure water and an aqueous solution of palladium chloride. At this time, the concentration of the aqueous solution is
The platinum was adjusted to 10 wt% and the palladium was adjusted to 12 wt% with respect to γ-alumina. This mixed solution was stirred for 10 minutes with a stirrer and then dispersed for 5 minutes with an ultrasonic cleaner. After repeating this stirring and dispersion three times, the mixture was evaporated to dryness while stirring in a water bath set at 60 ° C. After evaporating to dryness, this was pulverized with a ball mill to obtain a powder carrying a catalyst raw material for a gas detection element. Transfer the obtained powder to a quartz boat, and by an electric furnace,
After being kept in dry air at 150 ° C. for 1 hour, the temperature was raised to 600 ° C. and heat treatment was performed for 3 hours to thermally decompose the catalyst raw material. FIG.
Is a temperature profile of thermal decomposition of the catalyst raw material. By this thermal decomposition, the catalyst raw material becomes platinum and palladium oxide and becomes a catalyst. This state will be referred to as catalyst powder. At the same time, chlorine is removed from the powder, but 2-3
wt% remains. The above is the same as the conventional catalyst preparation method. The catalyst powder thus produced was activated as follows to improve the catalytic activity. The catalyst powder was inserted into an electric furnace, and first heat treatment was performed for 5 hours in an atmosphere in which dry air was mixed with 1% by volume of methane gas and dew point of 30 ° C. was raised to a predetermined temperature. After that, a second heat treatment was further performed for 2 hours or more at a predetermined temperature (400 ° C.) in dry air. According to X-ray diffraction, palladium of the catalyst powder after the first heat treatment is mainly hydroxide, and its oxidizing ability for CH 4 is small. A second heat treatment needs to be performed to convert this hydroxide to palladium oxide. Also,
It is extremely important that the palladium oxide that has passed through the hydroxide has a large oxidizing ability with respect to CH 4 , but the effect of increasing the oxidizing ability is not clear. On the other hand, it was also found that residual chlorine was removed during these heat treatments, resulting in a slight increase in the oxidizing ability for CH 4 . The oxidizing ability of the thus obtained catalyst powder with respect to CH 4 was measured using a fixed bed flow method catalyst evaluation apparatus manufactured by Okura Riken Co., Ltd. In this device, air containing a test gas (CH 4 ) is caused to flow over the element, and the reaction consumption rate of the reacted test gas is measured as a conversion rate (%). 50 mg of catalyst powder was used as a sample, the flow rate of the test gas was 10 sccm, and the concentration of the test gas was 1%. FIG. 1 is a graph showing the temperature of the conversion rate of CH 4 of the catalyst powder subjected to the activation treatment according to the present invention. Curve a is the case where the first heat treatment temperature is 450 ° C., curve b is the same at 400 ° C., curve c is the same at 350 ° C., and curve d is the case where the activation treatment is not performed. When compared by the temperature at which the conversion rate becomes 90%, the catalyst of the catalytic combustion type gas sensor manufactured by the conventional method is about 370 ° C., but the catalyst for the catalytic combustion type gas sensor manufactured in this example is more than that of the conventional product. Excellent activity from low temperature: 350 ° C treatment at 345 ° C, 400 ° C treatment at 30
The temperature was 325 ° C. when treated at 5 ° C. and 450 ° C. From the above,
It can be estimated that the treatment temperature at which the conversion rate is 90% is lower than that of the conventional catalyst is 400 to 500 ° C. In addition, since the gas sensor is used at a temperature above the conversion rate of 95%,
A heat treatment temperature of 400 ° C. or higher is appropriate. Next, the sensitivity of the gas sensor using the catalyst powder of the activation treatment at 400 ° C. to CH 4 was examined. The method for producing the catalyst powder for the compensating element used as a pair with the gas detection element is the same as the method for producing the catalyst for the gas detection element, except that the catalyst raw material used is copper nitrate dissolved in pure water. The difference is that the activation process is not performed. The gas detecting element and the compensating element were produced by mixing each catalyst powder with alumina sol, adhering it to a platinum coil, and sintering it at 600 ° C. FIG. 3 is a graph of the bridge output for CH 4 when the gas sensor using the catalyst powder according to the present invention is incorporated in the bridge circuit. Curve e is the case where the catalyst powder according to the present invention is used, and curve f is the case where the activation treatment is not performed. It can be seen that the sensor using the catalyst manufactured by the method of the present embodiment can obtain a higher output than the sensor manufactured by the conventional method. As described above, when the catalyst activation treatment method of the present invention is used, the output can be increased as compared with the conventional product. Example 2 A method for activating a CH 4 gas sensor catalyst when tin oxide is used as a carrier will be described below. A commercially available stannic acid powder was heat-treated in the air at 730 ° C. for 3 hours in an electric furnace to prepare a tin oxide powder. This powder was crushed for 1 hour or more with a liquor machine, and then mixed with a chloroplatinic acid solution dissolved in pure water and an aqueous solution of palladium chloride. At this time, the concentration of the catalyst raw material in the aqueous solution was 10 wt% platinum for tin oxide.
So that the palladium content is adjusted to 12 wt%. Stir this mixture with a stirrer for 10 minutes,
Then, disperse in an ultrasonic cleaner for 5 minutes. After repeating this stirring and dispersion three times, the mixture is evaporated to dryness while stirring in a water bath set at 60 ° C. After evaporating to dryness, this was crushed by a ball mill to obtain a catalyst raw material powder for a gas detection element. This was transferred to a quartz boat, heat-treated in an electric furnace in dry air with the same temperature profile as in Example 1, and pyrolyzed to obtain a catalyst powder. The catalyst powder thus produced was activated in the same manner as in Example 1 to improve the catalytic activity. That is, the catalyst powder was inserted into an electric furnace, and 1% by volume of methane gas was mixed with dry air to form a dew point of 3
The first heat treatment was performed for 5 hours in an atmosphere in which 0 ° C. air was heated to a predetermined temperature. After that, a second heat treatment was further performed at a temperature of 400 ° C. for 2 hours in dry air. Then, as in Example 1, the oxidizing power of the catalyst powder with respect to methane gas and the bridge output when incorporated into a bridge circuit as a gas detection element were examined. As a result, almost the same curve as in Example 1 was obtained. That is, even when tin oxide was used as the carrier, the catalyst could be activated more than the conventional product by the activation treatment method of the present invention, and the output of the sensor could be increased as in Example 1.
【発明の効果】この発明によれば、金属酸化物からなる
担体に担持され、少なくともパラジウムを含むガスセン
サ用触媒の活性化処理方法において、前記触媒を可燃性
ガスおよび水蒸気を含む空気中で行う第1の熱処理と、
その後さらに乾燥空気中で行う第2の熱処理を行ない、
第1の熱処理により水酸化パラジウムを生成した後第2
の熱処理により酸化して酸化パラジウムを生成するよう
にし、さらに、添加可燃性ガスにより、同ガスに対する
活性化も併せおこなった。そのため、可燃性ガスに対す
る酸化能は向上し、これを用いたガスセンサを組み込ん
だブリッジ回路の出力は大きくなった。また、活性化処
理を粉末状態で行うため、一括して均一な特性を得るこ
とができ、個々のガスセンサを活性化処理するような煩
雑さを回避できる。According to the present invention, in a method for activating a catalyst for a gas sensor, which is supported on a carrier made of a metal oxide and contains at least palladium, the catalyst is carried out in air containing a combustible gas and water vapor. 1 heat treatment,
After that, a second heat treatment is performed in dry air,
The second after the palladium hydroxide is generated by the first heat treatment
It was oxidized by the heat treatment of (1) to generate palladium oxide, and further activated by the added combustible gas. Therefore, the ability to oxidize combustible gas was improved, and the output of the bridge circuit incorporating the gas sensor using the same was increased. In addition, since the activation treatment is performed in the powder state, uniform characteristics can be obtained all at once, and the complexity of activating the individual gas sensors can be avoided.
【図1】本発明に係る活性化処理を行った触媒粉末のC
H4 の転化率の温度に対するグラフFIG. 1 C of catalyst powder which has been activated according to the present invention
Graph of conversion rate of H 4 against temperature
【図2】触媒原料の熱分解の温度プロファイルFIG. 2 Temperature profile of thermal decomposition of catalyst raw material
【図3】本発明に係る触媒粉末を用いたガスセンサをブ
リッジ回路に組み込んだ場合のCH4 に対するブリッジ
出力のグラフFIG. 3 is a graph of bridge output for CH 4 when a gas sensor using the catalyst powder according to the present invention is incorporated in a bridge circuit.
【図4】接触燃焼式ガス検知装置のブリッジ回路図FIG. 4 is a bridge circuit diagram of the catalytic combustion type gas detection device.
【図5】従来の接触燃焼式ガスセンサのガス検知素子を
示す要部破断斜視図FIG. 5 is a fragmentary perspective view showing a gas detecting element of a conventional catalytic combustion gas sensor.
1 測温抵抗体 2 担体 3 触媒 D ガス検知素子 C 補償素子 R1 抵抗 R2 抵抗 E 電源 W 負荷 1 resistance temperature detector 2 carrier 3 catalyst D gas detection element C compensation element R1 resistance R2 resistance E power supply W load
───────────────────────────────────────────────────── フロントページの続き (72)発明者 津田 孝一 神奈川県川崎市川崎区田辺新田1番1号 富士電機株式会社内 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichi Tsuda 1-1-1, Tanabe Shinda, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Fuji Electric Co., Ltd.
Claims (6)
くともパラジウムを含むガスセンサ用触媒の活性化処理
方法において、前記触媒を可燃性ガスおよび水蒸気を含
む空気中で行う第1の熱処理と、その後さらに乾燥空気
中で行う第2の熱処理を行うことを特徴とするガスセン
サ用触媒の活性化処理方法。1. A method for activating a catalyst for a gas sensor, which is supported on a carrier made of a metal oxide and contains at least palladium, in which a first heat treatment is carried out in the air containing a combustible gas and water vapor, and thereafter. A method for activating a catalyst for a gas sensor, further comprising performing a second heat treatment performed in dry air.
〜2%含み、露点が30℃以下の水蒸気を含む空気を4
00ないし500℃に昇温した雰囲気中で、5時間以上
行うことを特徴とする請求項1に記載のガスセンサ用触
媒の活性化処理方法。2. The first heat treatment uses methane gas at 0.5.
4% of air containing ~ 2% and water vapor with dew point below 30 ° C
The method for activating a catalyst for a gas sensor according to claim 1, wherein the method is performed in an atmosphere heated to 00 to 500 ° C. for 5 hours or more.
500℃の乾燥空気中で、2時間以上行うことを特徴と
する請求項1に記載のガスセンサ用触媒の活性化処理方
法。3. The method for activating a catalyst for a gas sensor according to claim 1, wherein the second heat treatment is performed in dry air at a temperature of 400 to 500 ° C. for 2 hours or more.
スズであることを特徴とする請求項1に記載のガスセン
サ用触媒の活性化処理方法。4. The activation treatment method for a gas sensor catalyst according to claim 1, wherein the metal oxide is γ-alumina or tin oxide.
特徴とする請求項1に記載のガスセンサ用触媒の活性化
処理方法。5. The method for activating a catalyst for a gas sensor according to claim 1, wherein the catalyst is palladium and platinum.
くともパラジウムを含むガスセンサ用触媒において、前
記パラジウムの形態は水酸化パラジウムが酸化された酸
化パラジウムであることを特徴とするガスセンサ用触
媒。6. A catalyst for a gas sensor, which is supported on a carrier made of a metal oxide and contains at least palladium, wherein the form of the palladium is palladium oxide in which palladium hydroxide is oxidized.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4021096A JPH09229890A (en) | 1996-02-28 | 1996-02-28 | Catalyst for gas sensor and activation processing method for the catalyst |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4021096A JPH09229890A (en) | 1996-02-28 | 1996-02-28 | Catalyst for gas sensor and activation processing method for the catalyst |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09229890A true JPH09229890A (en) | 1997-09-05 |
Family
ID=12574424
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP4021096A Pending JPH09229890A (en) | 1996-02-28 | 1996-02-28 | Catalyst for gas sensor and activation processing method for the catalyst |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH09229890A (en) |
-
1996
- 1996-02-28 JP JP4021096A patent/JPH09229890A/en active Pending
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Cabot et al. | Analysis of the catalytic activity and electrical characteristics of different modified SnO2 layers for gas sensors | |
Kanchana et al. | EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid | |
CN106990142A (en) | A kind of NO based on graphene/tin dioxide quantal-point composite2Sensor and preparation method thereof | |
JP2887784B2 (en) | Meat freshness measuring device using gas sensor, measuring method thereof and gas sensor manufacturing method | |
JP3624928B2 (en) | Method for producing catalyst for gas sensor | |
JPH09229890A (en) | Catalyst for gas sensor and activation processing method for the catalyst | |
JPH09318582A (en) | Activation treatment of catalyst for gas detection element | |
CN110702752A (en) | Manufacturing method of gas sensor for ammonia gas detection | |
JP3486797B2 (en) | Activation method of catalyst for gas sensor | |
CN112986340B (en) | Thick film material for acetone gas sensitive element, preparation method and acetone gas sensitive element | |
JP3589384B2 (en) | Carbon monoxide sensor and its aging method | |
JPWO2010095630A1 (en) | Electrochemical determination of hydrogen peroxide | |
JP5134599B2 (en) | Catalyst for CO gas sensor, paste, and CO gas sensor | |
Wulandari et al. | A novel non-enzymatic electrochemical uric acid sensing method based on nanohydroxyapatite from eggshell biowaste immobilized on a zinc oxide nanoparticle modified activated carbon electrode (Hap-Esb/ZnONPs/ACE) | |
JPH1114579A (en) | Contact combustion type carbon monoxide sensor | |
Torvela et al. | Dual response of tin dioxide gas sensors characteristic of gaseous carbon tetrachloride | |
CN109387552B (en) | Copper-based porous carbon microsphere composite material and preparation method and application thereof | |
JP3171663B2 (en) | Semiconductor type odor gas sensor | |
CN110133058A (en) | The La of the high air-sensitive selectivity of a kind of pair of acetic acid gas adulterates NiGa2O4Nanocomposite | |
JPS60205348A (en) | Detector for gas component | |
Afonja et al. | Gas sensing properties of composite tungsten trioxide-zeolite thick films | |
CN115924959A (en) | Hydrogen sulfide gas sensitive material and preparation method of hydrogen sulfide gas sensor | |
JPS61223644A (en) | Gaseous hydrogen detecting element and its production | |
JPH058984B2 (en) | ||
JPH04330943A (en) | Photocatalyst and its production |