JP3825216B2 - Exhaust gas treatment method and catalyst-carrying ceramic filter - Google Patents
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Description
【発明の属する技術分野】
本発明は排ガスの処理方法および触媒担持セラミックフィルターに関し、詳しくは焼却炉からの排ガス中に含まれるダイオキシンなどの有害物質を長期にわたり安定して除去し得るようにした排ガスの処理方法、および焼却炉からの排ガスの処理に使用するに好適な触媒担持セラミックフィルターに関する。
【従来の技術】
既設の焼却炉の多くは、焼却炉からの排ガスを電気集塵器またはサイクロンで処理して除塵した後、大気中に放出するタイプのものである。しかし、除塵処理しただけの排ガス中にはダイオキシンなどの有害物質（本発明ではダイオキシン類という。）が含まれており、社会的に重大な問題となっている。ダイオキシン類の除去については効果的な方法が開発されており、これら新規技術を採用した焼却炉を新設することによりダイオキシン類の問題はかなり解決することができる。しかし、直ちに既存の焼却炉を取り壊して、新規技術を採用した焼却炉を新設することは経済的に困難である。このため、既存の焼却設備を利用し、大幅な改造工事を行うことなく、ダイオキシン類の問題を解決できるようにすることが望まれている。
【発明が解決しようとする課題】
本発明は、焼却炉と電気集塵器またはサイクロンとからなる既存の焼却設備を低コストで改造し、ダイオキシン類の排出を効果的に防止し得るようにした、排ガスの処理方法、およびこの処理方法に使用するのに好適な触媒構造体としての触媒担持セラミックフィルターを提供しようとするものである。
【課題を解決するための手段】
本発明者らの研究により次のことがわかった。
（１）電気集塵器またはサイクロンの後に触媒層を設置することによりダイオキシン類を効果的に除去できる。
（２）電気集塵器またはサイクロンの集塵効率は悪いのでダストの除去が不十分である。触媒層では、ガス状のダイオキシン類は分解できるが、ダスト中に含まれるダイオキシン類や粒子状のダイオキシン類は除去することができない。ダイオキシン類は、通常、ダスト、粒子状、ガス状のものを合わせて測定する。このため、結果として、十分に高いダイオキシン類除去率を得ることができないことになる。
（３）電気集塵器またはサイクロンの代わりにバグフィルターを設置することも考えられるが、転換工事に多大のコストがかかる。バグフィルターは集塵効率が高いためダスト、粒子状のダイオキシン類の大部分は除去できるが、バグフィルターの運転温度は低いため、触媒層でのダイオキシン類の十分な分解のためには、触媒量を増加させる必要があり、結果として経済的に不利となる。また、運転温度が低いがために、排ガスに硫黄酸化物が含まれることになり、これが触媒劣化の問題を引き起こすことになる。なお、バグフィルターで処理した排ガスを加熱して触媒層に導入することも考えられるが、加熱がコストアップにつながる。
（４）電気集塵器またはサイクロンの後にセラミックフィルターを設けて除塵効率を高め、排ガス中のダストを十分除去した後に触媒層に導入することにより排ガス中のダイオキシン類を効果的に除去することができる。また、触媒層の耐久性を高めることができる。
（５）セラミックフィルターに触媒を担持して排ガスを処理すると、セラミックフィルターで除塵処理した後、触媒層に接触させる場合と同様の効果が得られる。
本発明は上記知見に基づいて完成されたものである。すなわち、本発明は、焼却炉の排ガスを、電気集塵器またはサイクロンで除塵処理した後、触媒担持セラミックフィルターと接触させることを特徴とする排ガスの処理方法である。また、本発明は、セラミックフィルターに下記触媒（１）を担持したことを特徴とする触媒担持セラミックフィルターである。
＜触媒（１）＞
（ａ）チタン酸化物、（ｂ）バナジウム酸化物、（ｃ）モリブデン酸化物および（ｄ）チタン−ケイ素複合酸化物を含有し、０．０１〜０．０５μｍおよび０．８〜４μｍの範囲にピークを有する細孔径分布を示す触媒。
【発明の実施の形態】
図１は本発明の方法の系統図である。図１において、１は焼却炉、２は電気集塵器（またはサイクロン）、３は触媒担持セラミックフィルター、４は煙突を示す。本発明の方法によれば、焼却炉１からの排ガスを、電気集塵器２に導入して集塵処理を行った後、触媒担持セラミックフィルター６で処理して排ガス中のダイオキシン類を分解除去する。触媒担持セラミックフィルターは、ダイオキシン類分解触媒をセラミックフィルターに担持することにより容易に得られる。セラミックフィルターとしては、ダストの除去に一般に用いられているセラミックフィルターを用いることができる。材質としては、ムライト、ＳｉＣ、コージェライトなど、５００℃以上の耐熱性を有するものが好適に用いられる。形状については特に制限はないが、ろ過面積が大きく、圧力損失の少ないハニカム形状が好ましい。また、電気集塵器の後流側に設置するため、微細粒子（０．１μｍ程度）の集塵効率が９０％以上のものが好適である。
触媒（１）を詳しく説明すると次のとおりである。なお、触媒（１）における細孔径分布は水銀圧入式ポリシメータを用いて測定したものである。
＜触媒（１）＞
（ａ）チタン酸化物、（ｂ）バナジウム酸化物、（ｃ）モリブデン酸化物および（ｄ）チタン−ケイ素複合酸化物を含有し、０．０１〜０．０５μｍおよび０．８〜４μｍの範囲にピークを有する細孔径分布を示す触媒。
なかでも、全細孔容積が０．２〜０．６ｃｃ／ｇであり、０．０１〜０．０５μｍの範囲の細孔群の細孔容積が全細孔容積の２０〜８０％であり、０．８〜４μｍの範囲の細孔群の細孔容積が全細孔容積の５〜７０％である触媒が好ましい。また、成分（ｃ）がモリブデン酸化物である。成分（ｂ）の含有量は、成分（ａ）の０．１〜２５質量％であり、成分（ｃ）の含有量は、成分（ａ）の０．１〜２５質量％であり、成分（ｄ）の含有量は成分（ａ）の０．０１〜７質量倍である。平均粒子径は０．００１〜１００μｍ、好ましくは０．０１〜１００μｍである。また、ＢＥＴ法による比表面積は３０〜２５０ｍ２／ｇ、好ましくは４０〜２００ｍ２／ｇである。
触媒（１）は、触媒活性成分として成分（ａ）〜（ｄ）を含有させる点を除けば、この種の触媒に一般に用いられている方法にしたがって調製することができる。また、上記細孔径分布を有する触媒も、（１）触媒調製時にデンプンなどの成型助剤や水分の添加量を調整する、（２）触媒焼成時に分解または揮発する樹脂を混練り時に添加する、などの従来公知の方法によって容易に得ることができる。
本発明の触媒担持セラミックフィルターは、例えば、次のように調製することができる。
（１）触媒を粉砕した後、水に分散してスラリー状にする。このスラリー溶液にセラミックフィルターを浸漬して、触媒成分を担持した後、乾燥、焼成する。
（２）水に各触媒成分の水溶性塩を溶解し、均一混合溶液を調製する。この溶液にセラミックフィルターを浸漬して、触媒成分を含浸担持した後、乾燥、焼成する。
（３）チタン酸化物またはチタン−ケイ素複合酸化物をセラミックフィルターに担持した後、乾燥、焼成し、次いでこのセラミックフィルターにバナジウムや他の金属成分を含む溶液を含浸担持した後、乾燥、焼成する。触媒の担持量は、セラミックフィルターの質量に対し、通常、１〜２０質量％であり、好ましくは２〜１５質量％である。担持量が多すぎるとセラミックフィルターの気孔率が低下し、圧力損失が大きくなる。一方、担持量が少なすぎると十分な触媒活性が得られない。
電気集塵器２および触媒担持セラミックフィルター３の運転条件については特に制限はなく、排ガスの温度、性状、要求される除去性能などを考慮して適宜決定することができる。触媒担持セラミックフィルターの使用温度は、電気集塵器２で集塵処理した後の排ガスは、通常、そのまま触媒担持セラミックフィルター３に導入するので、一般に採用されている電気集塵器の運転温度範囲内で適宜決定することができ、好ましくは２００℃以上４５０℃未満である。触媒担持セラミックフィルター３での排ガスの空間速度は、通常、１００〜１００，０００ｈ−１（ＳＴＰ）、好ましくは２００〜５０，０００ｈ−１（ＳＴＰ）である。
本発明のダイオキシン類とは、一般にダイオキシンといわれるものであり、具体的には、ポリハロゲン化ジベンゾパラダイオキシン、ポリハロゲン化ジベンゾフラン、ポリハロゲン化ビフェニルなどを挙げることができる。
なお、本発明の触媒担持セラミックフィルターは、ダスト中に含まれるダイオキシン類や粒子状のダイオキシン類を除去すると同時に、ガス状のダイオキシン類の分解活性に優れ、これらダイオキシン類を含む産業廃棄物や都市廃棄物を処理する焼却施設から発生する排ガスの処理に好適に用いられる。
【発明の効果】
本発明の主たる効果を列挙すると次のとおりである。
（１）電気集塵器またはサイクロンを備えた既設の焼却炉に触媒担持セラミックフィルターを設置するだけで排ガス中のダイオキシン類を効果的に除去することができる。
（２）既設の焼却施設の改造を低コストで行うことができる。
（３）セラミックフィルターは耐熱性があるため、高温域で運転可能であり、そのため、排ガスを高温で触媒層に導入できるので、触媒の分解効率が高まると同時に除塵も行えるのでダイオキシン類の除去効率が一段と向上し、結果的に出口ダイオキシン類の濃度を０．１ｎｇ−ＴＥＱ／ｍ３以下の低濃度まで低減することができる。
（４）排ガス中のダイオキシン類を長期にわたり安定して除去することができる。
【実施例】
以下、実施例を挙げて本発明を更に具体的に説明する。
（実施例１）
１０質量％アンモニア水７００リットルにスノーテックス−２０（日産化学（株）製シリカゾル、約２０質量％のＳｉＯ２含有）２１．３ｋｇを加え、攪拌、混合した後、硫酸チタニルの硫酸溶液（ＴｉＯ２として１２５ｇ／リットル、硫酸濃度０．５５ｇ／リットル）３４０リットルを攪拌しながら徐々に滴下した。得られたゲルを３時間放置した後、ろ過、水洗し、続いて１５０℃で１０時間乾燥した。これを５００℃で焼成し、さらにハンマーミルを用いて粉砕し、分級機で分級して平均粒子径１０μｍの粉体を得た。得られた粉体の組成はＴｉＯ２：ＳｉＯ２＝８．５：１．５（モル比）であり、粉体のＸ線回折チャートではＴｉＯ２やＳｉＯ２の明らかな固有のピークは認められず、ブロードな回折ピークによって非晶質な微細構造を有するチタンとケイ素との複合酸化物（Ｔｉ−Ｓｉ複合酸化物）であることが確認された。上記Ｔｉ−Ｓｉ複合酸化物９ｋｇおよび市販の酸化チタン粉体（ＤＴ−５１（商品名）、ミレニアム社製）９ｋｇに、メタバナジン酸アンモニウム１．２９ｋｇおよびシュウ酸１．６８ｋｇを水５リットルに溶解させた溶液と、パラモリブデン酸アンモニウム１．２３ｋｇおよびモノエタノールアミン０．４３ｋｇを水３リットルに溶解させた溶液とを加え、さらにフェノール樹脂（ベルバール（商品名）、カネボウ（株）製）０．９ｋｇと成形助剤としてのデンプン０．４５ｋｇとを加えて混合し、ニーダーで混練りした後、押出成形機で５ｍｍφｘ５ｍｍＬのペレット状に成形した。次いで、８０℃で乾燥した後、４５０℃で５時間空気雰囲気下で焼成した触媒を得た。この触媒の組成は、Ｖ２Ｏ５：ＭｏＯ３：ＴｉＯ２：Ｔｉ−Ｓｉ複合酸化物＝５：５：４５：４５（質量％）であった。また、この触媒の細孔径分布を水銀圧入式ポロシメータにより測定した結果、全細孔容積は０．３７ｃｃ／ｇであった。また、０．０１〜０．０５μｍの範囲に細孔径分布のピークを有する細孔群の細孔容積および０．８〜４μｍの範囲に細孔径分布のピークを有する細孔群の細孔容積は、それぞれ、全細孔容積の５５％および２０％であった。ＢＥＴ比表面積は７３ｍ２／ｇであった。次に、上記触媒をハンマーミルを用いて粉砕し、この粉体２．５ｋｇを１０リットルの水に投入し、よく攪拌してスラリー状の溶液を調製した。このスラリー溶液にコージェライトハニカム型セラミックフィルター（目開き９ｍｍ、肉厚１ｍｍ、集塵効率９９％）を浸漬した。余分なスラリーを除去した後、６０℃で乾燥し、空気雰囲気下５００℃で焼成して触媒担持セラミックフィルター（１）を得た。このときの触媒の担持量はセラミックフィルターの質量に対し１０質量％であった。
（実施例２）
図１に示すように、電気集塵器の出口側（ダイオキシン類濃度：１ｎｇ−ＴＥＱ／ｍ３）に触媒担持セラミックフィルター（１）を設置し排ガスの処理を行った。初期性能、２，０００時間、５，０００時間、１０，０００時間後のダイオキシン類除去率および出口ダイオキシン類濃度を表１に示す。
空間速度：２，０００ｈ−１
反応温度：２５０〜３５０℃
なお、ダイオキシン類除去率は次の式にしたがって求めた。
ダイオキシン類除去率（％）＝［（触媒担持セラミックフィルター入口ダイオキシン類濃度−触媒担持セラミックフィルター出口ダイオキシン類濃度）／（触媒担持セラミックフィルター入口ダイオキシン類濃度）］×１００
（比較例１）
実施例２において、触媒担持セラミックフィルター（１）の代わりに実施例１で使用したセラミックフィルターを、触媒成分を担持しないで、２５０℃で使用した場合のダイオキシン類除去率は１５％であった。また、その時の出口ダイオキシン類濃度は０．８５ｎｇ−ＴＥＱ／ｍ３であった。
（比較例２）
実施例２において、触媒担持セラミックフィルター（１）の代わりに下記方法により調製した触媒で、目開き９ｍｍ、肉厚１ｍｍのハニカム状に成形した以外は同様の方法で調製した触媒のみを用いて、２５０℃でのダイオキシン類の除去率を測定した。初期性能、２，０００時間、５，０００時間、１０，０００時間後のダイオキシン類除去率および出口ダイオキシン類濃度を表１に示す。
＜方法＞
市販の酸化チタン粉体（ＤＴ−５１（商品名）、ミレニアム社製）１８ｋｇに、メタバナジン酸アンモニウム１．２９ｋｇおよびシュウ酸１．６８ｋｇを水５リットルに溶解させた溶液と、パラモリブデン酸アンモニウム１．２３ｋｇおよびモノエタノールアミン０．４３ｋｇを水３リットルに溶解させた溶液とを加え、さらにフェノール樹脂（ベルバール（商品名）、カネボウ（株）製）０．９ｋｇと成形助剤としてのデンプン０．４５ｋｇとを加えて混合し、ニーダーで混練りした後、押出成形機で５ｍｍφｘ５ｍｍＬのペレット状に成形した。次いで、８０℃で乾燥した後、４５０℃で５時間空気雰囲気下で焼成した触媒を得た。この触媒の組成は、Ｖ２Ｏ５：ＭｏＯ３：ＴｉＯ２＝５：５：９０（質量％）であった。また、この触媒（１）の細孔径分布を水銀圧入式ポロシメータにより測定した結果、全細孔容積は０．３９ｃｃ／ｇであった。また、０．０１〜０．０５μｍの範囲に細孔径分布のピークを有する細孔群の細孔容積および０．１〜０．８μｍの範囲に細孔径分布のピークを有する細孔群の細孔容積は、それぞれ、全細孔容積の３７％および５４％であった。ＢＥＴ比表面積は７３ｍ２／ｇであった。
【表１】
【図面の簡単な説明】
【図１】 本発明の方法の系統図である。BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to an exhaust gas treatment method and a catalyst-carrying ceramic filter, and more particularly to an exhaust gas treatment method and an incinerator capable of stably removing harmful substances such as dioxin contained in the exhaust gas from the incinerator over a long period of time. The present invention relates to a catalyst-supporting ceramic filter that is suitable for use in the treatment of exhaust gas from water.
[Prior art]
Many of the existing incinerators are of a type in which the exhaust gas from the incinerator is treated with an electric dust collector or a cyclone to remove the dust and then released into the atmosphere. However, harmful substances such as dioxins (referred to as dioxins in the present invention) are contained in the exhaust gas that has been subjected to dust removal treatment, which is a serious social problem. Effective methods have been developed for the removal of dioxins, and the problem of dioxins can be considerably solved by newly installing an incinerator employing these new technologies. However, it is economically difficult to immediately demolish an existing incinerator and establish a new incinerator employing new technology. For this reason, it is desired to use existing incineration facilities and to be able to solve the problem of dioxins without carrying out a major remodeling work.
[Problems to be solved by the invention]
The present invention relates to a method for treating exhaust gas, and an existing incineration facility comprising an incinerator and an electrostatic precipitator or cyclone, which can be modified at low cost, and can effectively prevent dioxins from being discharged, and this treatment It is intended to provide a catalyst-supported ceramic filter as a catalyst structure suitable for use in the process.
[Means for Solving the Problems]
The following has been found by the inventors' research.
(1) Dioxins can be effectively removed by installing a catalyst layer after the electrostatic precipitator or cyclone.
(2) Since the dust collection efficiency of the electric dust collector or cyclone is poor, the removal of dust is insufficient. In the catalyst layer, gaseous dioxins can be decomposed, but dioxins and particulate dioxins contained in dust cannot be removed. Dioxins are usually measured by combining dust, particles, and gas. For this reason, as a result, a sufficiently high dioxin removal rate cannot be obtained.
(3) Although it is conceivable to install a bag filter in place of the electrostatic precipitator or the cyclone, the conversion work is very expensive. Bag filters have high dust collection efficiency, so most of dust and particulate dioxins can be removed. However, since the operating temperature of bag filters is low, the amount of catalyst is sufficient for sufficient decomposition of dioxins in the catalyst layer. As a result, it is economically disadvantageous. Moreover, since the operating temperature is low, sulfur oxide is contained in the exhaust gas, which causes a problem of catalyst deterioration. Although it is conceivable to heat the exhaust gas treated with the bag filter and introduce it into the catalyst layer, heating leads to an increase in cost.
(4) It is possible to effectively remove dioxins in the exhaust gas by providing a ceramic filter after the electrostatic precipitator or cyclone to improve the dust removal efficiency and sufficiently removing the dust in the exhaust gas and then introducing it into the catalyst layer. it can. Further, the durability of the catalyst layer can be increased.
(5) When the catalyst is supported on the ceramic filter and the exhaust gas is treated, the same effect as that obtained when the dust is treated with the ceramic filter and then brought into contact with the catalyst layer can be obtained.
The present invention has been completed based on the above findings. That is, the present invention is a method for treating exhaust gas, wherein the exhaust gas from the incinerator is subjected to dust removal treatment with an electric dust collector or a cyclone and then brought into contact with a catalyst-supporting ceramic filter. The present invention also provides a catalyst-carrying ceramic filter characterized in that the following catalyst (1) is carried on a ceramic filter.
<Catalyst (1)>
(A) titanium oxide, (b) vanadium oxide, (c) molybdenum oxide, and (d) titanium-silicon composite oxide, in the range of 0.01 to 0.05 μm and 0.8 to 4 μm A catalyst showing a pore size distribution having a peak.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram of the method of the present invention. In FIG. 1, 1 is an incinerator, 2 is an electric dust collector (or cyclone), 3 is a catalyst-supporting ceramic filter, and 4 is a chimney. According to the method of the present invention, the exhaust gas from the incinerator 1 is introduced into the electrostatic precipitator 2 for dust collection, and then treated with the catalyst-supporting ceramic filter 6 to decompose and remove dioxins in the exhaust gas. To do. A catalyst-supporting ceramic filter can be easily obtained by supporting a dioxin decomposition catalyst on a ceramic filter. As the ceramic filter, a ceramic filter generally used for dust removal can be used. As the material, a material having a heat resistance of 500 ° C. or higher such as mullite, SiC, cordierite, etc. is preferably used. The shape is not particularly limited, but a honeycomb shape having a large filtration area and a small pressure loss is preferable. Further, since it is installed on the downstream side of the electric dust collector, it is preferable that the dust collection efficiency of fine particles (about 0.1 μm) is 90% or more.
The catalyst (1) will be described in detail as follows. The pore size distribution in the catalyst (1) was measured using a mercury intrusion polysimeter.
<Catalyst (1)>
(A) titanium oxide, (b) vanadium oxide, (c) molybdenum oxide, and (d) titanium-silicon composite oxide, in the range of 0.01 to 0.05 μm and 0.8 to 4 μm A catalyst showing a pore size distribution having a peak.
Among them, the total pore volume is 0.2 to 0.6 cc / g, the pore volume of the pore group in the range of 0.01 to 0.05 μm is 20 to 80% of the total pore volume, A catalyst in which the pore volume of the pore group in the range of 0.8 to 4 μm is 5 to 70% of the total pore volume is preferable. Component (c) is molybdenum oxide. The content of the component (b) is 0.1 to 25% by mass of the component (a), the content of the component (c) is 0.1 to 25% by mass of the component (a), and the component ( Content of d) is 0.01-7 mass times of a component (a). The average particle size is 0.001 to 100 μm, preferably 0.01 to 100 μm. In addition, the specific surface area by BET method 30~250m 2 / g, preferably from 40 to 200 m 2 / g.
The catalyst (1) can be prepared according to a method generally used for this type of catalyst except that the components (a) to (d) are contained as catalytic active components. Further, the catalyst having the pore size distribution is also (1) adjusting the amount of molding aid such as starch and water added at the time of catalyst preparation, (2) adding a resin that decomposes or volatilizes at the time of catalyst firing, It can be easily obtained by a conventionally known method such as
The catalyst-carrying ceramic filter of the present invention can be prepared, for example, as follows.
(1) After pulverizing the catalyst, it is dispersed in water to form a slurry. A ceramic filter is immersed in this slurry solution to support the catalyst component, and then dried and fired.
(2) A water-soluble salt of each catalyst component is dissolved in water to prepare a uniform mixed solution. A ceramic filter is immersed in this solution to impregnate and support the catalyst component, and then dried and fired.
(3) After supporting titanium oxide or titanium-silicon composite oxide on a ceramic filter, drying and firing, and then impregnating and supporting a solution containing vanadium and other metal components on this ceramic filter, drying and firing. . The supported amount of the catalyst is usually 1 to 20% by mass, preferably 2 to 15% by mass with respect to the mass of the ceramic filter. If the amount is too large, the porosity of the ceramic filter is lowered and the pressure loss is increased. On the other hand, if the supported amount is too small, sufficient catalytic activity cannot be obtained.
The operating conditions of the electrostatic precipitator 2 and the catalyst-carrying ceramic filter 3 are not particularly limited, and can be appropriately determined in consideration of the exhaust gas temperature, properties, required removal performance, and the like. As for the operating temperature of the catalyst-carrying ceramic filter, the exhaust gas after dust collection by the electrostatic precipitator 2 is usually introduced directly into the catalyst-carrying ceramic filter 3, so that the operating temperature range of the commonly used electrostatic precipitator It can be suitably determined within the range, and is preferably 200 ° C. or higher and lower than 450 ° C. The space velocity of the exhaust gas at the catalyst-carrying ceramic filter 3, usually, 100~100,000h -1 (STP), preferably 200~50,000h -1 (STP).
The dioxins of the present invention are generally referred to as dioxins, and specific examples include polyhalogenated dibenzoparadioxins, polyhalogenated dibenzofurans, and polyhalogenated biphenyls.
The catalyst-carrying ceramic filter of the present invention removes dioxins and particulate dioxins contained in dust, and at the same time, is excellent in the decomposition activity of gaseous dioxins, and industrial waste and urban containing these dioxins. It is suitably used for the treatment of exhaust gas generated from an incineration facility that treats waste.
【The invention's effect】
The main effects of the present invention are listed as follows.
(1) Dioxins in exhaust gas can be effectively removed simply by installing a catalyst-supporting ceramic filter in an existing incinerator equipped with an electric dust collector or cyclone.
(2) The existing incineration facility can be modified at low cost.
(3) Since ceramic filters are heat resistant, they can be operated at high temperatures. Therefore, exhaust gas can be introduced into the catalyst layer at high temperatures, so that the decomposition efficiency of the catalyst can be increased and the dust can be removed. As a result, the concentration of the outlet dioxins can be reduced to a low concentration of 0.1 ng-TEQ / m 3 or less.
(4) Dioxins in exhaust gas can be stably removed over a long period of time.
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1
After adding 21.3 kg of SNOWTEX-20 (silica sol manufactured by Nissan Chemical Co., Ltd., containing about 20% by mass of SiO 2 ) to 700 L of 10% by mass ammonia water, stirring and mixing, a sulfuric acid solution of titanyl sulfate (TiO 2) As a result, 340 liters of 125 g / liter, sulfuric acid concentration 0.55 g / liter) was gradually added dropwise with stirring. The obtained gel was allowed to stand for 3 hours, filtered, washed with water, and then dried at 150 ° C. for 10 hours. This was fired at 500 ° C., further pulverized using a hammer mill, and classified by a classifier to obtain a powder having an average particle diameter of 10 μm. The composition of the obtained powder was TiO 2 : SiO 2 = 8.5: 1.5 (molar ratio), and clear intrinsic peaks of TiO 2 and SiO 2 were recognized in the X-ray diffraction chart of the powder. In addition, it was confirmed by a broad diffraction peak that it was a composite oxide of titanium and silicon (Ti-Si composite oxide) having an amorphous microstructure. To 9 kg of the above Ti-Si composite oxide and 9 kg of commercially available titanium oxide powder (DT-51 (trade name), manufactured by Millennium), 1.29 kg of ammonium metavanadate and 1.68 kg of oxalic acid were dissolved in 5 liters of water. And a solution obtained by dissolving 1.23 kg of ammonium paramolybdate and 0.43 kg of monoethanolamine in 3 liters of water, and 0.9 kg of phenol resin (Belbar (trade name), manufactured by Kanebo Co., Ltd.) And 0.45 kg of starch as a molding aid were added and mixed, kneaded with a kneader, and then molded into pellets of 5 mmφ × 5 mmL with an extruder. Subsequently, after drying at 80 degreeC, the catalyst which baked in the air atmosphere at 450 degreeC for 5 hours was obtained. The composition of this catalyst was V 2 O 5 : MoO 3 : TiO 2 : Ti—Si composite oxide = 5: 5: 45: 45 (mass%). Moreover, as a result of measuring the pore size distribution of this catalyst with a mercury intrusion porosimeter, the total pore volume was 0.37 cc / g. The pore volume of the pore group having a peak of pore diameter distribution in the range of 0.01 to 0.05 μm and the pore volume of the pore group having a peak of pore diameter distribution in the range of 0.8 to 4 μm are Respectively, 55% and 20% of the total pore volume. The BET specific surface area was 73 m 2 / g. Next, the catalyst was pulverized using a hammer mill, and 2.5 kg of the powder was put into 10 liters of water and stirred well to prepare a slurry solution. A cordierite honeycomb type ceramic filter (aperture 9 mm, wall thickness 1 mm, dust collection efficiency 99%) was immersed in this slurry solution. After removing the excess slurry, the slurry was dried at 60 ° C. and fired at 500 ° C. in an air atmosphere to obtain a catalyst-supporting ceramic filter (1). The amount of the catalyst supported at this time was 10% by mass with respect to the mass of the ceramic filter.
(Example 2)
As shown in FIG. 1, a catalyst-supporting ceramic filter (1) was installed on the outlet side of the electrostatic precipitator (dioxins concentration: 1 ng-TEQ / m 3 ) to treat the exhaust gas. Table 1 shows the initial performance, dioxins removal rate and outlet dioxins concentration after 2,000 hours, 5,000 hours, and 10,000 hours.
Space velocity: 2,000h -1
Reaction temperature: 250-350 ° C
The dioxin removal rate was determined according to the following formula.
Dioxins removal rate (%) = [(Catalyst-supported ceramic filter inlet dioxins concentration−Catalyst-supported ceramic filter outlet dioxins concentration) / (Catalyst-supported ceramic filter inlet dioxins concentration)] × 100
(Comparative Example 1)
In Example 2, the dioxin removal rate when the ceramic filter used in Example 1 instead of the catalyst-carrying ceramic filter (1) was used at 250 ° C. without carrying a catalyst component was 15%. Moreover, the exit dioxin density | concentration at that time was 0.85 ng-TEQ / m < 3 >.
(Comparative Example 2)
In Example 2, instead of the catalyst-carrying ceramic filter (1), only the catalyst prepared by the same method except that the catalyst was prepared by the following method and formed into a honeycomb shape having an opening of 9 mm and a wall thickness of 1 mm, The removal rate of dioxins at 250 ° C. was measured. Table 1 shows the initial performance, dioxins removal rate and outlet dioxins concentration after 2,000 hours, 5,000 hours, and 10,000 hours.
<Method>
A solution obtained by dissolving 1.29 kg of ammonium metavanadate and 1.68 kg of oxalic acid in 5 liters of water in 18 kg of commercially available titanium oxide powder (DT-51 (trade name), manufactured by Millennium), and ammonium paramolybdate 1 .23 kg and a solution obtained by dissolving 0.43 kg of monoethanolamine in 3 liters of water, 0.9 kg of phenol resin (Belbar (trade name), manufactured by Kanebo Co., Ltd.) and starch as a molding aid 0. 45 kg was added and mixed, kneaded with a kneader, and then molded into pellets of 5 mmφ × 5 mmL with an extruder. Subsequently, after drying at 80 degreeC, the catalyst which baked in the air atmosphere at 450 degreeC for 5 hours was obtained. The composition of this catalyst was V 2 O 5 : MoO 3 : TiO 2 = 5: 5: 90 (mass%). Moreover, as a result of measuring the pore size distribution of the catalyst (1) with a mercury intrusion porosimeter, the total pore volume was 0.39 cc / g. Further, the pore volume of the pore group having a peak of pore diameter distribution in the range of 0.01 to 0.05 μm and the pore of the pore group having a peak of pore diameter distribution in the range of 0.1 to 0.8 μm The volumes were 37% and 54% of the total pore volume, respectively. The BET specific surface area was 73 m 2 / g.
[Table 1]
[Brief description of the drawings]
FIG. 1 is a system diagram of the method of the present invention.
Claims (4)
＜触媒（１）＞
（ａ）チタン酸化物、（ｂ）バナジウム酸化物、（ｃ）モリブデン酸化物および（ｄ）チタン−ケイ素複合酸化物を含有し、０．０１〜０．０５μｍおよび０．８〜４μｍの範囲にピークを有する細孔分布を示す触媒。A ceramic filter for removing dioxins characterized by supporting the following catalyst (1) on a ceramic filter.
<Catalyst (1)>
(A) titanium oxide, (b) vanadium oxide, (c) molybdenum oxide, and (d) titanium-silicon composite oxide, in the range of 0.01 to 0.05 μm and 0.8 to 4 μm A catalyst showing a pore distribution with a peak.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP37412899A JP3825216B2 (en) | 1999-12-28 | 1999-12-28 | Exhaust gas treatment method and catalyst-carrying ceramic filter |
| TW089127567A TW565470B (en) | 1999-12-28 | 2000-12-21 | Process for disposing of exhaust gases |
| US09/740,971 US6716404B2 (en) | 1999-12-28 | 2000-12-21 | Process for the purification of exhaust gases |
| DE60034207T DE60034207T2 (en) | 1999-12-28 | 2000-12-22 | Process for the removal of exhaust gases |
| EP00128287A EP1112772B1 (en) | 1999-12-28 | 2000-12-22 | Process for disposing of exhaust gases |
| KR10-2000-0081736A KR100518957B1 (en) | 1999-12-28 | 2000-12-26 | Process for purification of exhaust gases |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP37412899A JP3825216B2 (en) | 1999-12-28 | 1999-12-28 | Exhaust gas treatment method and catalyst-carrying ceramic filter |
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| Application Number | Title | Priority Date | Filing Date |
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| JP2005288013A Division JP2006075834A (en) | 2005-09-30 | 2005-09-30 | Exhaust gas treatment method and catalyst carrying ceramic filter |
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| Publication Number | Publication Date |
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| JP2001187318A JP2001187318A (en) | 2001-07-10 |
| JP3825216B2 true JP3825216B2 (en) | 2006-09-27 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1852184A4 (en) | 2004-12-27 | 2008-02-06 | Ibiden Co Ltd | Ceramic honeycomb structure |
| KR100945311B1 (en) * | 2009-09-04 | 2010-03-03 | 주식회사 무진하이테크 | Visible ray reaction type hybrid photocatalyst filter and air cleaner |
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