JP4246584B2 - Method for purifying ammonia-containing exhaust gas and ammonia-containing wastewater - Google Patents
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
本発明はアンモニア含有排水の浄化方法に関する。 The present invention relates to a method for purifying ammonia-containing wastewater.
アンモニア含有排ガスをアンモニア分解触媒に接触させて排ガス中のアンモニアを窒素ガスと水とに分解して浄化する際、分解後の処理ガス中には未分解アンモニアのほかに、副生する一酸化窒素や二酸化窒素（以下、まとめて「ＮＯｘ」という。）および亜酸化窒素（Ｎ２Ｏ）が含まれている。しかし、これらアンモニア、ＮＯｘおよび亜酸化窒素は環境に対して有害物質であり、これらを含む処理ガスをそのまま大気中に放出することは環境上好ましくない。 When the ammonia-containing exhaust gas is contacted with an ammonia decomposition catalyst to decompose and purify ammonia in the exhaust gas into nitrogen gas and water, the treated gas in addition to undecomposed ammonia is a by-product of nitric oxide. And nitrogen dioxide (hereinafter collectively referred to as “NOx”) and nitrous oxide (N 2 O). However, these ammonia, NOx, and nitrous oxide are harmful substances to the environment, and it is not environmentally preferable to discharge the processing gas containing them into the atmosphere as they are.
上記問題を解決するために、ＮＯｘを残留アンモニアとともに還元触媒に接触させて、窒素ガスと水とに分解することが提案されている（特許文献１参照）。しかし、ここでは亜酸化窒素は除去されず処理後のガス中には亜酸化窒素が残留し、この亜酸化窒素は地球の温暖化やオゾン層破壊に影響を及ぼす有害な物質であることから、環境への悪影響が問題となる。 In order to solve the above problem, it has been proposed that NOx is brought into contact with a reduction catalyst together with residual ammonia to be decomposed into nitrogen gas and water (see Patent Document 1). However, nitrous oxide is not removed here, and nitrous oxide remains in the treated gas. This nitrous oxide is a harmful substance that affects global warming and the destruction of the ozone layer. The negative impact on the environment becomes a problem.
上記亜酸化窒素の生成を防止することを目的として、アンモニア含有排ガスをアンモニア酸化触媒層および窒素酸化還元触媒層からなる二段触媒層に導入し、後段の窒素酸化還元触媒層からの処理ガス中の窒素酸化物濃度を測定し、その窒素酸化物濃度が所定濃度となるように処理ガスの一部を分割して、後段の窒素酸化還元触媒層に注入する方法が提案されている（特許文献２）。 For the purpose of preventing the generation of nitrous oxide, ammonia-containing exhaust gas is introduced into a two-stage catalyst layer comprising an ammonia oxidation catalyst layer and a nitrogen oxidation-reduction catalyst layer, and the treatment gas from the nitrogen oxidation-reduction catalyst layer at the latter stage is introduced. A method has been proposed in which the nitrogen oxide concentration of the gas is measured, a part of the processing gas is divided so that the nitrogen oxide concentration becomes a predetermined concentration, and injected into the subsequent nitrogen redox catalyst layer (Patent Document) 2).
また、上記方法と同様に、アンモニア酸化触媒層および窒素酸化還元触媒層からなる二段触媒層を用い、アンモニア酸化触媒での未反応アンモニア濃度に対し、窒素酸化物濃度が常時５０ｐｐｍ以下となるように前段のアンモニア酸化触媒層の温度を制御する方法が提案されている（特許文献３）。 Similarly to the above method, using a two-stage catalyst layer comprising an ammonia oxidation catalyst layer and a nitrogen oxidation-reduction catalyst layer, the nitrogen oxide concentration is always 50 ppm or less relative to the unreacted ammonia concentration in the ammonia oxidation catalyst. A method of controlling the temperature of the ammonia oxidation catalyst layer in the previous stage has been proposed (Patent Document 3).
特許文献２および３に記載の技術は、前段触媒層で亜酸化窒素ができるだけ生成しないようにアンモニアを分解し、後段触媒層では前段触媒層で副生したＮＯｘを、処理ガスから予め分割注入されたアンモニア、あるいは前段アンモニア酸化触媒層温度を制御することで残留させた未反応アンモニアを利用して亜酸化窒素を生成させないようにバランスよく分解し、プロセス全体として亜酸化窒素を低減しようとするものである。 In the techniques described in Patent Documents 2 and 3, ammonia is decomposed so that nitrous oxide is not generated as much as possible in the preceding catalyst layer, and NOx produced as a by-product in the preceding catalyst layer is dividedly injected from the processing gas in advance in the latter catalyst layer. By using the remaining ammonia or unreacted ammonia remaining by controlling the temperature of the previous stage ammonia oxidation catalyst layer, it is decomposed in a well-balanced manner so as not to generate nitrous oxide, and the entire process is attempted to reduce nitrous oxide. It is.
アンモニア含有排水の浄化に際しては、アンモニア含有排水をストリッピング処理に供し、得られるアンモニア含有排ガスを触媒に接触させてアンモニアを分解することが一般に行われており、このアンモニア含有排ガスの処理に際しても上記のような亜酸化窒素の生成という問題が生じる。 When purifying ammonia-containing wastewater, it is generally carried out by subjecting the ammonia-containing wastewater to stripping treatment and bringing the resulting ammonia-containing exhaust gas into contact with a catalyst to decompose ammonia. The problem of nitrous oxide generation occurs.
そこで、アンモニアを分解するに際して、発生する亜酸化窒素濃度が所定の範囲となるように、触媒層でのガス流量を調整するか、あるいは触媒層でのガスの接触時間を調整する方法が提案されている（特許文献４）。 Therefore, a method for adjusting the gas flow rate in the catalyst layer or adjusting the contact time of the gas in the catalyst layer is proposed so that the concentration of nitrous oxide generated when decomposing ammonia is within a predetermined range. (Patent Document 4).
また、アンモニアを分解するに際して、発生する亜酸化窒素濃度が所定の範囲となるように、触媒層に導入するガス中の酸素濃度を調整する方法が提案されている（特許文献５）。 Further, a method has been proposed in which the oxygen concentration in the gas introduced into the catalyst layer is adjusted so that the generated nitrous oxide concentration falls within a predetermined range when decomposing ammonia (Patent Document 5).
特許文献４および５に記載の技術は、特定組成の触媒からなる一段触媒層を用い、触媒層でのガス流量を調整したり、あるいはガス中の酸素濃度を調整することにより、亜酸化窒素の副生を抑制しながらアンモニアを窒素と水とに分解するというものである。 The techniques described in Patent Documents 4 and 5 use a single-stage catalyst layer composed of a catalyst having a specific composition, adjust the gas flow rate in the catalyst layer, or adjust the oxygen concentration in the gas, thereby reducing nitrous oxide. This is to decompose ammonia into nitrogen and water while suppressing by-products.
前記従来技術のいずれにおいても、亜酸化窒素濃度を低減させるためには、運転条件を厳密に規定する必要があり、またこれを実現するために複雑な制御系が必要である。このため、処理しようとする排ガス中のアンモニアやＮＯｘの濃度が変動したりするときには、応答に遅れが生じて亜酸化窒素が排出される可能性がある。 In any of the above prior arts, in order to reduce the nitrous oxide concentration, it is necessary to strictly define the operating conditions, and a complicated control system is necessary to realize this. For this reason, when the concentration of ammonia or NOx in the exhaust gas to be treated fluctuates, there is a possibility that the response is delayed and nitrous oxide is discharged.
本発明は、アンモニアを含有する排水からアンモニアをストリッピング処理して浄化するに際し、発生するアンモニア含有排ガスを，亜酸化窒素の排出を著しく低減して、効率よく処理する、アンモニア含有排水の浄化方法を提供しようとするものである。 The present invention relates to a method for purifying ammonia-containing wastewater, in which when ammonia is stripped and purified from wastewater containing ammonia, the exhaust gas containing ammonia is efficiently treated by significantly reducing nitrous oxide emissions. Is to provide.
本発明者らの研究によれば、前記目的は下記発明により達成できることがわかった。
アンモニアを含有する排水を下記工程を含むプロセスにしたがって浄化することを特徴とするアンモニア含有排水の浄化方法。
（ａ）アンモニア含有排水をストリッピング処理に供してアンモニアを気相中に移行させる工程。
（ｂ）工程（ａ）からのアンモニア含有排ガスを、Ｃｏ、ＣｅおよびＭｎを含む酸化物触媒および／または酸化物担体とＡｇとＦｅとを含有する触媒に接触させてアンモニアを分解する工程。
（ｃ）工程（ｂ）からの処理ガスをＲｈ担持γ−アルミナ触媒に接触させて処理ガス中の亜酸化窒素を分解する工程。
According to the studies by the present inventors, it has been found that the object can be achieved by the following invention.
A method for purifying ammonia-containing wastewater, comprising purifying wastewater containing ammonia according to a process including the following steps.
(A) step of shifting subjecting the ammonia-containing waste water in the stripped ammonia in the gas phase.
( B ) The step of decomposing ammonia by contacting the ammonia-containing exhaust gas from step ( a ) with an oxide catalyst containing Co, Ce and Mn and / or a catalyst containing an oxide carrier, Ag and Fe.
( C ) A step of bringing the processing gas from step ( b ) into contact with the Rh-supported γ-alumina catalyst to decompose nitrous oxide in the processing gas.
本発明によれば、厳密な運転条件の維持、あるいはこれを実現するための複雑な制御系を設定することなく、アンモニア含有排水を効率よく浄化することができる。 According to the present invention, it is possible to efficiently purify ammonia-containing wastewater without maintaining strict operating conditions or setting a complicated control system for realizing this.
本発明によれば、浄化処理後の排出ガス中に含まれる残留アンモニア、ＮＯｘおよび亜酸化窒素の濃度を環境上問題がない程度まで低減することができる。 According to the present invention, it is possible to reduce the concentrations of residual ammonia, NOx and nitrous oxide contained in the exhaust gas after the purification treatment to such an extent that there is no environmental problem.
また、本発明によれば、処理しようとする排ガス中のアンモニア濃度が変動しても、これに即応して、浄化処理後の排出ガス中の残留アンモニア、ＮＯｘおよび亜酸化窒素の濃度を環境上問題がない程度まで低減することができる。 Further, according to the present invention, even if the ammonia concentration in the exhaust gas to be treated fluctuates, the concentration of residual ammonia, NOx and nitrous oxide in the exhaust gas after the purification treatment is promptly changed in response to this. It can be reduced to the extent that there is no problem.
本発明は、基本的に、（ａ）アンモニア含有排水をストリッピング処理に供してアンモニアを気相中に移行させる工程と、（ｂ）工程（ａ）からのアンモニア含有排ガスを、Ｃｏ、ＣｅおよびＭｎを含む酸化物触媒および／または酸化物担体とＡｇとＦｅとを含有する触媒に接触させてアンモニアを分解する工程と、（ｃ）工程（ｂ）からの処理ガスをＲｈ担持γ−アルミナ触媒に接触させて処理ガス中の亜酸化窒素を分解する工程とからなるものである。 The present invention basically includes (a) a step of subjecting ammonia-containing wastewater to stripping treatment to transfer ammonia into the gas phase, and (b) ammonia-containing exhaust gas from step (a), Co, Ce and A step of decomposing ammonia by contacting an oxide catalyst containing Mn and / or an oxide carrier and a catalyst containing Ag and Fe; and (c) treating the process gas from step (b) with an Rh-supported γ-alumina catalyst. And the step of decomposing nitrous oxide in the processing gas by contacting the substrate .
工程（ａ）では、アンモニア含有排水中のアンモニアをストリッピングして気相中に移行させる。このストリッピング処理は、一般に知られている方法にしたがって行うことができる。キャリヤーガスとしては、水蒸気や加熱空気などを用いることができる。
工程（ｂ）においては、環境上問題がない程度まで、ＮＯｘの副生を抑制しながら、排ガス中のアンモニアを分解する。
In the step (a), ammonia in the ammonia-containing waste water is stripped and transferred to the gas phase. This stripping process can be performed according to a generally known method. As the carrier gas, water vapor or heated air can be used.
In the step ( b ), ammonia in the exhaust gas is decomposed while suppressing by-product generation of NOx to the extent that there is no environmental problem.
なお、本発明の環境上問題がない程度の濃度とは、アンモニアは５ｐｐｍ以下、ＮＯｘは５０ｐｐｍ以下、また亜酸化窒素は５０ｐｐｍ以下を意味する。したがって、工程（ｂ）では、処理ガス中のアンモニア濃度およびＮＯｘ濃度が、それぞれ、５ｐｐｍ以下および５０ｐｐｍ以下となるようにアンモニアの酸化分解を行う。 It should be noted that the concentration of the present invention that does not cause environmental problems means that ammonia is 5 ppm or less, NOx is 50 ppm or less, and nitrous oxide is 50 ppm or less. Therefore, in the step ( b ), ammonia is oxidatively decomposed so that the ammonia concentration and the NOx concentration in the processing gas become 5 ppm or less and 50 ppm or less, respectively.
工程（ｂ）では、アンモニアを酸化分解するために、常法にしたがって、必要量の、具体的には、等量以上の酸素を空気や酸素含有ガスとして供給する。 In the step ( b ), in order to oxidatively decompose ammonia, a necessary amount, specifically, an equal amount or more of oxygen is supplied as air or an oxygen-containing gas according to a conventional method.
工程（ｂ）からの処理ガス中には亜酸化窒素が含まれているので、工程（ｂ）からの処理ガスは工程（ｃ）に導入し、ここで処理ガスを亜酸化窒素分解触媒に接触させて亜酸化窒素を環境上問題がない程度まで分解する。 Since the process gas from step ( b ) contains nitrous oxide, the process gas from step ( b ) is introduced into step ( c ), where the process gas contacts the nitrous oxide decomposition catalyst. To decompose nitrous oxide to an extent that there is no environmental problem.
アンモニア分解触媒におけるガス温度は、２５０〜４５０℃、好ましくは３００〜４００℃であり、空間速度（ＳＶ）は５００〜１０００００ｈｒ−１、好ましくは１０００〜５００００ｈｒ−１である。また、亜酸化窒素分解触媒におけるガス温度は３００〜６００℃、好ましくは３５０〜５５０℃であり、空間速度（ＳＶ）は５００〜１０００００ｈｒ−１、好ましくは３０００〜５００００ｈｒ−１である。
Gas temperature at the ammonia decomposition catalyst, 250 to 450 ° C., preferably from 300 to 400 ° C., a space velocity (SV) is 500~100000hr -1, preferably 1000~50000hr -1. The gas temperature is 300 to 600 ° C. in the nitrous oxide decomposition catalyst, preferably 350 to 550 ° C., a space velocity (SV) is 500～100000Hr -1, preferably 3000~50000hr -1.
アンモニア分解触媒および亜酸化窒素分解触媒はそれぞれ異なる２つの反応管に充填しても、あるいは一つの反応管にアンモニア分解触媒および亜酸化窒素分解触媒を２段に分けて充填してもよい。 The ammonia decomposition catalyst and the nitrous oxide decomposition catalyst may be charged in two different reaction tubes, or the ammonia decomposition catalyst and the nitrous oxide decomposition catalyst may be charged in two stages in one reaction tube.
上記工程（ｂ）、（ｃ）を経て得られる処理ガス中に含まれるアンモニア、ＮＯｘおよび亜酸化窒素の濃度は環境上問題がない程度のものであるので、処理ガスはそのまま大気中に放出することができる。 Since the concentrations of ammonia, NOx and nitrous oxide contained in the processing gas obtained through the above steps ( b ) and ( c ) are such that there is no environmental problem, the processing gas is released into the atmosphere as it is. be able to.
本発明の「アンモニアを含有する排水」との用語は、アンモニア含有排水のほかに、アンモニアと同様にストリッピング処理により排水から気相中に移行させることができるメチルアミン、ジメチルアミン、トリメチルアミンのような含窒素化合物を含む排水も包含するものである。
The term “ammonia-containing wastewater” in the present invention refers to, in addition to ammonia-containing wastewater, methylamine, dimethylamine, and trimethylamine that can be transferred from the wastewater to the gas phase by stripping treatment in the same manner as ammonia. It also includes wastewater containing such nitrogen-containing compounds.
本発明の有利な実施態様を示している以下の実施例を挙げて、本発明を更に具体的に説明する。 The invention is further illustrated by the following examples, which illustrate advantageous embodiments of the invention.
＜アンモニア分解触媒１＞
硝酸コバルト（ＩＩ）６水和物８７３ｇ、硝酸セリウム（ＩＩ）６水和物１３０３ｇおよび硝酸マンガン（ＩＩ）６水和物１２９２ｇを純水に均一に溶解した。この水溶液を加熱することで水分を蒸発させＣｏ、Ｃｅ、Ｍｎを含む混合粉体を得た。次いで、この混合粉体を５５０℃にて５時間焼成してＣｏ、Ｃｅ、Ｍｎからなる酸化物粉体を調製した。この酸化物粉体８００ｇにγ−アルミナ粉体４００ｇを添加、混合して球状（平均粒子径５ｍｍ）に成形した後、１２０℃にて５時間乾燥し、次いで５５０℃で３時間焼成してＣｏ−Ｃｅ−Ｍｎ系アンモニア分解触媒を得た。この触媒組成は、Ｃｏ３Ｏ４：ＣｅＯ２：ＭｎＯ２：Ａｌ２Ｏ３＝１：２．１：１．６：２．４（質量比）であった。
＜アンモニア分解触媒２＞
チタン酸化物粉体（ミレニアム社製、商品名ＤＴ−５１）を球状（平均粒径５ｍｍ）に成形した後、１２０℃にて５時間乾燥し、次いで５００℃にて３時間焼成した。この球状チタン酸化物を硝酸銀水溶液に含浸した。含浸後、１２０℃にて５時間乾燥し、次いで５００℃にて３時間焼成した。次いで、硫酸第一鉄水溶液に含浸し、１２０℃にて５時間乾燥し、次いで５００℃にて３時間焼成してアンモニア分解触媒２を得た。この触媒の組成は、ＴｉＯ２：Ａｇ：Ｆｅ＝８０：１７：３（質量比）であった。
＜亜酸化窒素分解触媒＞
所定の濃度に調整した硝酸ロジウム水溶液にγ−アルミナペレット（住友化学工業（株）製、平均粒子径５ｍｍ）を５分間浸漬し、その後、１２０℃にて５時間乾燥した後、６００℃で５時間焼成してＲｈ担持γ−Ａｌ２Ｏ３触媒を調製した。この触媒組成は、Ｒｈ：Ａｌ２Ｏ３＝５：９５（質量比）であった。
実施例１
内径４５ｍｍ、長さ９５０ｍｍのステンレス鋼製反応管のガス入口側に上記アンモニア分解触媒１１４０ｍｌを充填し、ガス出口側に上記亜酸化窒素分解触媒１４０ｍｌを充填した。そして、アンモニア濃度４０００ｐｐｍ、水蒸気濃度 ２０％、残り空気からなる模擬アンモニア含有ガスを所定の温度（３６０℃、３８０℃および４００℃）に加熱、調整した後、供給速度１２Ｌ／ｍｉｎ（ＳＴＰ）でアンモニア分解触媒層、次いで亜酸化窒素分解触媒層に流した。各触媒層の温度が模擬アンモニア含有ガスの温度とほぼ同じになった時点で、亜酸化窒素分解触媒層からの処理ガス中のアンモニア濃度、ＮＯｘ濃度および亜酸化窒素濃度を下記の方法にしたがって測定し、またアンモニア転化率を下記の式にしたがって求めた。結果を表１に示す。
アンモニア濃度：
０．５質量％のホウ酸水溶液を含む吸収瓶に一定量のガスを通気させてガス中に含まれているアンモニアをホウ酸水溶液に吸収させ、吸収操作後のアンモニアを含むホウ酸水溶液を純水にて所定量に調節した後、日立製作所製陽イオンクロマトグラフにて液中のＮＨ４ ＋を定量することで吸収されたアンモニアを算出しガス中のアンモニア濃度を計算した。
ＮＯｘ濃度：
日本サーモエレクトロン製ＮＯｘ計 ＭＯＤＥＬ４２Ｃを用い、化学発光法により測定した。
亜酸化窒素濃度：
島津製作所製ガスクロマトグラフ（ＴＣＤ）にて測定した。
アンモニア転化率（％）：
（４０００ｐｐｍ−処理ガス中のアンモニア濃度（ｐｐｍ））／（４０００ｐｐｍ）（×１００）
実施例２
実施例１において、アンモニア分解触媒１をアンモニア分解触媒２に変更した以外は実施例１と同様にして模擬アンモニア含有ガスの処理を行った。結果を表１に示す。
比較例１
実施例１において、後段の亜酸化窒素分解触媒層を設けなかった以外は実施例１と同様にして模擬アンモニア含有ガスの処理を行った。結果を表１に示す。
<Ammonia decomposition catalyst 1>
873 g of cobalt (II) nitrate hexahydrate, 1303 g of cerium (II) nitrate hexahydrate and 1292 g of manganese (II) nitrate hexahydrate were uniformly dissolved in pure water. The aqueous solution was heated to evaporate water and obtain a mixed powder containing Co, Ce, and Mn. Next, this mixed powder was fired at 550 ° C. for 5 hours to prepare an oxide powder composed of Co, Ce, and Mn. After adding 400 g of γ-alumina powder to 800 g of this oxide powder, mixing to form a spherical shape (average particle diameter 5 mm), drying at 120 ° C. for 5 hours, and then firing at 550 ° C. for 3 hours to obtain Co A —Ce—Mn-based ammonia decomposition catalyst was obtained. The catalyst composition was Co 3 O 4 : CeO 2 : MnO 2 : Al 2 O 3 = 1: 2.1: 1.6: 2.4 (mass ratio).
<Ammonia decomposition catalyst 2>
Titanium oxide powder (trade name DT-51, manufactured by Millennium Co., Ltd.) was formed into a spherical shape (average particle size 5 mm), dried at 120 ° C. for 5 hours, and then fired at 500 ° C. for 3 hours. This spherical titanium oxide was impregnated with an aqueous silver nitrate solution. After impregnation, it was dried at 120 ° C. for 5 hours and then calcined at 500 ° C. for 3 hours. Next, it was impregnated with an aqueous ferrous sulfate solution, dried at 120 ° C. for 5 hours, and then calcined at 500 ° C. for 3 hours to obtain an ammonia decomposition catalyst 2. The composition of this catalyst was TiO 2 : Ag: Fe = 80: 17: 3 (mass ratio).
<Nitrous oxide decomposition catalyst>
Γ-alumina pellets (manufactured by Sumitomo Chemical Co., Ltd., average particle size 5 mm) are immersed in an aqueous rhodium nitrate solution adjusted to a predetermined concentration for 5 minutes, then dried at 120 ° C. for 5 hours, and then at 600 ° C. for 5 hours. Rh-supported γ-Al 2 O 3 catalyst was prepared by calcining for a period of time. The catalyst composition was Rh: Al 2 O 3 = 5: 95 (mass ratio).
Example 1
A gas inlet side of a stainless steel reaction tube having an inner diameter of 45 mm and a length of 950 mm was filled with 1140 ml of the ammonia decomposition catalyst, and the gas outlet side was filled with 140 ml of the nitrous oxide decomposition catalyst. Then, after heating and adjusting a simulated ammonia-containing gas comprising an ammonia concentration of 4000 ppm, a water vapor concentration of 20%, and the remaining air to a predetermined temperature (360 ° C., 380 ° C. and 400 ° C.), ammonia is supplied at a supply rate of 12 L / min (STP). It flowed to the cracking catalyst layer and then to the nitrous oxide cracking catalyst layer. When the temperature of each catalyst layer becomes almost the same as the temperature of the simulated ammonia-containing gas, measure the ammonia concentration, NOx concentration and nitrous oxide concentration in the treated gas from the nitrous oxide decomposition catalyst layer according to the following method The ammonia conversion rate was determined according to the following formula. The results are shown in Table 1.
Ammonia concentration:
A certain amount of gas is passed through an absorption bottle containing 0.5 mass% boric acid aqueous solution to absorb the ammonia contained in the gas into the boric acid aqueous solution, and the boric acid aqueous solution containing ammonia after the absorption operation is purified. After adjusting to a predetermined amount with water, the absorbed ammonia was calculated by quantifying NH 4 + in the liquid with a cation chromatograph manufactured by Hitachi, Ltd., and the ammonia concentration in the gas was calculated.
NOx concentration:
Measurement was performed by a chemiluminescence method using a NOx meter MODEL42C manufactured by Nippon Thermo Electron.
Nitrous oxide concentration:
It was measured with a Shimadzu gas chromatograph (TCD).
Ammonia conversion (%):
(4000 ppm-ammonia concentration in treated gas (ppm)) / (4000 ppm) (x100)
Example 2
In Example 1, the treatment of the simulated ammonia-containing gas was performed in the same manner as in Example 1 except that the ammonia decomposition catalyst 1 was changed to the ammonia decomposition catalyst 2. The results are shown in Table 1.
Comparative Example 1
In Example 1, the simulated ammonia-containing gas was treated in the same manner as in Example 1 except that the latter nitrous oxide decomposition catalyst layer was not provided. The results are shown in Table 1.
表１において、ＮＯｘおよび亜酸化窒素の濃度は、湿りガス基準の体積濃度である。 In Table 1, the concentrations of NOx and nitrous oxide are volume concentrations based on wet gas.
実施例１、２と比較例１とから、亜酸化窒素分解触媒による処理工程（工程（ｂ））を設けることにより処理ガス中の亜酸化窒素濃度を著しく低減できる。
From Examples 1 and 2 and Comparative Example 1, the concentration of nitrous oxide in the treatment gas can be significantly reduced by providing a treatment step (step (b)) using a nitrous oxide decomposition catalyst.
Claims (1)
（ａ）アンモニア含有排水をストリッピング処理に供してアンモニアを気相中に移行させる工程。
（ｂ）工程（ａ）からのアンモニア含有排ガスを、Ｃｏ、ＣｅおよびＭｎを含む酸化物触媒および／または酸化物担体とＡｇとＦｅとを含有する触媒に接触させてアンモニアを分解する工程。
（ｃ）工程（ｂ）からの処理ガスをＲｈ担持γ−アルミナ触媒に接触させて処理ガス中の亜酸化窒素を分解する工程。 A method for purifying ammonia-containing wastewater, comprising purifying wastewater containing ammonia according to a process including the following steps.
(A) step of shifting subjecting the ammonia-containing waste water in the stripped ammonia in the gas phase.
( B ) The step of decomposing ammonia by contacting the ammonia-containing exhaust gas from step ( a ) with an oxide catalyst containing Co, Ce and Mn and / or a catalyst containing an oxide carrier, Ag and Fe.
( C ) A step of bringing the processing gas from step ( b ) into contact with the Rh-supported γ-alumina catalyst to decompose nitrous oxide in the processing gas.
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| JP2006346642A (en) * | 2005-06-20 | 2006-12-28 | Sumiko Eco-Engineering Co Ltd | Catalyst for decomposing ammonia and method for treating ammonia |
| JP5127672B2 (en) * | 2008-11-06 | 2013-01-23 | 日立造船株式会社 | Ammonia decomposition catalyst |
| IT1401698B1 (en) * | 2010-09-13 | 2013-08-02 | Sued Chemie Catalysts Italia | CATALYST FOR THE DECOMPOSITION OF DANGEROUS PROSTOSIS. |
| JP5690158B2 (en) * | 2011-02-03 | 2015-03-25 | Ａｇｃセイミケミカル株式会社 | Ammonia decomposition catalyst and ammonia decomposition method |
| DK3088080T3 (en) | 2013-12-26 | 2018-06-14 | Nikki Universal Co Ltd | Ammonia Decomposition Catalyst |
| CN110918117B (en) * | 2019-11-28 | 2023-03-21 | 浙江师范大学 | Catalyst for eliminating nitrogenous organic matters and preparation method thereof |
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