JP2004033991A - Method of denitrifying combustion exhaust gas and denitrification catalyst for the same - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、燃焼排ガスの脱硝方法及び脱硝触媒に関するものである。
【０００２】
【従来の技術】
従来、尿素水を用いて、脱硝触媒の前段に加水分解触媒を設置し、該加水分解触媒によって尿素を予め加水分解し、該反応によって生成したＮＨ３により排ガス中の窒素酸化物を低減することが行なわれていた。
【０００３】
しかし、このような加水分解触媒を設置することは、機器点数の増大を招き、かつこれを別途設置できない場合もあり、対策が望まれていた。
【０００４】
【発明が解決しようとする課題】
本発明は上記事情に対してなされたもので、脱硝触媒の前段の加水分解触媒を設置することなく、窒素酸化物を含む燃焼排ガスの脱硝を行なうことができるようにした燃焼排ガスの脱硝方法及び脱硝触媒を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するため、本発明は、燃焼排ガスの脱硝方法において、脱硝触媒を用い、尿素の加水分解反応、ＨＮＣＯの加水分解反応及びＮＨ３による脱硝反応を同時に促進させるようにしたことを特徴とする。ここで、尿素の加水分解反応、ＨＮＣＯの加水分解反応及びＮＨ３による脱硝反応が、上記脱硝触媒に含まれるＶ２Ｏ５及び／又は上記脱硝触媒上の固体酸点により同時に促進されることが好適である。なお、「上記脱硝触媒に含まれるＶ２Ｏ５及び／又は上記脱硝触媒上の固体酸点により」とは、「上記脱硝触媒に含まれるＶ２Ｏ５」による場合、「上記脱硝触媒上の固体酸点」による場合、「上記脱硝触媒に含まれるＶ２Ｏ５及び上記脱硝触媒上の固体酸点」による場合のいずれかを示している。
【０００６】
本発明に係る燃焼排ガスの脱硝方法は、その実施の形態において、脱硝触媒が含有するＶ２Ｏ５の含有量を、０．５〜５．０ｗｔ．％の範囲としている。
本発明に係る燃焼排ガスの脱硝方法では、好適には、上記脱硝触媒の含有する固体酸量を０．０５ｍｍｏｌ／ｇ以上とする。
【０００７】
本発明では、その実施の形態として、上記脱硝触媒を、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種以上の担体に、Ｖ２Ｏ５及び／又はＷＯ３を担持してなる脱硝触媒としている。
また、本発明は、その実施の形態として、上記脱硝触媒が、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種以上の担体に、Ｖ２Ｏ５及び／又はＷＯ３を担持してなる脱硝触媒から成る第１の触媒層と、Ｖ２Ｏ５、ＷＯ３、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種から成る第２の触媒層とから成るものとしたものを含む。この場合、上記第２の触媒層を上層とし、上記第１の触媒層を下層とすることが好適である。
「Ｖ２Ｏ５及び／又はＷＯ３」とは、「Ｖ２Ｏ５」、「ＷＯ３」、「Ｖ２Ｏ５及びＷＯ３」のいずれかの場合をいう。
また、本発明は、別の側面において、上記燃焼排ガスの脱硝方法に用いられる脱硝触媒である。
【０００８】
【発明の実施の形態】
以下に、本発明に係る燃焼排ガスの脱硝方法をその実施の形態についてさらに詳細に説明する。
まず、本発明に係る燃焼排ガスの脱硝方法では、尿素又は尿素水（濃度 ３〜４０ｗｔ．％）を煙道中の燃焼排ガスに投入する。尿素又は尿素水を含んだ燃焼排ガスは、脱硝触媒に送る。
【０００９】
脱硝触媒では、以下のように反応が生じる。
１． 尿素の加水分解反応：
（ＮＨ２）２ＣＯ＋Ｈ２Ｏ → ＣＯ２＋２ＮＨ３
この反応で得られるアンモニアは、脱硝反応に用いられる。
２． ＨＮＣＯの加水分解反応：
ＨＮＣＯが尿素から副生する。
（ＮＨ２）２ＣＯ→ＮＨ３＋ＨＣＮＯ
このＨＣＮＯも加水分解する。
ＨＣＮＯ＋Ｈ２Ｏ → ＣＯ２＋ＮＨ３
これらのアンモニアも脱硝反応に用いられる。
３． 脱硝反応：
例えば、以下のように脱硝反応が進む。
４ＮＯ＋４ＮＨ３＋Ｏ２→４Ｎ２＋６Ｈ２Ｏ
【００１０】
本発明に係る燃焼排ガスの脱硝方法では、加水分解触媒による尿素の加水分解を行なわず、単一の脱硝触媒を用いて、上記尿素の加水分解反応、ＨＮＣＯの加水分解反応、及び脱硝反応の全てを同時に促進させるようにしている。すなわち、煙道中の燃焼排ガスに投入した尿素又は尿素水は脱硝触媒に、燃焼排ガスと共に導かれ、上記３種の反応を同時に促進し、目的とする脱硝を効率的に行なう。
【００１１】
本発明では、尿素の加水分解反応、ＨＮＣＯの加水分解反応及びＮＨ３による脱硝反応が、上記脱硝触媒に含まれるＶ２Ｏ５及び／又は上記脱硝触媒上の固体酸点により同時に促進される。
Ｖ２Ｏ５によってこのように３種の反応を促進する場合には、脱硝触媒が含有するＶ２Ｏ５の含有量を、０．５〜２．０ｗｔ．％の範囲とすることが好適であり、さらに好ましくは、０．８〜５．０ｗｔ．％の範囲とする。本発明者らは、鋭意検討した結果、このような範囲で、３種の反応が同時に促進されることを見出した。
脱硝触媒上の固体酸点により３種の反応を促進する場合には、上記脱硝触媒の含有する固体酸量を好適には、０．０５ｍｍｏｌ／ｇ以上、好ましくは、０．２ｍｍｏｌ／ｇ以上とする。本発明者らは、鋭意検討した結果、このような範囲で、３種の反応が同時に促進されることを見出した。
【００１２】
上記脱硝触媒としては、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種以上の担体に、Ｖ２Ｏ５及び／又はＷＯ３を担持してなる脱硝触媒を挙げることができる。
そして、このようなＡｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種以上の担体に、Ｖ２Ｏ５及び／又はＷＯ３を担持してなる脱硝触媒から成る第１の触媒層と、Ｖ２Ｏ５、ＷＯ３、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種から成る第２の触媒層とから成る脱硝触媒を用いることがさらに好適である。この場合、上記第２の触媒層を上層とし、上記第１の触媒層を下層とすることが好適である。このような２層型の触媒は、必ずしも完全に２層に分離しているものでなくても良く、混合部分を含む場合であっても本発明の概念に含まれる。
なお、上記ＴｉＯ２−ＳｉＯ２は、ＴｉＯ２が複合酸化物であっても良い旨の例示であり、ＴｉＯ２を含むＴｉＯ２−ＺｒＯ２、又はＴｉＯ２−Ａｌ２Ｏ３等の他種のＴｉＯ２複合酸化物を採用することも勿論できる。
これらの脱硝触媒は、いずれもＶ２Ｏ５を含有するか、少なくとも固体酸点を有する。したがって、上記尿素の加水分解反応、ＨＮＣＯの加水分解反応、及び脱硝反応の全てを同時に促進させることができる。その効果は、後に提供する実施例において確認することができる。
【００１３】
脱硝触媒の調製方法
本発明で用いられる上記脱硝触媒を調製するための調製方法として、いわゆるハニカム構造によるソリッドタイプの触媒を調製する場合について説明する。
１．まず、上記第１の触媒層をハニカム状等の多孔型形状に成型する。
このために、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種以上の担体を構成するための原料化合物の水性スラリーにＶ２Ｏ５及び／又はＷＯ３の原料化合物を加える。これらに必要に応じて成型助剤を加え、加熱ニーダ等によって水を蒸発させながら混練する。これによって、触媒ペーストを得る。
この触媒ペーストを押出成型機等によってハニカム状等の多孔型形状に成型する。
次いで、乾燥、焼成して第１の触媒層を構成するソリッド型の触媒層を得る。
【００１４】
２．上記第２の触媒層を第１の触媒層上に適用する。
第２の触媒層として、Ｖ２Ｏ５及び／又はＷＯ３を適用する場合には、一般的には、これらの原料化合物の水溶液中に上記第１の触媒層に含浸する。次いで、乾燥、焼成して脱硝触媒を得る。
第２の触媒層として、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２、ＴｉＯ２、ＴｉＯ２−ＳｉＯ２から成る群から選ばれた少なくとも１種を用いる場合には、これらのＡｌ２Ｏ３ゾル又はＳｉＯ２ゾル等を用いてスラリー状とし、該スラリーを第１の触媒上にコートする。
【００１５】
他の実施の形態
本発明に係る燃焼排ガスの脱硝方法は、上記した実施の形態に限られるものではなく、当業者にとって自明な変更・修飾・付加は、全て本発明の技術的範囲に含まれる。
例えば、上記第１の触媒層をソリッドタイプのものとして構成した。しかし、別途の支持体を設け、その上に第１層、第２層の順にコートすることもできる。
【００１６】
【実施例】
実施例１
触媒Ｎｏ．１−１）の調製
メタチタン酸スラリー（ＴｉＯ２含有量：３０ｗｔ．％）６０ｋｇに、メタバナジン酸アンモニウム１１６ｇを加え、さらに成型助剤としてデンプンを加えた後、加熱ニーダを用いて水を蒸発させながら混練し、触媒ペーストを得た。これを押出成型機にて、外形７５ｍｍ角、目開き４ｍｍ、肉厚１ｍｍ、長さ５００ｍｍのハニカム状に成型した。次に、８０℃で乾燥した後、５００℃で５時間空気雰囲気中にて焼成して触媒Ｎｏ．１−１）を得た。
【００１７】
触媒Ｎｏ．１−２）〜Ｎｏ．１−５）等の調製
上記ハニカム触媒Ｎｏ．１−１）のメタチタン酸スラリーの代わりに、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２及びＴｉＯ２−ＳｉＯ２粉末をＴｉＯ２と同重量使用し、触媒Ｎｏ．１−１）と同様の方法にて触媒ペーストを得た。これを触媒Ｎｏ．１−１）と同様に押出成型機にてハニカム形状に成型し、触媒Ｎｏ．１−２）〜Ｎｏ．１−５）を得た。
上記は、触媒Ｎｏ．１−１）〜Ｎｏ．１−５）は、いずれも、Ｖ２Ｏ５が、０．５ｗｔ．％担持されたものに相当する。適宜同様に、重量調整を行い、表１に示すように、Ｖ２Ｏ５が、０．８ｗｔ．％、１．５ｗｔ．％、２．０ｗｔ．％、５．０ｗｔ．％各々担持されるように、触媒Ｎｏ．２−１）〜Ｎｏ．５−５）を得た。
【００１８】
触媒Ｎｏ．６−１）の調製
メタチタン酸スラリー（ＴｉＯ２含有量：３０ｗｔ．％）６０ｋｇにメタバナジン酸アンモニウム１１６ｇ及びパラタングステン酸アンモニウム（（ＮＨ４）１０Ｗ１２Ｏ４１・５Ｈ２Ｏ）１．６ｋｇを加え、さらに成型助剤としてデンプンを加えた後、加熱ニーダを用いて水を蒸発させながら混練し、触媒ペーストを得た。これを押出成型機に外形７５ｍｍ角、目開き４ｍｍ、肉厚１ｍｍ、長さ５００ｍｍのハニカム状に成型した。次に、８０℃で乾燥した後、５００℃で５時間空気雰囲気中にて焼成して触媒Ｎｏ．６−１）を得た。
【００１９】
触媒Ｎｏ．６−２）〜Ｎｏ．６−５）等の調製
上記ハニカム触媒Ｎｏ．６−１）のメタチタン酸スラリーの代わりに、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２及びＴｉＯ２−ＳｉＯ２粉末をＴｉＯ２と同重量使用し、触媒Ｎｏ．６−１）と同様の方法にて触媒ペーストを得た。これを触媒Ｎｏ．６−１）と同様に押出成型機にてハニカム形状に成型し、触媒Ｎｏ．６−２）〜Ｎｏ．６−５）を得た。
上記は、触媒Ｎｏ．１−１）〜Ｎｏ．１−５）は、いずれも、Ｖ２Ｏ５が、０．５ｗｔ．％、ＷＯ３が８ｗｔ．％担持されたものに相当する。適宜同様に、重量調整を行い、表１に示すように、Ｖ２Ｏ５が、０．８ｗｔ．％、１．５ｗｔ．％、２．０ｗｔ．％、５．０ｗｔ．％各々担持され、ＷＯ３が８ｗｔ．％担持されるように、触媒Ｎｏ．６−１）〜Ｎｏ．１０−５）を得た。
【００２０】
触媒Ｎｏ．１１〜１２の調製
メタバナジン酸アンモニウム２３３ｇ、パラタングステン酸アンモニウム２．０ｋｇを各々水に溶解し、各々上記ハニカム触媒Ｎｏ．１−１）に含浸させた。次に８０℃で乾燥させた後、５００℃で５時間空気雰囲気中にて焼成して、２層型触媒Ｎｏ．１１及び１２を得た。
【００２１】
触媒Ｎｏ．１３の調製
ＴｉＯ２粉末にＡｌ２Ｏ３ゾル及びＳｉＯ２ゾルを加えて調製したＴｉＯ２スラリーを、ハニカム形状に成型した触媒Ｎｏ．１−１）に２００ｇ／ｍ２コートした。次に、８０℃で乾燥した後、５００℃で５時間空気雰囲気中にて焼成して、触媒Ｎｏ．１３を得た。
【００２２】
触媒Ｎｏ．１４〜１７の調製
上記ＴｉＯ２粉末の代わりに、Ａｌ２Ｏ３、ＳｉＯ２、ＺｒＯ２及びＴｉＯ２−ＳｉＯ２粉末を各々同重量使用し、触媒Ｎｏ．１３と同様の方法にてスラリーをコートした後、８０℃で乾燥した後、５００℃で５時間空気雰囲気中にて焼成して、表１に示す触媒Ｎｏ．１４〜１７を得た。
【００２３】
実施例２
実施例１により調製したハニカム触媒１〜１７を用いて脱硝活性評価試験を行った。評価条件を以下に示す。
＜脱硝活性評価条件＞
ＮＯ：７００ｐｐｍ、ＳＯ２：３００ｐｐｍ
Ｏ２：１０％、ＣＯ２：５％、Ｈ２Ｏ：５％、Ｎ２：バランス、ＧＨＳＶ：８，０００ｈ−１、
ガス量１１０ＮＬ／ｈ、
触媒層温度：３５０℃、脱硝触媒量：１３ｃｃ
【００２４】
なお、脱硝率は下記式にて表される。
脱硝率（％）＝（１−出口ＮＯｘ濃度／入口ＮＯｘ濃度）×１００
各ハニカム触媒を用いた場合の活性評価結果を表１及び表２に記す。なお、各触媒のピリジン吸着による固体酸量評価結果を表３及び４に示す。
【００２５】
＜ピリジン吸着による固体酸量評価条件＞
・試料重量 １２．６ｍｇ，
・前処理 ４５０℃×０．５ｈ， Ｈｅ パージ
・吸着条件 １５０℃
・脱着条件 ３０℃／ｍｉｎ．
・検出器 ＦＩＤ
【００２６】
【表１】
比較例１
（比較触媒１の調製）
メタチタン酸スラリー（ＴｉＯ２含有量：３０ｗｔ．％） ６０ｋｇ にメタバナジン酸アンモニウム２．３２ｋｇを加え、さらに成型助剤を加えた後、加熱ニーダを用いて水を蒸発させながら混練し、触媒ペーストを得た。これを押出成型機にて、外形７５ｍｍ角、目開き４ｍｍ、肉厚１ｍｍ、長さ５００ｍｍのハニカム状に成型した。次に、８０℃で乾燥した後、５００℃で５時間空気雰囲気中にて焼成して比較触媒を得た。
（比較触媒２〜３の調製）
比較触媒２〜３は、比較触媒１と同方法にて調製したものであり、Ｖ２Ｏ５が０．２ｗｔ．％、１０ｗｔ．％各々担持されるように、比較触媒２〜３を得た。
（比較触媒４の調製）
比較触媒２を調製した後、触媒Ｎｏ．１１〜１２と同方法にて、前記ハニカム型比較触媒２にＶ２Ｏ５を含浸し、Ｖ２Ｏ５が０．１ｗｔ．％担持されるように、比較触媒４を得た。
【００２８】
比較例２
比較例１により調製したハニカム状比較触媒を用いて脱硝活性評価試験を行った。評価条件は実施例２と同条件である。
比較触媒を用いた場合の脱硝活性評価結果及びピリジン吸着による固体酸量評価結果を表５に記す。
【００２９】
【表５】
以上の実施例と、比較例との対比により、本発明に係る燃焼排ガスの脱硝方法又は脱硝触媒を実施する場合、良好に脱硝を行なうことができることが了解される。
【００３１】
【発明の効果】
上記したところから明らかなように、本発明によれば、脱硝触媒の前段の加水分解触媒を設置することなく、窒素酸化物を含む燃焼排ガスの脱硝を行なうことができるようにした燃焼排ガスの脱硝方法及び脱硝触媒が提供される。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for denitration of combustion exhaust gas and a denitration catalyst.
[0002]
[Prior art]
Conventionally, using urea water, a hydrolysis catalyst is installed in front of a denitration catalyst, urea is hydrolyzed in advance by the hydrolysis catalyst, and nitrogen oxides in exhaust gas are reduced by NH 3 generated by the reaction. Was being done.
[0003]
However, installing such a hydrolysis catalyst causes an increase in the number of devices, and in some cases, it is not possible to separately install such a catalyst.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, without installing a hydrolysis catalyst in front of a denitration catalyst, a method for denitration of a combustion exhaust gas containing nitrogen oxides, and An object of the present invention is to provide a denitration catalyst.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for denitration of combustion exhaust gas, wherein a denitration catalyst is used to simultaneously promote urea hydrolysis, HNCO hydrolysis and NH 3 denitration. And Here, the hydrolysis reaction of urea, the hydrolysis reaction of HNCO, and the denitration reaction by NH 3 are simultaneously promoted by V 2 O 5 contained in the denitration catalyst and / or solid acid sites on the denitration catalyst. It is suitable. In addition, the expression “V 2 O 5 contained in the denitration catalyst and / or the solid acid point on the denitration catalyst” refers to “V 2 O 5 contained in the denitration catalyst”. If by the solid acid point "indicates either the case of" solid acid points on the V 2 O 5 and the denitration catalyst contained in the denitration catalyst ".
[0006]
In the denitration method of the combustion exhaust gas according to the present invention, in the embodiment, the content of V 2 O 5 contained in the denitration catalyst is set to 0.5 to 5.0 wt. % Range.
In the method for denitrifying flue gas according to the present invention, preferably, the amount of solid acid contained in the denitration catalyst is 0.05 mmol / g or more.
[0007]
In the present invention, as an embodiment of the present invention, the denitration catalyst is provided on at least one or more carriers selected from the group consisting of Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , and TiO 2 —SiO 2. The catalyst is a denitration catalyst supporting 2 O 5 and / or WO 3 .
The present invention provides a form of the embodiment, the denitration catalyst, the Al 2 O 3, SiO 2, ZrO 2, at least one or more carriers selected from TiO 2, TiO 2 the group consisting of -SiO 2 , V 2 O 5 and / or WO 3 , a first catalyst layer composed of a denitration catalyst, and V 2 O 5 , WO 3 , Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , TiO 2 including those as consisting of a second catalyst layer comprising at least one member selected from the group consisting of -SiO 2. In this case, it is preferable that the second catalyst layer be an upper layer and the first catalyst layer be a lower layer.
“V 2 O 5 and / or WO 3 ” means any of “V 2 O 5 ”, “WO 3 ”, “V 2 O 5 and WO 3 ”.
In another aspect, the present invention is a denitration catalyst used in the above-described method for denitration of flue gas.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the embodiment of the method for denitrifying flue gas according to the present invention will be described in more detail.
First, in the flue gas denitration method according to the present invention, urea or aqueous urea (concentration: 3 to 40 wt.%) Is introduced into the flue gas in the flue. The combustion exhaust gas containing urea or urea water is sent to a denitration catalyst.
[0009]
In the denitration catalyst, a reaction occurs as follows.
1. Urea hydrolysis reaction:
(NH 2 ) 2 CO + H 2 O → CO 2 + 2NH 3
Ammonia obtained by this reaction is used for a denitration reaction.
2. HNCO hydrolysis reaction:
HNCO is by-produced from urea.
(NH 2 ) 2 CO → NH 3 + HCNO
This HCNO also hydrolyzes.
HCNO + H 2 O → CO 2 + NH 3
These ammonias are also used for the denitration reaction.
3. Denitration reaction:
For example, the denitration reaction proceeds as follows.
4NO + 4NH 3 + O 2 → 4N 2 + 6H 2 O
[0010]
In the method for denitrifying flue gas according to the present invention, the hydrolysis of urea, the hydrolysis of HNCO, and the denitration reaction are all performed using a single denitration catalyst without hydrolyzing urea with a hydrolysis catalyst. At the same time. That is, urea or urea water introduced into the flue gas in the flue is guided to the denitration catalyst together with the flue gas, and simultaneously promotes the above three kinds of reactions to efficiently perform the intended denitration.
[0011]
In the present invention, the hydrolysis reaction of urea, the hydrolysis reaction of HNCO, and the denitration reaction by NH 3 are simultaneously promoted by V 2 O 5 contained in the denitration catalyst and / or the solid acid sites on the denitration catalyst.
If the V 2 O 5 to facilitate this way three reactions, the content of V 2 O 5 containing denitration catalyst, 0.5～2.0Wt. %, More preferably 0.8 to 5.0 wt. % Range. As a result of intensive studies, the present inventors have found that three kinds of reactions are simultaneously promoted in such a range.
When three kinds of reactions are promoted by the solid acid point on the denitration catalyst, the amount of the solid acid contained in the denitration catalyst is preferably 0.05 mmol / g or more, preferably 0.2 mmol / g or more. I do. As a result of intensive studies, the present inventors have found that three kinds of reactions are simultaneously promoted in such a range.
[0012]
As the denitration catalyst, V 2 O 5 and / or WO 3 are added to at least one or more carriers selected from the group consisting of Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , and TiO 2 —SiO 2. A supported denitration catalyst can be mentioned.
V 2 O 5 and / or WO 3 are supported on at least one or more kinds of carriers selected from the group consisting of Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , and TiO 2 —SiO 2. a first catalytic layer consisting to become denitration catalyst, V 2 O 5, WO 3 , Al 2 O 3, at least 1 SiO 2, selected from ZrO 2, TiO 2, TiO 2 the group consisting of -SiO 2 It is further preferred to use a denitration catalyst comprising a second catalyst layer comprising a seed. In this case, it is preferable that the second catalyst layer be an upper layer and the first catalyst layer be a lower layer. Such a two-layer catalyst does not necessarily have to be completely separated into two layers, and even if it includes a mixed portion, it is included in the concept of the present invention.
Incidentally, the TiO 2 -SiO 2 is illustrative of the effect that TiO 2 may be a composite oxide, TiO 2 -ZrO 2 containing TiO 2, or other species such as TiO 2 -Al 2 O 3 Of course, a TiO 2 composite oxide can be employed.
Each of these denitration catalysts contains V 2 O 5 or has at least a solid acid point. Accordingly, all of the urea hydrolysis reaction, HNCO hydrolysis reaction, and denitration reaction can be simultaneously promoted. The effect can be confirmed in the examples provided later.
[0013]
Preparation method of denitration catalyst As a preparation method for preparing the denitration catalyst used in the present invention, a case of preparing a solid type catalyst having a so-called honeycomb structure will be described.
1. First, the first catalyst layer is formed into a porous shape such as a honeycomb shape.
For this purpose, V 2 O is added to an aqueous slurry of a raw material compound for constituting at least one or more carriers selected from the group consisting of Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , and TiO 2 —SiO 2. 5 and / or the starting compound of WO 3 are added. If necessary, a molding aid is added, and the mixture is kneaded while evaporating water with a heating kneader or the like. Thereby, a catalyst paste is obtained.
This catalyst paste is formed into a porous shape such as a honeycomb shape by an extruder or the like.
Next, drying and firing are performed to obtain a solid catalyst layer that forms the first catalyst layer.
[0014]
2. The second catalyst layer is applied on the first catalyst layer.
When V 2 O 5 and / or WO 3 is applied as the second catalyst layer, generally, the first catalyst layer is impregnated with an aqueous solution of these starting compounds. Next, drying and firing are performed to obtain a denitration catalyst.
When at least one selected from the group consisting of Al 2 O 3 , SiO 2 , ZrO 2 , TiO 2 , and TiO 2 —SiO 2 is used as the second catalyst layer, these Al 2 O 3 sols or A slurry is formed using an SiO 2 sol or the like, and the slurry is coated on the first catalyst.
[0015]
Other Embodiments The method for denitrifying flue gas according to the present invention is not limited to the above-described embodiment, and all changes, modifications, and additions obvious to those skilled in the art are included in the technical scope of the present invention. .
For example, the first catalyst layer is configured as a solid type. However, it is also possible to provide a separate support and coat the first layer and the second layer in that order.
[0016]
【Example】
Example 1
Catalyst No. Preparation of 1-1) To 60 kg of metatitanic acid slurry (TiO 2 content: 30 wt.%), 116 g of ammonium metavanadate was added, and starch was further added as a molding aid, and then water was evaporated using a heating kneader. The mixture was kneaded to obtain a catalyst paste. This was molded into a honeycomb shape having an outer shape of 75 mm square, an aperture of 4 mm, a wall thickness of 1 mm, and a length of 500 mm by an extruder. Next, after drying at 80 ° C., the catalyst was fired at 500 ° C. for 5 hours in an air atmosphere to obtain a catalyst No. 1-1) was obtained.
[0017]
Catalyst No. 1-2) -No. Preparation of Honeycomb Catalyst No. 1-5) Instead of the metatitanic acid slurry of 1-1), Al 2 O 3 , SiO 2 , ZrO 2 and TiO 2 —SiO 2 powder were used in the same weight as TiO 2, and catalyst No. 1 was used. A catalyst paste was obtained in the same manner as in 1-1). This was designated as Catalyst No. As in the case of 1-1), the mixture was molded into a honeycomb shape using an extrusion molding machine. 1-2) -No. 1-5) was obtained.
The above is the catalyst No. 1-1) -No. 1-5) indicates that V 2 O 5 is 0.5 wt. % Supported. Appropriately Similarly, perform weight adjustment, as shown in Table 1, the V 2 O 5, 0.8wt. %, 1.5 wt. %, 2.0 wt. %, 5.0 wt. % Of catalyst No. 2-1) -No. 5-5) was obtained.
[0018]
Catalyst No. 6-1) Preparation of metatitanic acid slurry (TiO 2 content:. 30 wt%) ammonium metavanadate 116g and ammonium paratungstate to 60kg ((NH 4) 10 W 12 O 41 · 5H 2 O) 1.6kg was added After adding starch as a molding aid, the mixture was kneaded while evaporating water using a heating kneader to obtain a catalyst paste. This was formed into a honeycomb shape having an outer shape of 75 mm square, an aperture of 4 mm, a thickness of 1 mm, and a length of 500 mm in an extruder. Next, after drying at 80 ° C., the catalyst was fired at 500 ° C. for 5 hours in an air atmosphere to obtain a catalyst No. 6-1) was obtained.
[0019]
Catalyst No. 6-2) -No. Preparation of Honeycomb Catalyst No. 6-5) In place of the metatitanic acid slurry of 6-1), Al 2 O 3 , SiO 2 , ZrO 2 and TiO 2 —SiO 2 powder were used in the same weight as TiO 2, and catalyst No. A catalyst paste was obtained in the same manner as in 6-1). This was designated as Catalyst No. In the same manner as in 6-1), the mixture was molded into a honeycomb shape using an extrusion molding machine. 6-2) -No. 6-5) was obtained.
The above is the catalyst No. 1-1) -No. 1-5) indicates that V 2 O 5 is 0.5 wt. %, WO 3 is 8 wt. % Supported. Appropriately Similarly, perform weight adjustment, as shown in Table 1, the V 2 O 5, 0.8wt. %, 1.5 wt. %, 2.0 wt. %, 5.0 wt. % Respectively supported, WO 3 is 8 wt. % Of catalyst No. 6-1) -No. 10-5) was obtained.
[0020]
Catalyst No. Preparation of Nos. 11 to 12 233 g of ammonium metavanadate and 2.0 kg of ammonium paratungstate were each dissolved in water. 1-1) was impregnated. Next, after drying at 80 ° C., the mixture was calcined at 500 ° C. for 5 hours in an air atmosphere. 11 and 12 were obtained.
[0021]
Catalyst No. Preparation of TiO 2 powder A TiO 2 slurry prepared by adding an Al 2 O 3 sol and a SiO 2 sol to TiO 2 powder was formed into a honeycomb shape using catalyst No. 13. 1-1) was coated with 200 g / m 2 . Next, after drying at 80 ° C., it was calcined at 500 ° C. for 5 hours in an air atmosphere to obtain catalyst No. 2 13 was obtained.
[0022]
Catalyst No. Preparation of Nos. 14 to 17 Instead of the TiO 2 powder, Al 2 O 3 , SiO 2 , ZrO 2, and TiO 2 —SiO 2 powder were used in the same weight, respectively. The slurry was coated in the same manner as in the case of No. 13, dried at 80 ° C., and calcined at 500 ° C. for 5 hours in an air atmosphere. 14-17 were obtained.
[0023]
Example 2
A denitration activity evaluation test was performed using the honeycomb catalysts 1 to 17 prepared in Example 1. The evaluation conditions are shown below.
<Denitration activity evaluation conditions>
NO: 700 ppm, SO 2 : 300 ppm
O 2 : 10%, CO 2 : 5%, H 2 O: 5%, N 2 : balance, GHSV: 8,000 h −1 ,
Gas amount 110NL / h,
Catalyst layer temperature: 350 ° C, denitration catalyst amount: 13 cc
[0024]
The denitration rate is represented by the following equation.
Denitration rate (%) = (1-Outlet NOx concentration / Inlet NOx concentration) x 100
Tables 1 and 2 show the activity evaluation results when each honeycomb catalyst was used. Tables 3 and 4 show the evaluation results of the solid acid amount of each catalyst by pyridine adsorption.
[0025]
<Conditions for evaluating solid acid content by pyridine adsorption>
・ Sample weight 12.6mg,
・ Pretreatment 450 ° C × 0.5h, He purge ・ Adsorption condition 150 ° C
Desorption conditions 30 ° C / min.
・ Detector FID
[0026]
[Table 1]
Comparative Example 1
(Preparation of Comparative Catalyst 1)
After adding 2.32 kg of ammonium metavanadate to 60 kg of metatitanic acid slurry (TiO 2 content: 30 wt.%), And further adding a molding aid, the mixture was kneaded while evaporating water using a heating kneader to obtain a catalyst paste. Was. This was molded into a honeycomb shape having an outer shape of 75 mm square, an aperture of 4 mm, a wall thickness of 1 mm, and a length of 500 mm by an extruder. Next, after drying at 80 ° C., it was calcined at 500 ° C. for 5 hours in an air atmosphere to obtain a comparative catalyst.
(Preparation of Comparative Catalysts 2-3)
Comparative catalysts 2 and 3 were prepared by the same method as Comparative catalyst 1 and had a V 2 O 5 content of 0.2 wt. %, 10 wt. %, So that comparative catalysts 2 to 3 were obtained, respectively.
(Preparation of Comparative Catalyst 4)
After preparing Comparative Catalyst 2, Catalyst No. At 11-12 the same method, was impregnated with V 2 O 5 in the honeycomb Comparative Catalyst 2, V 2 O 5 is 0.1 wt. %, So that Comparative Catalyst 4 was obtained.
[0028]
Comparative Example 2
A denitration activity evaluation test was performed using the honeycomb-shaped comparative catalyst prepared in Comparative Example 1. The evaluation conditions are the same as those in the second embodiment.
Table 5 shows the evaluation results of the denitration activity when the comparative catalyst was used and the evaluation results of the solid acid amount by pyridine adsorption.
[0029]
[Table 5]
It is understood from the comparison between the above example and the comparative example that when the method for denitration of flue gas or the denitration catalyst according to the present invention is carried out, the denitration can be performed well.
[0031]
【The invention's effect】
As is apparent from the above description, according to the present invention, the denitration of the combustion exhaust gas containing nitrogen oxides can be performed without installing the hydrolysis catalyst in the preceding stage of the denitration catalyst. A method and a denitration catalyst are provided.
Claims (12)
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| JP2002198305A JP2004033991A (en) | 2002-07-08 | 2002-07-08 | Method of denitrifying combustion exhaust gas and denitrification catalyst for the same |
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| JP2006122792A (en) * | 2004-10-28 | 2006-05-18 | Hitachi Zosen Corp | Urea hydrolysis catalyst, ammonia manufacturing method, and denitration method |
| JP2006150352A (en) * | 2004-11-08 | 2006-06-15 | Nippon Shokubai Co Ltd | Catalyst and method for exhaust gas treatment |
| JP2006223937A (en) * | 2005-02-15 | 2006-08-31 | Babcock Hitachi Kk | Decomposing catalyst for urea, and exhaust gas denitrification method and apparatus using the catalyst |
| JP2009262098A (en) * | 2008-04-28 | 2009-11-12 | Ne Chemcat Corp | Exhaust gas clarifying method using selective reduction catalyst |
| EP2384807A1 (en) * | 2009-10-06 | 2011-11-09 | Mitsubishi Heavy Industries, Ltd. | Nox reduction catalyst for high-temperature exhaust gas, method for producing same, and method for reducing nox in high-temperature exhaust gas |
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- 2002-07-08 JP JP2002198305A patent/JP2004033991A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2006122792A (en) * | 2004-10-28 | 2006-05-18 | Hitachi Zosen Corp | Urea hydrolysis catalyst, ammonia manufacturing method, and denitration method |
| JP4599989B2 (en) * | 2004-10-28 | 2010-12-15 | 日立造船株式会社 | Ammonia production method and denitration method |
| JP4680748B2 (en) * | 2004-11-08 | 2011-05-11 | 株式会社日本触媒 | Exhaust gas treatment catalyst and exhaust gas treatment method |
| JP2006150352A (en) * | 2004-11-08 | 2006-06-15 | Nippon Shokubai Co Ltd | Catalyst and method for exhaust gas treatment |
| JP2006223937A (en) * | 2005-02-15 | 2006-08-31 | Babcock Hitachi Kk | Decomposing catalyst for urea, and exhaust gas denitrification method and apparatus using the catalyst |
| JP4646063B2 (en) * | 2005-02-15 | 2011-03-09 | バブコック日立株式会社 | Exhaust gas denitration method and apparatus using urea decomposition catalyst |
| JP2009262098A (en) * | 2008-04-28 | 2009-11-12 | Ne Chemcat Corp | Exhaust gas clarifying method using selective reduction catalyst |
| EP2384807A1 (en) * | 2009-10-06 | 2011-11-09 | Mitsubishi Heavy Industries, Ltd. | Nox reduction catalyst for high-temperature exhaust gas, method for producing same, and method for reducing nox in high-temperature exhaust gas |
| EP2384807A4 (en) * | 2009-10-06 | 2012-08-08 | Mitsubishi Heavy Ind Ltd | Nox reduction catalyst for high-temperature exhaust gas, method for producing same, and method for reducing nox in high-temperature exhaust gas |
| JPWO2011042953A1 (en) * | 2009-10-06 | 2013-02-28 | 三菱重工業株式会社 | Denitration catalyst for high temperature exhaust gas and method for producing the same, high temperature exhaust gas denitration method |
| US8815194B2 (en) | 2009-10-06 | 2014-08-26 | Mitsubishi Heavy Industries, Ltd. | NOx removal catalyst for high-temperature flue gas, manufacturing method thereof, and NOx removal method for high-temperature flue gas |
| US9302251B2 (en) | 2009-10-06 | 2016-04-05 | Mitsubishi Heavy Industries, Ltd. | NOx removal catalyst for high-temperature flue gas, manufacturing method thereof, and NOx removal method for high-temperature flue gas |
| JP2013078768A (en) * | 2013-02-04 | 2013-05-02 | Mitsubishi Heavy Ind Ltd | Denitration catalyst for high-temperature exhaust gas, method for producing the catalyst, and method for denitrating high-temperature exhaust gas |
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