JP4798909B2

JP4798909B2 - Nitrogen oxide removing catalyst and method for producing the same

Info

Publication number: JP4798909B2
Application number: JP2001296580A
Authority: JP
Inventors: 孝男平川; 浩司増田; 雅昭内田; 一博西井
Original assignee: Catalysts and Chemicals Industries Co Ltd
Current assignee: JGC Catalysts and Chemicals Ltd
Priority date: 2001-09-27
Filing date: 2001-09-27
Publication date: 2011-10-19
Anticipated expiration: 2021-09-27
Also published as: JP2003093880A

Description

【０００１】
【発明の属する技術分野】
本発明は、窒素酸化物除去用触媒およびその製造方法に関し、更に詳しくは、重油や石炭焚きボイラ、火力発電所、製鉄所などをはじめ各種工場の燃焼炉などから排出される排ガス中に含有される窒素酸化物（以下、ＮＯ_Ｘと略記する）の除去用触媒およびその製造方法に関するものである。
【０００２】
【従来技術】
排ガス中のＮＯ_Ｘを、アンモニアなどの還元剤を使用して除去する脱硝触媒としては、一般に酸化チタン担体に酸化タングステン、酸化バナジウムなどの活性成分を担持した、ハニカム形状の触媒が工業的に使用されている。工業的に使用される脱硝触媒は、排ガス中に含まれるダスト、硫黄化合物（以下、ＳＯ_Ｘと略記する）などにも対処することが必要であるため、ただ単に脱硝活性が高いだけでなく、ＳＯ_３への酸化能（ＳＯ_３転化率）が低いこと等の種々の性能が要求される。
【０００３】
一般に、排ガス中に含まれるＳＯ_Ｘの大部分はＳＯ_２であるが、このＳＯ_２の一部は脱硝触媒上で酸化されてＳＯ_３となり、このＳＯ_３は還元剤として使用するＮＨ_３の未反応分と結合して酸性硫安を生成し、後流の熱交換器などの装置の閉塞を起こすため、またＳＯ_３そのものが装置などの腐蝕を起こすなどの問題があった。そこでＳＯ_３への転化率の低い脱硝触媒が望まれていた。
【０００４】
前述のＳＯ_３への転化率を抑制した触媒に関して、特公平４−１７０９１号公報には、予めチタンとタングステン及びケイ素の三元系酸化物を形成せしめた後該酸化物にバナジウム化合物を添加することを特徴とする脱硝触媒の調製方法が提案されている。
【０００５】
また、特許第２８２５３４３号公報には、窒素酸化物をアンモニアと共に接触的に反応せしめて選択還元する触媒を製造する方法において、可溶性チタン化合物と可溶性ケイ素化合物および／またはシリカゾルとを出発原料として用い、水性媒体中で該原料をアンモニアによって中和せしめて共沈物を得、該共沈物スラリーをｐＨが８．５以上の範囲で２０時間以上熟成せしめた後、これを洗浄し、乾燥し、次いで焼成して得られるチタンおよびケイ素からなる二元系複合酸化物を触媒（イ）成分とし、バナジウム酸化物を触媒（ロ）成分とし、タングステン酸化物を触媒（ハ）成分として用いてなり、その組成がそれぞれ（イ）成分は８２〜９７重量％、（ロ）成分は０．３〜３重量％および（ハ）成分は３〜１５重量％の範囲、さらに（イ）成分の組成が原子百分率でチタン７０〜９０％、ケイ素３０〜１０％の範囲に調整されてなることを特徴とする窒素酸化物除去用触媒の製造方法が提案されている。
しかし、該発明の製造方法では、ハニカム形状など複雑な形状の触媒に成形する場合には、二元系複合酸化物が単純な粒度分布であるため、可塑性が低く、粒子間結合力が弱く、成形性が悪いという問題があった。また、成形性を向上させ、成形体強度を向上させるために大量の成形助剤や粘土を使用する必要があり、そのため、触媒性能が低下する問題もあった。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、ＮＯ_Ｘ、特にＮＯ_ＸおよびＳＯ_Ｘを同時に含有する排ガスにアンモニアを加え、接触的に反応させるに際して、従来より提案されている窒素酸化物除去用触媒よりも更にＮＯ_Ｘ除去率が高くて、しかもＳＯ_３への転化率が低く、耐久性に優れた工業触媒として有用な窒素酸化物除去用触媒およびハニカム形状など複雑な形状の触媒でも成形性が良好な該触媒の製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の第１は、可溶性チタン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくは、可溶性チタン化合物、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に、塩基性水溶液を添加・中和して得られる複合水酸化物（ｘ成分）スラリーと、メタチタン酸スラリーと可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくはメタチタン酸スラリー、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に塩基性水溶液を添加・中和して得られる複合水酸化物（ｙ成分）スラリーとを用い、得られた複合酸化物（Ａ成分）ならびにバナジウム、モリブデンおよびタングステンからなる群から選ばれた少なくとも一種の金属の酸化物（Ｂ成分）を含有する窒素酸化物除去用触媒に関する。
【０００８】
該窒素酸化物除去用触媒では、前記複合酸化物（Ａ成分）中に含まれるｘ成分由来の複合酸化物の量が５〜３０重量％の範囲にあることが好ましい。
【０００９】
また、前記複合酸化物（Ａ成分）の組成が、酸化チタンとして７５〜９０重量％、酸化ケイ素として１０〜２０重量％、酸化タングステンとして０〜５重量％の範囲にあることが好ましい。
【００１０】
前記複合酸化物（Ａ成分）が酸化物基準で硫酸根をＳＯ_４として１〜１０重量％含有することが好ましい。
【００１１】
さらに、前記複合酸化物（Ａ成分）を８５〜９９．９重量％、金属酸化物（Ｂ成分）を０．１〜１５重量％の割合で含有することが好ましい。
【００１２】
本発明の第２は、（１）可溶性チタン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくは可溶性チタン化合物、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に、塩基性水溶液を添加・中和して複合水酸化物（ｘ成分）のスラリーを得、（２）別途、メタチタン酸スラリーと可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくはメタチタン酸スラリー、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に、塩基性水溶液を添加・中和して複合水酸化物（ｙ成分）スラリーを得、（３）前述のｘ成分である複合水酸化物のスラリーとｙ成分である複合水酸化物のスラリーとを混合した後、洗浄、乾燥して得られた複合水酸化物（ａ成分）または複合酸化物（Ａ成分）に、バナジウム、モリブデンおよびタングステンからなる群から選ばれた少なくとも一種の金属の酸化物の前駆物質（ｂ成分）を担持し、乾燥、焼成することを特徴とする窒素酸化物除去用触媒の製造方法に関する。
【００１３】
【発明の実施の形態】
以下、本発明の好適な実施形態について、詳細に説明する。
【００１４】
本発明の窒素酸化物除去用触媒では、可溶性チタン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくは可溶性チタン化合物、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に塩基性水溶液を添加・中和して得られた複合水酸化物（ｘ成分）スラリーを使用する。該複合水酸化物（ｘ成分）は、別の複合水酸化物（ｙ成分）との混合状態で熱履歴を受けて複合酸化物（Ａ成分）に転化する前駆物質である。該複合酸化物（Ａ成分）は、酸化チタンおよび酸化ケイ素、または酸化チタン、酸化タングステンおよび酸化ケイ素の単なる混合物ではなく、いわゆる二元系複合酸化物（ＴｉＯ_２−ＳｉＯ_２）または三元系複合酸化物（ＴｉＯ_２−ＷＯ_３−ＳｉＯ_２）を形成する。
【００１５】
本発明でのメタチタン酸スラリーと可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくはメタチタン酸スラリー、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に塩基性水溶液を添加・中和して得られる複合水酸化物（ｙ成分）スラリーは、前記の複合水酸化物（ｘ成分）との混合状態で熱履歴を受けて複合酸化物（Ａ成分）に転化する前駆物質である。該複合酸化物（Ａ成分）が、酸化チタンおよび酸化ケイ素、または酸化チタン、酸化タングステンおよび酸化ケイ素の単なる混合物ではなく、いわゆる二元系複合酸化物（ＴｉＯ_２−ＳｉＯ_２）または三元系複合酸化物（ＴｉＯ_２−ＷＯ_３−ＳｉＯ_２）を形成することは前記と同じである。
【００１６】
本発明でのＡ成分である複合酸化物は、前述のｘ成分である複合水酸化物のスラリーとｙ成分である複合水酸化物のスラリーとの混合物を熱処理して得られた触媒成分であるため、得られる触媒は、脱窒素活性が高くて、しかもＳＯ_２酸化活性が低く、耐久性に優れている。
【００１７】
本発明の窒素酸化物除去用触媒では、前記複合酸化物（Ａ成分）中に含まれるｘ成分由来の複合酸化物の量（ｘ／Ａ）が５〜３０重量％の範囲にあることが好ましい。ｘ／Ａの値が５重量％よりも小さい場合は、脱窒素活性は高くなるがＳＯ_２酸化活性も高くなる傾向にあり、また、ｘ／Ａの値が３０重量％よりも大きい場合は、触媒の成形性が悪くなる傾向にあり、また、ＳＯ_２酸化活性は低くなるが脱窒素活性も低くなる傾向にある。好ましいｘ／Ａの範囲は１０〜２０重量％である。
【００１８】
また、前記複合酸化物（Ａ成分）の組成は、酸化チタンとして７５〜９０重量％、酸化ケイ素として１０〜２０重量％、酸化タングステンとして０〜５重量％の範囲にあることが好ましい。酸化ケイ素の量が１０重量％より少ない場合には低いＳＯ_２酸化活性が得られないことがあり、また、２０重量％より多い場合には脱窒素活性が低くなり、また、成型性が悪くなることがある。また、酸化タングステンの量が５重量％より多くなると、タングステンは複合水酸化物を形成しない状態で存在することがあるので効果的でない。
【００１９】
また、前記複合酸化物（Ａ成分）は、酸化物基準で硫酸根をＳＯ_４として１〜１０重量％含有することが好ましい。Ａ成分中に硫酸根を含有させることにより脱硝活性が高くなる傾向を示し、１重量％より少ない場合にはその効果が少なく、１０重量％より多く含有させてもその効果は変わらない。好ましい硫酸根の量は２〜８重量％の範囲である。
【００２０】
本発明の窒素酸化物除去用触媒では、バナジウム、モリブデンおよびタングステンからなる群から選ばれた少なくとも一種の金属の酸化物（Ｂ成分）を含有するが、その他の金属酸化物を含有していてもよい。特に、酸化バナジウムおよび酸化タングステンは好適な金属酸化物である。
本発明の窒素酸化物除去用触媒は、前記複合酸化物（Ａ成分）を８５〜９９．９重量％、前記金属酸化物（Ｂ成分）を０．１〜１５重量％の割合で含有することが好ましい。Ｂ成分の割合が０．１重量％より少ない場合には、所望の脱窒素活性が得られないことがあり、また、１５重量％より多い場合にはＳＯ_２酸化活性が高くなることがある。好ましくは、Ａ成分が９０〜９９．５重量％、Ｂ成分が０．５〜１０重量％の範囲割合である。
【００２１】
次に、本発明の窒素酸化物除去用触媒の製造方法について述べる。
本発明の方法で使用される可溶性チタン化合物としては、塩化チタン、硫酸チタンなどの無機チタン化合物およびシュウ酸チタン、テトライソプロピルチタネートなどの有機チタン化合物が例示され、またケイ素源としては、シリカゾルのほか、可溶性ケイ素化合物として、四塩化ケイ素など無機ケイ素化合物およびエチルシリケイト、メチルシリケイトなどの有機ケイ素化合物が例示される。可溶性タングステン化合物としては、パラタングステン酸アンモン、メタタングステン酸アンモンなどが例示される。
【００２２】
本発明の方法では、前述の可溶性チタン化合物と前述の可溶性ケイ素化合物および／またはシリカゾルとの混合水溶液、もしくは前述の可溶性チタン化合物と前述の可溶性タングステン化合物と前述の可溶性ケイ素化合物および／またはシリカゾルとの混合水溶液に塩基性水溶液を添加・中和して複合水酸化物（ｘ成分）スラリーを調製するが、中和はｐＨ９〜１０．５の範囲で行うのが望ましく、さらに、ｐＨ９〜１０．５の範囲で熟成することがとくに望ましい。本発明で使用される塩基性水溶液としては、アンモニア水、尿素水溶液、アミン水溶液など周知の塩基性水溶液が使用可能であるが、特にアンモニア水は好適である。
【００２３】
本発明の方法では、前述のｘ成分である複合水酸化物のスラリーとは別に、メタチタン酸スラリーと可溶性ケイ素化合物および／またはシリカゾルの混合水溶液、もしくはメタチタン酸スラリー、可溶性タングステン化合物、可溶性ケイ素化合物および／またはシリカゾルの混合水溶液に塩基性水溶液を添加・中和して複合水酸化物（ｙ成分）スラリーを調製するが、中和はｐＨ９〜１０．５の範囲で行うのが望ましく、さらに、ｐＨ９〜１０．５の範囲で熟成することがとくに望ましい。この場合にも前述の塩基性水溶液が使用可能である。
【００２４】
前述のｘ成分である複合水酸化物のスラリーとｙ成分である複合水酸化物のスラリーとを混合した後、洗浄、乾燥して得られた複合水酸化物（ａ成分）または複合酸化物（Ａ成分）に、バナジウム、モリブデンおよびタングステンからなる群から選ばれた少なくとも一種の金属の酸化物の前駆物質（ｂ成分）および粘土、可塑剤などを添加して混練捏和し、所望の形状に成型し、乾燥、３００〜８００℃で焼成することが好ましい。
【００２５】
ｂ成分である前駆物質には、バナジウム源としてはメタバナジン酸アンモン、硫酸バナジル、シュウ酸バナジル、五酸化バナジウムなど、モリブデン源としてはパラモリブデン酸アンモン、三酸化モリブデンなど、タングステン源としてはパラタングステン酸アンモン、酸化タングステンなどが例示される。
また、ｂ成分の担持は、周知の担持方法が採用でき、例えば、前述の複合水酸化物（ａ成分）を所望の形状に成型し、乾燥、焼成して得た複合酸化物（Ａ成分）に、Ｂ成分の前駆物質（ｂ成分）あるいはＢ成分を含浸して調製することもできる。
【００２６】
本発明の製造方法の概略を下記フローシートに示す。
【表１】

【００２７】
本発明の窒素酸化物除去用触媒は、ＮＯ_Ｘを含有する排ガス、特にボイラ排ガスなどのようにＮＯ_Ｘ、ＳＯ_Ｘを含有するほか、重金属、ダストを含有する排ガスに、アンモニアなどの還元剤を添加して接触還元するＮＯ_Ｘ除去法に好適に使用される。また該触媒の使用条件は、通常の脱硝処理条件が採用され、具体的には、反応温度１５０〜６００℃、空間速度１，０００〜１００，０００ｈｒ^−１の範囲などが例示される。
【００２８】
【実施例】
以下に実施例を示し本発明を具体的に説明するが、本発明はこれらにより何ら限定されるものではない。
【００２９】
実施例１
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）製〕４．２２ｋｇを取り、水１６．８８ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕０．７５ｋｇを１５分間かけて添加混合し、これに、温度６０℃以下を維持しながら３規定アンモニア水９．１１ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し、温度６０℃で１時間加温熟成した。
別途、メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）製〕４０．５ｋｇに、シリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕６．７５ｋｇを１０分間かけて添加混合した後、３規定アンモニア水２．４３ｋｇを添加・中和し、更にｐＨ９．５〜１０を維持し、温度６０℃で５時間加温熟成してｙ成分である複合水酸化物のスラリーを調製した。
このｙ成分である複合水酸化物のスラリーに前述のｘ成分である複合水酸化物のスラリーを混合、攪拌した後、この混合物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２からなる２元系複合酸化物（Ａ成分）を得た。なお、該２元系複合酸化物中のＳＯ_４含有量は４．７重量％であった。
次に、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の二元系複合酸化物（Ａ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性は良好であった。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒Ｉを調製した。
【００３０】
実施例２
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）製〕１２．７ｋｇを取り、水５０．８ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成（株）製〕２．２５ｋｇを１５分間かけて添加混合し、これに、温度６０℃以下を維持しながら３規定アンモニア水２７．３４ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し温度６０℃で１時間加温熟成した。
別途、メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）製〕３１．５ｋｇに、シリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕５．２５ｋｇを１０分間かけて添加混合した後、３規定アンモニア水１．８９ｋｇを添加・中和し、更にｐＨ９．５〜１０を維持し、温度６０℃で５時間加温熟成してｙ成分に相当する複合水酸化物のスラリーを調製した。
このｙ成分である複合水酸化物のスラリーに前述のｘ成分である複合水酸化物のスラリーを混合攪拌した後、この混合物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２からなる二元系複合酸化物（Ａ成分）を得た。なお、該２元系複合酸化物中のＳＯ_４含有量は４．９重量％であった。
次に、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の二元系複合酸化物（Ａ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性は良好であった。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒IIを調製した。
【００３１】
実施例３
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）製〕１．８８ｋｇを取り、水７．５２ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕０．７５ｋｇを１５分間かけて添加混合し、これに、温度６０℃以下を維持しながら３規定アンモニア水４．０５ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し、温度６０℃で１時間加温熟成した。
別途、メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）〕３８．０ｋｇに、シリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕１４．２ｋｇを１０分間かけて添加混合した後、３規定アンモニア水２．２８ｋｇを添加・中和し、更にｐＨ９．５〜１０を維持し、温度６０℃で５時間加温熟成してｙ成分である複合水酸化物のスラリーを調製した。
このｙ成分に相当する複合水酸化物のスラリーに前述のｘ成分である複合水酸化物のスラリーを混合攪拌した後、この混合物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２からなる二元系複合酸化物（Ａ成分）を得た。なお、該２元系複合酸化物中のＳＯ_４含有量は４．９重量％であった。
次に、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の二元系複合酸化物（Ａ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性は良好であった。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒IIIを調製した。
【００３２】
実施例４
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）製〕７．５ｋｇをとり、水３０．０ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）〕３．０ｋｇを１５分間かけて添加混合し、これに、温度６０℃以下を維持しながら３規定アンモニア水１６．２ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し、温度６０℃で１時間加温熟成した。
別途、メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）製〕３２．０ｋｇに、シリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕１２．０ｋｇを１０分間かけて添加混合した後、３規定アンモニア水１．９２ｋｇを添加・中和し、更にｐＨ９．５〜１０を維持し、温度６０℃で５時間加温熟成してｙ成分である複合水酸化物のスラリーを調製した。
このｙ成分である複合水酸化物のスラリーに前述のｘ成分である複合水酸化物のスラリーを混合、攪拌した後、この混合物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２からなる二元系複合酸化物（Ａ成分）を得た。該２元系複合酸化物中のＳＯ_４含有量は４．９重量％であった。
次に、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の二元系複合酸化物（Ａ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性は良好であった。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒IVを調製した。
【００３３】
実施例５
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）製〕７．５ｋｇをとり、水３０．０ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕２．１ｋｇを１５分間かけて添加混合し、更に、０．１７ｋｇパラタングステン酸アンモニウム結晶を添加し、これに、温度６０℃以下を維持しながら３規定アンモニア水１６．２ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２−ＷＯ_３複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し、温度６０℃で１時間加温熟成した。
別途、メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）製〕３２．０ｋｇに、シリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）〕１２．０ｋｇを１０分間かけて添加混合した後、３規定アンモニア水１．９２ｋｇを添加・中和し、更にｐＨ９．５〜１０を維持し、温度６０℃で５時間加温熟成してｙ成分である複合水酸化物のスラリーを調製した。
このｙ成分である複合水酸化物のスラリーに前述のｘ成分である複合水酸化物のスラリーを混合攪拌した後、この混合物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２−ＷＯ_３からなる三元系複合酸化物（Ａ成分）を得た。該２元系複合酸化物中のＳＯ_４含有量は４．９重量％であった。
次いで、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の三元系複合酸化物（Ａ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性は良好であった。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒Ｖを調製した。
【００３４】
実施例６
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）〕７．５ｋｇをとり、水３０．０ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製）〕３．０ｋｇを１５分間かけて添加混合し、温度６０℃以下を維持しながら３規定アンモニア水１６．２ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し、温度６０℃で１時間加温熟成した。
別途、メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）製〕３２．０ｋｇに、シリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕１１．２５ｋｇを１０分間かけて添加混合し、更に、パラタングステン酸アンモニウム結晶０．１７ｋｇを添加した後、３規定アンモニア水１．９２ｋｇを添加・中和し、更にｐＨ９．５〜１０を維持し、温度６０℃で５時間加温熟成してｙ成分である複合水酸化物のスラリーを調製した。
このｙ成分である複合水酸化物のスラリーに前述のｘ成分である複合水酸化物のスラリーを混合攪拌した後、この混合物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２−ＷＯ_３からなる三元系複合酸化物（Ａ成分）を得た。該２元系複合酸化物中のＳＯ_４含有量は４．９重量％であった。
次いで、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の三元系複合酸化物（Ａ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性は良好であった。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒VIを調製した。
【００３５】
比較例１
チタン源として硫酸チタニル結晶〔ＴｉＯ_２濃度３２重量％、テイカ（株）製〕４３．６ｋｇをとり、水１７４．４ｋｇに溶解希釈した硫酸チタニル水溶液にシリカゾル（ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製）５．２５ｋｇを１５分間かけて添加混合し、これに、温度６０℃以下を維持しながら３規定アンモニア水９４．１６ｋｇを１５分間かけて添加・中和してＴｉＯ_２−ＳｉＯ_２複合水酸化物（ｘ成分）スラリーを生成し、更にｐＨ９．５〜１０を維持し、温度６０℃で１時間加温熟成した。
この得られたＴｉＯ_２−ＳｉＯ_２複合水酸化物スラリーを脱水洗浄後、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２からなる二元系複合酸化物（ｘ成分）を得た。該２元系複合酸化物中のＳＯ_４含有量は６．９重量％であった。
次に、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の二元系複合酸化物（Ｘ成分）１２．６４ｋｇをニーダーによりて混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型したが、成形性が悪く、ハニカム状に押し出し成型するのが困難であった。しかしながら活性測定用試料分を何とか成型し、得られた成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒VIIを調製した。
【００３６】
比較例２
メタチタン酸スラリー〔ＴｉＯ_２濃度３０重量％、石原産業（株）製〕４０．０ｋｇとシリカゾル〔ＳｉＯ_２濃度２０重量％、商品名“カタロイドＳ−２０Ｌ”触媒化成工業（株）製〕１５．０ｋｇを混合した後、３規定アンモニア水１０．８ｋｇを添加して該スラリーのｐＨ９．５に調製して複合水酸化物（ｙ成分）スラリーを得た。該複合水酸化物スラリーを温度６０℃でｐＨ９．５〜１０を維持しながら１時間加温熟成後、この複合水酸化物スラリーを脱水洗浄し、４００℃以下の温度で５時間乾燥してＴｉＯ_２−ＳｉＯ_２からなる二元系複合酸化物（Ｙ成分）を得た。該２元系複合酸化物中のＳＯ_４含有量は４．２重量％であった。
次に、モノエタノールアミン０．３ｋｇと水３．０ｋｇを混合し、これにメタバナジン酸アンモニウム０．２０５ｋｇを添加、加熱溶解した。この溶解液と前述の二元系複合酸化物（Ｙ成分）１２．６４ｋｇをニーダーにより混練し、更に、粘土、ガラス繊維などの成形助剤を加えて混練捏和後、ハニカム状に押出成型した。ついで、成型物を１１０℃で乾燥した後、マッフル炉中において６００℃で焼成し触媒VIIIを調製した。
【００３７】
触媒使用例
実施例１〜６および比較例１〜３の触媒Ｉ〜VIIIについて脱硝性能を評価した。
脱硝性能試験は、各ハニカム触媒（セルピッチ７．４ｍｍ、壁厚１．０ｍｍ）から長さ３００ｍｍで３×３目に切り出したものを流通式反応器に充填し、下記条件で脱硝率を測定した。脱硝率は触媒接触前後のガス中の窒素酸化物ＮＯ_Ｘの濃度をケミルミ式窒素酸化物分析計により測定し、次式により求めたものである。
【数１】
脱硝率（容量％）＝｛〔未接触ガス中のＮＯ_Ｘ（容量ｐｐｍ）−接触ガス中のＮＯ_Ｘ（容量ｐｐｍ）〕／未接触ガス中のＮＯ_Ｘ（容量ｐｐｍ）｝×１００
＜試験条件＞

また、ＳＯ_Ｘ酸化能試験は、ハニカム触媒から３００ｍｍの長さ３×３目に切り出したものを流通式反応器に充填し、下記条件でＳＯ_３転化率を測定した。
ＳＯ_３転化率は触媒接触前後のガス中のＳＯ_２濃度を赤外線式ＳＯ_２ガス濃度測定計により測定し、次式により求めた。
【数２】
ＳＯ_３転化率（容量％）＝｛〔未接触ガス中のＳＯ_２（容量ｐｐｍ）−接触ガス中のＳＯ_２（容量ｐｐｍ）〕／未接触ガス中のＳＯ_２（容量ｐｐｍ）｝×１００
＜試験条件＞

評価結果を表２に示す。
【００３８】
【表２】

（注）Ｖ_２Ｏ_５は外割で１．０重量％とした。
【００３９】
【発明の効果】
表から明らかなように、本発明の触媒は高い脱硝率を維持しつつ極めて低いＳＯ_３転化率を示す優れた触媒であることが判る。なお、ＳＯ_３転化率が０．２０％以下の所では±０．０１％の差はかなり大きい優位差である。この様な性能を持つ触媒は硫黄成分を多く含む燃料を使用するボイラー排ガスの処理用触媒として極めて有効である。また、本発明の触媒はハニカム状に成型した場合にも成形性が良好であるため、工業触媒としての生産性も高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst for removing nitrogen oxides and a method for producing the same, and more specifically, it is contained in exhaust gas discharged from combustion furnaces of various factories such as heavy oil, coal-fired boilers, thermal power plants, and steelworks. Nitrogen oxide (hereinafter referred to as NO) _X And a method for producing the same.
[0002]
[Prior art]
NO in exhaust gas _X As a denitration catalyst that removes ammonia using a reducing agent such as ammonia, a honeycomb-shaped catalyst in which an active component such as tungsten oxide or vanadium oxide is generally supported on a titanium oxide carrier is industrially used. Industrially used denitration catalysts are dust and sulfur compounds (hereinafter referred to as SO) contained in exhaust gas. _X It is necessary not only to have high denitration activity but also SO. ₃ Oxidizing ability (SO ₃ Various performances such as low conversion are required.
[0003]
Generally, SO contained in exhaust gas _X Most of the SO ₂ But this SO ₂ Part of the catalyst is oxidized on the denitration catalyst and SO ₃ And this SO ₃ Is NH used as a reducing agent ₃ In combination with the unreacted component of the product, acid ammonium sulfate is formed, and the equipment such as the heat exchanger in the downstream is blocked. ₃ There were problems such as causing corrosion of the device itself. So SO ₃ There has been a demand for a denitration catalyst having a low conversion rate to NO.
[0004]
The aforementioned SO ₃ Japanese Patent Publication No. 4-17091 discloses a catalyst in which the conversion rate into titanium is suppressed by previously forming a ternary oxide of titanium, tungsten, and silicon, and then adding a vanadium compound to the oxide. A method for preparing a denitration catalyst has been proposed.
[0005]
Patent No. 2825343 uses a soluble titanium compound and a soluble silicon compound and / or silica sol as a starting material in a method for producing a catalyst for selective reduction by catalytically reacting nitrogen oxide with ammonia. The raw material is neutralized with ammonia in an aqueous medium to obtain a coprecipitate, and the coprecipitate slurry is aged at a pH in the range of 8.5 or more for 20 hours or more, and then washed and dried. Next, a binary composite oxide composed of titanium and silicon obtained by firing is used as a catalyst (b) component, vanadium oxide as a catalyst (b) component, and tungsten oxide as a catalyst (c) component, The composition is in the range of 82 to 97% by weight of component (a), 0.3 to 3% by weight of component (b) and 3 to 15% by weight of component (c), ) 70% to 90% titanium composition in atomic percentage of components, method for producing a nitrogen oxide removing catalyst, characterized by comprising been adjusted to a range of 30 to 10% silicon has been proposed.
However, in the production method of the present invention, when the catalyst is formed into a complex shape such as a honeycomb shape, the binary composite oxide has a simple particle size distribution, so the plasticity is low and the interparticle bonding force is weak. There was a problem of poor moldability. Moreover, in order to improve moldability and to improve the strength of the molded body, it is necessary to use a large amount of molding aids and clays, and there is also a problem that the catalyst performance is lowered.
[0006]
[Problems to be solved by the invention]
The purpose of the present invention is NO _X , Especially NO _X And SO _X When adding ammonia to the exhaust gas simultaneously containing NO and reacting it in a catalytic manner, it is more NO than the conventionally proposed catalyst for removing nitrogen oxides. _X High removal rate and SO ₃ An object of the present invention is to provide a method for producing a catalyst having good moldability even with a catalyst having a complicated shape such as a catalyst for removing nitrogen oxides and a honeycomb shape, which is useful as an industrial catalyst having a low conversion rate and excellent in durability.
[0007]
[Means for Solving the Problems]
In the first aspect of the present invention, a basic aqueous solution is added to a mixed aqueous solution of a soluble titanium compound, a soluble silicon compound and / or silica sol, or a mixed aqueous solution of a soluble titanium compound, soluble tungsten compound, soluble silicon compound and / or silica sol. Mixed hydroxide (x component) slurry obtained by neutralization, mixed aqueous solution of metatitanic acid slurry and soluble silicon compound and / or silica sol, or mixing of metatitanic acid slurry, soluble tungsten compound, soluble silicon compound and / or silica sol A composite hydroxide (y component) slurry obtained by adding / neutralizing a basic aqueous solution to an aqueous solution and selected from the group consisting of the obtained composite oxide (A component) and vanadium, molybdenum and tungsten Oxidation of at least one metal (B component) relates to a catalyst for removing nitrogen oxides containing.
[0008]
In the nitrogen oxide removing catalyst, the amount of the composite oxide derived from the x component contained in the composite oxide (component A) is preferably in the range of 5 to 30% by weight.
[0009]
The composite oxide (component A) preferably has a composition in the range of 75 to 90% by weight as titanium oxide, 10 to 20% by weight as silicon oxide, and 0 to 5% by weight as tungsten oxide.
[0010]
The composite oxide (component A) converts sulfate radicals to SO on an oxide basis. ₄ 1 to 10% by weight is preferable.
[0011]
Furthermore, it is preferable to contain the composite oxide (component A) in a proportion of 85 to 99.9 wt% and a metal oxide (component B) in a proportion of 0.1 to 15 wt%.
[0012]
The second aspect of the present invention is that (1) a basic aqueous solution is added to a mixed aqueous solution of soluble titanium compound, soluble silicon compound and / or silica sol, or a mixed aqueous solution of soluble titanium compound, soluble tungsten compound, soluble silicon compound and / or silica sol. Addition and neutralization to obtain a composite hydroxide (component x) slurry, (2) Separately, a mixed aqueous solution of metatitanic acid slurry and soluble silicon compound and / or silica sol, or metatitanic acid slurry, soluble tungsten compound, soluble silicon A mixed aqueous solution of compound and / or silica sol is added / neutralized with a basic aqueous solution to obtain a composite hydroxide (y component) slurry, and (3) the composite hydroxide slurry and y component described above as x component After mixing with the composite hydroxide slurry, the composite obtained by washing and drying. At least one metal oxide precursor (b component) selected from the group consisting of vanadium, molybdenum and tungsten is supported on a hydroxide (a component) or a composite oxide (A component), dried and fired. The present invention relates to a method for producing a catalyst for removing nitrogen oxides.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail.
[0014]
In the catalyst for removing nitrogen oxides of the present invention, a basic aqueous solution is added to a mixed aqueous solution of soluble titanium compound, soluble silicon compound and / or silica sol, or a mixed aqueous solution of soluble titanium compound, soluble tungsten compound, soluble silicon compound and / or silica sol. A composite hydroxide (component x) slurry obtained by addition and neutralization is used. The composite hydroxide (component x) is a precursor that receives a thermal history in a mixed state with another composite hydroxide (component y) and converts to a composite oxide (component A). The composite oxide (component A) is not a mere mixture of titanium oxide and silicon oxide or titanium oxide, tungsten oxide and silicon oxide, but a so-called binary composite oxide (TiO 2). ₂ -SiO ₂ ) Or ternary complex oxide (TiO) ₂ -WO ₃ -SiO ₂ ).
[0015]
It is obtained by adding and neutralizing a basic aqueous solution to the mixed aqueous solution of metatitanic acid slurry and soluble silicon compound and / or silica sol or mixed aqueous solution of metatitanic acid slurry, soluble tungsten compound, soluble silicon compound and / or silica sol in the present invention. The composite hydroxide (y component) slurry is a precursor that receives a thermal history in a mixed state with the composite hydroxide (x component) and converts to a composite oxide (component A). The composite oxide (component A) is not a mere mixture of titanium oxide and silicon oxide or titanium oxide, tungsten oxide and silicon oxide, but a so-called binary composite oxide (TiO 2). ₂ -SiO ₂ ) Or ternary complex oxide (TiO) ₂ -WO ₃ -SiO ₂ ) Is the same as described above.
[0016]
The composite oxide as component A in the present invention is a catalyst component obtained by heat-treating the mixture of the composite hydroxide slurry as x component and the composite hydroxide slurry as y component. Therefore, the resulting catalyst has a high denitrification activity and is ₂ Low oxidation activity and excellent durability.
[0017]
In the nitrogen oxide removing catalyst of the present invention, the amount (x / A) of the composite oxide derived from the x component contained in the composite oxide (component A) is preferably in the range of 5 to 30% by weight. . When the value of x / A is smaller than 5% by weight, the denitrification activity is increased, but SO ₂ Oxidation activity tends to be high, and when the value of x / A is larger than 30% by weight, the moldability of the catalyst tends to deteriorate, and SO ₂ Although the oxidation activity is low, the denitrification activity tends to be low. A preferable range of x / A is 10 to 20% by weight.
[0018]
Further, the composition of the composite oxide (component A) is preferably in the range of 75 to 90% by weight as titanium oxide, 10 to 20% by weight as silicon oxide, and 0 to 5% by weight as tungsten oxide. Low SO if the amount of silicon oxide is less than 10% by weight ₂ Oxidation activity may not be obtained, and if it is more than 20% by weight, denitrification activity may be lowered and moldability may be deteriorated. On the other hand, if the amount of tungsten oxide exceeds 5% by weight, tungsten is not effective because it may exist in a state where no composite hydroxide is formed.
[0019]
In addition, the composite oxide (component A) converts sulfate radicals into SO on an oxide basis. ₄ 1 to 10% by weight is preferable. Denitration activity tends to be increased by containing sulfate radical in component A, and the effect is small when it is less than 1% by weight, and the effect is not changed even if it is contained more than 10% by weight. A preferred amount of sulfate radical is in the range of 2-8% by weight.
[0020]
The nitrogen oxide removing catalyst of the present invention contains at least one metal oxide (component B) selected from the group consisting of vanadium, molybdenum and tungsten, but may contain other metal oxides. Good. In particular, vanadium oxide and tungsten oxide are suitable metal oxides.
The catalyst for removing nitrogen oxides of the present invention contains 85 to 99.9% by weight of the composite oxide (component A) and 0.1 to 15% by weight of the metal oxide (component B). Is preferred. If the proportion of component B is less than 0.1% by weight, the desired denitrification activity may not be obtained, and if it exceeds 15% by weight, SO ₂ Oxidation activity may increase. Preferably, the A component is in the range of 90 to 99.5% by weight and the B component is in the range of 0.5 to 10% by weight.
[0021]
Next, a method for producing the nitrogen oxide removing catalyst of the present invention will be described.
Examples of the soluble titanium compound used in the method of the present invention include inorganic titanium compounds such as titanium chloride and titanium sulfate, and organic titanium compounds such as titanium oxalate and tetraisopropyl titanate. Examples of the soluble silicon compound include inorganic silicon compounds such as silicon tetrachloride and organic silicon compounds such as ethyl silicate and methyl silicate. Examples of the soluble tungsten compound include ammonium paratungstate and ammonium metatungstate.
[0022]
In the method of the present invention, a mixed aqueous solution of the aforementioned soluble titanium compound and the aforementioned soluble silicon compound and / or silica sol, or the aforementioned soluble titanium compound, the aforementioned soluble tungsten compound, and the aforementioned soluble silicon compound and / or silica sol. A basic aqueous solution is added to the mixed aqueous solution and neutralized to prepare a composite hydroxide (component x) slurry. Neutralization is desirably performed in the range of pH 9 to 10.5, and further, pH 9 to 10.5. It is particularly desirable to age within the range. As the basic aqueous solution used in the present invention, known basic aqueous solutions such as aqueous ammonia, aqueous urea solution, and aqueous amine solution can be used, but aqueous ammonia is particularly preferable.
[0023]
In the method of the present invention, a mixed aqueous solution of metatitanic acid slurry and soluble silicon compound and / or silica sol, or metatitanic acid slurry, soluble tungsten compound, soluble silicon compound and A basic aqueous solution is added / neutralized to a mixed aqueous solution of silica sol to prepare a composite hydroxide (y component) slurry. Neutralization is preferably performed in the range of pH 9 to 10.5, and pH 9 Aging in the range of ˜10.5 is particularly desirable. Also in this case, the aforementioned basic aqueous solution can be used.
[0024]
A composite hydroxide (a component) or a composite oxide obtained by mixing the slurry of the composite hydroxide that is the x component and the slurry of the composite hydroxide that is the y component, followed by washing and drying ( A component) is added to at least one metal oxide precursor selected from the group consisting of vanadium, molybdenum and tungsten (component b) and clay, plasticizer, etc., kneaded and kneaded to obtain a desired shape. It is preferable to mold, dry, and fire at 300 to 800 ° C.
[0025]
The precursors as component b include ammonium metavanadate, vanadyl sulfate, vanadyl oxalate, and vanadium pentoxide as vanadium sources, ammonium paramolybdate and molybdenum trioxide as molybdenum sources, and paratungstic acid as tungsten sources. Examples include ammon and tungsten oxide.
The component b can be supported by a well-known supporting method. For example, the composite oxide (component A) obtained by molding the composite hydroxide (component a) into a desired shape, drying, and firing. Further, it can be prepared by impregnating the precursor of the B component (b component) or the B component.
[0026]
The outline of the production method of the present invention is shown in the following flow sheet.
[Table 1]

[0027]
The catalyst for removing nitrogen oxides of the present invention is NO. _X NO, such as exhaust gas containing NO, especially boiler exhaust gas _X , SO _X In addition to NO, NOx is reduced by catalytic reduction by adding a reducing agent such as ammonia to exhaust gas containing heavy metals and dust. _X It is suitably used for the removal method. The catalyst is used under normal denitration conditions. Specifically, the reaction temperature is 150 to 600 ° C., the space velocity is 1,000 to 100,000 hours. ^-1 This range is exemplified.
[0028]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[0029]
Example 1
Titanium sulfate crystals [TiO as titanium source ₂ Silica sol [SiO2] was added to an aqueous solution of titanyl sulfate dissolved in 16.88 kg of water. ₂ Concentration 20% by weight, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 0.75 kg was added and mixed for 15 minutes, and 3N ammonia water 9. Add and neutralize 11kg over 15 minutes to TiO ₂ -SiO ₂ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5 to 10 and aged by heating at 60 ° C. for 1 hour.
Separately, metatitanic acid slurry [TiO ₂ Concentration of 30% by weight, manufactured by Ishihara Sangyo Co., Ltd.] ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 6.75 kg was added and mixed over 10 minutes, 2.43 kg of 3N ammonia water was added and neutralized, and pH 9 The slurry of composite hydroxide which is y component was prepared by heating and aging at a temperature of 60 ° C. for 5 hours.
The composite hydroxide slurry, which is the x component, is mixed and stirred with the composite hydroxide slurry, which is the y component, and then the mixture slurry is dehydrated and washed and dried at a temperature of 400 ° C. or less for 5 hours. TiO ₂ -SiO ₂ A binary composite oxide (component A) was obtained. The SO in the binary complex oxide ₄ The content was 4.7% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added thereto and dissolved by heating. This solution and 12.64 kg of the binary composite oxide (component A) described above were kneaded by a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. However, the moldability was good. Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare Catalyst I.
[0030]
Example 2
Titanium sulfate crystals [TiO as titanium source ₂ Silica sol [SiO2] was dissolved in an aqueous solution of titanyl sulfate dissolved in 50.8 kg of water. ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalytic Chemicals Co., Ltd.] 2.25 kg was added and mixed over 15 minutes, and 3N ammonia water 27.34 kg while maintaining the temperature below 60 ° C. Is added and neutralized over 15 minutes to obtain TiO ₂ -SiO ₂ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5-10 and aged by heating at a temperature of 60 ° C. for 1 hour.
Separately, metatitanic acid slurry [TiO ₂ Concentration 30% by weight, manufactured by Ishihara Sangyo Co., Ltd.] 31.5 kg, silica sol [SiO ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 5.25 kg was added and mixed over 10 minutes, then 1.89 kg of 3 N ammonia water was added and neutralized, and pH 9 The composite hydroxide slurry corresponding to the y component was prepared by heating and aging at a temperature of 60 ° C. for 5 hours.
The composite hydroxide slurry as the x component is mixed and stirred in the composite hydroxide slurry as the y component, and the mixture slurry is dehydrated and washed, and dried at a temperature of 400 ° C. or less for 5 hours. ₂ -SiO ₂ A binary composite oxide (component A) was obtained. The SO in the binary complex oxide ₄ The content was 4.9% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added thereto and dissolved by heating. This solution and 12.64 kg of the binary composite oxide (component A) described above were kneaded by a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. However, the moldability was good. Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare Catalyst II.
[0031]
Example 3
Titanium sulfate crystals [TiO as titanium source ₂ Silica sol [SiO2] was dissolved in an aqueous solution of titanyl sulfate dissolved in 7.52 kg of water. ₂ Concentration 20% by weight, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 0.75 kg was added and mixed over 15 minutes. Add and neutralize 05kg over 15 minutes to TiO ₂ -SiO ₂ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5 to 10 and aged by heating at 60 ° C. for 1 hour.
Separately, metatitanic acid slurry [TiO ₂ Concentration 30% by weight, Ishihara Sangyo Co., Ltd.] 38.0 kg, silica sol [SiO ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 14.2 kg was added and mixed for 10 minutes, then 2.28 kg of 3N ammonia water was added and neutralized, and pH 9 The slurry of composite hydroxide which is y component was prepared by heating and aging at a temperature of 60 ° C. for 5 hours.
The composite hydroxide slurry corresponding to the y component is mixed and stirred in the composite hydroxide slurry corresponding to the y component, and the mixture slurry is dewatered and washed at a temperature of 400 ° C. or lower for 5 hours. TiO ₂ -SiO ₂ A binary composite oxide (component A) was obtained. The SO in the binary complex oxide ₄ The content was 4.9% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added thereto and dissolved by heating. This solution and 12.64 kg of the binary composite oxide (component A) described above were kneaded by a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. However, the moldability was good. Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare Catalyst III.
[0032]
Example 4
Titanium sulfate crystals [TiO as titanium source ₂ The silica sol [SiO2] was dissolved in an aqueous solution of titanyl sulfate dissolved in 30.0 kg of water. ₂ Concentration 20% by weight, trade name “Cataloid S-20L” Catalytic Chemical Industry Co., Ltd.] 3.0 kg was added and mixed over 15 minutes, and 3N ammonia water 16.2 kg while maintaining the temperature at 60 ° C. or lower. Is added and neutralized over 15 minutes to obtain TiO ₂ -SiO ₂ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5 to 10 and aged by heating at 60 ° C. for 1 hour.
Separately, metatitanic acid slurry [TiO ₂ Concentration 30% by weight, made by Ishihara Sangyo Co., Ltd.] 32.0 kg, silica sol [SiO ₂ Concentration 20% by weight, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] After 12.0 kg was added and mixed for 10 minutes, 1.92 kg of 3N ammonia water was added and neutralized, and pH 9 The slurry of composite hydroxide which is y component was prepared by heating and aging at a temperature of 60 ° C. for 5 hours.
The composite hydroxide slurry, which is the x component, is mixed and stirred with the composite hydroxide slurry, which is the y component, and then the mixture slurry is dehydrated and washed and dried at a temperature of 400 ° C. or less for 5 hours. TiO ₂ -SiO ₂ A binary composite oxide (component A) was obtained. SO in the binary composite oxide ₄ The content was 4.9% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added thereto and dissolved by heating. This solution and 12.64 kg of the binary composite oxide (component A) described above were kneaded by a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. However, the moldability was good. Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare catalyst IV.
[0033]
Example 5
Titanium sulfate crystals [TiO as titanium source ₂ The silica sol [SiO2] was dissolved in an aqueous solution of titanyl sulfate dissolved in 30.0 kg of water. ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 2.1 kg was added and mixed for 15 minutes, and 0.17 kg ammonium paratungstate crystal was further added. While maintaining the temperature below 60 ° C, 16.2 kg of 3N ammonia water was added and neutralized over 15 minutes to obtain TiO ₂ -SiO ₂ -WO ₃ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5 to 10 and aged by heating at 60 ° C. for 1 hour.
Separately, metatitanic acid slurry [TiO ₂ Concentration 30% by weight, made by Ishihara Sangyo Co., Ltd.] 32.0 kg, silica sol [SiO ₂ After adding and mixing 12.0 kg of concentration 20% by weight, trade name “Cataloid S-20L” Catalyst Kasei Kogyo Co., Ltd. over 10 minutes, 1.92 kg of 3N ammonia water was added and neutralized, and pH 9. 5 to 10 was maintained, and the mixture was heated and aged at 60 ° C. for 5 hours to prepare a composite hydroxide slurry as the y component.
The composite hydroxide slurry as the x component is mixed and stirred in the composite hydroxide slurry as the y component, and the mixture slurry is dehydrated and washed, and dried at a temperature of 400 ° C. or less for 5 hours. ₂ -SiO ₂ -WO ₃ A ternary composite oxide (component A) was obtained. SO in the binary composite oxide ₄ The content was 4.9% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added and dissolved by heating. This solution and 12.64 kg of the above-mentioned ternary composite oxide (component A) were kneaded with a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. However, the moldability was good. Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare catalyst V.
[0034]
Example 6
Titanium sulfate crystals [TiO as titanium source ₂ Silica sol [SiO2] was added to an aqueous solution of titanyl sulfate dissolved in 30.0 kg of water. ₂ Concentration of 20% by weight, trade name “Cataloid S-20L” manufactured by Catalyst Chemical Industry Co., Ltd.)] 3.0 kg was added and mixed over 15 minutes, and 16.2 kg of 3N aqueous ammonia was maintained while maintaining the temperature at 60 ° C. or lower. Add / neutralize over 15 minutes to TiO ₂ -SiO ₂ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5 to 10 and aged by heating at 60 ° C. for 1 hour.
Separately, metatitanic acid slurry [TiO ₂ Concentration 30% by weight, made by Ishihara Sangyo Co., Ltd.] 32.0 kg, silica sol [SiO ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] 11.25 kg was added and mixed over 10 minutes, and further 0.17 kg of ammonium paratungstate crystal was added and then 3N 1.92 kg of ammonia water was added and neutralized, and the pH was maintained at 9.5 to 10, and the mixture was heated and aged at 60 ° C. for 5 hours to prepare a composite hydroxide slurry as the y component.
The composite hydroxide slurry as the x component is mixed and stirred in the composite hydroxide slurry as the y component, and the mixture slurry is dehydrated and washed, and dried at a temperature of 400 ° C. or less for 5 hours. ₂ -SiO ₂ -WO ₃ A ternary composite oxide (component A) was obtained. SO in the binary composite oxide ₄ The content was 4.9% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added and dissolved by heating. This solution and 12.64 kg of the above-mentioned ternary composite oxide (component A) were kneaded with a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. However, the moldability was good. Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare catalyst VI.
[0035]
Comparative Example 1
Titanium sulfate crystals [TiO as titanium source ₂ Concentration 32% by weight, manufactured by Teika Co., Ltd.] 43.6 kg was taken, and silica sol (SiO2) was added to an aqueous solution of titanyl sulfate dissolved and diluted in 174.4 kg of water. ₂ 5.25 kg of a concentration of 20% by weight, trade name “Cataloid S-20L” manufactured by Catalytic Chemical Industry Co., Ltd.) was added and mixed for 15 minutes, and 3N ammonia water 94. Add and neutralize 16kg over 15 minutes to TiO ₂ -SiO ₂ A composite hydroxide (component x) slurry was produced, and further maintained at pH 9.5 to 10 and aged by heating at 60 ° C. for 1 hour.
This obtained TiO ₂ -SiO ₂ After dehydrating and washing the composite hydroxide slurry, the slurry is dried at a temperature of 400 ° C. or lower for 5 hours to obtain TiO 2. ₂ -SiO ₂ A binary complex oxide (component x) was obtained. SO in the binary composite oxide ₄ The content was 6.9% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added thereto and dissolved by heating. This solution and the above-mentioned binary composite oxide (component X) 12.64 kg are kneaded by a kneader, and further added with molding aids such as clay and glass fiber, kneaded and then extruded into a honeycomb. However, the formability was poor and it was difficult to extrude into a honeycomb shape. However, the sample for activity measurement was somehow molded, and the obtained molding was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare catalyst VII.
[0036]
Comparative Example 2
Metatitanic acid slurry [TiO ₂ Concentration 30% by weight, manufactured by Ishihara Sangyo Co., Ltd.] 40.0 kg and silica sol [SiO ₂ Concentration 20 wt%, trade name “Cataloid S-20L” manufactured by Catalyst Kasei Kogyo Co., Ltd.] After mixing 15.0 kg, 10.8 kg of 3N ammonia water was added to adjust the pH of the slurry to 9.5. A composite hydroxide (y component) slurry was obtained. The composite hydroxide slurry was heated and aged for 1 hour while maintaining a pH of 9.5 to 10 at a temperature of 60 ° C., then the composite hydroxide slurry was dehydrated and washed, dried at a temperature of 400 ° C. or less for 5 hours, and TiO 2. ₂ -SiO ₂ A binary composite oxide (Y component) was obtained. SO in the binary composite oxide ₄ The content was 4.2% by weight.
Next, 0.3 kg of monoethanolamine and 3.0 kg of water were mixed, and 0.205 kg of ammonium metavanadate was added thereto and dissolved by heating. This solution and 12.64 kg of the binary composite oxide (Y component) described above were kneaded with a kneader, and further kneaded and kneaded with a molding aid such as clay and glass fiber, and then extruded into a honeycomb shape. . Next, the molded product was dried at 110 ° C. and then calcined at 600 ° C. in a muffle furnace to prepare catalyst VIII.
[0037]
Examples of catalyst use
The denitration performance was evaluated for the catalysts I to VIII of Examples 1 to 6 and Comparative Examples 1 to 3.
In the denitration performance test, a honeycomb reactor (cell pitch 7.4 mm, wall thickness 1.0 mm) having a length of 300 mm cut into 3 × 3 cells was filled into a flow reactor and the denitration rate was measured under the following conditions. . Denitration rate is determined by NOx in the gas before and after contacting the catalyst. _X Was measured with a chemirmi-type nitrogen oxide analyzer and determined by the following formula.
[Expression 1]
Denitration rate (volume%) = {[NO in non-contact gas _X (Volume ppm)-NO in contact gas _X (Volume ppm)] / NO in non-contact gas _X (Volume ppm)} × 100
<Test conditions>

Also, SO _X The oxidation ability test was performed by filling a flow reactor with a 300 mm long 3 × 3 cut from a honeycomb catalyst, and performing SO treatment under the following conditions. ₃ Conversion was measured.
SO ₃ The conversion rate is the SO in the gas before and after contact with the catalyst. ₂ Concentration is infrared type SO ₂ It measured with the gas concentration meter, and calculated | required by following Formula.
[Expression 2]
SO ₃ Conversion (volume%) = {[SO in non-contact gas ₂ (Volume ppm)-SO in contact gas ₂ (Volume ppm)] / SO in non-contact gas ₂ (Volume ppm)} × 100
<Test conditions>

The evaluation results are shown in Table 2.
[0038]
[Table 2]

(Note) V ₂ O ₅ Is 1.0% by weight on an external basis.
[0039]
【The invention's effect】
As is apparent from the table, the catalyst of the present invention has a very low SO ratio while maintaining a high denitration rate. ₃ It can be seen that this is an excellent catalyst showing the conversion rate. In addition, SO ₃ When the conversion rate is 0.20% or less, the difference of ± 0.01% is a significant difference. A catalyst having such performance is extremely effective as a catalyst for treating boiler exhaust gas using a fuel containing a large amount of sulfur component. Moreover, since the catalyst of the present invention has good moldability even when formed into a honeycomb shape, the productivity as an industrial catalyst is also high.

Claims

A composite obtained by adding and neutralizing a basic aqueous solution to a mixed aqueous solution of a soluble titanium compound, soluble silicon compound and / or silica sol, or a mixed aqueous solution of a soluble titanium compound, soluble tungsten compound, soluble silicon compound and / or silica sol. Add basic aqueous solution to hydroxide (x component) slurry, mixed aqueous solution of metatitanic acid slurry and soluble silicon compound and / or silica sol, or mixed aqueous solution of metatitanic acid slurry, soluble tungsten compound, soluble silicon compound and / or silica sol -A composite hydroxide (component A) obtained by neutralization and an obtained composite oxide (component A) and an oxide of at least one metal selected from the group consisting of vanadium, molybdenum and tungsten Contains (B component) Nitrogen oxide removing catalyst.

The catalyst for removing nitrogen oxides according to claim 1, wherein the amount of the composite oxide derived from the x component contained in the composite oxide (component A) is in the range of 5 to 30 wt%.

The composition of the composite oxide (component A) is in the range of 75 to 90% by weight as titanium oxide, 10 to 20% by weight as silicon oxide, and 0 to 5% by weight as tungsten oxide. Or the catalyst for nitrogen oxide removal of 2.

The composite oxide (A component) oxide basis either nitrogen oxide removing catalyst according to claims 1 to 3, characterized in that it contains 1 to 10 wt% of sulfate group as SO _4.

The nitrogen oxide according to any one of claims 1 to 4, comprising 85 to 99.9 wt% of the composite oxide (component A) and 0.1 to 15 wt% of the metal oxide (component B). Removal catalyst.

(1) Addition and neutralization of a basic aqueous solution to a mixed aqueous solution of a soluble titanium compound, a soluble silicon compound and / or silica sol, or a mixed aqueous solution of a soluble titanium compound, soluble tungsten compound, soluble silicon compound and / or silica sol to form a composite Obtain a slurry of hydroxide (component x), (2) Separately, mixed aqueous solution of metatitanic acid slurry and soluble silicon compound and / or silica sol, or mixed metatitanic acid slurry, soluble tungsten compound, soluble silicon compound and / or silica sol A basic aqueous solution is added to the aqueous solution and neutralized to obtain a composite hydroxide (y component) slurry, and (3) the composite hydroxide slurry of the x component and the composite hydroxide of the y component described above. After mixing with the slurry, washing and drying the composite hydroxide (a composition) ) Or a composite oxide (component A) is loaded with a precursor (component b) of at least one metal oxide selected from the group consisting of vanadium, molybdenum and tungsten, dried and fired. A method for producing a catalyst for removing nitrogen oxides.