JP3858997B2 - Exhaust gas purification catalyst and exhaust gas purification device - Google Patents

Description

【０１０８】
【表２】

【０１０９】
図１は、コート層構造の概略図である。
【０１１０】
各実施例、参考例及び比較例について、下記評価条件でＨＣ浄化特性評価（ＥＣモード、ＬＡ−４のＡ−ｂａｇ）を、図２の評価システムを用いて行った。その結果を表３及び表４に示す。
【０１１１】
耐久条件
エンジン排気量 ３０００ｃｃ
燃料 ガソリン（Ｐｂ＝１２ｍｇ／ｕｓｇ，Ｓ＝３００ｐｐｍ）
触媒入口ガス温度 ６５０℃
耐久時間 １００時間
性能評価条件
触媒容量（片バンク） 三元触媒１．３Ｌ＋ＨＣ吸着触媒２．６Ｌ
評価車両 日産自動車株式会社製 Ｖ型６気筒 ３．３Ｌエンジン
エンジン始動時に排出される（触媒入口のガス中の）炭化水素

【０１１２】
【表３】

【０１１３】
【表４】

【０１１４】
比較例に比べ実施例は、触媒活性が高く、後述する本発明の効果を確認することができた。
【０１１５】
前段触媒例１
セリウム３モル％（ＣｅＯ_２に換算して８．７重量％）、ジルコニウム３モル％（ＺｒＯ_２に換算して６．３重量％）とランタン２モル％（Ｌａ_２Ｏ_３に換算して５．５重量％）を含有するアルミナ粉末（粉末Ａ）に硝酸パラジウム水溶液を含浸し、１５０℃で１２時間乾燥した後、４００℃で１時間焼成して、Ｐｄ担持アルミナ粉末（粉末Ｂ）を得た。この粉末ＢのＰｄ濃度は１６重量％であった。
ランタン１モル％（Ｌａ_２Ｏ_３に換算して２重量％）とジルコニウム３２モ％（ＺｒＯ_２に換算して２５重量％）を含むセリウム酸化物粉末（粉末Ｃ）に硝酸パラジウム水溶液を含浸し、１５０℃で１２時間乾燥した後、４００℃で１時間焼成して、Ｐｄ担持セリウム酸化物（Ｌａ_０．０１Ｚｒ_０．３２ＣｅＯ_{０．６７ｘ}）粉末（粉末Ｄ）を得た。この粉末ＤのＰｄ濃度は６．０重量％であった。
【０１１６】
上記粉末Ｂ５６５ｇ、粉末Ｄ３７７ｇと活性アルミナ５８．５ｇ、硝酸水溶液２０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．０Ｌ、６００セル／４ミル、ＧＳＡ３４．５ｃｍ^２／ｃｍ^３、水力直径０．９３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１００ｇ／Ｌ−担体の触媒を得た。Ｐｄ担持量は３２０．０ｇ／ｃｆ（１１．３ｇ／Ｌ）であった（触媒Ａ）。
【０１１７】
次いで、上記触媒成分担持コージェライト質モノリス担体に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた（触媒Ｂ）。
【０１１８】
前段触媒例２
上記粉末Ｂ５６５ｇ、粉末Ｄ３７７ｇと活性アルミナ５８．５ｇ、硝酸水溶液２０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量９１．７ｇ／Ｌ−担体の触媒を得た。パラジウム担持量は２９３．３ｇ／ｃｆ（１０．３６ｇ／Ｌ）であった（触媒Ｃ）。
【０１１９】
Ｚｒ３重量％を含むアルミナ粉末（粉末Ｅ）に硝酸ロジウム水溶液を含浸し、１５０℃で１２時間乾燥した後、４００℃で１時間焼成して、Ｒｈ担持アルミナ粉末（粉末Ｆ）を得た。この粉末ＦのＲｈ濃度は４．０重量％であった。
Ｌａ１モル％Ｃｅ２０モル％Ｚｒ７９モル％のジルコニウム酸化物粉末（粉末Ｇ）にジニトロジアンミン酸白金水溶液を含浸し、１５０℃で１２時間乾燥した後、４００℃で１時間焼成して、Ｐｔ担持ジルコニウム酸化物粉末（粉末Ｈ）を得た。この粉末ＨのＰｔ濃度は４．０重量％であった。
【０１２０】
上記粉末Ｆ１１７．５ｇ、粉末Ｈ１１７．５ｇと、活性アルミナ１５ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を前記Ｐｄ含有触媒成分層を担持したコージェライト質モノリス担体（触媒Ｃ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。コート量２５ｇ／Ｌ（コート量総重量１１６．７ｇ／Ｌ）−担体の触媒を得た。Ｒｈの担持量は１３．３ｇ／ｃｆ（０．４８ｇ／Ｌ）、Ｐｔの担持量は１３．３ｇ／ｃｆ（０．４８ｇ／Ｌ）であった（触媒Ｄ）。
次いで、上記触媒成分担持コージェライト質モノリス担体（触媒Ｄ）に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた（触媒Ｅ）。
【０１２１】
実施例２４
Ｈ型β−ゼオライト８００ｇ、シリカゾル１０００ｇ（固形分２０％）と純水１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．３Ｌ、２００セル／１０ミル、ＧＳＡ１９．０ｃｍ^２／ｃｍ^３、水力直径１．５３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。コート量重量２００ｇ／Ｌ−担体の触媒を得た（触媒Ｆ）。
【０１２２】
Ｌａ１モル％Ｃｅ２０モル％Ｚｒ７９モル％のジルコニウム酸化物粉末（粉末Ｇ）に硝酸ロジウム水溶液を含浸し、１５０℃で１２時間乾燥した後、４００℃で１時間焼成して、Ｒｈ担持シルコニウム酸化物粉末（粉末Ｉ）を得た。この粉末ＩのＲｈ濃度は８．０重量％であった。
上記粉末Ｂ５００ｇ、粉末Ｄ８０ｇ、粉末Ｉ３５３ｇ、粉末Ａ４７ｇと活性アルミナ２０ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を上記触媒Ｆに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１００ｇ／Ｌ（総重量３００ｇ／Ｌ−担体）の触媒Ｇを得た。触媒Ｇのパラジウム担持量は２４０．０ｇ／ｃｆ（８．４８ｇ／Ｌ）、ロジウム担持量は８０．０ｇ／ｃｆ（２．８３ｇ／Ｌ）であった。 次いで、上記触媒Ｇに酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた（触媒Ｈ）。
【０１２３】
実施例２５
Ｈ型β−ゼオライト８００ｇに代わり、Ｈ型β−ゼオライト５００ｇ、ＺＳＭ５を１００ｇ、ＵＳＹ１００ｇ、Ｙ型５０ｇ、モルデナイト５０ｇを用いた以外は、実施例２４と同様にして触媒Ｉを得た。
【０１２４】
実施例２６
Ｈ型β−ゼオライト８００ｇに代わり、ホウ素０．５重量％、カルシウム０．１重量％を含むＨ型β−ゼオライト８００ｇを用いた以外は、実施例２４と同様にして触媒Ｊを得た。
【０１２５】
実施例２７
Ｈ型β−ゼオライト８００ｇに代わり、リン０．５重量％、マグネシウム０．１重量％を含むＨ型β−ゼオライト６００ｇと、ホウ素０．５重量％、カルシウム０．１重量％を含むＺＳＭ５を１００ｇと、リン０．５重量％、カルシウム０．１重量％を含むＵＳＹ１００ｇを用いた以外は、実施例２４と同様にして触媒Ｋを得た。
【０１２６】
実施例２８
リン酸２水素アンモニウム２０ｇを純水１５００ｇに溶解した溶液に、Ｈ型β−ゼオライト１０００ｇを加え、更に、２５％アンモニア水を滴下しｐＨを９．０に調整した後、２４時間攪拌・混合した。
この混合溶液からβ−ゼオライトを濾取し、１２０℃で２４時間乾燥後、空気中、６５０℃で２時間焼成し粉末Ｊを得た。更に、この粉末Ｊに硝酸パラジウム溶液を含浸し、Ｐｄ１重量％、Ｐ０．５重量％を含む粉末Ｋを得た。この粉末Ｋ８００ｇ、シリカゾル１０００ｇ（固形分２０％）と硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．３Ｌ、２００セル／１０ミル、ＧＳＡ１９．０ｃｍ^２／ｃｍ^３、水力直径１．５３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。コート量重量２００ｇ／Ｌ−担体の触媒を得た（触媒Ｌ）。Ｐｄの担持量は４５．３ｇ／ｃｆ（１．６ｇ／Ｌ）。
上記粉末Ｂ５００ｇ、粉末Ｄ８０ｇ、粉末Ａ３０ｇと活性アルミナ１５ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を上記触媒Ｌに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、触媒Ｍを得た。
更に、上記粉末Ｉ３５３ｇ、粉末Ａ１７ｇと活性アルミナ５ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を上記触媒Ｍに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１００ｇ／Ｌ（総重量３００ｇ／Ｌ−担体）の触媒Ｎを得た。触媒Ｍのパラジウム担持量は２８５．４ｇ／ｃｆ（１０．０８ｇ／Ｌ）、ロジウム担持量は８０ｇ／ｃｆ（２．８３ｇ／Ｌ）であった。
次いで、上記触媒成分担持コージェライト質モノリス担体（触媒Ｎ）に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた（触媒Ｏ）。
【０１２７】
実施例２９
Ｈ型β−ゼオライト８００ｇに代わり、パラジウム０．２８重量％、リン０．２重量％、ホウ素０．３重量％、マグネシウム０．１重量％、カルシウム０．１重量％を含むＨ型β−ゼオライト５００ｇと、Ｐｔ０．３３重量％、カルシウム０．１重量％を含むＺＳＭ５を１００ｇと、パラジウム０．２８重量％、リン０．２重量％を含むＵＳＹ２００ｇ、Ｐｔ０．３３重量％、ホウ素０．１重量％、マグネシウム０．１重量％を含むモルデナイト１００ｇを用い、コージェライト質モノリス担体（２００セル／１０ミル、ＧＳＡ１９．０ｃｍ^２／ｃｍ^３、水力直径１．５３ｍｍ）を用いた以外は、実施例１と同様にして触媒Ｐを得た。コート量２００ｇ／Ｌ、Ｐｄの担持量は１１．１ｇ／ｃｆ（０．３９ｇ／Ｌ）、Ｐｔの担持量は３．７ｇ／ｃｆ（０．１３ｇ／Ｌ）であった。
【０１２８】
上記粉末Ａ３０ｇ、粉末Ｂ５００ｇ、粉末Ｄ８０ｇと活性アルミナ２０ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を前記触媒Ｐに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成し、触媒Ｑを得た。
上記粉末Ｆ１７６ｇ、粉末Ｈ１１７ｇ、粉末Ｉ１７７ｇと活性アルミナ３０ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を前記触媒Ｑに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。次いで、上記触媒成分担持コージェライト質モノリス担体に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた（触媒Ｒ）。コート量５０ｇ／Ｌ（総重量２５０ｇ／Ｌ−担体）、Ｐｄの担持量は２５１．２ｇ／ｃｆ（８．８７ｇ／Ｌ）、Ｐｔ担持量１６．９ｇ／ｃｆ（０．６０ｇ／Ｌ）、Ｒｈ担持量４０．０ｇ／ｃｆ（１．４２ｇ／Ｌ）であった（触媒Ｒ）。
【０１２９】
前段触媒例３
粉末Ｂ１３２４ｇ、粉末Ｆ１０６ｇ、粉末Ｈ２７ｇと活性アルミナ４３ｇ、硝酸水溶液２０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．０Ｌ、９００セル／２ミル、ＧＳＡ４３．６ｃｍ^２／ｃｍ^３、水力直径０．７８ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１５０ｇ／Ｌ−担体の触媒を得た。次いで、上記触媒に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた。
パラジウム担持量は６００．０ｇ／ｃｆ（２１．２ｇ／Ｌ）、白金担持量は３．０ｇ／ｃｆ（０．１１ｇ／Ｌ）、ロジウム担持量は１２．０ｇ／ｃｆ（０．４２ｇ／Ｌ）であった（触媒Ｓ）。
【０１３０】
実施例３０
Ｈ型β−ゼオライト８００ｇ、粉末Ｉ８８．３ｇ、粉末Ｅ１６１．５ｇ、シリカゾル１０００ｇ（固形分２０％）と純水１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．３Ｌ、２００セル／１０ミル、ＧＳＡ１９．０ｃｍ^２／ｃｍ^３、水力直径１．５３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。コート量重量２５０ｇ／Ｌ−担体の触媒を得た（触媒Ｔ）。
【０１３１】
上記粉末Ｂ５００ｇ、粉末Ｄ８０ｇ、粉末Ｉ１７６．５ｇ、粉末Ｅ２０３ｇ、粉末Ａ４０ｇと活性アルミナ２０ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を上記触媒Ｔに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１００ｇ／Ｌ（総重量３００ｇ／Ｌー担体）、パラジウム担持量は２４０．０ｇ／ｃｆ（８．４８ｇ／Ｌ）、ロジウム担持量は８０．０ｇ／ｃｆ（２．８３ｇ／Ｌ）の触媒Ｕを得た。
次いで、上記触媒Ｕに酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた（触媒Ｖ）。
【０１３２】
比較例８
コージェライト質モノリス担体（１．３Ｌ、６００セル／２ミル、ＧＳＡ３６．２ｃｍ^２／ｃｍ^３、水力直径０．９７ｍｍ）を用いた以外、実施例２４と同様に触媒Ｗを得た。
【０１３３】
比較例９
コージェライト質モノリス担体（１．３Ｌ、９００セル／４ミル、ＧＳＡ４１．１ｃｍ^２／ｃｍ^３、水力直径０．７４ｍｍ）を用いた以外、実施例２４と同様に触媒Ｘを得た。
【０１３４】
比較例１０
Ｈ型β−ゼオライト８００ｇ、シリカゾル１０００ｇ（固形分２０％）と純水１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．３Ｌ、２００セル／１０ミル、ＧＳＡ１９．０ｃｍ^２／ｃｍ^３、水力直径１．５３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。コート量重量２０ｇ／Ｌ−担体の触媒Ｙを得た。
触媒Ｆの代わりに、触媒Ｙを用いた以外、実施例２４と同様にして触媒Ｚを得た。
【０１３５】
比較例１１
Ｈ型β−ゼオライト８００ｇ、シリカゾル１０００ｇ（固形分２０％）と純水１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．３Ｌ、２００セル／１０ミル、ＧＳＡ１９．０ｃｍ^２／ｃｍ^３、水力直径１．５３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。コート量重量３００ｇ／Ｌ−担体の触媒ＡＡを得た。
粉末Ｊ（粉末ＡにＰｄを担持したアルミナ粉末、Ｐｄ濃度５０重量％）１６０．０ｇ、粉末Ｋ（粉末ＣにＰｄを担持したセリウム酸化物粉末、Ｐｄ濃度２８重量％）１７ｇ、粉末Ａｇ、粉末Ｌ（粉末ＧにＲｈを担持したジルコニウム酸化物粉末、Ｒｈ濃度２５重量％）１１３．０ｇ、活性アルミナ１０ｇ、硝酸水溶液５００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を上記触媒ＡＡに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量３０ｇ／Ｌ（総重量３３０ｇ／Ｌ−担体）、パラジウム担持量は２４０．０ｇ／ｃｆ（８．４８ｇ／Ｌ）、ロジウム担持量は８０．０ｇ／ｃｆ（２．８３ｇ／Ｌ）の触媒ＢＢを得た。
次いで、上記触媒Ｕに酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた触媒ＣＣを得た。
【０１３６】
比較例１２
上記粉末Ｂ６５９ｇ、粉末Ｄ８０ｇ、粉末Ｉ３５．３ｇ、粉末Ａ２０６ｇと活性アルミナ２０ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液を上記触媒Ｆに付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１００ｇ／Ｌ（総重量３００ｇ／Ｌ−担体）の触媒ＤＤを得た。触媒ＤＤのパラジウム担持量は３１２．０ｇ／ｃｆ（１１．０２ｇ／Ｌ）、ロジウム担持量は８．０ｇ／ｃｆ（０．２８ｇ／Ｌ）であった。
次いで、上記触媒ＤＤに酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた触媒ＥＥを得た。
【０１３７】
比較例１３
上記粉末Ｂ１６２ｇ、粉末Ｄ８０ｇ、粉末Ｉ１５ｇ、粉末Ａ７２３ｇと活性アルミナ２０ｇ、硝酸水溶液１０００ｇを磁性ボールミルに投入し、混合・粉砕してスラリーを得た。このスラリー液をコージェライト質モノリス担体（１．０Ｌ、９００セル／２ミル、ＧＳＡ４３．６ｃｍ^２／ｃｍ^３、水力直径０．７８ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを除去・乾燥し、４００℃で１時間焼成した。この作業を２度行い、コート量重量１００ｇ／Ｌの触媒を得た。触媒ＤＤのパラジウム担持量は７３．３ｇ／ｃｆ（２．５９ｇ／Ｌ）、ロジウム担持量は６．７ｇ／ｃｆ（０．２４ｇ／Ｌ）であった。
次いで、上記触媒に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた触媒ＦＦを得た。
【０１３８】
上記実施例２４〜３０、前段触媒例１〜３及び比較例８〜１３で得られた排気ガス浄化用触媒の仕様を表５及び６に示す。
【０１３９】
【表５】

【０１４０】
【表６】

【０１４１】
試験例
前記実施例２４〜３０、前段触媒例１〜３及び比較例８〜１３で得られた排気ガス浄化用触媒を、以下の耐久条件により耐久を行った。

【０１４２】
上記条件で耐久した実施例２４〜３０、前段触媒例１〜３及び比較例８〜１３の触媒を用い、実施例３１〜５０、比較例１４〜２５について、下記評価条件でＨＣ浄化特性評価（ＥＣモード、ＬＡ−４のＡ−ｂａｇ）を、図３〜８のシステム（排気ガス浄化装置）を用いて行った。その結果を表７〜表１０に示す。
【０１４３】
性能評価条件
触媒容量（片バンク） 三元触媒２．０Ｌ（１．０Ｌ＋１．０Ｌ）＋ＨＣ吸着触媒１．３Ｌ〜２．６Ｌ
評価車両 日産自動車株式会社製 Ｖ型６気筒 ３．３Ｌエンジン
エンジン始動時に排出される（触媒入口のガス中の）炭化水素

【０１４４】
【表７】

【０１４５】
【表８】

【０１４６】
【表９】

【０１４７】
【表１０】

【０１４８】
実施例５５
β−ゼオライト粉末（Ｈ型、Ｓｉ／２Ａｌ＝２５）７００ｇ、出光製ＺＳＭ５（Ｈ型、Ｓｉ／２Ａｌ＝３０）粉末２００ｇ、シリカゾル（固形分２０％）１００ｇ、純粋１５００ｇを磁性ボールミルに投入し、混合粉砕してスラリー液を得た。このスラリー液をコージェライト質モノリス担体（３００セル／６ミル、ＧＳＡ２４．１ｃｍ^２／ｃｍ^３、水力直径１．３ｍｍ）に付着させ、空気流にてセル内の余剰のスラリーを取り除いて乾燥し、４００℃で１時間焼成した。この時の塗布量として、焼成後に１５０ｇ／Ｌになるまでコーティング作業を繰り返し、触媒−ａを得た。
【０１４９】
Ｃｅ３ｍｏｌ％を含むアルミナ粉末に、ジニトロジアミンパラジウム水溶液を含浸或いは高速攪拌中で噴霧し、１５０℃で２４時間乾燥した後、４００℃で１時間焼成し、次いで、６００℃で１時間焼成し、Ｐｄ担持アルミナ粉末（粉末ａ）を得た。この粉末ａのＰｄ濃度は６．２３重量％であった。粉末ａには、ランタン、ジルコニウム、ネオジウム等が含まれてもよい。
【０１５０】
Ｌａ１モル％とＺｒ３２モル％含有セリウム酸化物粉末に、ジニトロジアミンパラジウム水溶液を含浸あるいは高速攪拌中で噴霧し、１５０℃で２４時間乾燥した後、４００℃で１時間焼成し、次いで、６００℃で１時間焼成し、Ｐｄ担持セリウム酸化物粉末（粉末ｂ）を得た。この粉末ａのＰｄ濃度は、２．０重量％であった。
【０１５１】
上記Ｐｄ担持アルミナ粉末（粉末ａ）５６２ｇ、Ｐｄ担持セリウム酸化物粉末（粉末ｂ）２８８ｇ、硝酸酸性アルミナゾル９５０ｇ（ベーマイトアルミナ１０重量％に１０重量％の硝酸を添加することによって得られたゾル）及び純水１０００ｇを磁性ボールミルに投入し、混合粉砕してスラリー液を得た。このスラリー液を上記コート触媒−ａに付着させ、空気流にてセル内の余剰のスラリーを取り除いて乾燥し、４００℃で１時間焼成し、コート層重量６０ｇ／Ｌを塗布し、触媒−ｂを得た。
【０１５２】
Ｚｒ３重量％を含むアルミナ粉末に、硝酸ロジウム水溶液を含浸或いは高速攪拌中で噴霧し、１５０℃で２４時間乾燥した後、４００℃で１時間焼成し、次いで、６００℃で１時間焼成し、Ｒｈ担持アルミナ粉末（粉末ｃ）を得た。この粉末ｃのＲｈ濃度は１．２５重量％であった。
【０１５３】
上記Ｒｈ担持アルミナ粉末（粉末ｃ）３６６ｇ、Ｌａ１モル％とＣｅ２０モル％を含むジルコニウム酸化物粉末３００ｇ、硝酸酸性アルミナゾル１１３５ｇを磁性ボールミルに投入し、混合粉砕してスラリー液を得た。このスラリー液を上記コート触媒−ｂに付着させ、空気流にてセル内の余剰のスラリーを取り除いて乾燥し、４００℃で１時間焼成し、コート層重量４０ｇ／Ｌを塗布し、触媒を得た。
上記セリウム酸化物粉末、アルミナ粉末にはランタン、ネオジウム等が含まれてもよい。
次いで、上記触媒成分担持コージェライト質モノリス担体に酢酸バリウム溶液を付着させた後、４００℃で１時間焼成し、ＢａＯとして１０ｇ／Ｌを含有させた。
【０１５４】
実施例５６
β−ゼオライト粉末（Ｈ型、Ｓｉ／２Ａｌ＝２５）５００ｇ、出光製ＺＳＭ５（Ｈ型、Ｓｉ／２Ａｌ＝３０）粉末４００ｇを用いた以外は、実施例１と同様にして排気ガス浄化用触媒を得た。
【０１５５】
実施例５７
出光製ＺＳＭ５（Ｈ型、Ｓｉ／２Ａｌ＝３０）粉末に、Ａｇ，Ｐを逐次含浸、乾燥、焼成により担持したＡｇ−Ｐ担持ＺＳＭ５粉末（各金属濃度０．２重量％、総金属濃度０．４重量％）と、β−ゼオライト（Ｈ型、Ｓｉ／２Ａｌ＝２５）にＡｇ，Ｐを逐次含浸、乾燥、焼成により担持したＡｇ−Ｐ担持β−ゼオライト粉末（各金属濃度０．２重量％、総金属濃度０．４重量％）を用いた以外は、実施例１と同様にして排気ガス浄化用触媒を得た。
【０１５６】
実施例５８
出光製ＺＳＭ５（Ｈ型、Ｓｉ／２Ａｌ＝３０）粉末に、Ｐｄ，Ｍｇ，Ｃａ，Ｙ，Ｌａ，Ｎｄ，Ｂ，Ｚｒを逐次含浸、乾燥、焼成により担持したＰｄ−Ｍｇ−Ｃａ−−Ｌａ−Ｎｄ−Ｂ−Ｚｒ担持ＺＳＭ５粉末（各金属濃度０．０５重量％、総金属濃度０．４重量％）と、β−ゼオライト（Ｈ型、Ｓｉ／２Ａｌ＝２５）にＳｒ，Ｂａ，Ａｇ，Ｃｅ，Ｎｄ，Ｐを逐次含浸、乾燥、焼成により担持したＭｇ，Ｙ，Ｎｄ、Ｚｒ担持β−ゼオライト粉末（各金属濃度０．０５重量％、総金属濃度０．３重量％）を用いた以外は、実施例１と同様にして排気ガス浄化用触媒を得た。
【０１５７】
比較例２７
出光製ＺＳＭ５（Ｈ型、Ｓｉ／２Ａｌ＝３０）粉末９００ｇとした以外は、実施例５５と同様にして排気ガス浄化用触媒を得た。
【０１５８】
比較例２８
β−ゼオライト粉末（Ｈ型、Ｓｉ／２Ａｌ＝２５）粉末９００ｇとした以外は、実施例５９と同様にして排気ガス浄化用触媒を得た。
【０１５９】
【発明の効果】
以下、まず第一の発明の効果について総括的に説明する。
（１）ゼオライト種の最適化
ゼオライトを用いたＨＣ吸着触媒では、排気ガス中のＨＣ種分布とゼオライトの有する細孔径との間に相関があるため、最適な細孔径を持つゼオライトを選定する必要がある。 従来は、ＭＦＩ（ＺＳＭ５）をメインに、他の細孔径を有すゼオライト（例えば、ＵＳＹ等）をブレンドし細孔分布を調整していたが、耐久後にはゼオライト種によって細孔径の歪みや吸着・脱離特性が異なるため、排気ガスＨＣ種の吸着が不十分であるという問題点があった。
本発明では、２種類の細孔径を持った、耐久性に優れたβ−ゼオライトを主成分として採用することで、耐久による歪みも少なく、初期から耐久後まで細孔分布が広く保持できるため、従来に比べて吸着・脱離特性が向上する。更に２種以上のゼオライト種を組み合わせることにより、ゼオライト細孔径の分布を更に広げる効果が得られる。
すなわち、本発明においてはＺＳＭ５の種結晶としてモルデナイトを用いるため、通常のＺＳＭ５に比べ、細孔内部の奥行きが広い。このＺＳＭ５をＨＣ吸着素材として用いた場合、細孔内部へのＨＣ拡散速度が遅い（細孔の入口に分子径の大きいＨＣが来ると他のＨＣの拡散が阻害され、短時間で効率良くコールドＨＣを吸着することはできない）ため吸着性能は劣る。しかし一旦、細孔内部へ拡散して入ったＨＣは外部へ抜け難くなる（脱離が遅い）。本発明では、このＺＳＭ５とβ−ゼオライトを組合せることによって、吸着−脱離特性に優れる自動車用のＨＣ吸着材を開発した。
【０１６０】
（２）三元貴金属種（触媒成分種）の最適化
従来では、Ｒｈ、Ｐｔ、Ｐｄ等の貴金属種を同一層に共存させた仕様や、Ｒｈ層とＰｄ層を塗り分けた仕様等が提案されていた。
本発明では、ゼオライト層の上にＰｄ及びＲｈの共存層か、または、ゼオライト層の上にＰｄ層、その上にＲｈ層を設け、どちらか一方或いは両層にＰｔを添加できる仕様とした。
ゼオライトの上にＨＣ低温活性に優れるＰｄ層を設けることで、ゼオライトから脱離してくるＨＣを優先的に浄化でき、Ｐｄ層にＲｈを共存、または、その上にＲｈ層を設けることにより、理論空燃比より僅かにリッチ雰囲気にシフトしたガスが流れても、ＨＣ、ＣＯ、ＮＯｘ がバランス良く浄化できる。更に、Ｐｔを添加することで、耐被毒性の向上が得られる。
【０１６１】
（３）ゼオライト層＋三元貴金属層のコート層構造の最適化
従来では、ゼオライト層（ＨＣ吸着材層）と三元層（触媒成分層）のコート層比率やコート層を担持するモノリス担体のＧＳＡに関しては特に提示してなかったが、ＨＣ吸着触媒では、ゼオライト層と三元層の構造が最適でないと、ＨＣ吸着・脱離・浄化のサイクルが有効に行われないという問題点があった。
本発明では、ゼオライト層と三元層のコート層比率を、重量比で９：１〜１：４の割合とし、更に、コート層を設けるモノリス担体のＧＳＡを１０ｃｍ^２／ｃｍ^３〜３５ｃｍ^２／ｃｍ^３の範囲に規定することによって、前記ＨＣ吸着・脱離・浄化のバランスが良い仕様にしている。すなわち、ゼオライト層に対して三元層の割合が多く成り過ぎると、下層に配置されたゼオライト層へのガス拡散が悪くなり、ゼオライト量に見合った十分な吸着性能が得られない。一方、三元層の割合が少ないと、脱離してくるＨＣの酸化性能及び排気ガスの浄化性能が十分に得られなくなる。また、ＧＳＡが大きく成り過ぎると、ゼオライト層のＨＣ保持力が小さくなり、上部に配置された三元層で十分な浄化性能が得られない。また、ＧＳＡが小さいと、排気ガスの浄化性能が十分に得られなくなる。
【０１６２】
請求項１記載の排気ガス浄化用触媒は、ＨＣ、ＣＯ、ＮＯｘの浄化性能をバランス良く行うことができる。更に、上記効果に加えて、モノリス担体セル内を通過及びコート層内に拡散する排気ガスの拡散性（速度）を制御し、ＨＣの浄化性能を向上できる。更に、ＨＣの脱離を遅延化しＨＣの浄化性能を向上できる。
【０１６３】
請求項４記載の排気ガス浄化用触媒は、上記効果に加えて、更に、ＨＣの脱離を遅延化し炭化水素の浄化性能を向上できる。
【０１６４】
請求項５記載の排気ガス浄化用触媒は、上記効果に加えて、更に、ＨＣの脱離を遅延化し炭化水素の浄化性能を向上できる。
【０１６５】
請求項６記載の排気ガス浄化用触媒は、ＨＣ、ＣＯ、ＮＯｘの浄化性能をバランス良く行うことができる。更に、上記効果に加えて、モノリス担体セル内を通過及びコート層内に拡散する排気ガスの拡散性（速度）を制御し、ＨＣの浄化性能を向上できる。
【０１６６】
請求項７記載の排気ガス浄化用触媒は、上記効果に加えて、更に、ＨＣの浄化性能を向上できる。
【０１６７】
請求項８記載の排気ガス浄化用触媒は、上記効果に加えて、更にＨＣの浄化性能を向上できる。
更に、アルカリ金属またはアルカリ土類金属を含有せしめているので、貴金属のシンタリングを抑制するため、低温活性や浄化性能を更に向上させる効果を奏する。
【０１６８】
請求項９記載の排気ガス浄化用触媒は、上記効果に加えて、多種のＨＣを有効に吸着できる。
【０１６９】
請求項１０記載の排気ガス浄化用触媒は、上記効果に加えて、吸着可能なＨＣ種の範囲が広くなり、より多種のＨＣを有効に吸着できる。
【０１７０】
請求項１１記載の排気ガス浄化装置は、上記効果に加えて、細孔径の異なる種々のＨＣ吸着材を組み合わせることにより、エンジン始動直後の低温時に排出されるＨＣ種を高い効率で吸着し、ＨＣ吸着能を向上できる。
【０１７１】
請求項１２記載の排気ガス浄化用触媒は、上記効果に加えて、吸着特性や脱離抑制能を更に向上することができる。
【０１７２】
請求項１３記載の排気ガス浄化用触媒は、エンジン始動直後の低温時に排出されるＨＣ種を高い効率で吸着し、しかも、耐久後の構造変化や性能劣化が小さいため、脱離速度の遅延化を図ることができる。
【０１７３】
請求項１４記載の排気ガス浄化用触媒は、上記効果に加えて、更に耐被毒性を向上することができる。
【０１７４】
請求項１５記載の排気ガス浄化用触媒は、上記効果に加えて、更に、ＨＣの浄化性能を向上できる。
【０１７５】
請求項１６記載の排気ガス浄化用触媒は、上記効果に加えて、耐久後のロジウム化学状態変化による触媒性能の低下を抑制できる。
【０１７６】
請求項１７記載の排気ガス浄化用触媒は、上記効果に加えて、触媒成分の還元に起因する触媒性能の低下を抑制できる。
【０１７７】
請求項１８記載の排気ガス浄化用触媒は、上記効果に加えて、耐久後の構造安定性、及びパラジウムの化学状態変化による触媒性能の低下を抑制できる。
【０１７８】
請求項１９記載の排気ガス浄化装置は、低温活性に優れるＰｄ含有触媒と本発明のＨＣ吸着触媒を組合せ、ＨＣ吸着触媒が吸着するＨＣ量を、エンジン始動直後の低温時に排出されるＨＣ量の１０％〜７０％に設定することによって、脱離ＨＣの浄化性能を向上できる。
【０１７９】
請求項２０記載の排気ガス浄化装置は、低温活性に優れるＰｄ含有触媒とＨＣ吸着触媒を組合せ、ＨＣ吸着触媒が吸着するＨＣ量を、エンジン始動直後の低温時に排出されるＨＣ量の３０％〜７０％に設定し、更に、下記排気ガス浄化触媒の早期活性化を促進する手段を組合せることによって、ＨＣ吸着触媒が吸着するＨＣ量を更に低減し、脱離ＨＣの浄化性能を向上できる。
【０１８０】
請求項２１記載の排気ガス浄化装置は、請求項２２記載の排気ガス浄化装置において、ＨＣ吸着触媒の前段に配置したＰｄ含有触媒（三元触媒）の早期活性化を図ることができ、ＨＣ吸着触媒が脱離するＨＣの浄化性能を向上できる。
【０１８１】
請求項２２記載の排気ガス浄化装置は、請求項２２記載の排気ガス浄化装置において、ＨＣ吸着触媒の前段に配置したＰｄ含有触媒（三元触媒）の早期活性化を図ることができ、ＨＣ吸着触媒が脱離するＨＣの浄化性能を向上できる。
【０１８２】
請求項２３記載の排気ガス浄化装置は、ＨＣ吸着触媒の上流に配置したＰｄ含有触媒（三元触媒）の早期活性化と、上記浄化性能の向上を図ることができ、脱離ＨＣの浄化性能を向上できる。
【０１８３】
請求項２４記載の排気ガス浄化装置は、上記効果に加えて、触媒成分層の温度低下を抑制でき、脱離ＨＣを効率よく浄化することができる。
【０１８４】
請求項２５記載の排気ガス浄化装置は、上記効果に加えて、触媒成分層の温度低下を抑制でき、脱離ＨＣを効率よく浄化することができる。
【０１８５】
請求項２６記載の排気ガス浄化装置は、上記効果に加えて、更に触媒成分層の温度低下を抑制や浄化性能を向上でき、脱離ＨＣを効率よく浄化することができる。
【０１８６】
請求項２７記載の排気ガス浄化装置は、上記効果に加えて、前段Ｐｄ含有触媒で未浄化の低濃度排気ガス成分（ＨＣ、ＣＯ、ＮＯｘ ）を効率よく浄化することができる。
【０１８７】
請求項２８記載の排気ガス浄化装置は、上記効果に加えて、更に、ＨＣの吸着・脱離・浄化性能を向上でき、脱離ＨＣを効率よく浄化することができる。
【０１８８】
請求項２９記載の排気ガス浄化装置は、上記効果に加えて、更に、脱離ＨＣを効率よく浄化することができる。
【図面の簡単な説明】
【図１】（ａ）は本発明の触媒のウオッシュコート層構造を示す斜視図である。（ｂ）は（ａ）の部分拡大部である。
【図２】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム１）図である。
【図３】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム２）図である。
【図４】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム３）図である。
【図５】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム４）図である。
【図６】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム５）図である。
【図７】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム６）図である。
【図８】本発明の触媒を評価するために用いたエンジンの排気系を示すシステム（評価システム７）図である。
【図９】エンジン種類毎の貴金属（ＰＭ）量とエンジンアウトミッション残存率の関係を示すグラフ（マップ）である。
【図１０】三元触媒の貴金属選択マップ作成のためのフローシートである。
【図１１】エンジンアウトエミッション残存率と時間の関係を示すグラフである。
【図１２】リーン化時間演算フローシートである。
【符号の説明】
１ 炭化水素吸着層（ＨＣ吸着材層）
２ 三元触媒層（触媒成分層）
３ ガス通過部
４ 三元触媒
５ ＨＣ吸着触媒[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purifying catalyst that purifies exhaust gas when starting an internal combustion engine.
The present invention also provides hydrocarbons (hereinafter referred to as “HC”), carbon monoxide (hereinafter referred to as “CO”), and nitrogen in exhaust gas discharged from an internal combustion engine such as an automobile at a low temperature immediately after starting the engine. In particular, the present invention relates to an exhaust gas purifying catalyst capable of efficiently purifying HC among oxides (hereinafter referred to as “NOx”) and an exhaust gas purifying apparatus including the catalyst.
[0002]
[Prior art]
In recent years, an HC adsorption catalyst using zeolite has been developed for the purpose of purifying a large amount of HC discharged in a low temperature range when the engine of an internal combustion engine is started.
The HC adsorption catalyst temporarily adsorbs and holds a large amount of exhausted HC in a low temperature range at the time of engine start where the three-way catalyst is not activated, and then the three-way catalyst is activated due to an increase in exhaust gas temperature. Sometimes HC is gradually desorbed and purified.
[0003]
By the way, in the HC adsorption catalyst using zeolite, since there is a correlation between the HC species distribution in the exhaust gas and the pore diameter of the zeolite, it is necessary to set the zeolite having the optimum pore diameter.
In the past, MFI type (ZSM5) was used as a main component, and zeolites with other pore sizes (for example, USY) were blended to adjust the pore distribution. -Since the desorption characteristics are different, there is a problem that the adsorption of the exhaust gas HC species is insufficient.
[0004]
On the other hand, as a ternary noble metal catalyst, conventionally, a specification in which noble metal species such as Rh, Pt, and Pd coexist in the same layer, a specification in which the Rh layer and the Pd layer are separately applied, and the like have been proposed. For example, as shown in JP-A-2-56247, for exhaust gas purification, a second layer mainly composed of noble metals such as Pt, Pd and Rh is provided on a first layer mainly composed of zeolite. Catalysts have been proposed.
[0005]
In addition, for the purpose of reducing HC in exhaust gas discharged at low temperatures immediately after engine start-up, HC is temporarily stored using an adsorbent, desorbed after the three-way catalyst is activated, and three-way catalyst The method of purifying by is being studied.
[0006]
Examples of the invention using such an HC adsorbent (hydrocarbon adsorbent) include, for example, JP-A-6-74019, JP-A-7-144119, JP-A-6-142457, and JP-A-5-59942. And JP-A-7-102957.
[0007]
Japanese Patent Laid-Open No. 6-74019 discloses that a bypass passage is provided in an exhaust passage, and HC discharged at the time of cold immediately after engine start is once adsorbed by an HC adsorbent disposed in the bypass passage, and then the passage is switched. After the downstream three-way catalyst is activated, a system is proposed in which part of the exhaust gas is passed through the HC adsorption catalyst, and the desorbed HC is gradually purified by the latter three-way catalyst.
[0008]
Japanese Patent Laid-Open No. 7-144119 improves the adsorption efficiency of the HC adsorbent in the middle stage by causing the former three-way catalyst to take heat during cold, and after the activation of the three-way catalyst in the former stage, We have proposed a system that facilitates the transfer of reaction heat to the latter three-way catalyst through the HC adsorbent and promotes purification by the latter three-way catalyst.
JP-A-6-142457 discloses cold HC adsorption that preheats exhaust gas containing desorbed HC with a heat exchanger and promotes purification with a three-way catalyst when HC adsorbed in a low temperature region is desorbed. A removal system is proposed.
[0009]
On the other hand, Japanese Patent Laid-Open No. 5-59942 proposes a system that slows the temperature rise of the HC adsorbent and improves the cold HC adsorption efficiency by switching the catalyst arrangement and the exhaust gas flow path by the valve.
Japanese Patent Application Laid-Open No. 7-102957 discloses that in order to improve the purification performance of the latter-stage oxidation / three-way catalyst, air is supplied between the former-stage three-way catalyst and the middle-stage HC adsorbent, and the latter-stage oxidation / three-way catalyst. We have proposed a system that promotes the activation of
[0010]
[Problems to be solved by the invention]
In the exhaust gas purification catalyst in which the ternary layer is provided on the HC adsorbent layer such as the zeolite layer as described above, the HC adsorbed on the zeolite in the low temperature range of the exhaust gas immediately after the start of the internal combustion engine has the exhaust gas temperature. The exhaust gas becomes rich when desorbing as it rises, so the three-way catalyst effective for purification in the stoichiometric air-fuel ratio region does not work sufficiently, making it impossible to achieve a well-balanced purification of HC, CO, and NOx There's a problem.
In the past, the coating layer ratio between the zeolite layer and the ternary layer was not particularly indicated. However, in the HC adsorption catalyst, if the structure of the zeolite layer and the ternary layer is not optimal, HC adsorption / desorption / desorption There is a problem that the purification cycle is not performed effectively.
[0011]
On the other hand, in the system using the HC adsorbent described in the above-mentioned publication described in the section of [Prior Art], the durability of the HC adsorbent is insufficient. In addition, HC is desorbed before the latter three-way catalyst is activated, and the emission is deteriorated. Therefore, in order to improve the adsorption efficiency of HC adsorbent and to delay desorption, a high-temperature gas bypass method and a heat exchanger for three-way catalyst warm-up are used, but the system configuration is complicated and sufficient. The effect cannot be obtained, and the cost increases remarkably. For this reason, HC adsorbents with high durability and high adsorption efficiency are desired.
[0012]
In particular, three-way catalysts aimed at purifying HC desorbed from HC adsorbents use a large amount of precious metals to maintain high purification performance from the beginning to the end of the life, or introduce air for early activation. is doing. For this reason, a catalyst capable of obtaining high performance even if the amount of noble metal used is small is desired, but when the amount of noble metal is reduced, durability is insufficient, and after durability, catalytic activity and purification performance in a low temperature range There was a problem of getting worse.
[0013]
[Means for Solving the Problems]
The present invention is an integral structure type exhaust gas purification catalyst that uses a monolith carrier in comparison with such a conventional exhaust gas purification catalyst, and has an HC adsorption mainly comprising zeolite on a predetermined monolith carrier. An HC adsorbent layer containing a material is provided, and a catalyst component layer containing a predetermined noble metal as a catalyst component is further provided on the HC adsorbent layer, and the weight ratio between the HC adsorbent layer and the catalyst component layer is An object of the present invention is to solve the above problems by using an exhaust gas purifying catalyst within a predetermined range.
[0014]
  That is, the exhaust gas purifying catalyst of the present invention (hereinafter referred to as the first invention) has a GSA (Geometrical Surface Area) of 10 cm.²/ Cm³~ 35cm²/ Cm³An exhaust gas purifying catalyst comprising a monolithic carrier coated with an HC adsorbent layer containing a hydrocarbon adsorbent and a catalyst component layer containing a catalyst component in this order,
  The hydrocarbon adsorbent of the HC adsorbent layer is mainly composed of zeolite,
  The catalyst component layer contains at least one noble metal selected from the group consisting of palladium (Pd), platinum (Pt) and rhodium (Rh) as a catalyst component.And
  In the catalyst component layer, a cerium oxide containing 1 to 40 mol% in terms of metal and 60 to 98 mol% of Ce selected from the group consisting of Zr, Nd and La, and Pd are contained,
  The weight ratio of the HC adsorbent layer to the catalyst component layer is 9: 1 to 1: 4;
  The coat layer thickness is 30 μm to 400 μm, which is the sum of the thicknesses of the HC adsorbent layer and the catalyst component layer in the flat portion in the cell of the monolith carrier.
[0015]
  Further, another exhaust gas purifying catalyst of the present invention (hereinafter referred to as the second invention) has a GSA of 10 cm.²/ Cm³~ 35cm²/ Cm³An exhaust gas purifying catalyst comprising a monolithic carrier coated with an HC adsorbent layer containing a hydrocarbon adsorbent and a catalyst component layer containing a catalyst component in this order,
  The hydrocarbon adsorbent of the HC adsorbent layer is mainly composed of zeolite.And
  In the HC adsorbent layer, zirconium oxide containing 1 to 40 mol% in terms of metal of at least one selected from the group consisting of Ce, Nd and La, and Rh are contained,
  The catalyst component layer includes at least one noble metal selected from the group consisting of palladium (Pd), platinum (Pt) and rhodium (Rh) as a catalyst component;
    The weight ratio of the HC adsorbent layer to the catalyst component layer is 9: 1 to 1: 4;
  The coat layer thickness is 30 μm to 400 μm, which is the sum of the thicknesses of the HC adsorbent layer and the catalyst component layer in the flat portion in the cell of the monolith carrier.
[0016]
Furthermore, the exhaust gas purification apparatus of the present invention (hereinafter referred to as the third invention) includes Pd, Pd and Pt, or Pd and Rh in the front stage of the exhaust gas purification catalyst as described above, and has a Pd carrying concentration. A Pd-containing catalyst containing 4 to 20% by weight of Pd-supported powder and having a Pd-supporting amount per liter of catalyst of 100 g / cf (3.5 g / L) to 1000 g / cf (35.4 g / L) is disposed. And
The amount of hydrocarbon adsorbed by the exhaust gas purification catalyst is set to 70% or less of the saturated hydrocarbon adsorption amount of the exhaust gas purification catalyst.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
First, an embodiment of the present invention will be described.
The coating layer structure of the exhaust gas purifying catalyst of the present invention is the same as that of the first invention and the second invention in that a zeolite effective for HC adsorption, preferably β-zeolite, is mainly used for the HC adsorbent on a specific monolith support. An HC adsorbent layer as a component is provided, and a catalyst component layer containing at least one noble metal selected from the group consisting of Pd, Pt and Rh as a catalyst component is further provided on the HC adsorbent layer. It is a kind of “HC adsorption catalyst” described in the section of “Prior art”.
Here, the amount of β-zeolite used is preferably 10 g to 400 g per liter of the catalyst. If the amount of β-zeolite used is less than 10 g, the HC adsorption performance is not sufficiently exhibited. Conversely, if it exceeds 400 g, the HC adsorption performance and the effect of delaying desorption are saturated, which is not economically effective.
By providing a HC adsorbent layer on the monolith support and a catalyst component layer (ternary layer or three-way catalyst layer) having a so-called ternary purification ability on the monolith support, the HC adsorbed from the zeolite in the HC adsorbent layer Post-processing efficiency can be improved. Thus, since it is configured as an integrated catalyst having a multilayer structure, heat loss is less than that of the 2-brick type, the activation of the catalyst component layer is fast, and HC desorbed from the HC adsorbent is separated from the catalyst component layer. Since it can contact sufficiently, desorption HC can be purified efficiently.
[0018]
The weight ratio of the HC adsorbent layer to the catalyst component layer is 9: 1 to 1: 4. When the ratio of the catalyst component layer is larger than the specified value, gas diffusion to the HC adsorbent layer (zeolite layer) disposed in the lower layer is deteriorated, and sufficient adsorption performance cannot be obtained. If the ratio of the catalyst component layer is smaller than the specified value, the oxidization performance of the desorbed HC and the exhaust gas purification performance cannot be sufficiently obtained.
Furthermore, the monolithic carrier (specific monolithic carrier) provided with the HC adsorbent layer and the catalyst component layer has a GSA of 10 cm.²/ Cm³~ 35cm²/ Cm³It is. When GSA becomes larger than the specified value, HC desorption from the HC adsorbent layer is accelerated, and desorbed HC discharged without purification is increased. On the other hand, if it is smaller than the specified value, the diffusion of HC into the HC adsorbent layer is slow and the adsorption performance is not sufficiently developed, and the contact between the exhaust gas and the catalyst component layer is deteriorated, and the exhaust gas component purification performance is sufficient. Can not be obtained.
[0019]
  Also,1st inventionIn a preferred embodiment of the second invention, in order to improve the purification efficiency when HC adsorbed by the HC adsorbent is desorbed, a catalyst component layer (Pd containing Pd) is formed on the HC adsorbent layer. Containing catalyst component layer), and in this Pd-containing catalyst component layer, cerium oxide containing 1 to 40 mol% of metal selected from the group consisting of Zr, Nd and La and 60 to 98 mol% of cerium Contain thingsThe
[0020]
In particular, in order to improve the purification performance and durability of Pd, 1 to 40 mol% in terms of metal and 60 to 98 cerium are selected from the group consisting of Zr, Nd and La in the Pd-containing catalyst component layer. By containing cerium oxide containing mol%, the cerium oxide having a high oxygen storage capacity easily releases lattice oxygen and adsorbed oxygen in a rich atmosphere and in the vicinity of stoichiometry, so that the oxidation state of Pd can be used for purification of exhaust gas. It can be made suitable, and the fall of the catalytic ability of Pd can be suppressed.
The amount of such cerium oxide used is 5 to 100 g per liter of catalyst. If it is less than 5 g, sufficient dispersibility of the noble metal cannot be obtained, and even if it is used more than 100 g, the improvement effect is saturated and not effective.
[0021]
Furthermore, in order to improve the poisoning resistance and purification performance of Pd, one kind selected from the group consisting of Pt, Rh, Ce, Nd and La is formed on the upper part of the Pd-containing catalyst component layer in an amount of 1 to 30 mol% in terms of metal. A catalyst component layer (upper catalyst component layer) containing zirconium oxide containing 70 to 98 mol% of Zr and activated alumina can be disposed.
Zirconium oxide is suitable as the substrate on which Pt and Rh are supported in order to improve the durability of Pt and Rh. In particular, since cerium-containing zirconium oxide having a high oxygen storage capacity easily releases lattice oxygen and adsorbed oxygen in a rich atmosphere and in the vicinity of stoichiometry, the oxidation state of Pt and Rh is made suitable for purification of exhaust gas. And the decrease in the catalytic ability of Rh can be suppressed.
[0022]
The Ce content of such zirconium oxide is 0.01 mol% to 30 mol%.
If the Ce content is less than 0.01 mol%, ZrO₂ZrO of the above elements₂The improvement effect due to the oxygen storage capacity of Ce does not appear. On the other hand, when the Ce content exceeds 30 mol%, this effect is saturated or, conversely, the BET specific surface area and thermal stability are lowered. The amount of zirconium oxide used is 5 to 100 g per liter of catalyst. If it is less than 5 g, sufficient dispersibility of the noble metal cannot be obtained, and even if it is used more than 100 g, the improvement effect is saturated and not effective.
[0023]
Moreover, in order to improve the low-temperature activity of Pd, K and Ba can be contained. The content of such elements is 1 to 40 g in 1 L of the catalyst. If it is less than 1 g, it is not possible to suppress the adsorption poisoning of HCs to noble metals and sintering of Pd, and conversely, if it exceeds 40 g, no significant increase effect can be obtained, and conversely the performance is lowered.
[0024]
In another preferred embodiment of the first and second inventions, β-zeolite is included on the specific monolith support in order to effectively express the HC adsorption / desorption capability characteristics and the desorption HC purification performance. An HC adsorbent layer containing at least one zeolite as a main component is provided, and a catalyst component layer (Pd-containing catalyst component layer) containing Pd as a catalyst component is provided on the HC adsorbent layer, and this catalyst component layer Further, Rh is further contained, or a catalyst component layer (Rh-containing upper catalyst component layer) containing Rh as a catalyst component is provided on the Pd-containing catalyst component layer.
[0025]
Thus, by providing the HC adsorbent layer on the monolith support and the catalyst component layer thereon, the post-treatment efficiency of HC desorbed from the zeolite in the HC adsorbent layer can be improved.
Furthermore, Pd with excellent HC oxidation activity is arranged as a catalyst component on the HC adsorbent layer, and Rh coexists in the same layer, or an Rh-containing upper catalyst component layer is provided on the same, thereby three-way purification. Even if the inside of the catalyst component layer having a function becomes rich due to desorbed HC, the purification of HC, CO, and NOx can be performed in a well-balanced manner.
Furthermore, the influence of poisoning can be reduced by coexisting with Rh in Pd which is easily affected by poisoning due to phosphorus (P), lead (Pb) or the like, or by placing Rh inside.
In addition, since the HC adsorbent layer disposed in the lower layer has a slower warming than the upper catalyst component layer, the adsorbed HC can be held for a long time, and conversely, the catalyst component layer is warmed and activated quickly. HC has a good balance of adsorption, desorption and purification.
[0026]
Furthermore, in the preferred embodiments of the first and second inventions described above, the total coat weight of the HC adsorbent layer, the catalyst component layer (Pd-containing catalyst component layer) and the upper catalyst component layer (Rh-containing upper catalyst component layer). The ratio (the total coat weight ratio of the HC adsorbent layer and the catalyst component layer when no upper catalyst component layer is present) is 5: 1 to 1: 2.
When the ratio of the catalyst component layer exceeds the specified value, gas diffusion to the HC adsorbent layer disposed in the lower layer is deteriorated, and sufficient adsorption performance cannot be obtained. If the ratio of the catalyst component layer (and the Rh-containing upper catalyst component layer) is less than the specified value, the oxidation performance of the desorbed HC and the purification performance of the exhaust gas cannot be sufficiently obtained.
[0027]
In the exhaust gas purification catalyst according to the preferred embodiment, the HC adsorbent layer, the catalyst component layer having the three-way purification ability, and the Rh-containing upper catalyst component layer have a GSA of 10 cm.²/ Cm³~ 35cm²/ Cm³On a monolithic carrier.
When GSA becomes larger than the specified value, HC desorption from the HC adsorbent layer is accelerated, and desorbed HC discharged without purification is increased. On the other hand, if it is smaller than the specified value, the contact between the exhaust gas and the catalyst component layer is deteriorated, and the exhaust gas component purification performance cannot be sufficiently obtained.
[0028]
Furthermore, in the exhaust gas purifying catalyst according to the preferred embodiment, at least one selected from the group consisting of alkali metals and alkaline earth metals is used as an HC adsorbent layer and / or a catalyst component layer, or an HC adsorbent layer, At least one of the catalyst component layer and the Rh-containing upper catalyst component layer is impregnated and supported.
Usable alkali metals and alkaline earth metals include lithium (Li), sodium (Na), potassium (K), cesium (Cs), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba ) At least one element selected from the group consisting of:
[0029]
Alkali metal and alkaline earth metal compounds that can be used are water-soluble compounds such as oxides, acetates and hydroxides. Thereby, it becomes possible to carry | support the alkali metal and / or alkaline-earth metal which are basic elements with sufficient dispersibility in the vicinity of a noble metal.
[0030]
That is, an aqueous solution of a powder composed of an alkali metal and / or alkaline earth metal compound is impregnated into the monolith carrier carrying a washcoat component, dried, and then 200 to 600 ° C. in air and / or under air flow. It is fired at a relatively low temperature.
If the calcination temperature is less than 200 ° C., the alkali metal and alkaline earth metal compound cannot be sufficiently in the form of oxides. Conversely, if the calcination temperature exceeds 600 ° C., the effect of the calcination temperature is saturated. I can't get it.
[0031]
In the exhaust gas purifying catalysts of the first and second inventions, the zeolite component of the HC adsorbent layer has two kinds of large and small pore diameters in order to effectively adsorb HC discharged in large quantities at the time of engine start. The main component is H-type β-zeolite having a Si / 2Al ratio of 10 to 500.
The β-zeolite has higher heat resistance than other zeolites and is excellent in structural stability. In addition, while other zeolites have a narrow HC molecular diameter range effective for adsorption, β-zeolite has two types of pore sizes, large and small. Can be adsorbed effectively.
[0032]
Further, the Si / 2Al ratio of the β-zeolite is desirably in the range of 10 to 500.
When the Si / 2Al ratio is less than 10, the inhibition of adsorption of water molecules coexisting in the exhaust gas is large, and HC cannot be effectively adsorbed.
Conversely, when the Si / 2Al ratio exceeds 500, the amount of HC adsorbed decreases.
[0033]
Furthermore, in the exhaust gas purifying catalysts of the first and second inventions, the zeolite species of the HC adsorbent layer are further combined with H-type β-zeolite as a main component, MFI type, Y type, USY type, mordenite, At least one of ferrierite, A-type zeolite, X-type zeolite, AlPO4, and SAPO is used.
These zeolites change the pore distribution of the zeolite species according to the composition ratio of the HC species in the exhaust gas and improve the adsorption ability. By mixing these zeolite species together with β-zeolite, the range of adsorbable HC species is further expanded. In other words, various zeolite species that can be adsorbed can be appropriately combined with the HC species to be adsorbed.
In addition, at least one selected from the group consisting of mordenite, Y-type, USY-type, and MFI-type zeolite can be contained in an amount of 5% to 45% by weight of the total amount of HC adsorbent. When the amount is less than 5% by weight, a sufficient pore size distribution effect cannot be obtained. Conversely, when the amount is more than 45% by weight, this effect decreases the saturation or β-zeolite performance improving effect.
[0034]
In the exhaust gas purifying catalysts of the first and second inventions, the zeolite of the HC adsorbent layer includes Pd (palladium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium). , Ag (silver), Y (yttrium), La (lanthanum), Ce (cerium), Nd (neodymium), P (phosphorus), B (boron), and Zr (zirconium) are contained. It is preferable.
Zeolite has a sufficient adsorption capacity even in H type, but Pd, Mg, Ca, Sr, Ba, Ag, Y, La, Ce, Nd, P, B, Zr, etc. are ion exchange, impregnation, and immersion methods. By using a usual method such as the above, it is possible to further improve the adsorption characteristics, desorption suppression ability and durability of the zeolite.
[0035]
Furthermore, in order to improve the structural stability (heat resistance) of HC adsorbents mainly composed of β-zeolite at high temperatures, the ability to adsorb cold HC and the ability to suppress HC desorption when the temperature rises, Pt, Pd, P , B, Mg, and Ca can be included.
The content of such elements is 0.1 wt% to 10 wt% with respect to the HC adsorbent. If it is less than 0.1% by weight, a sufficient improvement effect cannot be obtained. Conversely, if it is used more than 10% by weight, the pores of the zeolite are blocked and the HC adsorption ability is lowered.
[0036]
Further, it is also preferable that Pt is further allowed to coexist in at least one of the catalyst component layer and the Rh-containing upper catalyst component layer in the exhaust gas purifying catalyst of the first and second inventions. This is because Pt can coexist with Pd or Rh to further improve toxicity resistance.
[0037]
  Furthermore,Preferred embodiment of the first inventionIn the exhaust gas purifying catalyst of the second invention, the HC adsorbent layer containing zeolite as a main component contains 1 to 40 mol% in terms of metal of at least one selected from the group consisting of Ce, Nd and La. Zirconium oxide and RhThe
  The catalyst component layer and the Rh-containing upper catalyst component layer also have sufficient desorbed HC purification performance, but the HC adsorbent layer mainly composed of zeolite is composed of Rh, Ce, Nd, and La. By including a zirconium oxide containing 1 to 40 mol% of at least one selected in terms of metal, the desorption HC purification performance can be further improved.
[0038]
Moreover, it is preferable to further contain alumina in the catalyst component layer (noble metal layer) of the exhaust gas purifying catalyst of the first and second inventions.
In particular, in order to improve the structural stability of alumina after high-temperature durability and to suppress the phase transition to α-alumina and the decrease in BET specific surface area, the alumina is at least selected from the group consisting of Ce, Zr and La. 1 type contains 1-10 mol% in conversion of a metal.
If it is less than 1 mol%, a sufficient addition effect cannot be obtained, and if it exceeds 10 mol%, the addition effect is saturated.
The amount of alumina used is 10 to 200 g per liter of catalyst. If it is less than 10 g, sufficient dispersibility of the noble metal cannot be obtained, and even if it is used in excess of 200 g, the catalyst performance is saturated and a remarkable improvement effect cannot be obtained.
[0039]
Furthermore, the catalyst component layer of the exhaust gas purifying catalyst according to the first and second inventions may further contain cerium oxide in addition to the catalyst component (noble metal).
The cerium oxide contains at least one selected from the group consisting of Zr, Nd, and La in terms of metal in an amount of 1 to 40 mol%, and the balance of Ce in a metal equivalent of 60 to 99 mol%. By containing cerium oxide, cerium oxide with high oxygen storage capacity releases lattice oxygen and adsorbed oxygen in a rich atmosphere and near the stoichiometry, making the oxidation state of noble metals suitable for purification of exhaust gas and catalytic performance Can be suppressed.
1 to 40 mol% is cerium oxide (CeO₂And at least one element selected from the group consisting of Zr, Nd and La,₂This is because the oxygen releasing ability, the BET specific surface area, and the thermal stability are significantly improved.
Less than 1 mol% CeO₂The effect of adding the above-mentioned elements does not appear as in the case of only the above, and when it exceeds 40 mol%, this effect is saturated or conversely reduced.
[0040]
Further, in the preferred embodiment of the exhaust gas purifying catalyst of the first and second inventions, the Rh-containing upper catalyst component layer further contains a zirconium oxide containing at least one selected from the group consisting of Ce, Nd and La. It can also be contained.
The zirconium oxide contains 1 to 40 mol% in terms of metal of at least one element selected from the group consisting of Ce, Nd and La, and 60 to 99 mol% in terms of metal of Zr as the balance.
The content of 1 to 40 mol% is zirconium oxide (ZrO₂) Is added with a kind of element selected from the group consisting of Ce, Nd and La.₂This is because the oxygen releasing ability, the BET specific surface area, and the thermal stability are remarkably improved.
If it is less than 1 mol%, ZrO₂The effect of adding the above-described element does not appear as in the case of only the above, and when 40 mol% is exceeded, this effect is saturated or lowered.
[0041]
By adding a powder of zirconium oxide containing at least one selected from the group consisting of Ce, Nd, and La to the Rh-containing upper catalyst component layer, the zirconium oxide is rich in the atmosphere and near the stoichiometric atmosphere. Since oxygen is released and the oxidation state of the noble metal is suitable for purification of exhaust gas, it is possible to suppress a decrease in the catalyst performance of the noble metal.
[0042]
In the exhaust gas purifying catalyst of the first and second inventions, the alkali metal and / or alkaline earth metal used includes Li, Na, K, Cs, Mg, Ca, Sr and Ba. .
When these components are contained in the catalyst component layer, the HC adsorption poisoning action in a rich atmosphere is alleviated and the sintering of noble metals is suppressed, so that the activity in a low temperature activity or a reducing atmosphere can be further improved. Its content is 1 to 40 g in 1 L of catalyst. If it is less than 1 g, HC adsorption poisoning and precious metal sintering cannot be suppressed, and if it exceeds 40 g, a significant increase effect cannot be obtained and conversely the performance deteriorates. Let
[0043]
In producing the exhaust gas purifying catalyst of the first and second inventions, an HC adsorbent layer (zeolite layer) is disposed on the inner layer side in order to effectively develop the performance of the HC adsorption layer and the catalyst component layer. The catalyst component layer (palladium layer) is the middle layer on the catalyst layer, and the Rh-containing upper catalyst component layer (rhodium layer) is further arranged on the surface layer side.
[0044]
As the noble metal (catalyst component) raw material compound in the catalyst component layer and the upper catalyst component layer, any compound can be used as long as it is water-soluble such as dinitrodiamminate, chloride and nitrate.
The removal of water can be performed by appropriately selecting from known methods such as filtration and evaporation to dryness. The initial heat treatment for obtaining the noble metal-supported powder used in the present invention is not particularly limited, but in order to support the added noble metal with good dispersibility, for example, in air and / or air circulation at a relatively low temperature of 400 ° C. to 800 ° C. It is preferred to carry out the firing under.
[0045]
Furthermore, the zeolite of the HC adsorbent layer may be impregnated with at least one selected from Pd, Mg, Ca, Sr, Ba, Ag, Y, La, Ce, Nd, P, B, and Zr. it can.
These metal compounds are dispersed on zeolite by supporting water-soluble compounds such as oxides, acetates, nitrates, and hydroxides using ordinary methods such as ion exchange, impregnation, and immersion. It becomes possible to carry with improved properties.
As a method for removing moisture after loading, drying is performed, followed by firing at a relatively low temperature of 200 to 600 ° C. in the air and / or under air flow.
If the calcination temperature is less than 200 ° C., the metal compound cannot be sufficiently in the form of an oxide. Conversely, if the calcination temperature exceeds 600 ° C., the effect of the calcination temperature is saturated and no significant difference is obtained.
[0046]
Furthermore, Pt can be contained in the catalyst component layer and the upper catalyst component layer. As the raw material compound, any water-soluble compounds such as dinitrodiamminates, chlorides and nitrates can be used.
[0047]
More preferably, the catalyst component layer (noble metal layer) is reduced by adding cerium oxide containing at least one selected from the group consisting of Zr, Nd and La to alumina powder or zirconium oxide powder. Under the atmosphere, the oxidation state of the noble metal can be more effectively maintained in a state suitable for exhaust gas purification.
[0048]
Preferably, a zirconium oxide powder containing at least one selected from the group consisting of Ce, Nd, and La can be added to the upper catalyst component layer. By adding zirconium oxide powder containing at least one selected from the group consisting of Ce, Nd, and La, the oxidation state of the noble metal is more effectively maintained in a state suitable for exhaust gas purification in a reducing atmosphere. can do.
[0049]
The exhaust gas purifying catalyst according to the first and second inventions thus obtained can be used effectively without a carrier, but is pulverized into a slurry, coated on a specific monolith carrier, and 400 Used after baking at ~ 900 ° C.
Specifically, as an HC adsorbent layer (inner layer side), a silica sol is added to zeolite powder containing β-zeolite as a main component, and wet pulverized to form a slurry, which is attached to a monolith support, and has a temperature of 400 to 650 ° C. Firing is performed in air and / or under air flow at a temperature in the range.
Next, as a catalyst component layer (middle layer side), Pd-supported powder, alumina powder, and the cerium oxide powder are added to an alumina sol and pulverized in a wet form to form a slurry, which is attached to a monolith support, 400 to 650 Firing is performed in air and / or under air flow at a temperature in the range of ° C.
Next, as an upper catalyst component layer (surface layer side), Rh-supported powder, alumina powder, and the above-mentioned zirconium oxide powder are added to an alumina sol and pulverized wet to form a slurry, which is attached to a monolith support, Firing is performed at a temperature in the range of 650 ° C. in air and / or under air flow.
Pt may be further added to the catalyst component layer and the upper catalyst component layer.
[0050]
The monolith carrier that is a catalyst carrier can be appropriately selected from known catalyst carriers, and examples thereof include a honeycomb monolith carrier made of a refractory material and a metal carrier.
As this honeycomb material, a cordierite material such as ceramic is generally used, but a honeycomb material made of a metal material such as ferritic stainless steel can also be used, and further, the catalyst component powder itself is formed into a honeycomb shape. It may be molded.
The catalyst has a honeycomb shape, and in the present invention, the honeycomb carrier (monolith carrier) has a GSA of 10 cm.²/ Cm³~ 35cm²/ Cm³It is extremely effective for limiting the contact between the HC adsorbent layer and the exhaust gas and delaying the desorption of the adsorbed HC from the HC adsorbent layer.
[0051]
Furthermore, by setting the number of cells of the monolith carrier to 50 to 600 cells per square inch, the contact between the HC adsorbent layer and the exhaust gas is limited, and the desorption of adsorbed HC from the HC adsorbent layer is delayed. It is extremely effective to do.
[0052]
Furthermore, by setting the hydraulic diameter of the monolith carrier to 0.75 mm to 5 mm, the exhaust gas diffusion rate into the HC adsorbent layer is reduced, and the desorption of adsorbed HC from the HC adsorbent layer is delayed. Is extremely effective.
[0053]
The amount of the catalyst component layer attached to the monolith support is preferably 50 g to 600 g per liter of the catalyst in total for the entire catalyst component layer.
The more catalyst component layers having the three-way purification capacity, the better from the viewpoint of catalyst activity and catalyst life, but if the coat thickness of the catalyst component layer becomes too thick, the exhaust gas to the HC adsorbent layer inside the catalyst component layer The diffusion of HC becomes poor, and conversely, the adsorption performance of HC decreases. Further, the larger the HC adsorbent layer, the better from the standpoint of delaying HC desorption, but if the coat thickness of the HC adsorbent layer becomes too thick, the contact between the desorbed HC and the catalyst component layer becomes poor, Conversely, the desorption HC purification activity decreases. For this reason, it is preferable to set the coat weight ratio of the HC adsorbent layer and the catalyst component layer to 5: 1 to 1: 2.
Furthermore, the coat layer thickness in the flat part in the monolith carrier cell, that is, the total thickness of the HC adsorbent layer and the catalyst component layer is preferably 30 μm to 400 μm.
By setting the GSA, the number of cells, and the hydraulic diameter of the monolith carrier carrying the washcoat component within the specified values, a sufficient HC adsorbent layer thickness can be secured to delay the HC desorption, and the desorbed HC The purification performance is improved.
[0054]
Next, an embodiment of the third invention will be described.
In the third aspect of the present invention, Pd, Pd and Pt, or Pd and Rh are provided upstream of the exhaust gas purification catalyst (HC adsorption catalyst) of the first or second aspect described above, that is, upstream of the exhaust passage. And a Pd-supported powder supporting Pd so that the concentration of Pd supported is 4 to 20% by weight, and the amount of Pd supported per liter of catalyst is 100 g / cf (3.5 g / L) to 1000 g / cf. The present invention relates to an exhaust gas purification device in which a Pd-containing catalyst (three-way catalyst) of 35.4 g / L is disposed (see FIG. 3 and the like).
In this exhaust gas purification device, the amount of HC adsorbed by the exhaust gas purification catalyst (HC adsorption catalyst) is 70% or less, preferably 10% to 70% of the amount of HC discharged to a low temperature region immediately after engine start. Is set.
[0055]
When the HC adsorption catalyst of the present invention adsorbs the entire amount of HC in the exhaust gas at a low temperature immediately after the engine is started, when the desorption starts as the temperature of the catalyst component layer rises, the HC adsorption catalyst is disposed above the HC adsorbent layer. Since the catalyst component layer is exposed to an oxygen-deficient state for a long time, the purification performance against desorbed HC is significantly reduced. Therefore, a Pd-containing catalyst that is excellent in HC purification performance in a low temperature region is disposed in front of the HC adsorption catalyst, and the amount of HC adsorbed by the HC adsorption catalyst is reduced to 70% or less of the HC saturated adsorption amount of the HC adsorption catalyst. Setting is preferable in order to maintain and improve the purification performance against desorbed HC of the catalyst component layer disposed on the HC adsorbent layer.
However, if the amount of HC adsorbed by the HC adsorption catalyst exceeds 70% of the HC saturation adsorption amount of the HC adsorption catalyst, the cold HC adsorption efficiency of the HC adsorbent is reduced and desorption is also accelerated. The purification performance of desorbed HC is significantly reduced.
[0056]
In a preferred embodiment of the exhaust gas purifying apparatus according to the third invention, the supported concentration of the Pd-supported powder is 4 to 15% by weight, and the supported amount of palladium of the Pd-containing catalyst is 100 g / cf ( 3.5 g / L) to 500 g / cf (17.7 g / L), and the ignition timing at the time of engine start (first idle) is 40 seconds or less immediately after engine start and 1 from top dead center. The angle is retarded by 30 ° or less.
As a result, the rise in the exhaust temperature is accelerated, the activation of the Pd-containing catalyst arranged in the preceding stage of the HC adsorption catalyst is accelerated, and the HC amount adsorbed by the HC adsorption catalyst is 70% or less of the HC saturated adsorption amount of the HC adsorption catalyst. Set to
[0057]
In another preferred embodiment, the supported concentration of the Pd-supported powder is 4% by weight to 15% by weight and the palladium supported amount of the Pd-containing catalyst is 100 g / cf (3.5 g / L) to 500 g. / Cf (17.7 g / L) or less, air is supplied at an air flow rate of 10 L / min or more for 60 seconds immediately after engine start, and the cold air-fuel ratio immediately after engine start is diluted (A / F = 12-2) 18), the activation of the Pd-containing catalyst is accelerated, and the amount of HC adsorbed by the HC adsorption catalyst is set to 70% or less of the HC saturated adsorption amount of the HC adsorption catalyst.
[0058]
Furthermore, in another preferred embodiment, immediately before the start of HC desorption from the HC adsorption catalyst, the air-fuel ratio is controlled to 14.6 or more, or upstream of the HC adsorption catalyst using means such as an air pump. Alternatively, oxygen and / or air is added to the HC adsorption catalyst.
Before the adsorbed HC starts to desorb from the HC adsorbent or simultaneously with the start of desorption, oxygen and / or air is added upstream of the HC adsorbent catalyst or into the HC adsorbent catalyst, By supplying oxygen to the catalyst component layer, the purification performance of desorbed HC is improved.
[0059]
Furthermore, in another preferred embodiment, in order to improve the purification efficiency of HC desorbed from the HC adsorption catalyst, the detected value of the temperature detector installed in the front part (near the inlet) of the HC adsorption catalyst is equal to or higher than a predetermined temperature. At the rear of the HC adsorption catalyst (near the outlet), so that the A / F detector is 14.6 or more upstream of the HC adsorption catalyst or in the HC adsorption catalyst. Add air (see Figure 3).
[0060]
If the detected value of the temperature detector installed in the vicinity of the inlet of the HC adsorption catalyst is less than a predetermined temperature, for example, 110 ° C., the activation of the catalyst component layer of the HC adsorption catalyst is insufficient, so that oxygen and / or air is added. Conversely, the purification performance of desorbed HC is reduced.
Furthermore, it is preferable to add oxygen and / or air added upstream of the HC adsorption catalyst so that the A / F detector installed near the outlet of the HC adsorption catalyst has a value of 14.6 or more. When A / F is less than 14.6, the effect of improving the purification performance of the catalyst component layer of the HC adsorption catalyst is not sufficient.
[0061]
Furthermore, in order to improve the purification efficiency of HC desorbed from the HC adsorption catalyst, when the detection value of the temperature detector inserted in the catalyst component layer of the HC adsorption catalyst becomes a predetermined temperature or higher, Oxygen and / or air is added upstream of the HC adsorption catalyst or into the HC adsorption catalyst so that the A / F detector installed near the outlet becomes 14.6 or more (see FIG. 4).
If the detected value of the temperature detector inserted in the catalyst component layer of the HC adsorption catalyst is less than the predetermined temperature, the activation of the three-way catalyst layer of the HC adsorption catalyst is insufficient, so oxygen and / or air are added. Conversely, the purification performance of desorbed HC is reduced.
Furthermore, it is preferable to add oxygen and / or air added upstream of the HC adsorption catalyst so that the A / F detector installed near the outlet of the HC adsorption catalyst has a value of 14.6 or more. When A / F is less than 14.6, the effect of improving the purification performance of the catalyst component layer of the HC adsorption catalyst is not sufficient.
[0062]
Furthermore, in order to improve the purification efficiency of HC desorbed from the HC adsorption catalyst, when HC desorption is detected from the detection values of the A / F detectors installed near the inlet and the outlet, Add oxygen and / or air upstream of the HC adsorption catalyst or into the HC adsorption catalyst so that the A / F detector A / F arranged near the outlet is 14.6 or more (see FIG. 4). .
[0063]
In order to minimize the amount of oxygen and / or air added upstream of the HC adsorption catalyst and significantly promote the activation of the catalyst component layer of the HC adsorption catalyst, A installed in the vicinity of the inlet and the outlet of the HC adsorption catalyst When the HC desorption is detected from the difference in the detection value of the / F detector, it is preferable to add so that the A / F detector installed near the outlet of the HC adsorption catalyst becomes 14.6 or more. If A / F is less than 14.6, the purification performance of the catalyst component layer of the HC adsorption catalyst is not sufficiently improved.
[0064]
Further, in a preferred embodiment of the third invention, in the exhaust gas purification apparatus in which the Pd-containing catalyst is arranged in the preceding stage of the HC adsorption catalyst, the unpurified components (HC, CO, NOx) in the Pd-containing catalyst are efficiently used. In order to purify well, it is preferable that the Pd-containing catalyst contains Rh, and the amount of Rh is made smaller than the amount of rhodium contained in the HC adsorption catalyst arranged on the downstream side.
By making the amount of Rh contained in the Pd-containing catalyst smaller than the amount of Rh contained in the HC adsorption catalyst arranged on the downstream side, unpurified components (HC, CO, NOx) in the hot region can be efficiently purified, The purification performance of low-concentration exhaust gas components that could not be purified by the Pd-containing catalyst is improved.
[0065]
The weight ratio of the Rh amount contained in the Pd-containing catalyst and the Rh amount contained in the HC adsorption catalyst disposed on the downstream side is preferably equal (1/1) or less. When the weight ratio of Rh is equal to or greater than that, the purification performance of the low-concentration exhaust gas component is not sufficiently exhibited.
[0066]
Furthermore, another preferred embodiment of the third invention will be described.
In this embodiment, in order to improve the purification efficiency of HC desorbed from the HC adsorption catalyst, a Pd-containing catalyst is disposed upstream of the exhaust gas, and two or more HC adsorption catalysts are disposed downstream thereof (the first invention or the first invention). And an HC adsorption catalyst according to the second aspect of the invention and another HC adsorption catalyst having properties equivalent to those of the HC adsorption catalyst.
By arranging two or more HC adsorption catalysts, low-temperature HC discharged immediately after engine startup is dispersed and adsorbed, reducing the time that the catalyst component layer placed on the HC adsorbent is exposed to an oxygen-deficient state. And the purification performance against desorbed HC is remarkably improved.
[0067]
In still another preferred embodiment, a Pd-containing catalyst is arranged upstream of the exhaust gas, and two or more HC adsorption catalysts are arranged downstream thereof, and the plurality of HC adsorption catalysts are located at positions at different distances from the engine. Is an exhaust gas purification device provided with a different temperature rising rate of each HC adsorption catalyst.
Since the temperature increase rate of the plurality of HC adsorption catalysts is different, the unpurified desorbed HC of the preceding HC adsorption catalyst is re-adsorbed by the subsequent HC adsorption catalyst, and the purification performance for the desorbed HC is remarkably improved.
[0068]
FIG. 12 shows a flow sheet showing a procedure for setting the lean time in the implementation of the exhaust gas purifying apparatus of the present invention. The leaning time was determined according to this flow. In the sheet, S1 to S18 have the following meanings.
[0069]
This flow is executed every predetermined time.
S1 It is determined whether the engine is starting.
For example, when this flow is executed last time, the starter SW is ON, and when it is OFF this time, it is determined that the engine is starting, and initial settings of S2 to S5 are performed.
S2 The temperature of the HC adsorption catalyst (inlet temperature or catalyst component layer temperature) is detected.
For simplicity, the engine coolant temperature may be substituted.
S3 The adsorption capacity of the HC adsorption catalyst is estimated based on the catalyst temperature obtained in S2.
S4 Estimate the time (delay time from the start) when HC desorption starts from the HC adsorption catalyst based on the adsorption capacity obtained in S2.
S5 Estimate the time required from the start of desorption of HC to the completion based on the adsorption capacity obtained in S2.
S6 Measure the elapsed time from the start of the engine.
S7: It is determined whether it is time to desorb HC from the HC adsorption catalyst.
Here, the determination is made by comparing the HC desorption start estimated in S4 with the elapsed time from the start. However, as another method, the detection or estimation of the catalyst temperature is continued even after the engine is started. The determination may be made by comparing the catalyst temperature with the desorption temperature.
S8: It is determined whether the elapsed time after the start is less than a predetermined time (for example, 60 seconds).
S9 If the determination in S8 is YES, the air-fuel ratio is set to lean.
When the air-fuel ratio is made lean about 10% from the stoichiometric air-fuel ratio, the catalyst activation start temperature is lowered, and the catalyst can be activated early.
S10 If the determination in S8 is NO, the air-fuel ratio is set to stoichiometric.
(The lean air-fuel ratio operation has the demerit of increasing the amount of NOx generated, so it is minimized.)
S11: It is determined whether the elapsed time after the start is less than a predetermined time (for example, 40 seconds).
S12 If the determination in S11 is YES, the ignition timing is set to a timing retarded from the normal ignition timing.
By retarding the ignition timing, the exhaust gas temperature can be raised, and unburned HC can be supplied to the catalyst to achieve early activation of the catalyst.
S13 If the determination in S11 is NO, the ignition timing is set to a normal ignition timing. (The ignition timing delay decreases the generated torque (= fuel consumption worsens).
There are also disadvantages, so the minimum is necessary. )
S14 The elapsed time from the start of HC desorption is measured.
S15: Determine whether the HC is being desorbed.
S16: It is determined whether the output of the air-fuel ratio sensor disposed downstream of the catalyst is less than a predetermined value, that is, whether the output exceeds a predetermined lean air-fuel ratio.
If it is determined in S15 that HC is being desorbed, basically the lean air-fuel ratio control is executed in the next S17, but if the catalyst downstream air-fuel ratio sensor indicates a predetermined lean air-fuel ratio or higher, normal control is performed.
S17 If YES in S15, the air-fuel ratio is set to lean.
During HC desorption, the catalyst becomes rich and the HC oxidation efficiency decreases, so the air-fuel ratio is made lean to prevent a decrease in efficiency.
In accordance with the HC desorption characteristics, the lean air-fuel ratio may be set to such an extent that oxygen corresponding to the amount of HC desorbed is supplied.
S18 If NO in S15 (= after HC desorption is completed), normal control is performed.
[0070]
【Example】
The invention is illustrated by the following examples and comparative examples.
Example 1
511 g of β-zeolite powder (H type, Si / 2Al = 75), 57 g of MFI (ZSM5) powder, 1215 g of silica sol (solid content 20%), and 1800 g of pure water are put into a magnetic ball mill, mixed and ground to obtain a slurry liquid. It was. This slurry solution was used as a cordierite monolith carrier (300 cell / 6 mil, GSA 24.1 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.3 mm), excess slurry in the cell was removed with an air stream, dried, and fired at 400 ° C. for 1 hour. The coating operation was repeated until the coating amount at this time was 100 g / L after firing to obtain catalyst-a.
[0071]
Ce3 mol% (CeO₂The alumina powder containing 9.5% by weight in terms of) is impregnated with a dinitrodiamine palladium aqueous solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then at 400 ° C. for 1 hour, and then at 600 ° C. Calcination was performed for 1 hour to obtain Pd-supported alumina powder (powder a). This powder a had a Pd concentration of 6.23% by weight. The powder a may contain lanthanum, zirconium, neodymium and the like.
[0072]
La1 mol% (La₂O₃In terms of 1 wt%) and Zr32 mol% (ZrO)₂The cerium oxide powder containing 25 wt% in terms of) is impregnated with a dinitrodiamine palladium aqueous solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then at 400 ° C. for 1 hour, then at 600 ° C. Calcination for a period of time gave Pd-supported cerium oxide powder (powder b). The Pd concentration of this powder b was 2.0% by weight.
[0073]
562 g of the above Pd-supported alumina powder (powder a), 288 g of Pd-supported cerium oxide powder (powder b), 950 g of nitric acid acidic alumina sol (a sol obtained by adding 10 wt% nitric acid to 10 wt% boehmite alumina) and 1000 g of pure water was put into a magnetic ball mill, mixed and ground to obtain a slurry liquid. The slurry liquid was adhered to the coat catalyst-a, excess slurry in the cell was removed with an air stream, dried, fired at 400 ° C. for 1 hour, a coat layer weight of 60 g / L was applied, and catalyst-b Got.
[0074]
An alumina powder containing 3% by weight of Zr is impregnated with an aqueous rhodium nitrate solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then calcined at 400 ° C. for 1 hour, then at 600 ° C. for 1 hour, and Rh supported alumina A powder (powder c) was obtained. The Rh concentration of this powder c was 1.25% by weight.
[0075]
366 g of Rh-supported alumina powder (powder c), La 1 mol% (La₂O₃1.2% by weight) and Ce20 mol% (CeO)₂25.8 wt%) zirconium oxide powder 300 g and nitric acid acidic alumina sol 1135 g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry liquid. The slurry was adhered to the coated catalyst-b, the excess slurry in the cell was removed by air flow, dried, calcined at 400 ° C. for 1 hour, coated with a coat layer weight of 40 g / L to obtain a catalyst. It was. The cerium oxide powder and alumina powder may contain lanthanum, neodymium and the like.
Next, a barium acetate solution was attached to the catalyst component-supported cordierite monolith support, and then calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO. Thereby, an exhaust gas purifying catalyst (HC adsorption catalyst) of this example was obtained.
[0076]
Example 2
Exhaust gas purification in the same manner as in Example 1 except that 313 g of β-zeolite powder (H type, Si / 2Al = 75), 255 g of MFI (ZSM5) powder, and 1215 g of silica sol (solid content 20%) were used as zeolite. A catalyst was obtained.
[0077]
Example 3
Except for using 454 g of β-zeolite powder (H type, Si / 2Al = 75), 57 g of MFI (ZSM5) powder, 57 g of USY powder, and 1215 g of silica sol (solid content 20%) as zeolite, the same as in Example 1. Thus, an exhaust gas purification catalyst was obtained.
[0078]
Example 4
Except for using 454 g of β-zeolite powder (H type, Si / 2Al = 75), 57 g of MFI (ZSM5) powder, 57 g of AlPO4 powder, and 1215 g of silica sol (solid content 20%) as zeolite, the same as in Example 1. Thus, an exhaust gas purification catalyst was obtained.
[0079]
Example 5
Except for using 454 g of β-zeolite powder (H type, Si / 2Al = 75), 57 g of MFI (ZSM5) powder, 57 g of SAPO4 powder, and 1215 g of silica sol (solid content 20%) as zeolite, the same as in Example 1. Thus, an exhaust gas purification catalyst was obtained.
[0080]
Example 6
Except for using 454 g of β-zeolite powder (H type, Si / 2Al = 75), 57 g of MFI (ZSM5) powder, 57 g of mordenite powder and 1215 g of silica sol (solid content 20%) as zeolite, the same as in Example 1. Thus, an exhaust gas purification catalyst was obtained.
[0081]
Example 7
As zeolite, β-zeolite powder (H type, Si / 2Al = 75) 454 g, MFI (ZSM5) powder 57 g, ferrierite powder 23.5 g, A type zeolite powder 23.5 g, silica sol (solid content 20%) 1215 g Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that it was used.
[0082]
Example 8
The MFI (ZSM5) powder was impregnated and supported with Pd, dried at 150 ° C. for 24 hours, and then calcined at 450 ° C. for 1 hour to obtain a Pd-supported MFI powder (Pd concentration 2.0 wt%). Instead of MFI powder, Pd-supported MFI powder was used and a cordierite monolith carrier (200 cell / 10 mil, GSA 19.0 cm)²/ Cm³Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the hydraulic diameter was 1.53 mm.
[0083]
Example 9
MFI (ZSM5) powder was impregnated with P, dried at 150 ° C. for 24 hours, and then calcined at 450 ° C. for 1 hour to obtain a P-supported MFI powder (Pd concentration 0.4 wt%). Exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that P-supported MFI powder was used instead of MFI powder and the same monolith support as in Example 8 was used.
[0084]
Example 10
The MFI (ZSM5) powder was impregnated with Ca, dried at 150 ° C. for 24 hours, and then calcined at 450 ° C. for 1 hour to obtain a Ca-supported MFI powder (Ca concentration of 0.2% by weight). An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that Ca-supported MFI powder was used instead of MFI powder, and the same monolith support as in Example 8 was used.
[0085]
Example 11
The MFI (ZSM5) powder was impregnated with Mg and supported, dried at 150 ° C. for 24 hours, and then fired at 450 ° C. for 1 hour to obtain an Mg-supported MFI powder (Mg concentration 0.4 wt%). Exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that Mg-supported MFI powder was used instead of MFI powder and the same monolith support as in Example 8 was used.
[0086]
Example 12
The MFI (ZSM5) powder was impregnated with La, dried at 150 ° C. for 24 hours, and then fired at 450 ° C. for 1 hour to obtain an La-supported MFI powder (La concentration 0.4 wt%). An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that La-supported MFI powder was used instead of MFI powder and the same monolith carrier as in Example 8 was used.
[0087]
Example 13
MFI (ZSM5) powder was impregnated with B (boron), dried at 150 ° C. for 24 hours, and then calcined at 450 ° C. for 1 hour to obtain a B-supported MFI powder (B concentration: 0.4 wt%). An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that B-supported MFI powder was used instead of MFI powder, and the same monolith support as in Example 8 was used.
[0088]
Example 14
P-Ca-Zr-La-supported MFI powder in which MFI (ZSM5) powder is successively impregnated with P, Ca, Zr, and La, dried, and fired (each metal concentration 0.1 wt%, total metal concentration 0.4 % By weight). Exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that P-Ca-Zr-La-supported MFI powder was used instead of MFI powder, and the same monolith support as in Example 8 was used.
[0089]
Example 15
P-Mg-Zr-Ce-supported MFI powder in which P, Mg, Zr, and Ce are successively impregnated into MFI (ZSM5) powder, dried, and fired (each metal concentration 0.1 wt%, total metal concentration 0.4 % By weight). An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that PFI—Mg—Zr—Ce-supported MFI powder was used instead of MFI powder, and the same monolith support as in Example 8 was used.
[0090]
Example 16
B-Ca-La-Nd-supported MFI powder in which MFI (ZSM5) powder is successively impregnated with B, Ca, La, and Nd, dried, and fired (each metal concentration 0.1 wt%, total metal concentration 0.4 % By weight). An exhaust gas purifying catalyst was obtained in the same manner as in Example 1, except that B-Ca-La-Nd-supported MFI powder was used instead of the MFI powder, and the same monolith support as in Example 8 was used.
[0091]
Example 17
An alumina powder containing 3% by weight of Zr is impregnated with an aqueous rhodium nitrate solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then calcined at 400 ° C. for 1 hour, then at 600 ° C. for 1 hour, and Rh supported alumina A powder (powder c) was obtained. The Rh concentration of this powder c was 1.25% by weight.
La1 mol% (La₂O₃In terms of 1.2% by weight) and Ce20 mol% (CeO)₂25.8% by weight in terms of zirconium oxide powder was impregnated with a dinitrodiamine platinum aqueous solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then at 400 ° C. for 1 hour, and then at 600 ° C. Was fired for 1 hour to obtain a Pt-supported zirconium oxide powder (powder d). The Pt concentration of this powder d was 1.53% by weight. The above Rh-carrying alumina powder c366g, Pt-carrying zirconium oxide powder (powder d) 300g, and nitric acid acidic alumina sol 1135g were put into a magnetic ball mill, mixed and ground to obtain a slurry liquid. Exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that this slurry was applied to the above coated catalyst-b (however, the monolith carrier was the same as in Example 8).
[0092]
Example 18
La1 mol% (La₂O₃In terms of 1 wt%) and Zr32 mol% (ZrO)₂The cerium oxide powder containing 25 wt% in terms of) is impregnated with a dinitrodiamine platinum aqueous solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then at 400 ° C. for 1 hour, and then at 600 ° C. for 1 hour. Calcination was performed for a time to obtain Pt-supported cerium oxide powder (powder e). The Pt concentration of this powder e was 2.0% by weight.
562 g of the above Pd-supported alumina powder (powder a), 144 g of Pd-supported cerium oxide powder (powder b), 144 g of Pt-supported cerium oxide powder (powder e), 950 g of nitric acid acidic alumina sol (10% by weight to 10% by weight of boehmite alumina) A sol obtained by adding nitric acid) and 1000 g of pure water were put into a magnetic ball mill, mixed and pulverized to obtain a slurry liquid. Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that this slurry was applied to the above-mentioned coated catalyst-a (however, the monolith carrier was the same as in Example 8).
[0093]
Example 19
562 g of the above Pd-supported alumina powder (powder a), 144 g of Pd-supported cerium oxide powder (powder b), 144 g of Pt-supported cerium oxide powder (powder e), 950 g of nitric acid acidic alumina sol (10% by weight to 10% by weight of boehmite alumina) A sol obtained by adding nitric acid) and 1000 g of pure water were put into a magnetic ball mill, mixed and pulverized to obtain a slurry liquid. Catalyst-c was obtained in the same manner as in Example 1 except that this slurry was applied to the above-mentioned coated catalyst-a (provided that the monolith carrier was the same as in Example 8).
366 g of the above Rh-supported alumina powder, La 1 mol% (La₂O₃2% by weight) and Ce20 mol% (CeO)₂25.8 wt%) zirconium oxide powder 300 g, nitric acid acidic alumina sol 1135 g and pure water 1000 g were charged into a magnetic ball mill, mixed and ground to obtain a slurry liquid. Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that this slurry solution was applied to the coat catalyst-c.
[0094]
Example 20
Use potassium acetate solution instead of barium acetate solution and follow the same procedure.₂Exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that 1 g / L was added as O and the same monolith carrier as in Example 8 was used.
[0095]
Example 21
The MFI (ZSM5) powder was impregnated with Ag, dried at 150 ° C. for 24 hours, and then fired at 450 ° C. for 1 hour to obtain an Ag-supported MFI powder (Ag concentration 0.4 wt%). An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that Ag-supported MFI powder was used instead of MFI powder, and the same monolith support as in Example 8 was used.
[0096]
Example 22
As zeolite, 568 g of β-zeolite powder (H type, Si / 2Al = 75) and 1215 g of silica sol (solid content 20%) were used to obtain a zeolite layer coated catalyst-d (however, the monolith support was the same as in Example 8). It was.
357 g of the above Pd-supported alumina powder (powder a), 183 g of Pd-supported cerium oxide powder (powder b), 188 g of Rh-supported alumina powder (powder c), La1 mol% (La₂O₃1.2% by weight) and Ce20 mol% (CeO)₂(25.8 wt% in terms of 1) of zirconium oxide powder, 1185 g of nitric acid acidic alumina sol, and 1000 g of pure water were charged into a magnetic ball mill, and mixed and ground to obtain a slurry liquid. Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that this slurry was applied to the zeolite layer-coated catalyst-d.
[0097]
Example 23
357 g of the above Pd-supported alumina powder (powder a), 183 g of Pd-supported cerium oxide powder (powder b), 188 g of Rh-supported alumina powder (powder c), 154 g of Pt-supported zirconium oxide powder (powder d), 1185 g of acidic alumina sol Pure water was put into a magnetic ball mill, mixed and pulverized to obtain a slurry liquid. An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that this slurry was applied to the zeolite layer-coated catalyst-d (where the monolith support was the same as in Example 8).
[0098]
Reference example 1
La1 mol% (La₂O₃In terms of 1.2% by weight) and Ce20 mol% (CeO)₂25.8% by weight in terms of zirconium oxide powder was impregnated with an aqueous rhodium nitrate solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, then at 400 ° C. for 1 hour, and then at 600 ° C. Calcination was performed for 1 hour to obtain Rh-supported zirconium oxide powder (powder f). The Rh concentration of this powder f was 4.0% by weight.
568 g of β-zeolite powder (H type, Si / 2Al = 75), 353 g of Rh-supported zirconium oxide powder (powder f), 1215 g of silica sol (solid content 20%), and 1800 g of pure water are put into a magnetic ball mill and mixed and pulverized. Thus, a slurry liquid was obtained. This slurry solution was used as a cordierite monolith carrier (300 cell / 6 mil, GSA 24.1 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.1 mm), excess slurry in the cell was removed with an air stream, dried, and fired at 400 ° C. for 1 hour. The coating operation was repeated until the coating amount at this time was 143.5 g / L after firing to obtain catalyst-e.
[0099]
Comparative Example 1
Cordierite monolith support (900 cells / 4 mil, GSA 41.1 cm²/ Cm³Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the hydraulic diameter was 0.74 mm.
[0100]
Comparative Example 2
Exhaust gas purification catalyst was prepared in the same manner as in Example 1 except that the second layer (catalyst component layer = ternary layer) was the Rh layer and the third layer (upper catalyst component layer = ternary layer) was the Pd layer. Obtained.
[0101]
Comparative Example 3
Exhaust gas as in Example 1 except that the total coating layer weight ratio of the first layer (HC adsorbent layer = zeolite layer) and the second and third layers (ternary layer) was 10: 1. A purification catalyst was obtained.
[0102]
Comparative Example 4
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the total coating layer weight ratio of the first layer (zeolite layer) and the second and third ternary layers was 1: 5.
[0103]
Comparative Example 5
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that only A-type zeolite was used as the zeolite species of the first layer.
[0104]
Comparative Example 6
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that only USY was used as the zeolite species of the first layer.
[0105]
Comparative Example 7
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that only MFI was used as the zeolite species of the first layer.
[0106]
Tables 1 and 2 show the specifications of the exhaust gas purifying catalysts obtained in the above Examples, Reference Examples and Comparative Examples.
[0107]
[Table 1]

[0108]
[Table 2]

[0109]
FIG. 1 is a schematic view of a coat layer structure.
[0110]
About each Example, the reference example, and the comparative example, HC purification characteristic evaluation (EC mode, A-bag of LA-4) was performed on the following evaluation conditions using the evaluation system of FIG. The results are shown in Tables 3 and 4.
[0111]
Endurance conditions
Engine displacement 3000cc
Fuel Gasoline (Pb = 12mg / usg, S = 300ppm)
Catalyst inlet gas temperature 650 ° C
Endurance time 100 hours
Performance evaluation conditions
Catalyst capacity (single bank) Three-way catalyst 1.3L + HC adsorption catalyst 2.6L
Evaluation vehicle Nissan Motor Co., Ltd. V type 6 cylinder 3.3L engine
Hydrocarbons (in the gas at the catalyst inlet) that are discharged when the engine is started

[0112]
[Table 3]

[0113]
[Table 4]

[0114]
Compared with the comparative example, the example had higher catalytic activity, and the effects of the present invention described later could be confirmed.
[0115]
Previous catalyst example 1
Cerium 3 mol% (CeO₂8.7% by weight), zirconium 3 mol% (ZrO₂In terms of 6.3 wt%) and lanthanum 2 mol% (La₂O₃Alumina powder (powder A) containing 5.5 wt% in terms of the amount of palladium was impregnated with an aqueous solution of palladium nitrate, dried at 150 ° C. for 12 hours, and then calcined at 400 ° C. for 1 hour. Powder B) was obtained. The Pd concentration of this powder B was 16% by weight.
Lanthanum 1 mol% (La₂O₃In terms of 2% by weight) and 32% by weight of zirconium (ZrO)₂A cerium oxide powder (powder C) containing 25 wt% in terms of the amount of palladium was impregnated with an aqueous palladium nitrate solution, dried at 150 ° C. for 12 hours, and then calcined at 400 ° C. for 1 hour to obtain Pd-supported cerium oxide ( La_0.01Zr_0.32CeO_0.67x) A powder (powder D) was obtained. The Pd concentration of this powder D was 6.0% by weight.
[0116]
The above powder B565g, powder D377g, activated alumina 58.5g, and nitric acid aqueous solution 2000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was used as a cordierite monolith carrier (1.0 L, 600 cell / 4 mil, GSA 34.5 cm).²/ Cm³The slurry was attached to a hydrodynamic diameter of 0.93 mm), excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. This operation was performed twice to obtain a catalyst having a coat weight of 100 g / L-support. The amount of Pd supported was 320.0 g / cf (11.3 g / L) (Catalyst A).
[0117]
Next, a barium acetate solution was attached to the catalyst component-supported cordierite monolith support, and then calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO (catalyst B).
[0118]
Previous catalyst example 2
The above powder B565g, powder D377g, activated alumina 58.5g, and nitric acid aqueous solution 2000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry was adhered to a cordierite monolith support, excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. This operation was performed twice to obtain a catalyst having a coating weight of 91.7 g / L-support. The amount of palladium supported was 293.3 g / cf (10.36 g / L) (Catalyst C).
[0119]
An alumina powder (powder E) containing 3% by weight of Zr was impregnated with an aqueous rhodium nitrate solution, dried at 150 ° C. for 12 hours, and then fired at 400 ° C. for 1 hour to obtain an Rh-supported alumina powder (powder F). The Rh concentration of this powder F was 4.0% by weight.
La 1 mol% Ce 20 mol% Zr 79 mol% zirconium oxide powder (powder G) was impregnated with an aqueous platinum dinitrodiamminate solution, dried at 150 ° C. for 12 hours and then calcined at 400 ° C. for 1 hour to oxidize Pt-supported zirconium A product powder (powder H) was obtained. The Pt concentration of this powder H was 4.0% by weight.
[0120]
The powder F117.5g, powder H117.5g, activated alumina 15g, and nitric acid aqueous solution 1000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry was adhered to a cordierite monolith support (catalyst C) carrying the Pd-containing catalyst component layer, excess slurry in the cell was removed and dried with an air stream, and calcined at 400 ° C. for 1 hour. Coat amount 25 g / L (total coat weight 116.7 g / L) -supported catalyst was obtained. The supported amount of Rh was 13.3 g / cf (0.48 g / L), and the supported amount of Pt was 13.3 g / cf (0.48 g / L) (Catalyst D).
Next, a barium acetate solution was attached to the catalyst component-supported cordierite monolith support (catalyst D), and then calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO (catalyst E).
[0121]
Example 24
800 g of H-type β-zeolite, 1000 g of silica sol (solid content 20%) and 1000 g of pure water were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was used as a cordierite monolith carrier (1.3 L, 200 cells / 10 mil, GSA 19.0 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.53 mm), excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. A catalyst having a coating weight of 200 g / L-carrier was obtained (Catalyst F).
[0122]
La1 mol% Ce20 mol% Zr 79 mol% zirconium oxide powder (powder G) was impregnated with rhodium nitrate aqueous solution, dried at 150 ° C. for 12 hours, and then calcined at 400 ° C. for 1 hour to obtain Rh-supported silconium oxide powder. (Powder I) was obtained. The Rh concentration of this powder I was 8.0% by weight.
500 g of powder B, 80 g of powder D, 353 g of powder I, 47 g of powder A, 20 g of activated alumina and 1000 g of nitric acid aqueous solution were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry was adhered to the catalyst F, excess slurry in the cell was removed by air flow, dried, and calcined at 400 ° C. for 1 hour. This operation was performed twice to obtain catalyst G having a coating weight of 100 g / L (total weight 300 g / L-support). Catalyst G had a palladium loading of 240.0 g / cf (8.48 g / L) and a rhodium loading of 80.0 g / cf (2.83 g / L). Next, after the barium acetate solution was attached to the catalyst G, it was calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO (catalyst H).
[0123]
Example 25
Catalyst I was obtained in the same manner as in Example 24 except that instead of 800 g of H-type β-zeolite, 500 g of H-type β-zeolite, 100 g of ZSM5, 100 g of USY, 50 g of Y-type, and 50 g of mordenite were used.
[0124]
Example 26
Catalyst J was obtained in the same manner as in Example 24 except that 800 g of H-type β-zeolite containing 0.5% by weight of boron and 0.1% by weight of calcium was used instead of 800 g of H-type β-zeolite.
[0125]
Example 27
Instead of 800 g of H-type β-zeolite, 600 g of H-type β-zeolite containing 0.5 wt% phosphorus and 0.1 wt% magnesium, and 100 g of ZSM5 containing 0.5 wt% boron and 0.1 wt% calcium A catalyst K was obtained in the same manner as in Example 24 except that 100 g of USY containing 0.5 wt% phosphorus and 0.1 wt% calcium was used.
[0126]
Example 28
To a solution obtained by dissolving 20 g of ammonium dihydrogen phosphate in 1500 g of pure water, 1000 g of H-type β-zeolite was added, and 25% ammonia water was added dropwise to adjust the pH to 9.0, followed by stirring and mixing for 24 hours. .
Β-Zeolite was collected from this mixed solution by filtration, dried at 120 ° C. for 24 hours, and then calcined in air at 650 ° C. for 2 hours to obtain Powder J. Further, this powder J was impregnated with a palladium nitrate solution to obtain a powder K containing 1 wt% Pd and 0.5 wt% Pd. 800 g of this powder K, 1000 g of silica sol (solid content 20%) and 1000 g of nitric acid aqueous solution were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was used as a cordierite monolith carrier (1.3 L, 200 cells / 10 mil, GSA 19.0 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.53 mm), excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. A catalyst having a coat weight of 200 g / L-carrier was obtained (catalyst L). The amount of Pd supported was 45.3 g / cf (1.6 g / L).
The above-mentioned powder B500g, powder D80g, powder A30g, activated alumina 15g, and nitric acid aqueous solution 1000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry was adhered to the catalyst L, excess slurry in the cell was removed by air flow, dried, and calcined at 400 ° C. for 1 hour. This operation was performed twice to obtain catalyst M.
Further, 353 g of the above powder I, 17 g of powder A, 5 g of activated alumina, and 1000 g of nitric acid aqueous solution were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was adhered to the catalyst M, and excess slurry in the cell was removed and dried with an air stream, and calcined at 400 ° C. for 1 hour. This operation was performed twice to obtain a catalyst N having a coat weight of 100 g / L (total weight 300 g / L-support). Catalyst M had a palladium loading of 285.4 g / cf (10.08 g / L) and a rhodium loading of 80 g / cf (2.83 g / L).
Next, a barium acetate solution was attached to the catalyst component-supported cordierite monolith support (catalyst N) and then calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO (catalyst O).
[0127]
Example 29
H-type β-zeolite containing 0.28% by weight of palladium, 0.2% by weight of phosphorus, 0.3% by weight of boron, 0.1% by weight of magnesium and 0.1% by weight of calcium instead of 800 g of H-type β-zeolite 500 g, 100 g of ZSM5 containing 0.33 wt% Pt and 0.1 wt% calcium, 200 g USY containing 0.28 wt% palladium and 0.2 wt% phosphorus, 0.33 wt% Pt, 0.1 wt% boron 100 g of mordenite containing 0.1% by weight of magnesium and cordierite monolith carrier (200 cell / 10 mil, GSA 19.0 cm)²/ Cm³The catalyst P was obtained in the same manner as in Example 1 except that the hydraulic diameter was 1.53 mm. The coating amount was 200 g / L, the loading amount of Pd was 11.1 g / cf (0.39 g / L), and the loading amount of Pt was 3.7 g / cf (0.13 g / L).
[0128]
30 g of the above powder A, 500 g of powder B, 80 g of powder D, 20 g of activated alumina and 1000 g of nitric acid aqueous solution were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. The slurry was adhered to the catalyst P, excess slurry in the cell was removed by air flow, dried, and calcined at 400 ° C. for 1 hour to obtain catalyst Q.
The powder F176g, powder H117g, powder I177g, activated alumina 30g, and nitric acid aqueous solution 1000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry was adhered to the catalyst Q, excess slurry in the cell was removed and dried with an air stream, and calcined at 400 ° C. for 1 hour. Next, a barium acetate solution was attached to the catalyst component-supported cordierite monolith support, and then calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO (catalyst R). Coat amount 50 g / L (total weight 250 g / L-carrier), Pd loading amount 251.2 g / cf (8.87 g / L), Pt loading amount 16.9 g / cf (0.60 g / L), Rh The supported amount was 40.0 g / cf (1.42 g / L) (catalyst R).
[0129]
Previous stage catalyst example 3
Powder B1324g, powder F106g, powder H27g, activated alumina 43g, and nitric acid aqueous solution 2000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry solution was used as a cordierite monolith carrier (1.0 L, 900 cell / 2 mil, GSA 43.6 cm).²/ Cm³The excess slurry in the cell was removed with an air stream, dried, and fired at 400 ° C. for 1 hour. This operation was performed twice to obtain a catalyst having a coat weight of 150 g / L-support. Next, after the barium acetate solution was attached to the catalyst, it was calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO.
The palladium loading is 600.0 g / cf (21.2 g / L), the platinum loading is 3.0 g / cf (0.11 g / L), and the rhodium loading is 12.0 g / cf (0.42 g / L). (Catalyst S).
[0130]
Example 30
H-type β-zeolite 800 g, powder I 88.3 g, powder E 161.5 g, silica sol 1000 g (solid content 20%) and pure water 1000 g were charged into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was used as a cordierite monolith carrier (1.3 L, 200 cells / 10 mil, GSA 19.0 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.53 mm), excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. A catalyst having a coat weight of 250 g / L-support was obtained (Catalyst T).
[0131]
The powder B500g, the powder D80g, the powder I176.5g, the powder E203g, the powder A40g, the activated alumina 20g, and the nitric acid aqueous solution 1000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. The slurry was adhered to the catalyst T, excess slurry in the cell was removed and dried with an air stream, and calcined at 400 ° C. for 1 hour. This operation was performed twice, the coating weight was 100 g / L (total weight 300 g / L-carrier), the palladium loading was 240.0 g / cf (8.48 g / L), and the rhodium loading was 80.0 g / cf ( 2.83 g / L) of catalyst U was obtained.
Next, after a barium acetate solution was attached to the catalyst U, it was calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO (catalyst V).
[0132]
Comparative Example 8
Cordierite monolith support (1.3 L, 600 cells / 2 mil, GSA 36.2 cm²/ Cm³The catalyst W was obtained in the same manner as in Example 24 except that the hydraulic diameter was 0.97 mm.
[0133]
Comparative Example 9
Cordierite monolith carrier (1.3 L, 900 cell / 4 mil, GSA 41.1 cm²/ Cm³Catalyst X was obtained in the same manner as in Example 24 except that the hydraulic diameter was 0.74 mm.
[0134]
Comparative Example 10
800 g of H-type β-zeolite, 1000 g of silica sol (solid content 20%) and 1000 g of pure water were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was used as a cordierite monolith carrier (1.3 L, 200 cells / 10 mil, GSA 19.0 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.53 mm), excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. Catalyst Y with a coating weight of 20 g / L-carrier was obtained.
A catalyst Z was obtained in the same manner as in Example 24 except that the catalyst Y was used instead of the catalyst F.
[0135]
Comparative Example 11
800 g of H-type β-zeolite, 1000 g of silica sol (solid content 20%) and 1000 g of pure water were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was used as a cordierite monolith carrier (1.3 L, 200 cells / 10 mil, GSA 19.0 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.53 mm), excess slurry in the cell was removed by air flow, dried, and fired at 400 ° C. for 1 hour. A catalyst AA having a coat weight of 300 g / L-support was obtained.
160.0 g of powder J (alumina powder carrying Pd on powder A, Pd concentration 50 wt%), 17 g of powder K (cerium oxide powder carrying Pd on powder C, 28 wt% Pd concentration), powder Ag, powder L (zirconium oxide powder carrying Rh on powder G, Rh concentration 25 wt%) 113.0 g, activated alumina 10 g, and nitric acid aqueous solution 500 g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry liquid was adhered to the catalyst AA, excess slurry in the cell was removed by air flow, dried, and calcined at 400 ° C. for 1 hour. This operation was performed twice. The coating weight was 30 g / L (total weight 330 g / L-carrier), the palladium loading was 240.0 g / cf (8.48 g / L), and the rhodium loading was 80.0 g / cf ( 2.83 g / L) of catalyst BB was obtained.
Next, after a barium acetate solution was attached to the catalyst U, it was calcined at 400 ° C. for 1 hour to obtain a catalyst CC containing 10 g / L as BaO.
[0136]
Comparative Example 12
The above powder B659g, powder D80g, powder I35.3g, powder A206g, activated alumina 20g, and nitric acid aqueous solution 1000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry was adhered to the catalyst F, excess slurry in the cell was removed by air flow, dried, and calcined at 400 ° C. for 1 hour. This operation was performed twice to obtain a catalyst DD having a coat weight of 100 g / L (total weight 300 g / L-support). The catalyst DD had a palladium loading of 312.0 g / cf (11.02 g / L) and a rhodium loading of 8.0 g / cf (0.28 g / L).
Next, after a barium acetate solution was attached to the catalyst DD, it was calcined at 400 ° C. for 1 hour to obtain a catalyst EE containing 10 g / L as BaO.
[0137]
Comparative Example 13
The above-mentioned powder B162g, powder D80g, powder I15g, powder A723g, activated alumina 20g and nitric acid aqueous solution 1000g were put into a magnetic ball mill, mixed and pulverized to obtain a slurry. This slurry solution was used as a cordierite monolith carrier (1.0 L, 900 cell / 2 mil, GSA 43.6 cm).²/ Cm³The excess slurry in the cell was removed with an air stream, dried, and fired at 400 ° C. for 1 hour. This operation was performed twice to obtain a catalyst having a coat weight of 100 g / L. The catalyst DD had a palladium loading of 73.3 g / cf (2.59 g / L) and a rhodium loading of 6.7 g / cf (0.24 g / L).
Next, after a barium acetate solution was attached to the catalyst, it was calcined at 400 ° C. for 1 hour to obtain a catalyst FF containing 10 g / L as BaO.
[0138]
Tables 5 and 6 show the specifications of the exhaust gas purifying catalysts obtained in Examples 24 to 30, the first catalyst examples 1 to 3 and the comparative examples 8 to 13.
[0139]
[Table 5]

[0140]
[Table 6]

[0141]
Test example
The exhaust gas purifying catalysts obtained in Examples 24 to 30, Pre-catalyst Examples 1 to 3 and Comparative Examples 8 to 13 were subjected to durability under the following durability conditions.

[0142]
Using the catalysts of Examples 24 to 30, Durability Catalyst Examples 1 to 3 and Comparative Examples 8 to 13 that were durable under the above conditions, HC purification characteristics evaluation was performed under the following evaluation conditions for Examples 31 to 50 and Comparative Examples 14 to 25 ( EC mode, LA-4 A-bag) was performed using the system (exhaust gas purifier) of FIGS. The results are shown in Tables 7-10.
[0143]
Performance evaluation conditions
Catalyst capacity (single bank) Three-way catalyst 2.0L (1.0L + 1.0L) + HC adsorption catalyst 1.3L-2.6L
Evaluation vehicle Nissan Motor Co., Ltd. V type 6 cylinder 3.3L engine
Hydrocarbons (in the gas at the catalyst inlet) that are discharged when the engine is started

[0144]
[Table 7]

[0145]
[Table 8]

[0146]
[Table 9]

[0147]
[Table 10]

[0148]
Example 55
β-zeolite powder (H type, Si / 2Al = 25) 700 g, Idemitsu ZSM5 (H type, Si / 2Al = 30) powder 200 g, silica sol (solid content 20%) 100 g, pure 1500 g were put into a magnetic ball mill, The mixture was pulverized to obtain a slurry liquid. This slurry solution was used as a cordierite monolith carrier (300 cell / 6 mil, GSA 24.1 cm).²/ Cm³The slurry was attached to a hydraulic diameter of 1.3 mm), excess slurry in the cell was removed with an air stream, dried, and fired at 400 ° C. for 1 hour. The coating operation was repeated until the coating amount at this time was 150 g / L after firing to obtain catalyst-a.
[0149]
Alumina powder containing 3 mol% of Ce was impregnated with a dinitrodiamine palladium aqueous solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, calcined at 400 ° C. for 1 hour, then calcined at 600 ° C. for 1 hour, Pd A supported alumina powder (powder a) was obtained. This powder a had a Pd concentration of 6.23% by weight. The powder a may contain lanthanum, zirconium, neodymium and the like.
[0150]
A cerium oxide powder containing 1 mol% La and 32 mol% Zr is impregnated with a dinitrodiamine palladium aqueous solution or sprayed at high speed with stirring, dried at 150 ° C. for 24 hours, calcined at 400 ° C. for 1 hour, and then at 600 ° C. Calcination was performed for 1 hour to obtain Pd-supported cerium oxide powder (powder b). The Pd concentration of this powder a was 2.0% by weight.
[0151]
562 g of the above Pd-supported alumina powder (powder a), 288 g of Pd-supported cerium oxide powder (powder b), 950 g of nitric acid acidic alumina sol (a sol obtained by adding 10 wt% nitric acid to 10 wt% boehmite alumina) and 1000 g of pure water was put into a magnetic ball mill, mixed and ground to obtain a slurry liquid. The slurry liquid was adhered to the coat catalyst-a, excess slurry in the cell was removed with an air stream, dried, fired at 400 ° C. for 1 hour, a coat layer weight of 60 g / L was applied, and catalyst-b Got.
[0152]
An alumina powder containing 3% by weight of Zr is impregnated with an aqueous rhodium nitrate solution or sprayed with high-speed stirring, dried at 150 ° C. for 24 hours, calcined at 400 ° C. for 1 hour, and then calcined at 600 ° C. for 1 hour. A supported alumina powder (powder c) was obtained. The Rh concentration of this powder c was 1.25% by weight.
[0153]
366 g of the above Rh-supported alumina powder (powder c), 300 g of zirconium oxide powder containing 1 mol% of La and 20 mol% of Ce, and 1135 g of nitric acid acidic alumina sol were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. The slurry was adhered to the coated catalyst-b, the excess slurry in the cell was removed by air flow, dried, calcined at 400 ° C. for 1 hour, coated with a coat layer weight of 40 g / L to obtain a catalyst. It was.
The cerium oxide powder and alumina powder may contain lanthanum, neodymium and the like.
Next, a barium acetate solution was attached to the catalyst component-supported cordierite monolith support, and then calcined at 400 ° C. for 1 hour to contain 10 g / L as BaO.
[0154]
Example 56
Exhaust gas purification catalyst was prepared in the same manner as in Example 1 except that 500 g of β-zeolite powder (H type, Si / 2Al = 25) and Idemitsu ZSM5 (H type, Si / 2Al = 30) powder 400 g were used. Obtained.
[0155]
Example 57
Idemitsu-made ZSM5 (H-type, Si / 2Al = 30) powder is sequentially impregnated with Ag, P, dried and fired to support Ag-P-supported ZSM5 powder (each metal concentration 0.2 wt%, total metal concentration 0. 4 wt.%) And β-zeolite powder (supported by Ag-P) impregnated with β-zeolite (H type, Si / 2Al = 25) by successive impregnation, drying and firing (each metal concentration 0.2 wt.%) Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the total metal concentration was 0.4 wt%.
[0156]
Example 58
Pd-Mg-Ca-La-supported by successive impregnation, drying, and firing of Pd, Mg, Ca, Y, La, Nd, B, and Zr into Idemitsu ZSM5 (H type, Si / 2Al = 30) powder Nd-B-Zr-supported ZSM5 powder (each metal concentration 0.05 wt%, total metal concentration 0.4 wt%), β-zeolite (H type, Si / 2Al = 25), Sr, Ba, Ag, Ce , Nd and P were sequentially impregnated, dried, and fired, except that Mg, Y, Nd and Zr-supported β-zeolite powder (each metal concentration 0.05% by weight, total metal concentration 0.3% by weight) was used. In the same manner as in Example 1, an exhaust gas purification catalyst was obtained.
[0157]
Comparative Example 27
An exhaust gas purification catalyst was obtained in the same manner as in Example 55 except that 900 g of Idemitsu ZSM5 (H type, Si / 2Al = 30) powder was used.
[0158]
Comparative Example 28
Exhaust gas purification catalyst was obtained in the same manner as in Example 59, except that 900 g of β-zeolite powder (H type, Si / 2Al = 25) powder was used.
[0159]
【The invention's effect】
Hereinafter, the effects of the first invention will be described generally.
(1) Optimization of zeolite species
In the HC adsorption catalyst using zeolite, since there is a correlation between the HC species distribution in the exhaust gas and the pore diameter of the zeolite, it is necessary to select a zeolite having an optimum pore diameter. Previously, MFI (ZSM5) was used as the main component and zeolites with other pore sizes (for example, USY) were blended to adjust the pore distribution. -Since the desorption characteristics are different, there is a problem that the adsorption of the exhaust gas HC species is insufficient.
In the present invention, by adopting β-zeolite having two kinds of pore diameters and excellent durability as a main component, there is little distortion due to durability, and the pore distribution can be widely maintained from the initial stage to after the end, Adsorption / desorption characteristics are improved compared to conventional methods. Further, by combining two or more kinds of zeolites, an effect of further widening the distribution of zeolite pore diameters can be obtained.
That is, in the present invention, since mordenite is used as a seed crystal of ZSM5, the depth inside the pore is wider than that of normal ZSM5. When this ZSM5 is used as an HC adsorbing material, the diffusion rate of HC into the pores is slow (if HC with a large molecular diameter comes to the entrance of the pores, the diffusion of other HCs is inhibited, and cold is efficiently performed in a short time. Adsorption performance is inferior because HC cannot be adsorbed). However, once HC diffuses into the pores, it becomes difficult to escape to the outside (desorption is slow). In the present invention, by combining ZSM5 and β-zeolite, an HC adsorbent for automobiles having excellent adsorption / desorption characteristics has been developed.
[0160]
(2) Optimization of ternary precious metal species (catalyst component species)
Conventionally, specifications in which noble metal species such as Rh, Pt, and Pd coexist in the same layer, specifications in which the Rh layer and the Pd layer are separately applied, and the like have been proposed.
In the present invention, a coexistence layer of Pd and Rh is provided on the zeolite layer, or a Pd layer is provided on the zeolite layer, and an Rh layer is provided thereon, and Pt can be added to one or both layers.
By providing a Pd layer with excellent HC low-temperature activity on the zeolite, HC desorbed from the zeolite can be preferentially purified. Rh coexists in the Pd layer, or an Rh layer is provided on the Pd layer. Even if a gas slightly shifted to a rich atmosphere from the air-fuel ratio flows, HC, CO, and NOx can be purified in a well-balanced manner. Furthermore, the addition of Pt can improve the poisoning resistance.
[0161]
(3) Optimization of coat layer structure of zeolite layer + ternary precious metal layer
Conventionally, the ratio of the coating layer between the zeolite layer (HC adsorbing material layer) and the ternary layer (catalyst component layer) and the GSA of the monolith support carrying the coating layer have not been particularly presented. If the structure of the layer and the ternary layer is not optimal, there is a problem that the cycle of HC adsorption / desorption / purification cannot be performed effectively.
In the present invention, the coating layer ratio of the zeolite layer and the ternary layer is set to a ratio of 9: 1 to 1: 4 by weight, and further, the monolithic carrier GSA provided with the coating layer is 10 cm.²/ Cm³~ 35cm²/ Cm³By defining in this range, the HC adsorption / desorption / purification has a good balance. That is, if the proportion of the ternary layer is too large with respect to the zeolite layer, gas diffusion to the zeolite layer disposed in the lower layer is deteriorated, and sufficient adsorption performance commensurate with the amount of zeolite cannot be obtained. On the other hand, when the proportion of the ternary layer is small, the oxidation performance of the desorbed HC and the exhaust gas purification performance cannot be sufficiently obtained. Moreover, if GSA becomes too large, the HC holding power of the zeolite layer becomes small, and sufficient purification performance cannot be obtained with the ternary layer disposed on the upper part. Also, if GSA is small, exhaust gas purification performance cannot be obtained sufficiently.
[0162]
The exhaust gas purifying catalyst according to claim 1 can perform the purification performance of HC, CO, and NOx in a well-balanced manner. Furthermore, in addition to the above effects, the HC purifying performance can be improved by controlling the diffusivity (speed) of the exhaust gas that passes through the monolith carrier cell and diffuses into the coat layer. Furthermore, HC desorption can be delayed to improve the HC purification performance.
[0163]
In addition to the above effects, the exhaust gas purification catalyst according to claim 4 can further delay the desorption of HC and improve the hydrocarbon purification performance.
[0164]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 5 can further delay the desorption of HC and improve the hydrocarbon purification performance.
[0165]
The exhaust gas purifying catalyst according to claim 6 can perform the purification performance of HC, CO, and NOx in a well-balanced manner. Furthermore, in addition to the above effects, the HC purifying performance can be improved by controlling the diffusivity (speed) of the exhaust gas that passes through the monolith carrier cell and diffuses into the coat layer.
[0166]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 7 can further improve the HC purification performance.
[0167]
The exhaust gas purifying catalyst according to claim 8 can further improve the HC purification performance in addition to the above effects.
Furthermore, since an alkali metal or alkaline earth metal is contained, the effect of further improving the low-temperature activity and the purification performance is exhibited in order to suppress sintering of the noble metal.
[0168]
The exhaust gas purifying catalyst according to claim 9 can effectively adsorb various types of HC in addition to the above effects.
[0169]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 10 has a wide range of HC species that can be adsorbed, and can effectively adsorb more types of HC.
[0170]
In addition to the above effects, the exhaust gas purifying device according to claim 11 combines various HC adsorbents having different pore diameters to adsorb HC species discharged at a low temperature immediately after starting the engine with high efficiency. Adsorption ability can be improved.
[0171]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 12 can further improve the adsorption characteristics and desorption suppression ability.
[0172]
The exhaust gas purifying catalyst according to claim 13 adsorbs HC species discharged at a low temperature immediately after engine startup with high efficiency, and further, since the structural change and performance deterioration after durability are small, the desorption rate is delayed. Can be achieved.
[0173]
The exhaust gas purifying catalyst according to claim 14 can further improve the poisoning resistance in addition to the above effects.
[0174]
In addition to the above effects, the exhaust gas purification catalyst according to claim 15 can further improve the HC purification performance.
[0175]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 16 can suppress a decrease in catalyst performance due to a change in chemical state of rhodium after durability.
[0176]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 17 can suppress a decrease in catalyst performance due to reduction of the catalyst component.
[0177]
In addition to the above effects, the exhaust gas purifying catalyst according to claim 18 can suppress the structural stability after durability and the deterioration of the catalyst performance due to the change in the chemical state of palladium.
[0178]
The exhaust gas purifying device according to claim 19 is a combination of a Pd-containing catalyst having excellent low-temperature activity and the HC adsorption catalyst of the present invention, and the amount of HC adsorbed by the HC adsorption catalyst By setting it to 10% to 70%, the purification performance of desorbed HC can be improved.
[0179]
The exhaust gas purifying device according to claim 20 is a combination of a Pd-containing catalyst excellent in low-temperature activity and an HC adsorption catalyst, and the amount of HC adsorbed by the HC adsorption catalyst is 30% to the amount of HC discharged at a low temperature immediately after engine start By setting it to 70% and further combining means for promoting early activation of the following exhaust gas purification catalyst, the amount of HC adsorbed by the HC adsorption catalyst can be further reduced, and the desorption HC purification performance can be improved.
[0180]
The exhaust gas purifying apparatus according to claim 21 is the exhaust gas purifying apparatus according to claim 22, wherein the Pd-containing catalyst (three-way catalyst) disposed in front of the HC adsorption catalyst can be activated at an early stage. The purification performance of HC from which the catalyst is desorbed can be improved.
[0181]
The exhaust gas purifying device according to claim 22 is the exhaust gas purifying device according to claim 22, wherein the Pd-containing catalyst (three-way catalyst) arranged in the preceding stage of the HC adsorption catalyst can be activated early, and the HC adsorption The purification performance of HC from which the catalyst is desorbed can be improved.
[0182]
The exhaust gas purifying apparatus according to claim 23 can achieve early activation of the Pd-containing catalyst (three-way catalyst) disposed upstream of the HC adsorption catalyst and improvement of the purification performance. Can be improved.
[0183]
In addition to the above effects, the exhaust gas purifying apparatus according to the twenty-fourth aspect can suppress the temperature drop of the catalyst component layer and can efficiently purify the desorbed HC.
[0184]
In addition to the above effects, the exhaust gas purifying device according to claim 25 can suppress the temperature drop of the catalyst component layer and can efficiently purify the desorbed HC.
[0185]
In addition to the above effects, the exhaust gas purification device according to the twenty-sixth aspect can further suppress the temperature drop of the catalyst component layer and improve the purification performance, and can efficiently desorb the desorbed HC.
[0186]
In addition to the above effects, the exhaust gas purifying device according to claim 27 can efficiently purify unpurified low-concentration exhaust gas components (HC, CO, NOx) with the pre-stage Pd-containing catalyst.
[0187]
In addition to the above effects, the exhaust gas purifying device according to the twenty-eighth aspect can further improve the adsorption / desorption / purification performance of HC, and can efficiently desorb the desorbed HC.
[0188]
In addition to the above effects, the exhaust gas purifying device according to the twenty-ninth aspect can further efficiently purify the desorbed HC.
[Brief description of the drawings]
FIG. 1A is a perspective view showing a washcoat layer structure of a catalyst of the present invention. (B) is the partial expansion part of (a).
FIG. 2 is a system (evaluation system 1) diagram showing an exhaust system of an engine used for evaluating a catalyst of the present invention.
FIG. 3 is a system (evaluation system 2) diagram showing an exhaust system of an engine used for evaluating the catalyst of the present invention.
FIG. 4 is a system (evaluation system 3) diagram showing an exhaust system of an engine used for evaluating the catalyst of the present invention.
FIG. 5 is a system (evaluation system 4) diagram showing an exhaust system of an engine used for evaluating the catalyst of the present invention.
FIG. 6 is a system (evaluation system 5) diagram showing an exhaust system of an engine used for evaluating a catalyst of the present invention.
FIG. 7 is a system (evaluation system 6) diagram showing an exhaust system of an engine used for evaluating the catalyst of the present invention.
FIG. 8 is a system (evaluation system 7) diagram showing an exhaust system of an engine used for evaluating a catalyst of the present invention.
FIG. 9 is a graph (map) showing the relationship between the amount of precious metal (PM) for each engine type and the remaining rate of engine outmission.
FIG. 10 is a flow sheet for creating a noble metal selection map for a three-way catalyst.
FIG. 11 is a graph showing the relationship between engine out-emission remaining rate and time.
FIG. 12 is a flowchart for calculating a lean time.
[Explanation of symbols]
1 Hydrocarbon adsorption layer (HC adsorbent layer)
2 Three-way catalyst layer (catalyst component layer)
3 Gas passage
4 Three-way catalyst
5 HC adsorption catalyst

Claims (27)

GSA is on the monolithic support of ^{10cm 2 / cm 3 ~35cm 2 /} cm 3, HC adsorbent layer and the exhaust gas purifying catalyst of the catalyst component layer formed by coating in this order containing a catalyst component comprising a hydrocarbon adsorbent Because
The hydrocarbon adsorbent of the HC adsorbent layer is mainly composed of zeolite,
Containing Mutotomoni of the catalyst component layer of palladium (Pd), platinum (Pt) and at least one noble metal selected from the group consisting of rhodium (Rh) as catalyst components,
In the catalyst component layer, a cerium oxide containing 1 to 40 mol% in terms of metal and 60 to 98 mol% of Ce selected from the group consisting of Zr, Nd and La, and Pd are contained,
The weight ratio of the HC adsorbent layer to the catalyst component layer is 9: 1 to 1: 4;
An exhaust gas purifying catalyst, wherein the coating layer thickness is 30 μm to 400 μm, which is the sum of the thicknesses of the HC adsorbent layer and the catalyst component layer in the flat portion in the cell of the monolith carrier. GSA is on the monolithic support of ^{10cm 2 / cm 3 ~35cm 2 /} cm 3, HC adsorbent layer and the exhaust gas purifying catalyst of the catalyst component layer formed by coating in this order containing a catalyst component comprising a hydrocarbon adsorbent Because
The hydrocarbon adsorbent of the HC adsorbent layer is mainly composed of zeolite ,
In the HC adsorbent layer, zirconium oxide containing 1 to 40 mol% in terms of metal of at least one selected from the group consisting of Ce, Nd and La, and Rh are contained,
The catalyst component layer includes at least one noble metal selected from the group consisting of palladium (Pd), platinum (Pt) and rhodium (Rh) as a catalyst component;
The weight ratio of the HC adsorbent layer to the catalyst component layer is 9: 1 to 1: 4;
An exhaust gas purifying catalyst, wherein the coating layer thickness is 30 μm to 400 μm, which is the sum of the thicknesses of the HC adsorbent layer and the catalyst component layer in the flat portion in the cell of the monolith carrier. The coating layer thickness of 30 μm to 400 μm, which is the sum of the thicknesses of the HC adsorbent layer and the catalyst component layer in the flat portion in the cell of the monolithic carrier, is according to claim 1 or 2 . Exhaust gas purification catalyst.   The exhaust gas purification catalyst according to any one of claims 1 to 3, wherein the number of cells per square inch of the monolith support is 50 to 600.   The exhaust gas purification catalyst according to any one of claims 1 to 4, wherein the monolithic carrier has a hydraulic diameter of 0.75 mm to 5 mm. The exhaust gas purifying catalyst according to any one of claims 1 to 5 , wherein the zeolite is β-zeolite. The exhaust gas purification catalyst according to claim 6 , wherein a weight ratio of the HC adsorbent layer and the catalyst component layer is 5: 1 to 1: 2.   The zeolite is β-zeolite, the catalyst component layer contains Pd and Rh, the weight ratio of the HC adsorbent layer and the catalyst component layer is 5: 1 to 1: 2, The exhaust gas purifying catalyst according to any one of claims 1 to 5, wherein / or alkaline earth metal is contained in the HC adsorbent layer and / or the catalyst component layer.   The exhaust gas purification catalyst according to any one of claims 6 to 8, wherein the β-zeolite is H-type β-zeolite having a Si / 2Al ratio of 10 to 500. The HC adsorbent layer further contains at least one selected from the group consisting of MFI zeolite, Y-type zeolite, USY zeolite, A-type zeolite, X-type zeolite, mordenite, ferrierite, AlPO ₄ and SAPO. The exhaust gas purifying catalyst according to claim 9.   11. The exhaust gas purifying apparatus according to claim 10, wherein the HC adsorbent layer contains 5 to 45% by weight of at least one selected from the group consisting of MFI zeolite, Y-type zeolite, USY zeolite, and mordenite. catalyst.   The zeolite of the HC adsorbent layer contains at least one selected from the group consisting of Pd, Mg, Ca, Sr, Ba, Ag, Y, La, Ce, Nd, P, B, and Zr. The exhaust gas purifying catalyst according to any one of claims 1 to 11.   The exhaust according to any one of claims 1 to 12, wherein the hydrocarbon adsorbent contains at least one selected from the group consisting of Pt, Pd, P, B, Mg, and Ca. Gas catalyst.   9. The exhaust gas purifying catalyst according to claim 8, wherein Pt further coexists in the catalyst component layer. In the catalyst component layer, further, Ce, of claims 1 to 14 in which at least one selected from the group consisting of Zr and La, characterized in that zirconium oxide containing 1 to 40 mol% in terms of metal is contained The exhaust gas purifying catalyst according to any one of the items. In the catalyst component layer, alumina containing at least one selected from the group consisting of Ce, Zr and La in terms of metal in an amount of 1 to 10 mol%,
The exhaust according to any one of 1 to 15 , further comprising a cerium oxide containing 1 to 40 mol% of a metal selected from the group consisting of Zr, Nd and La in terms of metal. Gas purification catalyst. A Pd-supported powder containing Pd, Pd and Pt, or Pd and Rh and having a Pd-supporting concentration of 4 to 20% by weight before the exhaust gas purifying catalyst according to any one of claims 1 to 16. Containing a Pd-containing catalyst having a Pd loading per liter of catalyst of 100 g / cf (3.5 g / L) to 1000 g / cf (35.4 g / L),
An exhaust gas purification apparatus, wherein the amount of hydrocarbon adsorbed by the exhaust gas purification catalyst is set to 70% or less of the saturated hydrocarbon adsorption amount of the exhaust gas purification catalyst. The Pd-supported powder has a Pd-supporting concentration of 4 to 15% by weight, and the Pd-containing catalyst has a Pd-supporting amount of 100 g / cf (3.5 g / L) to 500 g / cf (17.7 g / L). The exhaust gas purification device according to claim 17 . Installed in an automobile engine, the ignition timing at the time of engine start (first idle) is retarded by 1 ° to 30 ° from top dead center for a period of 40 seconds or less immediately after engine start, thereby speeding up the exhaust temperature rise. ,
The exhaust gas purification device according to claim 17 or 18 , wherein the activation of the Pd-containing catalyst is accelerated. It is mounted on an automobile engine, and air is supplied at an air flow rate of 10 L / min or more for 60 seconds immediately after the engine is started, and the cold air-fuel ratio immediately after the engine is started is diluted to A / F = 12 to 18, thereby reducing the Pd The exhaust gas purification device according to claim 17 or 18 , wherein the activation of the contained catalyst is accelerated. Immediately before the start of desorption of hydrocarbons from the exhaust gas purification catalyst, oxygen and / or air is added upstream of the exhaust gas purification catalyst or into the exhaust gas purification catalyst. The exhaust gas purification device according to any one of claims 17 to 20 . A temperature detector is added in the vicinity of the inlet of the exhaust gas purification catalyst, and an A / F detector is added in the vicinity of the outlet. When the detected value of the temperature detector becomes 110 ° C. or higher, the A / F detector is 14. The exhaust gas purification apparatus according to claim 21 , wherein oxygen and / or air is added upstream of the exhaust gas purification catalyst or in the exhaust gas purification catalyst so as to be 6 or more. A temperature detector is added to the catalyst component layer of the exhaust gas purification catalyst, and an A / F detector is added in the vicinity of the outlet. When the detected value of the temperature detector reaches 110 ° C. or higher, the A / F detector The exhaust gas purification according to claim 21 , wherein oxygen and / or air is added upstream of the exhaust gas purification catalyst or in the exhaust gas purification catalyst so that the gas becomes 14.6 or more. apparatus. When an A / F detector is added in the vicinity of the inlet and the outlet of the exhaust gas purifying catalyst, and hydrocarbon desorption is detected from the detection values of the A / F detectors installed in the vicinity of the inlet and the outlet. Then, oxygen and / or air are introduced upstream of the exhaust gas purification catalyst or into the exhaust gas purification catalyst so that the A / F detector disposed in the vicinity of the outlet becomes A / F = 14.6 or more. The exhaust gas purification device according to claim 21 , wherein the exhaust gas purification device is added. Wherein the Pd-containing catalyst and the catalyst for the exhaust gas purification is Rh, any claim 17 to 24 in which Rh content of the Pd-containing catalyst is equal to or less than Rh content of the exhaust gas purifying catalyst The exhaust gas purifying device according to any one of the items. 26. One or more of the claims 19 to 25 , wherein one or more other exhaust gas purification catalysts identical to the exhaust gas purification catalyst are added downstream of the exhaust gas purification catalyst. The exhaust gas purifying device according to 1. 27. The exhaust gas purification catalyst according to claim 26 , wherein the exhaust gas purification catalyst and the one or more other exhaust gas purification catalysts are provided at different positions from the engine to which they are mounted. apparatus.

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