JP4298071B2 - Exhaust gas purification material and method for producing the same - Google Patents

Description

【０１８１】
（数１）において、ＰＣＯはＮＤＩＲ方式の一酸化炭素、二酸化炭素ガス分析計によって測定された一酸化炭素濃度の値、ＰＣＯ₂はＮＤＩＲ方式の一酸化炭素、二酸化炭素ガス分析計によって測定された二酸化炭素濃度の値、ＰＣは炭化水素が１００％燃焼した時のＣＯ₂濃度の理論値である。
【０１８２】
一方、浄化された混合ガスの内、他の一部はガスサンプリング装置を介してガスクロマトグラフ５０へ導入され、未反応の炭化水素の各成分が定量される。反応に伴う分解率は、排ガス浄化材４８を配置しない状態で、前もって炭化水素の各成分の定量を行い、この時の値を１００％として、浄化された混合ガス中に含まれる未反応の炭化水素の残存率より算出した。
【０１８３】
次に、ＳＯ₂酸化能評価試験について説明する。
【０１８４】
図９はＳＯ₂酸化能評価試験に用いた反応装置の概略図である。
【０１８５】
図９において、５１はＳＯ₂酸化能評価試験を行う反応装置、５２、５３、５４は気体用流量調整器、５５はガス混合器、５６は石英管、５７は電気炉、５８は石英ウール、５９は排ガス浄化材、６０はＮＤＩＲ方式のＳＯ₂ガス分析計である。
【０１８６】
以上のように構成された反応装置を用いて行われるＳＯ₂酸化能評価試験方法について説明する。
【０１８７】
気体用流量調整器５２、５３、５４によって流量調整された窒素ガス、乾燥した大気、ＳＯ₂ガス（ＳＯ₂濃度＝１０００ｐｐｍ、バランスガス＝窒素）は混合器５５で混合され、石英管５６内に導入され、石英管５６内に置かれた排ガス浄化材５９によって反応する。ここで、試験に供する排ガス浄化材５９は、反応系で評価することができるように、所定の寸法に切り出した。また、排ガス浄化材５９の前後には、石英ウール５８が配置され、石英管５６は電気炉５７内に設置されている。その後、反応したガスは、ＮＤＩＲ方式のＳＯ₂ガス分析計６０に導入され、ＳＯ₂濃度を測定する。
【０１８８】
ここで、ＳＯ₂酸化能評価試験は、混合ガスの酸素分圧８％、空間速度３００００ｈ^-1、ＳＯ₂濃度１００ｐｐｍ、電気炉５７内温度４００℃の条件で行われ、触媒活性の経時変化が測定された。
【０１８９】
ＳＯ₂酸化能は、石英管５６に導入される前のＳＯ₂濃度と、ＳＯ₂分析計で測定されたＳＯ₂濃度により評価した。
【０１９０】
（表１）乃至（表１７）に、実施例１〜５及び比較例１〜６で製造された排ガス浄化材５９における触媒活性評価試験及びＳＯ₂酸化能評価試験の結果を示す。
【０１９１】
（表１）に、担体である活性アルミナの平均粒子径（μｍ）、Ｎ₂吸着法による細孔分布測定における全細孔容積（ｍｌ／ｇ）、細孔直径１００Å以上の細孔容積の存在率（％）、大気中１０００℃で焼成後の比表面積（ｍ²／ｇ）及び２５０℃での炭化水素浄化率（％）を示した。
【０１９２】
【表１】

【０１９３】
（表１）から明らかなように、活性アルミナについては、平均粒子径が１μｍ〜１０μｍ、Ｎ₂吸着法による細孔分布測定における全細孔容積が０．３ｍｌ／ｇ以上、細孔直径１００Å以上の細孔容積の存在率が６０％以上、大気中１０００℃で焼成後の比表面積が１００ｍ²／ｇ以上で、炭化水素の浄化率が８０％以上を示した。一方、前記範囲外の活性アルミナを使用した場合、炭化水素の浄化率が４０％〜６０％であった。このように、前記範囲内にある活性アルミナを使用すると、高活性な排ガス浄化材が得られることがわかった。
【０１９４】
（表２）に、担体基材に対する被覆量（ｗｔ％）と２５０℃での炭化水素浄化率（％）との関係を示した。
【０１９５】
【表２】

【０１９６】
この（表２）から明らかなように、基材に対し酸性酸化物を被覆した担体が７ｗｔ％〜１５ｗｔ％において炭化水素の浄化率が８５％であり、前記範囲外の被覆量の４５％〜６０％に比べて炭化水素の浄化率が高いことがわかった。
【０１９７】
（表３）に、基材に対するシリカとアルミナからなる複合酸化物の被覆量（ｗｔ％）と２５０℃での炭化水素浄化率（％）との関係を示した。
【０１９８】
【表３】

【０１９９】
この（表３）から明らかなように、アルミナに対するシリカとアルミナからなる複合酸化物の被覆量が７ｗｔ％〜１５ｗｔ％で、炭化水素の浄化率が９５％〜９６％と高く、上記範囲外の被覆量では、４８％〜６０％と低くなることが明らかである。
【０２００】
次に（表４）に、基材に対するシリカとチタニアからなる複合酸化物の被覆量（ｗｔ％）と２５０℃での炭化水素浄化率（％）との関係を示した。
【０２０１】
【表４】

【０２０２】
この（表４）から明らかなように、アルミナに対するシリカとチタニアからなる複合酸化物の被覆量が７ｗｔ％〜１５ｗｔ％で、炭化水素の浄化率が９３％〜９５％と高く、上記範囲外の被覆量では、５０％〜５９％と低くなることが明らかである。
【０２０３】
次に（表５）に、酸性酸化物を被覆した担体のスラリーの粘度（ｃＰ）と２５０℃での炭化水素浄化率（％）との関係を示した。
【０２０４】
【表５】

【０２０５】
この（表５）から明らかなように、排ガス浄化材の製造方法における、酸性酸化物を被覆した担体のスラリーの粘度が１ｃＰ〜３００ｃＰにおいて炭化水素の浄化率が７０％〜８５％であり、前記範囲外のスラリーの粘度の５０％〜５５％に比べて炭化水素の浄化率が高いことがわかった。
【０２０６】
次に（表６）に、シリカとアルミナからなる複合酸化物を被覆した担体のスラリーの粘度（ｃＰ）と２５０℃での炭化水素浄化率（％）との関係を示した。
【０２０７】
【表６】

【０２０８】
この（表６）から明らかなように、シリカとアルミナからなる複合酸化物を被覆した担体のスラリーの粘度が１ｃＰ〜３００ｃＰにおいて炭化水素の浄化率が７０％〜９６％であり、前記範囲外のスラリーの粘度の５３％〜５４％に比べて炭化水素の浄化率が高いことがわかった。
【０２０９】
（表７）に、シリカとチタニアからなる複合酸化物を被覆した担体のスラリーの粘度（ｃＰ）と２５０℃での炭化水素浄化率（％）との関係を示した。
【０２１０】
【表７】

【０２１１】
この（表７）から明らかなように、シリカとチタニアからなる複合酸化物を被覆した担体のスラリーの粘度が１ｃＰ〜３００ｃＰにおいて炭化水素の浄化率が８２％〜９６％であり、前記範囲外のスラリーの粘度の５１％〜５５％に比べて炭化水素の浄化率が高いことがわかった。
【０２１２】
次に（表８）に、シリカの出発原料と２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）との関係を示した。
【０２１３】
【表８】

【０２１４】
この（表８）から明らかなように、排ガス浄化材の製造においてシリカを形成する場合に、出発原料として珪素アルコキシドを用いた場合、炭化水素の浄化率が８５％と高く、ＳＯ₂の硫酸ミストへの酸化が１５％で抑制効果が大きいことがわかった。また、出発原料としてシリカゾルを用いた場合、炭化水素の浄化率が７５％、ＳＯ₂の酸化率が２５％であり、更に、珪酸ナトリウムを用いた場合、炭化水素の浄化率が５０％、ＳＯ₂の酸化率が４０％であった。
【０２１５】
次に（表９）に、シリカの出発原料、アルミナの出発原料と２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）との関係を示した。
【０２１６】
【表９】

【０２１７】
この（表９）から明らかなように、排ガス浄化材の製造方法においてシリカとアルミナからなる複合酸化物を形成する場合に、出発原料としてシリカ分は珪酸ナトリウムを、アルミナ分は硝酸アルミニウムを用いた場合に、炭化水素の浄化率が９７％と高く、ＳＯ₂の硫酸ミストへの酸化が９％と抑制効果が大きいことがわかった。一方、出発原料としてシリカ分はケイ酸ナトリウム、アルミナ分は水酸化ナトリウムを、又は、シリカ分はシリカゾルを、アルミナ分は硝酸アルミニウムを用いた場合に、更には、シリカ分はシリカゾルを、アルミナ分は水アルミナをそれぞれ用いた場合、炭化水素の浄化率が５０％〜７１％、ＳＯ₂の酸化率が２５％〜４０％であった。
【０２１８】
（表１０）に、シリカの出発原料、チタニアの出発原料と２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）との関係を示した。
【０２１９】
【表１０】

【０２２０】
この（表１０）から明らかなように、排ガス浄化材の製造方法においてシリカとチタニアからなる複合酸化物を形成する場合に、出発原料としてシリカ分は珪酸ナトリウムを、チタニア分は塩化チタンを用いた場合に、炭化水素の浄化率が９６％と高く、ＳＯ₂の硫酸ミストへの酸化が９％と抑制効果が大きいことがわかった。一方、出発原料としてシリカ分は珪酸ナトリウム、チタニア分は硫酸チタンを、又は、シリカ分はシリカゾルを、チタニア分は塩化チタンを用いた場合に、更には、シリカ分はシリカゾルを、チタニア分は硫酸チタンをそれぞれ用いた場合、炭化水素の浄化率が６２％〜７５％、ＳＯ₂の酸化率が３５％〜４２％であった。
【０２２１】
次に（表１１）に、シリカとアルミナからなる複合酸化物のＡｌ／（Ｓｉ・Ａｌ）の比率と２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）との関係を示した。
【０２２２】
【表１１】

【０２２３】
また、（表１２）に、シリカとチタニアからなる複合酸化物のＴｉ／（Ｓｉ・Ｔｉ）の比率と２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）との関係を示した。
【０２２４】
【表１２】

【０２２５】
この（表１１）、（表１２）から、シリカとアルミナからなる複合酸化物のＡｌ／（Ｓｉ・Ａｌ）の比率と、シリカとチタニアからなる複合酸化物のＴｉ／（Ｓｉ・Ｔｉ）の比率を４０〜８０にすると、炭化水素の浄化率が９０％以上、ＳＯ₂の硫酸ミストへの酸化が１０％以下と抑制効果が大きいことがわかった。一方、前記範囲外では、炭化水素の浄化率が５１％〜５３％、ＳＯ₂の酸化率が４１％〜４４％であった。
【０２２６】
次に（表１３）に、実施例１〜５における酸性酸化物を形成する場合の一次焼成温度と２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）との関係を示した。
【０２２７】
【表１３】

【０２２８】
この（表１３）から明らかなように、実施例１〜３より、排ガス浄化材の製造において酸性酸化物を形成する場合の一次焼成する際の焼成温度が５００℃〜１０００℃において、炭化水素の浄化率が８０％以上と高く、ＳＯ₂の硫酸ミストへの酸化が２０％以下と抑制効果が大きいことがわかった。前記範囲外の焼成温度では、炭化水素の浄化率が５２％〜５５％、ＳＯ₂の酸化率が４０％〜４６％であった。
【０２２９】
実施例４より、シリカとアルミナからなる複合酸化物を形成する場合の一次焼成する際の焼成温度が４００℃〜８００℃において、炭化水素の浄化率が９１％以上と高く、ＳＯ₂の硫酸ミストへの酸化が１０％以下と抑制効果が大きいことがわかった。前記範囲外の焼成温度では、炭化水素の浄化率が５５％〜５９％、ＳＯ₂の酸化率が３７％〜４１％であった。
【０２３０】
実施例５より、シリカとチタニアからなる複合酸化物を形成する場合の一次焼成する際の焼成温度が４００℃〜８００℃において、炭化水素の浄化率が９０％以上と高く、ＳＯ₂の硫酸ミストへの酸化が１０％以下と抑制効果が大きいことがわかった。前記範囲外の焼成温度では、炭化水素の浄化率が５６％〜６１％、ＳＯ₂の酸化率が４２％〜４５％であった。
【０２３１】
次に（表１４）に、担体層で被覆された基材を触媒成分を含有する溶液中に含浸した後、凍結乾燥法を用いて形成した場合と、乾燥機を用いて形成した場合の排ガス浄化材について、２５０℃での炭化水素浄化率（％）と４００℃でのＳＯ₂の酸化率（％）を示した。
【０２３２】
【表１４】

【０２３３】
この（表１４）から明らかなように、凍結乾燥法を用いた場合と、乾燥機を用いた場合を比較すると、ＳＯ₂の酸化率については大きな差はないが、炭化水素の浄化率については凍結乾燥法を用いた方が明らかに高く、高活性な排ガス浄化材が得られることがわかった。
【０２３４】
次に（表１５）に、実施例１〜３、（表１６）に、実施例４，５、及び（表１７）に比較例１〜４における酸性酸化物を形成する場合の被覆量（ｗｔ％）、膜厚（μｍ）、被覆率（％）、２５０℃での炭化水素浄化率（％）及び４００℃でのＳＯ₂の酸化率（％）を示した。
【０２３５】
【表１５】

【０２３６】
【表１６】

【０２３７】
【表１７】

【０２３８】
この（表１５）〜（表１７）から明らかなように、実施例１〜３より、担体に対する酸性酸化物の被覆量が６ｗｔ％〜１０ｗｔ％、酸性酸化物層の膜厚が０．１μｍ〜２０μｍ、担体に対する被覆率が８０％〜１００％で、炭化水素の浄化率が８４％以上、ＳＯ₂の酸化率が１３％以下を示した。一方、前記範囲外の場合、炭化水素の浄化率が４６％〜５６％、ＳＯ₂の酸化率が３９％〜４５％であった。
【０２３９】
また、比較例１より、酸性酸化物が存在しない場合は、炭化水素の浄化率が６５％、ＳＯ₂の酸化率が５１％であった。これにより、酸性酸化物の存在により、炭化水素の浄化率、硫酸ミストへの酸化抑制効果が良好であることがわかった。
【０２４０】
更に、比較例２より、比較例２の製造方法で作製した排ガス浄化材は、炭化水素の浄化率が６９％〜７１％、ＳＯ₂の酸化率が２５％〜２６％であり、実施例１〜５の炭化水素の浄化率が８４％以上、ＳＯ₂の酸化率が１３％以下に比べ、排ガス浄化材の性能が劣ることがわかった。
【０２４１】
実施例４、５より、担体に対する複合酸化物の被覆量が６ｗｔ％〜１０ｗｔ％、酸性酸化物層の膜厚が０．１μｍ〜２０μｍ、担体に対する被覆率が８０％〜１００％で、炭化水素の浄化率が９４％以上、ＳＯ₂の酸化率が９％以下を示した。一方、前記範囲外の場合、炭化水素の浄化率が４６％〜５６％、ＳＯ₂の酸化率が３９％〜４５％であった。
【０２４２】
実施例４と比較例３を比較すると、実施例４では炭化水素の浄化率が９４％以上、ＳＯ₂の酸化率が９％以下と高く、比較例３における炭化水素の浄化率が８４％〜８６％、ＳＯ₂の酸化率が１３％以下に比べて高活性な排ガス浄化材が得られることがわかった。
【０２４３】
【発明の効果】
以上述べたように本発明においては、以下の優れた効果を実現することができる。
【０２４７】
本発明の請求項１に記載の排ガス浄化材によれば、基材と、前記基材表面に形成された担体層と、前記担体層の表面に５００℃〜１０００℃で焼成して被覆された酸性酸化物層と、前記酸性酸化物層の表面に担持された触媒成分と、を備え、前記酸性酸化物層を被覆した前記担体のスラリー中に前記基材を含浸し焼成して前記基材上に前記酸性酸化物層を被覆した担体層を形成し、前記酸性酸化物層が珪素アルコキシドを出発原料（前駆体）とするシリカであり、前記基材に対し前記酸性酸化物を被覆した前記担体が７ｗｔ％〜１５ｗｔ％であり、前記酸性酸化物を被覆した前記担体のスラリーの粘度が１ｃＰ〜３００ｃＰであり、前記担体に対する前記酸性酸化物の被覆量が６ｗｔ％〜１０ｗｔ％、前記酸性酸化物層の膜厚が０．１μｍ〜２０μｍ、前記担体に対する前記酸性酸化物の被覆率が８０％〜１００％であり、前記担体層の担体が、平均粒子径が１μｍ〜１０μｍ、Ｎ^２吸着法による細孔分布測定法において全細孔容積が０．３ｍｌ／ｇ以上で、かつ細孔直径１００Å以上の細孔容積が全細孔容積の６０％以上、更に大気中１０００℃で焼成後の比表面積が１００ｍ^２／ｇ以上の耐熱性無機酸化物からなるので、硫黄酸化物の存在下においても硫黄酸化物による被毒を受け難く、耐久性に優れるという有利な効果の他、排ガスの炭化水素を効率よく浄化できるという有利な効果が得られる。また、本発明の請求項２に記載の排ガス浄化材によれば、基材と、前記基材表面に形成された担体層と、前記担体層の表面に４００℃〜８００℃で焼成して被覆された酸性酸化物層と、前記酸性酸化物層の表面に前記担体層で被覆された基材を触媒成分を含有する溶液中に含浸した後凍結乾燥後焼成して担持された触媒成分と、を備え、前記酸性酸化物層を被覆した前記担体のスラリー中に前記基材を含浸し焼成して前記基材上に前記酸性酸化物層を被覆した担体層を形成し、前記酸性酸化物層が、シリカとアルミナ、あるいはシリカとチタニアを用いて形成された複合酸化物であり、前記複合酸化物がシリカとアルミナからなる場合は出発原料としてシリカは珪酸ナトリウムをアルミナは硝酸アルミニウムを用いＡｌ／（Ｓｉ・Ａｌ）の比率を４０〜８０にしたものであり、前記複合酸化物がシリカとチタニアからなる場合は出発原料としてシリカは珪酸ナトリウムをチタニアは塩化チタンを用いＴｉ／（Ｓｉ・Ｔｉ）の比率を４０〜８０にしたものであり、前記基材に対し前記複合酸化物を被覆した前記担体が７ｗｔ％〜１５ｗｔ％であり、前記複合酸化物を被覆した前記担体のスラリーの粘度が１ｃＰ〜３００ｃＰであり、前記担体に対する前記複合酸化物の被覆量が６ｗｔ％〜１０ｗｔ％、前記酸性酸化物層の膜厚が０．１μｍ〜２０μｍ、前記担体に対する複合酸化物の被覆率が８０％〜１００％であり、前記担体層の担体が、平均粒子径が１μｍ〜１０μｍ、Ｎ^２吸着法による細孔分布測定法において全細孔容積が０．３ｍｌ／ｇ以上で、かつ細孔直径１００Å以上の細孔容積が全細孔容積の６０％以上、更に大気中１０００℃で焼成後の比表面積が１００ｍ^２／ｇ以上の耐熱性無機酸化物からなることを特徴とする排ガス浄化材としたものであり、硫黄酸化物の存在下においても硫黄酸化物による被毒を受け難く、耐久性に優れるという有利な効果の他、排ガスの炭化水素を効率よく浄化できるという有利な効果が得られる。
【０２４８】
全細孔容積が０．３ｍｌ／ｇ以上で、かつ細孔直径１００Å以上の細孔容積が全細孔容積の６０％以上の担体を用いているので、バイモーダル構造を有し、触媒活性表面積を増大し浄化効率を高めるという効果が得られる。
【０２４９】
担体がバイモーダル構造で触媒粒子のシンタリングを防ぎ触媒活性の耐久性を向上させるという効果が得られる。
【０２５０】
担体の比表面積が１００ｍ²／ｇ以上有するので、詳細は不明であるが、スピルオーバー現象等により炭化水素を効率的に酸化分解することができるという効果が得られる。
【０２５１】
硫黄酸化物とシリカ、アルミナ、チタニア、ジルコニア、酸化亜鉛の内少なくとも２種類以上を用いた複合酸化物層との反発作用によって、硫黄酸化物による被毒を受け難く、耐久性に優れるという有利な効果が得られる。
【０２５２】
酸性酸化物層が珪素アルコキシドを前駆体とするシリカであるので、珪素アルコキシドを用いることにより、含浸法という簡単な方法で均一なシリカの被覆層を担体上に形成できるという有利な効果が得られる。
【０２５３】
酸性酸化物層が珪酸ナトリウムを前駆体とするシリカと、硝酸アルミニウムを前駆体とするアルミナとからなる複合酸化物であるので、珪酸ナトリウムと硝酸アルミニウムを用いて酸性酸化物を形成し、含浸法という簡単な方法でシリカとアルミナからなる均一な被覆層を担体上に形成できるという有利な効果が得られる。
【０２５４】
酸性酸化物層のシリカとアルミナからなる複合酸化物のＡｌ／（Ｓｉ・Ａｌ）の比率が、４０〜８０であるので、硫黄酸化物と複合酸化物が酸性同士で反発しあうことにより硫黄酸化物が触媒成分及び担体層により近づきにくくなるという有利な効果が得られる。
【０２５５】
酸性酸化物層が珪酸ナトリウムを前駆体とするシリカと、塩化チタンを前駆体とするチタニアとからなる複合酸化物であるので、塩化チタンと珪酸ナトリウムを用いて酸性酸化物を形成し、含浸法という簡単な方法でシリカとチタニアからなる均一な被覆層を担体上に形成できるという有利な効果が得られる。
【０２５６】
シリカとチタニアからなる複合酸化物のＴｉ／（Ｓｉ・Ｔｉ）の比率が４０〜８０であるので、硫黄酸化物と複合酸化物が酸性同士で反発しあうことにより硫黄酸化物が触媒成分及び担体層により近づきにくくなるという有利な効果が得られる。
【０２５９】
本発明の排ガス浄化材の製造方法によれば、硝酸アルミニウム水溶液に担体を加えて混合・攪拌し、珪酸ナトリウム水溶液と水酸化ナトリウム水溶液の混合溶液を加え、担体の表面にシリカとアルミナからなる複合酸化物の前駆体を含浸後、一次焼成して担体の表面にシリカとアルミナからなる複合酸化物を被覆した後に、複合酸化物を被覆した担体のスラリーを作製し、スラリー中に基材を含浸し、次いで二次焼成して、基材上に複合酸化物層を被覆した担体層を形成し、次いで担体層で被覆された基材を、触媒成分を含有する溶液中に含浸した後に三次焼成するので、酸性溶液中にアルミナを加えると、アルミナの等電点（ｐＨ＝８〜１０）における凝集を抑制することができ、アルミナ上にシリカとアルミナからなる複合酸化物層を均一に形成できるという有利な効果が得られる。
【０２６１】
本発明の排ガス浄化材の製造方法によれば、塩化チタン水溶液に担体を加えて混合・攪拌し、次いで、珪酸ナトリウム水溶液を加え、担体の表面にシリカとチタニアからなる複合酸化物の前駆体を含浸後、一次焼成して担体の表面にシリカとチタニアからなる複合酸化物を被覆した後、複合酸化物を被覆した担体のスラリーを作製し、スラリー中に基材を含浸し、次いで二次焼成して、基材上に複合酸化物層を被覆した担体層を形成し、次いで担体層で被覆された基材を、触媒成分を含有する溶液中に含浸した後、三次焼成するので、酸性の溶液中にアルミナを加えると、アルミナの等電点（ｐＨ＝８〜１０）における凝集を抑制することができ、アルミナ上にチタニアとシリカからなる複合酸化物層を均一に形成できるという有利な効果が得られる。
【０２６３】
酸性酸化物を被覆した担体のスラリーの粘度が１ｃＰ〜３００ｃＰであるので、簡単な方法で均一な被覆層を基材に形成でき、排ガス中の炭化水素を効率よく浄化できるという有利な効果が得られる。
【０２６４】
酸性酸化物の前駆体の溶液中に担体を含浸後、一次焼成して前記担体表面に酸性酸化物層を被覆するが、その一次焼成する際の焼成温度が、５００℃〜１０００℃であるので、酸性ガスである硫黄酸化物と酸性酸化物との間の反発作用が良好であるという有利な効果が得られる。
【０２６５】
複合酸化物の前駆体を担体に含浸後、一次焼成する際の焼成温度が、４００℃〜８００℃であるので、酸性ガスである硫黄酸化物と複合酸化物との間の反発作用が良好であり、耐久性に優れるという有利な効果が得られる。
【図面の簡単な説明】
【図１】本発明の実施の形態１における排ガス浄化材の断面図
【図２】実施の形態１における排ガス浄化材の製造工程のフローチャート
【図３】実施の形態２における排ガス浄化材の製造工程のフローチャート
【図４】本発明の実施の形態４における排ガス浄化材の断面図
【図５】実施の形態４の排ガス浄化材の製造工程のフローチャート
【図６】本発明の実施の形態５における排ガス浄化材の断面図
【図７】実施の形態５の排ガス浄化材の製造工程のフローチャート
【図８】触媒活性評価試験に用いた固定床流通系反応装置の概略図
【図９】ＳＯ₂酸化能評価試験に用いた反応装置の概略図
【符号の説明】
１ 排ガス浄化材
２ 基材
３ 担体層
４ 酸性酸化物層
５ 触媒成分
２１ 排ガス浄化材
２２ 基材
２３ アルミナ層
２４ 複合酸化物層
２５ 触媒成分
３０ 排ガス浄化材
３１ 基材
３２ アルミナ層
３３ 複合酸化物層
３４ 触媒成分
４０ 固定床流通系反応装置
４１、４２ 気体用流量調整器
４３ 液体用流量調整器
４４ 気化器
４５ 石英管
４６ 電気炉
４７ 石英ウール
４８ 排ガス浄化材
４９ ＮＤＩＲ方式のＣＯ，ＣＯ₂ガス分析計
５０ ガスクロマトグラフ
５１ 反応装置
５２、５３、５４ 気体用流量調整器
５５ ガス混合器
５６ 石英管
５７ 電気炉
５８ 石英ウール
５９ 排ガス浄化材
６０ ＮＤＩＲ方式のＳＯ₂ガス分析計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purifying material for purifying exhaust gas from an internal combustion engine and a method for producing the same, and more particularly to an exhaust gas purifying material for purifying particulates contained in exhaust gas from a diesel engine by oxidizing combustion and a method for producing the same.
[0002]
[Prior art]
In recent years, due to the increase in the environment, after purifying exhaust gas from an internal combustion engine, it is desired to be released into the atmosphere as safe exhaust gas, and various exhaust gas purifying materials used to purify exhaust gas have been studied. Has been.
[0003]
Generally, an exhaust gas purifying material is made of a ceramic or metal heat-resistant honeycomb structure, and an inorganic material for supporting a required amount of a noble metal, nonmetal or oxide thereof as a catalytic active component on the heat-resistant honeycomb structure. It is comprised from the support | carrier (or support | carrier layer) which consists of a porous material, and the noble metal and nonmetal which are the catalyst active components carry | supported on the support | carrier, or those oxides.
[0004]
As for gasoline engines, strict emission regulations for harmful components in exhaust gas and technological advances therefor, specifically, the emergence and further improvement of three-way catalysts, have definitely reduced the harmful substances in exhaust gas. . However, because of the unique principle of diesel engines and the presence of harmful components called particulates, regulations were set more loosely than gasoline engines. It was far behind.
[0005]
However, due to the recent increase in interest in the environment, emission regulations for toxic substances have been strengthened for diesel engines, and development of exhaust gas purification materials that can reliably purify exhaust gas from diesel engines is eagerly desired.
[0006]
Therefore, an open type SOF (Soluble Organic Fraction: Soluble Organic Component, High-boiling point hydrocarbon) catalyst having a structure in which all of the holes at both ends are basically the same as a three-way catalyst capable of purifying exhaust gas from a diesel engine is provided. Has been developed.
[0007]
For example, JP-A-1-171626 (hereinafter referred to as “I”) discloses that, as in gasoline engines, metal fine particles such as platinum group metals, which are catalytically active components, have high specific surface area activated alumina, alkali metals, An open-type SOF decomposition catalyst is disclosed which is dispersed and supported on a support such as activated alumina to which a rare earth is added, and which oxidizes and purifies SOF in diesel particulates together with carbon monoxide and hydrocarbons.
[0008]
Japanese Patent Laid-Open No. 4-358539 (hereinafter referred to as “B”) discloses “SiO 2 on an activated alumina layer carrying a catalytic metal.₂TiO₂And ZrO₂A sulfur dioxide resistant catalyst is disclosed in which an oxide film is formed by chemical vapor deposition of at least one oxide of the above and sulfur oxide is not adsorbed on activated alumina.
[0009]
Japanese Patent Publication No. 55-26912 (hereinafter referred to as “C”) discloses “a sulfur dioxide resistant catalyst for coating a ceramic substrate by mixing alumina and amorphous silica, preferably silica sol in an aqueous medium”. Yes.
[0010]
[Problems to be solved by the invention]
However, the above conventional open type SOF decomposition catalyst has the following problems.
[0011]
The open-type SOF decomposition catalyst and sulfur dioxide-resistant catalyst described in the Gazette No. 1 are effective when the sulfur oxide resulting from the fuel contained in the diesel exhaust gas reacts with the alumina that is the carrier to sulphate the alumina. As a result, the specific surface area is reduced, the catalytic activity is lowered, and the durability is insufficient.
[0012]
The open-type SOF decomposition catalyst described in the publication No. 2 has a problem that a process for forming an oxide is complicated and a production cost is high because a chemical vapor deposition method is used.
[0013]
Since the open-type SOF decomposition catalyst described in C. uses amorphous silica, silica cannot be uniformly formed on alumina, and partially exposed alumina reacts with sulfur oxides to form sulfur. The chlorination has a problem that the specific surface area decreases and the catalytic activity decreases.
[0014]
The present invention solves the above-described conventional problems, and provides an exhaust gas purifying material capable of purifying exhaust gas components from an internal combustion engine, particularly a diesel engine, even in the presence of sulfur oxide, and a manufacturing method with a simple manufacturing process thereof. The purpose is to do.
[0015]
[Means for Solving the Problems]
  In order to solve the above problems, an exhaust gas purifying material according to claim 1 of the present invention is a base material, a carrier layer formed on the surface of the base material, and fired at 500 to 1000 ° C. on the surface of the carrier layer. An acidic oxide layer coated on the surface of the acidic oxide layer, and a catalyst component supported on the surface of the acidic oxide layer, and the substrate is impregnated in a slurry of the carrier coated with the acidic oxide layer and fired. Then, a carrier layer coated with the acidic oxide layer is formed on the base material, and the acidic oxide layer is silica using silicon alkoxide as a starting material (precursor), and the acidic oxidation is performed on the base material. The carrier coated with the product is 7 wt% to 15 wt%, the slurry of the carrier coated with the acidic oxide has a viscosity of 1 cP to 300 cP, and the coating amount of the acidic oxide on the carrier is 6 wt% to 10 wt% % Of the acidic oxide layer Thickness 0.1Myuemu～20myuemu, wherein a coating ratio of 80% to 100% of the acidic oxide to the carrier, the carrier of the carrier layer has an average particle diameter of 1 m to 10 m, N²In the pore distribution measurement method by the adsorption method, the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume.After firing at 1000 ° C in the atmosphereSpecific surface area is 100m²/ G or more heat-resistant inorganic oxide. The exhaust gas purifying material according to claim 2 of the present invention is coated with a base material, a carrier layer formed on the surface of the base material, and a surface of the carrier layer baked at 400 ° C. to 800 ° C. The acidic oxide layer and the surface of the acidic oxide layer are covered with the carrier layer.GroupAnd impregnating the base material in a slurry of the carrier coated with the acidic oxide layer. Forming a carrier layer coated with the acidic oxide layer on the substrate, and the acidic oxide layer is a composite oxide formed using silica and alumina, or silica and titania, and the composite When the oxide is composed of silica and alumina, the silica is sodium silicate as the starting material, the alumina is aluminum nitrate and the Al / (Si · Al) ratio is 40 to 80, and the composite oxide is silica and In the case of titania, the starting material is silica with sodium silicate and titania with titanium chloride, and the ratio of Ti / (Si · Ti) is 40 to 80. The carrier coated with the complex oxide is 7 wt% to 15 wt%, the viscosity of the slurry of the carrier coated with the complex oxide is 1 cP to 300 cP, and the coating amount of the complex oxide on the carrier is 6 wt% 10 wt%, the thickness of the acidic oxide layer is 0.1 μm to 20 μm, the coverage of the composite oxide with respect to the carrier is 80% to 100%, and the carrier of the carrier layer has an average particle diameter of 1 μm to 10 μm, N²In the pore distribution measurement method by the adsorption method, the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume.After firing at 1000 ° C in the atmosphereSpecific surface area is 100m²The exhaust gas purifying material is characterized by comprising a heat-resistant inorganic oxide of at least / g. The exhaust gas purification material according to claim 3 of the present invention is the exhaust gas purification material according to claim 1 or 2, wherein the carrier is alumina or activated alumina.
[0016]
  This configuration, SulfurThe effect of not being easily poisoned by sulfur oxides even in the presence of yellow oxidesIn addition, it can efficiently purify hydrocarbons in exhaust gasHave
[0033]
DETAILED DESCRIPTION OF THE INVENTION
  The exhaust gas purifying material according to claim 1 of the present invention is a base material, a carrier layer formed on the surface of the base material, and an acidic oxidation coated on the surface of the carrier layer by baking at 500 ° C. to 1000 ° C. And a catalyst component supported on the surface of the acidic oxide layer, impregnated with the base material in a slurry of the carrier coated with the acidic oxide layer, and baked on the base material A carrier layer coated with the acidic oxide layer is formed, the acidic oxide layer is silica using silicon alkoxide as a starting material (precursor), and the carrier coated with the acidic oxide on the substrate is The viscosity of the slurry of the carrier coated with the acidic oxide is 7 wt% to 15 wt%, the coating amount of the acidic oxide on the carrier is 6 wt% to 10 wt%, and the acidic oxide layer Film thickness of 0.1 μm to 20 μm The coverage of the acidic oxide with respect to the carrier is 80% to 100%, and the carrier of the carrier layer has an average particle diameter of 1 μm to 10 μm, N²In the pore distribution measurement method by the adsorption method, the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume.After firing at 1000 ° C in the atmosphereSpecific surface area is 100m²/ G or more heat-resistant inorganic oxide. The exhaust gas purifying material according to claim 2 of the present invention is coated with a base material, a carrier layer formed on the surface of the base material, and a surface of the carrier layer baked at 400 ° C. to 800 ° C. The acidic oxide layer and the surface of the acidic oxide layer are covered with the carrier layer.GroupAnd impregnating the base material in a slurry of the carrier coated with the acidic oxide layer. Forming a carrier layer coated with the acidic oxide layer on the substrate, and the acidic oxide layer is a composite oxide formed using silica and alumina, or silica and titania, and the composite When the oxide is composed of silica and alumina, the silica is sodium silicate as the starting material, the alumina is aluminum nitrate and the Al / (Si · Al) ratio is 40 to 80, and the composite oxide is silica and In the case of titania, the starting material is silica with sodium silicate and titania with titanium chloride, and the ratio of Ti / (Si · Ti) is 40 to 80. The carrier coated with the complex oxide is 7 wt% to 15 wt%, the viscosity of the slurry of the carrier coated with the complex oxide is 1 cP to 300 cP, and the coating amount of the complex oxide on the carrier is 6 wt% 10 wt%, the thickness of the acidic oxide layer is 0.1 μm to 20 μm, the coverage of the composite oxide with respect to the carrier is 80% to 100%, and the carrier of the carrier layer has an average particle diameter of 1 μm to 10 μm, N²In the pore distribution measurement method by the adsorption method, the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume.After firing at 1000 ° C in the atmosphereSpecific surface area is 100m²The exhaust gas purifying material is characterized by comprising a heat-resistant inorganic oxide of at least / g. The exhaust gas purification material according to claim 3 of the present invention is the exhaust gas purification material according to claim 1 or 2, wherein the carrier is alumina or activated alumina.
[0034]
  With this configuration,It is difficult to be poisoned by sulfur oxides even in the presence of sulfur oxides.In addition to the function, it has an effect of efficiently purifying hydrocarbons in exhaust gas.
[0035]
Uses a carrier with a total pore volume of 0.3 ml / g or more and a pore diameter of 100 mm or more and a pore volume of 60% or more, so it has a bimodal structure and increases the catalytic active surface area for purification. It has the effect of increasing efficiency.
[0036]
The carrier has a bimodal structure and prevents the catalyst particles from sintering, thereby improving the durability of the catalyst activity.
[0037]
The specific surface area of the carrier is 100m²Since it has / g or more, the details are unknown, but it has the effect that hydrocarbons can be efficiently oxidized and decomposed by a spillover phenomenon or the like.
[0038]
Here, a carrier having an average particle diameter in the range of 1 μm to 10 μm is used. As the average particle size becomes smaller than 1 μm, the particle size is too small and it is difficult to obtain an optimal bimodal structure, the hydrocarbon purification efficiency decreases, and as the particle size becomes larger than 10 μm, the surface area decreases. Since there is a tendency for the purification efficiency of hydrocarbons to decrease, neither is preferable.
[0039]
A carrier having a total pore volume of 0.3 ml / g or more is used. This is to keep the catalyst particles in the pores and prevent sintering. As the total pore volume becomes smaller than 0.3 ml / g, the catalyst particles tend to sinter on the surface of the support, and the hydrocarbon purification efficiency tends to decrease, which is not preferable.
[0040]
A carrier having a pore diameter of 100 mm or more is used. As the pore diameter becomes smaller than 100 mm, the hydrocarbon purification efficiency tends to decrease, which is not preferable. As a result, the pores can be binarized and a bimodal structure is obtained, so that high selectivity of the catalyst can be obtained. The pore diameter is preferably as large as possible within the range of particle diameter in order to enhance the bimodal structure.
[0041]
Firing at 1000 ° C in the atmosphererearSpecific surface area of 100m²/ G or more is used. Specific surface area is 100m²Since it tends to decrease the purification efficiency of hydrocarbons as it becomes smaller than / g, it is not preferable.
[0043]
  This configuration, SulfurDue to the repulsion between the yellow oxide and the composite oxide layer using at least two of silica, alumina, titania, zirconia, and zinc oxide, it is less susceptible to sulfur oxide poisoning and has excellent durability. Have.
[0044]
acidThe conductive oxide layer has a configuration of silica having silicon alkoxide as a precursor.
[0045]
  This configuration, SilicaBy using elemental alkoxide, a uniform silica coating layer can be formed on the support by a simple method called impregnation.
[0046]
Here, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraptoxysilane, tetrabutoxysilane, or the like is used as the silicon alkoxide.
[0047]
acidThe conductive oxide layer has a structure that is a composite oxide composed of silica having sodium silicate as a precursor and alumina having aluminum nitrate as a precursor.
[0048]
  This configuration, SilicaAn acidic oxide is formed using sodium acid and aluminum nitrate, and a uniform coating layer made of silica and alumina can be formed on the support by a simple method called impregnation.
[0049]
acidThe ratio of Al / (Si · Al) in the composite oxide composed of silica and alumina in the conductive oxide layer is 40-80.
[0050]
  This configuration, SulfurWhen the yellow oxide and the composite oxide are repelled by acidity, the sulfur oxide is less likely to approach the catalyst component and the carrier layer.
[0051]
Here, when the ratio of Al / (Si · Al) of the composite oxide composed of silica and alumina is smaller than 50, the repulsion between the sulfur oxide which is an acidic gas and the acidic oxide becomes insufficient, and the ratio is If it is greater than 70, the repulsive effect of sulfur oxides and acidic oxides will be saturated, which is not preferable. If the ratio is smaller than 40 and larger than 80, this tendency becomes remarkable, which is not preferable.
[0052]
acidThe conductive oxide layer has a structure that is a composite oxide composed of silica having sodium silicate as a precursor and titania having titanium chloride as a precursor.
[0053]
  This configuration,saltAn acidic oxide is formed using titanium fluoride and sodium silicate, and a uniform coating layer composed of silica and titania can be formed on the carrier by a simple method called an impregnation method.
[0054]
ShiThe composite oxide composed of Rica and titania has a Ti / (Si · Ti) ratio of 40 to 80.
[0055]
  This configuration, SulfurThe yellow oxide and the composite oxide repel each other with acidity, so that the sulfur oxide is less likely to approach the catalyst component and the carrier layer.
[0056]
Here, if the Ti / (Si · Ti) ratio of the composite oxide composed of silica and titania is smaller than 50, the repulsion between the sulfur oxide which is an acidic gas and the acidic oxide becomes insufficient, and the ratio is If it is greater than 70, the repulsive effect of sulfur oxides and acidic oxides will be saturated, which is not preferable. If the ratio is smaller than 40 and larger than 80, this tendency becomes remarkable, which is not preferable.
[0069]
acidThe carrier slurry coated with the conductive oxide has a viscosity of 1 cP to 300 cP.
[0070]
  This configuration, EasyA uniform coating layer can be formed on the substrate by a simple method, and the hydrocarbons in the exhaust gas can be efficiently purified.
[0071]
Here, the viscosity of the slurry is 1 cP to 300 cP, preferably 2 cP to 50 cP. As the viscosity is less than 2 cP, it is necessary to provide a number of steps for coating the support, which takes more time to manufacture, and as the viscosity becomes greater than 50 cP, the slurry enters and leaves the cell in the cell. Since it becomes difficult to form a uniform carrier film on the substrate, neither is preferable. This tendency becomes more significant as the viscosity becomes smaller than 1 cP and larger than 300 cP.
[0072]
  After impregnating the support in the solution of the precursor of the acidic oxide, primary firing is performed to coat the surface of the support with the acidic oxide layer.The firing temperature during primary firing is500 ° C to 1000 ° CIt has the composition which is.
[0073]
  This configuration,acidIt has the effect that the repulsive action between sulfur oxide and acidic oxide, which is a reactive gas, is good.
[0074]
Here, after impregnating the support in the solution of the precursor of the acid oxide, the firing temperature at the time of the primary firing becomes lower than 500 ° C., the acidity of the acidic oxide becomes weak and sufficient repulsion action cannot be obtained. In addition, as the temperature rises above 1000 ° C., the acidic oxide causes crystal growth (sintering) and closes the pores of the support, so that the specific surface area decreases and the catalytic activity decreases. Any of these is not preferable. This tendency becomes more significant as the firing temperature is lower than 400 ° C. and higher than 1100 ° C., which is not preferable.
[0077]
  Here, the firing temperature at the time of primary firing after impregnating the precursor of the composite oxide into the support is 400 ° C to 800 ° C, preferably 500 ° C to 700 ° C.With this configuration, the repulsive action between the sulfur oxide, which is an acidic gas, and the composite oxide is good, and deterioration due to the sulfur oxide can be prevented, so that the durability is improved.As the firing temperature becomes lower than 500 ° C., a tendency that the acidity of the composite oxide becomes weak and sufficient repelling action cannot be obtained is observed, and as the firing temperature becomes higher than 700 ° C., the composite oxide grows in crystal growth (sinter). (Ring) is caused to close the pores of the carrier, so that the specific surface area tends to decrease and the catalytic activity tends to decrease. This tendency becomes more significant as the firing temperature is lower than 400 ° C. and higher than 800 ° C., which is not preferable.
[0078]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0079]
(Embodiment 1)
1 is a cross-sectional view of an exhaust gas purifying material according to Embodiment 1 of the present invention.
[0080]
In FIG. 1, 1 is an exhaust gas purifying material of Embodiment 1, 2 is a substrate having a honeycomb structure, 3 is a carrier layer formed on the surface of the substrate 2, and 4 is an acidic oxide coated on the surface of the carrier layer 3. Layers 5 are catalyst components supported on the surface of the acidic oxide layer 4.
[0081]
About the exhaust gas purification material of Embodiment 1 comprised as mentioned above, the manufacturing method is demonstrated below.
[0082]
FIG. 2 is a flowchart of the manufacturing process of the exhaust gas purifying material according to the first embodiment.
[0083]
In FIG. 2, S1 is a step of coating the surface of the carrier with the acidic oxide layer 4, S2 is a step of coating the carrier layer 3 coated with the acidic oxide on the substrate 2 having a honeycomb structure, and S3 is a step on the substrate 2. The catalyst component 5 is supported on the surface of the carrier layer 3 coated with the acidic oxide layer 4.
[0084]
Hereinafter, each step will be described in detail.
[0085]
(1) Step of coating the surface of the carrier with the acidic oxide layer 4 (S1)
A predetermined amount of the precursor of the acidic oxide layer 4 is added to the solvent and stirred, and a predetermined amount of the carrier is added to the solution, stirred for a whole day and night, dried, and then fired at 500 ° C. to 1000 ° C. in the atmosphere.
[0086]
(2) Step of coating the substrate 2 having a honeycomb structure with the carrier layer 3 coated with the acidic oxide (S2)
Pure water and a dispersant are added to the carrier layer 3 coated with the acidic oxide to prepare a slurry. After the slurry is diluted to adjust the viscosity, the substrate 2 of the honeycomb structure is dipped and pulled up, and then the excess slurry is removed and dried. The above operation is repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0087]
(3) A step of supporting the catalyst component 5 on the surface of the carrier layer 3 coated with the acidic oxide layer 4 on the substrate 2 (S3).
After immersing the substrate 2 of the honeycomb structure coated with the carrier coated with the acidic oxide layer 4 in a solution obtained by adding a predetermined amount of the metal salt of the catalyst component 5 and an additive to pure water, and pulling up, Remove excess solution, dry and bake in air. Furthermore, the honeycomb structure coated with the carrier coated with the acidic oxide layer 4 is immersed in a solution obtained by adding a predetermined amount of the metal salt of the catalyst component 5 and an additive to pure water, and then the excess solution Is removed, dried, and fired in a reducing atmosphere to form the exhaust gas purifying material 1.
[0088]
Here, it is appropriate that the acidic oxide layer 4 is 6 wt% to 10 wt% with respect to the carrier layer 3, the thickness of the acidic oxide layer 4 is 0.1 μm to 20 μm, and the coverage is 80% to 100%. It is. The carrier coated with the acidic oxide layer 4 is suitably 7 wt% to 15 wt% with respect to the base material 2. Further, the carrier of the carrier layer 3 has an average particle diameter of 1 μm to 10 μm, N₂In the pore distribution measurement by the adsorption method, when the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume, and further when calcined at 1000 ° C. in the atmosphere. Specific surface area is 100m²It is appropriate that the heat resistant inorganic oxide is not less than / g.
[0089]
In the method for producing the exhaust gas purifying material 1, the slurry has a viscosity of 1 cP to 300 cP, preferably 2 cP to 50 cP. Further, the firing temperature at the time of primary firing after impregnating the support in the acidic oxide precursor solution is suitably 500 ° C to 1000 ° C.
[0090]
The carrier layer 3 provides a high specific surface area by coating the surface of the substrate 2, and is composed of inorganic oxides such as alumina, silica, titania and zirconia, and composite inorganic oxides such as silica and alumina. The
[0091]
The acidic oxide layer 4 suppresses the reaction between the sulfur oxide in the exhaust gas and the support layer 3 or the catalyst component 5, and is composed of an inorganic oxide or a composite inorganic oxide having a higher acidity than the support. .
[0092]
The catalyst component 5 purifies harmful components in the exhaust gas, and is composed of noble metals such as Pt and Pd, non-metals such as Co, Ni, and Cu, or oxides thereof.
[0093]
In the step S1 of coating the surface of the carrier with the acidic oxide layer 4, the acidic oxide is uniformly coated on the surface of the carrier, and the reaction between the sulfur oxide in the exhaust gas and the carrier layer 3 or the catalyst component 5 is effectively suppressed. Is done.
[0094]
Further, a step S2 of coating the carrier layer 3 coated with the acidic oxide on the substrate 2 having a honeycomb structure, and a step of supporting the catalyst component 5 on the surface of the carrier layer 3 coated with the acidic oxide on the substrate 2 In S3, harmful components in the exhaust gas are purified.
[0095]
(Embodiment 2)
The exhaust gas purifying material of Embodiment 2 is the same as that of Embodiment 1 except that the support is activated alumina, the acidic oxide is silica, and the silica precursor is silicon alkoxide. In addition, about the thing similar to FIG. 1, FIG. 2 in Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0096]
The carrier layer 3 provides a high specific surface area by coating the surface of the substrate 2.
[0097]
The acidic oxide layer 4 suppresses the reaction between the sulfur oxide in the exhaust gas and the carrier layer 3 or the catalyst component 5.
[0098]
Here, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraptoxysilane, tetrabutoxysilane, or the like is used as the silicon alkoxide.
[0099]
FIG. 3 is a flowchart of the manufacturing process of the exhaust gas purifying material according to the second embodiment.
[0100]
In FIG. 3, S4 is a step of coating the surface of activated alumina (support) with an acidic oxide layer 4, and S5 is a substrate 2 having a honeycomb structure of activated alumina (support layer 3) coated with silica (acidic oxide). Step S6 is a step of supporting the catalyst component 5 on the surface of the activated alumina (support layer 3) coated with silica (acidic oxide) on the substrate 2.
[0101]
In step S4 for coating the surface of the carrier with the acidic oxide layer 4, silica (acidic oxide) is uniformly coated on the surface of the activated alumina (carrier layer 3), and the sulfur oxide in the exhaust gas and the carrier layer 3 or catalyst component The reaction with 5 is effectively suppressed.
[0102]
Further, the step S2 of coating the activated alumina (carrier layer 3) coated with silica (acidic oxide) on the substrate 2 having a honeycomb structure, and the surface of the carrier layer 3 coated with the acidic oxide on the substrate 2 are applied. In step S3 for supporting the catalyst component 5, harmful components in the exhaust gas are purified.
[0103]
(Embodiment 3)
The exhaust gas purification material of Embodiment 3 is implemented except that the support is activated alumina, and the acidic oxide is a composite oxide formed using at least two of silica, alumina, titania, zirconia, and zinc oxide. This is the same as the first embodiment. In addition, about the thing similar to FIGS. 1-3 in Embodiment 1, 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0104]
The carrier layer 3 provides a high specific surface area by coating the surface of the substrate 2.
[0105]
The acidic oxide layer 4 suppresses the reaction between the sulfur oxide in the exhaust gas and the support layer 3 or the catalyst component 5, and is formed using at least two or more of silica, alumina, titania, zirconia, and zinc oxide. It is comprised with the complex oxide made. Here, a composite oxide composed of silica and alumina is used, but a composite oxide composed of silica and titania, zirconia and alumina, zinc oxide and titania, or the like is used.
[0106]
The catalyst component 5 purifies harmful components in the exhaust gas, and is composed of noble metals such as Pt and Pd, non-metals such as Co, Ni, and Cu, or oxides thereof.
[0107]
(Embodiment 4)
FIG. 4 is a cross-sectional view of an exhaust gas purifying material according to Embodiment 4 of the present invention.
[0108]
In FIG. 4, 21 is an exhaust gas purifying material of Embodiment 4, 22 is a substrate having a honeycomb structure, 23 is an alumina layer formed on the surface of the substrate 22, 24 is silica and alumina coated on the surface of the alumina layer 23 A composite oxide layer 25 is a catalyst component supported on the surface of the composite oxide layer 24 made of silica and alumina.
[0109]
About the exhaust gas purification material of Embodiment 4 comprised as mentioned above, the manufacturing method is demonstrated below.
[0110]
FIG. 5 is a flowchart of the manufacturing process of the exhaust gas purifying material according to the fourth embodiment.
[0111]
In FIG. 5, S7 is a step of coating the surface of the alumina layer 23 with a composite oxide layer 24 made of silica and alumina, and S8 is a structure in which the alumina layer 23 covered with the composite oxide layer 24 made of silica and alumina has a honeycomb structure. The step of coating the base material 22, S 9 is the step of supporting the catalyst component 25 on the surface of the alumina layer 23 coated with the composite oxide layer 24 composed of silica and alumina on the base material 22.
[0112]
Hereinafter, each step will be described in detail.
[0113]
(1) A step of coating the surface of the alumina layer 23 with the composite oxide layer 24 made of silica and alumina (S7)
A predetermined amount of a metal salt, which is a starting material for alumina, is added to a solvent and stirred and dissolved. Next, a metal salt solution that is a starting material of silica is added and stirred. Thereafter, it is sufficiently washed, dried, and fired at 400 ° C. to 800 ° C. in the air.
[0114]
(2) A step of coating the substrate 22 having a honeycomb structure with the alumina layer 23 coated with the composite oxide layer 24 made of silica and alumina (S8).
Pure water and a dispersant are added to the alumina layer 23 coated with the composite oxide layer 24 made of silica and alumina to prepare a slurry. After the slurry is diluted to adjust the viscosity, the substrate 22 of the honeycomb structure is dipped and pulled up, and then the excess slurry is removed and dried. The above operation is repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0115]
(3) A step of supporting the catalyst component 25 on the surface of the alumina layer 23 coated with the composite oxide layer 24 composed of silica and alumina on the substrate 22 (S9).
A substrate 22 having a honeycomb structure coated with an alumina layer 23 coated with a composite oxide layer 24 made of silica and alumina was dipped in a solution containing a predetermined amount of a metal salt of catalyst component 25 and an additive and pulled up. Thereafter, excess solution is removed, freeze-dried, and fired to obtain the exhaust gas purifying material 21.
[0116]
Here, the ratio of Al / (Si · Al) of the composite oxide layer 24 made of silica and alumina is 50 to 70, and the film thickness of the composite oxide layer 24 made of silica and alumina is 0.1 μm to 20 μm, The coverage is suitably 80% to 100%. The alumina layer 23 coated with the composite oxide layer 24 made of silica and alumina is suitably 7 wt% to 15 wt% with respect to the base material 22. Furthermore, the carrier of the alumina layer 23 has an average particle diameter of 1 μm to 10 μm, N₂In the pore distribution measurement by the adsorption method, the total pore volume was 0.3 ml / g or more, and the pore volume having a pore diameter of 100 mm or more was burned at 60% or more of the total pore volume, and further at 1000 ° C. in the atmosphere. Specific surface area of 100m²It is appropriate that the heat resistant inorganic oxide is not less than / g.
[0117]
In the method for producing an exhaust gas purifying material, the viscosity of the slurry is suitably 1 cP to 300 cP, preferably 2 cP to 50 cP. Further, the temperature at which primary firing is carried out after coating the composite oxide layer 24 composed of silica and alumina on the alumina layer 23 is 400 ° C. to 800 ° C., preferably 500 ° C. to 700 ° C.
[0118]
The alumina layer 23 provides a high specific surface area by coating the surface of the substrate 22. The composite oxide layer 24 made of silica and alumina is for suppressing the reaction between the sulfur oxide in the exhaust gas and the alumina layer 23 or the catalyst component 25.
[0119]
The catalyst component 25 purifies harmful components in the exhaust gas, and is composed of noble metals such as Pt and Pd, non-metals such as Co, Ni, and Cu, or oxides thereof.
[0120]
In the step S7 of coating the surface of the alumina layer 23 with the composite oxide layer 24 made of silica and alumina, the surface of the alumina layer 23 is uniformly coated with the composite oxide layer 24 made of silica and alumina, and the sulfur oxide in the exhaust gas And the alumina layer 23 or the catalyst component 25 are effectively suppressed.
[0121]
Step S8 for coating the substrate 22 having a honeycomb structure with the alumina layer 23 coated with the composite oxide layer 24 composed of silica and alumina, and alumina coated with the composite oxide layer 24 composed of silica and alumina on the substrate 22 In step S9 of supporting the catalyst component 25 on the surface of the layer 23, harmful components in the exhaust gas are purified.
[0122]
(Embodiment 5)
FIG. 6 is a cross-sectional view of an exhaust gas purifying material according to Embodiment 5 of the present invention.
[0123]
In FIG. 6, 30 is an exhaust gas purifying material according to the fifth embodiment, 31 is a substrate having a honeycomb structure, 32 is an alumina layer formed on the surface of the substrate 31, 33 is titania and silica coated on the surface of the alumina layer 32 The composite oxide layer 34 is a catalyst component supported on the surface of the composite oxide layer 33 made of titania and silica.
[0124]
About the exhaust gas purification material of Embodiment 5 comprised as mentioned above, the manufacturing method is demonstrated below.
[0125]
FIG. 7 is a flowchart of the method of manufacturing the exhaust gas purifying material according to the fifth embodiment.
[0126]
In FIG. 7, S10 is a step of coating the surface of the alumina layer 32 with a composite oxide layer 33 made of silica and titania, and S11 has a honeycomb structure with the alumina layer 32 covered with a composite oxide layer 33 made of silica and titania. The step of coating the substrate 31, S 12 is a step of supporting the catalyst component 34 on the surface of the alumina layer 32 coated with the composite oxide layer 33 composed of silica and titania on the substrate 31.
[0127]
Hereinafter, each step will be described in detail.
[0128]
(1) A step of coating the surface of the alumina layer 32 with the composite oxide layer 33 made of silica and titania (S10)
A predetermined amount of a metal salt which is a starting material of titania is added to a solvent and stirred and dissolved, and then a predetermined amount of alumina is added and further stirred. Next, a metal salt solution that is a starting material of silica is added and stirred. Thereafter, it is sufficiently washed, dried, and fired at 400 ° C. to 800 ° C. in the air.
[0129]
(2) A step of coating the substrate 31 having a honeycomb structure with the alumina layer 32 coated with the composite oxide layer 33 made of silica and titania (S11).
Pure water and a dispersant are added to the alumina layer 32 covered with the composite oxide layer 33 made of silica and titania to prepare a slurry. After the slurry is diluted to adjust the viscosity, the substrate 31 of the honeycomb structure is dipped and pulled up, and then the excess slurry is removed and dried. The above operation is repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0130]
(3) A step of supporting the catalyst component 34 on the surface of the alumina layer 32 coated with the composite oxide layer 33 made of silica and titania on the base material 31 (S12).
A substrate 31 having a honeycomb structure coated with an alumina layer 32 coated with a composite oxide layer 33 made of silica and titania was dipped in a solution containing a predetermined amount of a metal salt of catalyst component 34 and an additive, and pulled up. Thereafter, the excess solution is removed, freeze-dried, and fired to obtain the exhaust gas purification material 30.
[0131]
Here, the ratio of Ti / (Si · Ti) of the composite oxide layer 33 made of silica and titania is 50 to 70, and the thickness of the composite oxide layer 33 made of silica and titania is 0.1 μm to 20 μm, The coverage is suitably 80% to 100%. The alumina layer 32 covered with the composite oxide layer 33 made of silica and titania is suitably 7 wt% to 15 wt% with respect to the base material 31. Furthermore, the carrier of the alumina layer 32 has an average particle diameter of 1 μm to 10 μm, N₂In the pore distribution measurement by the adsorption method, the total pore volume was 0.3 ml / g or more, and the pore volume having a pore diameter of 100 mm or more was burned at 60% or more of the total pore volume, and further at 1000 ° C. in the atmosphere. Specific surface area of 100m²It is appropriate that the heat resistant inorganic oxide is not less than / g.
[0132]
In the method for producing an exhaust gas purifying material, the viscosity of the slurry is suitably 1 cP to 300 cP, preferably 2 cP to 50 cP. Further, the temperature at which primary firing is performed after coating the composite oxide layer 33 made of silica and titania on the alumina layer 32 is 400 ° C. to 800 ° C., preferably 500 ° C. to 700 ° C.
[0133]
The alumina layer 32 provides a high specific surface area by coating the surface of the substrate 31.
[0134]
The composite oxide layer 33 made of silica and titania is for suppressing the reaction between the sulfur oxide in the exhaust gas and the alumina layer 32 or the catalyst component 34.
[0135]
The catalyst component 34 purifies harmful components in the exhaust gas, and is composed of a noble metal such as Pt or Pd, a non-metal such as Co, Ni or Cu, or an oxide thereof.
[0136]
In step S10 for coating the surface of the alumina layer 32 with the composite oxide layer 33 made of silica and titania, the surface of the alumina layer 32 is uniformly coated with the composite oxide layer 33 made of silica and titania, and the sulfur oxide in the exhaust gas The reaction between the alumina layer 32 and the catalyst component 34 is effectively suppressed.
[0137]
Step S11 of coating the substrate 31 having a honeycomb structure with the alumina layer 32 coated with the composite oxide layer 33 made of silica and titania, and alumina coated with the composite oxide layer 33 made of silica and titania on the substrate 31 In step S12 in which the catalyst component 34 is supported on the surface of the layer 32, harmful components in the exhaust gas are purified.
[0138]
【Example】
Hereinafter, specific examples of the present invention will be described in detail.
[0139]
Example 1
(1) A step of coating a silica layer on the surface of activated alumina
A predetermined amount of tetraethoxysilane (manufactured by Wako Pure Chemical Industries) is added to 5 L of absolute ethanol (manufactured by Wako Pure Chemical Industries) and stirred, 1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) is added and stirred for a whole day and then dried. And was fired at 900 ° C. in the air.
[0140]
(2) A process of coating activated alumina coated with silica on a substrate having a honeycomb structure
1800 g of activated alumina coated with silica was added to a mixed solution obtained by adding 720 g of a dispersant (trade name Poise, manufactured by Kao Corporation) to 2.5 L of pure water, and mixed for 20 hours to prepare a slurry. This slurry is diluted with a solution having the same concentration as the above mixed solution so that the powder concentration of the slurry becomes 1/3, and the diluted slurry has a diameter of 5.66 inches, a length of 6 inches, and the number of cells of 400 cells / in.²The cordierite honeycomb structure (manufactured by NGK) was dipped, pulled up, excess slurry was removed by air blow, and then dried at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0141]
(3) A step of supporting a catalyst component on the surface of activated alumina coated with silica on a substrate.
After immersing the honeycomb structure in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water and pulling it up, the excess solution is removed by air blowing and then dried by freeze-drying. Baked at 600 ° C.
[0142]
Furthermore, after immersing and lifting the honeycomb structure carrying palladium in a solution obtained by dissolving a predetermined amount of dinitrodiaminoplatinum nitric acid solution and citric acid in 5 L of pure water, the excess solution was removed by air blowing, It dried by the freeze-drying method and baked at 600 degreeC in the reducing atmosphere.
[0143]
(Example 2)
1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) is added to a predetermined amount of 0.4 mol sodium silicate (manufactured by Wako Pure Chemical Industries) and stirred for 2 hours, and then a predetermined amount of 0.4 mol aluminum nitrate aqueous solution is added and further 2 Stir for hours. After thoroughly washing with 5 L of pure water, suction filtration was performed, followed by drying at 100 ° C., followed by firing at 900 ° C. in the atmosphere.
[0144]
Thereafter, an exhaust gas purifying material was produced in the same manner as in Example 1.
[0145]
(Example 3)
1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) is added to a predetermined amount of 0.4 mol sodium silicate (manufactured by Wako Pure Chemical Industries) and stirred for 2 hours, and then a predetermined amount of 0.4 mol titanium tetrachloride aqueous solution is added. Stir for 2 hours. After thoroughly washing with 5 L of pure water, suction filtration was performed, followed by drying at 100 ° C., followed by firing at 900 ° C. in the atmosphere.
[0146]
Thereafter, an exhaust gas purifying material was produced in the same manner as in Example 1.
[0147]
(Example 4)
(1) The process of coating the surface of activated alumina with a composite oxide layer composed of silica and alumina
A predetermined amount of aluminum nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 5 L of pure water, stirred and dissolved, and then 1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) was added and stirred for 2 hours. Next, a predetermined amount of a mixed solution of an aqueous sodium silicate solution and an aqueous sodium hydroxide solution is added to the activated alumina-containing solution all at once, and the mixture is further stirred for 2 hours, thoroughly washed by decantation, dried and dried in the atmosphere. Baked at 600 ° C.
[0148]
(2) A step of coating a substrate having a honeycomb structure with activated alumina coated with a composite oxide layer composed of silica and alumina.
1800 g of activated alumina coated with a composite oxide composed of silica and alumina was added to a mixed solution obtained by adding 720 g of a dispersant (trade name Poise, manufactured by Kao Corporation) to 2.5 L of pure water, and mixed for 20 hours to prepare a slurry. . This slurry is diluted with a solution having the same concentration as the above mixed solution so that the powder concentration of the slurry becomes 1/3, and the diluted slurry has a diameter of 5.66 inches, a length of 6 inches, and the number of cells of 400 cells / in.²The cordierite honeycomb structure (manufactured by NGK) was dipped and pulled up, and then excess slurry was removed by air blowing, followed by drying at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0149]
(3) A step of supporting a catalyst component on the surface of activated alumina coated with a composite oxide composed of silica and alumina on a substrate.
A honeycomb structure coated with alumina coated with a composite oxide consisting of silica and alumina is immersed in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water, and after lifting, the excess solution is air blown. After being removed by the above, it was dried by freeze-drying and baked at 600 ° C. in the atmosphere.
[0150]
Further, a honeycomb structure coated with alumina coated with a composite oxide composed of silica and alumina carrying palladium is immersed in a predetermined amount of dinitrodiaminoplatinum nitric acid solution and citric acid dissolved in 5 L of pure water, After pulling up, the excess solution was removed by air blowing, dried by freeze drying, and baked at 600 ° C. in a reducing atmosphere.
[0151]
(Example 5)
(1) A step of coating the surface of activated alumina with a composite oxide layer composed of silica and titania
A predetermined amount of titanium chloride solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 5 L of pure water, stirred and dissolved, and then 1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) was added and stirred for 2 hours. Next, a predetermined amount of an aqueous sodium silicate solution was added to the activated alumina-containing solution all at once, and the mixture was further stirred for 2 hours, thoroughly washed by decantation, dried, and fired at 600 ° C. in the atmosphere.
[0152]
(2) A step of coating a substrate having a honeycomb structure with activated alumina coated with a composite oxide layer composed of silica and titania.
1800 g of activated alumina coated with a composite oxide composed of silica and titania was added to a mixed solution obtained by adding 720 g of a dispersant (trade name Poise, manufactured by Kao Corporation) to 2.5 L of pure water, and mixed for 20 hours to prepare a slurry. . This slurry is diluted with a solution having the same concentration as the above mixed solution so that the powder concentration of the slurry becomes 1/3, and the diluted slurry has a diameter of 5.66 inches, a length of 6 inches, and the number of cells of 400 cells / in.²The cordierite honeycomb structure (manufactured by NGK) was dipped and pulled up, and then excess slurry was removed by air blowing, followed by drying at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0153]
(3) A step of supporting a catalyst component on the surface of activated alumina coated with a composite oxide composed of silica and titania on a substrate.
A honeycomb structure coated with alumina coated with a composite oxide consisting of silica and titania is immersed in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water, and after lifting, the excess solution is air blown. After being removed by the above, it was dried by freeze-drying and baked at 600 ° C. in the atmosphere.
[0154]
Further, a honeycomb structure coated with alumina coated with a composite oxide composed of silica and titania supporting palladium is immersed in a solution of a predetermined amount of dinitrodiaminoplatinum nitrate solution and citric acid dissolved in 5 L of pure water, After pulling up, the excess solution was removed by air blowing, dried by freeze drying, and baked at 600 ° C. in a reducing atmosphere.
[0155]
(Comparative Example 1)
1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd., trade name TA series) was added to a mixed solution obtained by adding 720 g of a dispersant (made by Kao, trade name Poise) to 2.5 L of pure water, and mixed for 20 hours to prepare a slurry. . This slurry is diluted with a solution having the same concentration as the above mixed solution so that the powder concentration of the slurry becomes 1/3, and the diluted slurry has a diameter of 5.66 inches, a length of 6 inches, and the number of cells of 400 cells / in.²The cordierite honeycomb structure (manufactured by NGK) was dipped and pulled up, and then excess slurry was removed by air blowing, followed by drying at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0156]
Then, after immersing the honeycomb structure in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water and pulling it up, the excess solution is removed by air blowing, and then dried by freeze drying, Firing was performed at 600 ° C. in the air.
[0157]
Furthermore, after immersing and lifting the honeycomb structure carrying palladium in a solution obtained by dissolving a predetermined amount of dinitrodiaminoplatinum nitric acid solution and citric acid in 5 L of pure water, the excess solution was removed by air blowing, It dried by the freeze-drying method and baked at 600 degreeC in the reducing atmosphere.
[0158]
(Comparative Example 2)
1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd., trade name TA series) was added to a mixed solution obtained by adding 720 g of a dispersant (made by Kao, trade name Poise) to 2.5 L of pure water, and mixed for 20 hours to prepare a slurry. . This slurry is diluted with a solution having the same concentration as the above mixed solution so that the powder concentration of the slurry becomes 1/3, and the diluted slurry has a diameter of 5.66 inches, a length of 6 inches, and the number of cells of 400 cells / in.²The cordierite honeycomb structure (manufactured by NGK) was dipped and pulled up, and then excess slurry was removed by air blowing, followed by drying at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0159]
Then, after immersing the honeycomb structure in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water and pulling it up, the excess solution is removed by air blowing, and then dried by freeze drying, Firing was performed at 600 ° C. in the air.
[0160]
Furthermore, after immersing and lifting the honeycomb structure carrying palladium in a solution obtained by dissolving a predetermined amount of dinitrodiaminoplatinum nitric acid solution and citric acid in 5 L of pure water, the excess solution was removed by air blowing, It dried by the freeze-drying method and baked at 600 degreeC in the reducing atmosphere.
[0161]
Further, a predetermined amount of tetraethoxysilane (manufactured by Wako Pure Chemical Industries) was added to 5 L of absolute ethanol (manufactured by Wako Pure Chemical Industries) and stirred, impregnated with a honeycomb structure supporting palladium and platinum, dried, and then air Baked at 900 ° C.
[0162]
(Comparative Example 3)
A predetermined amount of sodium silicate (manufactured by Wako Pure Chemical Industries) and sodium hydroxide (manufactured by Wako Pure Chemical Industries) were added to 5 L of pure water, stirred and dissolved, and then 1800 g of activated alumina (manufactured by Sumitomo Chemical) was added. Stir for 2 hours. Next, a predetermined amount of an aqueous solution of aluminum nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) is added to the activated alumina-containing solution all at once, and the mixture is further stirred for 2 hours, sufficiently washed by decantation, dried, and dried in the atmosphere. Baked at 600 ° C. Thereafter, an exhaust gas purifying material was produced in the same manner as in Example 1.
[0163]
(Comparative Example 4)
A predetermined amount of sodium silicate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 5 L of pure water and stirred and dissolved. Then, 1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) was added and stirred for 2 hours. Next, a predetermined amount of an aqueous solution of titanium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) is added to the activated alumina-containing solution all at once, followed by further stirring for 2 hours, and after sufficient washing by decantation, drying is performed in the atmosphere. Baked at 600 ° C. Thereafter, an exhaust gas purifying material was produced in the same manner as in Example 1.
[0164]
(Comparative Example 5)
A predetermined amount of aluminum nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 5 L of pure water and stirred and dissolved. Then, 1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) was added and stirred for 2 hours. Next, a predetermined amount of a mixed solution of an aqueous sodium silicate solution and an aqueous sodium hydroxide solution is added to the activated alumina-containing solution all at once, and further stirred for 2 hours, sufficiently washed by decantation, dried, and dried in the atmosphere. And calcined at 600 ° C.
[0165]
Thereafter, 1800 g of activated alumina coated with a composite oxide composed of silica and alumina is added to a mixed solution obtained by adding 720 g of a dispersant (trade name, Poise made by Kao) to 2.5 L of pure water, and the slurry is mixed for 20 hours. Produced. This slurry is diluted with a solution having the same concentration as the mixed solution of pure water and a dispersant so that the powder concentration of the slurry becomes 1/3. The diameter is 5.66 inches, the length is 6 inches, and the number of cells is 400. Cell / in²The cordierite honeycomb structure (manufactured by NGK) was dipped and pulled up, and then excess slurry was removed by air blowing, followed by drying at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0166]
Next, a honeycomb structure coated with alumina coated with a composite oxide composed of silica and alumina is immersed in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water. After removing by air blowing, the film was dried overnight in a dryer at 100 ° C. and baked at 600 ° C. in the atmosphere.
[0167]
Further, a honeycomb structure coated with alumina coated with a composite oxide composed of silica and alumina carrying palladium is immersed in a solution obtained by adding a predetermined amount of dinitrodiaminoplatinum nitrate solution and citric acid to 5 L of pure water. After pulling up, the excess solution was removed by air blow, dried in a dryer at 100 ° C. overnight, and fired at 600 ° C. in a reducing atmosphere.
[0168]
(Comparative Example 6)
A predetermined amount of titanium chloride solution (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 5 L of pure water and stirred and dissolved, and then 1800 g of activated alumina (manufactured by Sumitomo Chemical Co., Ltd.) is added and stirred for 2 hours. Next, a predetermined amount of an aqueous sodium silicate solution was added to the activated alumina-containing solution all at once, and after further stirring for 2 hours, after sufficient washing by decantation, it was dried and fired at 600 ° C. in the atmosphere.
[0169]
Thereafter, 1800 g of activated alumina coated with a composite oxide composed of silica and alumina is added to a mixed solution obtained by adding 720 g of a dispersant (trade name, Poise, manufactured by Kao Corporation) to 2.5 L of pure water, and mixed for 20 hours. Was made. This slurry is diluted with a solution having the same concentration as the mixed solution of pure water and a dispersant so that the powder concentration of the slurry becomes 1/3. The diameter is 5.66 inches, the length is 6 inches, and the number of cells is 400. Cell / in²The cordierite honeycomb structure (manufactured by NGK) was dipped and pulled up, and then excess slurry was removed by air blowing, followed by drying at 300 ° C. The above operation was repeated several times to coat a predetermined amount, and then fired at a predetermined temperature in the atmosphere.
[0170]
Next, a honeycomb structure coated with alumina coated with a composite oxide composed of silica and titania is immersed in a solution obtained by adding a predetermined amount of palladium nitrate and citric acid to 5 L of pure water, and then an excess solution Was removed by air blow, dried overnight in a dryer at 100 ° C., and fired at 600 ° C. in the atmosphere.
[0171]
Further, a honeycomb structure coated with alumina coated with a composite oxide composed of silica and titania supporting palladium is immersed in a solution obtained by adding a predetermined amount of dinitrodiaminoplatinum nitrate solution and citric acid to 5 L of pure water. After pulling up, the excess solution was removed by air blow, dried in a dryer at 100 ° C. overnight, and fired at 600 ° C. in a reducing atmosphere.
[0172]
Hereinafter, for the exhaust gas purifying materials manufactured in Examples 1 to 5 and Comparative Examples 1 to 6, a catalytic activity evaluation test and SO₂An oxidation ability evaluation test was conducted.
[0173]
Here, the fixed bed flow system reactor for conducting the catalytic activity evaluation test will be described.
[0174]
FIG. 8 is a schematic view of the fixed bed flow system reactor used in the catalytic activity evaluation test.
[0175]
In FIG. 8, 40 is a fixed bed flow system reactor, 41 and 42 are gas flow controllers, 43 is a liquid flow controller, 44 is a vaporizer, 45 is a quartz tube, 46 is an electric furnace, and 47 is quartz wool. 48 is an exhaust gas purifying material, 49 is NDIR CO, CO₂A gas analyzer 50 is a gas chromatograph.
[0176]
A catalyst activity evaluation test method performed using the fixed bed flow system reactor 40 configured as described above will be described.
[0177]
After adjusting the nitrogen gas and the dried atmosphere to a predetermined flow rate by the gas flow rate regulator 42 and the hydrocarbon flow rate by the liquid flow rate regulator 43, the hydrocarbon is vaporized at a predetermined concentration by the vaporizer 44, Mix nitrogen gas and dry air. The mixed gas is introduced into the quartz tube 45 and purified by the exhaust gas purifying material 48 placed in the quartz tube 45. Here, the exhaust gas purifying material 48 subjected to the test was cut into a predetermined dimension so that it could be evaluated in the reaction system. In addition, quartz wool 47 is disposed before and after the exhaust gas purifying material 48, and the quartz tube 45 is installed in an electric furnace 46. After that, some of the purified mixed gas is NDIR CO, CO₂It is introduced into the gas analyzer 49 and detects the concentration of carbon monoxide and carbon dioxide.
[0178]
Here, the catalytic activity evaluation test is performed with an oxygen partial pressure of 4% and a space velocity of 30000 h.^-1The change in catalyst activity with time was measured under conditions of a hydrocarbon concentration of 350 ppm and an electric furnace 46 temperature of 250 ° C.
[0179]
Thus, the oxidation rate was calculated from (Equation 1) from the measured carbon monoxide concentration and carbon dioxide concentration.
[0180]
[Expression 1]

[0181]
In (Equation 1), PCO is the NDIR carbon monoxide, carbon monoxide concentration value measured by a carbon dioxide gas analyzer, PCO₂Is the value of carbon dioxide concentration measured by NDIR carbon monoxide and carbon dioxide gas analyzer, PC is the CO when 100% of hydrocarbons burn₂It is a theoretical value of concentration.
[0182]
On the other hand, the other part of the purified mixed gas is introduced into the gas chromatograph 50 through the gas sampling device, and each component of the unreacted hydrocarbon is quantified. The decomposition rate associated with the reaction is determined in advance with the exhaust gas purifying material 48 not disposed, and the hydrocarbon components are determined in advance. The value at this time is defined as 100%, and the unreacted carbonization contained in the purified mixed gas. It calculated from the residual rate of hydrogen.
[0183]
Next, SO₂The oxidation ability evaluation test will be described.
[0184]
Figure 9 shows SO₂It is the schematic of the reaction apparatus used for the oxidation ability evaluation test.
[0185]
In FIG. 9, 51 is SO.₂Reactors for performing an oxidative evaluation test, 52, 53 and 54 are gas flow controllers, 55 is a gas mixer, 56 is a quartz tube, 57 is an electric furnace, 58 is quartz wool, 59 is an exhaust gas purification material, and 60 is NDIR SO₂It is a gas analyzer.
[0186]
SO performed using the reactor configured as described above.₂The oxidation ability evaluation test method will be described.
[0187]
Nitrogen gas whose flow rate is adjusted by gas flow regulators 52, 53, 54, dry air, SO₂Gas (SO₂(Concentration = 1000 ppm, balance gas = nitrogen) are mixed in the mixer 55, introduced into the quartz tube 56, and reacted by the exhaust gas purifying material 59 placed in the quartz tube 56. Here, the exhaust gas purifying material 59 to be used for the test was cut into a predetermined size so that it could be evaluated in the reaction system. Further, quartz wool 58 is disposed before and after the exhaust gas purifying material 59, and the quartz tube 56 is installed in an electric furnace 57. After that, the reacted gas is NDIR type SO.₂Introduced to gas analyzer 60 and SO₂Measure the concentration.
[0188]
Where SO₂Oxidation capacity evaluation test was performed with an oxygen partial pressure of 8% and a space velocity of 30000h.^-1, SO₂The test was carried out under conditions of a concentration of 100 ppm and a temperature in the electric furnace 57 of 400 ° C., and a change in the catalyst activity with time was measured.
[0189]
SO₂Oxidizing capacity is determined by SO before being introduced into the quartz tube 56.₂Concentration and SO₂SO measured by analyzer₂The concentration was evaluated.
[0190]
In (Table 1) to (Table 17), the catalyst activity evaluation test and SO in the exhaust gas purifying material 59 produced in Examples 1 to 5 and Comparative Examples 1 to 6 are shown.₂The result of an oxidation ability evaluation test is shown.
[0191]
Table 1 shows the average particle diameter (μm) of activated alumina as a carrier, N₂Total pore volume (ml / g) in pore distribution measurement by adsorption method, presence rate of pore volume with pore diameter of 100 mm or more (%), specific surface area after firing at 1000 ° C. in the atmosphere (m²/ G) and the hydrocarbon purification rate (%) at 250 ° C.
[0192]
[Table 1]

[0193]
As apparent from (Table 1), the average particle diameter of the activated alumina is 1 μm to 10 μm, N₂In the pore distribution measurement by the adsorption method, the total pore volume is 0.3 ml / g or more, the abundance of pore volumes having a pore diameter of 100 mm or more is 60% or more, and the specific surface area after firing at 1000 ° C. in the atmosphere is 100 m.²/ G or more, the purification rate of hydrocarbons was 80% or more. On the other hand, when activated alumina outside the above range was used, the hydrocarbon purification rate was 40% to 60%. Thus, it was found that when activated alumina in the above range was used, a highly active exhaust gas purification material was obtained.
[0194]
Table 2 shows the relationship between the coating amount (wt%) on the carrier base material and the hydrocarbon purification rate (%) at 250 ° C.
[0195]
[Table 2]

[0196]
As is clear from this (Table 2), when the carrier coated with the acidic oxide on the substrate is 7 wt% to 15 wt%, the hydrocarbon purification rate is 85%, and the coverage outside the above range is 45% to It was found that the purification rate of hydrocarbons was higher than that of 60%.
[0197]
Table 3 shows the relationship between the coating amount (wt%) of the composite oxide composed of silica and alumina on the base material and the hydrocarbon purification rate (%) at 250 ° C.
[0198]
[Table 3]

[0199]
As apparent from this (Table 3), the coating amount of the composite oxide composed of silica and alumina with respect to alumina is 7 wt% to 15 wt%, and the hydrocarbon purification rate is as high as 95% to 96%, which is outside the above range. It is clear that the coating amount is as low as 48% to 60%.
[0200]
Next, (Table 4) shows the relationship between the coating amount (wt%) of the composite oxide composed of silica and titania on the base material and the hydrocarbon purification rate (%) at 250 ° C.
[0201]
[Table 4]

[0202]
As is clear from this (Table 4), the coating amount of the composite oxide composed of silica and titania on alumina is 7 wt% to 15 wt%, and the hydrocarbon purification rate is as high as 93% to 95%, which is outside the above range. It is clear that the coating amount is as low as 50% to 59%.
[0203]
Next, (Table 5) shows the relationship between the viscosity (cP) of the slurry of the carrier coated with the acidic oxide and the hydrocarbon purification rate (%) at 250 ° C.
[0204]
[Table 5]

[0205]
As is clear from this (Table 5), in the method for producing an exhaust gas purifying material, the viscosity of the carrier slurry coated with acidic oxide is 1 cP to 300 cP, and the hydrocarbon purification rate is 70% to 85%, It has been found that the purification rate of hydrocarbons is high as compared with 50% to 55% of the viscosity of the slurry outside the range.
[0206]
Next, (Table 6) shows the relationship between the viscosity (cP) of the slurry of the carrier coated with the composite oxide composed of silica and alumina and the hydrocarbon purification rate (%) at 250 ° C.
[0207]
[Table 6]

[0208]
As is clear from this (Table 6), when the viscosity of the slurry of the carrier coated with the composite oxide composed of silica and alumina is 1 cP to 300 cP, the purification rate of hydrocarbon is 70% to 96%, and is outside the above range. It was found that the purification rate of hydrocarbons was higher than that of 53% to 54% of the viscosity of the slurry.
[0209]
Table 7 shows the relationship between the viscosity (cP) of the support slurry coated with the composite oxide composed of silica and titania and the hydrocarbon purification rate (%) at 250 ° C.
[0210]
[Table 7]

[0211]
As is clear from this (Table 7), when the viscosity of the slurry of the carrier coated with the composite oxide composed of silica and titania is 1 cP to 300 cP, the hydrocarbon purification rate is 82% to 96%, which is outside the above range. It was found that the purification rate of hydrocarbons was higher than that of 51% to 55% of the viscosity of the slurry.
[0212]
Next, (Table 8) shows silica starting materials, hydrocarbon purification rate (%) at 250 ° C., and SO at 400 ° C.₂The relationship with the oxidation rate (%) was shown.
[0213]
[Table 8]

[0214]
As is clear from this (Table 8), when silica is formed in the production of exhaust gas purification material, when silicon alkoxide is used as a starting material, the hydrocarbon purification rate is as high as 85%, and SO₂It was found that the oxidation effect of sulfuric acid to sulfuric acid mist was 15% and the suppression effect was large. In addition, when silica sol is used as a starting material, the purification rate of hydrocarbons is 75%, SO₂When sodium silicate is used, the hydrocarbon purification rate is 50%, SO₂The oxidation rate of was 40%.
[0215]
Next, (Table 9) shows silica starting materials, alumina starting materials and hydrocarbon purification rate (%) at 250 ° C. and SO at 400 ° C.₂The relationship with the oxidation rate (%) was shown.
[0216]
[Table 9]

[0217]
As is clear from this (Table 9), when forming a composite oxide consisting of silica and alumina in the method for producing an exhaust gas purifying material, sodium silicate was used as the starting material, and aluminum nitrate was used as the alumina. If the hydrocarbon purification rate is as high as 97%, SO₂It was found that the effect of inhibiting the oxidation of sulfuric acid to sulfuric acid mist was 9%, which was a great suppression effect. On the other hand, when the silica content is sodium silicate, the alumina content is sodium hydroxide, the silica content is silica sol, the alumina content is aluminum nitrate, and the silica content is silica sol, the alumina content. When water alumina is used, the hydrocarbon purification rate is 50% to 71%, SO₂The oxidation rate was 25% to 40%.
[0218]
(Table 10) shows silica starting materials, titania starting materials and hydrocarbon purification rate (%) at 250 ° C and SO at 400 ° C.₂The relationship with the oxidation rate (%) was shown.
[0219]
[Table 10]

[0220]
As is clear from this (Table 10), when forming a composite oxide composed of silica and titania in the method for producing an exhaust gas purifying material, sodium silicate was used as the starting material, and titanium chloride was used as the titania content. The hydrocarbon purification rate is as high as 96% and SO₂It was found that the effect of inhibiting the oxidation of sulfuric acid to sulfuric acid mist was 9%, which was a great suppression effect. On the other hand, when the silica component is sodium silicate, the titania component is titanium sulfate, or the silica component is silica sol, the titania component is titanium chloride, the silica component is silica sol, and the titania component is sulfuric acid. When titanium is used, the hydrocarbon purification rate is 62% to 75%, SO₂The oxidation rate was 35% to 42%.
[0221]
Next, (Table 11) shows the ratio of Al / (Si · Al) of the composite oxide composed of silica and alumina, the hydrocarbon purification rate (%) at 250 ° C., and the SO at 400 ° C.₂The relationship with the oxidation rate (%) was shown.
[0222]
[Table 11]

[0223]
Table 12 shows the ratio of Ti / (Si · Ti) of the composite oxide composed of silica and titania, hydrocarbon purification rate (%) at 250 ° C., and SO at 400 ° C.₂The relationship with the oxidation rate (%) was shown.
[0224]
[Table 12]

[0225]
From (Table 11) and (Table 12), the ratio of Al / (Si · Al) of the composite oxide composed of silica and alumina and the ratio of Ti / (Si · Ti) of the composite oxide composed of silica and titania. Of 40 to 80, the purification rate of hydrocarbon is 90% or more, SO₂As a result, it was found that the oxidation of sulfuric acid into sulfuric acid mist was 10% or less, and the suppression effect was large. On the other hand, outside the range, the hydrocarbon purification rate is 51% to 53%, SO₂The oxidation rate of was 41% to 44%.
[0226]
Next, in (Table 13), the primary firing temperature in the case of forming the acidic oxide in Examples 1 to 5, the hydrocarbon purification rate (%) at 250 ° C., and the SO at 400 ° C.₂The relationship with the oxidation rate (%) was shown.
[0227]
[Table 13]

[0228]
As is clear from this (Table 13), from Examples 1 to 3, when the firing temperature at the time of primary firing in the case of forming an acidic oxide in the production of exhaust gas purification material is 500 ° C. to 1000 ° C., The purification rate is as high as 80% or more, SO₂It has been found that the oxidation effect of sulfuric acid to sulfuric acid mist is 20% or less, and the suppression effect is large. At a firing temperature outside the above range, the hydrocarbon purification rate is 52% to 55%, SO₂The oxidation rate was 40% to 46%.
[0229]
  From Example 4, the firing temperature at the time of primary firing when forming a composite oxide composed of silica and alumina is400 ° CAt ˜800 ° C., the hydrocarbon purification rate is as high as 91% or more, SO₂As a result, it was found that the oxidation of sulfuric acid into sulfuric acid mist was 10% or less, and the suppression effect was large. At a calcination temperature outside the above range, the hydrocarbon purification rate is 55% to 59%, SO₂The oxidation rate of was 37% to 41%.
[0230]
  From Example 5, the firing temperature at the time of primary firing in the case of forming a composite oxide composed of silica and titania is400 ° CAt ˜800 ° C., the hydrocarbon purification rate is as high as 90% or more, and SO₂As a result, it was found that the oxidation of sulfuric acid into sulfuric acid mist was 10% or less, and the suppression effect was large. At a calcination temperature outside the above range, the hydrocarbon purification rate is 56% to 61%, SO₂The oxidation rate was 42% to 45%.
[0231]
Next, (Table 14) shows the exhaust gas when the substrate coated with the carrier layer is impregnated in a solution containing a catalyst component and then formed using a freeze-drying method and when formed using a dryer. About purification material, hydrocarbon purification rate (%) at 250 ° C and SO at 400 ° C₂The oxidation rate (%) of was shown.
[0232]
[Table 14]

[0233]
As is clear from this (Table 14), comparing the case of using the freeze-drying method with the case of using a dryer, SO₂Although there was no significant difference in the oxidation rate, the purification rate of hydrocarbons was clearly higher when the freeze-drying method was used, and it was found that a highly active exhaust gas purification material could be obtained.
[0234]
Next, (Table 15), Examples 1-3, (Table 16), Examples 4, 5 and (Table 17), the coating amount when forming the acidic oxide in Comparative Examples 1-4 (wt) %), Film thickness (μm), coverage (%), hydrocarbon purification rate at 250 ° C. (%), and SO at 400 ° C.₂The oxidation rate (%) of was shown.
[0235]
[Table 15]

[0236]
[Table 16]

[0237]
[Table 17]

[0238]
As apparent from Tables 15 to 17, from Examples 1 to 3, the coating amount of the acidic oxide on the carrier is 6 wt% to 10 wt%, and the thickness of the acidic oxide layer is 0.1 μm to 20 μm, coverage on carrier is 80% to 100%, hydrocarbon purification rate is 84% or more, SO₂The oxidation rate of was 13% or less. On the other hand, when it is outside the above range, the hydrocarbon purification rate is 46% to 56%, SO₂The oxidation rate was 39% to 45%.
[0239]
Further, from Comparative Example 1, when no acidic oxide is present, the purification rate of hydrocarbons is 65%, SO₂The oxidation rate of was 51%. Thereby, it turned out that the purification rate of a hydrocarbon and the oxidation inhibitory effect to a sulfuric acid mist are favorable by presence of an acidic oxide.
[0240]
Furthermore, from Comparative Example 2, the exhaust gas purification material produced by the production method of Comparative Example 2 has a hydrocarbon purification rate of 69% to 71%, SO₂The oxidation rate of the hydrocarbon is 25% to 26%, the purification rate of the hydrocarbons of Examples 1 to 5 is 84% or more, SO₂It was found that the performance of the exhaust gas purification material was inferior compared with the oxidation rate of 13% or less.
[0241]
From Examples 4 and 5, the coating amount of the composite oxide on the support is 6 wt% to 10 wt%, the thickness of the acidic oxide layer is 0.1 μm to 20 μm, the coverage on the support is 80% to 100%, and the hydrocarbon The purification rate is over 94%, SO₂The oxidation rate of was 9% or less. On the other hand, when it is outside the above range, the hydrocarbon purification rate is 46% to 56%, SO₂The oxidation rate was 39% to 45%.
[0242]
When Example 4 and Comparative Example 3 are compared, in Example 4, the hydrocarbon purification rate is 94% or more, SO₂The oxidation rate of 9% or less is high, the hydrocarbon purification rate in Comparative Example 3 is 84% to 86%, SO₂It has been found that an exhaust gas purifying material having a higher activity can be obtained compared with an oxidation rate of 13% or less.
[0243]
【The invention's effect】
As described above, in the present invention, the following excellent effects can be realized.
[0247]
  According to the exhaust gas purifying material according to claim 1 of the present invention, the base material, the carrier layer formed on the surface of the base material, and the surface of the carrier layer were fired at 500 ° C. to 1000 ° C. and coated. An acidic oxide layer; and a catalyst component supported on the surface of the acidic oxide layer. The base material is impregnated in a slurry of the carrier coated with the acidic oxide layer, and calcined. A carrier layer coated with the acidic oxide layer is formed thereon, and the acidic oxide layer is silica starting from silicon alkoxide (precursor), and the base material is coated with the acidic oxide. The carrier is 7 wt% to 15 wt%, the viscosity of the slurry of the carrier coated with the acidic oxide is 1 cP to 300 cP, the coating amount of the acidic oxide on the carrier is 6 wt% to 10 wt%, and the acidic oxidation The thickness of the physical layer is 0.1 μm ~ 0 .mu.m, wherein from 80% to 100% coverage of the acidic oxide to the carrier, the carrier of the carrier layer has an average particle diameter of 1 m to 10 m, N²In the pore distribution measurement method by the adsorption method, the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume.After firing at 1000 ° C in the atmosphereSpecific surface area is 100m²/ G or more of heat-resistant inorganic oxide, so it is not easily poisoned by sulfur oxides even in the presence of sulfur oxides. The advantageous effect that it can be obtained. Moreover, according to the exhaust gas purifying material according to claim 2 of the present invention, the base material, the carrier layer formed on the surface of the base material, and the surface of the carrier layer are fired at 400 ° C. to 800 ° C. for coating. And the surface of the acidic oxide layer is covered with the carrier layer.GroupAnd impregnating the base material in a slurry of the carrier coated with the acidic oxide layer. Forming a carrier layer coated with the acidic oxide layer on the substrate, and the acidic oxide layer is a composite oxide formed using silica and alumina, or silica and titania, and the composite When the oxide is composed of silica and alumina, the silica is sodium silicate as the starting material, the alumina is aluminum nitrate and the Al / (Si · Al) ratio is 40 to 80, and the composite oxide is silica and In the case of titania, the starting material is silica with sodium silicate and titania with titanium chloride, and the ratio of Ti / (Si · Ti) is 40 to 80. The carrier coated with the complex oxide is 7 wt% to 15 wt%, the viscosity of the slurry of the carrier coated with the complex oxide is 1 cP to 300 cP, and the coating amount of the complex oxide on the carrier is 6 wt% 10 wt%, the thickness of the acidic oxide layer is 0.1 μm to 20 μm, the coverage of the composite oxide with respect to the carrier is 80% to 100%, and the carrier of the carrier layer has an average particle diameter of 1 μm to 10 μm, N²In the pore distribution measurement method by the adsorption method, the total pore volume is 0.3 ml / g or more and the pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume.After firing at 1000 ° C in the atmosphereSpecific surface area is 100m²It is an exhaust gas purifying material characterized by comprising a heat-resistant inorganic oxide of / g or more, and is advantageous in that it is not easily poisoned by sulfur oxide even in the presence of sulfur oxide and has excellent durability. In addition to the effect, an advantageous effect that the hydrocarbons in the exhaust gas can be efficiently purified is obtained.
[0248]
Since a carrier having a total pore volume of 0.3 ml / g or more and a pore volume having a pore diameter of 100 mm or more is 60% or more of the total pore volume, it has a bimodal structure and has a catalytic active surface area. And the purification efficiency is increased.
[0249]
With the bimodal structure of the support, it is possible to prevent the catalyst particles from sintering and to improve the durability of the catalytic activity.
[0250]
The specific surface area of the carrier is 100m²Since the amount is more than / g, the details are unknown, but the effect that the hydrocarbon can be efficiently oxidatively decomposed by the spillover phenomenon or the like is obtained.
[0251]
It is advantageous in that it is less susceptible to sulfur oxide poisoning and has excellent durability due to the repulsive action of the sulfur oxide and the composite oxide layer using at least two of silica, alumina, titania, zirconia and zinc oxide. An effect is obtained.
[0252]
acidSince the functional oxide layer is silica having silicon alkoxide as a precursor, SilicaBy using elemental alkoxide, an advantageous effect that a uniform silica coating layer can be formed on the support by a simple method called impregnation is obtained.
[0253]
acidSince the functional oxide layer is a composite oxide composed of silica with sodium silicate as a precursor and alumina with aluminum nitrate as a precursor, SilicaAn advantageous effect is obtained in that an acidic oxide is formed using sodium acid and aluminum nitrate, and a uniform coating layer made of silica and alumina can be formed on the support by a simple method called impregnation.
[0254]
acidThe ratio of Al / (Si · Al) in the composite oxide composed of silica and alumina in the conductive oxide layer is 40-80., SulfurThe yellow oxide and the composite oxide repel each other between acids, so that an advantageous effect is obtained that the sulfur oxide is less likely to approach the catalyst component and the support layer.
[0255]
acidThe oxide layer is a composite oxide composed of silica with sodium silicate as a precursor and titania with titanium chloride as a precursor.,saltAn advantageous effect is obtained in that an acidic oxide is formed using titanium fluoride and sodium silicate, and a uniform coating layer composed of silica and titania can be formed on the support by a simple method called an impregnation method.
[0256]
ShiSince the ratio of Ti / (Si · Ti) in the composite oxide consisting of Rica and Titania is 40-80, SulfurThe yellow oxide and the composite oxide repel each other between acids, so that an advantageous effect is obtained that the sulfur oxide is less likely to approach the catalyst component and the support layer.
[0259]
  The present inventionExcretionAccording to the method for producing a gas purification material, a carrier is added to an aluminum nitrate aqueous solution, mixed and stirred, a mixed solution of an aqueous sodium silicate solution and an aqueous sodium hydroxide solution is added, and a composite oxide composed of silica and alumina is formed on the surface of the carrier. After impregnating the precursor, primary firing is performed and the surface of the support is coated with a composite oxide composed of silica and alumina. Then, a slurry of the support coated with the composite oxide is produced, and then the substrate is impregnated in the slurry. Secondary firing to form a carrier layer coated with the composite oxide layer on the substrate, and then the substrate coated with the carrier layer is impregnated in a solution containing the catalyst component and then subjected to tertiary firing. When alumina is added to the acidic solution, aggregation at the isoelectric point (pH = 8 to 10) of alumina can be suppressed, and a composite oxide layer composed of silica and alumina can be uniformly formed on alumina. Advantageous effect that can be obtained.
[0261]
  The present inventionExcretionAccording to the method for producing a gas purification material, a carrier is added to a titanium chloride aqueous solution, mixed and stirred, then a sodium silicate aqueous solution is added, and the surface of the carrier is impregnated with a composite oxide precursor composed of silica and titania. After primary firing and coating the surface of the support with a composite oxide composed of silica and titania, a slurry of the support coated with the composite oxide is prepared, the substrate is impregnated in the slurry, and then subjected to secondary firing. Since a support layer coated with a composite oxide layer is formed on a substrate, and then the substrate coated with the support layer is impregnated in a solution containing a catalyst component, and then subjected to tertiary firing.,acidWhen alumina is added to the aqueous solution, it is possible to suppress aggregation at an isoelectric point (pH = 8 to 10) of alumina and to uniformly form a composite oxide layer composed of titania and silica on alumina. Effects can be obtained.
[0263]
acidSince the viscosity of the support slurry coated with the conductive oxide is 1 cP to 300 cP, EasyA uniform coating layer can be formed on the substrate by a simple method, and an advantageous effect that hydrocarbons in exhaust gas can be efficiently purified is obtained.
[0264]
  After impregnating the support in the solution of the precursor of the acidic oxide, primary firing is performed to coat the surface of the support with the acidic oxide layer.The firing temperature during primary firing is500 ° C to 1000 ° CIsso,The advantageous effect that the repulsive action between sulfur oxide which is acidic gas and acidic oxide is favorable is acquired.
[0265]
  After impregnating the support with the complex oxide precursor,Because the firing temperature during primary firing is 400 ° C to 800 ° C,acidThe repulsive action between the sulfur oxide, which is a reactive gas, and the composite oxide is good, and an advantageous effect of excellent durability is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an exhaust gas purifying material according to Embodiment 1 of the present invention.
FIG. 2 is a flowchart of an exhaust gas purification material manufacturing process according to the first embodiment.
FIG. 3 is a flowchart of an exhaust gas purification material manufacturing process according to the second embodiment.
FIG. 4 is a cross-sectional view of an exhaust gas purifying material according to Embodiment 4 of the present invention.
FIG. 5 is a flowchart of an exhaust gas purification material manufacturing process according to a fourth embodiment.
FIG. 6 is a cross-sectional view of an exhaust gas purifying material according to Embodiment 5 of the present invention.
7 is a flowchart of a manufacturing process of an exhaust gas purifying material according to Embodiment 5. FIG.
FIG. 8 is a schematic diagram of a fixed bed flow system reactor used in a catalyst activity evaluation test.
FIG. 9 SO₂Schematic diagram of the reactor used in the oxidation capacity evaluation test
[Explanation of symbols]
1 Exhaust gas purification material
2 Base material
3 Carrier layer
4 Acid oxide layer
5 Catalyst component
21 Exhaust gas purification material
22 Base material
23 Alumina layer
24 Complex oxide layer
25 Catalyst component
30 Exhaust gas purification material
31 Substrate
32 Alumina layer
33 Complex oxide layer
34 Catalyst component
40 Fixed bed flow system reactor
41, 42 Gas flow regulator
43 Liquid flow regulator
44 Vaporizer
45 Quartz tube
46 Electric furnace
47 Quartz wool
48 Exhaust gas purification material
49 NDIR CO, CO₂Gas analyzer
50 Gas chromatograph
51 reactor
52, 53, 54 Gas flow regulator
55 Gas mixer
56 quartz tube
57 electric furnace
58 quartz wool
59 Exhaust gas purification material
60 NDIR SO₂Gas analyzer

Claims (3)

A base material, a carrier layer formed on the surface of the base material, an acidic oxide layer coated on the surface of the carrier layer by baking at 500 ° C. to 1000 ° C., and supported on the surface of the acidic oxide layer A catalyst layer, and the carrier slurry coated with the acidic oxide layer is impregnated with the substrate and baked to form a carrier layer coated with the acidic oxide layer on the substrate, The acidic oxide layer is silica using silicon alkoxide as a starting material (precursor), and the support obtained by coating the acidic oxide with respect to the base material is 7 wt% to 15 wt%, and covers the acidic oxide. The carrier slurry has a viscosity of 1 cP to 300 cP, the acidic oxide coating amount on the carrier is 6 wt% to 10 wt%, the acidic oxide layer has a film thickness of 0.1 μm to 20 μm, Acid oxide coverage Is 80% to 100%, the carrier of the carrier layer has an average particle diameter of 1 μm to 10 μm, a total pore volume of 0.3 ml / g or more in the pore distribution measurement method by the N ² adsorption method, and a fine particle size. Exhaust gas purification characterized by comprising a heat-resistant inorganic oxide having a pore volume of 100 mm or more with a pore volume of 60% or more of the total pore volume, and a specific surface area after firing at 1000 ° C. in the atmosphere of 100 m ² / g or more. Wood. A base material, a carrier layer formed on the surface of the base material, an acidic oxide layer coated on the surface of the carrier layer by baking at 400 ° C. to 800 ° C., and the carrier on the surface of the acidic oxide layer wherein the coated substrate with a layer and a supported catalyst component was fired after lyophilization was impregnated with a solution containing a catalyst component, a slurry of the carrier coated with the acidic oxide layer A composite layer formed by impregnating and firing a base material to form a carrier layer coated with the acidic oxide layer on the base material, and the acidic oxide layer formed using silica and alumina or silica and titania. In the case where the composite oxide is composed of silica and alumina, the silica is sodium silicate as the starting material, the alumina is aluminum nitrate, and the ratio of Al / (Si · Al) is 40 to 80. Composite oxide And titania, the starting material is sodium silicate, titania is titanium chloride, and the Ti / (Si · Ti) ratio is 40-80, and the base material is coated with the composite oxide. The support is 7 wt% to 15 wt%, the viscosity of the support slurry coated with the composite oxide is 1 cP to 300 cP, and the coverage of the composite oxide on the support is 6 wt% to 10 wt%, The film thickness of the acidic oxide layer is 0.1 μm to 20 μm, the coverage of the composite oxide with respect to the carrier is 80% to 100%, the carrier of the carrier layer has an average particle diameter of 1 μm to 10 μm, and N ² adsorption in total pore volume in a pore distribution measurement method by law 0.3 ml / g or more and more pore volume of pores having a pore diameter of 100Å is less than 60% of the total pore volume, further atmospheric 1000 ° C. Exhaust gas purification material, wherein the specific surface area after calcination consists of 100 m 2 / ^g or more refractory inorganic oxides.   The exhaust gas purification material according to claim 1 or 2, wherein the carrier is alumina or activated alumina.

Images