CN1657139A - Preparation of nitnogen oxide storing-reducing catalyst and method for eliminating nitrogen oxide by storing and reduction - Google Patents

Preparation of nitnogen oxide storing-reducing catalyst and method for eliminating nitrogen oxide by storing and reduction Download PDF

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Publication number
CN1657139A
CN1657139A CN 200410021148 CN200410021148A CN1657139A CN 1657139 A CN1657139 A CN 1657139A CN 200410021148 CN200410021148 CN 200410021148 CN 200410021148 A CN200410021148 A CN 200410021148A CN 1657139 A CN1657139 A CN 1657139A
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catalyst
reducing
reduction
storage
nitrogen oxides
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CN 200410021148
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陈光文
程昊
吴迪镛
王树东
张引
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Dalian Institute of Chemical Physics of CAS
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Dalian Institute of Chemical Physics of CAS
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Abstract

A catalyst for eliminating NOx by storing it and then reducing it by H2 is prepared through compound oxide of Mg and Al, using MgO as catalyst carrier, and immersing said carrier in the Pt(NH3)4(OH)2 solution to obtain Pt/Mg/Al-O and Pt/MgO catalysts. Its advantages are high low-temp activity and high conversion rate of NOx.

Description

A kind of nitrogen oxides storage-reducing catalyst preparation and storage-reduction are eliminated the method for nitrogen oxide
Technical field:
The invention belongs to field of environment protection, specially refer to the method for storage-reduction elimination nitrogen oxide in oxygen-enriched atmosphere.
Background technology:
Lean-combustion engine is strong with its power performance, fuel availability height, advantage such as good environmental protection and obtained promoting the use of widely.But this class engine produces the oxygen enrichment exhaust, and the oxygen of high-load makes traditional three-way catalyst to NO in its tail gas xReducing activity very low.How under oxygen-enriched atmosphere, effectively to eliminate NO xBecome the focus of environmental catalysis area research, various countries' industrial circle and academia have all carried out a large amount of work.Solution that studied already or just under development comprises that direct decomposition, SCR (SCR) and storage reduction (NSR) are several.The direct decomposition of NO is very low because of the existence activity of excess of oxygen, and is considered to be not suitable for actual use.The reducing agent that SCR uses mainly contains NH 3, urea, hydrocarbon, hydrogen and organic oxygen-containing compound, catalyst system and catalyzing comprises that noble metal, zeolite and metal oxide are several.But all there are some problems in the catalytic reduction system that existing catalyst and reducing agent are formed, as: zeolite catalyst hydrothermal stability and anti-sulphur are poor, the narrow and employing corrosive gas NH of noble metal catalyst temperature window 3Storage that brings and transportation problem etc., these have all limited the use of this method.The NSR method is the technology that another kind obtains broad research, it proposes (Eur.Patent 0573672A1) by Toyota Motor Corporation at first, its cardinal principle is by the improvement of engine or DESIGN OF REACTOR, make tail gas atmosphere can be between oxidizing atmosphere and reducing atmosphere the cycle change.At oxidation panel, NO xForm with nitrate is stored in the sorbing material of catalyst; At reduction section, the NO of storage xBe reduced the agent catalytic reduction.Typical NSR catalyst consists of the primer Al of high-ratio surface 2O 3, the noble metal of catalytic oxidation/reduction reaction and storage NO xThe oxide of material barium.This catalyst is to SO 2Very responsive, SO 2Be oxidized to SO 3And further generate BaSO with BaO 4, the latter is difficult to decompose or be reduced in lean-combustion engine exhaust temperature scope, causes catalyst to lose storage NO gradually xAbility and inactivation.Therefore, the sulfur poisoning problem of solution catalyst has become the key of this method practicability.
The technology contents of invention:
The present invention aims to provide a kind of nitrogen oxides storage-reducing catalyst, and Preparation of Catalyst reaches the method for eliminating nitrogen oxide based on this catalyst stores-reduction, its low temperature elimination NO xActive good, the sulfur poisoning-resistant ability is strong.
The invention provides a kind of nitrogen oxides storage-reducing catalyst, is active component with the noble metal, it is characterized in that: with the Mg base oxide is carrier.
In nitrogen oxides storage-reducing catalyst of the present invention, described Mg base oxide is MgO.
In nitrogen oxides storage-reducing catalyst of the present invention, described Mg base oxide is the Mg-Al-O composite oxides, and the MgO weight ratio is between 21～70%, and the Mg/Al atomic ratio is between 0.33～3.
In nitrogen oxides storage-reducing catalyst of the present invention, described activity of such catalysts component is Pt, and Pt content is 0.3～2%.Pt content is preferably 0.8～1.2%.
The present invention provides the preparation method of above-mentioned nitrogen oxides storage-reducing catalyst simultaneously, it is characterized in that preparing the Mg base oxide as carrier with coprecipitation, the noble metal aqueous solution of solubility is mixed with required concentration to be immersed on the carrier, through 50～90 ℃ of dryings 2～5 hours, 300～500 ℃ of roastings made catalyst in 2～4 hours.
The present invention also provides a kind of in addition and has eliminated NO based on above-mentioned catalyst stores-reduction xMethod, be characterised in that: reaction atmosphere cyclical swing between oxidisability and reducing atmosphere, under oxidizing atmosphere, store NO x, behind the certain hour, transfer reducing atmosphere to, the NO of storage xBe reduced the agent reduction, so the cycle repeats, and can eliminate NO effectively between 150～400 ℃ x
Storage-reduction of the present invention is eliminated NO xMethod in, preferably adopt H during low temperature 2Be reducing agent, preferably adopt C during high temperature 3H 6Or H 2Be reducing agent.
The present invention adopts oxide than the Mg a little less than the Ba alkalescence as storage medium, and adopting precious metals pt is the active component of catalytic oxidation/reduction reaction, adopts H 2Or C 3H 6Be reducing agent, have low temperature elimination NO xActive good, the advantage that the sulfur poisoning-resistant ability is strong.
The specific embodiment:
May further comprise the steps:
(1) #The preparation of Mg-Al-O composite oxides.Preparation in proportion #Mg (NO 3) 26H 2O and Al (NO 3) 39H 2O solution, wherein Mg 2+And Al 3+Mol ratio be 0.33～3, Mg 2+And Al 3+Total concentration is 1.25mol L -1Preparation NaOH and Na 2CO 3Solution, wherein the mol ratio of NaOH and sodium carbonate is 16: 1.Above-mentioned two solution are added drop-wise in the there-necked flask that fills the 200ml deionized water with the speed of 170～200mL/h respectively, the while strong agitation, the control co-precipitation temperature is 60 ℃.After dropwising, gained is deposited in aging 10h in 70 ℃ the water bath with thermostatic control, filtration washing 6 times, 100 ℃ of dry 10h also behind the roasting 5h, obtain the Mg-Al-O composite oxide carrier in 600 ℃ of air atmospheres.
(2) preparation of MgO carrier.Preparation Mg (NO 3) 26H 2O solution, wherein Mg 2+Concentration is 1.25mol L -1Preparation NaOH and Na 2CO 3Solution, wherein the mol ratio of NaOH and sodium carbonate is 16: 1.Above-mentioned two solution are added drop-wise in the there-necked flask that fills the 200ml deionized water with the speed of 170～200mL/h respectively, the while strong agitation, the control co-precipitation temperature is 60 ℃.After dropwising, gained is deposited in aging 10h in 70 ℃ the water bath with thermostatic control, filtration washing 6 times, 100 ℃ of dry 10h also behind the roasting 5h, obtain the MgO carrier in 600 ℃ of air atmospheres.
(3) with equi-volume impregnating load active component Pt.With Pt (NH 3) 4(OH) 2Solution impregnation is on Mg-Al-O and MgO carrier, and the weight percentage that control Pt accounts for carrier is 1%, and at one night of natural air drying in air, continuously at 50 ℃, 70 ℃ and 90 ℃ are each drying 1 hour down, and roasting is 3 hours in 500 ℃ of air atmospheres, contains 8%H at 400 ℃ 2Nitrogen stream in reduction 1 hour, contain 8%O at 400 ℃ 2Nitrogen stream in oxidation obtained catalyst in 1 hour.
(4) catalyst that above-mentioned the 3rd step is obtained is seated in the reactor, and reaction velocity is controlled at 0.75g min/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first under oxidizing atmosphere, store NO x, behind the certain hour, transfer reducing atmosphere to, the NO that stores in the oxidation panel xBe reduced the agent reduction, so the cycle repeats.Adopt H during low temperature 2Be reducing agent, adopt C during high temperature 3H 6Or H 2Be reducing agent.
Embodiment 1
With 76.8g Mg (NO 3) 26H 2O and 37.5g Al (NO 3) 39H 2O is dissolved in the 320mL deionized water and makes solution A, with 32.76g NaOH and 5.43g Na 2CO 3Be dissolved in the 320mL deionized water and make solution B, above-mentioned two solution are added drop-wise in the there-necked flask that fills the 200mL deionized water with the speed of 170～200mL/h respectively, the while strong agitation, the control co-precipitation temperature is 60 ℃.After dropwising, gained is deposited in aging 10h in 70 ℃ the water bath with thermostatic control, with deionized water filtration washing 6 times, 100 ℃ of dry 10h, in 600 ℃ of air atmospheres behind the roasting 5h, crushing and screening is got granularity 30～50 orders and is obtained the Mg-Al-O composite oxide carrier.With 0.7496g Pt content 6.67% Pt (NH 3) 4(OH) 2Solution is diluted to 7.5g with deionized water and is immersed on the 5g Mg-Al-O carrier, 1 night of natural air drying in air, and continuously at 50 ℃, 70 ℃ and 90 ℃ each dry 1 hour down, roasting is 3 hours in 500 ℃ of air atmospheres, and 400 ℃ are containing 8%H 2Nitrogen stream in reduction 1 hour, contain 8%O in 400 ℃ again 2Nitrogen stream in oxidation 1 hour, obtain the Pt/Mg-Al-O catalyst.Catalyst is seated in the reactor, and reaction velocity is controlled at 0.75g min/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first in oxidizing atmosphere, store NO x3 minutes, oxidizing atmosphere consisted of 550ppm NO+7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+800ppmC 3H 6+ N 2The reducing gases of balance 2 minutes, so the cycle repeats.Obtain NO in the time of 400 ℃ xConversion ratio is 81%.
Embodiment 2
Adopt the preparation method identical to prepare the MgO carrier, but be dissolved with 76.8g Mg (NO with 240mL with embodiment 1 3) 26H 2The aqueous solution of O replaces solution A, is dissolved with 21.84gNaOH and 3.62g Na with 240mL 2CO 3The aqueous solution replace solution B.With 0.2985g Pt content 6.67% Pt (NH 3) 4(OH) 2Solution is diluted to 4.7g with deionized water and is immersed on the 2g MgO carrier, 1 night of natural air drying in air, and continuously at 50 ℃, 70 ℃ and 90 ℃ each dry 1 hour down, roasting is 3 hours in 500 ℃ of air atmospheres, and 400 ℃ are containing 8%H 2Nitrogen stream in reduction 1 hour, contain 8%O in 400 ℃ again 2Nitrogen stream in oxidation obtained the Pt/MgO catalyst in 1 hour.Catalyst is seated in the reactor, and reaction velocity is controlled at 0.75g min/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first at oxidizing atmosphere storage NO x3 minutes, oxidizing atmosphere consisted of 550ppm NO+7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+800ppm C 3H 6+ N 2The reducing gases of balance 2 minutes, so the cycle repeats.NO in the time of 350 ℃, 400 ℃, 450 ℃ xConversion ratio is respectively 89%, 94% and 76%.
Embodiment 3
The catalyst that embodiment 2 is made is seated in the reactor, and reaction velocity is controlled at 0.75g min/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first in oxidizing atmosphere, store NO x2 minutes, oxidizing atmosphere consisted of 550ppm NO+7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+800ppm C 3H 6+ N 2The reducing gases of balance 1 minute.The cycle like this repeats 10 hours, NO in the time of 400 ℃ xConversion ratio is stabilized in 95% always.
Embodiment 4
The catalyst that embodiment 1 is made is seated in the reactor, and reaction velocity is controlled at 0.75g min/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first at oxidizing atmosphere storage NO x100 seconds, oxidizing atmosphere consisted of 550ppm NO+7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+6000ppm H 2+ N 2The reducing gases reduction of balance 40 seconds, so the cycle repeats, between 150～400 ℃, NO xConversion ratio is 88～99%.
Embodiment 5
The catalyst that embodiment 2 is made is seated in the reactor, and reaction velocity is controlled at 0.75gmin/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first at oxidizing atmosphere storage NO x100 seconds, oxidizing atmosphere consisted of 550ppm NO+7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+6000ppm H 2+ N 2The reducing gases of balance 40 seconds, so the cycle repeats, between 150～400 ℃, NO xConversion ratio is 71～98%.
Embodiment 6
The catalyst that embodiment 2 is made is seated in the reactor, and reaction velocity is controlled at 0.75gmin/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first at oxidizing atmosphere storage NO x2 minutes, oxidizing atmosphere consisted of 550ppm NO+30ppm SO 2+ 7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+30ppm SO 2+ 800ppm C 3H 6+ N 2The reducing gases of balance 1 minute, the cycle like this repeats 5 hours NO in the time of 400 ℃ xConversion ratio drops to 72% by 95%.
Comparative example
Get the Al that 10g Shandong Aluminum Plant produces 2O 3(200 now), with equi-volume impregnating with 0.306mol/LBa (NO 3) 2Solution impregnation thereon.After air-dry 3 hours, drying is 3 minutes in micro-wave oven in the air, changes over to then in the Muffle furnace in 550 ℃ of calcinings 2 hours.Repeat above-mentioned steps again and make BaO/Al 4 times 2O 3Carrier.'s 6.67% Pt (NH with equi-volume impregnating with 0.7484g Pt content 3) 4(OH) 2Solution is diluted to 4.7g with deionized water, is immersed in 5g BaO/Al 2O 3On the carrier, dried naturally for 1 night in the air, continuously at 50 ℃, 70 ℃ and 90 ℃ were descended each dry 1 hour, and roasting is 3 hours in 500 ℃ of air atmospheres, and 400 ℃ are containing 8%H 2Nitrogen stream in reduction 1 hour, contain 8%O in 400 ℃ again 2Nitrogen stream in oxidation obtained Pt/BaO/Al in 1 hour 2O 3Catalyst.Catalyst is got 30～50 orders and is packed in the reactor behind compressing tablet, crushing and screening, reaction velocity is controlled at 0.75g min/L, reaction atmosphere cyclical swing between oxidisability and reducing atmosphere.At first at oxidizing atmosphere storage NO x2 minutes, oxidizing atmosphere consisted of 550ppm NO+30ppm SO 2+ 7.8%O 2+ N 2Balance; Feed then and consist of 550ppm NO+30ppm SO 2+ 800ppm C 3H 6+ N 2The reducing gases of balance 1 minute, the cycle like this repeats 5 hours, NO in the time of 400 ℃ xConversion ratio drops to 18% by 79%.

Claims (8)

1, a kind of nitrogen oxides storage-reducing catalyst is an active component with the noble metal, it is characterized in that: with the Mg base oxide is carrier.
2, according to the described nitrogen oxides storage-reducing catalyst of claim 1, it is characterized in that: described Mg base oxide is MgO.
3, according to the described nitrogen oxides storage-reducing catalyst of claim 1, it is characterized in that: described Mg base oxide is the Mg-Al-O composite oxides, and the MgO weight ratio is between 21～70%, and the Mg/Al atomic ratio is between 0.33～3.
4, according to claim 1,2 or 3 described nitrogen oxides storage-reducing catalysts, it is characterized in that: described activity of such catalysts component is Pt, and Pt content is 0.3～2%.
5, according to the described nitrogen oxides storage-reducing catalyst of claim 4, it is characterized in that: Pt content is 0.8～1.2%.
6, the preparation method of the described nitrogen oxides storage-reducing catalyst of a kind of claim 1, it is characterized in that preparing the Mg base oxide as carrier with coprecipitation, the noble metal aqueous solution of solubility is mixed with required concentration to be immersed on the carrier, through 50～90 ℃ of dryings 2～5 hours, 300～500 ℃ of roastings made catalyst in 2～4 hours.
7, a kind of based on the described catalyst stores of claim 1-reduction elimination NO xMethod, be characterised in that: reaction atmosphere cyclical swing between oxidisability and reducing atmosphere, under oxidizing atmosphere, store NO x, behind the certain hour, transfer reducing atmosphere to, the NO of storage xBe reduced the agent reduction, so the cycle repeats, and can eliminate NO effectively between 150～400 ℃ x
8, eliminate NO according to the described catalyst stores of claim 7-reduction xMethod, it is characterized in that: adopt H during low temperature 2Be reducing agent, adopt C during high temperature 3H 6Or H 2Be reducing agent.
CN 200410021148 2004-02-16 2004-02-16 Preparation of nitnogen oxide storing-reducing catalyst and method for eliminating nitrogen oxide by storing and reduction Pending CN1657139A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007049778A1 (en) * 2005-10-24 2007-05-03 Toyota Jidosha Kabushiki Kaisha Catalyst support and catalyst for exhaust-gas purification
CN101291731B (en) * 2005-10-24 2012-07-04 丰田自动车株式会社 Catalyst support and catalyst for exhaust-gas purification
CN104959035A (en) * 2006-05-29 2015-10-07 株式会社卡特勒 NOx reduction catalyst system and NOx reduction method
CN105074151A (en) * 2013-04-04 2015-11-18 五十铃自动车株式会社 Method for determining degradation of NOx storage reduction catalyst in exhaust gas aftertreatment device
CN111032195A (en) * 2017-08-15 2020-04-17 康明斯排放处理公司 Ammonia production from engine exhaust at ambient conditions using water gas shift catalyst and ammonia synthesis catalyst

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007049778A1 (en) * 2005-10-24 2007-05-03 Toyota Jidosha Kabushiki Kaisha Catalyst support and catalyst for exhaust-gas purification
US7776783B2 (en) 2005-10-24 2010-08-17 Toyota Jidosha Kabushiki Kaisha Catalyst carrier and exhaust gas purification catalyst
CN101291731B (en) * 2005-10-24 2012-07-04 丰田自动车株式会社 Catalyst support and catalyst for exhaust-gas purification
CN104959035A (en) * 2006-05-29 2015-10-07 株式会社卡特勒 NOx reduction catalyst system and NOx reduction method
CN105074151A (en) * 2013-04-04 2015-11-18 五十铃自动车株式会社 Method for determining degradation of NOx storage reduction catalyst in exhaust gas aftertreatment device
CN111032195A (en) * 2017-08-15 2020-04-17 康明斯排放处理公司 Ammonia production from engine exhaust at ambient conditions using water gas shift catalyst and ammonia synthesis catalyst
CN111032195B (en) * 2017-08-15 2022-03-04 康明斯排放处理公司 Method for treating exhaust gas in an aftertreatment system and exhaust aftertreatment system

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