CN103495425A - NOx purification catalyst efficient and capable of being regenerated easily at low temperature - Google Patents

NOx purification catalyst efficient and capable of being regenerated easily at low temperature Download PDF

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CN103495425A
CN103495425A CN201310491628.1A CN201310491628A CN103495425A CN 103495425 A CN103495425 A CN 103495425A CN 201310491628 A CN201310491628 A CN 201310491628A CN 103495425 A CN103495425 A CN 103495425A
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catalyst
layer
metal
earth metal
bauxite
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CN103495425B (en
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王秀云
陈志林
王瑞虎
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Fujian Institute of Research on the Structure of Matter of CAS
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Fujian Institute of Research on the Structure of Matter of CAS
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Abstract

The invention provides automobile exhaust NOx purification catalyst which is high in activity and capable of being generated easily at low temperature. The catalyst is high in NOx purification activity in a wide air-fuel ratio range and is wide in operational window. The prepared catalyst comprises three layers. A first layer is a bauxite substrate going through acid and heat treatment. A second layer is a composite coating composed of rare earth metal, alkaline earth metal and transition metal. A third layer is reactive metal. The catalyst maintains high NOx purifying performance. Moreover, thermal inactivated catalyst can recover most lost activity after regenerating through reducing agents 5vol%H2/Ar and CO.

Description

Catalyst for purification of nitrogen oxides efficient under low temperature, that easily regenerate
Technical field
The invention belongs to the Industrial Catalysis application, be specifically related to a kind of catalyst and be applied to the NO in purifying automobile tail gas x.
Background technology
NO xbe one of major pollutants of atmospheric environment, one of its important sources is the tail gas of vehicular emission.NO in current vehicle exhaust xcleaning catalyst mainly comprises three parts and forms, be catalyst carrier, active coating and catalytic active component, in addition, in order to improve the performance of catalyst, adding a small amount of auxiliary agent in active coating and catalyst component, is mainly rare earth oxide and alkaline earth oxide.Carrier has two kinds of geometric formats usually: spherical and honeycomb substrate, it is lower that spheroid carrier prepares simple cost, and there is higher specific area, but mechanical performance is undesirable, gas-flow resistance is large, have and much be difficult to the difficulty overcome during actual the use, the domestic research and comparison to it is many, but external research and practical application are seldom.In China, at present the research of purifying vehicle exhaust has been reached the three-way catalyst of Europe IV level, mainly adopt ceramic honeycomb material or metal as matrix, be mainly high-ratio surface, cavernous A1 in coating 2o 3and CeO 2-ZrO 2the component coating is on cordierite carrier, and active component is Pt-Pd-Rh[Hu Zhun, Sun Keqiang, the Xu Baiqing, " NO of Pt-BaO catalyst xstorage-reduction chemistry and structure-performance relation ", catalysis journal 2011,32,17-26], but the type catalyst under excess oxygen to NO xclean-up effect not good.The technology of denitration both at home and abroad mainly contains three kinds, NO at present xdirectly decompose SCR (SCR) and NO xstore/reduction (NSR) technology.Yet, no matter be current three-way catalyst or NSR or SCR catalyst, what generally adopt is all noble metal type catalyst.What these 2 kinds of purification techniques adopted is all preferably precious metals pts of catalyst performance, Pd or Rh, and its noble metal is expensive, and resource-constrained, and the heat endurance of noble metal catalyst is low, anti-SO 2poor and the easy inactivation of catalyst of poisoning performance, limited the NO in the motor-vehicle tail-gas xthe further application of cleaning catalyst.
Current NO xthe forward position research of field of purification mainly concentrates on heat endurance and the anti-SO that improves catalyst 2poisoning capability, a lot of research is absorbed in the new catalytic carrier of continuous searching or is changed original carrier to improve the catalytic performance of catalyst, and good novel catalyst carrier tool is of great significance therefore to find a kind of performance, NO xpurify common carrier Al is arranged 2o 3, CeO 2-ZrO 2deng oxide or composite oxides.In recent years, correlative study both domestic and external mainly concentrates on the purification efficiency that improves catalyst and the preparation cost that reduces catalyst, research before our seminar's combination, take bauxite as matrix, and the composite coating by rare earth metal, alkaline-earth metal and transition metal and active metal composition has prepared three layers of vehicle exhaust NO xcleaning catalyst.And by the simulation of in esse various severe atmosphere in automobile, the NO of detecting catalyst xpurifying property.
Summary of the invention
The NO that the purpose of this invention is to provide a kind of low temperature, high activity, easy regeneration xthe SCR cleaning catalyst, this catalyst all shows high NO in wider air-fuel ratio scope xpurify active, but and action pane wider.
Cleaning catalyst for tail gases of automobiles provided by the invention comprises 3 layers, and ground floor is to adopt acid and heat treated bauxite matrix, and the second layer is the composite coating that rare earth metal, alkaline-earth metal and transition metal form, and the 3rd layer is Ni, Ag, Mn, V 2o 5, a kind of or any two kinds of combinations in W and Mo etc.
Matrix in described catalyst is acid and heat treated bauxite, it is characterized in that: described acid and heat treatment alum clay ore deposit adopt following way to prepare: through weak acid, hydro-thermal, reaming, roasting and hydrogen treat. specific as follows: the pretreatment of (1) bauxite matrix: a: weak acid pretreatment 2-10h, process 48-96h for hydro-thermal 130-170 ℃, sintering temperature 400-550 ℃, hydrogen reducing 4-8h.(2) second layer and the 3rd layer are coated on the bauxite base by coating way under 60-80 ℃ and rapid stirring, and dry; (3) then 400-550 ℃ of roasting.It is 170-200m that bauxite after processing utilizes nitrogen adsorption/desorption test specific area under liquid nitrogen temperature is-196 ℃ 2/ g, preferably 190-200m 2/ g.
The described catalyst second layer is the composite coating that rare earth metal, alkaline-earth metal and transition metal form, and it is characterized in that: under agitation rare earth metal, alkaline-earth metal and transition metal are joined in the slurry of matrix of bauxite to mixing time 1～6h.
The 3rd layer of described catalyst is by Ni, Ag, Mn, V 2o 5, a kind of or any two kinds of compositions in W and Mo etc., it is characterized in that: by approaching real vehicle exhaust composition simulation test, preferably Ag and Mn, then by the Ag of different content and the NO of Mn xthe purifying property assessment, the 3-6% left and right that the content that optimizes Ag and Mn is the carrier Theoretical Mass, continue to increase content and can cause NO xpurifying property reduces.
The renovation process of described decaying catalyst is characterized in that: be included under reducing condition the catalyst of inactivation is contacted by reducing gas, catalyst is adopted to reducing agent 5vol%H 2/ Ar and CO regeneration.Recovery time is 30min-12h, preferably 60-90min.
Catalyst of the present invention all shows NO preferably in wider air-fuel ratio (A/F) in 0-16 xpurifying property, but and operating temperature window wider (100-500 ℃).
The accompanying drawing explanation
The NO that Fig. 1 is different catalysts xcatalytic performance;
Fig. 2 is that different air-fuel ratios are to catalyst outlet NO ximpact.
The specific embodiment
The present invention is for NO xthe catalyst of purifying and catalyzing, can be used with particle form, also can be used as coating load and make integral catalyzer on monolithic porous matrix.
NO of the present invention xcleaning catalyst can be carried on separately on a matrix as catalyst, also can mix with current three-way catalyst component and form a multicomponent catalyst.
Below in conjunction with embodiment, more specifically catalyst of the present invention is illustrated, but these embodiment are without any restrictions to scope of the present invention.
Embodiment 1
(1) first step of the present invention is to process the bauxite matrix, the composite coating that the second layer of catalyst is comprised of rare earth metal, alkaline-earth metal and transition metal, be specially: under agitation rare earth metal (La or Nd) alkaline-earth metal (K or Ba) alkaline-earth metal (Fe, Co) is joined in the slurry of matrix of bauxite, stir 1～6h.Spend the night through 120 ℃ of oven dry, after oven dry, the sample grind into powder is added to a certain amount of water, by quick agitator, that slurry agitation is even.The 3rd layer is the coating of reactive metal, is specially: will be furnished with the salting liquid of the silver nitrate that contains 1-10wt%, it is coated with in the slurries that prepare in front.Through 120 ℃ of oven dry, spend the night, 550 ℃ of roasting 4h, obtain cleaning catalyst for tail gases of automobiles.Be labeled as catalyst 1.
(2) contrast sample Pt/Al 2o 3and Ag/Al 2o 3preparation process: (i) Al 2o 3synthetic: Al (NO 3) 39H 2o is raw material, is dissolved in a certain amount of distilled water, with NH 3h 2o is precipitating reagent, centrifugal, oven dry, 400-550 ℃ roasting.(ii) H on coating 2ptCl 66H 2o and AgNO 3.Its mass fraction is all 1wt%, and it is standby that the 20-30 order is got in oven dry.Be labeled as the contrast sample.
Embodiment 2
The ground floor of catalyst and the second layer are with embodiment 1.The 3rd layer for the coating of reactive metal is Ni, is specially: will be furnished with the nickel nitrate solution that contains 1-10wt%, it is coated with in the slurries that prepare in front.Through 120 ℃ of oven dry, spend the night, 550 ℃ of roasting 4h, obtain cleaning catalyst for tail gases of automobiles.Be labeled as catalyst 2
(2) contrast sample Pt/Al 2o 3and Ag/Al 2o 3preparation process: (i) Al 2o 3synthetic: Al (NO 3) 39H 2o is raw material, is dissolved in a certain amount of distilled water, with NH 3h 2o is precipitating reagent, centrifugal, oven dry, 400-550 ℃ roasting.(ii) H on coating 2ptCl 66H 2o and AgNO 3.Its mass fraction is all 1wt%, and it is standby that the 20-30 order is got in oven dry.
Embodiment 3
(1) ground floor of catalyst and the second layer are with embodiment 1.The 3rd layer for the coating of reactive metal is Mn, is specially: will be furnished with the manganese nitrate solution that contains 1-10wt%, it is coated with in the slurries that prepare in front.Through 120 ℃ of oven dry, spend the night, 550 ℃ of roasting 4h, obtain cleaning catalyst for tail gases of automobiles.Be labeled as catalyst 3.
(2) contrast sample Pt/Al 2o 3and Ag/Al 2o 3preparation process: (i) Al 2o 3synthetic: Al (NO 3) 39H 2o is raw material, is dissolved in a certain amount of distilled water, with NH 3h 2o is precipitating reagent, centrifugal, oven dry, 400-550 ℃ roasting.(ii) H on coating 2ptCl 66H 2o and AgNO 3.Its mass fraction is all 1wt%, and it is standby that the 20-30 order is got in oven dry.
Below the performance of embodiment catalyst is estimated
Test under 1 different temperatures catalyst to NO xconversion ratio
Adopt respectively embodiment 1-3 and contrast sample Pt/Al 2o 3each 0.5g of catalyst, gas flow rate 600mL/min, air speed 72,000h -1, on the miniature fixed bed of continuous-flow, carry out NO xpurifying property is measured, NO in tail gas xchange in concentration is by chemiluminescence NO-NO 2-NO xanalyzer detects (Thermo, 42i-HL).Reacting gas consists of: 240ppm NO, 8vol%O 2, 8vol%CO 2, N 2for Balance Air.Respectively at 100 ℃, 200 ℃, 250 ℃, 300 ℃, 350 ℃, measure catalyst to NO under 400 ℃ xchanging effect, test result is shown in Fig. 1.
As can be seen from Figure 1, described catalyst 1,2 and 3 is than contrast sample Pt/Al 2o 3there is NO preferably xconversion ratio, T=350 ℃, catalyst 1,2 and 3 NO xbe converted into N 2conversion ratio be respectively 94.63%, 93.56% and 86.81%.Under equal conditions contrast sample Pt/Al 2o 3nO xconversion ratio is 60.81%.
Test the regeneration of 2 decaying catalysts
Catalyst is inactivation 4% after the test through 3 weeks, adopts the edetate solution washing, dry, roasting.Again catalyst is adopted to reducing agent 5vol%H 2/ Ar and CO mist, at 550 ℃ of regeneration 30min, 60min, 90min, 12h does not wait, the research discovery, catalyst is after the regeneration of 60-90min, and the catalyst activity of inactivation recovers the 3-3.5% left and right, continues to extend the recovery time, and the activity keeping of recovery is constant.
Test the test of 3 different air-fuel ratios
That selects catalyst activity the best carries out different air-fuel ratio tests (A/F), and probe temperature is 350 ℃, and the gas component of test is 240ppm NO, 8vol%CO 2, N 2for Balance Air and a certain amount of O 2and H 2according to different air-fuel ratios, switched.The air-fuel ratio excursion is 0-10.Experimental result is shown in Fig. 2.
The foregoing is only preferred embodiment of the present invention, every modification according to doing in the present patent application the scope of the claims and all changes, all should belong to covering scope of the present invention.

Claims (8)

1. one kind for the purifying nitrogen oxide cleaning catalyst, this catalyst comprises three layers, it is matrix that ground floor adopts the bauxite after acid and heat treatment, the second layer is composite coating, the 3rd layer is reactive metal, it is characterized in that: described composite coating is comprised of rare earth metal, alkaline-earth metal and transition metal.
2. according to the catalyst of claim 1, it is characterized in that: described acid and heat treatment alum clay ore deposit adopt following way to prepare: through weak acid, hydro-thermal, reaming, roasting and hydrogen treat.
3. according to the catalyst of claim 1, it is characterized in that: described rare earth is selected from La or Nd, and described alkaline-earth metal is selected from K or Ba, and described transition metal is selected from Fe, Co.
4. catalyst according to claim 1, is characterized in that: described reactive metal employing Ni, Ag, Mn, V 2o 5, a kind of or any two kinds of combinations in W and Mo.
5. according to the arbitrary described catalyst of claim 1 to 4, it is characterized in that: described reactive metal accounts for the 3-10% of catalyst gross mass mark.
6. a method for preparing the arbitrary described catalyst of claim 1 to 4 comprises step by step rapid as follows:
(1) pretreatment of bauxite matrix: (a) weak acid pretreatment 2-10h, hydro-thermal 130-170 ℃, process 48-96h, sintering temperature 400-550 ℃, hydrogen reducing 4-8h.
(2) second layer and the 3rd layer are coated in the bauxite matrix by coating way under 60-80 ℃ and rapid stirring condition, and dry;
(3) then 400-550 ℃ of roasting.
7. the arbitrary described catalyst of claim 1 to 4 is applied to purify the nitrogen oxide in moving source.
8. the renovation process of the arbitrary described catalyst of claim 1 to 4: comprise the steps:
(1) temperature programmed desorption;
(2) desorption gas is 5Vol%H2/Ar and CO, and the recovery time is 30min-12h.
CN201310491628.1A 2013-10-21 2013-10-21 NOx purification catalyst efficient and capable of being regenerated easily at low temperature Active CN103495425B (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104437512A (en) * 2014-11-02 2015-03-25 中国科学院福建物质结构研究所 Transition-metal-modified Cu/CeO2 ordered mesopore material for NOx purification of stationary source
CN105251543A (en) * 2015-10-20 2016-01-20 清华大学 Method for regenerating arsenic-poisoned denitration catalysts through hydrogen gas reduction
CN105879924A (en) * 2016-04-27 2016-08-24 北京石油化工学院 Method for reduction pretreatment of supported noble metal catalyst
CN107930637A (en) * 2017-12-05 2018-04-20 内蒙古科技大学 A kind of high entropy solid solution catalyst of rare-earth-based iron content and preparation method thereof
CN111182965A (en) * 2017-07-27 2020-05-19 巴斯夫公司 Removal of N from vehicle exhaust of lean/rich systems2O
CN116688987A (en) * 2023-07-28 2023-09-05 四川大学 Biological catalyst for producing ROS, preparation method and application thereof

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Publication number Priority date Publication date Assignee Title
US20030171216A1 (en) * 2001-12-18 2003-09-11 Park Paul W. Method of preparing metal or metal oxide doped oxide catalysts having high deNOx selectivity for lean NOx exhaust aftertreatment systems
CN102580730A (en) * 2011-01-12 2012-07-18 北京化工大学 Catalyst for purifying automobile tail gas and preparation method thereof
CN102580764A (en) * 2012-02-06 2012-07-18 中国科学院福建物质结构研究所 Catalyst for purifying nitric oxide, and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030171216A1 (en) * 2001-12-18 2003-09-11 Park Paul W. Method of preparing metal or metal oxide doped oxide catalysts having high deNOx selectivity for lean NOx exhaust aftertreatment systems
CN102580730A (en) * 2011-01-12 2012-07-18 北京化工大学 Catalyst for purifying automobile tail gas and preparation method thereof
CN102580764A (en) * 2012-02-06 2012-07-18 中国科学院福建物质结构研究所 Catalyst for purifying nitric oxide, and preparation method thereof

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104437512A (en) * 2014-11-02 2015-03-25 中国科学院福建物质结构研究所 Transition-metal-modified Cu/CeO2 ordered mesopore material for NOx purification of stationary source
CN105251543A (en) * 2015-10-20 2016-01-20 清华大学 Method for regenerating arsenic-poisoned denitration catalysts through hydrogen gas reduction
CN105251543B (en) * 2015-10-20 2018-08-28 清华大学 A kind of hydrogen reducing regeneration method of the out of stock catalyst of arsenic poisoning
CN105879924A (en) * 2016-04-27 2016-08-24 北京石油化工学院 Method for reduction pretreatment of supported noble metal catalyst
CN111182965A (en) * 2017-07-27 2020-05-19 巴斯夫公司 Removal of N from vehicle exhaust of lean/rich systems2O
CN111182965B (en) * 2017-07-27 2023-10-27 巴斯夫公司 Removal of N from automobile exhaust of lean/rich system 2 O
CN107930637A (en) * 2017-12-05 2018-04-20 内蒙古科技大学 A kind of high entropy solid solution catalyst of rare-earth-based iron content and preparation method thereof
CN116688987A (en) * 2023-07-28 2023-09-05 四川大学 Biological catalyst for producing ROS, preparation method and application thereof
CN116688987B (en) * 2023-07-28 2023-10-10 四川大学 Biological catalyst for producing ROS, preparation method and application thereof

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