CN103182305B - A kind of three-way catalyst and preparation method thereof - Google Patents
A kind of three-way catalyst and preparation method thereof Download PDFInfo
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- CN103182305B CN103182305B CN201110443256.6A CN201110443256A CN103182305B CN 103182305 B CN103182305 B CN 103182305B CN 201110443256 A CN201110443256 A CN 201110443256A CN 103182305 B CN103182305 B CN 103182305B
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Abstract
The invention provides a kind of three-way catalyst, taking porous ceramics as matrix, which is provided with Catalytic Layer, described Catalytic Layer comprises the first Catalytic Layer and the second Catalytic Layer; Described the first Catalytic Layer comprises the first catalysed partial and the second catalysed partial, and described the second Catalytic Layer comprises the 3rd catalysed partial and the 4th catalysed partial; Wherein, the 3rd catalysed partial be positioned at the first catalysed partial under, the 4th catalysed partial be positioned at the second catalysed partial under. The present invention also provides the preparation method of this catalyst. The catalytic performance of HC, the CO of the catalyst that the present invention makes before aging, NOx is good, and after certain condition aging, catalytic performance is still good, has embodied good ageing resistance.
Description
Technical field
The present invention relates to automobile exhaust pollution thing (CO, HC, NOX) play the rare earth combined oxidation of three-way emission control effectThing-noble metal honeycomb catalyst and preparation method thereof.
Background technology
The object of catalytic cleaning of car tail gas is exactly that harmful CO and HC are oxidized to CO2And H2O, by NOXBe reduced into N2。Because the chemical composition of vehicle exhaust is very complicated, its conversion ratio except and outside the Pass the activity of catalyst has, also and reaction gas be to be oxidizedProperty gas or reducibility gas are relevant, and therefore catalyst is divided into oxidized form and reduced form two parts in function.
The oxidation reaction of the main catalysis CO of oxidation catalyst and HC, key reaction is as follows:
2CO+O2——2CO2
4HC+5O2——4CO2+2H2O
HC+NO2——CO2+H2O
The main catalyzing N O of reduction catalystXReduction reaction:
2NO+CO——N2+CO2
2NO+HC——N2+H2O+CO2
Because of the chemical environment difference of two kinds of reaction requirements, therefore early stage catalyst is discrete by both. Afterwards due to engineImprovement, realized the chemical environment that can make two kinds of function compatibilities; Due to the improvement of catalyst preparation technology, make oxidation and reductionTwo kinds of activated centres coexist on same catalyst, have finally occurred three-way catalyst TWC(Three – waycatalyst).
Current three-way catalyst preparation is mainly on cordierite honeycomb ceramic carrier, to apply one deck to have high-ratio surfaceLong-pending aluminum oxide coating layer is with better carried noble metal, if patent of invention CN101161337A is using cordierite honeycomb ceramics as baseBody, taking porous ceramics as matrix, which is provided with Catalytic Layer, wherein, ground floor Catalytic Layer be activated alumina support rare earth metal,The mixing of one or more in alkaline-earth metal, second layer Catalytic Layer is that aluminium oxide supports and has mithridatism and non-zero residual activityThe first active noble metals, also comprise that the 3rd layer of Catalytic Layer is second noble metal with catalytic activity, the 4th layer of Catalytic Layer isThe oxide of rare earth, alkaline earth or transition metal.
This catalyst has good catalytic performance and heat endurance, and adapts to wider air-fuel ratio scope,Efficiency with oxidation in wider scope and reduction is all higher, but the oxide of alkaline-earth metal and rare earth metal and your goldBelong to respectively in different layers, total number of plies is 4 layers, and general thickness is larger, gas diffusion slowly, being quick on the draw property poor and eachLayer covers whole carrier surface, in the time of catalysis, can not utilize completely, and utilization rate is not high.
Summary of the invention
The present invention exists thickness large for solving existing three-way catalyst, and gas diffusion is slow, and being quick on the draw property is poor and utilizeThe technical problem that rate is not high, the catalyst of provide that a kind of thickness is little, gas diffusion is slow, being quick on the draw property is poor, utilization rate is high andPreparation method.
The invention discloses a kind of three-way catalyst, taking porous ceramics as matrix, which is provided with Catalytic Layer, described Catalytic LayerComprise the first Catalytic Layer and the second Catalytic Layer; Described the first Catalytic Layer comprises the first catalysed partial and the second catalysed partial, described inThe second Catalytic Layer comprises the 3rd catalysed partial and the 4th catalysed partial; Wherein, the 3rd catalysed partial is positioned at the first catalysed partialUnder, the 4th catalysed partial be positioned at the second catalysed partial under, described the first catalysed partial is the first support oxideSupport second active noble metals with mithridatism, the second catalysed partial be Second support oxide supported there is mithridatismThree active noble metals, the 3rd catalysed partial is that the 3rd support oxide supports the 3rd active noble metals with mithridatism, the 4thCatalysed partial is that the 4th support oxide supports first active noble metals with mithridatism; Described the first support oxide,Two support oxide, the 3rd support oxide and the 4th support oxide be independently separately rare earth metal, alkaline-earth metal a kind of orSeveral oxides and activated alumina.
The preparation method who the invention also discloses a kind of this three-way catalyst, comprises the following steps:
S1, the coating feed liquid used of preparation the 3rd catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the first solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the second solution; In boehmite, add the second solution and the first solution, stir and obtain the 3rd solution; Add againThe nitrate solution of the 3rd active noble metals, mixes and makes the first coating feed liquid with ball milling method;
S2, preparation-obtained step S1 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Get ceramic matrix and put into Flat bottom container, put and vacuumize on the top of ceramic matrixDevice, controls the condition that vacuumizes, makes to apply the liquid level of feed liquid in ceramic matrix and arrives a half and stop vacuumizing;Carrier is taken out, in taking-up process, keep ceramic matrix above-below direction constant, utilize never one end of slurry of purgerBlow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 3rd catalysed partial;
S3, the coating feed liquid used of preparation the 4th catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the 4th solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the 5th solution; In boehmite, add the 5th solution and the 4th solution, stir and obtain the 6th solution; Add againThe nitrate solution of the first active noble metals, mixes and makes the second coating feed liquid with ball milling method;
S4, preparation-obtained step S3 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Ceramic matrix in step S2 is inverted in Flat bottom container, at ceramic matrixTop puts vacuum extractor, controls the condition vacuumizing, and makes to apply the liquid level of feed liquid in ceramic matrix and arrives oneHalf stops vacuumizing; By carrier take out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger fromDo not have one end of slurry to blow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th and urgeChange part;
S5, the coating feed liquid used of preparation the first catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the 7th solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the 8th solution; In boehmite, add the 8th solution and the 7th solution, stir and obtain the 9th solution; Add againThe nitrate solution of the second active noble metals, mixes and makes the 3rd coating feed liquid with ball milling method;
S6, preparation-obtained step S5 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Ceramic matrix in step S4 is inverted in Flat bottom container, at ceramic matrixTop puts vacuum extractor, controls the condition vacuumizing, and makes to apply the liquid level of feed liquid in ceramic matrix and arrives oneHalf stops vacuumizing; By carrier take out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger fromDo not have one end of slurry to blow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th and urgeChange part;
S7, the coating feed liquid used of preparation the second catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the tenth solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the 11 solution; In boehmite, add the 11 solution and the tenth solution, stir obtain the 12 moltenLiquid; Add again the nitrate solution of the 3rd active noble metals, mix and make the 4th coating feed liquid with ball milling method;
S8, preparation-obtained step S7 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Ceramic matrix in step S6 is inverted in Flat bottom container, at ceramic matrixTop puts vacuum extractor, controls the condition vacuumizing, and makes to apply the liquid level of feed liquid in ceramic matrix and arrives oneHalf stops vacuumizing; By carrier take out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger fromDo not have one end of slurry to blow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th and urgeChange part.
Three-way catalyst of the present invention only has two-layer, and the thin thickness of three-way catalyst is conducive to the diffusion of gas, has improvedReaction sensitivity, and the three-way catalyst of double-layer structure of the present invention contains four catalysed partials, the first catalysed partial andTwo catalysed partials are positioned at the first Catalytic Layer, and the 3rd catalysed partial and the 4th catalysed partial are positioned at the second Catalytic Layer, can be in catalysisTime maximum possible utilization do not have a catalysed partial, improve the utilization rate of three-way catalyst.
Brief description of the drawings
Fig. 1 is the schematic diagram of three-way catalyst of the present invention.
Detailed description of the invention
In order to make technical problem solved by the invention, technical scheme and beneficial effect clearer, below in conjunction withEmbodiment, is further elaborated to the present invention. Should be appreciated that specific embodiment described herein is only in order to explainThe present invention, is not intended to limit the present invention.
The invention discloses a kind of three-way catalyst, taking porous ceramics as matrix, which is provided with Catalytic Layer, described Catalytic LayerComprise the first Catalytic Layer and the second Catalytic Layer; Described the first Catalytic Layer comprises the first catalysed partial and the second catalysed partial, described inThe second Catalytic Layer comprises the 3rd catalysed partial and the 4th catalysed partial; Wherein, the 3rd catalysed partial is positioned at the first catalysed partialUnder, the 4th catalysed partial be positioned at the second catalysed partial under, described the first catalysed partial is the first support oxideSupport second active noble metals with mithridatism, the second catalysed partial be Second support oxide supported there is mithridatismThree active noble metals, the 3rd catalysed partial is that the 3rd support oxide supports the 3rd active noble metals with mithridatism, the 4thCatalysed partial is that the 4th support oxide supports first active noble metals with mithridatism; Described the first support oxide,Two support oxide, the 3rd support oxide and the 4th support oxide be independently separately rare earth metal, alkaline-earth metal a kind of orSeveral oxides and activated alumina.
According to three-way catalyst provided by the invention, preferably, described the first active noble metals is Rh, and the second noble metal isPt, the 3rd active noble metals is Pd. Three-way catalyst of the present invention contains three kinds of active noble metals, has reduced the use of Pt metalAmount, reduces costs. Active noble metals Rh, Pt and Pd divide out load, and Rh is more uniformly distributed at alumina layer.
According to three-way catalyst provided by the invention, for the active noble metals that makes each catalysed partial can better be sent outWave its catalytic action, preferably, the 0.05-0.2g/L that the addition of the first active noble metals Rh is ceramic matrix; The second activityThe addition of precious metals pt is the 0.05-0.2g/L of ceramic matrix, and the addition of the 3rd active noble metals Pd is ceramic matrix0.02-0.5g/L, Rh, Pt are Rh:Pt:Pd=1:1-5:1-10 with the element wt ratio of Pd.
According to three-way catalyst provided by the invention, for the active noble metals that makes each catalysed partial can better be sent outWave its catalytic action, preferably, all 5-20wt% of ceramic matrix weight not of the weight of each catalysed partial.
According to three-way catalyst provided by the invention, for the active noble metals that makes each catalysed partial can better be sent outWave its catalytic action, preferably, described the first support oxide, Second support oxide, the 3rd support oxide and the 4th yearOxide body, wherein, rare earth metal is one or more the mixing of La, Ce, Zr, Pr, Nd, Pm and Sm, alkaline-earth metal be Ba,The mixing of one or more in Mg, Ca, Sr.
According to three-way catalyst provided by the invention, for the active noble metals that makes each catalysed partial can better be sent outWave its catalytic action, preferably, described the first support oxide, Second support oxide, the 3rd support oxide and the 4th yearOxide body, rare earth metal is La, Ce, Zr, in each catalysed partial, each element wt is than being Al:Ce:Zr:La=15-70:5-30：5-30：5-20。
The present invention's ceramic matrix used is cordierite honeycomb ceramic carrier.
The present invention also provides the preparation method of this three-way catalyst, and the method comprises the following steps:
S1, the coating feed liquid used of preparation the 3rd catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the first solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the second solution; In boehmite, add the second solution and the first solution, stir and obtain the 3rd solution; Add againThe nitrate solution of the 3rd active noble metals, mixes and makes the first coating feed liquid with ball milling method;
S2, preparation-obtained step S1 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Get ceramic matrix and put into Flat bottom container, put and vacuumize on the top of ceramic matrixDevice, controls the condition that vacuumizes, makes to apply the liquid level of feed liquid in ceramic matrix and arrives a half and stop vacuumizing;Carrier is taken out, in taking-up process, keep ceramic matrix above-below direction constant, utilize never one end of slurry of purgerBlow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 3rd catalysed partial;
S3, the coating feed liquid used of preparation the 4th catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the 4th solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the 5th solution; In boehmite, add the 5th solution and the 4th solution, stir and obtain the 6th solution; Add againThe nitrate solution of the first active noble metals, mixes and makes the second coating feed liquid with ball milling method;
S4, preparation-obtained step S3 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Ceramic matrix in step S2 is inverted in Flat bottom container, at ceramic matrixTop puts vacuum extractor, controls the condition vacuumizing, and makes to apply the liquid level of feed liquid in ceramic matrix and arrives oneHalf stops vacuumizing; By carrier take out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger fromDo not have one end of slurry to blow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th and urgeChange part;
S5, the coating feed liquid used of preparation the first catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the 7th solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the 8th solution; In boehmite, add the 8th solution and the 7th solution, stir and obtain the 9th solution; Add againThe nitrate solution of the second active noble metals, mixes and makes the 3rd coating feed liquid with ball milling method;
S6, preparation-obtained step S5 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Ceramic matrix in step S4 is inverted in Flat bottom container, at ceramic matrixTop puts vacuum extractor, controls the condition vacuumizing, and makes to apply the liquid level of feed liquid in ceramic matrix and arrives oneHalf stops vacuumizing; By carrier take out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger fromDo not have one end of slurry to blow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th and urgeChange part;
S7, the coating feed liquid used of preparation the second catalysed partial: by the nitrate of rare earth metal and alkaline-earth metal, add fromSub-water, is configured to the tenth solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol mixedClose and evenly obtain the 11 solution; In boehmite, add the 11 solution and the tenth solution, stir obtain the 12 moltenLiquid; Add again the nitrate solution of the 3rd active noble metals, mix and make the 4th coating feed liquid with ball milling method;
S8, preparation-obtained step S7 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controllingIn the half position of ceramic matrix height; Ceramic matrix in step S6 is inverted in Flat bottom container, at ceramic matrixTop puts vacuum extractor, controls the condition vacuumizing, and makes to apply the liquid level of feed liquid in ceramic matrix and arrives oneHalf stops vacuumizing; By carrier take out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger fromDo not have one end of slurry to blow to the one end that has slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th and urgeChange part.
Preparation method of the present invention, the weight of described the first solution, the 4th solution, the 7th solution, the tenth solution is denseDegree is 25-55%.
Preparation method of the present invention, the pH of described the 3rd solution, the 6th solution, the 9th solution and ground 12 solution is2-5。
Preparation method of the present invention, the condition vacuumizing in described step S2, S4, S6 and S8 is: vacuum is0.08-0.2Mpa, the pumpdown time is 3-10s, and controls the sticky of the first coating feed liquid, the second coating feed liquid and the 3rd coating materialDegree is 200-2000mPa.s.
Preparation method of the present invention, described dry condition is: baking temperature 80-130 DEG C, dry 3-4 hour. InstituteThe condition of stating roasting is: sintering temperature 600-800 DEG C, roasting 4-6 hour.
Below by the structure of brief description of the drawings three-way catalyst of the present invention.
As shown in Figure 1, described three-way catalyst comprises the first Catalytic Layer 1 and the second Catalytic Layer 2, in order to be described clearly, establishesFixed the first Catalytic Layer position be " on ", the second external D score that is set as in Catalytic Layer place. The first Catalytic Layer comprises that first urgesChange part 3 and the second catalysed partial 4, the second Catalytic Layer and comprise the 3rd catalysed partial 5 and the 4th catalysed partial 6, and the 3rd urgesChange part 5 be positioned at the first catalysed partial 3 under, the 4th catalysed partial 6 be positioned at the second catalysed partial 4 under.
Below by concrete experiment several times, as example, also the present invention is described in further detail by reference to the accompanying drawings.
Embodiment 1
1, the preparation of the coating feed liquid of the 3rd catalysed partial, takes AlNO330g, makes concentration and is 30% solution100ml. Take Ce-Zr composite oxides (Shandong Zibo Hua Qing powder technology Co., Ltd) 100g, add deionized water 200g,The amount of adding PEG600 is 4g, stirs and obtains Ce-Zr mixed oxide feed liquid. Take 130g boehmite (China's AluminumIndustry limited company) add Ce-Zr mixed oxide feed liquid. The aluminum nitrate solution making before getting regulates pH value to 3. TakeConcentration is 3% Pd(NO3)2It is that in 3 feed liquid, rotational speed of ball-mill is 400r/min system that (the expensive platinum industry of grinding) solution 20ml adds pH valueObtain the coating feed liquid of the 3rd catalysed partial, controlling viscosity of sludge scope is 1000mPa.s.
2, the prepared feed liquid that contains the 3rd precious metals pd is injected and is with in graduated Flat bottom container, liquid level controlBuilt in 65mm scale; Get cordierite honeycomb ceramic carrier and put into Flat bottom container, at the top of cordierite honeycomb ceramic carrier coverUpper vacuum extractor; Suction 0.08MPa, pumpdown time 7s, makes the liquid of slurry in cordierite honeycomb ceramic carrierFace height arrives a half to be stopped vacuumizing; Carrier is taken out, and in taking-up process, catalyst above-below direction is constant, utilizes and purgesEquipment never one end of slurry is blown to the one end that has slurry, until do not have liquid to flow out; 120 DEG C are dried 4 hours, 700 DEG CRoasting 5 hours, obtains the 3rd catalysed partial.
3, prepare the coating feed liquid of the 4th catalysed partial according to the method for step 1, take concentration and be 0.5% Rh(NO3)3The technique of the feed liquid that solution 20ml contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the first noble metal Rh, controls materialFluid viscosity scope is 2000mPa.s.
4, honeycomb ceramic carrier is inverted and is come, by a side who does not apply down, the work of the feed liquid that contains Pd by coatingSkill applies the feed liquid that contains Rh, and 120 DEG C are dried 4 hours, and 700 DEG C of roastings obtain the 4th catalysed partial for 5 hours.
5, prepare the coating feed liquid of the first catalysed partial according to the method for step 1, take concentration and be 1% Pt(NO3)2MoltenThe technique of the feed liquid that liquid 20ml contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the second precious metals pt, controls feed liquidRange of viscosities is 1500mPa.s.
6, by the one end that is coated with Pd down, the technique of the feed liquid that contains Pd by coating applies the feed liquid that contains Pt, 120 DEG CDry 4 hours, 700 DEG C of roastings obtained the first catalysed partial for 5 hours.
7, prepare the coating feed liquid of the second catalysed partial according to the method for step 1, take concentration and be 1.8% Pd(NO3)2Solution 20ml, the technique of the feed liquid that contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the 3rd precious metals pd, controlsViscosity of sludge scope is 500mPa.s.
8, by the one end that is coated with Rh down, the technique of the feed liquid that contains Pd by coating applies the feed liquid that contains Pd, 120 DEG CDry 4 hours, 700 DEG C of roastings obtained the second catalysed partial for 5 hours.
Can obtain three-way catalyst A1.
Embodiment 2
1, the preparation of the coating feed liquid of the 3rd catalysed partial, takes AlNO330g, makes concentration and is 30% solution100ml. Take Ce-Zr composite oxides (Shandong Zibo Hua Qing powder technology Co., Ltd) 200g, add deionized water 300g,The amount of adding PEG600 is 6g, stirs and obtains Ce-Zr mixed oxide feed liquid. Take 150g boehmite (China's AluminumIndustry limited company) add Ce-Zr mixed oxide feed liquid. The aluminum nitrate solution making before getting regulates pH value to 5. TakeConcentration is 4% Pd(NO3)2It is that in 4 feed liquid, rotational speed of ball-mill is 300r/min system that (the expensive platinum industry of grinding) solution 40ml adds pH valueObtain the coating feed liquid of the 3rd catalysed partial, controlling viscosity of sludge scope is 200mPa.s.
2, the prepared feed liquid that contains the 3rd precious metals pd is injected and is with in graduated Flat bottom container, liquid level controlBuilt in 65mm scale; Get cordierite honeycomb ceramic carrier and put into Flat bottom container, at the top of cordierite honeycomb ceramic carrier coverUpper vacuum extractor; Suction 0.10MPa, pumpdown time 5s, makes the liquid of slurry in cordierite honeycomb ceramic carrierFace height arrives a half to be stopped vacuumizing; Carrier is taken out, and in taking-up process, catalyst above-below direction is constant, utilizes and purgesEquipment never one end of slurry is blown to the one end that has slurry, until do not have liquid to flow out; 120 DEG C are dried 4 hours, 700 DEG CRoasting 4 hours, obtains the 3rd catalysed partial.
3, prepare the coating feed liquid of the 4th catalysed partial according to the method for step 1, take concentration and be 1.0% Rh(NO3)3The technique of the feed liquid that solution 25ml contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the first noble metal Rh, controls materialFluid viscosity scope is 1000mPa.s.
4, honeycomb ceramic carrier is inverted and is come, by a side who does not apply down, the work of the feed liquid that contains Pd by coatingSkill applies the feed liquid that contains Rh, and 120 DEG C are dried 4 hours, and 700 DEG C of roastings obtain the 4th catalysed partial for 5 hours.
5, prepare the coating feed liquid of the first catalysed partial according to the method for step 1, take concentration and be 1.5% Pt(NO3)2The technique of the feed liquid that solution 30ml contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the second precious metals pt, controls materialFluid viscosity scope is 500mPa.s.
6, by the one end that is coated with Pd down, the technique of the feed liquid that contains Pd by coating applies the feed liquid that contains Pt, 120 DEG CDry 4 hours, 700 DEG C of roastings obtained the first catalysed partial for 5 hours.
7, prepare the coating feed liquid of the second catalysed partial according to the method for step 1, take concentration and be 4% solution 10ml, pressThe technique of the feed liquid that preparation contains the 3rd precious metals pd is prepared into the feed liquid that contains the 3rd precious metals pd, controls viscosity of sludge scopeFor 500mPa.s.
By the one end that is coated with Rh down, the technique of the feed liquid that contains Pd by coating applies the feed liquid that contains Pd, and 130 DEG C dryDry 3 hours, 600 DEG C of roastings obtained the second catalysed partial for 6 hours.
Can obtain three-way catalyst A2.
Embodiment 3
1, the preparation of the coating feed liquid of the 3rd catalysed partial, takes AlNO330g, makes concentration and is 30% solution100ml. Take Ce-Zr composite oxides (Shandong Zibo Hua Qing powder technology Co., Ltd) 200g, add deionized water 300g,The amount of adding PEG600 is 6g, stirs and obtains Ce-Zr mixed oxide feed liquid. Take 150g boehmite (China's AluminumIndustry limited company) add Ce-Zr mixed oxide feed liquid. The aluminum nitrate solution making before getting regulates pH value to 5. TakeConcentration is 3% Pd(NO3)2It is that in 2 feed liquid, rotational speed of ball-mill is that 300r/min makes that (the expensive platinum industry of grinding) solution 5ml adds pH valueThe coating feed liquid of the 3rd catalysed partial, controlling viscosity of sludge scope is 200mPa.s.
2, the prepared feed liquid that contains the 3rd precious metals pd is injected and is with in graduated Flat bottom container, liquid level controlBuilt in 65mm scale; Get cordierite honeycomb ceramic carrier and put into Flat bottom container, at the top of cordierite honeycomb ceramic carrier coverUpper vacuum extractor; Suction 0.20MPa, pumpdown time 3s, makes the liquid of slurry in cordierite honeycomb ceramic carrierFace height arrives a half to be stopped vacuumizing; Carrier is taken out, and in taking-up process, catalyst above-below direction is constant, utilizes and purgesEquipment never one end of slurry is blown to the one end that has slurry, until do not have liquid to flow out; 120 DEG C are dried 4 hours, 700 DEG CRoasting 4 hours, obtains the 3rd catalysed partial.
3, prepare the coating feed liquid of the 4th catalysed partial according to the method for step 1, take concentration and be 1.0% Rh(NO3)3The technique of the feed liquid that solution 25ml contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the first noble metal Rh, controls materialFluid viscosity scope is 1000mPa.s.
4, honeycomb ceramic carrier is inverted and is come, by a side who does not apply down, the work of the feed liquid that contains Pd by coatingSkill applies the feed liquid that contains Rh, and 80 DEG C are dried 4 hours, and 700 DEG C of roastings obtain the 4th catalysed partial for 5 hours.
5, prepare the coating feed liquid of the first catalysed partial according to the method for step 1, take concentration and be 1% Pt(NO3)2MoltenThe technique of the feed liquid that liquid 14ml contains the 3rd precious metals pd by preparation is prepared into the feed liquid that contains the second precious metals pt, controls feed liquidRange of viscosities is 500mPa.s.
6, by the one end that is coated with Pd down, the technique of the feed liquid that contains Pd by coating applies the feed liquid that contains Pt, 120 DEG CDry 4 hours, 700 DEG C of roastings obtained the first catalysed partial for 5 hours.
7, prepare the coating feed liquid of the second catalysed partial according to the method for step 1, take concentration and be 2% solution 5ml, pressThe technique of the feed liquid that preparation contains the 3rd precious metals pd is prepared into the feed liquid that contains the 3rd precious metals pd, controls viscosity of sludge scopeFor 500mPa.s.
By the one end that is coated with Rh down, the technique of the feed liquid that contains Pd by coating applies the feed liquid that contains Pd, and 80 DEG C dryDry 4 hours, 800 DEG C of roastings obtained the second catalysed partial for 4 hours.
Can obtain three-way catalyst A3.
Comparative example 1
Take 100g boehmite and 100gCe-Zr composite oxides, add deionized water 300ml, add PEG6004g, ball milling makes ground floor and supports the activated alumina coating material liquid of alkaline-earth metal and rare earth metal.
Take concentration and be 0.2% RhCl3 solution 100ml, take 100g boehmite and its mixed and stir.
By honeycomb ceramic carrier, dipping ground floor supports the oxygen content coating material liquid 3min of rare earth metal and alkaline-earth metal,Take out, blow through hole road with purger, 110 DEG C of dry 5h, 700 DEG C of roasting 5h apply ground floor and support rare earth metal and alkaline earthThe oxygen content of metal.
Honeycomb ceramic carrier floods the second layer and supports the oxygen content coating material liquid 3min of Rh again, takes out and blows hole, 100 DEG C of oven dry6h, 750 DEG C of roastings, are coated with and are covered with the oxygen content that supports noble metal Rh.
Take concentration and be 0.8% PtCl2 solution 150ml, get the ceramic monolith of the above-mentioned aluminium oxide that has applied Rh, dippingThis solution, 100 DEG C of dry 4h, 600 DEG C of roastings, i.e. carried noble metal Pt.
Ceramic monolith after coating Pt is impregnated into the feed liquid of the activated alumina that supports alkaline-earth metal and rare earth metalMiddle 3min, blows hole, 100 DEG C of dry 4h, and 700 DEG C of roasting 5h, obtain three-way catalyst B1.
Catalytic performance test
Adopt GB14761-1999, implant the sensor of gas analyzer at the blast pipe of catalyst rear and front end, detectGas changes through the composition before and after catalyst, calculates the conversion ratio of catalyst to CO, HC, NOx. The results are shown in Table 1.
Ageing resistace test
Adopt GB18352.3, test its ageing resistace. The results are shown in Table 1.
Table 1
。
As can be seen from Table 1, the catalytic performance of HC, the CO of the catalyst that the present invention makes before aging, NOx is good, andAfter certain condition aging, catalytic performance is still good, has embodied good ageing resistance.
Claims (11)
1. a three-way catalyst, is characterized in that, taking porous ceramics as matrix, which is provided with Catalytic Layer, described Catalytic Layer bagDraw together the first Catalytic Layer and the second Catalytic Layer; Described the first Catalytic Layer comprises the first catalysed partial and the second catalysed partial, describedTwo Catalytic Layer comprise the 3rd catalysed partial and the 4th catalysed partial; Wherein, the 3rd catalysed partial is just being positioned at the first catalysed partialBelow, the 4th catalysed partial be positioned at the second catalysed partial under, described the first catalysed partial is the first support oxide loadCarrier has the second active noble metals of mithridatism, the second catalysed partial be Second support oxide supported there is mithridatism the 3rdActive noble metals, the 3rd catalysed partial is that the 3rd support oxide supports the 3rd active noble metals with mithridatism, the 4th urgesChanging part is that the 4th support oxide supports first active noble metals with mithridatism; Described the first support oxide, secondSupport oxide, the 3rd support oxide and the 4th support oxide are independently one in rare earth metal, alkaline-earth metal, zirconium separatelyPlant or several oxide and activated aluminas; The first active noble metals is Rh, and the second noble metal is Pt, the 3rd active noble metalsFor Pd.
2. three-way catalyst according to claim 1, is characterized in that: the addition of the first active noble metals Rh is potteryThe 0.05-0.2g/L of matrix; The addition of the second active noble metals Pt is the 0.05-0.2g/L of ceramic matrix, and the 3rd is active expensiveThe addition of metal Pd is the 0.02-0.5g/L of ceramic matrix, and Rh, Pt are Rh:Pt:Pd=1:1-5 with the element wt ratio of Pd:1-10。
3. three-way catalyst according to claim 1, is characterized in that: the weight of each catalysed partial is ceramic matrixThe 5-20wt% of weight.
4. three-way catalyst according to claim 1, is characterized in that: described the first support oxide, Second support oxygenCompound, the 3rd support oxide and the 4th support oxide, wherein, rare earth metal be a kind of of La, Ce, Pr, Nd, Pm and Sm orSeveral mixing, alkaline-earth metal is one or more the mixing in Ba, Mg, Ca, Sr.
5. three-way catalyst according to claim 4, is characterized in that: described the first support oxide, Second support oxygenOxide and rare-earth oxide that compound, the 3rd support oxide and the 4th support oxide are zirconium, rare earth metal be La,Ce, in each catalysed partial, each element wt is than being Al:Ce:Zr:La=15-70:5-30:5-30:5-20.
6. according to the preparation method of three-way catalyst claimed in claim 1, it is characterized in that, comprise the following steps:
The coating feed liquid that S1, preparation the 3rd catalysed partial are used: by the nitrate of rare earth metal and alkaline-earth metal, add deionizationWater, is configured to the first solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol and mixEvenly obtain the second solution; In boehmite, add the second solution and the first solution, stir and obtain the 3rd solution; Add againThe nitrate solution of three active noble metals, mixes and makes the first coating feed liquid with ball milling method;
S2, preparation-obtained step S1 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controlling is at potteryThe half position of porcelain basal body height; Get ceramic matrix and put into Flat bottom container, put vacuum extractor on the top of ceramic matrix,The condition that control vacuumizes, makes to apply the liquid level of feed liquid in ceramic matrix and arrives a half and stop vacuumizing; To carryBody takes out, and keeps ceramic matrix above-below direction constant in taking-up process, utilize purger never one end of slurry to havingBlow in one end of slurry, until do not have liquid to flow out; Final drying, roasting prepare the 3rd catalysed partial;
The coating feed liquid that S3, preparation the 4th catalysed partial are used: by the nitrate of rare earth metal and alkaline-earth metal, add deionizationWater, is configured to the 4th solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol and mixEvenly obtain the 5th solution; In boehmite, add the 5th solution and the 4th solution, stir and obtain the 6th solution; Add againThe nitrate solution of one active noble metals, mixes and makes the second coating feed liquid with ball milling method;
S4, preparation-obtained step S3 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controlling is at potteryThe half position of porcelain basal body height; Ceramic matrix in step S2 is inverted in Flat bottom container, on the top of ceramic matrixPut vacuum extractor, control the condition vacuumizing, make to apply the liquid level of feed liquid in ceramic matrix and arrive a halfStop vacuumizing; Carrier is taken out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger neverBlow to the one end that has slurry in one end of slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th catalytic portionsPoint;
The coating feed liquid that S5, preparation the first catalysed partial are used: by the nitrate of rare earth metal and alkaline-earth metal, add deionizationWater, is configured to the 7th solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol and mixEvenly obtain the 8th solution; In boehmite, add the 8th solution and the 7th solution, stir and obtain the 9th solution; Add againThe nitrate solution of two active noble metals, mixes and makes the 3rd coating feed liquid with ball milling method;
S6, preparation-obtained step S5 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controlling is at potteryThe half position of porcelain basal body height; Ceramic matrix in step S4 is inverted in Flat bottom container, on the top of ceramic matrixPut vacuum extractor, control the condition vacuumizing, make to apply the liquid level of feed liquid in ceramic matrix and arrive a halfStop vacuumizing; Carrier is taken out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger neverBlow to the one end that has slurry in one end of slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th catalytic portionsPoint;
The coating feed liquid that S7, preparation the second catalysed partial are used: by the nitrate of rare earth metal and alkaline-earth metal, add deionizationWater, is configured to the tenth solution; Then add deionized water to the composite oxide power of rare earth metal, add polyethylene glycol and mixEvenly obtain the 11 solution; In boehmite, add the 11 solution and the tenth solution, stir and obtain the 12 solution;Add again the nitrate solution of the 3rd active noble metals, mix and make the 4th coating feed liquid with ball milling method;
S8, preparation-obtained step S7 coating feed liquid is injected and is with in graduated Flat bottom container, liquid surface height controlling is at potteryThe half position of porcelain basal body height; Ceramic matrix in step S6 is inverted in Flat bottom container, on the top of ceramic matrixPut vacuum extractor, control the condition vacuumizing, make to apply the liquid level of feed liquid in ceramic matrix and arrive a halfStop vacuumizing; Carrier is taken out, in taking-up process, keep ceramic matrix above-below direction constant, utilize purger neverBlow to the one end that has slurry in one end of slurry, until do not have liquid to flow out; Final drying, roasting prepare the 4th catalytic portionsPoint.
7. preparation method according to claim 6, is characterized in that, described the first solution, the 4th solution, the 7th solution,The weight concentration of the tenth solution is 25-55%.
8. preparation method according to claim 6, is characterized in that, described the 3rd solution, the 6th solution, the 9th solution andThe pH of the 12 solution is 2-5.
9. preparation method according to claim 6, is characterized in that, vacuumizing in described step S2, S4, S6 and S8Condition is: vacuum is 0.08-0.2Mpa, and the pumpdown time is 3-10s, and controls the first coating feed liquid, the second coating feed liquidBe 200-2000mPa.s with the viscosity of the 3rd coating material.
10. preparation method according to claim 6, is characterized in that, described dry condition is: baking temperature 80-130DEG C, dry 3-4 hour.
11. preparation methods according to claim 6, is characterized in that, the condition of described roasting is: sintering temperature 600-800 DEG C, roasting 4-6 hour.
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| KR20170115075A (en) * | 2015-02-05 | 2017-10-16 | 존슨 맛쎄이 퍼블릭 리미티드 컴파니 | Three-way catalyst |
| CN104759281B (en) * | 2015-03-11 | 2017-05-31 | 江苏大学 | A kind of preparation method of the composite oxide catalysts for purification diesel engine |
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| CN106807369B (en) * | 2017-02-13 | 2019-06-18 | 安徽新态环保科技有限公司 | A kind of automobile three-way catalysts catalyst |
| CN106807370B (en) * | 2017-03-22 | 2019-05-24 | 无锡威孚环保催化剂有限公司 | A kind of three-way catalyst |
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