CN101632930A - Catalyst for purifying automobile tail gas and preparation method thereof - Google Patents
Catalyst for purifying automobile tail gas and preparation method thereof Download PDFInfo
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- CN101632930A CN101632930A CN200810133290A CN200810133290A CN101632930A CN 101632930 A CN101632930 A CN 101632930A CN 200810133290 A CN200810133290 A CN 200810133290A CN 200810133290 A CN200810133290 A CN 200810133290A CN 101632930 A CN101632930 A CN 101632930A
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Abstract
The invention provides a catalyst for purifying automobile tail gas. The catalyst contains a carrier with a regular structure and a coating which is attached to the inner surface and/or the outer surface of the carrier with the regular structure, wherein the coating contains matrix and an active component carried on the matrix, the coating has a plurality of layers, the active component in the coating of each layer is palladium or rhodium, the coating which is directly contacted with the inner surface and/or the outer surface of the carrier with the regular structure is at the innermost layer, the active component in the coating of the innermost layer is palladium, the coating containing the active component palladium and the coating containing the active component rhodium are arranged alternately, and the total layer number of the coating is odd. The invention also provides a preparation method for the catalyst. The catalyst provided by the invention has high catalytic activity and thermal ageing resistant capacity.
Description
Technical field
The present invention relates to a kind of cleaning catalyst for tail gases of automobiles and this Preparation of catalysts method.
Background technology
In recent years, along with the progress of expanding economy and society, automobile quantity is also in increasing fast, and the emission of automobile wastes amount also increases day by day, has become the main source of atmosphere pollution.Give environment and the human harm that brings in order to control motor vehicle exhaust emission, many in the world countries have all formulated the motor vehicle exhaust emission rules of increasingly stringent.The automotive exhaust catalysis device is installed is one of most important means that vehicle exhaust is purified in the gas extraction system of vehicle exhaust, and the part that transforms with the reaction of vehicle exhaust direct chemical in the catalyst converter is a catalyst.Three unique catalytic converter is the emphasis of research as the main key technology of external control vehicle emission pollution, and it can transform three kinds of pernicious gas CO, CH, NOx in the motor vehicle emission simultaneously.
The catalytic converter that generally uses both at home and abroad is based on integral honeycomb shape structure at present, and catalyst commonly used mainly contains precious metal element, thulium and transition metals such as Pt, Pd, Rh.Because noble metal resource-constraineds such as Pt, Rh, price are high,, have a large amount of in recent years about adopting relatively cheap Pd to substitute the research of Pt, Rh for reducing its consumption.As: substitute Rh, Pt-Rh, Pt-Pd-Rh system with single Pd, Pt-Pd, Pd-Rh system.
CN1184704A discloses a kind of ternary composite metal oxide catalyst that is used for automobile exhaust gas purifying, and this catalyst comprises honeycomb ceramic carrier, and aluminum oxide coating layer and catalytic active component is characterized in that: γ-Al that the hole wall surface of honeycomb ceramic carrier adheres to
2O
3Coating contains Y
2O
3And ZrO
2The structure of described catalyst activity component is divided into two layers, and internal layer is the Ca-Ti ore type complex metal that contains precious metals pd, and is outer for containing the spinel oxides structure of precious metals pd.This catalyst is behind high temperature ageing, and the initiation temperature of catalyst is higher, and the conversion ratio of catalyst is lower.
" present Research of full Pd triple effect purification catalyst for natural gas and auto tail gas ", Sichuan University of Science ﹠ Engineering's journal (natural science edition), 2006 05 phases reported that people such as Williamson had done more detailed work to the Pd catalyst to the purification of CNG vehicle exhaust.They use precious metals pd as main active component, divide two-layer coating on ceramic honey comb or honeycomb metal carrier.Coating 1:Pd/Al
2O
3, 6g/l-250g/l, general 90g/l-150g/l, coating 2:Pd, La
2O
3, CeO
2/ Al
2O
3, CeO
2, about 14g/l, La
2O
3, 10g/l-15g/l.The labile salt of the general employing of compound, as halide, nitrate, acetate etc., 400 ℃-700 ℃ of sintering temperatures, time 1-3 hour.Available Rh partly or entirely replaces Pd in the coating 1 and 2, consumption 0.07g/l.Coating 1 and 2 is made powder respectively, adds the water mill slurry, is coated on the catalyst carrier, dry, roasting, obtain the Pd/Ce/La catalyst metering than near and all can show during poor combustion CO and HC active preferably, but undesirable to the treatment effect of NOx during with poor combustion behind high temperature ageing.
Summary of the invention
The catalytic activity that the objective of the invention is to overcome cleaning catalyst for tail gases of automobiles in the above-mentioned prior art is lower, the defective of high temperature loss of properties on aging, and cleaning catalyst for tail gases of automobiles that a kind of catalytic activity is higher, the high temperature ageing-resistant performance is good and preparation method thereof is provided.
The invention provides a kind of cleaning catalyst for tail gases of automobiles, this catalyst contains carrier with ordered structure and has the inner surface of carrier of ordered structure and/or the coating on the outer surface attached to this, described coating contains matrix and is supported on active component on the described matrix, wherein, described coating is a multilayer, active component in every layer of coating is palladium or rhodium, the coating that directly contacts with the inner surface and/or the outer surface of the carrier with ordered structure is an innermost layer, active component in the innermost layer coating is a palladium, the coating that contains active component palladium is alternately arranged with the coating that contains the active component rhodium, and total number of plies of coating is an odd number.
The present invention also provides the preparation method of described cleaning catalyst for tail gases of automobiles, this method is included on the inner surface of the carrier with ordered structure and/or the outer surface adheres to the slurry that contains matrix, dry then, roasting, and with the solution impregnation that contains soluble salts of active components, dry then, roasting, described active component is supported on the described matrix, obtain coating, wherein, described coating is a multilayer, active component in every layer of coating is palladium or rhodium, the coating that directly contacts with the inner surface and/or the outer surface of the carrier with ordered structure is an innermost layer, active component in the innermost layer coating is a palladium, and the coating that contains active component palladium is alternately arranged with the coating that contains the active component rhodium, and total number of plies of coating is an odd number.
In the catalyst provided by the invention, the coating that contains active component palladium is alternately arrangement with the coating that contains the active component rhodium, and the active component in the innermost layer coating is a precious metal palladium.Under the preferable case, described coating adopts three layers of distribution, that is, the ground floor coating contains active component palladium, and second layer coating contains the active component rhodium, and the 3rd layer of coating contains active component palladium.The present inventor finds, the coating that contains active component palladium has higher activity at low temperatures, when the coating that contains active component palladium is positioned at innermost layer, because of its good heat endurance, low temperature active can provide excellent ignition performance, more effective for the performance improvement of high temperature ageing rear catalyst; Be positioned at outermost layer and work as the coating that contains active component palladium, can further improve activity of such catalysts under the high temperature, further strengthen the high temperature resistant aging performance of catalyst, under the preferable case, in the outermost layer coating, also contain auxiliary agent, as oxide and the alkali-metal oxide of Ce and/or Zr, as the oxide of La and/or Ba with very strong oxygen storage capacity, they can play function of stabilizer, prevent γ-Al
2O
3Sintering with noble metal.In three-way catalyst provided by the invention; contain the effect that active component rhodium in the coating of rhodium mainly plays reducing NOx; add a spot of rhodium and can greatly improve the conversion ratio of NOx; but rhodium is easily poisoned; but when in making second coating, containing the active component rhodium; diffusional resistance when this design both can reduce the NOx reduction reaction as far as possible can protect rhodium not poisoned again.
In addition, in the catalyst provided by the invention, replaced the higher noble metal platinum of cost with palladium and rhodium, and the content of noble metal is few, also greatly reduces the cost of catalyst.
The specific embodiment
Cleaning catalyst for tail gases of automobiles provided by the invention contains carrier with ordered structure and has the inner surface of carrier of ordered structure and/or the coating on the outer surface attached to this, described coating contains matrix and is supported on active component on the described matrix, wherein, described coating is a multilayer, active component in every layer of coating is palladium or rhodium, the coating that directly contacts with the inner surface and/or the outer surface of the carrier with ordered structure is an innermost layer, active component in the innermost layer coating is a palladium, the coating that contains active component palladium is alternately arranged with the coating that contains the active component rhodium, and total number of plies of coating is an odd number.
According to catalyst provided by the invention, the gross weight of described coating can be preferably 30-45% for the 25-60% of vehicle weight.Volume with described carrier is a benchmark, and each content that contains palladium in the coating of active component palladium can be the 0.5-2.2 grams per liter, and the content of rhodium can be the 0.02-0.2 grams per liter in the coating of each rhodium-containing; Each contains the coating mesostroma of active component palladium and the weight ratio of active component palladium can be 1: 0.005-0.08 is preferably 1: 0.005-0.065; The coating mesostroma of each rhodium-containing and the weight ratio of active component rhodium can be 1: 0.001-0.01 is preferably 100: 0.001-0.006.
According to catalyst provided by the invention, under the preferable case, the number of described coating is three layers, and the innermost layer coating from inside to outside and the weight ratio of carrier are 0.09-0.31: 1, the weight ratio 0.06-0.31 of intermediate layer and carrier: 1, the weight ratio of outermost layer and carrier is 0.06-0.30: 1.The active component that is supported on the described matrix in described three layers of coating from inside to outside is followed successively by palladium, rhodium and palladium.
According to catalyst provided by the invention, under the preferable case, also contain auxiliary agent in the described coating of one deck at least, described auxiliary agent be for can play function of stabilizer, with the various materials of the sintering that prevents matrix and noble metal.
According to the present invention, under the preferable case, described auxiliary agent can be selected from the oxide and in the VIII family non-noble metal oxide one or more of oxide, the rare earth metal of oxide, the VIIB family metal of oxide, the group vib metal of oxide, the VB family metal of oxide, the NB family metal of oxide, the IIB family metal of oxide, the IB family metal of IIA family metal, more preferably is selected from the oxide of La, Ce, Pr, Nd, Sm, Eu, Gd, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mg, K, Ca, Sr and Ba one or more; The adjustable extent broad of the weight ratio of described auxiliary agent and matrix, under the preferable case, the weight ratio of described auxiliary agent and matrix is 0.25-1.5: 1,0.42-1 more preferably: 1.The amount of described auxiliary agent is all total contents that contains auxiliary agent in the coating of auxiliary agent, and the amount of described matrix is the total content of all coating mesostromas.
Described matrix can be various refractory oxides, for example can be selected from aluminium oxide, silica, amorphous silicon aluminium, titanium oxide, boron oxide and cerium-zirconium-aluminium composite oxide one or more.According to catalyst provided by the invention, described matrix is preferably aluminium oxide and/or cerium-zirconium-aluminium composite oxide, and the kind of described aluminium oxide is conventionally known to one of skill in the art, as being γ-Al
2O
3Described matrix can be commercially available, and also can prepare according to the method for well known to a person skilled in the art.
The carrier of ordered structure of the present invention is meant the catalyst carrier of regular parallel duct of the hollow with macro-scale and structured surface.The example of the carrier of described ordered structure includes but not limited to one or more in cordierite honeycomb carrier, mullite honeycomb substrate, cellular alumina carrier and the metal alloy honeycomb substrate.The example of described metal alloy honeycomb substrate comprises the Fe-Cr-Al alloy cellular carrier.
The preparation method of cleaning catalyst for tail gases of automobiles provided by the invention is included on the inner surface of the carrier with ordered structure and/or the outer surface and adheres to the slurry that contains matrix, dry then, roasting, and with the solution impregnation that contains soluble salts of active components, dry then, roasting, described active component is supported on the described matrix, obtain coating, wherein, described coating is a multilayer, active component in every layer of coating is palladium or rhodium, the coating that directly contacts with the inner surface and/or the outer surface of the carrier with ordered structure is an innermost layer, active component in the innermost layer coating is a palladium, the coating that contains active component palladium is alternately arranged with the coating that contains the active component rhodium, and total number of plies of coating is an odd number.
According to preparation method provided by the invention, the consumption of described slurry makes the gross weight of coating be preferably 30-55% for the 25-60% of vehicle weight.Volume with described carrier is a benchmark, and each content that contains palladium in the coating of active component palladium can be the 0.5-2.2 grams per liter, and the content of rhodium can be the 0.02-0.2 grams per liter in the coating of each rhodium-containing; Each contains the coating mesostroma of active component palladium and the weight ratio of active component palladium can be 1: 0.005-0.08 is preferably 1: 0.005-0.065; The coating mesostroma of each rhodium-containing and the weight ratio of active component rhodium can be 1: 0.001-0.01 is preferably 100: 0.001-0.006.
According to preparation method provided by the invention, under the preferable case, the presoma that can also contain auxiliary agent and/or auxiliary agent in the described slurry that contains matrix, and/or the solution that contains soluble salts of active components can also contain the presoma of auxiliary agent and/or auxiliary agent, described auxiliary agent is selected from IIA family metal, IB family metal, IIB family metal, NB family metal, VB family metal, the group vib metal, VIIB family metal, in the non-noble metal oxide of rare earth metal and VIII family one or more, the presoma of described auxiliary agent is selected from IIA family metal, IB family metal, IIB family metal, NB family metal, VB family metal, the group vib metal, VIIB family metal, in the non-noble metal soluble-salt of rare earth metal and VIII family one or more, the consumption of the presoma of described auxiliary agent and/or auxiliary agent is not particularly limited, under the preferable case, the consumption of the presoma of described auxiliary agent and/or auxiliary agent makes in the catalyst that obtains, the weight ratio of auxiliary agent and matrix is 0.20-1.8: 1, be preferably 0.54-1.5: 1.Metal in described auxiliary agent or the auxiliary agent presoma is preferably selected from one or more among La, Ce, Pr, Nd, Sm, Eu, Gd, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mg, Ca, Sr and the Ba.
The addition manner of described auxiliary agent and/or auxiliary agent presoma is conventionally known to one of skill in the art, for example, when preparation contains the slurry of matrix, auxiliary agent directly can be mixed with the slurry that contains matrix; After forming pulp layer, when containing the soluble salts of active components solution impregnation and contain the carrier of matrix, can also with the presoma of auxiliary agent with contain soluble salts of active components solution and mix the mixing that obtains and flood easily.
The presoma of described auxiliary agent can be various water-soluble salt, for example one or more in nitrate, acetate, hydrochloride, oxalates, malate and the tartrate.
The described preparation method who contains the slurry of matrix is conventionally known to one of skill in the art, for example, matrix and water mixed, and ball milling, being prepared into solid content is 10-60 weight %, is preferably the slurry of 30-50 weight %.Under the preferable case, can also in this contains the slurry of matrix, add aluminum nitrate, boehmite and polyethylene glycol and mix; The consumption of described aluminum nitrate, boehmite and polyethylene glycol is not particularly limited, and for example, the weight ratio of described matrix and described aluminum nitrate, boehmite and polyethylene glycol can be 1: 0.05-0.5: 0.05-0.5: 0.01-0.1.Metal ion also has the effect of the catalysis of helping in the described aluminum nitrate, can further consolidate the catalytic effect that helps of auxiliary agent; Present certain acidity in the aluminum nitrate, can regulate the pH value of slurry that forms coating, make the slurry that contains matrix be faintly acid, thereby make the modest viscosity of slurry under weakly acidic influence, such slurry coating realizes that easily disposable amount is many and good with the adhesion of carrier to carrier.
Described boehmite (Al (OH)
3) play into the glue effect.
Described polyethylene glycol mainly is a surfactant, plays the effect of pore-creating, after the roasting, improves the quantity and the size of coating mesopore, is convenient to coating, can improve coating's adhesion and performance.
When described matrix is aluminium oxide, can also in containing the slurry of matrix, add hydrogen-storing material cerium-zirconium mixed oxide as auxiliary agent, play when tail gas atmosphere and store oxygen during for oxidizing atmosphere, during reducing atmosphere, discharge the effect of oxygen, the weight ratio of described alumina support and cerium-zirconium mixed oxide is not particularly limited, and can be 1-5: 1.
The composition that forms the slurry that contains matrix of different coating can be the same or different, and main difference corresponding to cerium-zirconium mixed oxide relative amount in the slurry: cerium-zirconium mixed oxide content is high relatively, more can be high temperature resistant; Cerium-zirconium mixed oxide content is low relatively, and its ignition is better, can regulate the relative amount of cerium-zirconium mixed oxide in the slurry as required.
The method according to this invention, the method of adhering to the slurry that contains matrix on the inner surface of the carrier with ordered structure and/or outer surface can adopt and well known to a person skilled in the art the whole bag of tricks, as, the slurry that contains matrix can be coated on the inner surface and/or outer surface of carrier, and/or the carrier impregnation that will have an ordered structure is in the described slurry that contains matrix with ordered structure.The amount that applies can be selected according to actual needs, and the time of dipping and number of times also can be controlled by the adhesion amount of actual needs.
When the carrier that contains pulp layer immersed in the solution that contains soluble salts of active components, the condition of dipping can make dipping back active component only support and be evenly distributed on this layer pulp layer.
The concentration adjustable extent broad of described soluble salts of active components solution can be 2-5 weight % usually, and described soluble salts of active components can be in nitrate, hydrochloride and the acetate one or more.Dip time be as long as guaranteeing maceration extract can all be adsorbed, and active component only supported and be evenly distributed on this layer pulp layer and get final product, and the time of described dipping can be 2-10 minute, is preferably 3-6 minute.
According to Preparation of catalysts method of the present invention, this method also is included in adheres on the inner surface of the carrier with ordered structure and/or the outer surface behind the slurry that contains matrix and/or with the step of the drying after the solution impregnation that contains soluble salts of active components, roasting, the method of described drying, roasting and condition are conventionally known to one of skill in the art, as, described drying can be one or more in air dry, vacuum drying, the forced air drying, the temperature of described drying can be 30-200 ℃, is preferably 50-150 ℃.The temperature of described roasting can be 450-800 ℃, and the time of roasting can be 1-6 hour.
Under the preferable case, stop up, after method of the present invention also comprises the dip coating slurries, blow the step of logical matrix inner duct with compressed air for avoiding applying back ceramic matrix inner duct.The time of dipping is not particularly limited, and can control the time of dipping and the number of times of dipping according to needed coating weight.
Adopt the mode of embodiment that the present invention is explained in further detail below.
The used catalyst carrier of the present invention is: cordierite honeycomb ceramic;
Specification is: 101.6 millimeters * 123.3 millimeters of Φ, and volume is 1 liter, and weight is 480 grams, and the order number is 400 orders;
Matrix cerium-zirconium-aluminium composite oxide: Zibo Huaqing Powder Material Techn Co., Ltd. buys;
Matrix γ-Al
2O
3: Zibo Huaqing Powder Material Techn Co., Ltd. buys;
The auxiliary agent cerium-zirconium mixed oxide: Zibo Huaqing Powder Material Techn Co., Ltd. buys.
Embodiment 1
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
(1) preparation of coating paste: with 150 gram γ-Al
2O
3, 150 gram cerium-zirconium mixed oxides, 30 gram boehmites, 30 gram aluminum nitrates, 8 gram polyethylene glycol and 550 restrain water and mix, ball milling obtained first slurry that solid content is 36 weight % in 4 hours;
With 200 gram γ-Al
2O
3, 100 gram cerium-zirconium mixed oxides, 30 gram boehmites, 30 gram aluminum nitrates, 8 gram polyethylene glycol and 550 restrain water and mix, ball milling obtained second slurry that solid content is 36 weight % in 4 hours;
(2) cordierite honeycomb ceramic carrier be impregnated in above-mentioned first slurry, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of first pulp layer; The time of dipping and number of times make that the weight of first pulp layer is that 50 grams (wherein contain γ-Al after the roasting
2O
3Matrix 23 grams; Auxiliary agent cerium-zirconium mixed oxide 23 grams);
(3) catalyst carrier that step (2) is obtained impregnated in 3.25 gram palladium nitrates, 15 gram barium nitrates mixed in the mixed solution that obtains 4 minutes with 150 gram water, and after the taking-up, drying is 4 hours under 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains first coating; After the roasting in this first coating barytic weight be 8.8 the gram, the weight of Metal Palladium be 1.5 the gram; The gross weight of first coating is 60.3 grams;
(4) catalyst carrier that step (3) is obtained impregnated in first slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of second pulp layer, it is that 70 grams (wherein contain γ-Al that the time of dipping and number of times make the weight of second pulp layer that obtains
2O
3Matrix 32 grams; Auxiliary agent cerium-zirconium mixed oxide 32 grams); Once more this carrier impregnation is mixed in the aqueous solution that obtains with 100 gram water in containing 30 gram zirconium nitrates, after the taking-up, descended drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the zirconic weight that this second pulp layer contains after the roasting is 10.9 grams;
(5) catalyst carrier that step (4) is obtained impregnated in and contains 0.33 gram rhodium nitrate and mixed in the mixed solution that obtains 4 minutes with 150 gram water, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains second coating; The weight of the rhodium that this second coating contains after the roasting is 0.15 gram; The gross weight of second coating is 81.05 grams;
(6) catalyst matrix that step (5) is obtained impregnated in second slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; It is that 60 grams (wherein contain γ-Al that the time of dipping and number of times make the weight of the 3rd pulp layer that obtains
2O
3Matrix 36.6 grams; Auxiliary agent cerium-zirconium mixed oxide 18.3 grams); Once more this carrier impregnation is restrained lanthanum nitrate (La (NO in containing 30
3)
36H
2O) mixes in the aqueous solution that obtains with 100 gram water, after the taking-up, 110 ℃ of following dryings 4 hours, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the weight of the 3rd lanthana that pulp layer contains is 11.3 grams after the roasting;
(7) catalyst matrix that step (6) is obtained impregnated in 1.08 gram palladium nitrates and mixed in the mixed solution that obtains 5 minutes with 150 gram water, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of the 3rd coating, the weight of the palladium that the 3rd coating contains is 0.5 gram, and the gross weight of the 3rd coating is 71.8 grams.Obtain catalyst A.
Embodiment 2
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
Method according to embodiment 1 prepares catalyst, and different is, is used for the mixed aqueous solution of impregnated carrier in step (3), and the consumption of palladium nitrate is 1.08 grams, and the weight of the Metal Palladium that this first coating contains after the roasting is 0.5 gram; The gross weight of first coating is 59.3 grams; The mixed aqueous solution that is used for impregnated carrier in step (7), the consumption of palladium nitrate are 3.25 grams, and the weight of the palladium that the 3rd coating contains after the roasting is 1.5 grams; The gross weight of the 3rd coating is 72.8 grams.Obtain catalyst B.
Embodiment 3
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
Method according to embodiment 1 prepares catalyst, and different is, is used for the mixed aqueous solution of impregnated carrier in step (3), and the consumption of palladium nitrate is 2.17 grams, and the weight of the Metal Palladium that contains in first coating after the roasting is 1 gram; The gross weight of first coating is 59.8 grams; The mixed aqueous solution that is used for impregnated carrier in step (7), the consumption of palladium nitrate are 2.17 grams, and the weight of the Metal Palladium that the 3rd coating contains after the roasting is 1 gram; The gross weight of the 3rd coating that obtains is 72.3 grams.Obtain catalyst C.
Embodiment 4
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
(1) preparation of coating paste: 250 gram cerium-zirconium-aluminium composite oxides, 50 gram cerium-zirconium mixed oxides, 30 gram boehmites, 30 gram aluminum nitrates, 8 gram polyethylene glycol are mixed with 550 gram water, and ball milling obtained first slurry that solid content is 36 weight % in 4 hours;
With 195 gram γ-Al
2O
3, 150 gram cerium-zirconium mixed oxides, 30 gram boehmites, 30 gram aluminum nitrates, 8 gram polyethylene glycol and 550 restrain water and mix, ball milling obtained second slurry that solid content is 39 weight % in 4 hours;
(2) cordierite honeycomb ceramic carrier be impregnated in first slurry that step (1) obtains, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of first pulp layer; The time of dipping and number of times make that the weight of first pulp layer is 80 grams, (wherein contain matrix cerium-zirconium-aluminium composite oxide 61.25 grams; Auxiliary agent cerium-zirconium mixed oxide 12.32 grams);
(3) carrier impregnation that step (2) is obtained was mixed in the mixed solution that obtains 4-5 minute with 150 gram water in 4.33 gram palladium nitrates, 20 gram lanthanum nitrates, and after the taking-up, drying is 4 hours under 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains first coating; The weight of the lanthana that this first coating contains after the roasting is that the weight of 7.5 grams, Metal Palladium is 2 grams; Gross weight 89.5 grams of first coating;
(4) catalyst carrier that step (3) is obtained impregnated in first slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Once more this carrier impregnation is mixed in the aqueous solution that obtains with 100 gram water in containing 30 gram zirconium nitrates, after the taking-up, descended drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of second pulp layer; The time of dipping and number of times make that the weight of second pulp layer is 85.9 grams (amount 57.3 grams that wherein contain matrix cerium-zirconium-aluminium composite oxide; Auxiliary agent cerium-zirconium mixed oxide 11.5 grams; Zirconia 10.9 grams);
(5) catalyst carrier that step (4) is obtained impregnated in and contains 0.18 gram rhodium nitrate and mixed in the mixed solution that obtains 4-5 minute with 150 gram water, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains second coating; The weight of the rhodium that this second coating contains after the roasting is 0.08 gram; Total augment weight 85.98 grams of second coating;
(6) catalyst matrix that step (5) is obtained impregnated in second slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the weight of the 3rd pulp layer is that 70 grams (wherein contain matrix γ-Al
2O
350 grams, auxiliary agent cerium-zirconium mixed oxide 12.9 grams); Once more this carrier impregnation is mixed in the aqueous solution that obtains with 100 gram water in containing 39.8 gram lanthanum nitrates, after the taking-up, descended drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the weight of the 3rd lanthana that pulp layer contains is 15 grams after the roasting;
(7) catalyst carrier that step (6) is obtained impregnated in 1.08 gram palladium nitrates and mixed in the mixed solution that obtains 4-5 minute with 150 gram water, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the carrier of the 3rd coating after the roasting, the weight of the Metal Palladium that the 3rd coating contains is 0.5 gram, and the gross weight of the 3rd coating is 85.5 grams.Obtain catalyst D.
Embodiment 5
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
Method according to embodiment 4 prepares catalyst, and different is, is used for the mixed aqueous solution of impregnated carrier in step (3), and the consumption of palladium nitrate is 1.08 grams, and the weight of the Metal Palladium that first coating contains after the roasting is 0.5 gram; The gross weight of first coating is 88 grams; The mixed aqueous solution that is used for impregnated carrier in step (7), the consumption of palladium nitrate are 4.33 grams; The 3rd weight that is coated with the Metal Palladium that contains that obtains after the roasting is 2 grams, and the total heavy of the 3rd coating is 87 grams.Obtain catalyst E.
Embodiment 6
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
Method according to embodiment 4 prepares catalyst, and different is, is used for the mixed aqueous solution of impregnated carrier in step (3), and the consumption of palladium nitrate is 2.17 grams, and the weight of the Metal Palladium that first coating contains after the roasting is 1 gram; The gross weight of first coating is 88.5 grams; The mixed aqueous solution that is used for impregnated carrier in step (7), the consumption of palladium nitrate are 2.17 grams, and the weight of the Metal Palladium that the 3rd coating contains after the roasting is 1 gram; The gross weight of the 3rd coating is 86 grams.Obtain catalyst F.
Embodiment 7
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
Method according to embodiment 1 prepares catalyst, and different is, the time of dipping and number of times make that the weight of first pulp layer is that 35 grams (wherein contain γ-Al after the roasting
2O
3Matrix 16 grams; Auxiliary agent cerium-zirconium mixed oxide 16 grams); Then, with this catalyst carrier impregnated in 2.17 gram palladium nitrates, 8.52 gram barium nitrates mixed in the mixed solution that obtains 5 minutes with 150 gram water, after the taking-up, drying is 4 hours under 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains first coating; The barytic weight that this first coating contains after the roasting is that the weight of 5 grams, Metal Palladium is 1 gram; The gross weight of first coating is 41 grams;
Said catalyst carrier be impregnated in first slurry that embodiment 1 step (1) obtains, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst matrix of second pulp layer, it is that 40 grams (wherein contain matrix γ-Al that the time of dipping and number of times make the weight of second pulp layer that obtains
2O
3Carrier 18 .3 gram; Auxiliary agent cerium-zirconium mixed oxide 18.3 grams); Once more this carrier impregnation is mixed in the aqueous solution that obtains with 100 gram water in containing 16.5 gram zirconium nitrates, after the taking-up, descended drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the zirconic weight that this second pulp layer contains after the roasting is 6 grams;
The above-mentioned catalyst carrier that obtains be impregnated in contain 0.22 gram rhodium nitrate and mixed in the mixed solution that obtains 4 minutes with 150 gram water, after the taking-up, descended drying 4 hours at 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst matrix that contains second coating; The weight of the rhodium that this second coating contains after the roasting is 0.1 gram; The gross weight of second coating is 46.1 grams;
The above-mentioned catalyst carrier that obtains be impregnated in second slurry that embodiment 1 step (1) obtains, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; It is that 45 grams (wherein contain γ-Al that the time of dipping and number of times make the weightening finish of the 3rd pulp layer that obtains
2O
3Matrix 27.6 grams; Auxiliary agent cerium-zirconium mixed oxide 13.8 grams); Once more this carrier impregnation is restrained lanthanum nitrate (La (NO in containing 14.1
3)
36H
2O), 9 gram barium nitrates mix in the aqueous solution that obtains with 100 gram water, after the taking-up, descend drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the weight of the 3rd lanthana that pulp layer contains is 5.3 grams after the roasting, and barytic weight is 3.8 grams;
The above-mentioned catalyst carrier that obtains be impregnated in 2.17 gram palladium nitrates mixed in the mixed solution that obtains 4 minutes with 150 gram water, after the taking-up, descended drying 4 hours at 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of the 3rd coating after the roasting, the weight of the palladium that contains in the 3rd coating of this carrier is 1 gram, and the gross weight of the 3rd coating is 55.1 grams;
Said catalyst carrier be impregnated in first slurry that embodiment 1 step (1) obtains, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst matrix of the 4th pulp layer, it is that 30 grams (wherein contain γ-Al that the time of dipping and number of times make the weight of the 4th pulp layer that obtains
2O
3Matrix 13.8 grams; Auxiliary agent cerium-zirconium mixed oxide 13.8 grams); Once more this carrier impregnation is mixed in the aqueous solution that obtains with 100 gram water in containing 13.5 gram zirconium nitrates, after the taking-up, descended drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make after the roasting that the zirconic amount that the 4th pulp layer contains is 4.9 grams;
The above-mentioned catalyst carrier that obtains be impregnated in contain 0.11 gram rhodium nitrate and mixed in the mixed solution that obtains 4 minutes with 150 gram water, after the taking-up, descended drying 4 hours at 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains the 4th coating; The weight of the rhodium that the 4th coating contains after the roasting is 0.05 gram; The gross weight of the 4th coating is 34.95 grams;
The above-mentioned catalyst carrier that obtains be impregnated in second slurry that embodiment 1 step (1) obtains, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; It is that 30 grams (wherein contain γ-Al that the time of dipping and number of times make the weight of the 5th pulp layer that obtains
2O
3Matrix 18.4 grams; Auxiliary agent cerium-zirconium mixed oxide 9.2 grams); Once more this carrier impregnation is restrained lanthanum nitrate (La (NO in containing 15.9
3)
36H
2O) mixes in the aqueous solution that obtains with 100 gram water, after the taking-up, 110 ℃ of following dryings 4 hours, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the weight of the 5th lanthana that pulp layer contains is 6 grams after the roasting;
The above-mentioned catalyst carrier that obtains be impregnated in 2.17 gram palladium nitrates mixed in the mixed solution that obtains 5 minutes with 150 gram water, after the taking-up, descended drying 4 hours at 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of the 5th coating after the roasting, the weight of the 5th palladium that coating contains is 1 gram, and the gross weight of the 5th coating is 37 grams.Obtain catalyst G.
Embodiment 8
This embodiment is used to illustrate the preparation of cleaning catalyst for tail gases of automobiles provided by the invention
Method according to embodiment 1 prepares catalyst, and different is, in step (2), cordierite honeycomb ceramic carrier be impregnated in above-mentioned first slurry, after the taking-up, blow the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of first pulp layer; The time of dipping and number of times make that the weight of first pulp layer is that 40 grams (wherein contain γ-Al after the roasting
2O
3Matrix 18.3 grams; Auxiliary agent cerium-zirconium mixed oxide 18.3 grams);
(3) catalyst carrier that step (2) is obtained impregnated in 2.6 gram palladium nitrates, 11.6 gram barium nitrates mixed in the mixed solution that obtains 5 minutes with 150 gram water, and after the taking-up, drying is 4 hours under 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains first coating; The barytic weight that this first coating contains after the roasting is that the weight of 6.8 grams, Metal Palladium is 1.2 grams; The gross weight of first coating is 48 grams;
(4) catalyst carrier that step (3) is obtained impregnated in first slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of second pulp layer, it is that 50 grams (wherein contain γ-Al that the time of dipping and number of times make the weight of second pulp layer that obtains
2O
3Matrix 23 grams; Auxiliary agent cerium-zirconium mixed oxide 23 grams); Once more this carrier impregnation is mixed in the aqueous solution that obtains with 100 gram water in containing 19.3 gram zirconium nitrates, after the taking-up, descended drying 4 hours at 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the zirconic amount that this second pulp layer contains after the roasting is 7 grams;
(5) catalyst carrier that step (4) is obtained impregnated in and contains 0.33 gram rhodium nitrate and mixed in the mixed solution that obtains 4.5 minutes with 150 gram water, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst carrier that contains second coating; The weight of the rhodium that this second coating contains after the roasting is 0.1 gram; The gross weight of second coating is 57.1 grams;
(6) catalyst carrier that step (5) is obtained impregnated in second slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; It is that 50 grams (wherein contain γ-Al that the time of dipping and number of times make the weight of the 3rd pulp layer that obtains
2O
3Matrix 30.6 grams; Auxiliary agent cerium-zirconium mixed oxide 15.3 grams); Once more this carrier impregnation is restrained lanthanum nitrate (La (NO in containing 22
3)
36H
2O) mixes in the aqueous solution that obtains with 100 gram water, after the taking-up, 110 ℃ of following dryings 4 hours, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the weight of the 3rd lanthana that pulp layer contains is 8.3 grams after the roasting;
(7) catalyst carrier that step (6) is obtained impregnated in 1.73 gram palladium nitrates and mixed in the mixed solution that obtains 5 minutes with 150 gram water, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of the 3rd coating after the roasting, the weight of the palladium that the 3rd coating contains is 0.8 gram, and the gross weight of the 3rd coating is 59.1 grams.Obtain catalyst H.
Comparative Examples 1
This Comparative Examples is used to illustrate the preparation of reference catalyst
(1) preparation of coating paste: with 150 gram γ-Al
2O
3, 150 gram cerium-zirconium mixed oxides, 30 gram boehmites, 30 gram aluminum nitrates, 8 gram polyvinyl alcohol and 550 restrain water and mix, ball milling obtained the slurry that solid content is 36 weight % in 4 hours;
(2) cordierite honeycomb ceramic carrier be impregnated in the slurry that step (1) obtains, after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Obtain containing the catalyst carrier of first pulp layer; The time of dipping and number of times make that the weight of first pulp layer is 90 grams;
(3) carrier impregnation that step (2) is obtained was mixed in the mixed solution that obtains 4 minutes with 150 gram water in 4.33 gram palladium nitrates, 15 gram barium nitrates, and after the taking-up, drying is 4 hours under 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; Make the catalyst matrix that contains first coating; The weight of the palladium that this first coating contains after the roasting is 2 grams, and barytic weight is 8.8 grams; The gross weight of first coating is 100.8 grams;
(4) catalyst carrier that step (3) is obtained impregnated in the slurry that step (1) obtains, and after the taking-up, blows the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Dip time and number of times make that the weight of second pulp layer is 90 grams; Once more this matrix be impregnated in and contain 30 gram zirconium nitrate (Zr (NO
3)
33H
2O) mixes in the aqueous solution that obtains with 100 gram water, after the taking-up, 110 ℃ of following dryings 4 hours, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the zirconic weight that this second pulp layer contains after the roasting is 10.9 grams;
(5) catalyst carrier that step (4) is obtained impregnated in and contains 0.33 gram rhodium nitrate and 150 and restrain water and mixed in the mixed solution that obtains 4 minutes, after the taking-up, drying is 4 hours under 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace, obtain containing the catalyst carrier of this second coating after the roasting, the weight of the rhodium that this coating contains is 0.15 gram; The gross weight of second coating is 101.1 grams.Obtain reference catalyst a.
Comparative Examples 2
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 1 prepares reference catalyst, different is, the catalyst carrier that contains first pulp layer that step (2) is obtained impregnated in and contains 0.33 gram rhodium nitrate, 15 gram barium nitrates and 150 and restrain water and mixed in the mixed solution that obtains 4 minutes, after the taking-up, 100 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace, obtain containing the catalyst carrier of first coating after the roasting, the weight of the rhodium that this coating contains is 0.15 gram, and barytic weight is 8.8 grams; The gross weight of first coating is 98.95 grams;
In step (4), this catalyst carrier be impregnated in the slurry that Comparative Examples 1 step (1) obtains, after the taking-up, blow the through hole road with compressed air, put into drying box 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; Dip time and number of times make that the weight of second pulp layer is 90 grams; Once more this carrier impregnation is restrained zirconium nitrate (Zr (NO in containing 30
3)
33H
2O) and in the aqueous solution of 100 gram water, after the taking-up, 110 ℃ dry 4 hours down, 600 ℃ of following roastings are 4 hours in Muffle furnace; The time of dipping and number of times make that the catalyst carrier that obtains containing second coating after the roasting, the zirconic weight that this coating contains are 10.9 grams;
In step (5), the carrier impregnation that obtains was mixed with 150 gram water in the mixed solution that obtains 4 minutes in 4.33 gram palladium nitrates, take out back drying 4 hours under 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The catalyst carrier that contains second coating after the roasting, the amount of the palladium that this coating contains are 2 grams, and the gross weight of second coating is 102.9 grams.Obtain reference catalyst b.
Comparative Examples 3
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 1 prepares reference catalyst, and different is, the weight that in step (2) time and the number of times of the dipping of cordierite honeycomb ceramic carrier in slurries is made the pulp layer of winning is 150 grams;
In step (3), the catalyst carrier that will contain first pulp layer impregnated in once more contain 30 gram zirconium nitrates, 15 gram lanthanum nitrates mix in the aqueous solution that obtains with 150 gram water, after the taking-up, drying is 4 hours under 110 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace; The zirconic weight that the time of dipping and number of times make first pulp layer contain is 10.9 grams, weight 5.6 grams of lanthana;
In step (4), an end of the carrier that step (3) is obtained impregnated in and contains 4.33 gram palladium nitrates and mixed with 70 gram water in the mixed solution that obtains 3.5 minutes, after the taking-up, descends drying 4 hours at 100 ℃, and 600 ℃ of following roastings are 4 hours in Muffle furnace; The amount of the palladium that this first pulp layer contains after the roasting is 2 grams; The other end of this carrier be impregnated in contain 0.33 gram rhodium nitrate and 70 and restrain water and mixed in the mixed solution that obtains 3.5 minutes, after the taking-up, drying is 4 hours under 100 ℃, 600 ℃ of following roastings are 4 hours in Muffle furnace, the weight of the rhodium that this first pulp layer contains after the roasting is 0.15 gram, and the gross weight of first coating that obtains is 168.65 grams.Obtain reference catalyst c.
Comparative Examples 4
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 1 prepares reference catalyst, different is, form first slurry of slurry that first pulp layer adopts, form second slurry of slurry that second pulp layer adopted, obtain reference catalyst d for preparing among the embodiment 4 for preparing among the embodiment 4.
Comparative Examples 5
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 2 prepares reference catalyst, different is, form first slurry of slurry that first pulp layer adopts, form second slurry of slurry that second pulp layer adopted, obtain reference catalyst e for preparing among the embodiment 4 for preparing among the embodiment 4.
Comparative Examples 6
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 3 prepares reference catalyst, and different is that forming the slurry that pulp layer adopted is first slurry of preparation among the embodiment 4, obtains reference catalyst f.
Comparative Examples 7
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 1 prepares reference catalyst, and different is, on first pulp layer during the dipping active component, while palladium-impregnated and rhodium, dip time is 4 minutes, contains rhodium nitrate 0.11 gram in the maceration extract, the weight of the rhodium that first coating contains is 0.05 gram, obtains reference catalyst g.
Comparative Examples 8
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 1 prepares reference catalyst, and different is, on second pulp layer during the dipping active component, while palladium-impregnated and rhodium, dip time is 4 minutes, contains rhodium nitrate 0.11 gram in the maceration extract, the weight of the rhodium that second coating contains is 0.05 gram, obtains reference catalyst h.
Comparative Examples 9
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to Comparative Examples 1 prepares reference catalyst, different is, on first pulp layer and second pulp layer during the dipping active component, while palladium-impregnated and rhodium, when preparation first coating, contain rhodium nitrate 0.22 gram in the maceration extract, dip time is 4 minutes, and the weight of the rhodium that first coating contains is 0.1 gram; When preparation second coating, contain rhodium nitrate 0.22 gram in the maceration extract, dip time is 4 minutes, the weight of the rhodium that second coating contains is 0.1 gram, obtains reference catalyst i.
Comparative Examples 10
This Comparative Examples is used to illustrate the preparation of reference catalyst
Method according to the disclosed embodiment of CN1184704A prepares reference catalyst j.
Embodiment 9-16
This embodiment is used to illustrate the evaluation of the catalytic activity and the ageing resistace of catalyst
Laboratory simulation tail gas is HC (C
3H
8): 1800ppm, CO:2.46 volume %, NOx:1500ppm, all the other are nitrogen, nitrogen is protection gas: control N voluntarily
2And O
2Flow make λ=1 (λ is an air-fuel ratio), or change in very among a small circle in λ=1 front and back, unaged experiment condition: air speed is 6 * 10
4h
-1, 400 ℃ of reaction temperatures.The catalyst of test implementation example 1-8 is to the initiation temperature T of HC, CO, NOx
50, and the catalyst of test after wearing out in 4 hours 1000 ℃ of following roastings is to the initiation temperature T of HC, CO, NOx
50, the reaction temperature of test fresh sample and aged samples conversion ratio is 400 ℃, testing procedure is as follows:
1, with in the exhaust analyzer test simulation tail gas, under the situation of not adorning catalyst, the initial concentration value of record HC, CO, NOx is designated as C
0Represent the numerical value of CO, NO, HC respectively.
2, catalyst carrier is put into quartz tube reactor, by quartz ampoule, control quartz ampoule temperature is 400 ℃, and control N with simulated exhaust gas
2And O
2Flow make λ=1 (λ is an air-fuel ratio), or change in very among a small circle in λ=1 front and back, activate after 30 minutes, after record passed through catalyst action, the concentration value of CO, NO, HC was designated as C
1Represent the numerical value of CO, NO, HC respectively;
And according to following formula calculating conversion ratio;
η (conversion ratio) %=((C
0-C
1)/C
0) * 100%
The result is as shown in table 1.
Comparative Examples 11-20
This Comparative Examples is used to illustrate the evaluation of the catalytic activity and the ageing resistace of catalyst
Method according to embodiment 9-16 is estimated the catalytic activity and the ageing resistace of catalyst, and different is the reference catalyst a-j that the catalyst of evaluation prepares for the method that adopts Comparative Examples 1-10.
The result is as shown in table 1.
Table 1
Data from table 1 as can be seen, resulting catalyst is to the initiation temperature T of HC, CO and NOx among the embodiment 1-8
50Scope be respectively 232-245 ℃, 215-220 ℃, 220-232 ℃, than resulting catalyst HC, CO, NOx initiation temperature T among the Comparative Examples 1-10
50Scope be respectively 252-280 ℃, 228-255 ℃, 256-276 ℃ much lower.And through high-temperature roasting aging after, embodiment 1-8 initiation temperature T
50Raising substantially about 30 ℃; And improve among the Comparative Examples 1-10 substantially about 50-80 ℃, therefore the resistant to thermal aging performance of the catalyst that obtained by embodiment 1-8 of explanation is fine.Data from table 1 it can also be seen that the catalytic activity of catalyst provided by the invention is also higher.
Claims (12)
1, a kind of cleaning catalyst for tail gases of automobiles, this catalyst contains carrier with ordered structure and has the inner surface of carrier of ordered structure and/or the coating on the outer surface attached to this, described coating contains matrix and is supported on active component on the described matrix, it is characterized in that, described coating is a multilayer, active component in every layer of coating is palladium or rhodium, the coating that directly contacts with the inner surface and/or the outer surface of the carrier with ordered structure is an innermost layer, active component in the innermost layer coating is a palladium, the coating that contains active component palladium is alternately arranged with the coating that contains the active component rhodium, and total number of plies of coating is an odd number.
2, catalyst according to claim 1, wherein, the gross weight of described coating is the 25-60% of vehicle weight; Volume with described carrier is a benchmark, and each content that contains palladium in the coating of active component palladium is the 0.5-2.2 grams per liter, and the content of rhodium is the 0.02-0.2 grams per liter in the coating of each rhodium-containing; Each contains the coating mesostroma of active component palladium and the weight ratio of active component palladium is 100: 0.5-4, the coating mesostroma of each rhodium-containing and the weight ratio of active component rhodium are 100: 0.01-1.
3, catalyst according to claim 1 and 2, wherein, the number of plies of described coating is three layers, and the innermost layer coating from inside to outside and the weight ratio of carrier are 0.09-0.31: 1, the weight ratio 0.06-0.31 of intermediate layer and carrier: 1, the weight ratio of outermost layer and carrier is 0.06-0.30: 1.
4, catalyst according to claim 1 and 2, wherein, at least also contain auxiliary agent in one deck coating, described auxiliary agent is selected from one or more in the non-noble metal oxide of oxide and VIII family of oxide, rare earth metal of oxide, the VIIB family metal of oxide, the group vib metal of oxide, the VB family metal of oxide, the IVB family metal of oxide, the IIB family metal of oxide, the IB family metal of IIA family metal; The weight ratio of described auxiliary agent and matrix is 0.25-1.5: 1.
5, catalyst according to claim 4, wherein, described auxiliary agent is selected from one or more in the oxide of La, Ce, Pr, Nd, Sm, Eu, Gd, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mg, K, Ca, Sr and Ba.
6, catalyst according to claim 1 and 2, wherein, described carrier with ordered structure is selected from one or more in cordierite honeycomb carrier, mullite honeycomb substrate, cellular alumina carrier and the metal alloy honeycomb substrate; Described matrix is selected from one or more in aluminium oxide, silica, amorphous silicon aluminium, titanium oxide, boron oxide and cerium-zirconium-aluminium composite oxide.
7, the described Preparation of catalysts method of claim 1, this method is included on the inner surface of the carrier with ordered structure and/or the outer surface adheres to the slurry that contains matrix, dry then, roasting, and with the solution impregnation that contains soluble salts of active components, dry then, roasting, described active component is supported on the described matrix, obtain coating, it is characterized in that, described coating is a multilayer, active component in every layer of coating is palladium or rhodium, the coating that directly contacts with the inner surface and/or the outer surface of the carrier with ordered structure is an innermost layer, active component in the innermost layer coating is a palladium, and the coating that contains active component palladium is alternately arranged with the coating that contains the active component rhodium, and total number of plies of coating is an odd number.
8, method according to claim 7, wherein, it is the 25-60% of vehicle weight that the consumption of slurry makes the gross weight of coating; Volume with described carrier is a benchmark, and each content that contains palladium in the coating of active component palladium is the 0.5-2.2 grams per liter, and the content of rhodium is the 0.02-0.2 grams per liter in the coating of each rhodium-containing; Each contains the coating mesostroma of active component palladium and the weight ratio of active component palladium is 1: 0.005-0.08, the coating mesostroma of each rhodium-containing and the weight ratio of active component rhodium are 1: 0.001-0.01.
9, according to claim 7 or 8 described methods, wherein, described coating is three layers, the consumption of slurry make from inside to outside the innermost layer coating and the weight ratio of carrier be 0.09-0.31: 1, the weight ratio 0.06-0.31 of intermediate layer and carrier: 1, the weight ratio of outermost layer and carrier is 0.06-0.30: 1.
10, according to claim 7 or 8 described methods, wherein, the described solid content of slurry that contains matrix is 10-60 weight %, the concentration of the solution of described soluble salts of active components is 2-5 weight %, and described soluble salts of active components is one or more in nitrate, hydrochloride and the acetate; The time of dipping is 2-10 minute.
11, according to claim 7 or 8 described methods, wherein, the presoma that also contains auxiliary agent and/or auxiliary agent in the described slurry that contains matrix, and/or the solution that contains soluble salts of active components also contains the presoma of auxiliary agent and/or auxiliary agent, described auxiliary agent is selected from IIA family metal, IB family metal, IIB family metal, IVB family metal, VB family metal, the group vib metal, VIIB family metal, in the non-noble metal oxide of rare earth metal and VIII family one or more, the presoma of described auxiliary agent is selected from IIA family metal, IB family metal, IIB family metal, IVB family metal, VB family metal, the group vib metal, VIIB family metal, in the non-noble metal soluble-salt of rare earth metal and VIII family one or more, the consumption of the presoma of described auxiliary agent and/or auxiliary agent makes in the catalyst that obtains, and the weight ratio of auxiliary agent and matrix is 0.20-1.8: 1.
12, method according to claim 11, wherein, described metal is selected from one or more among La, Ce, Pr, Nd, Sm, Eu, Gd, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mg, Ca, Sr and the Ba, and described soluble-salt is selected from one or more in nitrate, acetate, hydrochloride, oxalates, malate and the tartrate.
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| CN200810133290A CN101632930A (en) | 2008-07-25 | 2008-07-25 | Catalyst for purifying automobile tail gas and preparation method thereof |
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