Aluminium cerium zirconium compound oxide catalysis material and preparation method thereof
Technical field
The present invention relates to a kind of catalysis material and preparation method thereof, be particularly a kind ofly applicable to purifying vehicle exhaust, organic exhaust gas eliminates and aluminium cerium zirconium compound oxide catalysis material and preparation method thereof of the waste gas purification such as natural gas catalytic combustion or catalytic combustion.
Background technology
Reduce automobile exhaust pollution, environment protection quality, realizing the sustainable development of ecological environment and society, is one of important topic of China environmental protection in the current and following long duration.
For decreasing pollution, must break through from improving gasoline quality, improving engine combustion state and increasing exhaust purification catalytic efficiency three aspect.Up to the present, cleaning catalyst for tail gases of automobiles is used to be that most effective way reduces HC, CO and NO in tail gas by three-way catalytic apparatus exactly
xthe content of three kinds of toxic gases.
Three-way catalyst mainly by catalytic action noble metal active component, containing CeO
2catalyst aid (hydrogen-storing material) and the carrier composition for supporting active component.And suitable purifying vehicle exhaust storage oxygen coating material is to the dispersion of noble metal with stablely to play a key effect, store up the oxygen storage capacity that oxygen coating material can improve catalyst under hot conditions simultaneously, expand its air-fuel ratio operation window, catalyst activity under very harsh operating condition is had clear improvement.
The current commercial rare earth oxygen storage material containing cerium and the γ-Al with the stronger thermal ageing resistant capacity of high-ratio surface sum
2o
3prepare respectively.
Due to CeO
2heat endurance poor, limit its use.Therefore, CeO must be suppressed when at high temperature using
2sintering.When by CeO
2in cerium ion when replacing with other cationic moiety, can fault of construction be produced, significantly improve its high high-temp stability.
Zr0
2add Ce0 to
2in, can Ce0 be formed
2-Zr0
2solid solution and improve Ce0
2body phase behaviour, be beneficial to migration and the diffusion of body phase oxygen atom, make body phase reaction process become active, can Ce0 be improved
2oxygen storage capacity and high-temperature stability.Meanwhile, the rare earths such as Pr, Nd, Y, Nb, La and Ba and alkaline earth element add the high-temperature aging resisting that can strengthen hydrogen-storing material further, improve its oxygen storage capacity.Hydrogen-storing material can the dispersion of effective stabilizing active component, therefore there is large specific area, larger pore volume and suitable pore-size distribution, and there is good high-temperature aging resisting performance, the cerium zirconium based oxygen storage material of excellent low-temperature catalyzed performance becomes the critical material of new three-way catalyst.
γ-Al
2o
3heat endurance, specific area, pore volume, pore-size distribution, surface acidity and NO adsorption capacity affect the catalytic performance of catalyst to a great extent.Improve γ-Al
2o
3high high-temp stability and surface property to improve the activity of catalyst and service life significant.Research shows.The high high-temp stability of aluminium oxide can be improved by adding rare earth, alkaline earth element etc., suppressing aluminium oxide by the transformation of γ α phase in opposite directions.Industrial now widely used be through roasting preparation, there is the aluminium oxide of stronger thermal ageing resistant capacity after surface modification being carried out to boehmite by rare earth element or transition metal.
With rare earth material and the mutual modifications of aluminium oxide such as cerium zirconium based solid solutions, prepare Ce-Zr-Al based composite, make it have the Common advantages of hydrogen-storing material and aluminium oxide concurrently, improving the high temperature ageing resistance of hydrogen-storing material and aluminium oxide, is the key technology of catalyst coatings of new generation.
The Chinese patent patent No. be 200510020615.1 patent of invention disclose a kind of Ce-Zr-Al based oxygen stored material and preparation method thereof, its basic composition is by cerium oxide, zirconia, aluminium oxide and stabilizing agent, and stabilizing agent is selected from least one of lanthana, yittrium oxide and alkaline earth oxide; Its preparation technology is that (1) prepares nitrate mixed solution and alkaline precipitating agent by given material composition component; (2) by prepare two kinds of solution and conductance enter in reaction vessel to precipitate, precipitation terminate after be not less than 2h 90-100 DEG C of ageing; (3) the reaction feed liquid after ageing carries out Separation of Solid and Liquid, and isolated solid phase precipitation thing carries out washing, being then made into slurries with surfactant and water; (4) slurries obtain Ce-Zr-Al based oxygen stored material by evaporation drying, then roasting.
The specific surface agent of the hydrogen-storing material prepared with said method reaches as high as 110m after 1000 DEG C of roasting 5h
2/ more than g, at least can reach 38m
2/ more than g; But the method is raw material with aluminum nitrate, and cost is higher, the hydrogen-storing material aperture of simultaneously preparing is less, the high temperature ageing resistace of hydrogen-storing material is poor.
Chinese patent patent publication No. is that the patent of invention of CN101940921A discloses a kind of bilayer structured oxygen storage material and preparation method thereof, by cerium zirconium sosoloid and Large ratio surface γ-Al
2o
3be composited, its preparation method is: (1) gets lanthanum nitrate hexahydrate, cerous nitrate solution, yttrium nitrate and zirconium nitrate solution, inserts in container to add ammoniacal liquor and carry out precipitation and be precipitated thing; (2) in the sediment of step (1), add the industrial hydrogen peroxide of cerium oxide quality, obtain cerium zirconium precursor compound; (3) by presoma and γ-Al
2o
3mass ratio 1:1 mixes, stirring obtains mixture; (4) by the mixture in step (3) after washing, filter, adding surfactant, then drying, roasting, air-flow crushing, obtain double-deck powder hydrogen-storing material.
Said method is with cerium zirconium precursor body and γ-Al
2o
3mechanical mixture, the caking property which results in the mixing uniformity of aluminium oxide and cerium zirconium compound oxide and aluminium oxide and cerium zirconium compound oxide is poor, affects catalytic performance and the high-temperature thermal stability agent of hydrogen-storing material.
The Chinese patent patent No. be 98108256.4 patent of invention disclose and a kind ofly there is the hydrogen-storing material of high thermal stability and prepare the method for this material, stabilizing agent cerium oxide and at least one being selected from praseodymium oxide, lanthana, yittrium oxide and neodymia is highly dispersed on the specific surface of the high surface area carriers such as aluminium oxide, zirconia, titanium oxide, silica or other oxides, and then obtains through roasting; Its preparation method the precursor of stabilizing agent described in dissolving and cerium oxide be added to a kind of preprepared, constantly stirred selected by carrier mass water dispersion in, then by adding alkali, slowly improve the pH value of dispersion to 8-10, thus stabilizing agent and cerium oxide are deposited on carrier mass.
Said method does not carry out surface treatment to carrier, and the granular size of carrier, pattern etc. all affect the cohesive force of coated uniformity and coat and carrier, affect catalytic activity and the high high-temp stability of hydrogen-storing material.
To sum up, the existing research for Ce-Zr-Al based rare earth oxygen storage material is less, and adhesion between cerium zirconium and aluminium oxide and high temperature ageing resistance also exist larger contradiction, and the high temperature ageing resistance of material is poor.
Therefore, a kind of aluminium cerium zirconium compound oxide catalysis material of special needs and preparation method thereof, to solve above-mentioned existing Problems existing.
Summary of the invention
The object of the present invention is to provide a kind of aluminium cerium zirconium compound oxide catalysis material and preparation method thereof, for the deficiencies in the prior art, have that specific area is large, high temperature ageing resistance is good and store oxygen ability high, be applicable to waste gas purification or the catalytic combustions such as purifying vehicle exhaust, organic exhaust gas elimination and natural gas catalytic combustion.
Technical problem solved by the invention can realize by the following technical solutions:
On the one hand, the invention provides a kind of aluminium cerium zirconium compound oxide catalysis material, it is characterized in that, the composite oxides that it is made up of cerium oxide, zirconia, aluminium oxide and other rare earth oxides except cerium, its percentage by weight is as follows:
Cerium oxide: 15-30%;
Zirconia: 5-20%;
Aluminium oxide: 50-75%;
Other rare earth oxides: 0-5% except cerium.
In one embodiment of the invention, described other rare earth oxides except cerium are selected from the combination of one or more in lanthana, yittrium oxide, praseodymium oxide and neodymia.
On the other hand, the invention provides a kind of preparation method of aluminium cerium zirconium compound oxide catalysis material, it is characterized in that, it comprises the steps:
(1) preparation of active component slurries: according to the composition of material, by water-soluble to corresponding cerous nitrate, other rare earth soluble-salts except cerium and zirconium nitrate, obtains hybrid metal nitrate solution; In hybrid metal nitrate solution, add activated alumina and structure directing agent, shear dispersion, obtain active component slurries A;
(2) precipitate: at a certain temperature, ammoniacal liquor is added in above-mentioned active component slurries A, until precipitation terminal, add Ce
3+be oxidized to Ce
4+required stoichiometric hydrogen peroxide, held for some time, obtains sediment B;
(3) sedimentary surface treatment, is undertaken sediment B dewatering, washing; By sediment B and the water after dehydration with mass ratio 2:1 reslurry, add a certain amount of surface conditioning agent, shear and disperse;
(4) roasting, by surface treated sediment B roasting 4-6h at 550-750 DEG C, obtains described cerium aluminium cerium zirconium compound oxide catalysis material.
In one embodiment of the invention, in step (1), described other rare earth soluble nitrate except cerium are selected from the one or more combination in lanthanum nitrate, yttrium nitrate, praseodymium nitrate, neodymium nitrate, or nitric acid reacts to lanthana, yittrium oxide, praseodymium oxide and neodymia and generates corresponding nitrate solution.
In one embodiment of the invention, in step (1), in described mixed metal salt salpeter solution, the ratio of each nitrate is:
Cerous nitrate 15-30%;
Zirconium nitrate 5-20%;
Other rare earth soluble nitrate 0-5% except cerium.
In one embodiment of the invention, in step (1), in described active component slurries, the addition of activated alumina is the 25%-35% that activated alumina accounts for activated alumina and each metal nitrate summation.
In one embodiment of the invention, in step (1), described activated alumina is selected from gama-alumina that pore volume is 0.3-0.7g/ml or is the gama-alumina that the boehmite of 0.3-0.7g/ml obtains after 3-6h after 450-600 DEG C of roasting by pore volume.
In one embodiment of the invention, in step (1), described structure directing agent is selected from organic ammonium salt, and the addition of described structure directing agent is the 15-30% of the quality summation of each nitrate in mixing.
Further, described structure directing agent is preferably one or both the combination in ammonium citrate and softex kw.
In one embodiment of the invention, in step (2), described Aging Temperature is 60-90 DEG C, and digestion time is 1-4h.
Further, preferably, described Aging Temperature is 80-90 DEG C, and described digestion time is 2-3h.
In one embodiment of the invention, in step (3), described surface conditioning agent is selected from the aliphatic acid or ethers that carbon atom is 6-12, and the addition of described surface conditioning agent is the 30-50% of the weight summation of each nitrate.
Further, described carbon atom is that the aliphatic acid of 6-12 or ethers comprise sad (C
8h
16o
2), capric acid (C
10h
20
2), ethylene glycol monobutyl ether (C
6h
14o
2) and diethylene glycol monobutyl ether (C
8h
18o
3).
Aluminium cerium zirconium compound oxide catalysis material of the present invention and preparation method thereof, compared with prior art, by carrying out surface treatment to aluminium oxide, the interaction on the one hand between oxidation reinforced aluminium and Ce-Zr based composite oxide; Ensure the homogeneity between aluminium oxide and Ce-Zr based composite oxide on the other hand fully; By the modification of structure directing agent and dispersant, further increase aperture and the pore volume of product, there is good high-temperature aging resisting ability, there is oxygen storage capacity high and store the fireballing advantage of oxygen simultaneously, realize object of the present invention.
The detailed description and obtaining that feature of the present invention can consult the graphic and following better embodiment of this case is well understood to.
Accompanying drawing explanation
Fig. 1 is the XRD schematic diagram that embodiments of the invention 1 prepare aluminium cerium zirconium compound oxide catalysis material.
Detailed description of the invention
The technological means realized to make the present invention, creation characteristic, reaching object and effect is easy to understand, below in conjunction with concrete diagram, setting forth the present invention further.
Aluminium cerium zirconium compound oxide catalysis material of the present invention and preparation method thereof, the composite oxides that it is made up of cerium oxide, zirconia, aluminium oxide and other rare earth oxides except cerium, its percentage by weight is as follows:
Cerium oxide: 15-30%;
Zirconia: 5-20%;
Aluminium oxide: 50-75%;
Other rare earth oxides: 0-5% except cerium.
In the present invention, described other rare earth oxides except cerium are selected from the combination of one or more in lanthana, yittrium oxide, praseodymium oxide and neodymia.
The preparation method of aluminium cerium zirconium compound oxide catalysis material of the present invention, it comprises the steps:
(1) preparation of active component slurries: according to the composition of material, by water-soluble to corresponding cerous nitrate, other rare earth soluble-salts except cerium and zirconium nitrate, obtains hybrid metal nitrate solution; In hybrid metal nitrate solution, add activated alumina and structure directing agent, shear dispersion, obtain active component slurries A;
(2) precipitate: at a certain temperature, ammoniacal liquor is added in above-mentioned active component slurries A, until precipitation terminal, add Ce
3+be oxidized to Ce
4+required stoichiometric hydrogen peroxide, held for some time, obtains sediment B;
(3) sedimentary surface treatment, is undertaken sediment B dewatering, washing; By sediment B and the water after dehydration with mass ratio 2:1 reslurry, add a certain amount of surface conditioning agent, shear and disperse;
(4) roasting, by surface treated sediment B roasting 4-6h at 550-750 DEG C, obtains described cerium aluminium cerium zirconium compound oxide catalysis material.
In step (1), described other rare earth soluble nitrate except cerium are selected from the one or more combination in lanthanum nitrate, yttrium nitrate, praseodymium nitrate, neodymium nitrate, or nitric acid reacts to lanthana, yittrium oxide, praseodymium oxide and neodymia and generates corresponding nitrate solution.
In described mixed metal salt salpeter solution, the ratio of each nitrate is:
Cerous nitrate 15-30%;
Zirconium nitrate 5-20%;
Other rare earth soluble nitrate 0-5% except cerium.
In described active component slurries, the addition of activated alumina is the 25%-35% that activated alumina accounts for activated alumina and each metal nitrate summation.
Described activated alumina is selected from gama-alumina that pore volume is 0.3-0.7g/ml or is the gama-alumina that the boehmite of 0.3-0.7g/ml obtains after 3-6h after 450-600 DEG C of roasting by pore volume.
Described structure directing agent is selected from organic ammonium salt, and the addition of described structure directing agent is the 15-30% of the quality summation of each nitrate in mixing; Described structure directing agent is preferably one or both the combination in ammonium citrate and softex kw.
In step (2), described Aging Temperature is 60-90 DEG C, and digestion time is 1-4h; Preferably, described Aging Temperature is 80-90 DEG C, and described digestion time is 2-3h.
In step (3), described surface conditioning agent is selected from the aliphatic acid or ethers that carbon atom is 6-12, and the addition of described surface conditioning agent is the 30-50% of the weight summation of each nitrate; Described carbon atom is that the aliphatic acid of 6-12 or ethers comprise sad (C
8h
16o
2), capric acid (C
10h
20
2), ethylene glycol monobutyl ether (C
6h
14o
2) and diethylene glycol monobutyl ether (C
8h
18o
3).
Embodiment 1
64.9kg cerous nitrate, 29.8kg zirconium nitrate, 13.5kg lanthanum nitrate 500kg pure water are dissolved, adds the γ-Al that 60kg pore volume is 0.31g/ml
2o
3, 16kg ammonium citrate, shear dispersion; After above-mentioned slurries are heated to 60 DEG C, slowly add ammoniacal liquor, the pH controlling terminal is 9, adds the hydrogen peroxide 11.8kg of 30%, insulation 4h.Mix according to mass ratio 2:1 with water after sediment centrifugal dehydration, add diethylene glycol monobutyl ether (C8H18O3) 32.5kg, shear dispersion.By the turbid liquid after dispersion through 550 DEG C of roasting 6h, obtain described aluminium cerium zirconium compound oxide catalysis material.
Consisting of of this material, cerium oxide 24%, zirconia 11%, lanthana 5%, aluminium oxide 60%.The fresh specific area of this material is 140m
2/ g, the specific area obtained after 1000 DEG C of roasting 4h by this material is 101m
2/ g.
Embodiment 2
64.9kg cerous nitrate, 29.8kg zirconium nitrate, 13.5kg lanthanum nitrate 500kg pure water are dissolved, adds the γ-Al that 60kg pore volume is 0.68g/ml
2o
3, 16kg ammonium citrate, shear dispersion; After above-mentioned slurries are heated to 60 DEG C, slowly add ammoniacal liquor, the pH controlling terminal is 9, adds the hydrogen peroxide 11.8kg of 30%, insulation 1h.Mix according to mass ratio 2:1 with water after sediment centrifugal dehydration, add ethylene glycol monobutyl ether (C6H14O2) 54.1kg, shear dispersion.By the turbid liquid after dispersion through 750 DEG C of roasting 4h, obtain described aluminium cerium zirconium compound oxide catalysis material.
Consisting of of this material, cerium oxide 24%, zirconia 11%, lanthana 5%, aluminium oxide 60%.The fresh specific area of this material is 182m
2/ g, the specific area obtained after 1000 DEG C of roasting 4h by this material is 132m
2/ g.
Embodiment 3
64.9kg cerous nitrate, 29.8kg zirconium nitrate, 13.5kg lanthanum nitrate 500kg pure water are dissolved.The boehmite by pore volume being 0.35g/ml must γ-Al after 6h after 450 DEG C of roastings
2o
3, get 60kg γ-Al
2o
3join in above-mentioned solution, 32.46kg softex kw, shear dispersion; After above-mentioned slurries are heated to 60 DEG C, slowly add ammoniacal liquor, the pH controlling terminal is 9, adds the hydrogen peroxide 11.8kg of 30%, insulation 1h.Mix according to mass ratio 2:1 with water after sediment centrifugal dehydration, add ethylene glycol monobutyl ether (C6H14O2) 54.1kg, shear dispersion.By the turbid liquid after dispersion through 600 DEG C of roasting 4h, obtain described aluminium cerium zirconium compound oxide catalysis material.
Consisting of of this material, cerium oxide 24%, zirconia 11%, lanthana 5%, aluminium oxide 60%.The fresh specific area of this material is 193m
2/ g, the specific area obtained after 1000 DEG C of roasting 4h by this material is 145m
2/ g.
Embodiment 4
40.5kg cerous nitrate, 13.5kg zirconium nitrate 500kg pure water are dissolved, adds the γ-Al that 75kg pore volume is 0.68g/ml
2o
3, 25kg ammonium citrate, shear dispersion; After above-mentioned slurries are heated to 90 DEG C, slowly add ammoniacal liquor, the pH controlling terminal is 9, adds the hydrogen peroxide 11.8kg of 30%, insulation 1h.Mix according to mass ratio 2:1 with water after sediment centrifugal dehydration, add sad (C8H16O2) 30kg, shear dispersion.By the turbid liquid after dispersion through 60 DEG C of roasting 4h, obtain described aluminium cerium zirconium compound oxide catalysis material.
Consisting of of this material, cerium oxide 15%, zirconia 5%, aluminium oxide 75%.The fresh specific area of this material is 195m
2/ g, the specific area obtained after 1000 DEG C of roasting 4h by this material is 151m
2/ g.
Embodiment 5
81kg cerous nitrate, 52.6kg zirconium nitrate 500kg pure water are dissolved, adds the γ-Al that 50kg pore volume is 0.51g/ml
2o
3, 25kg ammonium citrate, shear dispersion; After above-mentioned slurries are heated to 90 DEG C, slowly add ammoniacal liquor, the pH controlling terminal is 9, adds the hydrogen peroxide 11.8kg of 30%, insulation 1h.Mix according to mass ratio 2:1 with water after sediment centrifugal dehydration, add capric acid (C10H202) 30kg, shear dispersion.By the turbid liquid after dispersion through 60 DEG C of roasting 4h, obtain described aluminium cerium zirconium compound oxide catalysis material.
Consisting of of this material, cerium oxide 30%, zirconia 20%, aluminium oxide 50%.The fresh specific area of this material is 172m
2/ g, the specific area obtained after 1000 DEG C of roasting 4h by this material is 144m
2/ g.
Embodiment 6
By 54kg cerous nitrate, 26.3kg zirconium nitrate, 2.7kg yttrium nitrate, 1.5kg praseodymium nitrate, 4.5kg neodymium nitrate 500kg pure water dissolves.Be 0.4g/ml 60kg γ-Al by 67kg pore volume
2o
3join in above-mentioned solution, 32.46kg softex kw, shear dispersion; After above-mentioned slurries are heated to 80 DEG C, slowly add ammoniacal liquor, the pH controlling terminal is 9, adds the hydrogen peroxide 9.5kg of 30%, insulation 2h.Mix according to mass ratio 2:1 with water after sediment centrifugal dehydration, add ethylene glycol monobutyl ether (C6H14O2) 54.1kg, shear dispersion.By the turbid liquid after dispersion through 600 DEG C of roasting 4h, obtain described aluminium cerium zirconium compound oxide catalysis material.
Consisting of of this material, cerium oxide 20%, zirconia 10%, yittrium oxide 1%, praseodymium oxide 0.5%, neodymia 1.5%, aluminium oxide 67%.The fresh specific area of this material is 193m
2/ g, the specific area obtained after 1000 DEG C of roasting 4h by this material is 145m
2/ g.
More than show and describe general principle of the present invention and principal character and advantage of the present invention.The technical staff of the industry should understand; the present invention is not restricted to the described embodiments; what describe in above-described embodiment and description just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications; these changes and improvements all fall in the claimed scope of the invention, and application claims protection domain is defined by appending claims and equivalent thereof.