HK1238195A1 - Ceria zirconia alumina composition with enhanced thermal stability - Google Patents

Description

Cerium oxide, zirconium oxide, and aluminum oxide compositions having enhanced thermal stability

This application is a divisional application with application number 201280032493.6. The application date of the parent case is 6/12/2012; the invention relates to a ceria-zirconia-alumina composition with enhanced thermal stability.

Technical Field

The present invention relates to compositions based on cerium oxide (oxide of cerium), zirconium oxide (oxide of zirconium) and aluminium oxide (oxide of aluminium) with enhanced thermal stability.

Background

These compositions may be used as coatings in exhaust after-treatment applications for combustion engines (e.g., fuel engines and diesel engines), for example as components of catalysts (primarily three-way catalysts, TWCs), but also in other parts associated with exhaust gas streams, such as NOx traps, Diesel Oxidation Catalysts (DOCs), and Diesel Particulate Filters (DPFs).

Cerium oxide-zirconium oxide based mixed oxides and aluminum oxides are widely used in automotive applications for catalyst preparation. For example, in WO 2008/113457, a method is described in which a mixed oxide of ceria/zirconia and alumina (lanthanum-doped alumina) is introduced separately to produce a coating and is therefore well-established.

However, other types of composite materials are also attracting attention, consisting of: al (Al)₂O₃The balance being usually CeO₂、ZrO₂And possibly some stabilizers, such as rare earth metal oxides.

For example, the preparation and thermal stability of several Al-Ce-Zr-Y-La oxide compositions are reported in EP 1172139. Discloses a catalyst composed of Al₂O₃/CeO₂/ZrO₂/Y₂O₃/La₂O₃A plurality of compositions of which said oxides are present in said compositions in different ratios. The preparation of materials via co-precipitation starting from the corresponding metal salt solutions, including alumina in the form of Al-nitrate, is described. As an intermediate product after the co-precipitation process is carried out, a suspension of Al-Ce-Zr-Y-La hydroxide is produced, which after calcination is converted into the corresponding oxide (see page 8, lines 1-6). The surface area of the oxides of these compositions is described as being dependent on the Al present in the composition₂O₃The amount of (c). In examples 10 to 22, wherein Al₂O₃In an amount of 21-25% by weight (calculated from the molar ratios disclosed in Table 2), said compound having a specific surface area of less than 15m after being subjected to a heat treatment at 1100 ℃ for 20 hours²In terms of/g (see Table 2, page 14). In Al₂O₃With increasing content, higher surface area values were shown after 1100 ℃/20 hours heat treatment, as disclosed in examples 24, 27 and 31. In more detail, in example 24, it corresponds to having 57% by weight of Al₂O₃Composition of contents, discloses a surface area of 27m after calcination at 1100 ℃/20 hours²In terms of/g, and in terms of corresponding to 63% Al₂O₃Examples of the contents27 and 31, respectively, show 31m after calcination at 1100 deg.C/20 hr²G and 30m²Surface area in g.

In JP 2005246177(A), in "comparative example 4", the preparation of Al via a coprecipitation route is described₂O₃/CeO₂/ZrO₂Composite oxide (molar ratio Al)₂O₃/CeO₂/ZrO₂=1/0.9/1.1, and =26 parts of Al in wt.%₂O₃39.5 parts of CeO₂And 34.5 parts of ZrO₂). In the course of studying the present invention, materials were prepared and their BET measured according to the method disclosed in JP 2005246177 (A). Calcination at 1100 ℃/2 hours gave 6.8m²BET of/g, obtained after calcination at 1100 ℃/20 h to give 4.8m²BET in,/g. From the experiments it is evident that the surface area is significantly reduced after 1100 ℃/2 hours calcination of the material. The reduction in surface area was even more pronounced when heat treated at 1100 deg.c/20 hours.

In CN101690890, a method for preparing a composition comprising Al oxide, Ce oxide, Zr oxide and rare earth oxide is disclosed. The method comprises the following steps: preparing a solution of a mixture of metal salts of cerium, zirconium, aluminum and rare earths and adding a surfactant selected from polyethylene glycol, polyvinyl alcohol, polyacrylamide, cetylammonium bromide or cetylammonium chloride. Shows the result obtained after calcination of the material at 1050 ℃/5 hours>35m²Per g surface area. The material prepared according to the method disclosed in CN101690890 has 20% Al₂O₃、50%CeO₂、27.5%ZrO₂And 2.5% La₂O₃The materials were tested during the study of the present invention using cetylammonium bromide as the surfactant and found to yield 24.9m after 1050 ℃/5 hour calcination²Surface area in g. However, when the material was calcined at 1100 ℃/20 hours, the surface area dropped significantly to 9.9m²The value of/g. Since the BET is already as low as 24.9m after calcination at 1050 ℃/h²G, so it can be reasonably concluded that the surface area will be similarly low after 1100 ℃/2 hours of calcination. Higher calcination temperatureThe degree leads to an even further reduction, which can be compensated by a shorter calcination time. Furthermore, the material prepared according to the method disclosed in CN101690890 has 40% Al₂O₃、45%CeO₂、12.5%ZrO₂And 2.5% La₂O₃Using cetyl ammonium bromide as surfactant, the material showed 48m after calcination at 1050 ℃/5 hours²Surface area in g. However, the surface area showed a significant drop to 26.9m when the material was calcined at 1100 ℃/20 hours²The value of/g. Furthermore, the material prepared according to the method disclosed in CN101690890 has 40% Al₂O₃、45%CeO₂、12.5%ZrO₂And 2.5% La₂O₃Using polyethylene glycol as a surfactant, the material showed 42.5m after calcination at 1050 deg.C/5 hours²Surface area in g. However, after 1100 ℃/2 hours calcination, the surface area showed a drop to 36.8m²A value of/g and decreases to 34.3m when the material is calcined at 1100 ℃/20 hours²The value of/g. Furthermore, the material prepared according to the method disclosed in CN101690890 has 40% Al₂O₃、45%CeO₂、12.5%ZrO₂And 2.5% La₂O₃Using polyacrylamide as the surfactant, the material showed 31.2m after calcination at 1050 deg.C/5 hours²Surface area in g. However, after 1100 ℃/2 hours calcination, the surface area showed a drop to 28.4m²A value of/g and drops to 24.5m when the material is calcined at 1100 ℃/20 hours²The value of/g.

In EP 1900416, Al-Ce-Zr-Y-La-oxides obtained via co-precipitation are disclosed [ e.g. paragraph 0045 ]. However, in the course of the study of the present invention, it was found that Al-Ce-Zr-Y-La-composite oxides prepared according to the description given in EP 1900416 showed 30.9m after heat treatment at 1100 ℃/2 hours²Surface area per g, and shows 21.2m after heat treatment at 1100 ℃/20 hours²Surface area in g.

An improved process for forming hydroxides or oxides of the composition is reported in WO2006/070201The composition oxide comprises (oxide-based) alumina (Al)₂O₃) And zirconium oxide (ZrO)₂) And optionally comprises a material selected from CeO₂、La₂O₃、Nd₂O₃、Pr₆O11、Sm₂O₃、Y₂O₃And optionally at least one member of the other rare earth metal oxides. The composition is described as being prepared by coprecipitation starting from a metal salt solution using caustic as a precipitant. The strict pH range is to be kept small: according to WO2006/070201, the pH must not deviate more than ± 1 during precipitation. Furthermore, the process requires a high-pressure heating step of the separated precipitate at 120 ℃ and then a final calcination of the material, establishing the drawbacks of the preparation process. In example 6 of WO2006/070201 it is reported that the Al/Ce/Zr composition oxide consists of 51% Al₂O₃、14.2%CeO₂And 34.8% ZrO₂Composition which shows 43m after a heat treatment at 850 ℃/4 hours and at 1100 ℃/2 hours²Surface area in g. After more severe ageing (heat treatment at 850 ℃/4 hours and 1200 ℃/2 hours) the composition showed only 16m²Surface area in g. In the course of the study of the present invention, in order to investigate the nature of thermal stability after aging for a longer period of time, the compounds were synthesized according to the method of WO 2006/070201. The surface area value was found to be 41.2m after 1100 ℃/2 h heat treatment²G, BET becomes quite low 19m after 36 hours at 1150 DEG C²/g。

In US 7,939,041, the surface area of different Al-Ce-Zr composite oxides synthesized via a co-precipitation route and additional treatment of the precipitate in an autoclave after calcination at 1100 ℃/2 hours is reported. The highest surface area after 1100 ℃/2 hours of calcination is reported to be 48m²In terms of/g, 46.2% Al₂O₃、26.3%CeO₂、3.3%Pr₆O₁₁And 24.2% ZrO₂A composite oxide of the above composition.

Different preparation methods for Ce-Zr-Al composite oxide spheres without using a co-precipitation step are described in EP 718239a1, example 7. Starting with AlThe material is not a water-soluble Al salt but a hydrated alumina (see also DE 69517440T2), and the process is therefore not a co-precipitation process. Al in the composite oxide₂O₃Content of only 7%, CeO₂Is 29.9% and ZrO₂The content was 63%. Are not given in>Any value of the surface area of the ball after heat treatment at 800 ℃. However, since the composition is based mainly on ZrO₂/CeO₂And the surface area is relatively low (70 m) already after calcination at 800 DEG C²G) it can be reasonably concluded (for example under consideration of the prior art, for example EP 2223905, in which Zr/Ce oxide based materials are described) that such compositions will show a much lower level than 30m after 1100 ℃/20 hours heat treatment²Surface area in g.

It is known from the prior art, for example from EP 2223905, to enhance the surface stability of cerium oxide/zirconium oxide mixed oxides by treating the precipitated metal with a surfactant. This is outlined in several examples, where a precipitate of the metal is treated, for example by lauric acid, and then by converting the treated precipitate to a mixed oxide. The surface area of the cerium oxide/zirconium oxide mixed oxide after a heat treatment of 1100 ℃/4 hours is shown to be only about 22m at the most²The value of/g.

In comparative example C10 of the present application, it is shown that a cerium oxide/zirconium oxide mixed oxide consisting of exactly the same element ratios (based on rare earths) as used in example 1 according to the invention shows 18m after a heat treatment at 1100 ℃/4 hours²Surface area per gram, when surfactant treatment is applied in the process. The improvement in surface stability of the mixed ceria-zirconia oxide after heat treatment of the compound at 1100 ℃/4 hours, even after surface treatment, is relatively low compared to other mixed ceria/zirconia mixed oxides known in the art. For example, in WO 2007/093593, it is disclosed that cerium oxide/zirconium oxide mixed oxides exhibit a maximum of 32m after a heat treatment at 1100 ℃/10 hours²Surface area in g. Furthermore, in comparative examples C11 and C12 of the present application, the reaction mixture is shown consisting of aluminum nitrate nonahydrate (same starting material as used in example 1 according to the invention)The prepared alumina, after being subjected to precipitation and conversion to the corresponding oxide, even after treatment with a surfactant, shows a very low surface area. Thus, the alumina prepared by precipitation and conversion to the oxide showed only 1m after 1100 ℃/4 hours of heat treatment²Surface area in g. Surfactant treatment of the precipitate, as shown in comparative example C12, showed only 6.1m after 1100 deg.C/4 hours of heat treatment of the precipitate²Surface area in g. Thus, a mixture of 50% ceria/zirconia and 50% alumina (both prepared by separate precipitation processes and additional applications of surfactants known in the art) would result with only one<15m²A surface area per gram of the composite oxide.

From the data disclosed in EP 2223905 and from the experiments that have been carried out as described above, it can be reasonably concluded that compositions based on Ce/Zr and alumina (manufactured by precipitation and use of surfactants, respectively) made from metal nitrate solutions will result in products with only low surface stability. The examples show that it is not possible to prepare thermally stable compositions based on ceria zirconia-alumina, even with the aid of surfactants.

From the examples outlined in EP 1172139, for example from example 24 (Ce/Zr compound containing 57% alumina) and example 26 (ceria/zirconia compound containing 46% alumina), it can be concluded that the co-precipitation method may contribute slightly to the surface stability of the resulting composite oxide. However, the compounds exhibiting an alumina content of at most 60% exhibit a virtually only moderate surface stability, not exceeding 32m after calcination of the compound at 1100 ℃/20 hours²The value of/g. This conclusion is also confirmed by the experiments described in comparative example C1 of the present application. In the case of a coprecipitation process carried out according to the method disclosed in EP 1172139, having a compound related to the same composition as disclosed in example 1 of the invention, in fact results in a material which, after 1100 ℃ for 20 hours of ageing, shows only 30.7m²Surface area in g. After a short calcination time, for example 1100 ℃ for 2 hours, 47m are measured²Surface area in g, which is extended to 2 in the calcination timeAt 0 hours there is a significant drop.

After heat treatment, the surface area in the alumina-ceria-zirconia mixed oxide (prepared via co-precipitation) is moderately increased compared to the separate precipitates of ceria/zirconia and alumina, which can be attributed to the stability of the porous system caused by the alumina in the ceria zirconia system. This stabilization of ceria-zirconia is described, for example, by Tadashi Suzuki et al, R & D driver of Toyota CRDL, Vol.37, No. 4, page 28 and thereafter.

Despite the fact that oxides of alumina and ceria/zirconia and composite oxides of Al/Ce/Zr have been used in automotive applications worldwide, there is still a need to improve the production routes and performance of these materials, especially with respect to their thermal stability, to avoid a rather high reduction of the surface area when exposing these materials to higher temperatures and to increase the lifetime of these catalysts.

Disclosure of Invention

In particular, it is an object of the present invention to solve the disadvantages associated with the limited thermal stability of Al/Ce/Zr compositions and to provide compositions with enhanced surface stability, in particular after long term aging.

It has now surprisingly been found that when a composite oxide is prepared according to the process according to the invention, a synergistic effect on thermal stability can be achieved, the resulting ceria zirconia alumina composite oxide having a significantly higher thermal stability after a heat treatment at 1100 ℃/2 hours and/or at 1100 ℃/20 hours.

In one aspect of the present invention, there is provided a process for preparing a composition comprising Al oxide, Ce oxide and Zr oxide, the process comprising the steps of:

(a) preparing an aqueous solution of a mixture of metal salts of cerium, zirconium and aluminum, optionally containing one or more salts of rare earth metals other than cerium,

(b) at a temperature of 0 ℃ to 95 ℃, preferably room temperature, optionally in H₂O₂Adding a base to the solution obtained in step (a) in the presence of (b) and precipitating the obtained mixed metal salt in the form of a hydroxide or oxyhydroxide,

(c) optionally separating the precipitate obtained in step (b),

(d) treating the aqueous suspension obtained in step (b), or the separated precipitate obtained in step (c), with a surfactant, and

(e) separating the precipitate obtained in step (d) and treating the precipitate at a temperature of 450 ℃ to 1200 ℃, preferably 600 ℃ to 1200 ℃, characterized in that

The aluminium content, calculated as the alumina obtained, is from 35 to 80% by weight, preferably from 35 to 75% by weight, more preferably from 35 to 65% by weight, for example from 45 to 65% by weight, more preferably from 40 to 60% by weight, most preferably from 45 to 55% by weight of the composition, and

the surface area (BET) of the composition obtained after calcination at 1100 ℃ for 2 hours was measured according to DIN (Deutsche Industrie Standard) 66131 as 55m²/g-80m²(ii)/g; and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²Per g), e.g. 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g。

In a preferred embodiment of the invention, the surfactant is selected such that the resulting composition has a surface area (BET) of 55m²/g-80m²Measured after calcination at 1100 ℃ for 2 hours in accordance with DIN (Deutsche Industrie Standard) 66131; and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²Per g), e.g. 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g。

In another preferred embodiment of the invention, the cerium content obtained is 5-70% by weight, preferably 5-50% by weight, more preferably 5-30% by weight, most preferably 5-15% by weight of the composition, calculated as cerium oxide.

In another preferred embodiment of the invention, the zirconium content obtained is 5 to 70% by weight, preferably 10 to 60% by weight, more preferably 20 to 50% by weight, most preferably 30 to 40% by weight of the composition, calculated as zirconium oxide.

In another preferred embodiment the aluminium content is from 35 to 80% by weight, preferably from 35 to 75% by weight, more preferably from 35 to 65% by weight, such as from 45 to 65% by weight, for example from 40 to 60% by weight, most preferably from 45 to 55% by weight of the composition, calculated as alumina obtained.

In a further preferred embodiment of the invention, the cerium content obtained, calculated as cerium oxide, is from 5 to 70% by weight, preferably from 5 to 50% by weight, more preferably from 5 to 30% by weight, of the composition obtained. Most preferably 5-15% by weight; and/or the zirconium content obtained is 5-70% by weight, preferably 10-60% by weight, more preferably 20-50% by weight, most preferably 30-40% by weight of the composition obtained, calculated as zirconium oxide; and/or an aluminium content, calculated as alumina obtained, of from 35 to 80% by weight of the composition, preferably from 35 to 75% by weight, more preferably from 35 to 65% by weight, more preferably from 40 to 60% by weight, most preferably from 45 to 55% by weight; and in another preferred aspect, the cerium content, zirconium content, and aluminum content are within a combination of any of the recited content ranges.

In a further preferred embodiment of the invention, the aluminum content, calculated as the aluminum oxide obtained, is from 35 to 75% by weight of the composition and the surface area (BET) of the composition obtained, measured after calcination at 1100 ℃ for 2 hours in accordance with DIN (Deutsche Industrie Standard) 66131, is from 55 to 80m²(ii)/g; and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²(iv)/g); for example 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g；

For example, the aluminum content inThe alumina obtained is calculated as 35-65% by weight of the composition and the surface area (BET) of the composition obtained, measured according to DIN (Deutsche Industrie Standard) 66131 after calcination at 1100 ℃ for 2 hours, is 55-80m²(ii)/g; and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²(iv)/g); for example 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g；

For example, the aluminum content is 45 to 65% by weight of the composition, calculated as the aluminum oxide obtained, and the surface area (BET) of the composition obtained, measured in accordance with DIN (Deutsche Industrie Standard) 66131 after calcination at 1100 ℃ for 2 hours, is 55 to 80m²(ii)/g; and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²(iv)/g); for example 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g；

For example, the aluminum content is 40 to 60% by weight of the composition, calculated as the aluminum oxide obtained, and the surface area (BET) of the composition obtained, measured in accordance with DIN (Deutsche Industrie Standard) 66131 after calcination at 1100 ℃ for 2 hours, is 55 to 80m²(ii)/g; and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²(iv)/g); for example 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g。

Cerium oxide as used herein includes Ce₂O₃And CeO₂CeO is preferred₂。

Alumina as used herein includes Al₂O₃。

Zirconia as used herein includes ZrO₂。

The aqueous solution of the mixture of metal salts in step (a) is prepared by dissolving the water-soluble metal salt or by treatment with an acid (e.g. HNO)₃HCl treatment) to dissolve a metal salt insoluble in water. The water-soluble metal salt comprises a nitrate and/or halide, such as a chloride, and the water-insoluble metal salt comprises a carbonate and/or hydroxide.

In the compositions obtained according to the process of the invention, the Ce oxide, Zr oxide may optionally be present in the form of a solid-solid solution.

The method provided by the invention is herein also labeled "(method according to) the invention" and the composition provided according to the invention is herein also labeled "(composition according to) the invention".

An advantageous embodiment of the process according to the invention is characterized in that the Ce/Zr/Al metal salt solution used according to step (a) comprises at least one rare earth metal element, preferably selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, e.g. La, Nd.

According to the present invention, it has been surprisingly found that the use of a surfactant in the process of the present invention can significantly improve the stability of the surface area of the obtained composition, provided that all other measurement criteria are met.

Suitable surfactants for use in the method of the invention include compounds that lower the interfacial tension of liquids and solids, including for example organic compounds, for example such compounds are amphoteric and contain both hydrophobic and hydrophilic groups. Preferred surfactants include nonionic surfactants, e.g. comprising ethylene oxide/propylene oxide units, e.g. Triton^®，Tergitol^®Examples include ethylphenol ethoxylate and ethylene oxide/propylene oxide copolymer, or lauric acid.

In a preferred embodiment of the invention, lauric acid or Triton is used as the surfactant.

The amount of surfactant applied may have an effect on the stability of the surface area.

Preferred amounts of surfactant to be used include from 20% by weight to 80% by weight, more preferably from 25% by weight to 75% by weight, for example from 30% by weight to 70% by weight of the final composition after calcination.

In a further aspect of the invention there is provided a composition obtainable (e.g. obtained) according to the process of the invention, e.g. a catalyst composition, e.g. a composition comprising Al oxide, Ce oxide and Zr oxide, characterised in that the aluminium content, calculated as alumina, is 35-80%, e.g. 35-65%, e.g. 45-65%, e.g. 40-60%, e.g. 45-55%, by weight and that the surface area (BET) of the composition is 55-80m measured according to DIN (Deutsche Industrie standard) 66131 at 1100 ℃ over a period of 2 hours²/g, and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like at least 38 m)²Per g), e.g. 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g。

The increase in surface area of the composition obtainable or obtained according to the invention after heat treatment of the material at 1100 ℃/20 hours is at least 10%, preferably 20%, more preferably 30%, most preferably 40-50% compared to the material prepared without surfactant treatment.

The significant increase in surface area of the compositions obtained according to the process of the invention compared to the material prepared without surfactant treatment is well demonstrated in examples 1, 2, 3 and 4. The compounds referred to in examples 1-4 showed 46%, 52%, 36% and 79% surface area increase compared to the compounds referred to in comparative examples C1-C4, which were prepared without surfactant treatment.

The BET of the composition of the invention (e.g.obtained or obtainable according to the invention), measured after calcination at 1100 ℃ for 2 hours according to DIN (Deutsche Industrie Standard) 66131, is about, for example, 55m²/g-80m²In g, e.g. 55 to 75m²Per g, e.g. 55 to 70m²In g, e.g. 60 to 70m²/g, and/or at least 35m after calcination at 1100 ℃ for 20 hours²G (like to38m less²(iv)/g); for example 35m²G (like 38 m)²Per g) to 80m²G, e.g. 35m²G (like 38 m)²Per g) to 65m²/g。

In yet another aspect of the present invention, there is provided a process for preparing a composition comprising Al oxide, Ce oxide and Zr oxide, the process comprising the steps of:

(a) preparing an aqueous solution of a mixture of metal salts of cerium, zirconium and aluminum, optionally containing one or more salts of rare earth metals other than cerium,

(b) optionally in H at a temperature of 0 ℃ to 95 DEG C₂O₂Adding a base to the solution obtained in step (a) in the presence of (b) and precipitating the obtained mixed metal salt in the form of a hydroxide or oxyhydroxide,

for example by dissolving water-soluble salts, e.g. nitrates, halides, e.g. chlorides, or by acid treatment (e.g. by treatment with HNO)₃HCl treatment) dissolved metal salts that are insoluble in water, such as carbonates, hydroxides,

(c) optionally separating the precipitate obtained in step (b),

(d) treating the aqueous suspension obtained in step (b), or the separated precipitate obtained in step (c), with a surfactant, and

(e) separating the precipitate obtained in step (d) and treating the precipitate at a temperature of 450 ℃ to 1200 ℃,

characterized in that the surface area (BET) of the composition obtained after calcination at 1100 ℃ for 2 hours is from 55 to 80m, measured according to DIN (Deutsche Industrie Standard) 66131²In g, e.g. 55 to 75m²Per g, e.g. 55 to 70m²In g, e.g. 60 to 70m²(ii) in terms of/g. Wherein the composition has an alumina content of 40-60% by weight.

The process of the present invention can be used to prepare compositions having significantly advantageous and unexpected properties as described herein, for example, useful in catalyst compositions, for example, for exhaust gas aftertreatment of combustion engines.

The percentages (%) of the metal salts described herein, including the examples and comparative examples, are by weight.

In the following examples, all temperatures are in degrees Celsius (. degree. C.) and are uncorrected.

Surface area (BET) analysis was carried out using Quantachrome NOVA 4000 according to DIN (Deutsche Industrie standard) 66131.

Detailed Description

Preparation of the composition according to the invention

Example 1

CeO₂(10%)ZrO₂(36.5%)La₂O₃(1%)Nd₂O₃(2.5%)Al₂O₃(50%) Synthesis

92.8g of aqueous zirconium nitrate solution (ZrO)₂Content =29.5%), 26.32g of aqueous cerium nitrate solution (CeO)₂Content =28.5%), 1.99g lanthanum nitrate in crystalline form (La)₂O₃Content =37.7%), 4.91g of neodymium nitrate in crystalline form (Nd)₂O₃Content =38.2%) and 275.74g of aluminum nitrate nonahydrate (Al)₂O₃Content =13.6%), treated with 600ml of deionized water, the mixture obtained is stirred for a few minutes and a clear solution is obtained. To the resulting mixture was added 74.6ml of 35% H with water cooled to 10 deg.C₂O₂And the obtained mixture was stirred for about 45 minutes. To the mixture obtained, an aqueous 24% ammonia solution cooled to 10 ℃ was added until pH =9.5 was adjusted. The resulting mixture was stirred for 15 minutes and a precipitate formed. Filtering the obtained mixture and de-ionizing the obtained precipitateWashed with water and impregnated with 22.7g of Triton X-100. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours to give 75g of CeO₂(10%)ZrO₂(36.5%)La₂O₃(1%)Nd₂O₃(2.5%)Al₂O₃(50%) composite oxide.

BET (fresh material) 162m after 850 ℃/4 h²/g

BET of 127.5m after 950 ℃/5 hours²/g

BET of 116.5m after 1000 ℃/4 hours²/g

BET of 66.2m after 1100 ℃/2 h²/g

BET of 45.2m after 1100 ℃/20 h²/g。

Example 2

CeO₂(25%)ZrO₂(20%)La₂O₃(2.5%)Nd₂O₃(2.5%)Al₂O₃(50%) Synthesis

44.58g of an aqueous zirconium oxynitrate solution (ZrO)₂Content =22.43%), 42.44g of aqueous cerium nitrate solution (CeO)₂Content =29.45%), 3.32g lanthanum nitrate in crystalline form (La)₂O₃Content =37.7%), 3.3g of neodymium nitrate in crystalline form (Nd)₂O₃Content =37.93%) and 183.82g of aluminum nitrate nonahydrate (Al)₂O₃Content =13.6%), treated with 600ml of deionized water, the mixture obtained is stirred for a few minutes and a clear solution is obtained. To the resulting mixture was added 42.78ml of aqueous 35% H₂O₂(cooled to 10 ℃) and the mixture obtained is stirred for about 45 minutes. To the resulting mixture was added an aqueous 24% ammonia solution (cooled to 10 ℃) until adjusted to pH = 9.5. The obtained mixture was stirred for 10 minutes, 20.71g of lauric acid was added and the obtained mixture was further stirred vigorously at room temperature for 1 hour. A precipitate formed. Filtering the obtained mixture and using the obtained precipitateAnd (5) washing with deionized water. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

50g of CeO were obtained₂(25%)ZrO₂(20%)La₂O₃(2.5%)Nd₂O₃(2.5%)Al₂O₃(50%) composite oxide.

BET of 55m after 1100 ℃/2 hours²/g。

BET of 49.5 m after 1100 ℃/20 hours²/g。

Example 3

Al₂O₃(50%) CeO₂(12.5%) ZrO₂(35%) Nd₂O₃(2.5%) Synthesis

Preparing a mixed metal nitrate solution by: 84.66g of a cerium nitrate solution (CeO)₂29.53%), 301.2g of zirconyl nitrate solution (ZrO)₂23.24%), 13.18g of neodymium nitrate hexahydrate (Nd)₂O₃37.93%) and 733.68g of aluminum nitrate nonahydrate (Al)₂O₃: 13.63%) was dissolved in 2.0L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. 189.01ml of 35% H₂O₂(cooled at 10 ℃) was added to the obtained mixture and the obtained mixture was stirred at room temperature for 45 minutes. An aqueous 18% ammonia solution (cooled to 10 ℃) was added to the mixture obtained in a short time and the pH was adjusted to 9.5 and a precipitate formed. The obtained mixture was stirred for 15 minutes, 86.21g of lauric acid was added and the obtained mixture was stirred vigorously at room temperature for 1 hour. The obtained mixture was filtered and the obtained precipitate was washed with deionized water. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

200g of Al were obtained₂O₃(50%) CeO₂(12.5%) ZrO₂(35%) Nd₂O₃(2.5%) composite oxide.

850 ℃/4 h, BET:129m²/g

1100 ℃/20 h, BET 39.5m²/g。

Example 4

Al₂O₃(50%) CeO₂(23.5%) ZrO₂(23.5%) Nd₂O₃(3%) Synthesis

Preparing a mixed metal nitrate solution by: 46.01g of a cerium nitrate solution (CeO)₂25.54%), 47.73g of zirconyl nitrate solution (ZrO)₂24.62%), 3.95g of neodymium nitrate hexahydrate (Nd)₂O₃37.93%) and 187.41g of aluminum nitrate nonahydrate (Al)₂O₃: 13.34%) was dissolved in 1.0L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. 45.75ml of 35% H₂O₂(cooled at 10 ℃) was added to the obtained mixture and the obtained mixture was stirred at room temperature for 45 minutes. An aqueous 18% ammonia solution (cooled to 10 ℃) was added to the resulting mixture for a short time, and the pH was adjusted to 9.5. A precipitate formed. The obtained mixture was stirred for 15 minutes, 33.43g of lauric acid was added and the obtained mixture was stirred vigorously at room temperature for 1 hour. The obtained mixture was filtered and the obtained precipitate was washed with deionized water. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

50g of Al was obtained₂O₃(50%) CeO₂(23.5%) ZrO₂(23.5%) Nd₂O₃(3%) composite oxide.

850 ℃/4 h, BET 138m²/g

1100 ℃/20 h, BET 39.1m²/g。

Example 5

Al₂O₃(65%) CeO₂(17.25%) ZrO₂(13.5%) La₂O₃(2.125%) Nd₂O₃(2.125%) Synthesis

Preparing a mixed metal nitrate solution by: 29.92g of a cerium nitrate solution (CeO)₂28.83%), 27.42g of zirconyl nitrate solution (ZrO)₂24.62%), 2.8g of lanthanum nitrate hexahydrate (La)₂O₃: 37.93%), 2.86g of neodymium nitrate hexahydrate (Nd)₂O₃37.1%) and 833.33g of aluminum nitrate solution (Al)₂O₃: 3.9%) was dissolved in 1.0L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. 76.89ml of 35% H₂O₂(cooled at 10 ℃) was added to the obtained mixture and the obtained mixture was stirred at room temperature for 45 minutes. An aqueous 18% ammonia solution (cooled to 10 ℃) was added to the obtained mixture over a short period of time, and the pH was adjusted to 9.5. A precipitate formed. The resulting mixture was stirred for 15 minutes. The obtained mixture was filtered and the obtained precipitate was washed with deionized water. The obtained wet cake was impregnated with 23.82g Triton X-100, dried at 120 ℃ and calcined at 850 ℃/4 hours.

50g of Al was obtained₂O₃(65%) CeO₂(17.5%) ZrO₂(13.5%) La₂O₃(2.125%) Nd₂O₃(2.125%) composite oxide.

850 ℃/4 h, BET:157m²/g

1100 ℃/2 h, BET 66m²/g

1100 ℃/20 h, BET:54m²/g。

Example 6

Al₂O₃(50%) CeO₂(40%) ZrO₂(5%) La₂O₃(2.5%) Nd₂O₃(2.5%) Synthesis

Preparing a mixed metal nitrate solution by: 69.37g of a cerium nitrate solution (CeO)₂28.83%), 10.15g of zirconyl nitrate solution (ZrO)₂24.62%), 3.37g of lanthanum nitrate hexahydrate (La)₂O₃: 37.1%), 3.3g of neodymium nitrate hexahydrate (Nd)₂O₃: 37.9%) and 641.03g of aluminum nitrate solution (Al)₂O₃: 3.9%) was dissolved in 2.0L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. 40.21ml of 35% H₂O₂(cooled at 10 ℃) was added to the obtained mixture and the obtained mixture was stirred at room temperature for 45 minutes. An aqueous 18% ammonia solution (cooled to 10 ℃) was added to the resulting mixture for a short time, and the pH was adjusted to 9.5. A precipitate formed. The obtained mixture was stirred for 15 minutes, 19.85g of lauric acid was added and the obtained mixture was stirred vigorously at room temperature for 1 hour. The obtained mixture was filtered and the obtained precipitate was washed with deionized water. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

50g of Al was obtained₂O₃(50%) CeO₂(40%) ZrO₂(5%) La₂O₃(2.5%) Nd₂O₃(2.5%) composite oxide.

850 ℃/4 h, BET 97.3m²/g

1100 ℃/2 h, BET 43.8m²/g。

Example 7

Al₂O₃(50%) CeO₂(40%) ZrO₂(5%) La₂O₃(2.5%) Nd₂O₃(2.5%) Synthesis

Preparing a mixed metal nitrate solution by: 69.37g of a cerium nitrate solution (CeO)₂28.83%), 10.15g of zirconyl nitrate solution (ZrO)₂24.62%), 3.37g of lanthanum nitrate hexahydrate (La)₂O₃: 37.1%), 3.3g of neodymium nitrate hexahydrate (Nd)₂O₃: 37.9%) and 641.03g of aluminum nitrate solution (Al)₂O₃: 3.9%) was dissolved in 2.0L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. 40.21ml of 35% H₂O₂(cooled at 10 ℃) was added to the obtained mixture and the obtained mixture was stirred at room temperature for 45 minutes. An aqueous 18% ammonia solution (cooled to 10 ℃) was added to the resulting mixture for a short time, and the pH was adjusted to 9.5. A precipitate formed. The obtained mixture was stirred for 15 minutes, filtered and the obtained precipitate was washed with deionized water. The wet cake obtained was impregnated with 21.72g of Triton X-100. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

50g of Al was obtained₂O₃(50%) CeO₂(40%) ZrO₂(5%) La₂O₃(2.5%) Nd₂O₃(2.5%) composite oxide.

850 ℃/4 h, BET:109m²/g

1100 ℃/2 h, BET 43.4m²/g。

Example 8

Al₂O₃(65%) CeO₂(7%) ZrO₂(25.55%) Nd₂O₃(1.75%) La₂O₃(0.75%) Synthesis

Preparing a mixed metal nitrate solution by: 13.7g of a cerium nitrate solution (CeO)₂25.54%), 51.89g of zirconyl nitrate solution (ZrO)₂: 24.62%), 2.31g of neodymium nitrate hexahydrate (Nd)₂O₃: 37.93%), 0.94g of lanthanum nitrate hexahydrate (La)₂O₃: 37.1%) and 243.63g of aluminum nitrate nonahydrate (Al)₂O₃: 13.34%) was dissolved in 1.0L of deionized water at room temperature. The resulting mixture was stirred for several minutes and a clear solution was obtained. 33.44ml of 35% H₂O₂(cooled at 10 ℃) was added to the obtained mixture and the obtained mixture was stirred at room temperature for 45 minutes. An aqueous 18% ammonia solution (cooled to 10 ℃) was added to the resulting mixture for a short time, and the pH was adjusted to 9.5. The resulting mixture was stirred for 15 minutes, a precipitate was formed, the mixture was filtered and the obtained solid was washed with deionized water. The wet cake obtained was impregnated with 39.42g of Triton X-100 and dried at 120 ℃. The dried product obtained was calcined at 850 ℃/4 hours.

50g of Al was obtained₂O₃(65%) CeO₂(7%) ZrO₂(25.55%) Nd₂O₃(1.75%) La₂O₃(0.75%) composite oxide.

850 ℃/4 h, BET 70m²/g

1100 ℃/2 h, BET 67.6 m²/g

1100 ℃/20 h, BET 52 m²/g。

From examples 1 to 8, it is evident that the BET values of the compositions prepared according to the invention are surprisingly much higher than those of the compositions prepared according to the prior art, as can be seen, for example, from comparative examples C1 to C12 below.

Comparative examples

Comparative example C1

CeO₂(10%) ZrO₂(36.5%) La₂O₃(1%) Nd₂O₃(2.5%) Al₂O₃(50%) Synthesis

Prepared according to the method disclosed in example 1 of EP 1172139

92.8g of aqueous zirconium nitrate solution (ZrO)₂Content =29.5%), 26.32g of aqueous cerium nitrate solution (CeO)₂Content =28.5%), 1.99g lanthanum nitrate in crystalline form (La)₂O₃Content =37.7%), 4.91g of neodymium nitrate in crystalline form (Nd)₂O₃Content =38.2%) and 275.74g of nonawaterAluminium nitrate (Al)₂O₃Content =13.6%), treated with 600ml of deionized water, the mixture obtained is stirred for a few minutes and a clear solution is obtained. To the resulting mixture was added 4.62ml of 35% H with water cooled to 10 deg.C₂O₂And the obtained mixture was stirred for about 20 minutes. To the mixture obtained, an aqueous 24% ammonia solution cooled to 10 ℃ was added until pH =7 was reached. A precipitate formed. The resulting mixture was stirred for 15 minutes. The resulting mixture was filtered and the resulting precipitate was separated and washed with deionized water. The obtained wet cake was dried at 120 ℃ and heat-treated at 300 ℃/5 hours and calcined at 700 ℃/5 hours.

300 deg.C/5 hr and

BET (fresh Material) 148 m after 700 ℃/5 h²/g

BET of 101 m after 950 ℃/5 hours²/g

BET of 92 m after 1000 ℃/4 hours²/g

BET of 47m after 1100 ℃/2 hours²/g

BET of 31m after 1100 ℃/20 hours²/g。

Comparative example C2

CeO₂(25%) ZrO₂(20%) La₂O₃(2.5%) Nd₂O₃(2.5%) Al₂O₃(50%) Synthesis

44.58g of an aqueous zirconium oxynitrate solution (ZrO)₂Content =22.43%), 42.44g of aqueous cerium nitrate solution (CeO)₂Content =29.45%), 3.32g lanthanum nitrate in crystalline form (La)₂O₃Content =37.7%), 3.3g of neodymium nitrate in crystalline form (Nd)₂O₃Content =37.93%) and 183.82g of aluminum nitrate nonahydrate (Al)₂O₃Content =13.6%), treated with 600ml of deionized water, the mixture obtained is stirred for a few minutes and a clear solution is obtained. To the resulting mixture was added 42.78ml of aqueous 35% H₂O₂(Cooling to 10 ℃ C.)) And the resulting mixture was stirred for about 45 minutes. To the resulting mixture was added an aqueous 24% ammonia solution (cooled to 10 ℃) until adjusted to pH = 7.5. A precipitate formed. The resulting mixture was stirred for 15 minutes. The obtained mixture was filtered and the obtained precipitate was washed with deionized water. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

50g of CeO were obtained₂(25%) ZrO₂(20%) La₂O₃(2.5%) Nd₂O₃(2.5%) Al₂O₃(50%) composite oxide.

BET of 39 m after 1100 ℃/2 hours²/g。

BET of 32.5 m after 1100 ℃/20 h²/g。

Comparative example C3

Al₂O₃(50%) CeO₂(12.5%) ZrO₂(35%%) Nd₂O₃(2.5%) Synthesis

Preparing a mixed metal nitrate solution by: 84.66g of a cerium nitrate solution (CeO)₂29.53%), 301.2g of zirconyl nitrate solution (ZrO)₂23.24%), 13.18g of neodymium nitrate hexahydrate (Nd)₂O₃37.93%) and 733.68g of aluminum nitrate nonahydrate (Al)₂O₃: 13.63%) was dissolved in 2.5L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. An aqueous 18% ammonia solution was added to the resulting mixture until the pH was adjusted to 3, and 19.25ml of 35% H was added₂O₂Added to the obtained mixture simultaneously with the ammonia solution. A precipitate formed and the resulting mixture was stirred vigorously. An aqueous 18% ammonia solution was further added to the resulting mixture until the pH was adjusted to 7.25. The resulting mixture was stirred for 15 minutes. The obtained mixture was filtered and the obtained precipitate was washed with deionized water. The obtained wet cake was dried at 120 ℃ and calcined at 850 ℃/4 hours.

200g ofAl₂O₃(50%) CeO₂(12.5%) ZrO₂(35%%) Nd₂O₃(2.5%) composite oxide.

850 ℃/4 h, BET of 115 m²/g

1100 ℃/20 h, BET:29 m²/g。

Comparative example C4

Al₂O₃(50%) CeO₂(23.5%) ZrO₂(23.5%) Nd₂O₃(3%) Synthesis

Preparing a mixed metal nitrate solution by: 159.16g of a cerium nitrate solution (CeO)₂29.53%), 202.2g of zirconyl nitrate solution (ZrO)₂23.24%), 15.82g of neodymium nitrate hexahydrate (Nd)₂O₃37.93%) and 733.68g of aluminum nitrate nonahydrate (Al)₂O₃: 13.63%) was dissolved in 2.0L of deionized water at room temperature. The resulting mixture was stirred for a few minutes and a clear solution was obtained. An aqueous 18% ammonia solution was added to the resulting mixture until a pH of 3 was reached, and 36.2ml of 35% H was added₂O₂Simultaneously with the ammonia solution, to the mixture obtained. The mixture was stirred vigorously and further aqueous 18% ammonia solution was added until the pH was adjusted to 7.25. The resulting mixture was stirred for 15 minutes and a precipitate appeared. The precipitate obtained was separated, washed with deionized water and the wet cake thus obtained was dried at 120 ℃ and calcined at 850 ℃/5 hours. 200g of Al were obtained₂O₃(50%)CeO₂(23.5%)ZrO₂(23.5%)Nd₂O₃(3%) composite oxide material.

850 ℃/5 h, BET:104 m²/g

1100 ℃/20 h, BET of 21.9 m²/g。

Comparative example C5

Al₂O₃(25.98%) CeO₂(39.47%) ZrO₂(34.54%) Synthesis of

359.88g of an aqueous aluminum nitrate nonahydrate solution (Al)₂O₃3.6%) was dissolved in 200g of deionized water. The obtained aqueous solution was mixed with 68.46g of a cerium nitrate solution (CeO)₂28.83%), 70.15g of zirconyl nitrate solution (ZrO)₂24.62%) and 14.62g of 30% H₂O₂And (4) mixing. The obtained mixture was stirred for several minutes to obtain solution 1.

On the other hand, 159.6g of 18% ammonia was mixed with 160g of deionized water to obtain solution 2.

Both the obtained solutions 1 and 2 were mixed under propeller stirring. The mixture obtained is homogenized for about 15 minutes using an ultraturrax. The precipitate formed was filtered and the solid obtained was calcined at 400 ℃/5 hours under air and then treated at 700 ℃/5 hours under air. 50g of composite oxide Al was obtained₂O₃(25.98%) CeO₂(39.47%)ZrO₂(34.54%)。

400 ℃/5 h and 700 ℃/5 h, BET of 119.6 m²/g

1100 ℃/2 hours, BET 6.8m²/g

1100 ℃/20 h, BET of 4.8m²/g。

Comparative example C6

Al₂O₃(20%) CeO₂(50%) ZrO₂(27.5%%) La₂O₃(2.5%) Synthesis

Preparing a mixed metal nitrate solution by: 85.97g of a cerium nitrate solution (CeO)₂29.08%), 58.74g of zirconyl nitrate solution (ZrO)₂23.41%), 3.31g of lanthanum nitrate hexahydrate (La)₂O₃37.81%) and 76.69g of aluminum nitrate nonahydrate (Al)₂O₃: 13.04%) was dissolved in 400ml of deionized water at room temperature. 13.24g of cetyltrimethylammonium bromide was added to the obtained solution and the obtained mixture was stirred for 30 minutes. Mixing the obtained mixture with ammonia/NH₄HCO₃Aqueous solutions of the solutions were co-precipitated and the pH was adjusted to 8.5. A precipitate formed, which was isolated by filtration, washed with deionized water and dried continuously at 120 ℃ for at least 16 hours. The dried precipitate was calcined at 600 ℃ for 3 hours to obtain mixed Al₂O₃(20%)CeO₂(50%) ZrO₂(27.5%%) La₂O₃(2.5%) composite oxide.

1050 ℃/5 h, BET of 24.9m²/g

1100 ℃/20 h, BET of 9.9m²/g。

Comparative example C7

Al₂O₃(40%) CeO₂(45%) ZrO₂(12.5%%) La₂O₃(2.5%) Synthesis

Preparing a mixed metal nitrate solution by: 77.37g of a cerium nitrate solution (CeO)₂29.08%), 26.7g of zirconyl nitrate solution (ZrO)₂23.41%), 0.84g of lanthanum nitrate hexahydrate (La)₂O₃37.81%) and 153.37g of aluminum nitrate nonahydrate (Al)₂O₃: 13.04%) was dissolved in 400ml of deionized water at room temperature. 11.92g of cetyltrimethylammonium bromide was added to the obtained mixture and the obtained mixture was stirred for 30 minutes. Mixing the obtained mixture with ammonia/NH₄HCO₃Aqueous solutions of the solutions were co-precipitated and the pH was adjusted to 8.5. The precipitate formed was isolated by filtration, washed with deionized water and dried continuously at 120 ℃ for at least 16 hours. The dried precipitate was calcined at 600 ℃ for 3 hours to obtain Al₂O₃(40%)CeO₂(45%) ZrO₂(12.5%%) La₂O₃(2.5%) mixed composite oxide.

1050 ℃/5 h, BET of 48m²/g

1100 ℃/20 h, BET of 26.9m²/g。

Comparative example C8

Al₂O₃(80.19%) CeO₂(10.38%) ZrO₂(7.43%) La₂O₃(1.71%) Y₂O₃(0.3%) Synthesis

Preparing a mixed metal nitrate solution by: 18g of a cerium nitrate solution (CeO)₂28.83%), 15.09g of zirconyl nitrate solution (ZrO)₂24.62%), 2.3g of lanthanum nitrate hexahydrate (La)₂O₃37.1%) and 0.5g of yttrium nitrate hexahydrate (Y)₂O₃: 29.32%) and 1179.24g of aqueous aluminum nitrate nonahydrate solution (Al)₂O₃3.4%) was dissolved in 400ml of deionized water at room temperature, and the resulting mixture was stirred at room temperature for 1 hour. The mixed metal nitrate solution obtained was neutralized with an 18% ammonia solution at room temperature while continuously stirring. The resulting mixture was stirred overnight and a precipitate formed. The resulting precipitate was filtered, washed with deionized water and dried at 150 ℃ for at least 16 hours. The dried precipitate was calcined at 600 ℃ for 5 hours and 500 ℃ for 2 hours. 50g of Al was obtained₂O₃(80.19%) CeO₂(10.38%) ZrO₂(7.43%)La₂O₃(1.71%) Y₂O₃(0.3%) the composite oxide was mixed and ground and thus obtained in the form of powder. BET was measured after 1100 ℃/2 hours and 1100 ℃/20 hours.

600 ℃/5 h and 500 ℃/2 h, BET of 170 m²/g

1100 ℃/2 h, BET of 30.9m²/g

1100 ℃/20 h, BET 21.2m²/g。

Comparative example C9

CeO₂(14.2%) ZrO₂(34.8%), Al₂O₃(51%) Synthesis

Preparation according to example 6 of WO2006/070201

112.5g of aluminum nitrate nonahydrate (Al)₂O₃Content =13.6%) was dissolved in 1.5L of deionized waterIn water, 14.77g of an aqueous cerium nitrate solution (CeO) was added thereto₂Content =28.85%) and 43.02g of aqueous zirconyl nitrate solution (ZrO)₂Content = 24.27%). The resulting mixture was stirred for 15 minutes. To the obtained mixture was added 25% aqueous NaOH solution, thus forming a precipitate. The pH was kept close to 10 during precipitation. To the resulting slurry was added 5g of 35% H₂O₂And the pH of the obtained mixture was adjusted to 10. The resulting mixture was stirred for 1 hour and 30% HNO was used₃The pH of the obtained mixture was adjusted to 8. The obtained slurry was kept at 60 ℃ for 1 hour. The mixture obtained was filtered and the solid obtained was washed with deionized water at 60 ℃ until the conductivity of the filtrate did not change any more. The wet cake obtained was separated and resuspended in 850ml of water, the pH of the slurry obtained was adjusted to 10 and the mixture obtained was autoclaved at 120 ℃ for 6 hours. The obtained slurry was cooled down and the pH of the obtained mixture was adjusted to 8 using 30% nitric acid. The resulting mixture was stirred for 30 minutes. The obtained slurry was kept at 60 ℃ for 1 hour and filtered. The solid obtained was washed with deionized water and directly calcined at 850 ℃. BET was measured at different aging temperatures.

BET of 107 m after 850 ℃/4 h²/g

BET of 77 m after 1000 ℃/4 hours²/g

BET of 41.2m after 1100 ℃/2 h²/g

BET of 19m after 1150 ℃/36 hours²/g。

Comparative example C10

ZrO prepared by surfactant treatment₂(73%) CeO₂(20%) La₂O₃(2%) Nd₂O₃(5%) Synthesis

A mixed metal solution corresponding to the composition given above was prepared by: 27.33ml of zirconyl nitrate solution (ZrO) with 121ml of deionized water₂: 22.8%) and 5.045g of cerium (III) nitrate (with 59ml of deionized waterCeO₂39.6%), 0.53g of lanthanum nitrate (La) in 12ml of deionized water₂O₃: 37.4%) and 1.302g of neodymium nitrate (Nd) in 7ml of deionized water₂O₃: 38%) were mixed. The resulting mixture was stirred for several minutes and a clear solution was obtained.

To the solution obtained 23.2ml of H were added₂O₂(30%, Sigma Aldrich, cooled to 5-10 ℃ C.). The obtained mixture was stirred at room temperature for about 45 minutes and a 24% aqueous ammonia solution (cooled to 5-10 ℃ C.) was added to the obtained mixture at a dropping rate of 40 ml/minute at room temperature and brought to pH 9.5. The mixture obtained is kept under stirring for a few minutes. A precipitate formed and the temperature of the mixture was increased to 60 ℃ during precipitation. Impregnation of the precipitate in the reaction mixture was carried out by adding 3.77g of lauric acid to the reaction mixture. The slurry thus obtained is kept under vigorous stirring for at least 4 hours. The obtained mixture was filtered and the obtained solid was thoroughly washed with deionized water. The obtained filter cake was dried in an oven at 100 ℃ overnight (16 hours) and calcined at 500 ℃ for 4 hours. 10 g of ZrO₂(73%) CeO₂(20%) La₂O₃(2%) Nd₂O₃(5%) composite oxide.

BET (fresh) 110 m after 500 ℃/4 h²/g

1100 ℃/4 hr BET (aged): 18m²/g。

Comparative example C11

Synthesis of alumina (Al) from aluminum nitrate nonahydrate₂O₃)

100g of aluminum nitrate nonahydrate was dissolved in 500ml of deionized water and 18% ammonia solution (cooled at 10 ℃) was added to the obtained mixture until the pH was adjusted to 7.5. The obtained mixture was further stirred for 15 minutes, filtered, and the obtained solid was washed with deionized water. The wet cake thus obtained was dried at 120 ℃ overnight and the obtained dried material was calcined at 500 ℃/4 hours. 13.6g of alumina was obtained. BET was measured after calcining the material at 1100 deg.C/4 hr.

BET of 138m after 500 ℃/4 h²/g

BET of 1m after 1100 ℃/4 hours²/g。

Comparative example C12

Synthesis of alumina (Al) from aluminum nitrate nonahydrate using a surfactant₂O₃)

100g of aluminum nitrate nonahydrate was dissolved in 500ml of deionized water and 18% aqueous ammonia solution (cooled at 10 ℃) was added to the resulting mixture until the pH was adjusted to 7.5. The resulting mixture was further stirred for 15 minutes and filtered. The obtained solid was washed with deionized water. The wet cake thus obtained was impregnated with 9.34g of Triton X-100 and dried overnight at 120 ℃. The obtained dried material was calcined at 500 ℃/4 hours.

13.6g of alumina was obtained. BET was measured after calcining the material at 1100 deg.C/4 hr.

BET of 222 m after 500 ℃/4 h²/g

BET of 6.1m after 1100 ℃/4 hours²/g。

Comparative example C13

Synthesis of Al according to the method described in CN101690890, Using polyethylene glycol as surfactant₂O₃(40%)CeO₂(45%) ZrO₂(12.5%%) La₂O₃(2.5%)

Preparing a mixed metal nitrate solution by: 83.03g of a cerium nitrate solution (CeO)₂27.1%), 24.81g of zirconyl nitrate solution (ZrO)₂25.19%), 3.37g of lanthanum nitrate hexahydrate (La)₂O₃37.1%) and 149.93g of aluminum nitrate nonahydrate (Al)₂O₃13.34%) was dissolved in 400ml of deionized water at room temperature. To the obtained solution was added 20g of polyethylene glycol (Sigma Aldrich) and the mixture was stirred for 30 minutes. Mixing the obtained mixture with ammonia/NH₄HCO₃Aqueous solution of the solutionCoprecipitation and pH adjustment to 8.5. The precipitate was obtained, separated by filtration, washed with deionized water and dried continuously at 120 ℃ for 16 hours. The obtained dried precipitate was calcined at 600 ℃ for 3 hours to obtain 50g of Al₂O₃(40%) CeO₂(45%) ZrO₂(12.5%%) La₂O₃(2.5%) composite oxide.

1050 ℃/5 h, BET 42.5m²/g

1100 ℃/2 h, BET of 36.8m²/g

1100 ℃/20 h, BET:34.3 m²/g。

Comparative example C14

Synthesis of Al according to the method described in CN101690890 Using Polyacrylamide as surfactant₂O₃(40%)CeO₂(45%) ZrO₂(12.5%%) La₂O₃(2.5%)

Preparing a mixed metal nitrate solution by: 83.03g of a cerium nitrate solution (CeO)₂27.1%), 24.81g of zirconyl nitrate solution (ZrO)₂25.19%), 3.37g of lanthanum nitrate hexahydrate (La)₂O₃37.1%) and 149.93g of aluminum nitrate nonahydrate (Al)₂O₃13.34%) was dissolved in 400ml of deionized water at room temperature. To the obtained solution was added 40g of a polyacrylamide solution (50% w/w solution in deionized water, product of Sigma Aldrich) and the mixture was stirred for 30 minutes. Mixing the obtained mixture with ammonia/NH₄HCO₃Aqueous solutions of the solutions were co-precipitated and the pH was adjusted to 8.5. The precipitate was obtained, separated by filtration, washed with deionized water and dried continuously at 120 ℃ for 16 hours. The obtained dried precipitate was calcined at 600 ℃ for 3 hours to obtain 50g of Al₂O₃(40%) CeO₂(45%) ZrO₂(12.5%%) La₂O₃(2.5%) composite oxide.

1050 ℃/5 hours, BET 31.2m²/g

1100 ℃/2 hours, BET 8.4m²/g

1100 ℃/20 h, BET of 24.5m²/g。

Claims (4)

1. Composition comprising Al-, Ce-and Zr-oxides and one or more oxides of rare earth metals other than cerium, characterized in that the aluminium content is 45-55% by weight of the composition calculated as aluminium oxide and the surface area (BET) of the composition after calcination at 1100 ℃ for 2 hours is 55-80m measured according to DIN (Deutsche Industrie Standard) 66131²/g。

2. Composition according to claim 1, characterized in that the cerium content is 5-70% by weight, preferably 5-50% by weight, more preferably 5-30% by weight, most preferably 5-15% by weight of the composition, calculated as cerium oxide.

3. Composition according to claim 1 or 2, characterized in that the zirconium content is 5-70% by weight, preferably 10-60% by weight, more preferably 20-50% by weight, most preferably 30-40% by weight of the composition, calculated as zirconium oxide.

4. Composition according to any one of the preceding claims, characterized in that the rare earth metal different from cerium is chosen from Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, preferably La, Nd.