MXPA99009012A - CERIUM OXIDES, ZIRCONIUM OXIDES, Ce/Zr MIXED OXIDES AND Ce/Zr SOLID SOLUTIONS HAVING IMPROVED THERMAL STABILITY AND OXYGEN STORAGE CAPACITY - Google Patents

Abstract

The production of cerium oxides, zirconium oxides, (Ce, Zr)O2 mixed oxides and (Ce, Zr)O2 solid solutions having improved particle size distribution, surface area, oxygen storage capacity and pore volume by the addition of an additive, such as an anionic or nonionic surfactant, during the formation of the or oxides or precursors thereof.

Description

CERIO OXIDES, CIRCULAR OXIDES, MIXED OC / ZR OXIDES AND SOLID SOLUTIONS OF Ce / Zr HAVING IMPROVED THERMAL STABILITY AND OXYGEN STORAGE CAPACITY DESCRIPTION OF THE INVENTION The present invention relates to the production of cerium oxides, zirconium oxides, mixed cerium and zirconium oxides or solid solutions (also hydroxides and carbonates) having improved thermal stability and oxygen storage capacity. The oxides, hydroxides and carbonates have a fine particle size distribution, a very high surface area, oxygen storage capacity and release capacity, and are useful in many applications including catalytic converters, catalysis for the manufacture of styrene and catalysis for gas exhaust systems. The cerium and zirconium oxides, and particularly the cerium and zirconium oxides (Ce, Zr) 02 and solid solutions, are used for many applications, including catalysts used in automotive catalytic converters and the like. Such oxides are typically formed through known precipitation techniques, which involve the formation of precursors, or solid oxides in a liquid medium. When such oxides are to be used, for example, in catalytic converters, it is desirable to maximize the thermal stability of the compounds, as defined by the stability of the surface area of the material after aging, at high temperature. It is also desirable to maximize the surface area of such mixed oxides in order to provide improved catalytic properties. In addition to the mixed oxides (Ce, Zr) 02, the present invention also relates to cerium oxides, zirconium oxides and mixtures thereof, as well as solid solutions of cerium and zirconium (Ce, Zr) 02 (when the substitution between cerium and zirconium in the network of oxides, as opposed to being two different phases, it is a phase) all of these can be used as catalysts or catalyst supports. The extremely severe vehicle emission standards cause the operating conditions of the exhaust system to increase severely. Most modern gasoline cars are equipped with the so-called three-way catalysts and then treat their exhaust gases. The purpose of this system is to simultaneously convert carbon monoxide, hydrocarbons and nitrogen oxides through a heterogeneous catalyst based on precious metal, so that the air to fuel ratio of the engine is controlled to obtain gas exhaust compositions that guarantee optimal conversions Cerium-zirconium oxides are widely used in three-way catalysts for automotive exhaust treatment. The three-way automotive catalysts consist of precious metals (platinum, rhodium, etc.), promoters and support such as? -alumina. It is known that the addition of Ce02 as a promoter results in a dynamic performance improvement for the reaction of carbon monoxide (CO), nitrogen oxides (NO?) And hydrocarbons (Hcs). However, high temperature conditions of use in an automotive engine lead to significant degradation including the loss of surface area supports, pressure of precious metals supported and the deactivation of aggregate cerium. It is known that cerium oxides and zirconium oxides and mixed cerium and zirconium oxides can be used as a catalyst or a catalyst support. It is also known that a catalyst is generally more effective when the contact surface between the catalyst and the reactants is higher. For this purpose, it is necessary that the catalyst be maintained in a state as much as possible divided, that is, that the solid particles that compose it are as small and individualized as possible. The fundamental role of support, therefore, is to keep the catalyst particles or crystallites in contact with the reagents, in the most possibly divided state. During the extended use of a catalyst support, a reduction occurs in the specific area due to the coalescence of very fine micropores. During this coalescence, part of the catalyst is surrounded by the body of the support and will no longer be in contact with the reagents. An object of the present invention is to provide a method for producing cerium oxides, zirconium oxides, mixed oxides of cerium and zirconium (Ce, Zr) 02 and solid solutions of cerium and zirconium (Ce, Zr) 02 having thermal stability improved, surface area, porosity, and / or storage capacity. The method is preferred for use in the production of cerium oxides, mixed oxides of (Ce, Zr) 02 and solid solutions of (Ce, Zr) 0? which have improved thermal stability, surface area, porosity and / or oxygen storage capacity. Another object of the present invention are compositions of cerium oxide, zirconium oxides, mixed oxides of (Ce, Zr) 02 and solid solutions of (Ce, Zr) Ü having improved thermal stability, surface area, porosity and / or oxygen storage capacity. The oxides, mixed oxides and "solid solutions produced can have very high surface areas, very high oxygen storage capacities and a low particle size.

These and other objects of the present invention will be more readily apparent from the following description. The present invention provides a novel way to improve the thermal stability, surface area, porosity, storage capacity of cerium oxides, zirconium oxides, mixed oxides of (Ce, r) Ü2 and solid solutions of (Ce, Zr) 02 obtained through processes such as precipitation, co-precipitation or thermohydrolysis, introducing an additive, such as an anionic surfactant and / or a nonionic surfactant during the formation of the oxide or precursors thereof. By further washing or impregnation with an alkoxylated compound and / or additive, thermal stability, surface area, porosity and / or oxygen storage capacity can be further improved. All ratios, proportions and percentages herein are by weight unless otherwise indicated. The term "comprising" as used herein means that several components can be used together. Accordingly, the terms "consisting essentially of" and "consisting of" are modalized in the term "comprising". The thermal stability of inorganic compounds can be defined as the stability of the surface area when the material is aged at high temperature. For many applications, particularly catalysis, high surface area materials are highly stable by end users. In accordance with the present invention, mixed cerium and zirconium oxides and solid solutions are produced having improved thermal stability, surface area, porosity, and / or oxygen storage capacity. The invention is also useful for producing cerium oxides, zirconium oxides and mixtures of cerium oxides and zirconium oxides having improved thermal stability, surface area, porosity, and / or oxygen storage capacity. Many methods have been developed for the preparation of oxides of high surface area, mixed oxides and solid solutions. Generally these fall into four basic steps: synthesis of precursors, treatment of precursors before conversion to oxides, conversion of precursors to mixed oxides and post-treatments of mixed oxide material. Synthetic methods for producing precursors for oxides include: precipitation or aqueous co-precipitation, organic co-precipitation, co-precipitation by spray and hydrothermal techniques. These are conventional methods known in the art. The method of the present invention is preferred for use with aqueous precipitation or co-precipitation and hydrothermal techniques. Most preferably, the method of the present invention is used with aqueous precipitation or co-precipitation. Typically, the processes that precipitate hydrated hydroxides in water are acid-based neutralizations or ion exchange reactions. This method typically involves heat treatment to obtain oxides of large surface area. The soluble salts that are frequently used include nitrates, carbonates and halides, which are typically "neutralized" by adding them to a solution of aqueous ammonia, forming metal hydroxides. This is the most commonly used method to prepare precursors for oxide powders. The conventional processes, co-thermohydrolysis and aqueous precipitation, are generally described separately below: Co-fermhydrolysis The first stage of co-thermohydrolysis process involves preparing a mixture, in an aqueous medium, of at least one compound of soluble cerium, preferably a salt, and / or at least one soluble zirconium compound, preferably a salt. The mixture can be obtained either from solid compounds, which are dissolved in water, or directly from aqueous solutions of these compounds, followed by mixing, in any order, of the defined solutions.

Of the water-soluble cerium compounds, an example is the Ce IV salt, such as nitrates including ceric ammonium nitrate, which are suitable for the present invention. Preferably, a cerium nitrate is used. The salt solution of cerium IV may contain some cerium III. However, it is preferred that the salt contain at least about 85% cerium IV. An aqueous solution of cerium nitrate can be obtained by reacting nitric acid with a hydrous ceric oxide, prepared through a standard reaction of a solution of cerium III salt, carbonate, for example, with an ammonia solution in the presence of peroxide. of hydrogen, an oxidizing agent. You can also use solutions of ceric nitrate obtained through the electrolytic oxidation of a waxy nitrate. The aqueous solution of the cerium salt IV may have some free acid, for example, a normality ranging from about 0.1 to about 4 N. In the present invention, it is possible to use either a solution containing some free acid or a pre-neutralized solution through the addition of a base, such as an aqueous solution of ammonia or alkali hydroxides, for example, sodium, potassium, etc. Preferably, an ammonia solution is used to reduce free acidity. In this case, it is possible to define the neutralization rate (r) of the initial solution through the following equation: where ni represents the total number of moles of Ce IV present in the solution after neutralization, n2 represents the number of OH ions "effectively used to neutralize the initial free acidity of the aqueous solution of Ce IV and n3 represents the total number of moles of OH ions" from the added base. When a neutralization case is used, an excess of base can be used in order to ensure complete precipitation of Ce (OH) 4 species. Preferably, r is less than about 1, most preferably about 0.5. The soluble zirconium salts used in the invention can be, for example, zirconium sulfate, zirconyl nitrate or zirconyl chloride. The amount of cerium and zirconium contained in the mixture substantially corresponds to the stoichiometric ratio required to obtain the final desired composition. Once the mixture is obtained, it is then heated. This heat treatment, termed thermohydrolysis, is carried out at a preferred temperature of between about 80 ° C and the critical temperature of the reaction medium, typically between about 80 and about 350 ° C, most preferably around 90 to 200 ° C. The heating step can be carried out under air or under an inert gas such as nitrogen. Any suitable reaction time can be used, usually between about 2 to 24 hours. The heat treatment can be carried out under atmospheric pressure or under any higher pressure such as saturated vapor pressure. When the temperature is higher than the reflux temperature of the reaction medium (usually greater than about 100 ° C), for example between 150 and 350 ° C, approximately, the reaction is carried out in a closed reactor or autoclave. The pressure can be equal to the autogenic pressure and can be correlated to the selected temperature. It is also possible to increase the pressure in the reactor. If required, some additional base may be added directly after the heating step to the reaction medium in order to improve the production of the reaction. After the heating step, a solid precipitate is recovered from the reactor and separated from the mother liquor through any process known in the art, for example, filtration, sedimentation or centrifugation. The precipitate obtained optically can be washed or impregnated with one or more alkoxylated compounds, as will be described later. In another modality, the precipitate is then dried, under air conditions for example, at a temperature ranging from about 80 to 300 ° C, preferably about 100 to about 150 ° C. The drying step is preferably carried out until substantially no weight loss is observed. Conventional drying techniques such as spray drying can be used. After the optional drying step, then the recovered precipitate can be calcined. This allows the formation of a crystalline phase. Usually, the calcination is carried out at temperatures ranging from about 200 to about 1000 ° C. The calcination temperature is typically greater than about 300 ° C, and preferably ranges from about 400 to about 800 ° C. According to the present invention, an additive, for example, a nonionic surfactant or an anionic surfactant, can be added to the salt solutions, the base, the reactor and / or the reaction means. The formation of the hydroxyl (or other precursor) will be in the presence of the additive, preferably during the thermohydrolysis / heating step or the optional additional neutralization step / addition of the base and most preferably during the optional neutralization step.

In a preferred embodiment of the thermohydrolysis, the additive is added to the reactor during the neutralization step. Co-precipitation Aqueous The method of precipitation to aqueous co-precipitation comprises preparing a hydroxyl (also referred to in the art as an aqueous oxide) or carbonate or hydroxycarbonate by reacting a salt solution and a base in the presence of an additive, such as a anionic and / or nonionic surfactant, possibly in the presence of an oxidizing agent, and separating the obtained precipitate, possibly by washing or impregnating it (preferably with an alkoxylated compound), and / or by drying or calcining it. The first step of the co-precipitation process is the preparation of a mixture in an aqueous medium of at least one soluble cerium compound, preferably a salt, at least one soluble zirconium compound, preferably a salt, or both. The mixture can be obtained either from solid compounds which are dissolved in water, or directly from aqueous solutions of these compounds, followed by mixing, in any order, of the defined solutions. According to the present invention, the reaction of the base and the solutions of the serial compound and / or zirconium (at least salt) is carried out in the presence of an additive. The cerium salt solution used can be any aqueous cerium salt solution, in the waxy and / or ceric state, which is soluble under the conditions of preparation, in particular a solution of cerium chloride and cerium nitrate in the state waxy or ceric or a mixture thereof. Suitable water-soluble cerium compounds include cerium III salts and cerium nitrates or halides, for example, chlorides. The zirconium salt solution used can be any aqueous zirconium salt solution, which is soluble under preparation conditions. The soluble zirconium salts used in the invention may be nitrates, sulfates, or halides, for example zirconium sulfate, zirconyl nitrate or zirconyl chloride. Zr (IV) salts can be used. It is preferred to use a cerium or zirconium salt with a high degree of metallic purity, preferably greater than about 90%, preferably greater than about 95% and most preferably above about 99%. It is recognized that the Ce and / or Zr salts may comprise additional elements, such as rare earth elements, for example Pr or La, in varying amounts such as about 2%. The amount of cerium and / or zirconium contained in the mixture corresponds to the stoichiometric ratio required to obtain the final desired composition. Optionally, an oxidizing agent may be used. Among the oxidizing agents that are suitable are solutions of sodium, potassium or perchlorate of ammonium, chlorate, hypochlorite, or persulfate, hydrogen peroxide or air, oxygen or ozone. An oxidizing agent, preferably hydrogen peroxide, can be added to the cerium / zirconium mixture to the cerium or zirconium salt before being mixed together. The amount of oxidizing agent relative to the salts that will be oxidized may vary within wide limits. It is generally greater than stoichiometry and preferably corresponds to an excess. The precipitation can be done through the reaction of the salt solution or solutions and a base solution. The base solution can be added to the cerium and / or zirconium salt solution to precipitate the hydroxides and carbonates or hydroxycarbonates (or the salt solutions can be added to the base solutions). The base may be a solution of ammonia or an alkali hydroxide solution, for example, sodium, potassium, etc., or a solution of sodium, potassium or ammonia carbonate or bicarbonate. The base solution used can be, in particular, an aqueous solution of ammonia or sodium or potassium hydroxide. Preferably an ammonia solution is used.

The normality of the base solution is not a critical factor according to the invention; It can vary within wide limits. A preferred scale is between about 1 and about 5 N, most preferably between about 2 and about 3 N. The amount of the base solution used is determined such that the pH of the reaction medium is preferably greater than about 7. In the case of intermittent precipitation, the amount of base solution added preferably is at least the amount required to precipitate Ce (OH) ¿; and / or Zr (OH) 4. The precipitation is done on an intermittent or continuous basis. In the case of a continuous precipitation, the pH of the reaction is typically maintained between about 7 and 11, preferably between about 7.5 and 9.5. In general, the mixing time in the reaction mixture is a critical factor and can vary within wide limits; generally between about 15 minutes and about 2 hours, they are selected. The residence time of the material in the reactor is typically at least about 15 minutes, preferably at least about 30 minutes. The reaction can be carried out at any suitable temperature, such as room temperature.

After the reaction step, a solid precipitate is recovered from the reactor and separated from the mother liquor through any process known in the art, for example, filtration, sedimentation or centrifugation. The precipitate can be prepared and separated by conventional solid / liquid separation techniques such as decanting, drying, filtration and / or centrifugation. The precipitate obtained afterwards can be washed. Optionally, the precipitate obtained can then be washed or impregnated with one or more alkoxylated compounds, as described below. The next stage of the process is the calcination of the material, either with or without an intermediate drying step. This allows the formation of a crystalline solid solution phase. Usually, the calcination is carried out at temperatures ranging from about 200 to about 1000 ° C. Calcining temperatures greater than about 300 ° C are suitable, preferably ranging from about 350 to about 800 ° C. As previously discussed, the mixed oxides of (Ce, Zr) 02 can be prepared through various processes. The salts of Ce (III) and Zr (IV), nitrates for example, can be mixed together and precipitated by adding a base such as sodium hydroxide or ammonia. Suitable precipitation conditions should be used to obtain the mixed oxide phase after high temperature calcination. This process also requires the use of a base as a precipitation agent. In any case, the precipitating agent is separated from the mother liquor by known techniques such as filtration, decantation or centrifugation. Once washed, the precipitate is either dried at about 120 ° C and calcined at a minimum temperature of about 400 ° C, or directly calcined at the same temperature. The preferred final product is a pure mixed oxide with little or no organic, as they are removed as a result of calcination. Additions: The use of an additive, for example, ethoxylated alcohols or surfactants of an anionic or non-ionic nature, during co-precipitation, hydrothermolysis or the like, in order to improve the thermal stability, surface area, capacity of storage of oxygen and / or porosity of oxides or their precursors, preferably mixed oxides of (Ce, Zr) 02, hydroxides and carbonates. The process is suitable for the production of cerium oxides, zirconium oxides, mixed oxides of (Ce, Zr) 02, solid solutions of (Ce, Zr) 02, and the corresponding hydroxides or carbonates or their hydroxycarbonates, or mixtures thereof. same. The process is preferred for use in the preparation of cerium oxides, mixed oxides of (Ce, Zr) 02, solid solutions of (Ce, Zr) 02, and mixtures thereof and most preferably to prepare mixed oxides of (Ce, Zr) 02, and solid solutions of (Ce, Zr) 02. In the present invention, an additive, such as an anionic or non-ionic surfactant, during the formation of the cerium, zirconium or (Ce, Zr) (mixed or solid solution) oxides or precursors thereof, preferably during co-precipitation. The additive can generally be added to: the metal salt solution, for example, the salt solution Zr or the salt solution Ce, a mixture of the salt solution of Ce and Zr, a water-based solution, a oxidizing agent or the reactor or reaction medium. Optionally, additional alkoxylated compounds or additives may also be added to the precipitate (generally in the form of a wet cake) obtained after the liquid / solid separation or during the liquid / solid separation step. The additives can generally be described by the following general formula: R? - ((CH2) :: - 0) "- R2 wherein Ri and R2 represent a linear or non-linear alkyl, aryl, and / or alkylaryl group, or H or OH or Cl or Br or I; n is a number between about 1 and about 100 and x is a number between about 1 and about 4. Rj and R2 may contain an alcohol group, a CO group, an S-C group, etc. Preferred compounds are those comprising alkoxy groups, particularly methoxy, ethoxy and propoxy groups, which can gene an improvement in thermal stability, surface area, porosity and / or oxygen storage capacity. Suitable anionic and nonionic surfactants for use herein are described in Handbook of Surfactants, M.R. Porter, Blackie & Son Ltd., Glasgow, 1991, pp. 54 to 115, which is incorpod herein by reference. The terms "anionic surfactant", "nonionic surfactant", or "additive" as used herein, encompass mixtures of surfactants as well as mixtures of other types of additives. The additive of the present invention can advantageously be provided in the form of an aqueous solution having a relatively minor amount of the additive, for example, an anionic or nonionic surfactant. The additive preferably comprises less than about 50% by weight of the aqueous solution, and most preferably comprises about 0.1 to 30% by weight of an aqueous solution. A preferred commercially available additive for use herein is sold by Rhéne-Poulenc Inc. under the trade name of IGEPAL® nonionic ethoxylates.

Anionic surfactants to be used include: carboxylates, phosphates, sulfates and sulfonates. Suitable carboxylates have the general formula R-CH2C (0) 0 ~ and include: a) ethoxycarboxylates of the formula: R-0 (CH2CH20) xCH2C00 ~, which includes ether carboxylates of the formula: wherein R is an alkyl or an alkylaryl group, M + can be ammonium, potassium, sodium or triethanolamine, and n "" "can be from about 1 to about 13; b) ether carboxylates of the formula: R? -CH2-C [C (0) 0] (OH) (-R2); and c) sarcosinates of the formula: RC (O) N (CH3) CH-COO. "Phosphates having the general formula: R2P04 ~ e include: a) phosphate esters of the formulas (HO) (OR) P (0) 2_ and (RO) 2P (0) 2 ~ wherein R is an alkyl or alkylaryl group, n is moles of ethylene oxide (and / or propylene oxide) and M is hydrogen, sodium, potassium or other counterion. Suitable sulfates have the general formula: R0S03- and include: a) alcohol sulfates; b) alcohol sulfate ether; and c) sulphated alkanolamine ethoxylate. Suitable sulfonates have the general formula: RS03 ~ and include: a) sulfosuccinates; b) tauratos; c) isethionates: RC (0) CH2CH2S03"d) alkyl benzene sulfonates, e) diester sulfonates and fatty acid, f) fatty acid esters a-sulfo, g) alkyl naphthalene sulfonates, h) formaldehyde naphthalene sulfonates, i) olefin sulfonates;; and j) petroleum sulfonates.

The nonionic surfactants to be used include: acetylenic surfactants; alcohol ethoxylates; alkanolamines; amine oxides; ethoxylated alkanolamines; ethoxylated long chain amines; copolymers of ethylene oxide / propylene oxide (EO / PO); Sorbiton derivatives; ethylene glycol; propylene glycol; glycerol and polyglyceryl esters plus their ethoxylated derivatives; alkylamines; alkylimidazolines; ethoxylated oils and fats; and alkylphenol ethoxylates (alkyl phenols ethoxylates). Preferred nonionic agents include the ethoxylated alkylphenols supplied by Rhéne-Poulenc Inc. under the tradename "IGEPAL" © and include: IGEPAL® CA 720: octylphenol of about 12 EO as represented by the formula: • - IGEPAL® CO 630: ethoxylated polyethylene glycol of nonylphenol or nonifenol of about 9 EO as represented by the formula: In addition, EGEPAL® CO 630 is well characterized in Physio-Chemical Properties of Selected Anionic, Cationic and Nonionic Surfactants, N.M. Van Os et al., Amsterdam, 1993, p. 312-316, 318 and 342, which is incorporated herein by reference. Also useful are non-ionic surfactants EGEPALQ RC, and the nonionic surfactants EGEPAL® DN (dodecylphenol + 5 to 14 EO) which are supplied by Rhéne-Poulenc Inc. Also useful are tri-ethyrylphenols ethoxylates. Other preferred nonionic surfactants are glycol monoethers supplied by Dow Chemical under the tradename "DO ANOL" and include: DOWANOL: ethylene glycol n-butyl ether - DOWANOL DB: diethylene glycol n-butylene ether: DOWANOL TBH: triethylene glycol n-butyl ether and above, / \ / OH Other nonionic surfactants to be used include the alkanolamines which are the simplest members of the alkylamide family of polyoxyethylene. Its formula can be either RjC (O) NH (CH2CH_OH) or RiC (O) NH (CH2CH2OH) or R? C (0) N (CH2CH2OH) 2 wherein Ri represents a linear or non-linear alkyl group comprising from about 1 at about 50 ° C or H. Monoalcoholamines are generally solid, while dialcoholamines are generally liquid. Both types can be used, preferably with co-precipitation. These include those sold by Rhóne-Poulenc Inc. under the trade name "ALKAMIDE" ® and include: - _ K__MIDE LE®: -ALKAMIDE® L203: Other preferred nonionic surfactants include ethoxylated amines such as those sold under the trade name "RHODAMEEN" by Rhéne-Poulenc Inc. and include: Rhodammen VP 532 SPB: ethoxylated seboamines Other nonionic surfactants include amine oxides including those supplied by Rhone-Poulenc Inc. under the tradename "Rhodamox" © and include: - Rhodamox LO: lauryl dimethylamine oxide: CH 3 CH 3 (CH 2) 10- - O CH 3 Other additives are polyethylene glycols. The Polyethylene glycols include: Other suitable additives to be used are carboxylic acids, both mono and dicarboxylic acids. The general formula for a carboxylic acid can be represented as: O I I R-C- H Suitable carboxylic acids are listed as: NAME TRIVIAL STRUCTURE GENERAL NAME MONOCARBOXYLICO Formic H-CO, H Methanoic Acidic Acid CH3-CO2H Ethanoic Acid Propionic CH3-CH: -CO2H Propiric Butyric Acid CH3-CH2-2CO2H Buiaoic Isoburic Acid CH3-CH-CO2H 2-Methyl-Ropanic Acid 1 CH3 Valuable CH3- CH2 -2 CO2H Pentanoic acid Caprico CH3- CH2 ~ 4 CO2H Hexandic acid Caprílico CH3 ~ CH2-6 CO, H Octane acid ico Capric CH3- CH2-3 CO2H Decaeoic acid Lauric CH3- CH2-10 CQ2H Dodecanoic acid Myristic CH3- C__2-12 CO2H Tetradecanoic acid Palmí-ico CH3- C? _- CO2H Hexadecanoic acid DICARBOXYLICO Oxalic HQ, C-CO2H E____dioic acid Malonieo HQ2C-CH2-CQ2H Propandioic Acid Succínieo HQ, C-CH2-: CO2H Butaadioic acid Glutaric HQ2C-CH2-3C02H Pentaadioic acid Adipic H02C-CH2-4C02H Hexapdoic acid Pimelico H02C - = - CH2-3CO2H Heptaadioic acid Subérieo H02C-CH2-6C02H acid? Cta_dioico Azeláico H02C-CH2-7C02H Nonaa acid so co Sebaeic HQ2C-CH2-8C02H Deeaadioic acid. Carboxylate salts can also be used as additives. As previously described, the additives will be present during the formation of cerium hydroxide, oxide, hydroxy carbonate and / or carbonate, zirconium hydroxide, oxide, hydroxy carbonate and / or carbonate, cerium / zirconium hydroxide (Ce, Zr. ), oxide (mixed or solid solution, i.e., one phase), hydroxycarbonate and / or carbonate. (For the addition of the non-ionic ethoxylates and (for example, IGEPAL® surfactants) polyethylene glycols, it is preferred that the ethoxylates be added either to the salt solution or metal solutions (eg Ce, Zr), preferably a aqueous solution of cerium nitrate and / or zirconium nitrate, and / or the base solution, preferably an ammonia solution .. Most preferably, the ethoxylates are added to the nitrate solutions and the ammonia solutions before the reaction. For amine surfactants (eg, ALKAMIDE® surfactants), it is preferred to add a salt solution (s) to the metal (eg, Ce, Zr), preferably a solution of cerium nitrate and / or zirconium nitrate and / or water and / or the oxidizing agent, and mixtures thereof For the addition of the carboxylic acids, addition to the base solution is preferred, preferably addition to a solution of ammonia.

The determination of an effective amount of addition for the additives is within the experience of the technicians. Generally, the additives are added (based on the weight percentage of the reaction media and reagents) from about 1% to about 35, preferably about 2% to about 30% and most preferably about 3% to about 30% For the ethoxylated additives, it is generally preferred to use about 2.5% to about 35%, and preferably about 10% to about 25%. For amide additives, it is generally preferred to use about 1% to about 10% and preferably about 2% to about 5%. An excess of the additive can be used without damaging the benefits of the addition. Optional Washing / Impregnation Most industrial processes that involve precipitation or the creation of a solid in a liquid medium involve a solid / liquid separation state. The filtration, decantation or centrifugation are among the known techniques used for this purpose. After completing the solid / liquid separation, the so-called wet cake comprises precipitated particles and the rest of the mother liquor. In most processes, the mother liquor contains some salts that can contaminate the oxides generated during the next calcination operation. To reduce the amount of contaminants, it is necessary to wash during and / or after solid / liquid separation. In cases where the salts used as starting materials to make the precipitation are soluble in water, the washing is typically carried out with water. The volume and temperature of the water used for washing determine the purity of the material and its thermal stability as well. The process of the present invention optionally includes the use of alkoxylated compounds having more than 2 carbon atoms during the washing or impregnation step in order to improve the thermal stability of cerium and / or zirconium oxides and preferably mixed oxides of ( Ce, Zr) 02 and solid solutions. Suitable alkoxylated compounds for use herein have more than 2 carbon atoms. In the scope of the present invention, the solid oxide material is separated from the liquid through filtration or any other suitable method. In a preferred embodiment the solid, otherwise referred to as wet cake, is washed during a first stage with water to remove the water-soluble salts, nitrates, for example, if the nitrate solutions are the starting materials for the reaction. In a second step of the preferred embodiment, the wet cake is washed or impregnated with a solution containing alkoxylated compounds such as ethoxylated alcohols, organic compounds, ethoxylated polymers such as PEG. Once washed or impregnated, the wet cake is either dried or calcined or directly calcined. The final product is a pure mixed oxide that has substantially no organic, since they are removed during calcination. The alkoxylated compounds of the present invention can be defined by the following formula: R? - ((CH2)? 0) nR wherein Ri and R2 represent linear or non-linear alkyl, aryl, and / or alkylaryl groups, or H or OH or Cl or Br or I; n is a number between 1 to 100 and x is a number from 1 to 4. Ri and R2 may contain an alcohol group. Of the alkyl groups, the methoxy, ethoxy and propoxy groups are preferred, in order to generate an improvement in the thermal stability of the mixed oxides (Ce, Zr) 02 and solid solutions. The alkoxylated compound can be of the formula R? - ((CH2) x-0) n-0H wherein R? Is selected from the group consisting of linear or non-linear alkyl groups having from 1 to 20 carbons and fatty hydrocarbon residues having 8 to 20 carbons, n is from 1 to 100 and x is from 1 to 4. Preferably, n is from 12 to 40 and x is from 1 to 3. Most preferably x is from 2. The alkoxylated compound can be of the formula : H (OCH2) nOH or H (OEt) nOH, Wherein the average of n is from 1 to 100. Examples of suitable alkoxylated compounds can be of the formulas: where the average of x is 9 or 4 to 15; where the average of x is 12; Commercially available alkoxylated compounds suitable for use are sold by Rhéne-Poulenc Inc. under the trade names of IGEPAL® CO 630, IGEPAL® CA 720, ALKAMIDE® and ALKAMIDE® L203. The alkoxylated compound may alternatively be of the formula:) -0H, wherein R2 and R3 are the same or different and are independently selected from the group consisting of hydrogen and linear or non-linear alkyl groups having from 1 to 20 carbons, n is from 1 to 100 and x is from 1 to 4. Preferably, n it is from 12 to 40 and x is from 1 to 3. Most preferably x is 2. The alkoxylated compound can also be of the formula: R40- ((CH2) xO) nH, wherein R is selected from the group consisting of groups linear or non-linear alkyl having from 1 to 20 carbons, n is from 1 to 100 and x is from 1 to 4. Preferably, n is from 12 to 40 and x is from 1 to 3. Most preferably, n is 3 and x is from 2. The alkoxylated compound can furthermore be of the formula: R5-S- ((CH2) x0) nH wherein R5 is selected from the group consisting of linear and non-linear alkyl groups having from 1 to 20 carbons, n is 1 at 100 and x is from 1 to 4. Preferably, n is from 12 to 40 and x is from 1 to 3. Most preferably x is 2.

The alkoxylated compound can also be of the formula: wherein Rg is selected from the group consisting of linear and non-linear alkyl groups having from 1 to 20 carbons, n is from 1 to 100 and m is from 0 to 300, preferably from 0 to 100.

Preferably, n is from 12 to 40 and m is from 1 to 40. The alkoxylated compound can alternatively be of the formula: CH 3 HO (CH: CH2O) ß (CH2CHO) m (CH2CH, OVH) wherein o is 0 to 300, m is 0 to 300 and p is 0 to 300. The alkoxylated compound can also be of the formula: wherein R is selected from the group consisting of linear and non-linear alkyl groups having from 1 to 20 carbons, n is from 1 to 100 and x is from 1 to 4. Preferably, n is from 4 to 40 and x is from 1 to 3. Very preferably x is 2. The alkoxylated compound may also be of the formula: CH3 CH3 i i HO-. { CH, CH2O)? N (CH2CH2O) p (CH2CHO) q-H, wherein m is from 0 to 300, p is from 0 to 300 and q is from 0 to 300 and has an average molecular weight of from about 40 to about 8000. The alkoxylated compound may comprise, or be derived from, compounds as listed below: polyoxyalkylenated (polyethoxy-ethylated, polyoxypropylenated, polyoxybutylenated) alkylphenols wherein the alkyl substituent is Cg-C 2 and contains from 5 to 25 oxyalkylene units; examples include Tritons X-45, X-114, X-100 and X-102, sold by Rohm & Haas Co .; - glucosamide, glucamide and glycerolamide; - Polyoxyalkylenated Cg-C22 aliphatic alcohols containing 1 to 25 units of oxyalkylene (oxyethylene, oxypropylene); examples include Tergitol 15-S-9 and Tergitol 24-L-6, sold by Union Carbide Corp .; Neodol 45-9, Neodol 23-65, Neodol 45-7 and Neodol 45-4, sold by Shell Chemical Co .; and Kyro KOB sold by Procter & Gable Co .; - the products resulting from the condensation of ethylene oxide, the compound resulting from the condensation of propylene oxide with propylene glycol, such as Pluronics sold by BASF; - the products resulting from the condensation of ethylene oxide, the compound resulting from the condensation of propylene oxide with ethylenediamine, such as Tetronis sold by BASF; - amine oxides such as dimethylamine oxides (C? 0-Cg alkyl) and diethyldihydroxyethylamine oxides (C6-C22 alkoxy); - the alkyl polyglycosides described in U.S. Patent 4,565,647; - C6 ~ C2o fatty acid amides; - C6-C2o alkamides, preferably used at low concentrations; - ethoxylated fatty acids; and - ethoxylated amines. The alkoxylated compound of the present invention can advantageously be provided in the form of an aqueous solution having a relatively lower amount of the alkoxylated compound. The alkoxylated compound preferably comprises less than about 50% by weight of the aqueous solution, and most preferably comprises about 0.1 to 30% by weight of the aqueous solution. A commercially available, preferred compound for use is sold by Rhéne-Poulenc Inc. under the trade name IGEPAL® CA 720 surfactant.

The alkoxylated compounds can also be used as additives as described above. Conversely, the additives described above can be used in the washing or impregnation of carbonates, hydroxides or oxides of cerium, zirconium, mixed or solid solutions of Ce / Zr. Preferred additives to be used are carboxylic acids, carboxylate salts and anionic surfactants. One embodiment of the present invention is washing or impregnation using the additives, preferably additives that are not ethoxylated. Impregnation is the addition of the alkoxylated compound and / or additive, preferably with mixing, to the oxide, hydroxide or carbonate, preferably in the form of a wet cake, followed by calcination. The preferred impregnation surfactant is an ethoxylated alkylphenol. The alkoxylated compound or additive is usually added to an amount equal to the total weight of the oxide, hydroxide, or carbonate in the wet cake. The material is then calcined at a temperature high enough to ensure the removal of carbonaceous remnants of the oxide, hydroxide or carbonate. For example, instead of being present during the formation, a carboxylic acid such as lauric acid may be used in the washing or impregnation of a cerium, zirconium hydroxide, oxide or carbonate, mixed solutions of cerium / zirconium or solids. A preferred embodiment could be a carboxylic acid dissolved in aqueous ammonia or the like for washing or impregnation. The preferred molar ratio scale for ammonia (NH3) to carboxylic acid is from about 0 to about 4, preferably about 1.5 to 3.5. Oxides and Solid Solutions The mixed oxides or solid solutions produced using the additives typically have a weight ratio of Ce02 to Zr02 from about 5:95 to about 95: 5, and preferably about 95: 5 to about 40:60. Mixed oxides and solid solutions, preferably being rich in cerium, have a very high surface area, for example, greater than 25 pr / g, preferably greater than about 30 m2 / g and most preferably greater than about 35 irr / g after of the calcination of approximately 900 ° C for 6 hours. The term "cerium rich" refers to mixed cerium / zirconium oxides having the formula (CexZr? _: :) 02 where x is greater than or equal to about 0.5. Mixed oxides and solid solutions, preferably being rich in cerium, also have a very high oxygen capacity, for example, greater than about 2, preferably greater than about 2.6 ml 02 / g after calcination at about 500 ° C during around 2 hours.

The surface area of the mixed oxides and oxides produced according to the present invention is designated B.E.T. determined by the nitrogen uptake according to the standard procedure of ASTM D 3663-78 established from the method by BRUNAUER-EMMET-TELLER described in Journal of the American Chemical Society, 60, 309 (1938). The thermal stability is designated as the surface area of any inorganic powder material after aging at a given temperature for a certain time. In the present invention, 10 g of material was calcined in a muffle furnace for about 6 hours around 900 ° C. After this aging step, the surface area of the material was measured by the previously described method. The oxides produced with the addition of additives as described herein provide cerium oxide, zirconium oxides, cerium / zirconium mixed oxides or solid cerium / zirconium solutions having total pore volumes greater than about 0.5 ml / g. after calcination at about 500 ° C for about 2 hours, preferably around 0.5 to 1 ml / g after a calcination of about 500 ° C for about 2 hours, and most preferably greater than about 0.6 or 0.8 after of the calcination at about 500 ° C for about 2 hours.

The following examples illustrate various aspects of the invention and are not intended to limit the scope thereof. Example 1 A mixed oxide composition of: Ce02 = 80% / p Zr02 = 20% / p was prepared using a co-precipitation method and a solution of cerium and zirconium nitrate. By reacting the various salts in stoichiometric amounts and adding ammonia to the mixed nitrates to reach a pH of about 9, the mixed hydroxides, corresponding to approximately 30 g of the dry rare earth oxides (REO) were precipitated out of solution and they filtered in a Büchner filter. The cake was washed with approximately 12.5 ml of deionized water per gram of oxide, then calcined for about 2 hours at 500 ° C. The thermal stability of the product was evaluated after calcination under air in a muffle furnace at approximately 900 ° C for 6 hours. The surface area was measured at approximately 22 m2 / g by the method of B.E.T. (Micromeretics Gemini 2360). Example 2: The experiment described in Example 1 was repeated. However, an IGEPAL® CA 720 surfactant (Octylphenol containing 12 EO groups) was added during the preparation of the mixed Ce / Zr oxide. The molar ratios of surfactant to moles of total metal are about 1.11. The surfactant was added to the nitrate metal solution and the ammonia solution. The concentration of the pure surfactant is approximately 20% in the nitrate solution and approximately 30% in the ammonia solution. The dried cake obtained was washed with approximately 12.5 ml of deionized water per gram of oxide, and calcined as in Example 1. The surface area measured after calcination under air at about 900 ° C for about 6 hours is of approximately 33 m2 / g. The increase is approximately 47.5% compared to the product made without surfactant. Example 3 The conditions used in Example 1 were used again. However, the mixed oxide was prepared in the presence of an Alkamide LE® surfactant, which is an alkanolamine with a Cu chain. The amount of surfactant added is 0.13 moles per mole of metal. All the alkanolamide was added to the mixed nitrate solution. The surface area measured after calcination under air at about 900 ° C for about 6 hours is around 35 m2 / g. This example further demonstrates the effect of a small amount of surfactant having on the improvement of thermal stability.

Example 4: In this example, a mixed oxide rich in Zr was prepared. The stoichiometric amounts of the cerium nitrate solution and the zirconium nitrate solution were mixed to obtain a product with the following composition: 80% / p Zr02 and 20% / p Ce02. The mixed oxide was precipitated using the procedure described in Example 1. The surface area after calcination under air at about 900 ° C for 6 hours is about 32 m2 / g. Example 5 The conditions used in Example 4 were used. However, in this case, the mixed oxides were precipitated in the presence of the surface-active agent IGEPAL "'CA 720 (Aromatic ethoxylated phenol-non-ionic) The amount of surfactant used is 0.96 moles per mole of metal The surfactant IGEPAL01 CA 720 was added to both the ammonia solution (surfactant concentration of approximately 20%) and the nitrate solution (surfactant concentration of approximately 22% by weight). The thermal stability after calcination under air at 900 ° C for 6 hours is about 38 m2 / g, indicating an improvement of about 19% compared to the product made without surfactant.

Example 6 Oxygen storage capacity (OSC) was measured in the sample obtained in Example 1. The OSC was obtained using alternate pulses of CO and 02 in He passed through the mixed oxide bed at approximately 400 ° C with the order to stimulate rich and poor conditions in an engine. CO was diluted to about 5% in He and 02 to about 2.5% in the same inert gas. The continuous flow rate of He is about 10 [deg.] H -1 and the volume of catalyst is about 0.1 cm. 02 were measured, CO and C02 using gas chromatography. The OSC of the alternate pulses was evaluated. The result is approximately 1.6 ml 02 / g mixed oxide (± 0.1). Example 7 The OSC was measured in the sample prepared according to Example 2 precipitated in the presence of an EO surfactant. The result is approximately 2.4 ml 02 / g mixed oxide (± 0.1). The addition of surfactant had a significant effect on the increase of OSC. Example 8 A cerium dioxide was prepared but by adding ammonia to a cerium nitrate solution in order to reach a pH of about 9.0. The precipitated hydroxide was filtered on a Buchner filter and washed with approximately 12.5 ml of deionized water per gram of oxide. The surface area measured after calcination under air at approximately 900 ° C for 6 hours is around 2 m2 / g. Example 9 Example 8 was repeated. However, precipitation was performed in the presence of an Alkamide LE® surfactant. The concentration of surfactant in the cerium nitrate solution is about 2% by weight. The surface area measured after calcination at approximately 900 ° C for 6 hours is approximately 4 m2 / g. This demonstrates the improvement of the thermal stability of pure ceria using a surfactant in the process. Example 10 A co-thermohydrolysis process was performed, as described above. This example illustrates the preparation of a mixed oxide of cerium-zirconium (Ceo, 5Zro.25? 2). A solution of ceric nitrate and zirconyl nitrate was combined in the stoichiometric proportions required to obtain the desired composition. The nitrate solution was preneutralized with NH0H to decrease the acidity. The concentration of the mixture (expressed in oxides of different elements) was adjusted to approximately 80 g / 1. The mixture was heated in an autoclave reactor at approximately 150 ° C for about 4 hours, for the pulp which was obtained in this way approximately 27 g of the surfactant Alkamide LE was added. "A solution of ammonia was added to the previously described mixture until the pH was greater than about 8.5.The reaction mixture was heated to boiling for about 2 hours. the liquid from the solid, the resulting solid was resuspended and heated to about 100 ° C for about 1 hour.The product was then filtered and calcined at about 600 ° C for about 2 hours. measured at approximately 32 pr / g after calcination under air at approximately 900 ° C for about 6 hours. The surface area was measured at approximately 19 g after calcination under air at approximately 900 ° C for 6 hours. Example 11 Using a mercury porosimeter supplied by Micromeritics, samples of mixed oxides of Ce02Zr02 80/20% by weight prepared by co-precipitation were evaluated for a pore volume (measured after calcination under air at approximately 500 ° C during about two hours): Sample A: Prepared according to the co-precipitation method of Example 1 without additive of surfactant and achieve a total pore volume, ml / g of about 0.35. Sample B: Prepared according to Example 3 through the addition of a nonionic surfactant, the nonionic surfactant Alkamide LE® (Lauramide DEA) supplied by Rhone-Poulenc Inc., achieves a total pore volume, ml / g of approximately 0.88. Sample C: prepared according to Example 2 through the addition of a nonionic surfactant, the surfactant IGEPAL® CA-720 (Octylphenol aromatic ethoxylate) supplied by Rhéne-Poulenc Inc., achieves a total pore volume ml / g of approximately 0.72. Example 12 Using a co-precipitation method, a solution of cerium and zirconium was added to an aqueous solution containing ammonia and lauric acid, to prepare a mixed oxide of the composition: 80% / p Ce02 and 20% / p Zr02. By reacting the various salts in stoichiometric amounts and adding to a solution of ammonia, which contains lauric acid, the hydroxides, corresponding to 22.5 g of dry earth oxide (REO), were precipitated out of the solution and filtered over a funnel of Büchner. The ratio of moles of lauric acid / moles of total metal is 0.2. The lauric acid is. added only to the ammonia solution. The wet cake obtained was washed with 12.5 ml of deionized water per g of oxide and calcined in air for about 2 hours at about 500 ° C. The thermal stability of the product was evaluated after calcination under air in a muffle furnace at approximately 900 ° C for 6 hours. The surface area was measured at approximately 34 m2 / g through the B.E.T method. (Micromeritics Gemini 2360). The increase is approximately 49.0% compared to the product made without lauric acid. Lauric acid can be represented by the formula: CH 3 (CH 2) 10 C (O) OH. Example 13 The thermal stability was measured for two samples, measuring the surface area through the method of B.E.T.

(Micromeritics Gemini 2360 Norcross, Ga.) Of three samples that were aged (under air) for approximately 6 hours at 900 ° C, at approximately 1000 ° C, and approximately 1100 ° C. The curves are shown below in Figure 1. Sample A: prepared according to the co-precipitation method of Example 1 without additive. Sample B: Prepared according to Example 2 through the addition of a nonionic surfactant, the surfactant Igepal® CA-720 (Octylphenol Aromatic Ethoxylate) supplied by Rhéne-Poulenc Inc.

Figure 1 - -Show fi - "--Sample ß temperature (C)

Claims (36)

1. CLAIMS 1. A process characterized in that it comprises the reaction of a solution of cerium, zirconium solution, a base, optionally an oxidizing agent, and an additive selected from the group consisting of: a) anionic surfactants; b) nonionic surfactants; c) polyethylene glycols; d) carboxylic acids; and e) carboxylate salts. The process according to claim 1, characterized in that it comprises the step of washing or impregnating with an alkoxylated compound and / or an additive selected from the group consisting of: a) anionic surfactants; b) carboxylic acids; and c) carboxylate salts. 3. The process according to claim 1, characterized in that the reaction is an aqueous precipitation or co-precipitation. 4. The process according to claim 1, characterized in that the reaction is co-thermohydrolysis. 5. The process according to claim 1, characterized in that the additive is represented by the formula: R? - ((CH2) x-0) n-R2 wherein Ri and R2 represent a linear or non-linear alkyl, aryl and / or alkylaryl group, or H or OH or Cl or Br or I; n is a number between about 1 and about 100; x is a number from about 1 to about 4 and Ri and R2 may contain an alcohol group, a CO group or an S-C group. 6. The process according to claim 5, characterized in that the additive comprises a methoxy, ethoxy or propoxy group. The process according to claim 1, characterized in that the anionic surfactants are selected from the group consisting of carboxylates, phosphates, sulfates, sulfonates and mixtures thereof. 8. The process in accordance with the claim 7, characterized in that the nonionic surfactants are selected from the group consisting of: acetylenic surfactants, alcohol ethoxylates, alkanolamides, amine oxides, ethoxylated alkanolamides, ethoxylated long chain amines, ethylene oxide / propylene oxide copolymers ( EO / PO) derivatives of sorbitan; ethylene glycol, propylene glycol, glycerol and polyglyceryl esters plus their ethoxylated derivatives; alkylamines, alkylimidazolines, ethoxylated oils and fats; alkylphenol derivatives and mixtures thereof. 9. The process according to claim 8, characterized in that the nonionic surfactants are selected from the group consisting of: a) octylphenols of about 12 EO such as those represented by the formula: b) polyethylenic glycols ethoxylated with nonylphenol of about 9 EO represented by the formula: c) nonylphenols having from about 5 to about 14 EO; d) tristyrylphenol ethoxylates; e) ethylene glycol n-butyl ethers represented by the formula: f) diethylene glycol n-butyl ethers represented by. the formula: Bu ', ^^ OH g) n-butyl ethers of triethylene glycol represented by the formula: h) alkanolamides represented by the formulas OR üW i) ethoxylated bamboamines represented by the formula: , (CH2CH20) -H R-N (CH2CH20) y-H j) Lauryl dimethylamine oxides represented by the formula; CH3 CH3 (CH2) 10-N? -O CH3 10. The process according to claim 7, wherein the anionic surfactants are selected from the group consisting of: a) ethoxycarboxylates of the formula: R-0 (CH2CH20) 3CH2COO, which includes ether carboxylates of the formula: wherein R is an alkyl or alkylaryl group, M + can be ammonium, potassium, sodium or triethanolamine, and n can be from about 1 to about 13; b) carboxylate ester of the formula: R ~ CH2-C [C (0) 0] (-R2); c) sarcosinates of the formula: R-C (O) N (CH3) CH2C00; d) phosphate esters of the formulas (OH) (OR) (O) 2 Y (RO) 2P (0) 2 O RO (CH 2 CH, O) n O OM RO (CH2CH2O) n OM where R is an alkyl or alkylaryl group, n is moles of ethylene oxide (and / or propylene oxide) and M is hydrogen, sodium, potassium or other counterion; e) alcohol sulfates; f) alcohol ether sulfates; g) sulfated alkanolamide ethoxylate; h) sulfosuccinates; i) tauratos; j) isethionates; R-C (O) CH2CH2S03 k) alkylbenzenesulfonates; 1) fatty acid and diester sulfonates; m) α-sulfo fatty acid esters; n) alkylnaphthalene sulfonates; o) formaldehyde naphthalenesulfonates; p) olefin sulfonates; and q) petroleum sulfonates. The process according to claim 1, characterized in that the ethoxylated nonionic surfactants and the polyethylene glycols are added to the salt solution, base solution or both before the reaction. The process according to claim 9, characterized in that the alkanolamides are added to the solutions of salt, water, oxidizing agent and any combination thereof before the reaction. 13. The process according to claim 1, characterized in that the carboxylic acids are added to the base solution before the reaction. The process according to claim 1, characterized in that the additive is added based on the percentage by weight of the reaction media and reagents of about 1% to about 35%. 15. A method for improving the thermal stability, surface area, porosity, and / or storage capacity of cerium oxides, zirconium oxides, mixed oxides of (Ce, Zr) 02 or solid solutions of (Ce, Zr) 02 preparing a cerium hydroxide, zirconium hydroxide, mixed cerium / zirconium hydroxide or hydroxide of a cerium / zirconium solid solution in the presence of an additive selected from the group consisting of: a) anionic surfactants; b) nonionic surfactants; c) polyethylene glycols; d) carboxylic acids; and e) carboxylate salts. 16. The method according to claim 15, characterized in that the process for the preparation is co-thermohydrolysis or an aqueous co-precipitation. 17. Cerium oxides, zirconium oxides, mixed oxides of (Ce, Zr) 02 or solid solutions of (Ce, Zr) 02 characterized in that they have a toral pore volume greater than about 0.5 ml / g after calcination under air at about 500 ° C for about 2 hours. 18. The oxide according to claim 17, characterized in that it has a total pore volume greater than about 0.8 ml / g after calcination under air at about 500 ° C for 2 hours. _ 19. A mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 characterized in that it has a total pore volume greater than about 0.5 ml / g after calcination under air at about 500 ° C during approximately 2 hours. 20. A mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 characterized in that it has a surface area greater than about 25 m2 / g after the. Calcination under air at approximately 900 ° C for about 6 hours. 21. The mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 according to claim 20, characterized in that the surface area is greater than about 30 m / g after calcination under air at approximately 900CC for approximately 6 hours. 22. A mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 characterized in that it has an oxygen storage capacity greater than about 2 ml of 02 / g after calcination under air at about 900 ° C during approximately 2 hours. 23. The mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 according to claim 22, characterized in that the mixed oxide or solid solution is rich in cerium. 24. A mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 characterized in that it has a) a total pore volume greater than about 0.5 ml / g after calcination under air at about 500 ° C for about 2 hours. b) a surface area greater than approximately 25 m2 / g after calcination under air at about 900 ° C for about 6 hours; and c) an oxygen storage capacity greater than about 2 ml 02 / g after calcination under air at about 900 ° C for about 2 hours. 25. The mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 according to claim 24, characterized in that the total pore volume is greater than about 0.6 ml / g after calcination at about 500 ° C for about 2 hours; the surface area is greater than about 30 irr / g after calcination at about 900 ° C for about 6 hours; and the oxygen storage capacity is greater than about 2.6 ml 02 / g after calcination at about 500 ° C for about 2 hours. 26. A mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 characterized in that it has an oxide storage capacity greater than about 2 ml 02 / g after calcination at about 900 ° C for about 2 hours, a total pore volume greater than about 0.5 ml / g after calcination at about 500 ° C for about 2 hours, or a surface area greater than about 25 m2 / g after calcination at about 900 ° C for about 6 hours, the mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 prepared through a process comprising the step of preparing a mixed oxide precipitate of (Ce, Zr) 02 or a hydroxide of a solid solution of (Ce, Zr) 02 by reacting a solution of the cerium salt, a zirconium salt solution, a base, an additive selected from the group consisting of: a) anionic surfactants; b) nonionic surfactants; c) polyethylene glycols; d) carboxylic acids; and e) carboxylate salts; and optionally an oxidizing agent. 27. A process characterized in that it comprises the step of washing or impregnating hydroxides of cerium, oxides, hydroxycarbonates or carbonates; zirconium hydroxides, oxides, hydroxycarbonates or carbonates, mixed cerium / zirconium hydroxides, oxides, hydroxycarbonates or carbonates; or cerium / zirconium hydroxides, oxides, hydroxycarbonates or carbonates in solid solutions with an additive selected from the group consisting of: anionic surfactants; carboxylic acids; and carboxylate salts. 28. A dehydrogenation catalyst characterized in that it comprises: an active support selected from the group consisting of: mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 having: a) a larger total pore volume about 0.5 ml / g after calcination under air at about 500 ° C for about 2 hours; b) a surface area greater than about 25 m2 / g after calcination under air at about 900 ° C for about 6 hours; and c) an oxide storage capacity greater than about 2 ml 02 / g after calcination under air at 900 ° C for about 2 hours. 29. The mixed oxide of (Ce, Zr) 02 or solid solution of (Ce, Zr) 02 according to claim 28, characterized in that the total pore volume is greater than about 0.6 ml / g after calcination at about 500 ° C for about 2 hours; the surface area is greater than about 30 rrr / g after calcination at about 900 ° C for about 6 hours; and the oxygen storage capacity is greater than about 2.6 ml 02 / g after calcination at about 500 ° C for about 2 hours. A method for preparing styrene characterized in that it comprises the step of converting ethylbenzene to styrene using a dehydrogenation catalyst comprising an active support prepared through the process comprising the steps of: washing or impregnating hydroxides of cerium, oxide, hydroxycarbonates or carbonates; zirconium hydroxides, oxides, hydroxycarbonates or carbonates; mixed cerium / zirconium hydroxides, oxides, hydrocarbonates or carbonates; or cerium / zirconium hydroxides, oxides, hydroxycarbonates or carbonates, solid solutions, with an additive selected from the group consisting of anionic surfactants: carboxylic acids; and carboxylate salts. 31. A method for preparing styrene characterized in that it comprises the step of converting ethylbenzene to styrene using a dehydrogenation catalyst comprising an active support selected from the group consisting of mixed oxides of (Ce, Zr) 02 or solid solution of (Ce, Zr) ) 02 having: a) a total pore volume greater than about 0.5 ml / g after calcination under air at about 500 ° C for about 2 hours; b) a surface area greater than about 25 m ~ / g after calcination under air at about 900 ° C for about 6 hours; and c) an oxide storage capacity greater than about 2 ml 02 / g after calcination under air at 900 ° C for about 2 hours. 32. A method of catalysis for exhaust gas systems characterized in that it comprises the steps of: reacting a solution of cerium, zirconium solution, a base, an additive selected from the group consisting of: a) anionic surfactants; b) nonionic surfactants; c) polyethylene glycols; d) carboxylic acids; and e) carboxylate salts; and optionally an oxidizing agent. 33. A method of catalysis for exhaust gas systems characterized in that it comprises: mixed oxides of (Ce, Zr) 02 or solid solutions of (Ce, Zr) 02 having: a) a total pore volume greater than about 0.5 ml / g after calcination under air at about 500 ° C for about 2 hours; b) a surface area greater than approximately 25 m / g after calcination under air at about 900 ° C for about 6 hours; and c) an oxide storage capacity greater than about 2 ml 02 / g after calcination under air at 900 ° C for about 2 hours; and mixtures thereof. 34. A method of catalysis for exhaust gas systems characterized in that it comprises a product of the process comprising the steps of: washing or impregnating cerium hydroxide, oxides, hydroxycarbonates or carbonates; zirconium hydroxides, oxides, hydroxycarbonates or carbonates; mixed cerium / zirconium hydroxides, oxides, hydroxycarbonates or carbonates; or solid solutions of cerium / zirconium hydroxide, oxides, hydroxycarbonates or carbonates with an additive selected from the group consisting of: anionic surfactants; carboxylic acids; and carboxylate salts. 35. A catalytic converter characterized in that it comprises the product of the process comprising the steps of: reacting a solution of cerium, zirconium solution, a base, an additive selected from the group consisting of: a) anionic surfactants; b) nonionic surfactants; c) polyethylene glycols; d) carboxylic acids; and e) carboxylate salts; and optionally an oxidizing agent. 36. A catalytic converter characterized in that it comprises the product of the process comprising the steps of: washing or impregnating cerium hydroxide, oxide, hydrocarbonate or carbonate; zirconium hydroxide, oxide, hydroxycarbonate or carbonate; mixed cerium / zirconium hydroxides, oxides, hydrocarbonates or carbonates; or solid solutions of cerium / zirconium hydroxides, oxides or carbonates with an additive selected from the group consisting of: anionic surfactants, carboxylic acids; and carboxylate salts.