JPS6332728B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a colloidal cerium dioxide dispersion in an organic liquid. [Prior Art] It is well known that metal soaps are used as drying agents in paint and varnish formulations to accelerate the drying of unsaturated oils such as linseed oil and unsaturated synthetic resins such as alkyd resins. It is. Metal soap cations are thought to actively catalyze oxidation and polymerization processes, while anions act as carriers for the metal, rendering it oil-soluble, water-insoluble, and compatible with other components of the paint. . British Patent No. 1236085 to Steele and Smith, published June 16, 1971, includes:
Therefore, as long as the resulting soap is oil-soluble, the acid 1
It has been observed that it is clearly economically advantageous to introduce as much metal as possible per unit. Large amounts of metal loading are achieved by using "basic" soaps in which the ratio of metal to acid is greater than the stoichiometric ratio. For example, 2RCOOH + PbO → (RCOO) ₂ Pb + H ₂ O - Stoichiometric ratio 2RCOOH + 2PbO → RCOOPb・O・PbOOCR
+H ₂ O - "Basic" Soap However, the above British patent states that in the production of this type of "basic" soap, the resulting soap and oil solution is very viscous and difficult to handle, especially in paint compositions. It has been criticized for the difficulty of the compounding operations required to manufacture the product. According to the above mentioned British patent, this high viscosity can be reduced by reacting a reaction mixture of carboxylic acids or their alkali metal salts with polyvalent metal salts or metal oxides which provide the metal cations of the paint drying agent. can. The polyvalent metal salts or metal oxides used in this method are aluminium, barium, copper, iron or magnesium salts or oxides, preferably zirconium, zinc or manganese salts or oxides, most preferably It is a salt or oxide of calcium, lead or cobalt. Using mixtures of different metal soaps, as long as certain soaps, such as zinc or calcium soaps, do not act as desiccants on their own, but have a synergistic effect with other soaps, such as cobalt or lead soaps. It is recommended that you do so. There is no mention of rare earth metal soaps or cerium soaps. Turner, published October 14, 1964;
British Patent No. 972,804 to Downes and Herson discloses aluminum or boron, one or more divalent metal elements or metal residues, wherein the aluminum or boron and the divalent metal atom are bonded via an oxygen atom. Metal organic soaps containing one or more carboxylic acid residues have been described. Such metal organic compounds are obtained by condensing an alkoxide or aryl oxide of aluminum or boron with an acyl oxide of a divalent metal or metal residue. Divalent metals and metal residues include magnesium, calcium, strontium, barium, zinc, cadmium, iron, cobalt, nickel, lead, copper, manganese and silconyl residues, but rare earth metals such as cerium or There is no mention of the base.
The metal content of the product is high, with organic acid residues present in a ratio of 0.5 to 1.5 equivalents per metal atom. As a result, the products have a higher acid-accepting capacity than traditional metal soaps, therefore they are
This is an example of the type of "basic" soap described in US Pat. No. 1,236,085. Collins and Pearl British Patent No. 1430347, published March 31, 1976, includes:
Common or "basic" metal soaps of synthetic carboxylic acids were previously compounds similar to those derived from natural acids, but as a variety of synthetic carboxylic acids became available, they were used to create mutually isomeric compounds. It is stated that they have provided more or less homogeneous compounds even though they are not physically related. Collins et al. proposed to improve upon the prior art by using different preparation methods and different compositions to obtain desiccant products or metal soaps with different properties. Collins et al.'s conventional methods include fusion or precipitation methods. The reactant acid can be dissolved in a suitable inert solvent, usually a hydrocarbon solvent such as mineral spirits, into which the desired metal compound is then added, usually a suitable oxide or inorganic compound or salt. The reaction is accelerated by heating at an appropriate temperature. This results in a hydrocarbon solution of the soap, from which the solvent can be distilled off to increase the metal concentration to the desired value. The method of Collins et al. uses a carboxylic acid or acid mixture, which may be a natural product or a derivative thereof or a synthetic product, which is mixed with a glycol ether, glycol or other similar polyol, and a metal compound such as a metal powder. or metal oxides, hydroxides, acetates or carbonates are added. The mixture is then heated at a temperature between 65°C and 143°C until the metal compounds disappear, after which water is distilled off, the reaction mixture is filtered, and excess glycol and glycol ether are distilled off to obtain the appropriate desired concentration. or to state. Although the equivalent ratio of metal to glycol ether or polyol is greater than 0.5, it must be ensured that a significant amount of glycol ether or polyol is retained in the product if it is desired to maintain the fluidity of the product. The equivalent ratio of the metal part to the acid part is 1.0 or more, and when the metal is lead, it is 1.5 or more, and for lead, a ratio of 2 or more is easily obtained. In addition to lead soaps, barium, nickel and manganese soaps as well as cobalt soaps have been produced by this method, but there is no mention of rare earth metal soaps such as cerium. The patentees of the above-mentioned patents claim that their products and methods are used solely for reducing the viscosity of lead carboxylates, as described in UK Patent No. 1,148,998, or as described in Huishier's US Pat. No. 2,007,553. This is clearly different from simply changing the amount of glycol or glycol ether used to stabilize the soap solution. These products are commercially available from Assignee Mooney Chemicals. French Patent No. 7622426 of Gamlen Eurob published on February 17, 1978 and
British patent application published on July 9, 1980
1571210 describes organic cerium salts soluble in organic solvents characterized by a ratio of the number of acid equivalents to the number of cerium atoms of 0.2 to 1. In this case, "acid equivalent" means the number of acid molecules when the acid used is monofunctional; in the case of diacids or triacids, this figure must be multiplied by 2 or 3; More generally, in the case of multiple acids, it is necessary to multiply by the number of acid functions. The cerium compounds obtained in this way require only smaller amounts than previously used for the same effectiveness, and despite the high metal concentrations reaching up to 500 g/ The result is a fluid solution that is easy to handle and remains completely soluble in the hydrocarbon medium. Organic acids are RCOOH, RSO ₃ H, ROSO ₃ H,
It may be either ROPO ₃ H ₂ or (RO) ₂ PO ₂ H (wherein R represents a hydrocarbon residue having 7 or more carbon atoms). The organic acid residues may be straight-chain or branched aliphatic or cycloaliphatic residues, which may optionally be alkylated. Alternatively, the organic acid residue may be an aromatic residue, which may optionally be alkylated. The cerium organic acid salt may further contain at least one other rare earth metal element in an amount of 25% or less of the total rare earth metal element content including cerium. These compositions are obtained in the form of organic solvent solutions of cerium organic acid salts or mixtures thereof containing more than 200 g/composition. The composition may be added to paints, varnishes or liquid fuels. The method of preparing these cerium organic acid salts or mixtures thereof (in organic or aqueous organic medium) is
Freshly prepared cerium hydroxide (Ce) with an organic acid
It consists of reacting under conditions such that the ratio r of the organic acid salts that produce (OH) ₃ ) is 0.2 to 1.
The reaction is preferably carried out with heating, and the organic medium is preferably a hydrocarbon. After a few hours, some of the water produced by the reaction separates out spontaneously. After the reaction, additional solvents such as glycols, alcohols or alkyl glycols may be added to facilitate separation of water from the reaction medium. The concentration of the solution thus obtained can be adjusted by adding a suitable hydrocarbon. In the embodiment of the above patent, cerium hydroxide (Ce
(OH) ₃ ) is obtained by precipitating cerium nitrate with aqueous ammonia. The precipitate is washed with water until the nitrate ions disappear, and filtered until the water content is 15%. Cerium hydroxide is reacted with 130 g of ordinary quality oleic acid in white spirits at 80°C. 4
After stirring for an hour, add the glycol, remove the separated water, then add the butyl glycol, then add the white spirit to make the final solution. It should be noted that the patentees of the above patents were concerned with cerous salts, not ceric salts. French Patent No. 2482075, US Patent No.
No. 2,382,075 and related cases discussed therein refer to the preparation of easily dispersible aqueous dispersions of cerium compounds.
Hydrated ceria containing NO ₃ ^- , Cl ^- or ClO ₄ ^-
Heating at 200°C to 450°C for 1 to 2 hours yields a material that can be dispersed in an aqueous solution. However, there is no indication that this material can be dispersed in organic media. “Encyclopedia of Chemical Technology” by Kirk Osmer, 2nd edition, Volume 4
On page 850, hydrated ceric oxide, also called hydrous ceric oxide or cerium hydroxide (CeO ₂ x H ₂ O (where x represents a number from 1/2 to 2)), is a ceric salt. It has been shown that addition of sodium or ammonium hydroxide to a solution of hydroxide forms a gelatinous precipitate. Usually called hydrated ceric oxide. 85 ~ when the precipitate dries
A yellow hydrated oxide containing 90% _CeO2 is formed.
Granular ceric hydroxide is prepared by boiling the insoluble cerium salt with concentrated sodium hydroxide, then washing and drying. The composition and structure of these compounds is determined by the method of preparation and is often unclear.
For this reason, it is common practice to express this composition in terms of equivalent _CeO2 . Cerous hydroxide (Ce(OH) ₃ ) is formed as a white or grayish-white gelatinous precipitate when a solution containing cerous ion Ce ³⁺ is made alkaline. If left for a long or short time, a purple surface layer of cellosocerium hydroxide (a mixture of cerous and ceric) will appear. Ceric oxide (CeO ₂ ) is typically made by igniting ceric oxalate or ceric or ceric hydroxide in air. Ceric oxide is insoluble in acids, but dissolution is promoted by adding a small amount of a reducing agent such as iodine ions or hydrogen peroxide. Finally, strong nitric or sulfuric acid reacts when heated. In many applications, hydrated ceric oxide may be replaced by ceric oxide. But unlike cerous hydroxide, which is a traditional type of metal hydroxide similar to Pb(OH) ₂ , Fe(OH) ₃ , etc., ceric hydroxide is actually hydrated cerium dioxide. As mentioned above, it is also called hydrated ceric oxide. The term "cerium dioxide" is therefore understood to include ceric hydroxide, hydrated ceric dioxide and hydrous ceric oxide. These names are different names for essentially the same chemical, cerium dioxide. Stir pure ceric oxide at 60°C in the presence of an aliphatic solvent such as petroleum spirits or an aromatic solvent such as toluene and in the presence of oleic acid, palmitic acid or dodecylbenzenesulfonic acid. When heated at a temperature of ~200℃,
No dispersion occurs. Furthermore, no reaction occurs with other carboxylic acids, alkylsulfonic acids, and alkylarylsulfonic acids. OBJECTS OF THE INVENTION It is an object of the present invention to provide a new type of colloidal cerium dioxide with a high cerium content that can be dispersed in organic liquids, in particular in organic solvents, and to provide a new type of colloidal cerium dioxide having a high cerium content dispersed in organic liquids. The objective is to provide a composition with high The high cerium content dispersions of the present invention are true dispersions as evidenced by transmission electron microscopy. As used herein, the term "dispersed cerium dioxide" means that the ceria particles are colloidal in size;
This therefore indicates that it is present in the form of a colloidal dispersion in an organic liquid, but this does not exclude the presence of ceria in solution form in addition to colloidally dispersed ceria. Transmission electron microscopy of hydrated ceria before treatment of the present invention shows no particles of colloidal size. This conversion of ceria into colloidal size particles takes place during the process of the present invention. DETAILED DESCRIPTION OF THE INVENTION The colloidal cerium dioxide of the present invention comprises (1) 3% to 14% ammonium nitrate in a physically associated state, and (2) an amount of 10 to 60 g per mole of _CeO2 . Obtained from cerium dioxide specifically prepared for use as a feedstock in the process of the invention to contain at least one of water, methanol, acetic acid and mixtures of any two or three thereof. Both (1) and (2) above are essential and must exist. This material is referred to herein as "activated cerium dioxide" or "activated _CeO2 ." Experimental evidence shows that the process of the present invention is characterized by a physisorption-addition reaction (such as salt formation) that introduces an organic acid into crystalline or amorphous cerium dioxide, possibly in its crystal lattice or as an occlusion by chemisorption. It has been established that chemical substitution (as distinct from elimination reactions) is thought to occur. This association is carried out by combining the above activated cerium dioxide with a solubilized organic acid having 10 to 40 carbon atoms and a suitable organic liquid at 60°C.
Heat at a temperature of 200℃ for a sufficient time, usually 1 hour to 24 hours, to turn the aggregate into colloid-sized microcrystals.
large agglomerates of cerium dioxide by associating them with solubilizing acids, then removing the released water, methanol or acetic acid, and leaving aside the salts (unreacted starting material and ammonium nitrate that may be present) that separate on cooling. It is formed by crushing into microcrystals with a diameter of about 50 Å. CeO ₂ -acid associated complexes can be isolated from such colloidal solutions in the form of solid colloidal particles. Examination of the colloidal solution by transmission electron microscopy showed that microcrystals with a particle size of 50 Å were completely dispersed. This complex is stable for some time as long as it is stored in a sealed container. Upon mixing with a suitable organic liquid, a colloidal dispersion is readily obtained. The raw material cerium dioxide may be cerium dioxide, hydrated cerium dioxide, or hydrated cerium dioxide, but the ceria raw material is 3% to 14% by weight.
of ammonium nitrate is essential. It is not sufficient that ammonium nitrate is simply mixed or added to ceria; it is in close physical association with ceria that ammonium nitrate is probably found during the preparation of hydrated ceria as a salt molecule and/or as ammonium ions and nitrate ions. It must be occluded in the structure of the aggregate. The second requirement is that the system contains water, methanol,
The indicated amount of acetic acid or a mixture thereof is present. Cerium dioxide, a suitable raw material for making the products of this invention, is commercially available from Rhone Plan.
It can also be prepared by methods described in patent specifications. For example, as shown in French Patent No. 2,482,075, cerous nitrate or cerous carbonate is treated with an aqueous solution of nitric acid and then treated with NH ₄ OH--H ₂ O ₂ . To achieve the objectives of the present invention, it is not necessary to wash the cerium dioxide recovered, for example by filtration, centrifugation or other separation techniques, but if it is washed, it should be washed sufficiently to remove occluded ammonium nitrate. do not. In this way, the recovered product physically associates 3% to 14% of residual ammonium nitrate and some cerium nitrate. The amount of nitrate can vary depending on the process parameters selected in the manufacture, the amount of remaining mother liquor, and the extent of partial cleaning, if any. When the base used for precipitation is NH ₄ OH,
The ions supported by ceria are NH ₄ ⁺ and NO ₃ ^-
It is easily understood that The wet material as it comes out of the filter has an inconsistent water content. It is noted that if the second requirement is the amount of water present, a wet material that can be used in the present invention requires at least 10 g of water per mole of CeO ₂ . Typically, the amount of water retained in freshly prepared hydrated ceria is between 10% and 20% (0.95-1.91 moles of _H2O per mole of _CeO2 ).
Obviously, a higher water content is acceptable, but
It is troublesome because it has to be removed later in the process. Surprisingly, while methanol can be used in place of water, other lower alcohols such as ethanol are ineffective and cannot be substituted for methanol. Similarly, acetic acid is the only acid that can be substituted for water or methanol. Organic acids used to prepare association complexes cannot be used. Acetic acid, like water and methanol, has the special function of fragmenting the agglomerates in the distillation vessel into colloidal size CeO ₂ by then adding solubilizing acid, a mechanism that is not completely understood. Obviously it has. The amount of water, methanol, acetic acid or a mixture thereof is at least 10 g/mol CeO ₂ to 60 g/mol CeO ₂
It is. Ceria should not be dried for long periods at high temperatures, such as 375°C or higher, where ammonium nitrate will decompose. The reason is that in such cases the NH ₄ NO ₃ content in the ceria produced is lower than the minimum required amount and the ceria obtained is not present in the process of the invention even if water, methanol or acid and free ammonium nitrate are added. However, it is no longer usable. The organic liquid medium may be an inert aliphatic or cycloaliphatic hydrocarbon or a mixture thereof, such as mineral spirits or petroleum spirits or mineral or petroleum ethers, even if they contain aromatic components. good. Examples of these are hexane, heptane, octane,
Examples include nonane, decane, cyclohexane, cyclopentane, and liquid naphthalene. Organic solvents such as benzene, toluene, xylene are also suitable. Chlorinated hydrocarbons such as chlorobenzene and chlorotoluene can also be used in conjunction with aliphatic and cycloaliphatic ethers such as diisopropyl ether and aliphatic and cycloaliphatic ketones. The organic liquid or solvent system is chosen with consideration to the solubilizing organic solvent and heating temperature used and the ultimate use of the colloidal solution or dispersion. In some cases solvent mixtures are preferred. The amount of liquid or solvent obviously determines the final concentration. Solutions containing less than 50% _CeO2 exhibit complete flow. Therefore, it is economical and convenient to prepare solutions that are more concentrated and can be diluted for later use. Therefore, the amount of solvent is not critical. The organic acid forming the physical association complex is an organic acid or a mixture thereof that is soluble in the organic solvent medium used. Natural or synthetic aliphatic carboxylic acids, aliphatic sulfonic acids, aliphatic phosphonic acids, alkylarylsulfonic acids and alkylarylphosphonic acids having 10 to 40 carbon atoms can be used. Examples of these include tall oil fatty acids, oleic acid, stearic acid, isostearic acid, lauric acid, 2-ethylhexanoic acid, naphthenic acid, hexanoic acid, toluenesulfonic acid, toluenephosphonic acid, laurylsulfonic acid, laurylphosphonic acid, Includes palmitylsulfonic acid and palmitylphosphonic acid. The type of solubilizing organic acid used often determines the maximum dispersion of CeO ₂ . Alkylaromatic sulfonic acids tend to give products with higher Ce concentrations. The organic acid contains at least 20% of CeO ₂ per mole of CeO ₂ as long as the physical association complex of CeO 2 -acid contains a 4:1 ratio of CeO ₂ and organic acid as evidenced by the isolated solid composition. Use an amount of 0.25 mol. Although the amount of acid used can be reduced, the dispersion of ceria may become incomplete or the resulting dispersion is relatively unstable and tends to precipitate CeO ₂ . Even more than 0.25 moles of organic acid can be used, but it is not necessary. The presence of water, methanol, acetic acid, or a mixture thereof is essential during the cooking phase, but their role remains unexplained. It can at least be said that they serve to eliminate nitrate ions in such a way that the decomposition of CeO ₂ agglomerates into colloidal-sized particles occurs. The highly active surface of the microcrystals adsorbs acids, making the microcrystals organically dispersible. If any of the essential activating volatile components, such as water, methanol or acetic acid, are removed from the system before the desired step has proceeded, the reaction will not proceed at all or will be incomplete. Commercial grades of hydrated ceria contain other rare earth elements as impurities. In some cases, the presence of such impurities is desirable as advantageous synergistic effects may be exerted. In the method of the present invention, approximately 10
Mixtures of ceria containing up to % of other rare earth elements can also be used. The entire heating takes from less than 1 hour to 24 hours while heating and stirring at a temperature of 60°C to 200°C. The raw material cerium dioxide is preheated as an aqueous slurry or mixed with organic liquids such as petroleum spirits at temperatures between 60°C and 200°C for several hours and then used to form physical association complexes such as oleic acid. Addition of organic acids significantly increases the rate of solubilization. Transmission electron microscopy examination of the heated material reveals no reduction in the size of the ceria particles, hence the weakening of the ammonium nitrate and/or NH ₄ ⁺ and NO ₃ ^- ion bridges upon heating the microcrystals. However, it seems that it will not be destroyed. When treated under mild reaction conditions, decomposition of ceria to colloidal size is achieved by adsorption of organic acids such as oleic acid onto ceria particles, which also makes colloidal particles dispersible in non-aqueous organic liquids or solvents. It seems that they are doing so. The colloidal dispersion produced by the above method therefore contains the solubilized acid as free acid but not in ionized form. Therefore, the cerium dioxide products described herein are not considered cerium soaps. This is because cerium soap is essentially an ionized aliphatic cerium salt. The colloidal potassium dioxide dispersions in organic liquids of the present invention can be used as drying agents in paint and varnish formulations. [Examples] The present invention will be described in more detail below with reference to preferred embodiments of the present invention. Example 1 77.5% CeO ₂ (0.248 mol), 15.5% water in a three-necked reaction flask equipped with a stirrer, thermometer, and condenser.
and ammonium nitrate 7.0% (as occlusion)
55g of active _CeO2 containing 17.6g of oleic acid (0.062
mol), and AMSCO® as solvent
(Aliphatic hydrocarbon) 35.0g was charged. The mixture was stirred and gradually heated to 90°C, and this temperature was maintained with stirring for 2 hours. The reaction started at 55°C to 60°C as indicated by the appearance of water droplets. During this time
The solid suspension of CeO ₂ turns into a brown colored colloidal solution containing visible water. Hexane was added and the system was dried azeotropically, collecting 8.5 g of water. After removal of most of the entrainer, a dark brown colloidal solution was filtered. _CeO2 content was 44%. As a control, pure cerium dioxide (99.5%
CeO ₂ ) in AMSCO solvent in the presence of oleic acid without or with water at 90°C to 140°C.
Although it was stirred for several days, it did not disperse. Example 2-21 The following ceria preparation was made following the same procedure as in Example 1 using the same active CeO ₂ as in Example 1, the same molar ratios of CeO ₂ to acid and solvent as in Example 1, and using the acids and solvents shown in the table. Ivy. Complete dispersion of ceria was achieved in all cases.

[Table] Acid

[Table] Example 22 CeO ₂ 80.17%, NH ₄ NO ₃ 2.9% and H ₂ O 16.9%
Contains 3.1 g per mole of CeO ₂ and dried under vacuum at 95°C.
An attempt was made to disperse active CeO ₂ with a residual water content of 100 ml according to the same procedure as in Example 1 using the same solvent and oleic acid as in Example 1, but no reaction or dispersion occurred. 12 g of methanol per mole of CeO ₂ is then added and the mixture is heated to 76° C. as in Example 1.
Cooked at 113°C for 4 hours. This time a complete dispersion occurred. Removal of methanol and water resulted in a colloidal solution or dispersion of AMSCO containing 45% ceria. Examples 23 and 24, Example 25 (Comparative Example) Active CeO ₂ having the composition shown in Example 22 was dried in an oven at 100°C for 16 hours and had a residual moisture content of 6.6 g per mole of CeO ₂ at 0.25 g per mole of CeO ₂ . Moles of oleic acid were heated with or without water under the conditions listed in the table below.

Table: The dispersion of Examples 23 and 24 was complete, but in Example 25 it was incomplete. In example 25, the distribution is not perfect, so
6.6 g of water per mole of CeO ₂ is borderline. Example 26 (comparative example), Example 27 and Example 28 (comparative example) Activated CeO 2 containing 75% CeO ₂ , 6.5% NH ₄ NO ₃ and 16.9% H _{2 O} was oven dried at 175° C. for 72 hours.
Oleic acid as an organic acid under the conditions shown in Example 26
0.25 mol/mol _CeO2 was used. The dehydrated ceria was then cooked using additional water (Example 27) or ethanol (Example 28) in the amounts indicated in the table for the times and temperatures indicated.

[Table] Only Example 27 resulted in a complete colloidal solution or dispersion as expected. Example 26 contains no water, Example 28 contains ethanol but neither water nor ethanol,
In either case, ceria dispersion did not occur clearly. Examples 29-30 The active _CeO2 of Examples 26-28 was azeotropically dried with toluene. Instead of water, methanol (Example 29) or acetic acid (Example 30) was added together with oleic acid and the dry powder was dispersed under the conditions indicated in the table.

[Table] Enoic acid
30 Tol Oley Acetic Acid 18.0 67〓102 Overnight Enoic Acid
Example 31 (Comparative Example) Activated CeO ₂ from Example 1 was heated at 350° C. for 24 hours. Mix ceria with AMSCO, oleic acid and water,
Cooked in the same manner as in Example 27. No dispersion was observed even after adding methanol or acetic acid to the reaction mixture after several days of heating. Example 32 A 20 g sample of the colloidal solution prepared in Example 1 was slowly poured into 100 g of acetone at room temperature. After stirring for several hours at room temperature, the solid is separated and washed several times with acetone. Analysis of the vacuum-dried solid showed that it had the following composition. Ce 57.9% C 21.11% H ₂ 3.48% O ₂ 16.51% (difference) Empirical formula: Ce ₄ C ₁₈ H ₃₈ O ₁₀ Chemical formula (CeO ₂ ) ₄ (oleic acid) The obtained solid is an inert aliphatic or Soluble in cycloaliphatic hydrocarbons, ketones and ethers, and chlorinated aromatic hydrocarbon solvents. A transmission electron micrograph of this material is shown in FIG. Acid is strongly adsorbed on the surface of ceria, but simple extraction with methanol yields free acid in an amount that is approximately 10% of the theoretical amount of adsorption. This suggests that oleic acid is adsorbed on the surface of ceria particles generated during the dispersion process. Support for this proposal is obtained by considering the infrared spectra for the starting materials and the final product. The carbonyl stretching vibration of free oleic acid is 1708
cm ^-1 , which is exactly in the range expected for a carbonyl group attached to an aliphatic chain. There is no evidence of the presence of free oleic acid in the IR spectra of the kneaded solid or the initial dispersion. However, a strong (but broad) band is observed at 1510 cm ^-1 (independent of solvent), a feature attributed to the perturbed carbonyl stretching mode of the adsorbed oleic acid. Example 33 Commercial grade hydrated ceria containing 8.36% ammonium nitrate and 21.34% total water content was stirred in AMSCO with oleic acid at 90°C as in Example 1.
Dispersion was achieved in 17 hours. A sample of hydrated ceria (62.15g) of the same brand was mixed with 14.4g of water and heated at 90°C to 100°C for 5 hours. Excess water was removed by filtration and oleic acid
Add 17.59g and 34.95g AMSCO and mix
Heated at 90°C. Dispersion was achieved in 4 hours instead of 17 hours. 100g of the hydrated ceria sample used in Example 33
When heated at 400℃ for 16 hours, cerium dioxide
71.8 g of dry powder was obtained containing 70.3 g and 1.5 g of nitrate. When 43.9 g of this drying material was mixed with AMSCO and oleic acid and heated at 90° C. with or without water, no dispersion occurred even after 24 hours. Example 34 The active CeO ₂ sample used in Example 4 is
It was heated in AMSCO at 90° C. for 6 hours and then only oleic acid was added instead of the mixture of lauric acid and oleic acid of Example 4. Dispersion required a total of 1.5 hours after acid addition.

[Brief explanation of the drawing]

FIG. 1 is a transmission electron micrograph showing the shape of typical cerium dioxide crystal grains before treatment according to the method of the present invention, and FIG. 2 is a transmission electron micrograph showing the shape of particles after processing.

Claims (1)

[Claims] 1 (a) occluded ammonium nitrate in an amount of 3% to 14% by weight relative to cerium dioxide;
cerium dioxide selected from water, methanol, acetic acid, and mixtures thereof, containing a substance in an amount sufficient to react with the organic acid b at 10 g or more per mole of cerium dioxide; (b) carbon number 10; ~40 organic acids, and (c) an organic liquid selected from the group consisting of aliphatic and aromatic hydrocarbons, aliphatic and cycloaliphatic ethers, and aliphatic and cycloaliphatic ketones at a temperature of 60°C to 200°C. It is characterized by heating to form a colloidal dispersion in which cerium dioxide and associated organic acid are dispersed in an organic liquid, removing water, methanol or acetic acid generated during heating, and separating insoluble solid particles. A method for producing a dispersion of selim dioxide in an inert organic liquid. 2. The method according to claim 1, characterized in that water is used. 3. The method according to claim 1, characterized in that methanol is used. 4. Process according to claim 1, characterized in that a mixture of water and methanol is used. 5. The method according to claim 1, characterized in that acetic acid is used. 6. Process according to claim 1, characterized in that a mixture of water and acetic acid is used. 7. Process according to claim 1, characterized in that a mixture of water, methanol and acetic acid is used. 8. The method according to claim 1, characterized in that the organic liquid is an aliphatic hydrocarbon. 9. The method according to claim 1, characterized in that the organic liquid is an aromatic hydrocarbon. 10. The method according to claim 1, characterized in that the organic liquid is an aliphatic or cycloaliphatic ether. 11. The method according to claim 1, characterized in that the organic liquid is an aliphatic or cycloaliphatic ketone. 12. The method according to claim 1, wherein the organic acid is oleic acid. 13. The method according to claim 1, wherein the organic acid is lauric acid. 14 The organic acid is an alkyl sulfonic acid or an alkyl aromatic sulfonic acid,
A method according to claim 1. 15. The method according to claim 1, wherein the organic acid is isostearic acid. 16. The method according to claim 1, wherein the organic acid is tallow fatty acid. 17. The method according to claim 1, wherein the organic acid is a linseed oil fatty acid. 18. The method according to claim 1, wherein the organic acid is benzenesulfonic acid. 19. Process according to claim 1, characterized in that the amount of water, methanol or acetic acid is between 10 and 60 g per mole of cerium dioxide. 20. Claim 1, characterized in that a cerium dioxide composition containing ammonium nitrate is heated at a temperature of 60°C to 200°C in the presence of water or an organic liquid, and an organic acid is added to the resulting mixture. the method of. 21. Process according to claim 20, characterized in that the cerium dioxide is in the form of an aqueous slurry. 22. Process according to claim 20, characterized in that the cerium dioxide is in the form of a slurry with an organic liquid. 23. The method according to claim 22, characterized in that the organic liquid is an aliphatic hydrocarbon. 24. The method according to claim 22, characterized in that the organic acid is oleic acid.