MXPA00002451A - Composition based on an organic sol of tetravalent metal oxide and an organic alkaline-earth compound - Google Patents

Abstract

The invention concerns a composition comprising an organic sol of particles of at least one tetravalent metal oxide, and at least an organic compound of at least one alkaline-earth. The composition may further contain at least an organic compound of at least an alkaline. The tetravalent metal is more particularly cerium. The invention also concerns the use of said composition as additive of hydrocarbon compounds.

Description

BASED COMPOSITION. IN A SUN. ORGANIC OF OXIDE OF. TETRAVALENT METAL AND AN ORGANIC COMPOUND OF METAL ALKALINE TERREO The present invention discloses a composition based on at least one organic compound of at least one alkali metal tea and of a sol to the rtexL? Soxoxid of at least one tetravalent metal. . The subject of the present invention is also a process for obtaining these compositions, as well as their use. It is known that during the combustion of diesel in the diesel engine, carbon products have the tendency to form soot, which is reputed to be harmful both to the environment and to health. They have long been techniques for reducing the emission of these carbonaceous particles, which will be designated in the following description under the expression of ?? _ holl_í_n '' ^ E-sta irare ^ -tig ci-ón . e_s con.com_Lt-aj_Lt.e with. The need not to increase the emission of carbon monoxide and of reputed toxic and mutagenic gases, such as the oxides of r it _ _ óg M. M. M. M. M., and many solutions have been proposed to reduce these carbon emissions.

One goes every day towards the adaptation in the exhaust circuits of a filter capable of stopping the whole, or a very large proportion (at least 80% by mass) of the carbonaceous particles generated by IB. change xie _l_o_s various fuels. This technique is, however, limited by the storage capacity of the filter, which must either be emptied, or it is to burn the soot contained .. JLs ± a operation. Regeneration call is extremely expensive to foresee and put into work. One of the most commonly proposed solutions is the combustion of this soot, combustion caused by intermittent fogging either by electric heating, or by the use of an ignition fuel f .. This technique presents no amount or number. -s inconveniences, of which the minor is not the risk of thermal shock leading to a fracture or cracking of the ceramic filter, or a melting of the filter m_etál-i_o._ A solution that would be, satisfactory _consisf_e in introducing in the soot catalysts that allow a frequent self-inflammation of the soot collected in the filter. For this, it is necessary that this soot presents a peratmra of self-inflammation sufficiently low to be frequently reached during a normal running of the engine. One realizes that clouds in general, and cerium in particular, could be a good element to reduce the fempernf ra of self-inflammation of soot. However, the need is felt to have a product that, after introduction into a gas oil, after combustion, gives a good self-ignition of the soot at a still lower temperature. With this object, the composition of the invention is characterized by comprising an organic sol of at least one oxidized at least one tetravalent uefal and at least one organic compound of at least one alkaline-thermal metal. ex. In the sense of the invention, one means to designate by sol, an organic colloidal suspension of particles of at least one oxide of at least one tetravalent metal. The tetravalent metal can be selected from rare earths that can form tetravalent metal oxides. Jar rare earth is understood the elements of the group constituted by the yttrium and the elements of the periodic classification of atomic number between 57 and 71. The periodic classification of the elements to which ZISLC is reference is published in the Supplement to the Chemical Bulletin of France No_ 1 January-1566). For this reason the cerium, the praseodymium, and the terbium can be cited. In the particular case of rare earth mixtures, it is preferable that the cerium be present. The tetravalent material is more resistant to the cerium. The alkaline earth metal can be ex selected from magnesium, calcium, strontium, or barium. More particularly, the alkaline-ferrine is calcium or strontium. According to a preferred variant of the invention, the composition comprises an organic sol of cerium oxide particles and aJ. minor one ccmpues ± c org nice. of strontium _ The composition of the. In addition, the invention may comprise at least one organic compound of at least one alkali metal. The alkaline metal will then be between the sodia? potassium or cesium. Also agree within the framework of the present invention are compositions comprising one or more organic compound (s) of one or more alkaline earth metals, and, if appropriate, one or more organic compound (s) of one or more alkali metals. E7L organic metal compound alcal_ine-1erree or eta. alkaline is an organometallic complex of the type described in the WO patent application 96/34074 whose teachings related to this are incorporated in the pre_sent_ can be very particularly the complex defined in this application WO 96/34074 by the formula M (R) mnL, in which: 0 M is the goal, the .ca. ljj? ot XxeO and even alkaline .meta, QR is the residue of an organic compound of formula JBJ3 in which H represents an active hydrogen atom reactive with e. metal M and bound to either a heteroatom selected from O, S and N in the organic group R, or to a carbon atom. This Jeteroatomo to this carbon atom is located in the organic group R, close to a group electro-attractant, for example a hetero-atom in a group consisting of or containing O, S or N, or an aromatic ring, for example phenyl, 0 n is a number indicating the number of organic donor molecules (Lewis basea) which forms dative junctions with the metal cation in the complex, usually up to 5 in number., more jointly an integer from 1 to 4, and DL is one or several electro-donor ligands (bases of Lewis). R can understand one or several groups works 1 is able to act as organic ligand electro-donor. All of the teachings of WO 967341) 74 relating to the aforementioned complex of formula are incorporated herein by reference. According to a particular embodiment, the organic sol citadp formerly contains: Q particles of at least one oxide of at least one tetraval metal nt ^ D an amphiphilic acid system, and D a diluent *. and is further characterized by the fact that the particles have a d9a at most equal to 20 nanometers, and exhibits at least one of the following characteristics: the oxide particles. { s of tetravalent (as the crystallites are agglomerated, whose dS £) measured by photometric counting (electron microscopy by high resolution transmission), is at most equal to 5 nanometers, 90% by mass of the agglomerates comprises from 1 to 5, preferably 1 ß. 3 cria, t "a., 1 ifea., • the amphiphilic acid system comprising at least one acid of 10 a. 5D Carbonaceae, with at least one branch in alpha, beta, gamma or delta of the atom carrying the acid hydride. The tetravalent metal oxide particles mentioned above are advantageously cerium dioxide. In the following of the exhibition, what has been described for the particular case of cerium, can also be applied to Xas ot to jaazcí of ti errras previously mentioned (in which the cerium is always preaenfe.) _ The characteristics of the sun of This particular mode of realization is going to be in the lower range. In the present description, -characteristics of granulometry frequently refer to notations of type d? where n is a number from 1 to 99. This notation represents the particle size such that n% in peae of Xas particles has a size smaller than or equal to the size. For example, a d90 of 5 nanometers means that SO% by weight of the particles have a size less than or equal to 5 nanometers.

These condition more apramian ± ea., And J_a rnanpra to respond to. they are exposed below. Advantageously, at least 50% by mass of the agglomerates are monocrystalline, that is to say, they are constituted only of a single chrysotile (at least they seem to be constituted only of a single crystallite, when the sun is examined by METHR (High Resolution Transmission Electron Microscopy) - »In addition to playing the technique and Xas hydrolysis conditions, it can be expected that 80%, preferably 90% by weight of the criatalitoa S BB ?. size in the range of 2 to 5 nanometers Advantageousness - the relationship between the amphiphilic acid and the metallic elements of the sun is at most equal to 0.5 to 0.50. 0.4, ..of ..preference to the most equal to 0.3, here the molar relationship must be established in the acceptance of a relationship, functional molar, that is to say that the number of moJ.es multiplied by the number of useful acid functions is counted as moles of ampholyllic acid. It is desirable that. in the sun, the. relationship between .la. the proportion of cerium (III) and the proportion of cerium (IV) is as small as possible, in the lower 1.5%, advantageously to the most equal to 1%, preferably to 0.5%. Sale ^ je = amente., The sun pxesejits. a concentration such that the proportion of cerium dioxide contained is between 10 and 60%, preferably 30 to 50% by mass. Thus, the ..ce ie,. It is essentially. the form of a material, metal oxide agglomerate, optionally hydrated dioxide, the oxide material (s) becomes fat-soluble by means of an amphiphilic organic acid. In the sun, the dirt may be accompanied by impurities. Within the framework of the present invention, the purity of the cerium is not critical. L.as -aoles of this type, as well as their modes of preparation so.n.known by the expert in the technical ..

However, as an example of preparation of a cerium-based sol, the following preparation procedure can be described. This process comprises the following steps, which consist of: a) submitting an aqueous phase containing cerium to a hydrolysis operation, to precipitate a cerium dioxide, b) ... putting in contact, simultaneously or consecutively , a suspension of cerium dioxide resulting from step (a) with an organic phase comprising an organic acid, and preferably a compound or an organic mixture that performs the solvent role, and then c) recovering the organic phase - phase constitutes a sun. The procedure of preparation of the sun will be. developed now more in detail. yentajosamente., You can proceed between JLa stage (a) and stage (b), to a separation of the solid particles of the mother liquor, possibly to a drying preferably by atomization, and then to resuspend the particular rólidar in watery zs, which will then be subjected to step (b). The resuspension is conducted so that the content of cerium dioxide in the aqueous phase is between 100 and 100%. gjl-. According to an advantageous application of the present invention, the drying of the steps (a and b) is advantageously carried out by atomization, that is by spraying the mixture of the rolers in a hot atmosphere (spray drying). The atomization can be carried out by means of any sprayer known for example by a spray nozzle of the spray pineapple type or another. It is also possible to use so-called turbine atomizers. On the various susceptible spraying techniques applied in the present procedure, one could refer in particular to the MASTERS base work entitled "SPRAX-DRYI G" (second edition, 1976. George Godwin editions - London). It will be noted that the atomization-drying operation can also be applied by means of an "instantaneous" reactor, for example of the punched-out type by the Applicant and described particularly in the French patent applications numbered 2.251 3.26 ,, _2 419 754 .and 2 431 321. In this case, the treatment gases and hot gases) are animated by a helical movement, and diffuse into a well-vortex. The mixture to be dried is injected according to a path that is confused with the axis of symmetry of the helical paths of the gases. It allows you to perfectly transfer the amount of movement of JLos. Gases to the mixture to be treated. The gas thus ensures a double function: on the one hand the pulverization, that is to say the transformation into fine droplets, of the initial mixture, and on the other hand the drying of the obtained droplets. On the other hand. the extremely short residence time (generally less than about 1/10 of a second) of the particles in the present reactor, among others, limit the unlikely risks of overheating as a result of prolonged contact with hot gases. It should be noted here that this atomization treatment allows to improve sinificativamente the fitness of a role termo __? Idroli_zado to "baja". Temper ture to form, stable suns, and even when the temperature of the gases is at least equal to 200 ° C, of preferably between 200 and 7300 ° C, obtain results similar to those obtained by a thermo-hydrolytic to "alia" temperature (.150 ° C), and thus soles according to the present invention that are optimal. The temperature of the relapse atmosphere can vary in wide limits,. and it depends particularly on the average dwell time that is desired or that can be imposed on the atomized product once in the atmosphere. In a general way. Xas candieloner drying (temperature and / or residence time) are determined in a classical way to obtain a total or almost total elimination of the residual water contained in the product, that is to say, globally, it is enough to obtain a constant weight for the latter.

The solid particles will then be re-suspended in the aqueous phase. As cerium compounds soluble in water, mention may be made in particular of cerium (IV) salts, such as nitrates, or ammoniacal nitrates, for example, which are particularly suitable here. . Preferentially, use of nitrate cerica. The cerium (IV) salt solution may contain cerium without a drawback in the cerium state, but it is desirable that it contain at least 5 __ of celexa I1Y) _. lina The aqueous oxide of ceric nitrate can for example be obtained by reaction of nitric acid on a hydrated ceric oxide, prepared in a conventional manner by reaction of a solution of carious salt, for example, cerium carbonate, and a solution of ammonia in presence of oxygenated water. It is also possible, preferably, to use a solution of ceric nitrate obtained according to the method of electrolytic exudation of a solution of nitrate, as described in document FR 2 570 087, and which constitutes here a primary selection material. It will be noted here that the aqueous solution of cerium (IV) ralea may have a certain initial free acidity, for example a normality varying between 0.1 and 4 N. According to the invention, it is equally possible to apply an initial solution of salts of cerium (IV) that presents. effectively. a certain free acidity as mentioned above, that a solution that would have been neutralized in a less-than-stimulated manner by addition of a base, such as for example an ammonia solution, and even alkali metal nidroxides, particularly sodium, or potassium, but preferably a solution of ammonia, to limit this acidity. You can then, in the latter case, define XB XBXB. click a neutralization precess (r) of the initial solution of cerium by the equation riguie e: r = n3 - n2 ni in which neither represents the total number of moles of Ce (IV) present in the final solution of J neutralization ^ n2 represents the total number of moles of OH- ions actually needed to neutralize the initial free acidity contributed by the aqueous solution of cerium salt ÍIV), and n3 reprerenta yi n meritj. of moles of OH ions "contributed by the addition of the base When the applied" neutralization "variant is used, in all cases a quantity of base that ... should be imperatively less than. that it would be necessary to obtain the precipitation to the end of the carbon dioxide spectrum. (r) 4. In practice, one is thus limited to neutralization ratios not exceeding JL, and preferably not exceeding 0.5, the next operation consists of making a hydrolysis to precipitate a cerium dioxide, the precipitation of the cerium dioxide is effected by a thermal treatment, Called thermohydrolysis at a temperature at a temperature of 40 ° C, the thermal hydrolysis can be between 80 ° C and the critical temperature of the reaction medium, in particular at 80 and 350 ° C, preferably between 90 and 200 ° C. ° C. ^ This treatment can be conducted, according to the conditions of selected temperatures, either under normal atmospheric pressure, either under pressure such as, for example, the saturation vapor pressure corresponding to. Iza temperature of the thermal treatment. When, as is preferred, the treatment temperature is selected above the reflux temperature (under ordinary pressure of the reaction mixture (ie, generally above 10 ° C) for example selected from 120 to 00 ° C, more often between 150 and 350 ° C, the operation is then conducted in a closed vessel, which is in particular a closed reactor, more commonly called an autoclave.The aqueous mixture containing the species previously mentioned in this vessel is introduced. The necessary reflection does not result from the heating of the reaction medium alone (autogenous pressure)., and in an aqueous medium, it can thus be specified, by way of illustration, that the prerión in the cerrasTo reactor varies between a value greater than L 0X9 kg / cm2 (1 bar ^ 105 Pa) and 200 bar (20 JX ID7 Pa), preferably between 5.095 kg / cm2 (5 _bar, 5 _x105 Pa) and 152.85 kg / cm2 (1.5 x 175 Pa). Of course it is equally possible to exercise an external prerogative, which then adds to the consecutive one to warming. The heating can be carried out either under an air atmosphere, either under an inert gas atmosphere, preferably with a non-critical atmosphere. The duration of the treatment is not critical, it can thus vary in large limits, for example between 1 and 48 hours, preferably between 2 and 24 hours. Likewise, the rise in temperature is effected at a speed that is not critical, and the set reaction temperature can be reached by heating the medium, for example, 30 minutes and 4 hours, these values are given as a purely indicative indication. In the thermohydrolysis step [step (a)], a solid precipitate is recovered, which can be separated from its environment by any classical solid separation technique -XXquide such as e.g. employs elutriation, filtration, decantation, runoff or centrifugation. It will be noted that it is possible to repeat one or several times, identically or otherwise, a heating step (thermohydrolyzing) / precipitation as defined above, then applying for example thermal treatment cycles. , it can be used as a starting solution for thermolhydrification soXncXones cerium (IV), in general nitrate, which respond to the following characteristics: The characteristic of step 8b) of the process of the invention is to obtain an organic sol, an expression which designates Xa drperrion? EX cerium dioxide, optionally impure, in an organic medium, by transferring the cerium dioxide to the organic phase *, from an aqueous phase constituted by the cpmpuesfo. is found under colloidal Xa Xaxzaa in a watery sun. The colloidal dispersion of cerium dioxide in an aqueous medium constituting the primary base material of stage Xb) is designated by aqueous sol. In order to conduct the process of the invention in a manner which is reasonable, it is desirable that the starting aqueous sol satisfy the following requirements: the proportion of metal (s) below the colloidal oxide (s) (s) must to be very high, advantageously .9.0%, of preference higher than and equal to 95%, and as a rule as high as possible, the concentration of the aqueous sol in colloidal oxide must be. Sufficient sex, and preferably be between 0.1 and .3.moles / J-ifro, * The aqueous sol must have good properties of thermal stability, and not flocculate at the temperature of. reaction that is greater than 60 ° C, and varies more frequently between 30 °. and JLa . boiling. X variable according to pressure). The organic liquid medium used in step (b) of the process may be an aliphatic hydrocarbon, inert cycloaliphatic, or mixed, such as, for example, mineral or petroleum essences, mineral or petroleum ethers which may also contain aromatic compounds. Mention may be made, by way of indication, of hexane, heptane, octane, nonane, decane, cyclohexane, cyclopentane, cycloheptane and liquid naphthalenes. The aromatic solvents such as benzene, the. toluene, ethylbenzene and xylene also agree, as well as the oil cuts of the ISOPAR or SOLVESSO type (trademarks registered by EXXON), particularly SOLVESSO 100, which essentially contains a mixture of methyl ethyl and trimethylbeigene, and SOLVESSO 150, which contains a mixture of alkylbenzene in particular dimethylethylbenzene and tetramethylbenzene. They may also be chlorinated hydrocarbons such as chloro- or dichlorobenzene, chlorotoluene, as well as aliphatic and cycloaliphatic ethers, such as diisopropyl ether, dibutyl ether, and ketone and cycloaliphatic such as methyl isobutyl ketone; diisobutyketone, the oxide of mesity. The esters can be considered, but they have the disadvantage of coxxex the hydrolyzed rer. Mention may be made, as esters which can be used, of those resulting from the acids mentioned in Xa of the present application with alcohols having from 1 to 8 carbon atoms, and particularly in the case of alcohols, such as isopropanol. The organic liquid or the maximum amount of solvent will be selected, taking into account the organic acid solubilizers used. Xa temperature of heating and the final application of the solution or colloidal dispersion. In certain cases, it is preferable to use a mixture of solvents. The amount of liquid or solvents obviously determines the final concentration. It is more economical and more convenient to prepare more concentrated dispersions which could be diluted later, during use. It is for this reason that the amount of solvent is not critical. It may be advantageous to add an agent in the organic phase. promoter whose function. as transfer of the colloids from the aqueous phase to the organic phase * and improve the stability of the organic sols obtained. As agents promoters, SB can use the compounds with alcohol functionality, and very particularly linear or branched aliphatic alcohols having from ß to 12 carbon atoms. As a specific jemplor, re can i. ta r 2-ethyl hexanql, decanol, dodecanol, or their mixtures. The proportion of the agent's agent in the company -organic, not er_ c_ _ _ _ icatica, and may vary widely. However, a proportion between 2 and 15% in. weight usually agrees well. If the field of usable acids is vast, the number totai. The carbon number in the molecule to obtain a good solution is a little more urgent. The total number (average if the acid uses or is a mixture) of the carbons of the acids is sold suitably above ß, preferably to 10- JEs equally. It is desirable that it be less than about 60. If eXeve concentrations are desired in CBXXO-, or an equivalent it is desirable to select acids as short as possible. These acids can be linear or branched.

It is preferable, however, that the branches be either carboxylic, or not numerous, and sustained by difunctional carbons, or carboxylic acids which can be used for the present invention can be n-thrilic, aliphatic or arylaliphatic acids. They can carry other functions, on the condition that these functors are BS ta X is in the means where it is desired to use the cerium compounds according to the present invention. So that the sun remains usable at a low temperature, below the ambient, even below. 0 ° C, is it preferable that the melting point of the acid or the acid mixture is X? Rarely at 50 ° C, advantageously at room temperature, preferably at 0 ° C.

Thus it is easily possible to use carboxylic acid Xos whose carbon chain carries ketonic functions, such as the pyruvic acids subituted in alpha of the. Ketone function. This may also be the case of the alpha-ha halogen carboxylic acids and the alpha-hydroxy aarboxylic acids. The chain attached to the CaxbojsíJLice group can lead to unsaturation. However, in general, it tends to avoid numerous, double bonds, since cerium catalyzes the crosslinking of double bonds in Xaces. The chain can be interrupted by ether or ester functions, provided that the lipophilicity of the chain is not altered too much. Carrier ^ of the carboxylic group. Thus, they can apply carbon, aliphatic or aliphatic, aliphatic sulphonic acids, aliphatic phosphonic acids, alkylaryluronic acid, and alkylarylphosphonic acids having about 10 to about 40 carbon atoms, which are reactivated or synthetic. They can be used alone or as a mixture between them. By way of example, there can be mentioned the fatty acids of resin oil * of coconut oil * of soybean, sebum, of linseed oil, olaic acid, linoleic acid, stearic acid and its isomers, pelargonic acid , the acid. capricum, .lamaric acid, myristic acid, dodecylbenzenesulfonic acid, 2-efJ.ll_exanoic acid,. Naphthenic acid, hexoic acid, toluenesulfonic acid, toluene phosphonic acid, lauryl sulphonic acid, laurylphesophonic acid, palmitylsulphonic acid, and palmitic acid phosphonic acid. Preferably, re uses oleic acid or alkylarylsulfonic acid. The amount of applied amphiphilic organic acid, expressed in the number of moles of acid per mole of oxide can vary widely, between 1/10 and 1. mol of cerium dioxide. The upper limit does not present a critical chaxcicex, but nexae needs to be put into the more acidic jar. Preferentially, the organic acid is applied at a ratio of 1/5 to 4/5 mol per mol dß-cerium dioxide. In the organic phase, the proportion enters the organic solvent and the organic acid is not critical. The weight ratio between the organic solvent and the organic acid is not critical. The weight ratio between the oxalic solvent and the Oxgasic acid selected from preference-between-0.- 3- and Z-Q_- The order of introduction of the different reagents is indifferent. The simultaneous mixing of the colloidal aqueous dispersion (s), the organic acid, the organic solvent and, optionally, the promoter agent can be carried out. You can also Jiacer the premix of organic acid,? the organic solvent and eventually the promoter agent that make up the organic phase. The temperature of the reaction medium is preferably selected in a range of from 0 to 150 ° C. In certain cases, because of the volatility of the organic solvent, it is desirable to condense its vapors by cooling to a temperature below the point of boiling. Advantageously, work is carried out at a temperature between 60 and 120 ° C, preferably between 90 and 110 ° C. The reaction mixture is kept under stirring for the entire duration of the heating, which may be less than one oxa to one approximately * day of preference between 2 hours and a half day. At the end of the aforementioned heating time, heating is interrupted. It is noted the presence of two fares an organic fare which contains in dispersion the metal oxide-organic acid complex, and a residual aqueous phase. The organic Xa XasB and J The aqueous phase is then separated according to the classical separation techniques: decantation, centrifugation, etc. According to the present invention * colloidal organic dispersions of metal oxide (s) are obtained whose size of the colloids can be very variable, and can be controlled by playing on certain parameters * particularly the diameter of the aqueous colloidal dispersions of paxtXda in Xa stage ib), which depends on the respect of the thermohydrolysis conditions in stage (a). For certain applications, it is possible to use the reaction mixture, which is sometimes desirable to remove the water, which may represent 1 to 3% by weight of the organic phase. For this purpose, means well known to the person skilled in the art are applied, for example a pass over a drying agent (included in a hydrophobic membrane filter) or the addition of a third solvent inert to the cerium dioxide, which has a boiling point of pxefer in Xa lower than Xf) O ° C, and which forms an azeotrope with the water, and then a distillation of the obtained azeotrope. As the third solvent suitable for the invention, mention may be made of aliphatic hydrocarbons, such as hexane, heptane, aromatic cycloaliphatic hydrocarbons, or X-aXhoxys such as, for example, ethanol, ethylene glycol, diethylene glycol, etc. It is preferable, particularly for Xas applications as a gas oil adjuvant that the water content be at least equal to 1%, advantageously at 1 OD0 ppm, preferably at 100 ppm. ^ Now we are going to examine the -S-Ls-topic -of amphiphilic acids? Ps. As already mentioned, the amphiphilic acid system comprises at least one acid of 10 to 50 carbon atoms, which presents to the enns an alpha, beta, gamma or delta branching of the hydrogen atom bearing atom. Advantageously, the Amphiphilic acid comprises at least one acid of IX to 25 carbon atom. The preferred domain is from 15 to 25 carbon atoms for X.sub.oxes of the amino acid. For best results, especially when the length of Xa cadBna er small Linteri or 14 carbon atoms), when the branching is unique and above when located in gamma posXcXóxL or delta of the atom carrying the hydrogen hydrogen, is very It is desirable that this branch be at least two carbon atoms, advantageously three. To clarify the nomenclature of X positions, examples of the acid phosphate of di (2-ethylhexyl) and 2-ethyl octanoic acid will be found below.

It is preferred that the delivery X ineaX larger s.Ba of at least 6, preferably 8 carbon atoms. It is advantageous if the pKa of at least one of the acids is at least equal to 5, preferably 4.5. It is also advantageous that Xa or the side chain (s) of the branched acids comprise at least two atoms, preferably three carbon atoms. ps preferable_, particularly when XL? s acids- are. Acids Ca rbox i. liquor the system, of amphiphilic acid is a mixture of acids. In this case, the conditions on the branching must play on the half, half, advantageously two thirds, preferably four fifths of a mole of the acids constituting the amphiphilic acid system. Among the acids that give us very much sulfur, we can mention phosphorus-containing acids, such as phosphoric acids, particularly the di-ureters of fasphonic acids, and their monoesters, and phosphinic acids. Among the carboxylic acids that give good results, it is worth mentioning the acids constituting the mixture of acids known under the name of isostearic acid. The system of. advantageously the isostearic acid itself. The initial melting point of the amphiphilic acid system (s) Cs 1 is advantageously less than 50 ° C, more advantageously less than or equal to 20 ° C, preferably at most equal to 0 ° C. For a good stability and for a good extraction, it is desirable that the molar ratio between the extractant and the (X) metal (s) fefravalent Xr), preferably the cerium, is between 1.1 and 0.6, preferably between 0 ^ 2 and 0. ^ This relationship grows when the size of the particles decreases. In order to obtain particularly good sols, preferably at least 5%, advantageously at most preferably at least 0.3 by mass of X-oxide particles of tetravalent metal (s) (s) are at most equal to 100 nm, advantageously at 50 nanometers, preferably at 20 nanometers Any diluent leading to a stable role falls within the scope of this invention The sols according to the present invention can be used according to numerous applications. , it is appropriate to select a copipromy or taking into account the technical data given below: - for synthesis and stability, it is desirable to avoid very apolar hydrocarbons * such as, for example, cyclic aliphatic hydrocarbons-, - diluents, such as esters or ethers, have a function poXax qua buanor rasult two, but for certain applications can be avoided as far as possible.The mixture of diluents can provide a so tion, compensating the non-polarity of certain diluents by the adjunction of polar compuertor., in general solvents. According to a particularly advantageous application of the present invention * the sun is used to form a sol diluted in a garólec £ 1 initial sun is generally very concentrated. On the other hand, for reasons of compatibility with diesel and its numerous additives, Xos dULuenfer are preferably not very polar. As a constituent of a diluent, the aromatic or aliphatic compounds are preferable to the compounds having a polar function, such as for example JThe functions of esters or ethers. It is preferable that the diluents have a Butanol ratio (measured according to ASTM D 11 33) lower than X 05 ^ lower than n0.9. For use as an introduced additive, it is preferable that the melting point of the diluents, or mixture of diluents, be low and sensitive to the melting point constrictions described in this title to the propound of the amphiphilic acid system. It is also preferable that these diluents have a very low solubility in water, preferably less than 5% by mass, preferably at Xc plus 1%, more preferably at most equal to 0.5% by mass. Symmetrically, it is also preferable that the water be soluble in at most 5% * preferably at most in 1%, more preferably at most 0.5% in the diluent. Among the preferred diluents, mention may be made of aromatic hydrocarbon compounds and mixtures thereof, and also aliphatic compounds and mixtures thereof, which contain less than 50%, preferably 25%, or more preferably .1% de. aromatic compounds-. The oxides of the tetravalent metal (s) may contain proportions that are substantially free of metals that have other valences. In general, the proportion of addition elements, or impure, contained in the tetravalent metal particles (s), does not exceed ΔO% in maram, more particularly 5% by mass. ) the sun according to the invention is advantageously at most equal to 2/3 in mass, preferably between 30 and 40 in mass. For the use as an additive for diesel introduced, it is preferable that Xa. proportion of tetravalent metal (s) does not fall below 1/6, preferably 1/5. The organic roles according to the invention are generally prepared in a known manner by heating an aqueous sol containing the oxide (a) of tetravalent metal (s), in the presence of the diluent and the system amphiphilic acid. According to one of the particularly advantageous characteristics of the invention, it is advisable to ensure that there is no very thick particle in the aqueous sol, and thus in the final so.sup.- The elimination of very coarse particles can be done. by any technique that allows. selectively remove the thickest particles. This elimination can be practiced on aqueous BX S? X, on the organic sun * or both. Nevertheless,. it is preferred that there be at least one separation on the aqueous sol. The preferred technique er Xa centrifugation-. A centrifugation of the aqueous sol corresponding to 1000 to 10,000 G for one hour gives generally good results. It is possible, however, to go to centrifuges corresponding to _5_, OOO_G- It is to be noted that the centrifugation prior to the stage of constitution of the organic sol, frequently called the extraction stage, favors the latter. The a.cnosos suns are a real advantage or by hydrolysis *. preferably by thermohydrolysis. Among the techniques usable by the present invention, one can cite the techniques disclosed in the European patent application p-UbJlcada Jbaje el -nú ero _97,5_5J3 in the name of the Applicant. It is also possible to cite the European patent application published under number 206.907.

The sols obtained according to the invention have a concentration of cerium (IV) compound which can be very high, since it can go up to 3.5 M to 4 M of Ce02. It is found that the extraction performance of the body in the organic phase is very good * since it can reach 90 to 35%. - The organic soils and 1 abcra-two have an excellent stability. Decanting is not observed after several months. According to one of Xas preferred characteristics of For. present invention * the sun is such. that * adjusted to a concentration of metallic cerium content of 30% _, the viscosity of the sol at 25 ° C is at most equal to 20 mPa-sec, advantageously at 1.5 mPa-sec, gives prafarenci.a at 10 mPa.sec. This viscosity can be measured by a "low shear" device of the Confrayes brand, varying from the velocity gradient of 0.01 to 1 sec. "It is also preferable that Xas against anions of the cerium solution of the sun, are not more present in the various sols according to the present invention rather than in a proportion at most equal to 0.1, advantageously at .0..D5, preferably at 0-03 equivalents per 100 grams of cerium dioxide.

The organic oxides thus obtained can be diluted to obtain concentrations of 10 to 500 ppm *, preferably of 5 D a, 200 ppm in tetrahydric metal (SBS). The d ^ luenie is advantageously a fuel -.for internal combustion engines, preferably diesel. Thus, the invention also focuses on selles whose organic phase is essentially constituted by diesel and additives. Another object of the present invention is the method. pxep > axacX? n .de .Xa composition cited Previously ^ This preparation process is characterized by the fact that it is mixed with less than one organic compound of at least one alkaline earth metal and, if necessary, at least one organic compound of at least one alkaline metal. , with the organic sun cited above. G nera 3.mente. The proper amount of metal (tetrahedral) / sum of the tetravalent metal (s), alkaline earth, and optionally alkaline elements * is at least 50%, more particularly at least 70% . The invention also relates to the use of the compositions. The compositions of the invention can be used as dryers in the paint and varnish industry, in order to accelerate the drying of the unsaturated oils. They can also be used as adjuvants. of combustion in the fuels or liquefied fuels of the energy generators such as the explosion engines, heavy oil burners, or reaction propellants. The compositions of the invention are more particularly suitable as an adjuvant for diesel fuels. Examples cctxcxetos but not limifanter go to. SBX dice ahpra.

EXAMPLES Reagents Unless otherwise provided, read reagents used in the examples are: - a previously neutralized nitrate at r = + 0.5 (compare the European patent in the name of the published Applicant download No. 153, 227) - an extracting agent of oleic acid, which can be replaced without modification by JLa olina (10 oleic acid + 30% linoleic acid) - a solvent, SOLVESSO 150, which is not specific, and can be replaced by ISOPAR JL, the Jaexano or even diesel.

General operative mode The operative mode of Xos examples er the following .: the first ^. stage consists of Xa synthesis of the precursor, which is an aqueous sol of Ce02 colloids whose size (MET) is comprised of 3 and 3 pipi. The ceric nitrate solution of r = + Q _ 5 is placed in an autoclave lined with tantalum. JThe concentration of the solution used is 60 g / 1 expressed in Ce02. ^ operation in the autoclave re raLLLza _a 1J80 ° C for.4 hours, with an increase in temperature in 1 hour. Agitation was maintained throughout the operation. At the end of the operation in the autoclave, the product is decanted and then separated (filtered and drained) from the mother liquors. Then it was again dispersed in water, which allowed to obtain a stable aqueous sol. The concentration of this sol was 150 g / 1.

EXAMPLE 1 Reagents a previously neutralized céx co nitrate of r = +0.5 and at a concentration of 60 g / 1 in cerium, - an oleic acid extractant. First stage: The CBXXCO nitrate solution of r = + 0._5 er placed in an autoclave lined with tantalum. The concentration of the solution used is 80 g / 1 expressed in Ce02. The operation in the autoclave re realizes at 1.80 ° C hard and -4 koxas, can. an increase in temperature in 1 hour. ^ The stirring was maintained throughout the operation. The solution-obtained was filtered ro-br-e sintered glass NQ .. 4. The product was then redirpersade in water, XO which allowed to obtain a stable aqueous sol. The concentration of this role was 150 g_ / l. Second stage: The second stage of Xa preparation. The transfer of the colloids from the aqueous phase to the organic phase. In a round-bottomed flask, a dosed amount of aqueous sol of Ce02 was placed, to which was added the organic mixture, which was such that the oleic acid oleic acid read / cario was Q.3, and the. SOLVESSO 150 / oXeic acid ratio was _3.73. In. In the example considered, this led to the use of: - 24.8 g of Cep2 io s ea 0.165 1 of S OX of 1J50 q) -, - 12.2 g of oleic acid * - 45.7 q? _S £ _LVE ____ 3Q 1-5-0. The mixture was then heated to 100 ° C under reflux for about X0 Jieras. After cooling. The organic phase was separated from the aqueous phase, and then a hydrophobic filter was filtered over it. The exact value of the sol was then measured by calcination (after four hours at 950 ° W). A.sX was obtained a role of erfability measured over 4 months (duration of the sample), whose concentration in BX.a of _2_9._1 (z asa), and whose size of. colloids measured by MET) was between 3 and 5 nm.

EXAMPLE 2 Mixture of an organic cerium sol and a strontium salt according to the invention A starch sap or the polyisobutylene succinic anhydride of molecular weight 420 Sr-PIBSA 420 was prepared, such as. HE . describes in Xos ej.emplor JL3 and 14 of patent WO 96/34074 of the QCTEL Company. ße proceeded, a. followed by a mixture of the organic cerium szoX described in Example 1 with the salt Sr-PIBSA 420 in the following proportions:,: 90% mol de cerium and 10% molar of Mr.

EXAMPLE 3 Mixture of an organic cerium sun and an erroneous salt according to the invention The procedure was as in Example 2, applying the organic cerium sol and the Sr-PIBSA 420 salt in the. siguianfer proportions. 75% oTLar of cari o and 25 molar% of -Sr.

-Efficiencies-; measurement of the inflammation temperature of the soot It proceeded in the manner _sig. ?? i enie_ A carbon black, which is known to be produced in a productive way (ref: ELFTEX 125 No. 137 of house) was selected for these properties in terms of particle size and specific surface area. These, respectively, of 60 nm and 30 m2 / g are of the same order of size as JLar particular carbon emitted at the exhaust outlet of a diesel engine. This carbon dioxide was impregnated with the additive to obtain a final content of 15%. in weight equivalent in metal (Ce + SrJ) This content is representative of what can be obtained in the particles emitted in the exhaust of a diesel during the application of an additive in the diesel oil The impregnation was carried out in the same way as the supported catalysts are prepared by the so-called impregnation technique in SBCO.-The carbon black and the desired amount of additive were intimately mixed in a glass vessel until a homogeneous paste was obtained. The first step in the analysis of the Gravimetric Thermal Analysis (ATG) of the combustion in air of this impregnated carbon black allowed to put in evidence the more or less large catalytic effect thus generated by the presence of the additive. considered as much more active as the corresponding temperature of the beginning of carbon combustion during the ATG s ^ a Jorja- An essay made with black of carbon not impregnated with additive serves as a reference. The ATG was performed with a load of 20 to 25 mg of carbon black * in a cauda. of 3.5 Ui / Jir air, and. with a temperature setting between the ambient temperature and 900 ° C at a rate of 10 ° C / min. For the mixtures prepared according to Examples 1 to 3, the Inflation temperatures were gathered in Q the Table below. Re-sults or ATG-: The results obtained unambiguously show that the temperature of the inflow of the ho.sub.1.1 and n.sub.5 is significantly decreased when the carbon particles are impregnated with an additive consisting of the mixture of an organic ceria and a strontium salt.

Claims (13)

1. CLAIMS 1. Composition characterized in that it comprises an organic sol of particles of at least one oxide of at least one tetravalent metal and at least one organic compound of at least one alkaline earth metal.
2. 2_ Composition according to claim 1, wherein the tetravalent metal is cerium, praseodymium * terbium; in the particular case of the mixture of rare earths, it is preferable that the cerium be present.
3. 3. Composition of r-o nrity with whichever of JLa_s ro-ai di, cac-ionea. __ o. 2 en_ daiide the tetravalent metal is cerium.
4. Four . Composition in accordance with 1 to 1 of claims 1 to 3, wherein the alkaline earth metal is -magnesium, -calcium, -the-tronium, or barium.
5. 5. Composition in accordance with any one of Claims 1 to 4, wherein the composition comprises an organic soX of cerium oxide particles and at least one organic strontium compound.
6. 6. Composition according to any of claims 1 to 5, wherein the composition comprises at least one organic compound of at least one alkali metal.
7. 7. Compound of conformity no cna 1 qui era of claims 1 to ß, wherein the alkali metal is selected from sodium, potassium, and cesium.
8. 8. Composition according to any one of the preceding claims, wherein the SOX comprises: D particles of aX minus a solvent oxide of a tetravalent metal, D a system of amphiphilic acid and D a diluent, and in addition Xas particles they have a d9 ^ _a .XO more equal to -20 nanometers, and have at least one of the following characteristics: • the oxide particles (s) of tetravalent metal (s) are below the ± Ox a of agglomerates of crystallites, whose d9a, measured by photometric counting (electron microscopy by transmission of al solute solution), is at most equal to 5 nanometers, 90% by mass of the agglomerates comprises from 1 to 5, preferably 1 to 3 crystallites, • the amphiphilic acid system comprising at least one LO acid at 50 carbon atoms * has at least one branch in alpha, oeta, gamma and delta of the atom bearing the acid hydrogen.
9. 9. Composition according to claim 8, wherein the particles of tetravalent metal oxide are cerium diocid.
10. 10. Composition according to any of the preceding claims, wherein the diluent is essentially constituted by gas oil and its additives.
11. 11. Composition according to any of the preceding claims, wherein the atomic ratio of. etal jesj tetrava 1. entity i -) Trouma of the metallic elements (s) tetravalente (s), alkaline earth and evenfinally aX-caXXnc s ^ er of aX .. less than 50%, more particularly of at least 70%.
12. 12. Process for preparing a composition according to any of claims 1 to 11, wherein at least one organic compound is mixed. at least one alkaline earth metal and if necessary at least one organic compound of at least one alkali metal, with the organic sol.
13. 13. Fuel for internal combustion engine, where the eroformed fuel is mixed with a conventional fuel of a composition according to any of claims 1 to 11. L4 .. Use of the compositions of. conformity with any Xas rei ndi ae.i or is 11 as adjuvant diesel for diesel engine.