MXPA98009188A - Preparation of solid, powdery rare earth carboxylates by evaporation method - Google Patents

Abstract

A process for producing solid, powdery carboxylates of Rare Earths (RE) elements, among them mainly Nd, La, Pr and Ce, where the ligands coordinated to the metal are long-chain, branched carboxylic acids is provided. Preferably, the carboxylic acids are selected from the group consisting of:2-ethylhexanoic, neodecanoic, versatic and naphthenic acids.

Description

PREPARATION OF RARE POWDERED CARBOXYLATES, SOLID BY THE EVAPORATION METHOD DESCRIPTION OF THE INVENTION The present invention relates to methods for producing rare earth carboxylates in powder, solids using solvent evaporation. The production of rare earth carboxylates in powder form, solids with branched large chain ligands (for example 2-ethylhexanoate, versatate, neodecanoate or rare earth naphthenate) by conventional methods, produces oily, sticky wax-like materials which after drying (from about 60 to about 90 ° C) are difficult to convert into powder materials. One reason for this may be the branched structure of these ligands. The two carboxylic acids which are less likely to give powder solids, the versatic acid, and neodecanoic, consist of mixtures of neodecanoic acid isomers in addition to their branched nature. Naphthenic acids consist of monocarboxylic acids of different molecular weight and may contain a variety of hydrocarbon impurities. 2-Ethylhexanoic acid (octoic acid) is available in isomer-free form. Another reason for the sticky consistency may be the fact that during the formation of these materials several impurities remain incorporated in the product and it may be difficult to remove them by the usual purification steps. Especially, salts such as nitrates, chlorides, sulfates and the like can be trapped in the product if the method does not offer an easy way to extract these salts, moreover, if the solvent medium consists of polar solvents, such as water, or alcohols, such as methanol or ethanol, or ethers, such as THF or DME, the final product may also be contaminated with these. An additional source of impurities is the so-called "free acid", which will be present in the product if part of the carboxylic acid starting material remains unreacted. The presence of the free acid can prevent the formation of powdered materials. For example, cerium octoate 4+ is a solid, but in the presence of a molar equivalent of the free acid the product is an oil. Due to the complexity of the structure of the final product, even if the theoretical stoichiometry of the reaction does not allow the formation of unreacted acids the final product may possess a percentage of unreacted acid present. In other cases, where stable solutions of rare earth carboxylates are of interest instead of powdered materials, it has been found that the impurities mentioned above, such as water or free acid, are good additives, since they tend to coordinate the rare earth metal and allow the molecule to be in solution and thus avoid the formation of structurally more sophisticated systems which in turn can be separated by precipitation as waxy materials or viscous oils. European Patent 0 599 096 Al (to Mic elin; 1 of June 1994) describes the preparation of solid neodymium octoate by a precipitation reaction in water from NdCl3 and sodium octoate at 90 ° C. No information is provided on the consistency of the material. The majority of the literature deals with the preparation of rare earth carboxylates with ligands other than 2-ethylhexanoic, neodecanoic, versaic and naphthenic acid. We report the synthesis of laureate, palmitate, scandium stearate (from ScCl3 and NaOOCR in ethanol) and the synthesis of cerium (III) octanoate (from Ce (N03) 3 and octanoic acid in water) along with data spectroscopic and physical (from: GMELIN Handbook, Rare Earths Main Vol. D 5). It is an object of the present invention to provide means for the preparation of solid powdered carboxylates of 2-ethylhexanoate, neodecanoate, versatate and neodymium naphthenate, with emphasis on techniques that promote the powder consistency of these products. The present invention relates to the production of solid carboxylates, in dust of Rare Earth elements (ER), such as Nd, La, Pr and Ce, where the ligands coordinated to the metal are carboxylic, large chain, branched acids. Preferably, carboxylic acids are selected from the group consisting of: 2-ethylhexanoic, neodecanoic, versatic and naphthenic acids. The process comprises the following steps: 1) Preparation of a concentrated solution of the rare earth carboxylate (up to about 12% of ER content, preferably neodymium) in a hydrocarbon solvent comprising up to about 3% water as a stabilizer and up to 12% % of free acid or preferably that is substantially free of free acid (less than about 1%) or that has no free acid; and 2) Azeotropic solvent distillation. Unless stated otherwise, all parts, proportions or percentages are by weight. Unless otherwise stated, all molecular weights are averages in mass. "Understanding" as used herein means that various components can be used together.

Accordingly, the terms, "consisting essentially of" and "consisting of" are encompassed in the term "comprising". The full description of the previous provisional request, 60 / 040,327, is considered as being part of this description and is incorporated by reference for the same. The scope of the invention comprises the preparation of rare earth, powder, solid, branched-chain carboxylates, evaporating a highly concentrated solution to dryness. Preparation of rare earth carboxylate solutions A method for preparing highly concentrated and stable solutions of the rare earth carboxylates mentioned above by reacting a carboxylate salt with a rare earth salt in a medium of two solvents, for example: Reaction of the carboxylate salt with ER ER (N03) + 3R-COONa nitrate? ER (OOC-R) 3 + 3NaN03 Nitrate Carboxylate ER byproduct of ER dissolved in organic water dissolved in organic solvent (ER = Nd; R = versatate) Immediately after the addition of the rare earth salt, the carboxylate is formed of rare earth; but, due to its solubility in cyclohexane, it dissolves rapidly in the organic layer (the carboxylate solution). However in the absence of any stabilizers, precipitation may occur. The stabilizer to be used is water. The water needed for the dissolving stabilization dissolves in the organic layer. It has been found that the amount of stabilizing water is dependent on the concentration of the solution. Highly diluted solutions (for example from about 2 to about 5% Nd content) require less stabilizer (for example about 1% water) while concentrated solutions (for example from about 10 to about 12% Nd content) require more of the stabilizing agent (for example from about 2 to about 3% water). Generally, carboxylate solutions may comprise from about 0.005% to about 3%, preferably from about 0.5% to about 3%, and more preferably from about 1% to about 2% water. Generally, carboxylate solutions may comprise from about 0.005% to about 12%, preferably from about 0.005% to about 9%, more preferably from about 0.005 to about 6% and more preferably from about 0.005 to about 3% acid free. Generally, carboxylate solutions may comprise from about 2% to about 12%, preferably from about 6% to about 12% and more preferably from about 10% to about 12% of ER. The preferred invention relates to highly concentrated, but stable solutions of Rare Earth carboxylates substantially free of the free acid (less than about 1%, preferably less than about 09.5% and more preferably less than about 0.1%, preferably less than about 0.5% and more preferably less than about 0.1%) and its ability to produce solid, rare earth powder carboxylates. The next stage of the synthesis is the removal of the aqueous layer by conventional methods and washing of the organic layer preferably with water. The washing step is essential since it removes impurities such as saline byproducts and unreacted starting materials, which can prevent, in subsequent steps, the formation of powdered materials. Elimination of solvents and drying conditions The final stage of the synthesis is the elimination of solvents by evaporation methodology. This is done under usual distillation conditions with or without applying any vacuum. Any conventional drying or drying technique can be used. The preferred dryer has characteristics to ensure the formation of a powder product. These characteristics are high mixing of powder and an agitator capable of providing homogeneous mixing and promoting even heat transfer. Suitable agitators are described in EP 0577456A1 published on January 5, 1994, Bertrand et al. (PIERRE GUERIN S.A.), which is incorporated herein by reference. This results in a low temperature difference between different areas of the material (high heat transfer coefficient), and good product renewal due to mechanical ation which prevents the formation of dead zones. The solid, powdered, rare earth carboxylates are useful as catalyst components for the polymerization of conjugated dienes, such as butadiene, isoprene, 1,3-pentadiene or a mixture thereof. Preferably, the ER carboxylates of the present invention are used for the polymerization of butadiene. Components Carboxylic acids suitable for use include aliphatic, cycloaliphatic and aromatic mono and polybasic carboxylic acids. The acids can be saturated or unsaturated, straight-chain or branched. The organic carboxylic acids can be either natural or synthetic mixtures thereof. Examples of natural acids, although usually refined, include straight and branched chain carboxylic acids and cyclic carboxylic acids such as naphthenic acid. A variety of synthetic carboxylic acids and particularly aliphatic or alicyclic monocarboxylic acids or mixtures thereof are useful. Preferred are large chain, branched carboxylic acids. The organic carboxylic acids will preferably contain from about 6 to about 32 carbon atoms, preferably from about 5 to about 18 and more preferably from about 8 to about 10, but when more than one of the acids is employed, carboxylic acids can be employed which they contain as little as about 5 carbon atoms or as little as 2 carbon atoms as one of the acids in the mixtures. Examples of useful organic carboxylic acids include 2-ethylhexanoic acid, neodecanoic acid, and commercially available mixtures of two or more carboxylic acids such as naphthenic acids. The acid number for the preferred naphthenic acid is from about 160 to about 300 mg KOH / g. The carboxylic acids for use herein are naphthenic acid (preferably having an acid number from about 160 to about 300 mgKOH / g), neodecanoic acid (also referred to as versatic acid), and 2-ethylhexanoic acid. The term "neodecanoic acid" as used herein refers to mixtures of branched carboxylic acids, generally predominantly about 10 carbon atoms. These mixtures of acids will generally have an acid number from about 310 to about 325 mg KOH / g. Commercially available neodecanoic acids are provided by Shell under the trademark, "Versatic 10" and by Exxon under the name "Neodecanoic Acid". These acids are well known and are described in, for example Kirk-Othmer, Encyclopedia of Chemical Technology, fourth edition, John iley &; Son, New York 1993, Vol. 5, p. 147-192, which is incorporated herein by reference. The amount of the carboxylic acid used may vary, although it is generally preferred that the molar equivalent ratio of the rare earth element to carboxylic acid is at least about 1: about 3 to about 4. A carboxylic acid salt solution can be prepared by reacting the carboxylic acid with a base which is an alkali metal, alkaline earth metal or ammonium oxide, hydroxide, carbonate or carbonate (preferably tetra (lower alkyl) ) ammonium). The suitable base for reaction is preferably a hydroxide of an alkali metal of Group I, preferably lithium, sodium or potassium. More preferably the base is a sodium hydroxide. Bases suitable for use include: sodium hydroxide, lithium hydroxide, potassium hydroxide, tetrabutylammonium hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide. The reaction of the carboxylic acid and base preferably occurs in the presence of water to form the carboxylic salt solution. The carboxylic salt, preferably in the form of a salt solution, is then preferably reacted with a Rare Earth nitrate (ER (N03) 3) to produce the Rare Earth carboxylate. This is preferably carried out in the reaction medium of water and hydrocarbon solvent. The Rare Earth nitrates suitable for use are the nitrates of Group III B of the periodic table (lanthan series, gone). Rare Earth Nitrates suitable are, for example, the nitrates of lanthanum, cerium, praseodymium, neodymium, promised, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. Due to their similar properties, yttrium and scandium can also be used. Neodymium, lanthanum, praseodymium and cerium nitrates (preferably Ce III) are preferred for use. More preferred are neodymium nitrates. Other water-soluble salts of Rare Earth such as Rare Earth chlorides may be used. It is more desirable to carry out the reaction of the carboxylic salt with a Rare Earth nitrate in a medium of two solvents comprising water and hydrocarbon solvent such as n-hexane, cyclohexane or toluene. The hydrocarbon solvents for use may be aliphatic, cyclic (alicyclic), or branched hydrocarbons, such as butane, pentane, hexane, cyclohexane, heptane or toluene or a mixture thereof. It is preferable that the hydrocarbon solvent is inert (unreactive) of low boiling point or relatively low boiling point in nature. While specific embodiments of the invention have been described in the Examples, it will be appreciated by those skilled in the art that various modifications and alternatives may be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements described are understood to be illustrative only and not limiting to the scope of the invention which is given in the entire contents of the appended claims and equivalents thereof. Example 1: Preparation of solid neodymium versatate The following charges are made in a Turbosphere® 50 liter reactor (available from PIERRE GUERIN S.A.): Water 4 kg, and caustic soda solution 2.48 liters (concentration 298 g / l): Agitation is started and versatic acid (MW = 173) 3.2 kg is fed in approximately 10 minutes.

In the clear solution, add 20.56 liters of hexane and bring the mixture to 35 ° C. 2.1 liters of an aqueous solution of neodymium nitrate (content of Nd203 497 g / l) is added in approximately 30 minutes. The mixture is stirred for 30 minutes. The aqueous layer is removed. The upper organic layer is washed once with 4.8 liters of water and distilled under atmospheric pressure to 85 ° C. Then the pressure is gradually reduced to approximately 30 Torrs. A blue powder of neodymium versatate (3.9 kg) is obtained. Example 2: Solid neodymium ethylhexanoate in a Turbosphere dryer The following charges are made in a Turbosphere® 10 liter reactor (available from PIERRE GUERIN S.A.): Water 1500 g, anhydrous caustic soda 278 g. Agitation is started and 1000 g ethylhexanoic acid (MW = 144) is fed in 10 minutes. In the clear solution, 3600 g of toluene is added and the mixture is brought to about 30 to about 50 ° C. 1364 g of an aqueous solution of neodymium nitrate (concentration 497 g or Nd203 / l) is added in 30 minutes. The mixture is stirred for 30 minutes and then decanted. The aqueous layer is removed. The upper organic layer is washed once with 1200 g of water and distilled under vacuum to about 90 ° C. An azelim powder of neodymium versatate (1400 g) is obtained. Example 3: Polymerization of butadiene with solid neodymium verpatate A 2 liter stainless steel reactor is charged with 350 ml of cyclohexane (water content 35 ppm) and with 40 g of butadiene. To this solution is then added a catalyst mixture consisting of 0.19 g of solid Nd versatate as prepared according to Example 1, 1.5 ml of diethylaluminochloride (1 m solution in hexane) and 5 ml of di-isobutylaluminohydride (1 m). solution in cyclohexane). The temperature is increased to 85 ° C in the next 30 minutes, and it is cooled to room temperature in the following 45 minutes. The polymer produced is separated by precipitation using 500 ml of methanol which contains 0.5 g of BHT. Polybutadiene yield: 38.4 g (96%) Isomer composition: cis 98.5%; 1.3% trans; vinyl 0.2% Molecular weight: 113,000

Claims (30)

1. CLAIMS 1. A process for preparing solid rare earth carboxylates, powder characterized in that it comprises the steps of: a) Reaction of a carboxylate salt and a rare earth nitrate (ER) or other Water soluble ER salt in a solvent who understands; water and a hydrocarbon solvent; b) Removal and washing of the organic layer to produce a solution of rare earth Carboxylate (ER) comprising up to about 12% by weight Rare earth, up to about 3% by weight of water and up to about 12% by weight of free acid; and c) Removal of the remaining solvent by evaporation.
2. 2. The process according to claim 1, characterized in that the carboxylate salt is a salt of carboxylic acids selected from the group consisting of: naphthenic acid, neodecanoic acid, versatic acid, 2-ethylhexanoic acid and mixtures thereof.
3. 3. The process according to claim 2, characterized in that ER is selected from Group 11IB of the periodic table.
4. 4. The process according to claim 3 characterized in that ER is selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, promised, samarium, europium, gadolinium, terbium, dísprosium, holmium, erbium, thulium, ytterbium, lutetium , yttrium and scandium.
5. 5. The process according to claim 4 characterized in that ER is selected from neodymium, lanthanum, praseodymium and cerium.
6. 6. The process according to claim 5 characterized in that ER is neodymium.
7. The process according to claim 6 characterized in that the solution of the ER carboxylate comprises from about 0.005% to about 3% by weight of water, from about 0.00% to about 12% by weight of free acid and of about 2% to approximately 12% by weight of ER.
8. 8. The solution according to claim 1 characterized in that the free acid is less than about
9. 9. A rare earth carboxylate prepared by the process according to claim 1.
10. 10. A characterized rare earth carboxylate solution comprising: a) rare earth carboxylate (ER), b) a hydrocarbon solvent, and c) about 0.005% to about 3% by weight of water, and d) from about 0.005% to about 12% by weight of free acid; The solution according to claim 10, characterized in that the ER carboxylate is selected from the group consisting of: ER 2-ethylhexanoate, ER versatate, ER neodecanoate, ER naphthehenate and mixtures thereof. 12. The solution according to claim 11, characterized in that ER is selected from Group IIIB of the periodic table and yttrium and scandium. The solution according to claim 11, characterized in that ER is selected from lanthanum, cerium, praseodymium, neodymium, promised, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. 14. The solution according to claim 13, characterized in that ER is selected from neodymium, lanthanum, praseodymium and cerium. 15. The solution according to claim 14, characterized in that ER is neodymium. 16. The solution according to claim 15 characterized in that the free acid is less than about 1% by weight. 17. The solution according to claim 11, characterized in that the free acid is selected from the group consisting of naphthenic acid, neodecanoic acid, versatic acid and 2-ethylhexanoic acid. 18. A process for preparing Rare Earth carboxylates characterized in that it comprises the steps of: a) Reaction of a rare earth nitrate and a naphthenic acid carboxylate salt, neodecanoic acid, versatic acid, 2-ethylhexanocyan acid or mixtures thereof , in a Medium of two solvents comprising water and hydrocarbon solvent; b) Removal and washing of the organic layer; and c) Elimination of solvents by evaporation. 19. The process according to claim 18, characterized in that ER is selected from Group IIIB of the periodic table, scandium and yttrium. 20. The procee in accordance with the claim 19, characterized in that ER is selected from lanthanum, cerium, praseodymium, neodymium, promised, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetia. 21. The process in accordance with the claim 20, characterized in that ER is selected from neodymium, lanthanum, praseodymium and cerium. 22. The process in accordance with the claim 21, characterized in that ER is neodymium. 23. The process according to claim 18, characterized in that the free acid in the organic layer after step b is less than about 1% free acid. 24. The process according to claim 18, characterized in that the free acid is selected from the group consisting of naphthenic acid, neodecanoic acid, versatic acid and 2-ethylhexanoic acid. 25. A rare earth carboxylate prepared by the process according to claim 18. 26. A process for the polymerization of one or more diene conjugates by means of a catalyst comprising an ER carboxylate prepared by the claim process. 1. The process according to claim 26, characterized in that the conjugated diene is butadiene, isoprene, 1,3-pentadiene or a mixture thereof. 28. A process for polymerizing butadiene by means of a catalyst characterized in that it comprises a carboxylate of ER prepared by the process of claim 1. 29. A process for polymerization of one or more monomers of conjugated dienes characterized by the use of a catalyst comprising a carboxylated ER prepared by the process of claim 18. 30. A process for polymerizing butadiene characterized by the use of a catalyst comprising a carboxylated ER prepared by the process of claim 18.