MXPA00003631A - Composition based on a grafted metal oxide, preparation and use in a polymerisation method by opening oxygenated cycles - Google Patents

Abstract

The invention concerns a composition based on a grafted metal oxide, its preparation and its use in a polymerisation method by opening oxygenated cycles such as alkyl oxides, cyclic esters or cyclic carbonates. Said composition comprises a support selected in the group of metal oxides capable of having hydroxyl functions, whereon is grafted a group of formula (1):M(OR)n in which M is an element selected among scandium, zirconium, hafnium, niobium, tantalum, rare earths and actinides;R is an organic group and n is whole number not less than 1. The composition is prepared by forming a suspension of said support, then contacting and reacting said suspension with a compound of formula (2):M(OR)n+1 in which M, R and n are defined as above.

Description

CATALYTIC COMPOSITION, BASED ON GRAFT METAL OXIDE, ITS PREPARATION AND ITS USE IN A PROCESS OF POLYMERIZATION BY THE OPENING OF THE OXYGENED RINGS The present invention relates to a catalytic composition, based on a grafted metal oxide, to its preparation and its use in a polymerization process by the opening of the oxygenated rings. Polymerization by the opening of oxygenated rings, for example lactones or lactides, is well known. The metal alkoxides are used as initiators for the reaction. These initiators are used - in a homogeneous medium and found to be effective. However, they have certain drawbacks. First, its solubility is low. In addition, during its use, the addition of alkoxide molecules occurs, leading to the existence of several families of active centers, which results in the production of a wider distribution of the molecular mass of the polymer obtained. Finally, it is sometimes difficult to separate the initiator from the formed polymer, thus compromising the purity of this polymer. It would thus be desirable to have a heterogeneous catalyst available. WO 95/29755 discloses a heterogeneous catalyst, in which the niobium is bound to a support. However, this catalyst is used in a reaction to convert an olefin to another olefin. An object of the invention is to provide a catalyst, which can be used for the polymerization by the opening of the oxygenated rings With this objective, the composition of the invention comprises a support, chosen from the group of metal oxides capable of containing hydroxyl functions, on which a group of the formula (1) is grafted: - (OR) n, in which M is a selected element of scandium, zirconium, hafnium, niobium, tantalum, rare earth metals and actinides , R is an organic group and n is an integer greater than or equal to 1. The invention also relates to a process for preparing this composition, which is characterized in that a support suspension is formed, mentioned above, and this suspension is then placed in contact and reacts with a compound of the formula 2: M (OR) n + 1, in which M, R and have the above definitions Finally, the invention relates to a polymerization process by the opening of the oxygenated rings , the c It is characterized in that a composition, as defined above, is used as a catalyst, in the presence of a protic compound. Other features, "details and advantages of the invention will emerge even more fully from the reading of the following description, as well as from the various concrete examples, but not limiting, which attempt to illustrate it.The composition of the invention comprises a support, which it is selected from the group of metal oxides capable of containing hydroxyl functions (-OH functions), which include, for example, cerium oxide Ce02, titanium oxide Ti02 and thorium oxide. combinations or mixtures of these oxides The Ce02 / Zr02 mixtures may be more particularly indicated, the respective proportions of the two oxides possibly varying within wide ranges.

Mention may also be made of the silica / alumina or zeolite combinations. The support for the composition of the invention comprises, grafted to its surface, a group of the formula Cl), -M (OR) n. The term "grafted" means that the group is chemically bound to the support, in particular, by a covalent bond. This grafting takes place using the hydroxyl groups on the support to provide a binding sequence -O-M (OR) n, where A represents the metal element of the support. In the case of silica, for example, and using its silanol groups, this will give Si-O-M (OR) n binding sequences on the surface of the support. In the group of formula (1), M is selected from scandium, zirconium, hafnium, niobium, tantalum, rare earth metals and actinides. The expression 'of "rare earth metals" means the elements of the group consisting of yttrium and the elements of the Periodic Table of atomic number between 57 and 71 inclusive. The element M may be, more particularly, yttrium, lanthanum, samarium or neodymium.

In the case of actinides, M can be, more particularly, uranium. R is an organic group. Generally it is a group containing from 1 to 100 carbon atoms, in particular from 1 to 50 carbon atoms. R may comprise one or more heteroatoms, such as halogens, nitrogen, oxygen, sulfur and phosphorus. R may be, more particularly, a linear or branched, "saturated or unsaturated, alkyl group, or an aryl group, an aralkyl group or an alkaryl group, In accordance with a specific embodiment, - R is an alkyl group comprising 1 to 18 'carbon atoms, such as a propyl group.

The value of n is not greater than v-1, where v is the maximum valence of element M. "Preferably, the support is one that has been subjected to a heat treatment, the purpose of which is to remove the free or adsorbed water, On the one hand, and, on the other hand, the control of the density or the content of hydroxyl functions in the support, this content can be chemically tested, for example by the reaction of triethylaluminum and the measurement of the volume of ethane gas developed Thus it is sought by this thermal treatment to obtain a density of hydroxyl functions that allow the metal to be attached to the support, as much as possible, by a single chemical bond In the case of silica, a silica with a specific surface BET of about 100 to 700 m2 / g, more particularly between 250 and 350 m2 / g, is preferably used.For alumina, this surface may be between 150 and 250 m2 / g.The term "specific surface" means the surface BET determined by nitrogen adsorption, according to the * ASTM D 3663-78 standard, established by the Braunauer-Emmett-Teller method ("BET"), described in the newspaper "Journal of the American Chemical Society, 60_, 309 (1938)". The process for preparing the composition of the invention will now be described. This process comprises the formation of a suspension of the support and the reaction of this suspension with a compound of the formula (2), M (OR) n + 1. The reaction takes place between the hydroxyl groups of the support and this compound, to give the bonds described above. Preferably, the suspension is formed and the reaction is carried out under anhydrous conditions and in a solvent, for the compound of the formula (2). "The solvent is in general an anhydrous, polar or non-polar aprotic liquid.

It can be selected more particularly from products that are liquid under the conditions of normal temperature and pressure, for example hexane, benzene, toluene, xylenes, 1,2-dichloroethane, acetonitrile, dimethyl-sulfoxide, dimethylformamide and hexamethyl-phosphorotriamide. The reaction is preferably carried out with an excess of the compound of the formula (2), relative to the number of hydroxyl sites (-OH) present on the surface of the support. This excess can be from 1.5 to 2 times the number of hydroxyl sites. The reaction is carried out by heating the reaction medium to a temperature which is not critical, which depends, in particular, on the nature of the solvent and which may be, for example, between 40 and 100 ° C.

After the reaction, the product obtained is separated from the reaction medium by any known means and kept under an anhydrous atmosphere. After separation of the reaction medium, it can be washed with the aforementioned solvent. Finally it dries. If necessary, it can be stored in this same solvent. According to a preferred variant, the support is subjected to a previous heat treatment. As indicated above, the purpose of this thermal treatment is to obtain a support without free or adsorbed water and with a controlled content of hydroxyl functions. This heat treatment is usually carried out by heating at temperatures between 130 and 900 ° C, under vacuum or under an inert gas. These temperatures depend "on the nature of the support, they must be high enough to allow the removal of free or adsorbed water and control of the content of the hydroxyl functions., but they must not exceed the temperatures of the beginning of the sintering of the related support. Infrared analysis, for example, of the heat-treated support makes it possible to check whether or not the water has been truly removed, after which the hydroxyl functions are tested in the manner described above. During the reaction between the compound of the formula (2) and the hydroxyl groups of the support, a compound of the formula ROH is formed. According to another variant of the invention, this compound of the ROH formula is removed during the reaction, as it is formed. It will be noted that it is possible to carry out the process just described, not by using a support, as described above, but by using a previously inserted support, ie a support comprising the AOM (0R) n binding sequences, as described before, on its surface. In this case, a suspension of the previously grafted support is formed and reacted with a compound of the formula M (0R ') n + 1, in which R' corresponds to the same definition as R, where R and R 'are different under conditions such that the AOM- (OR ') n binding sequences are formed in replacement of the original binding sequences AOM (0R) n. The present invention also relates to the use of a composition, as described above, or that can be obtained by the process described above, as a catalyst in a polymerization process, by the opening of the oxygenated rings. As products containing an oxygenated ring, which are capable of being polymerized, mention may be made of alkyl oxides, such as ethylene oxide or propylene oxide.; cyclic esters, such as lactones or lactides, or cyclic carbonates. The invention also applies to the copolymerization of products containing an oxygenated ring, with each other or with C02. The polymerization is carried out in the presence of a protic compound. This protic compound can be chosen from carboxylic acids, alcohols, thiols, glycols and polyols. Alcohols of the formula R '(OH) n, in which m is an integer greater than or equal to 1 and R' represents an organic radical containing from 1 to 100 carbon atoms and, more particularly, from 1 to 50 carbon atoms , which optionally comprise one or more heteroatoms, such as halogens, nitrogen, oxygen, sulfur and phosphorus, can be used in particular. R may be, more particularly, an alkyl group, linear or branched, saturated or unsaturated, an aralkyl group or an alkaryl group. The alcohol may also contain reactive functions, such as a function of acrylate, styrene or maleate, or a halogen. Alkyl groups, which may be -mentioned more particularly, are isopropyl, hexyl and dodecyl. An aralkyl group that may be mentioned is benzyl alcohol. Groups comprising a heteroatom, which may be mentioned, * are polyethers and perfluoroalkyls. As specific re-active functions or alcohols comprising a halogen, mention may be made of hydroxyethyl methacrylate, hydroxymethylstyrene and bromoundecanol. - - - Protic compounds which can be used are the organic acids of the formula R'CO- (0H) m, where m has the above definitions. Mention may be made, for example, of the half ester of maleic anhydride. The polymerization is usually carried out in a solvent medium. A solvent for the formed polymer is chosen. This is an anhydrous aprotic solvent of the type described above. The polymerization is carried out at a temperature which is sufficiently high to give the reaction medium a viscosity which is not too high. Also, this temperature should not be too high, in order to avoid side reactions. Generally, the temperature is between 40 and 80 ° C. The reaction time can vary within a relatively broad range. This time can be from 1 minute to several hours. ___ The catalytic reaction is carried out according to the usual processes for reactors using solid catalysts and liquid effluents, in particular in a stirred bed or in a fixed bed, in a continuous or intermittent process. The compositions of the invention were found to be particularly advantageous for carrying out the ring-opening polymerizations in the heterogeneous mode, these polymerizations have the characteristics of active polymerizations and allow control of the molar mass by means of the amount of the protic compound aggregate. They allow the production of polymers of improved purity and a narrow distribution of molecular mass, as do block or random copolymers. Finally, the compositions of the invention can be reused after the polymerization and after a simple washing with a protic compound, which is identical to or different from that used for the first polymerization. - The compositions of the invention with an alumina support are effective more particularly for the polymerization of the alkyl oxides, especially the ethylene oxide or propylene oxide. Compositions with a silica support are effective, in particular, for the polymerization of cyclic esters of the lactone type or cyclic carbonates. Examples of the invention are now provided.

EXAMPLE 1 Production of a silica functionalized with yttrium isopropoxide The Grace 432 silica was used, previously treated in thermal form under the following conditions. The silica was heated from room temperature to 100 ° C in 30 minutes, then from 130 to 450 ° C in 1 hour and finally at 450 ° C for 2 hours. The cooling took place under a dynamic vacuum. 1 g of this silica, suspended in 20 ml of toluene, dried in 0.3 nm molecular sieves, was introduced, under argon, into a Schlenck tube, followed by 2.2 ml of a 25 wt.% Isopropoxide solution. (0.0018 mole of yttrium isopropoxide) (commercial solution in toluene, reference Strem 39-3000). After the reaction for 3 hours at 50 ° C, the solid was washed with three times 10 ml of toluene. The residual liquid was removed and the solid was then dried at 50 ° C under the vacuum of a fin pump. The dried solid was kept under argon in a Schlenck tube. The amount of the yttrium isopropoxide bond to the silica is measured by the elemental analysis of yttrium and carbon (Y = 11.4% by weight, C = 2.14% by weight). Under these conditions, there are as many yttrium atoms bound together as hydroxyl functions carried by the silica.

EXAMPLE 2 Polymerization of an e-caprolactone with the yttrium isopropoxide supported on silica, in the presence of isopropanol 500 mg of functionalized silica according to the method of Example 1 (which supports 0.0006 mole of yttrium) was introduced, under argon, into a tube of Schlenck and suspended in 30 ml of toluene, dried in molecular sieves of 0.3 nm, at 50 ° C. 0.45 ml of isopropanol (0.006 mol) and 8 ml of e-caprolactone (0.072 mol) were added to the suspension. The polymerization reaction was monitored by gas chromatography (internal standard: 1), 2-dichloroethane dried in 0.3 nm molecular sieves). The polymerization was completed in 10 minutes. 5 ml of ethanol were added to the suspension to release the polymer chains attached to the silica, and this silica was allowed to separate-by sedimentation. The polymer solution was then filtered and the polymer recovered by evaporation of the solvent under vacuum, in a rotary evaporator. 8.2 g of the polymer were obtained. The polymer was analyzed by proton nuclear magnetic resonance and carbon-13. The average degree in polymerization number was derived from the ratio: incorporated lactone / isopropoxy at the beginning of the chain, and is equal to 10. The NMR analysis showed that there are as many isopropoxy groups at the beginning of the chain as functions of alcohol at the end of the chain, which demonstrates the active nature of the polymerization.

EXAMPLE 3 Production of a silica functionalized with yttrium benzylate and the subsequent polymerization of e-caprolactone 500 mg of functionalized silica according to the method of Example 1 (which supports 0.0006 mole of yttrium) were introduced, under argon, into a tube of Schlenck and were suspended in 30 ml of toluene, dried in molecular sieves of 0.3 nm, at 50 ° C. "1.2 ml of benzyl alcohol (0.012 mol) were added and the mixture was allowed to react to 50 ° C for 1 hour. This mixture was then washed with three times 10 ml of toluene * to remove the released isopropanol and the excess of benzyl alcohol. The supernatant liquid was removed and the solid was dried at 50 ° C under the vacuum of a fin pump. This solid was suspended in 30 ml of toluene. 0.6 ml of benzyl alcohol (0.006 mol) and 8 ml of e-caprolactone (0.072 mol) were added to the suspension. The polymerization reaction was monitored by gas chromatogaphy (internal standard: 1,2-dichloroethane dried in 0.3 nm molecular sieves). The polymerization was completed in 10 minutes. 5 ml of ethanol were added to the suspension to release the polymer chains attached to the silica. After removing the silica by sedimentation, the polymer solution was filtered and the polymer recovered by evaporation of the solvent under vacuum, in a rotary evaporator. 9 g of the polymer were obtained. The polymer was analyzed by proton and carbon-13 nuclear magnetic resonance. The average degree of polymerization was inferred from the ratio: incorporated lactone / benzyloxy at the beginning of the chain, and was equal to 10.

EXAMPLE 4 Production of a silica functionalized with neodymium isopropoxide and the polymerization of e-caprolactone 1 g of silica Grace 432, previously heated at 450 ° C, under the conditions described in Example 1, suspended in 20 ml of toluene, dried in 0.3 nm molecular sieves, was introduced, under argon, into a Schlenck tube, followed by 580 mg of neodymium isopropoxide (0.0018 mol, Strem product, reference 93.6012). After reacting for 3 hours at 50 ° C, the solid was washed with three times 10 ml of toluene, the residual liquid was removed and the solid was then dried at 50 ° C under the vacuum of a fin pump. The dried solid was kept under argon in a Schlenck tube. The amount of neodymium isopropoxide bound to the silica was measured by the elemental analysis of neodymium and carbon (Nd = 15.5% by weight, C = 3.43% by weight). Under these conditions, there are as many bound neodymium atoms as there are hydroxyl functions carried by the silica. 500 mg of this functionalized silica were used for the polymerization of e-caprolactone, according to the method described therein Example 2. The reaction was completed in 30 minutes.

EXAMPLE 5 Production of an alumina functionalized with neodymium isopropoxide ~ An alumina Procatalyse was used, previously treated in thermal form under the following conditions. The alumina was heated from ~ room temperature to 100 ° C in 30 minutes, then 100 to 130 ° C in 30 minutes, then 130 to 200 ° C in half an hour and finally at 200 ° C for 2 hours. The cooling took place under a dynamic vacuum. 1 g of this alumina (containing 1.6 x 10 ~ 3 mol of OH) suspended in 20 ml of toluene, dried in 0.3 nm molecular sieves, placed in a Schlenc tube, under argon, followed by 770 mg of neodymium isopropoxide (2.4 x 10 ~ 3 mol) (Strem product). After the reaction for 3 hours at 50 ° C, the solid was washed with three times 10 ml of toluene, the residual liquid was removed and the solid was then dried at 50 ° C under the vacuum of a fin pump. The dried solid was kept under argon in a Schlenck tube. The amount of neodymium isopropoxide bound to the alumina was measured by the elemental analysis of the neodymium and the carbon (Nd = 8.24% by weight, C = 2.12% by weight). Under these conditions, there are 7.9 x 10 ~ 4 mol of neodymium grafted onto 1 g of alumina.

EXAMPLE 6 Polymerization of ethylene oxide with neodymium isopropoxide supported on alumina, in the presence of isopropanol 500 mg of functionalized alumina, according to the method described in Example 5 (which bears 3.95 x 10 ~ 4 mol of neodymium) were suspended, under argon, in a 250 ml round bottom flask, containing 40 ml of toluene dried on molecular sieves of 0.3 nm and equipped with a magnetic stirrer, a thermal stop, a pressure sensor and a dropping funnel, containing the ethylene oxide, which was previously distilled under vacuum. 0.3 ml of isopropanol (0.004 mol) were added to the flask. The flask was placed under vacuum, using a fin pump (the residual vacuum is the vapor pressure of the liquids contained in the flask) and was encouraged at 55 ° C. 2.4 ml of ethylene oxide (0.048 mol) were slowly added to the suspension. The polymerization reaction was monitored by the pressure sensor. At the end of the polymerization (return to the original pressure), 5 ml of ethanol was added to the suspension to release the polymer chains attached to the alumina. After separation of the alumina by sedimentation, the polymer solution was filtered and the polymer recovered by evaporation of the solvent under vacuum, in a rotary evaporator. 5 g of the polymer was obtained. This polymer was analyzed by nuclear-magnetic resonance of protons and carbon-13. The average degree in polymerization number was deduced from the ratio: incorporated ethoxy / isopropoxy at the beginning of the chain and was equal to 10.

EXAMPLE 7 Production of an alumina functionalized with isopropoxide samarium _ 1 g of Procatalyse alumina, previously treated 450 ° C, according to ~ the method described in Example 1 (containing 0.8 x 10-3 OH OH) suspended in 20 ml of toluene, dried over 3 nm molecular sieves, placed in a Schlenck tube, under argon, followed by 0.393 mg samarium isopropoxide (1.2 x 10" 3 mol) (Product Strem, reference 93.6214) After the reaction for 3 hours at 50 ° C, the solid was washed with three times 10 ml of toluene, the residual liquid was removed and the solid was then dried at 50 ° C. under the vacuum of a fin pump. The dried solid was kept under argon in a Schlenck tube. The amount of samarium isopropoxide bound to alumina was measured by elemental analysis of samarium and carbon (Sm = 3.20% by weight, C = 3.15% by weight). Under these conditions, there are 2.32 x 10"4 mol of samarium grafted into 1 g of alumina.

EXAMPLE 8 Polymerization of propylene oxide with saprobic isopropoxide supported on alumina, in the presence of isopropanol __ 500 mg of a functionalized alumina according to the method described in Example 7 (which supports 1.16 x 10"4 mol of samarium) suspended, under argon, in a 250 ml round bottom flask, containing 40 ml of toluene, dried over 0.3 nm molecular sieves and equipped with a magnetic stirrer, a thermal flask, a pressure sensor and a drip funnel, containing the propylene oxide which has been previously distilled under vacuum, on calcium hydride 0.18 ml of isopropanol (0.0023 mol) were added to the flask The flask was placed under vacuum, using a fin pump (the residual vacuum is the vapor pressure of the liquids contained in the flask) and heated to 55 ° C. 3.5 ml of propylene oxide (0.05 mol) were slowly added to the suspension.The polymerization reaction was monitored by the temperature sensor. At the end of the polymerization (return to original pressure), 5 ml of ethanol was added to the suspension to release the polymer chains attached to the alumina. After separation of the alumina by sedimentation, the polymer solution was filtered and the polymer recovered by evaporation of the solvent under vacuum in a rotary evaporator. 4.4 g of the polymer was obtained. The microstructure of the polymer was determined by proton nuclear magnetic resonance and arbono-? 3. The average degree of polymerization was deduced from the ratio: incorporated propoxy / isopropoxy at the end of the chain, and was equal to 20.

EXAMPLE 9 Production of an alumina functionalized with zirconium isobutoxide and its use for the preparation of block copolymers of propylene oxide / ethylene oxide 1 g of Procatalyse alumina, previously treated at 450 ° C according to the method described in Example 1 (containing 0.8 x 10"3 mol OH) suspended in 20 ml of toluene, dried over 3 nm molecular sieves, placed in a Schlenck tube, under argon, followed by 0.8 ml of a commercial solution of zirconium isobutoxide (Strem, reference 93.4003) After the 3 hour reaction at 50 ° C, the solid was washed with three times 10 ml of toluene, the residual liquid was removed and the solid was then dried at 50 ° C. C under vacuum of a fin pump The amount of zirconium isobutoxide bound to alumina was measured by the elemental analysis of zirconium and carbon (Zr = 1.45% by weight, C = 4.48% by weight).

The product, thus prepared, was suspended, under argon, in a 250 ml round bottom flask, containing 40 ml of dried toluene on sieves and equipped with a magnetic stirrer, a thermal stop, a pressure sensor and a funnel drip, which contains propylene oxide, which has been previously dried on sodium hydride. 0.18 ml of benzyl alcohol (1.76 x 10 ~ 3 mol) was added to the flask. This flask was placed under vacuum, using a fin pump and heated to 55 ° C. 1.6 ml of propylene oxide (0.0299 mol) was slowly added to the suspension. The polymerization reaction was monitored by the pressure drop in the flask. At the end of the reaction, the system was again placed under argon and 40 ml of toluene was introduced. The flask was placed under vacuum and heated to 55 ° C. 1.15 ml of ethylene oxide (0.0299 mol) was added slowly. At the end of the polymerization (return to the original pressure), 5 ml of ethanol was added to the suspension to release the polymer chains attached to the alumina. After the separation of the alumina by sedimentation, the copolymer solution was filtered and this copolymer was recovered by evaporation of the solvent under vacuum on a rotary evaporator 3. g of the copolymer were obtained.This copolymer was characterized by magnetic resonance- Nuclear proton and carbon-13 The alternation of PO-EO • characteristic of the block copolymer is noted in particular.

EXAMPLE 10 Polymerization of 2,2-dimethyltrimethylene carbonate with yttrium benzylate supported on silica, in the presence of -benzyl alcohol _ _ __ _ = __ 500 mg of functionalized silica, according to the method described in Example 1 (which supports 0.0006 mole of yttrium), were introduced, under argon, into a Schlenck tube and suspended in 30 ml of toluene, dried on 0.3 molecular sieves. nm, at 50 ° C. 1.2 ml of benzyl alcohol (0.012 mol) were added and the mixture was allowed to react at 50 ° C for 1 hour. This mixture was then washed three times with 10 ml of toluene to remove the liberated isopropanol and the excess of benzyl alcohol. ~ 0.6 ml of "benzyl alcohol" (0.006 mol) and 7.8 g of 2,2-dimethyltrimethylene carbonate (0.06 mol), dissolved in 75 ml of dry toluene, were added to the suspension.The polymerization reaction was monitored by chromatography. Spherical exclusion and nuclear magnetic resonance of protons, 5 ml of ethanol was added to the suspension to release the polymer chains attached to the silica, this polymer solution was "filtered and the polymer was recovered by evaporation of the solvent in a rotary evaporator . 8 g of polymer was obtained. The polymer was analyzed by proton nuclear magnetic resonance and carbon-13. The average degree in polymerization number was deduced from the ratio: cyclic carbonate incorporated / benzyloxy unit, at the beginning of the chain, and was equal to 10.

Claims (12)

1. Process for the polymerization by opening of the oxygenated rings, characterized in that a composition is used comprising a support, selected from the group of metal oxides, capable of containing hydroxyl functions, on which a group of the formula (1) is grafted : -M (OR) n, where M is a selected element of scandium, zirconium, hafnium, niobium, tantalum, rare earth metals and actinides, R is "an organic group and n is an integer greater than or equal to 1, in the presence of ^ a protic compound, as a catalyst.

2. Process, according to claim 1, characterized in that a composition is used, whose support is selected from silica, alumina, zirconium oxide, cerium oxide, titanium oxide and thorium oxide, or their combinations or mixtures, as a catalyst .

3. Process, according to claims 1 or 2, characterized in that a composition comprising a support is used, on which the above-mentioned group is grafted on formula (1), where M is yttrium, lanthanum, samarium or neodymium, as a catalyst. ~

4. Process, according to one of the preceding claims, characterized in that a composition comprising a support is used, on which the aforementioned group of the formula (1) is grafted, wherein R is an alkyl group, linear or branched, saturated or unsaturated, an aryl group, an aralkylp group or an alkaryl group, as a catalyst.

5. Process according to one of the preceding claims, characterized in that a composition comprising a support is attached, which is an oxide from which the free or adsorbed water has been removed, as a catalyst.

6. Process according to one of the preceding claims, characterized in that the oxygenated rings are alkyl oxides, cyclic esters or cyclic carbonates.

7. Process, according to one of the preceding claims, characterized in that the polymerization takes place in a solvent medium.

8. Process, according to one of the preceding claims, characterized in that a protic compound of carboxylic acids, alcohols, thiols, glycols and polyols is selected.

9. Process, according to one of the preceding claims, characterized in that the oxygenated ring is an alkyl oxide and that a composition whose support is alumina is used.

The process according to claim 9, characterized in that the oxygenated ring is ethylene oxide or propylene oxide.

11. Process, according to one of the preceding claims, characterized in that the oxygenated ring is a cyclic ester and that a composition whose support is silica is used.

12. Process, according to one of the preceding claims, characterized in that products containing an oxygenated ring are copolymerized, with each other or with C02.