MXPA01006063A - Carboxylates in catalytic hydrolysis of alkylene oxides - Google Patents

Abstract

The present invention relates to a process for the preparation of alkylene glycols by reacting an alkylene oxide with water in the presence of a catalytic composition including a polycarboxylic acid derivative, having in its chain molecule one or more carboxyl groups and one or more carboxylate groups, the individual carboxyl and/or carboxylate groups being separated from each other in the chain molecule by a separating group consisting of at least one atom. Preferably the polycarboxylic acid derivative is immobilised on a solid support.

Description

CARBOXYLATES IN THE CATALYTIC HYDROLYSIS OF ALKYLENE OXIDES The present invention describes a process for the preparation of alkylene glycols by the reaction of an alkylene oxide with water in the presence of a catalytic composition. Background of the Invention Alkylene glycols, in particular monoalkylene glycols, are of established commercial interest. For example, monoalkylene glycols are used as solvents and as base materials in the production of polyalkylene terephthalate, for example, for fibers or bottles. The production of alkylene glycols by liquid phase hydrolysis of alkylene oxide is known. Hydrolysis is carried out without a catalyst by the addition of a large excess of water, for example, up to 20 to 25 moles of water per mole of alkylene oxide or is carried out with a smaller excess of water in a catalytic system, it is considered that the reaction is a nucleophilic substitution reaction, by virtue of which occurs the opening of the ring of oxide of Ref: 130533 alkylene and water acts as the nucleophile. Because the monoalkylene glycol formed in a primary manner acts as a nucleophile, per regia, a mixture of monoalkylene glycol, dialkylene glycol and higher alkylene glycols is formed. To increase the selectivity to monoalkylene glycol, it is necessary to suppress the secondary reaction between the primary product and the alkylene oxide, which competes with the hydrolysis of the alkylene oxide. An effective means to suppress the side reaction is to increase the relative amount of water present in the reaction mixture. Although this measure improves the selectivity towards monoalkylene glycol production, it creates a problem since it is necessary to extract large quantities of water to recover the product. Considerable efforts have been made to find an alternative measure designed to increase the selectivity of the reaction without having to use a large excess of water. In general, these efforts have been focused on the selection of more active hydrolysis catalysts and several catalysts have been discovered.

Both acidic and alkaline hydrolysis catalysts have been investigated, whereby the use of acidic catalysts may improve the reaction regime without significantly affecting the selectivity, while using alkaline catalysts, generally lower selectivities are obtained with respect to the monoalkylene glycol. It is known that certain anions, for example bicarbonate (hydrogen carbonate, bisulfite (hydrogen sulfide), formate and molybdate), have good catalytic activity in terms of conversion of alkylene oxide and selectivity to monoalkylene glycol, however, when the salts are used of these anions as the catalyst in a homogeneous system, the processing of the reaction product by distillation will present a problem because the salts are deficiently soluble in the glycol and will tend to make it semi-solid. The quaternary ammonium salts remain soluble in the glycol reaction product High conversions, good selectivity and a low water / alkylene oxide ratio can be obtained with the process, described in EP-A 0 156 449 and EP-A-O 160 330 (both of Union Carbide). According to these documents, the hydrolysis of alkylene oxides is carried out in the presence of a material containing anion metalate to improve the s electivity, preferably a solid having electropositive complex formation sites, which exhibit affinity for the metallate anions. Said solid is preferably an anionic permutation resin, in particular a copolymer of styrene-divinylbenzene. The electropositive complex formation sites are in particular quaternary ammonium, protonated tertiary amine or quaternary phosphonium. Metalate anions are specified as anions molybdate, tungstate, metavanadate, pyrovanadate of hydrogen and pyrovanadate anions. A complication of this process is that the glycol-containing product stream also comprises an essential amount of metallate anions, displaced from the electropositive complex formation sites of the sodium metalate anion-containing material. To reduce the amount of metallate anions in the alkylene glycol product stream, this stream is contacted with a solid having electropositive complex formation sites associated with anions that are replaced by said metallate anions. Patent Q 95/20559 (Shell) describes a process for the preparation of alkylene glycols, in which an alkylene oxide is reacted with water in the presence of a catalyst composition comprising a solid material having one more electropositive sites. which are coordinated with one or more anions other than metalato or halogen anions eg bicarbonate, bisulfite and carboxylate, with the proviso that when the solid material is an anionic permutation resin of the quaternary ammonium type and the anion is bicarbonate, it is performs the process in the essential absence of carbon dioxide. According to this document, the presence of carbon dioxide in the feed for the catalytic elect of the permutated resins with bicarbonate of the quaternary ammonium type is detrimental. A disadvantage shared by conventional anionic permutation resins is their limited tolerance to heat. In the practice of the alkylene oxide hydrolysis process according to WO 95/20559 with conventional organic permutation catalyst compositions of quaternary ammonium ion, it has been found that under severe reaction conditions of alkylene oxide hydrolysis (high temperature and / or prolonged service), the catalytic activity (selectivity and / or conversion) of the conventional resin-based catalysts tends to deteriorate. Furthermore, under these reaction conditions, it has been found that these catalysts undergo dilation. EP-A-226 799 discloses a method for the preparation of ethylene glycol or propylene glycol by hydration of the respective oxide, in the presence of catalysts of double composition consisting of a monobasic or polybasic carboxylic acid and a metal or ammonium salt of such carboxylic acid. Brief description of the invention The present invention relates to a process for the preparation of alkylene glycols by the reaction of an alkylene oxide with water in the presence of a catalytic composition including a polycarboxylic acid derivative having in its chain molecule flax or more. carboxyl groups and one or more carboxylate groups, which are separated from each other in the molecule by a separation group consisting of at least one atom. Preferably the number of carboxylic groups in the molecule is at least equal to the number of carboxylate groups. In a preferred form of the present invention, the polycarboxylic acid derivative as defined above is immobilized on a solid base. Solid catalysts are new which include such immobilized polycarboxylic acid derivatives. DETAILED DESCRIPTION OF THE INVENTION The carboxylate groups can be metal salts such as alkali metal and alkaline earth metal salts or ammonium salts. Preferably, the carboxylates are alkali metal salts, more preferably sodium salts. The separation group may comprise several atoms, which may then be arranged in a linear or ratified chain or in a ring. Preferably, the separation group consists of a single carbon atom.

Examples of dicarboxylic acid derivatives according to the invention are monosodium salts of malonic acid, succinic acid, adipic acid, tartaric acid, maleic acid, terephthalic acid, malic acid, suberic acid, italic acid, isophthalic acid, quinolinic acid (Acid 2). , 3-dicarboxylic pyridine), isoquinomeric acid (2,5-pyridine dicarboxylic acid), dipicolinic acid (2,6-pyridine dicarboxylic acid), quinomeronic acid (3,4-pyridine dicarboxylic acid), dinicotithinic acid (3,5-pyridine dicarboxylic acid), cyclohexane-1,2-dicarboxylic acid (3,4,5,6-tatrahydrophthalic acid) and isomers, cyclohexane-1,2-dicarboxylic acid (hexahydrophthalic acid) and isomers, cyclohexane-1, dicarboxylic acid, thiophene-2 acid, 5-dicarboxylic acid, chelidonic acid (4-oxo-4H-pyran-2,6-dicarboxylic acid, or thiophene-3,4-dicarboxylic acid), etc. Examples of tricarboxylic acid derivatives according to the invention are the monosodium salts of citric acid, trimellitic acid (1,2-benzene tricarboxylic acid) and trimesic acid (1,3-benzene tricarboxylic acid).

Examples of tet racarboxylic acid derivative according to the invention are the monosodium and disodium salt of pyromellitic acid (1, 2, 4, 5-benzene tet racarboxylic acid). As such, the polycarboxylic acid derivatives as defined herein are effective as hydrolysis catalysts of alkylene oxide in a homogeneous liquid reaction system. However, a particular advantage of these polycarboxylic acid derivatives arises when they are used in a heterogeneous reaction system, in which they are immobilized on a solid base, especially but not exclusively on a solid material having electropositive sites such as it is defined in WO 95/20559. In particular, when the solid base is a strongly basic anionic permutation resin, whose anion is exchanged with a polycarboxylic acid derivative according to the present invention, a catalytic composition is formed which is stable and retains its selectivity and stability under severe reaction, being more resistant to dilation. Any of a large number of ion exchange resins (RPI) can be used as the solid base, in particular ionic-strongly basic (anionic) permutation resins, in which the basic groups are quaternary ammonium or quaternary phosphonium. Ion-permutation resins based on vinylpyridine, polysiloxanes as well as other solid bases having electropositive complex formation sites of inorganic nature, such as carbon, silica, silica-alumina, zeolites, glass and clays such as hydrotalcite can be used as a solid base. . In addition only the solid base can be used immobilized macrocycles forming complexes such as crown ethers, etc.

The anionic permutation resins which are suitable for use in the present process are known per se and many are commercially available, for example, those sold under the trademarks AMBERJET 4200, AMBERLITE 400, IRA 404, LEWATIT M 500WSA, DOWEX 1 x 8, DOWEX MEA-1 (all of which are products based on polystyrene, degraded with divinylbenzene and REILLEX HPO (based on polyvinyl pyridine, degraded with divinylbenzene.) Immobilized crown ethers prepared on request, on and in different solid base materials such such as polystyrenes, acrylates and silicas, are currently distributed under the SuperLig brand by 1BC Advanced Technologies Inc. American Fork, Utah, USA The carboxylic acid derivative according to the invention can be immobilized on the solid base, by adding it in aqueous solution to a suspension of said base, which can be adapted or not in a preparation stage, for example, when the solid base is an anionic permutation resin, the immobilization can be carried out in a single step by mixing the resin with the catalyst in aqueous medium, followed by washing with water or, otherwise, in two steps by first converting the resin to its hydroxyl form with a hydroxide such as aqueous sodium hydroxide and then adding to the catalyst. The alkylene oxides used as the invention have their starting material in the process of the conventional invention, that is, they are compounds that have a vicinal oxide (epoxy) group in their molecules. Particularly suitable are the alkylene oxides of the general formula: wherein R 1 to R 4 independently represent an optionally substituted alkyl atom having from 1 to 6 carbon atoms. Any alkyl group, represented by R 1, R 2, R 3 and / or R 4 preferably have from 1 to 3 carbon atoms. As substituents, inactive moieties such as hydroxy groups may be present. Preferably, R1, R2 and R3 represent hydrogen atoms and R4 represents an unsubstituted C1-C3 alkyl group and, more preferably, R1, R2, R3 and R4 represent all hydrogen atoms. Thus, suitable examples of alkylene oxide include ethylene oxide, propylene oxide, 1,2-epoxybutane, 2,3-epoxybutane and glycidol. Ethylene oxide and propylene oxide are of particular commercial importance. As mentioned above, it is advantageous to carry out the hydrolysis of the alkylene oxides, without using excessive amounts of water. In the process according to the present invention, water quantities in the scale of 1 to 15 mol per mol of alkylene oxide are quite appropriate, quantities in the scale of 1 to 6 on the same basis are preferred. In the process of the invention, high selectivities are often achieved with respect to the monoalkylene glycol, when only 4 or 5 moles of water are supplied per mole of alkylene oxide. The process of the invention can be carried out in a batch operation. However, in particular for large-scale forms, it is preferred to perform the process continuously. Such a continuous process can be performed in a fixed bed reactor, operated in upflow or in downflow. Downflow operation is preferred. The reactor can be maintained under isothermal, adiabatic or hybrid conditions. The isothermal reactors are generally roof and tube reactors, mainly of the multi-tube type, in which the tubes contain the catalyst and the refrigerant passes out of the tubes. The adiabatic reactors are not cooled and the product stream leaving them can be cooled in a separate thermal exchanger. Under certain circumstances the catalytic conversion of ethylene oxide may remain incomplete, a situation in which the remainder of the latter can be thermally hydrolyzed in the reactor dead space below the catalyst bed. Since this thermal hydrolysis is less specific towards MEG, it is recommended to reduce the retention of liquid in the reactor. This can be accomplished by filling the reactor outlet part with internal elements or inert filler to reduce its volume and / or by adding an inert gas such as nitrogen to the reactor feed mixture and operating therein under so-called flow conditions by drip To obtain adequate values of time performance, it is recommended to carry out the process under conditions of high temperature and pressure. Suitable reaction temperatures are generally in the range of 80 to 200 ° C, whereby temperatures on the scale of 90 to 150 ° C are preferred. The reaction pressure is generally selected on the scale of 200 to 3000, preferably 200 to 2000 kPa. For batch operations of the process, the reaction pressure is advantageously obtained by compression with an inert gas, such as nitrogen. If desired, mixtures of gases can be used, for example a mixture of carbon dioxide and nitrogen is advantageous under certain circumstances. To accommodate any expansion of the catalyst during operation, the volume of the reactor may advantageously be greater than the volume occupied by the catalyst for example from 10 to 70 volumes per cent greater. It will be understood that the catalyst according to the present invention can also be used in combination with other catalysts. In certain situations, particularly when operating in the continuous flow form, it has been found to be advantageous to subject at least part, such as 30-60% by weight, from the alkylene oxide feed stream to the partial thermal hydrolysis in the absence of catalyst, before completing the hydrolysis catalytically. It has been found that partial hydrolysis even in the absence of a catalyst is still sufficiently selective towards the monoalkylene glycol while, on the other hand, this measure is effective to save the catalyst. A problem that may occasionally arise in any process in which it is hydrolyzing to ethylene oxide, is the presence of small amounts of amines and / or phosphines as impurities in the product stream. When a strong anionic permutation resin is used basically as the solid base for the catalytic anion its basic groups are quaternary ammonium or quaternary phosphonium groups. It has been found that during operation, small amounts of amines or phosphines tend to leach from the resin into the product stream. In addition, the amines in the product stream can originate from the corrosion inhibitors, which can be added to the water used in the process. Although the amounts of such amine or phosphine contaminants that reach the final product are generally small, they can affect the quality of the final product so that it may be advisable to keep them below the level of detection. For example, triethylamine (TMA) and / or dimethylamine (DMA) can reach the final product in an amount of up to 10 ppm, while the fishy odor of TMA can be detected in an amount as low as 1 ppb. It has been found that an effective measure for extracting the sands and / or phosphines that may be present in the product stream from any process in which ethylene oxide is hydrolyzed, including the process of the present invention, is to use a protective bed containing a strongly acidic ion permutation resin that captures or phosphines. The strongly acidic ion exchange permutation resins are of the sulphonic type. Commercially available examples are those known by the trademarks AMBERLYS 15, AmBERJET 1500H, AMBERJET 1200H. DOWEX MSC-1, DOWEX 50W, DIANON SKIB, LEWATIT VP OC 1812, LEWATIT S 100 MB and LEWATIT S 100 Gl. These highly acidic ion exchange resins are available in the H + form and in the salt form, such as the Na + form. When the H + form of the strongly acid resin is used in the protective bed, the product stream becomes acidic after passing through 61. The use of a strongly acidic ion permutation resin mixture in its H + form and the form of salt has the advantage that the pH of the product stream remains close to the neutral value. An additional advantage of the strongly basic protective bed is that any remaining alkylene oxide that may still be present in the product stream is hydrolyzed to monoalkylene glycol, although with a lower selectivity towards the monoalkylene glycol. To accommodate the depletion of strongly acidic ion exchange resin during operation, it is advantageous to operate the protective bed in two or more separate containers. The strongly acidic exhausted ion permutation resin can be regenerated by treatment with an acid which is stronger than the sulphonic acid groups in the resin matrix, such as HCl and H2SO4. The hot sulfuric acid has been shown to be effective with a normality of 0.1-2. The following examples will illustrate the invention Examples I. Experiments 1-12, batch hydrolysis in homogeneous catalyst system. The following samples of carboxylic acid and sodium carboxylates were classified for catalytic activity in a hydrolysis reaction of ethylene oxide-batch: Dicarboxylic acids and carboxylates: - oxalic acid HOOC-COOH and its mono- and disodium salt. - malonic acid HOOC-CH2-COOH and its monosodium salt. succinic acid HOOC-CH2-CH2 and its mono-and disodium salt. - tartaric acid HOC-CH (OH) -CH (OH) -COOH and its mono- and disodium salt. - mono- and disodium salt of maleic acid HOOC-CH = CH-COOH; adipic acid (HOOC- (CH2) -COOH) and its monosodium salt. - terephthalic acid p-COOH-C6H4 -COOH and its mono- and disodium salt. Tricarboxylic acids and carboxylates: - citric acid HOOC-CH2-C (OH) (COOH) -CH2-OOCH, its mono- and dibasic salt. - trimethylic acid 1, 2, 4-C6H3 (COOH) 3 and its mono- and disodium salt. Tet racarboxylic acid and carboxylates: - Pyromelitic acid 1,2,4,5-C6H2 (COOH) 4 and its mono-, di- and trisodium salt. A key car with a capacity of 250 ml was loaded with 30 ml of polycarboxylic acid derivative-or the comparative sodium bicarbonate and 5.55 mol (100 grams) of water. Some of the carboxylic acid derivatives were purchased as hydrates and used as such. However, the amount of water introduced by these hydrates (maximum 210 millimoles) was considered insignificant and no adjustment was made to the water intake. The gas cap was purged 3 times with nitrogen and an initial pressure of 1000 kPa was used. The mixture was heated to 100 ° C. Ethylene oxide (11 grams, 1 mole) was slowly added under stirring at 500 rpm. S-e kept the reaction mixture under continuous stirring for 6 hours at 100 ° C. the end of the batch sample was taken for GLC analysis.

Table 1 presents a summary of the results of batch catalytic hydrolysis experiments of ethylene oxide, in terms of selectivity to MEC, using homogeneous catalysts (carboxylic acids and sodium carboxylates), as well as the results of the reference experiments (without catalyst and NaHCO3). Table 1 * Selectivity towards MEG (mole%) = 100 x MEG / (MFG + 2DEG 3TEG), measured at > 99.5% conversion of ethylene oxide The results indicate that, in all cases, the polycarboxylic acids have a performance only slightly better than the uncatalyzed thermal reaction (70.8 - 77.0 vs. Selectivity 67.8% to MEG).

Except for oxalic acid (not according to the invention), a significant improvement in MEG selectivity (up to 80.3-85.4%) was achieved. When the mono-sodium salts of a dicarboxylic acid were used as a catalyst; however, when both carboxylic acid groups of a dicarboxylic acid are converted to carboxylate groups, the selectivity becomes lower (48.9-66.0%). A similar behavior was observed for tricarboxylic acids: an ideal selectivity for the mono-sodium salts (84-85%) and a lower selectivity for the trisodium analogues. Likewise, the disodium carboxylates of the tricarboxylic acids show a decrease in the selectivity (although less pronounced) when compared with the corresponding monosodium salts (64.8 / 76.7 vs. 85%). Tetracarboxylic acid (piromethyl acid) behaves similarly; in this case, both mono- and disodic carboxylates have the ideal selectivity yield (83.9 / 84.6%). II. Experiments 13-17, batch hydrolysis in heterogeneous catalytic system We used strongly basic ion exchange resins of the quaternary ammonium type: AHBERJET 4200, a resin based on mono-di-spersado / divinylbenzene degraded polystyrene, ex Rohm and Hass, chloride form, permutation capacity 1.4 milliequivalents - IRA 404, a resin based on poly-dispersed polystyrene degraded / divinylbenzene, ex Rohm and Hass, chloride form, permutation capacity 1,3-milliequivalents / ml. The resin was treated in the following manner to immobilize the carboxylic acid derivative: - 150 ml of wet resin was combined in a glass tube filled with water (60 x 2.5 cm); the chloride was permuted by treatment with sodium bicarbonate (reference), monosodium citrate (according to the invention) or trisodium citrate (reference), in each case in aqueous solution (10 molar excess, in 2500 grams of water) for about 5 hours. hours (liquid space velocity per hour: 4 liters / hour); - the permuted resin was washed with 1200 ml of water for 2 hours (space velocity of liquid per hour 4 liters / hcra); - by this procedure most (> 98%) of the chlorine anions contained in the resin were permuted by the desired anion. A 250 ml autoclave was filled with the catalyst (30 mmol) and water (100 grams, 5.55 mol). The gas cap was purged 3 times with nitrogen and an initial pressure of 1000 kPa was used. The mixture 5 It was heated to 100 ° C. Ethylene oxide (44 g, 1 mol) was slowly added under stirring (500 rpm). The reaction mixture was kept under continuous stirring for 6 hours at 100 ° C. The end of the batch manner was taken for GLC analysis. Table 2 contains the results (conversion data of ethylene oxide and MEG selectivity). Table 2 * Conversion OE (%) = 100% (MEG + 2DEG + 3TEG) / (EO + MEG + 2DEG + 3TEG) **: Selectivity towards MEG (%) = 100 x MEG / (MEG + 2DEG + 3TEG). The results contained in Table 2 indicate that in a similar way to the observations in a homogeneous catalytic system, also in a heterogeneous system the partial salt of the polycarboxylic acid in a satisfactorily selective catalyst, while the complete salt is not. III. Experiments 19-20, catalyst stability test. The thermal stability of an AMBERJET 4200 / carboxylate catalyst was evaluated and compared to the thermal stability of AMBERJET 4200 / bicarbonate. The thermal stability was tested by placing 20 ml of the catalyst in a Hoke tube 65 cm long, 0.5 inch wide, fitted with a heating jacket using a heating oil system. Water was pumped with an HPLC pump, with a liquid space velocity per hour of 1 liter / hour on the catalyst bed at 150 ° C and a pressure of 1000 kPa for 48 hours. Then, the catalyst sample was withdrawn from the reactor. The strongly basic capacity (quaternary ammonium groups), the weakly basic capacity (tertiary amine groups) and the total anion capacity (the sum of the two previous capacities) in fresh and used catalyst were determined by titration, and the% was noted. of difference (change during use). The results are contained in Table 3.

Table 3 i- C \ J i-O LO O M These results indicate that, in this severe accelerated stability test, the IER / monoanion citrate catalyst is 2 times more stable than the corresponding bicarbonate catalyst. IV. Experiment 21, continuous hydrolysis in a heterogeneous catalytic system. The AMBERJET 4200 / mono-anion citrate catalyst was used in this test, in which the parameters of the process varied (water molar ratio: 0E between 5.0 and 18.9, liquid space velocity per hour between 0.81-95 and maximum bed temperature between 95- 112 ° C). The samples were taken periodically. The results are contained in table 4 Table 4 *: Conversion OE (mol%) = 100 x (MEG + 2DEG + 3TEG) / (OE + MEG.}. 2DEG.}. 3TEG ** selectivity towards MEG (% mol) = 100 x MEG / (MEG + 2DEG + 3 TEG). V. Experiments 22 and 23, continuous hydrolysis of ethylene oxide. The AMBERJET 4200 catalyst / mono-anion citrate was used in a continuous fixed-bed experiment. The long-term performance was compared with that of AMBERJET 4200 / bicarbonate under exactly identical process conditions. The experiments were performed in a single pass mode. The 24 cm long reactor consisted of a 20 mm wide glass tube (internal diameter), in a 34 mm wide stainless steel tube. Between the glass reactor tube and the stainless steel outer tube, a Teflon (PTFE) layer was used as an insulator. An electric heating system was used in the external stainless steel tube to compensate for heat losses; The temperature set point for this heating device was placed at the water / OE feed temperature of the reactor. The reactor was charged with 60 ml of catalyst. The water was preheated to achieve the desired temperature of inlet to the reactor before mixing with the ethylene oxide, the temperature of the feed was measured using a thermal pair placed in the upper part of the reactor and the exit temperature was measured using a couple thermally below the catalyst bed at the reactor outlet. Table 5.1 contains the process conditions during these experiments Tables 5.2 and 5.3 show the results of this comparative experiment, showing that the AMBERJET 4200 / citrate catalyst has a significantly increased under the process conditions applied when compared to the corresponding bicarbonate catalyst. Table 5.2 Catalyst AMBERJET 4200 / bicarbonate Table 5.3 Catalyst AMBERJET 4200 / citrate It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (10)

1. CLAIMS Having described the foregoing, the claim contained in the following claims is claimed as property: 1. A process for the preparation of alkylene glycols by the reaction of an alkylene oxide with water in the presence of a catalyst composition including a polycarboxylic acid derivative , which has in its chain molecule one or more carboxyl groups and one or more carboxylate groups are separated from each other in the molecule by a separation group consisting of at least one atom.
2. 2. A process according to claim 1, characterized in that the separation group consists of a single carbon atom.
3. 3. A process according to claim 1 or 2, characterized in that the polycarboxylic acid derivative is a citric acid derivative.
4. 4. A process according to claim 3, characterized in that the citric acid derivative is the mono-anion of citric acid.
5. 5. A process according to any of claims 1 to 4, characterized in that the carboxylic acid derivative is immobilized on a solid base.
6. 6. A process according to claim 5, characterized in that the solid base is one that has electropositive sites.
7. 7. A process according to claim 6, characterized in that the solid base is an anionic permutation resin of the quaternary ammonium or quaternary phosphonium type.
8. 8. A process according to claim 5, characterized in that the solid base is a clay.
9. 9. A process according to claim 5, characterized in that the solid base comprises an immobilized macrocycle.
10. 10. a catalyst composition suitable for the preparation of alkylene glycols by the reaction of an alkylene oxide with water, including a polycarboxylic acid derivative as defined in claims 1-4, which is immobilized on a solid base such as was defined in any of claims 5-9.