EP2350041A1

EP2350041A1 - Method and catalysts for producing cyclic carbonates

Info

Publication number: EP2350041A1
Application number: EP09783934A
Authority: EP
Inventors: Roman Prochazka; Veronika Wloka
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2008-10-17
Filing date: 2009-10-12
Publication date: 2011-08-03
Also published as: WO2010043581A1; KR20110070915A; US20110201828A1; JP2012505853A; CN102186837A

Abstract

The invention relates to a method for producing cyclic carbonates by reacting a multivalent alcohol with a dialkyl carbonate in the presence of a heterogeneous catalyst, characterized in that the heterogeneous catalyst is a basic mixed oxide or a basic oxide applied to a carrier.

Description

METHOD AND CATALYSTS FOR THE PRODUCTION OF CYCLIC

CARBONATES

description

The invention relates to a process for preparing cyclic carbonates by reacting a polyhydric alcohol with a dialkyl carbonate in the presence of a heterogeneous catalyst, which is characterized in that the heterogeneous catalyst is a basic mixed oxide or supported on a carrier oxide.

Cyclic carbonates, especially glycerin carbonate, are important as solvents, additives for cosmetics and detergents. They are also used for the production of epoxy resins, polycarbonates and polyurethanes.

Cyclic carbonates such as glycerol carbonate can be prepared by reacting polyhydric alcohols with dialkyl carbonate in the presence of a catalyst.

The use of homogeneous and heterogeneous catalysts is known.

According to US 5 091 543, alkylammonium salts or pyridinium salts are used as homogeneous catalysts.

EP-A 739 888 discloses the use of zeolites as catalysts. The reaction mixture of glycerol and dialkyl carbonate contains the zeolites as heterogeneous catalysts.

DE-A 10 2005 060 732 describes the use of basic catalysts. The basic catalysts are in particular alkali and / or alkaline earth salts, e.g. to the corresponding oxides, hydroxides or chlorides. Preference is given to the use of mixtures of chlorides and oxides. The listed alkali and alkaline earth chlorides, in particular the lithium chloride, are at least partially water-soluble.

Homogeneous catalysts generally have the disadvantage that they are difficult to separate from the product mixture. On the other hand, heterogeneous catalysts can easily be recovered and reused.

For the above reaction, therefore, heterogeneous catalysts are desired which cause the highest possible yield and selectivity with the shortest possible reaction time. Furthermore, the heterogeneous catalysts should contain as few constituents as possible which dissolve out of the catalyst under the reaction conditions (leaking) and thus introduce unwanted impurities into the product mixture. In particular, in the workup of, for example, glycerol carbonate, the presence of such Impurities are critical and cause in the distillation of glycerol carbonate decomposition to explosive glycidol. In addition, the required amounts of catalyst should be as low as possible.

The object of the present invention was therefore a process for the preparation of cyclic carbonates in which such catalysts are used.

Accordingly, the method defined above was found.

In the process according to the invention, cyclic carbonates are prepared by reacting a polyhydric alcohol with a dialkyl carbonate.

Illustrated by the example of glycerol and dimethyl carbonate, the reaction proceeds according to the following reaction equation:

To the starting materials

Suitable polyhydric alcohols are chemical compounds having at least two hydroxyl groups, which form a ring system by reaction with dialkyl carbonates.

Preferred polyhydric alcohols are aliphatic compounds having at least two hydroxyl groups which are relative to each other in 1, 2 position, 1, 3 position or 1, 4 position. In 1, 2 position are the two hydroxyl groups on adjacent carbon atoms and in the above reaction, a 5-ring is formed; in 1, 3 position corresponding to a 6-ring and at a 1, 4 position forms a 7-ring. It is preferably a 1, 2 position, so that forms a 5-ring.

The polyhydric alcohol is preferably an aliphatic diol or triol in which two hydroxyl groups are in the 1,2-position. The polyhydric alcohol preferably contains no further functional groups and in particular has a molecular weight of less than 300 g / mol.

Particularly preferred is glycerol. Suitable dialkyl carbonate z. B. Carbonates with C1 to C10 alkyl groups; Dimethyl carbonate or diethyl carbonate may be mentioned in particular.

Particularly preferred is dimethyl carbonate.

To the heterogeneous catalyst

According to the invention, a heterogeneous catalyst is used. The heterogeneous catalyst forms its own phase under the reaction conditions. In the present case, the heterogeneous catalyst is solid, while the starting materials are liquid or gaseous.

As the heterogeneous catalyst, a basic mixed oxide or a supported basic oxide is used.

The mixed oxide is an oxide of at least two different elements. The mixed oxide is basic when it leads to a pH increase in water.

The mixed oxides are preferably mixtures of at least two oxides selected from oxides of metals of the main groups I a, II a, III a, and IV a of the periodic table, the subgroups II b, III b and IV b of the Periodic Table, and the lanthanides. The choice of oxides is made on the proviso that the resulting mixed oxide is basic.

For this purpose, the mixed oxide preferably contains at least one oxide from the main group IIa; However, it is also possible basic mixed oxides without the use of an oxide from the group Il a is possible, for example. a mixed oxide of zinc oxide (ZnO) and aluminum oxide (Al 2 O 3).

Particularly preferred are mixed oxides which are composed of oxides of metals of groups I a, III a, III a, I b and II b of the Periodic Table, wherein at least one oxide of a metal of the main group Il a is contained in the mixed oxide.

The mixed oxide may contain more than two metal oxides, but a large number of different metal oxides in the mixed oxide is not necessary. Already suitable are mixed oxides of two or three metal oxides, in particular of two metal oxides.

In a preferred embodiment, the heterogeneous catalyst is a base oxide supported on a support. , The support may be of any inorganic material such as zeolites, carbon, polymers, alumina, titania, zirconia, silica, magnesia, silica-aluminas, silica-titania, silica-zirconia, titania-zirconia, magnesia-alumina ,

The support is preferably an inorganic support, in particular a metal oxide or a nonmetal oxide.

In particular, it is a carrier of zirconium oxide, silica, alumina, titania or mixtures thereof.

Very particular preference is zirconium oxide.

At least one basic oxide is applied to the support. It may be z. B. a metal oxide of metals of the main groups I a, II a, III a, and IV a of the Periodic Table, the subgroups II b, III b and IV b of the Periodic Table, as well as the lanthanides act.

It is also possible for a plurality of oxides, in particular the mixed oxides listed above, to be applied to the support.

Preferably, at least one metal oxide of a metal of the main group I a or II a, the subgroup III b or the lanthanides is applied to the support.

It is particularly preferably an alkaline earth oxide (main group IIa), e.g. CaO, BaO or MgO.

Very particular preference is CaO.

In a very particularly preferred embodiment, the heterogeneous catalyst is a supported catalyst of a metal oxide, in particular of ZrO.sub.2, TiO.sub.2, SiO.sub.2 or Al.sub.2O.sub.3, more preferably ZrO.sub.2, to which at least one further metal oxide, in particular an alkaline earth oxide, e.g. CaO, BaO or MgO is applied. In particular, it is a base supported catalyst with a carrier of zirconium dioxide, is applied to the CaO.

The applied metal oxide can be located for the most part on the surface of the support, but the metal oxide or the corresponding metal cations can also be distributed substantially uniformly in the support; The person skilled in the art also speaks here of a doping of the oxidic support with the relevant metal cations. The mode of application or distribution in or on the carrier is responsible for the effect of Catalyst of minor importance and depends only on the method of preparation and / or the porosity of the carrier.

The content of metal oxide applied in the supported catalyst preferably corresponds to an amount of from 0.1 to 25% by weight, more preferably from 0.5 to 10% by weight, of alkaline earth cations, based on the total supported catalyst.

The catalysts may additionally be modified, e.g. by further doping with other alkali metals, alkaline earth metals, chalcogens or halogens. However, they preferably contain no or at most small constituents of compounds which can leach out of the heterogeneous catalyst under the reaction conditions and thus lead to the problem of "leaking." In particular, therefore, a content of water-soluble alkali metal salts such as LiCl is as low as possible the content of water-soluble alkali metal salts is less than 0.5 part by weight, more preferably less than 0.1 part by weight per 100 parts by weight of heterogeneous catalyst.

The heterogeneous catalysts can be used in the form of powder or preferably in the form of shaped articles such as extrudates, SpNt, rings, hollow cylinders, spheres or tablets having a characteristic diameter of 0.1 to 5 mm, preferably 1 to 3 mm. The characteristic diameter results from six times the quotient of the volume of the shaped body and of the geometric shaped body surface. Binders can be added to the catalyst for the production of moldings.

The catalysts may have pores, e.g. B. with a pore volume 0.05 to 1, 0 ml / g.

For the preparation of heterogeneous catalysts

The basic mixed oxides can be prepared by customary methods known to the person skilled in the art.

To prepare the basic mixed oxides, the desired metal salts can first be dissolved in water and then precipitated with a suitable precipitating agent (eg aqueous ammonia solution, solutions of alkali metal carbonates or bicarbonates, such as sodium carbonate, urotropin, etc.). Thereafter, the resulting solid can be washed and dried, for. B. also by spray drying. Finally, the product obtained directly or shortly before use later at temperatures of 200 to 1200, in particular 400 to 600 ⁰ C, for example, under air or nitrogen, are activated. The preparation of the basic supported catalyst can also be carried out by customary methods known to the person skilled in the art.

Again, preferably an aqueous solution of the desired metal salts is prepared first. The carrier is then treated with this solution. The amount of solution can be such that it is completely or almost completely absorbed by the carrier (impregnation on water absorption). However, the catalyst can also be dispersed in the aqueous solution and then separated from the solution, for. B. by filtration. Subsequently, in turn, an activation at high temperatures, as described above, take place.

To the procedure

The starting materials can be reacted in the liquid or gas phase in the presence of the heterogeneous catalyst.

In the above starting materials, especially the glycerol and dimethyl carbonate, the reaction preferably takes place in the liquid phase.

The polyhydric alcohol or the dialkyl carbonate can be used in excess. In a preferred embodiment, the dialkyl carbonate, preferably dimethyl carbonate, is used in excess, e.g. can be used on 1 mol of polyhydric alcohol (glycerol) 1, 1 to 10 mol, in particular 1, 5 to 8 mol or 1, 5 to 5 mol of dialkyl carbonate.

The reaction can be carried out at atmospheric pressure, reduced pressure or overpressure. Preferably, it is carried out at atmospheric pressure.

The reaction is preferably carried out at elevated temperature, e.g. B. at temperatures of 30 to 100 ⁰ C, in particular 50 to 90 ⁰ C.

The reaction can be carried out discontinuously (batchwise, ie with presentation of the entire amount of all starting materials), semi-continuously (metered addition of a portion of the starting materials during the reaction) or continuously. In the continuous operation, both the polyhydric alcohol and the dialkyl carbonate are preferably continuously supplied. The heterogeneous catalyst is preferably used in amounts of 0.1 to 10 parts by weight, particularly preferably 0.2 to 5 parts by weight, based on 100 parts by weight of polyhydric alcohol.

By the method according to the invention a high yield and selectivity of cyclic carbonate is achieved with short reaction times. The required amount of the heterogeneous catalyst is low.

The heterogeneous catalyst can in a simple manner, for. B. by filtration, separated from the product mixture, optionally worked up and recycled. On a content of soluble components in the heterogeneous catalyst, which lead to the problem of "leaking", can be dispensed with.

The heterogeneous catalyst also has a long service life. In a continuous procedure, a high yield and selectivity over a long time is maintained.

In a batchwise process, the catalyst can be used repeatedly; after the batch preparation of the cyclic carbonate, the catalyst can be separated from the product and used again for a new batch preparation; this can be done several times, z. B. be repeated up to 10 times with reuse of the same catalyst.

Examples:

A) Preparation of the catalysts

An overview of the catalysts produced is given in Table 1.

Example 1 :

10 l of water were placed in a precipitation vessel and then simultaneously a 20% strength aqueous Na 2 CO 3 solution and an aqueous solution of calcium nitrate and aluminum nitrate (134 kg solution containing 4.81 kg of CaO and 8.19 kg of Al 2 O 3) with stirring 8O ⁰ C and pH 5.5 precipitated. After adding a total of 190 kg of Na 2 CO 3 solution, the final pH was 7.8. The product was filtered, washed with water and dried at 100 ^° C. for 16 h. 19.06 kg of the dried product were kneaded with 10.69 l of water and 190 g of polyethylene oxide and extruded into 1.5 mm extrudates. The extrudates were dried for 16 h at 120 ⁰ C and finally calcined in air at 600 ⁰ C for 1 h. There were obtained 15.1 kg Stränglinge with a CaO content of 35% and an Al ₂ O ₃ content of 65%.

EXAMPLE 2 10 l of water were introduced into a precipitation vessel and then simultaneously a 20% strength aqueous Na 2 CC 3 solution and an aqueous solution of magnesium nitrate, zinc nitrate and aluminum nitrate (140 kg of solution containing 1.56 kg of MgO, 3.25 kg ZnO and AI2O3 8.19 kg) with stirring at 8O ⁰ C and pH 5.5 brought to precipitation. After addition of a total of 190 kg Na2CO3 solution, the final pH value was 7.8. the product is filtered de wur- , washed with water and dried for 16 h at 100 ° C. 18.62 kg of the dried product was kneaded with 4.8 l of water and extruded to 1, 5 mm extrudates. the extrudates were then dried for 16 h at 120 ⁰ C and finally calcined in air at 600 ° C. for 1 h to give 12.1 kg of rods with an MgO content of 11%, a ZnO content of 25% and an Abθ3 content of 64%.

Example 3:

150 kg of zirconium oxide (material D9-89, BASF) were kneaded with 16.65 kg of 70% Siles MSE 100 (from Wacker), 35 l of water and 1.5 kg of polyethylene oxide for 60 min. The material was then extruded to 1, 5 mm extrudates, which were dried on a belt calciner at 120 ⁰ C overnight and then calcined at 580 ⁰ C for 2 h. There were obtained 143.8 kg of white zirconia extrudates. Example 4:

120 g of zirconia extrudates from Example 3 were placed in a flask and a clear solution of 29.5 g of Ca (NOs) 2 ^* 4 H2O and 38 g of water was added. The material was well mixed several times, then dried at 120 ⁰ C for 16 h in air and finally calcined at a heating rate of 10 K / min at 500 ⁰ C for 2 h in air. There were obtained 123.6 g of white strand with a Ca content of 3.5%.

Example 5 200 g of zirconium oxide (material SZ 31108, Norpro) in the form of 3 mm extrudates were calcined for 5 h at 500 ° C. in air. The strands were placed in a flask and a clear solution of 93.74 g of Ca (NOs) 2 ^* 4 H2O and 80.4 g of water was added. The impregnated extrudates were then predried for 30 min at RT and for a further 30 min at 8O ⁰ C on a rotary evaporator. Then, the extrudates were carried out at 100 ⁰ C for 16 h air dried and finally h with a heating rate of 2 K / min at 500 ⁰ C for 16 calcined in air. There were obtained 226.9 g of beige strands with a 6.5% Ca content.

Example 6: 200 g of zirconium oxide (. Material SZ 31108, Norpro Fa) in the form of 3 mm extrudates were calcined for 5 h at 500 ⁰ C in air. The strands were placed in a flask and a clear solution of 155.44 g of Mg (NOs) 2 ^* 6 H2O and 80.4 g of water was added. The impregnated extrudates were then predried for 30 min at RT and for a further 30 min at 8O ⁰ C on a rotary evaporator. Then, the strand pieces were air-dried at 100 ° C for 16 hours and finally calcined at a heating rate of 2 K / min. At 500 ° C for 16 hours in air. There were obtained 206.4 g of white rods with a Mg content of 1.7%.

Example 7: 120 g of titanium oxide (. S material 150, Fa Finnti) in the form of 1, 5 mm extrudates were placed in a flask and a clear solution of 29.5 g of Ca (NO3) 2 ^* 4 H2O and 62 g of water were added , The material was well mixed several times, then dried at 120 ⁰ C for 16 h in air and finally calcined at a heating rate of 10 K / min at 500 ⁰ C for 2 h in air. There were obtained 124.2 g of white strands with a Ca content of 4.2%.

Example 8:

120 g of silica (1-10 D1 material, BASF) in the form of 1, 5 mm extrudates were placed in a flask and a clear solution of 29.5 g of Ca (NÜ3) 2 ^* 4 H2O, and 166 g water was added. The material was well mixed several times, then dried at 120 ° C for 16 h in air and finally with a heating rate of 10 K / min calcined at 500 ⁰ C for 2 h in air. There were obtained 124.5 g of white stranders with a Ca content of 4.2%.

EXAMPLE 9 120 g of alumina (material D10-10, BASF) 4 H2O and 144 g of water was added in the form of 1, 5 mm extrudates were placed in a flask and a clear solution of 29.5 g of Ca (NO3) 2 ^*. The material was well mixed several times, then dried at 120 ⁰ C for 16 h in air and finally calcined at a heating rate of 10 K / min at 500 ⁰ C for 2 h in air. There were obtained 123.8 g of white stranders with a Ca content of 3.3%.

Example 10:

2.6 kg of calcium carbonate were calcined at 800 ° C for 2 h and further processed under nitrogen. 1.4 kg of the resulting CaO powder were mixed with 42 g of magnesium stearate. The mixture was processed on a rotary tableting machine into 5 x 3 mm tablets with a pressing force of 25 kN. The tablets were finally calcined at 450 ^° C. in air for 2 h.

Example 11: 1.5 kg of MgO granules (Magnesia) were mixed with 45 g of magnesium stearate. The mixture was processed on a rotary tabletting machine into 3 x 3 mm tablets with a pressing force of 12.4 kN. The tablets were finally calcined at 450 ° C in air for 2 h.

B) Example of the preparation of glycerol carbonate

The experiment was carried out in Glasrühepparaturen with Wasserauskreiser under reflux.

Standard approach:

In a 4-necked flask equipped with a stirrer and a reflux condenser, 23 g (0.25 mol) of glycerol (anhydrous, pure,> 99%, Merck), 90 g (1 mol) of dimethyl carbonate (99%, Fa ACROS) and 0.6 g of catalyst (= 2.6 wt .-% relative to glycerol) placed in a catalyst basket. The reaction mixture was heated to 8O ⁰ C. The course of the reaction was monitored by GC (30m DB5 column). After the reaction was completed, the reaction mixture was cooled and the catalyst was separated. The low boilers were then distilled off in vacuo and the crude product obtained. Table 1

Test series with Mg, Ca and Ba catalysts

Catalysts 1 and 2 are mixed oxides according to the invention. Catalysts 4 to 9 are supported catalysts according to the invention, catalysts 10 and 11 are for comparison

Catalyst Leaching

In order to be able to compare the catalyst stability, experiments were carried out with the catalysts described in the application of Röhm GmbH (DE 10 2005 060 732) and the catalyst No. 4 described above. The catalysts from DE 10 2005 060 732 are dried or calcined mixtures of CaO and LiCl; in both cases a strong leaching was observed. In contrast, the catalyst 4 contains neither an alkali doping nor halides and has no significant leaching (Table 2).

Table 2:

Comparison of the catalyst leaching

Claims

claims

1. A process for the preparation of cyclic carbonates by reacting a polyhydric alcohol with a dialkyl carbonate in the presence of a heterogeneous catalyst, characterized in that it is in the heterogeneous

Catalyst is a basic mixed oxide or supported on a carrier oxide.

2. The method according to claim 1, characterized in that glycerol is reacted with a dialkyl carbonate to glycerol carbonate.

3. Process according to claim 1 or 2, characterized in that the dialkyl carbonate is dimethyl carbonate.

4. The method according to any one of claims 1 to 3, characterized in that it is the heterogeneous catalyst applied to a carrier base oxide.

A method according to claim 4, characterized in that the support is a support of zirconia, silica, alumina, titania or mixtures thereof.

6. The method according to claim 4 or 5, characterized in that it is the carrier is a carrier of zirconium oxide.

7. The method according to any one of claims 4 to 6, characterized in that it is the alkaline oxide is an alkaline earth metal oxide.

8. The method according to any one of claims 4 to 7, characterized in that it is the basic oxide is calcium oxide.

9. The method according to any one of claims 1 to 8, characterized in that the heterogeneous catalyst contains less than 0.1 parts by weight of water-soluble alkali metal salts per 100 parts by weight of heterogeneous catalyst.

10. The method according to any one of claims 1 to 9, characterized in that the heterogeneous catalyst in amounts of 0.1 to 10 parts by weight, based on 100 parts by weight of polyhydric alcohol is used.

1 1. Cyclic carbonates obtainable by a process according to any one of claims 1 to 10.

12. Use of the cyclic carbonates according to claim 1 1 as a solvent, as an additive in cosmetics, in cleaning agents or as starting materials for the production of epoxy resins, polycarbonates or polyurethanes.

13. Supported catalyst with a support of zirconium dioxide and a content of alkaline earth metal oxides.

14. Supported catalyst with a support of zirconium dioxide and a content of calzi- oxide

15. Supported catalyst according to claim 13 or 14, characterized in that the content of alkaline earth cements 0.1 to 25 wt.%, Based on the total supported catalyst.