EP0729389A1

EP0729389A1 - Magnetically separable catalysts

Info

Publication number: EP0729389A1
Application number: EP95900718A
Authority: EP
Inventors: Claudius Kormann; Thomas Wettling; Ekkehard Schwab; Jochem Henkelmann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1993-11-16
Filing date: 1994-11-11
Publication date: 1996-09-04
Also published as: US5929260A; JPH09504991A; WO1995013874A1; DE4339139A1

Abstract

Disclosed are catalysts based on: a) a magnetizable core which, b) can as needed be coated with a binder, and c) carries on its surface catalytically active metals or metallic compounds.

Description

Magnetism and Magnetic Materials £ H (1990) 285). However, this method is limited to magnetic metals and, in the case of larger particles, also has the difficulty that the particles agglomerate into larger particles by permanent magnetization.

The immobilization of enzymes by binding to magnetic particles is e.g. described in EP-A 125995. However, the use of these enzymes is restricted to mild reaction conditions under which the enzymes bound in this way are chemically stable.

The object was to provide metal-containing catalysts for reactions in the liquid phase which can be separated from the reaction mixture in a technically simple manner.

Accordingly, the catalysts described above have been found. Furthermore, a process for their preparation, their use and a process for separating these catalysts from reaction mixtures were found.

The core of the catalysts according to the invention consists of a magnetizable particle. Magnetizable particles are understood to mean those particles which become magnetic in an external magnetic field. Such substances generally have a saturation magnetization of 20 to 200 nTm ³ / g, preferably 30 to 100 nTm ³ / g. The size of the magnetizable particles can be selected within wide limits. However, if permanent magnetization of these particles by an external magnetic field is to be avoided, it has proven to be advantageous to use particles with diameters of 5 to 1000 nm. Particles with diameters of 5 to 100 nm are particularly preferred. The size of particles with such diameters is determined by known methods, for example by electron microscopic methods, the values representing average values of the respective sample.

The following substances can be considered as magnetizable cores:

Iron, nickel, cobalt, chromium dioxide, iron oxides as well as cubic and hexagonal ferrites such as with manganese, zinc and cobalt ions as well as ferrites doped with magnesium, calcium, strontium and barium ions. Such substances can be obtained in a manner known per se, for example by precipitation reactions of corresponding metal salts. For example, magnetite Fe ₃ 0 _{4 can be produced} from solutions of Fe ²⁺ / Fe ³⁺ chlorides by precipitation with sodium hydroxide solution, for example DE-A 36 19 746, chromium dioxide by hydrothermal synthesis, see for example EP-A 27 640. The metallic cores can by thermal decomposition of metal carbonyls (for example US Pat. No. 3,228,881) can be produced. Preferred Materials for the magnetizable cores are magnetite, γ-Fe ₂ 0, chromium dioxide and manganese-zinc ferrite.

According to their generally small diameter, the magnetizable cores generally have surfaces (determined according to DIN 66 132) of 1 to 300 m2 g.

The magnetizable cores can be reacted directly with metal compounds that bind adsorptively or chemically to the surface of the core. It is also possible to produce magnetizable cores, such as magnetite, which can be produced by precipitation in the presence of metal compounds, so that the active metals also co-precipitate or are adsorptively or chemically bound to the freshly precipitated magnetizable cores. However, the magnetic core is preferably first coated with a binder. This binder should bind adsorptively or chemically to the magnetizable core and, at the same time, offer the possibility of binding adsorptively or chemically metal compounds which are directly or optionally after a chemical modification. decoration are catalytically active.

Amines such as pyridine or 4-pyridineethanesulfonic acid can be mentioned as monomeric binders. Organic polymers which are water-soluble or water-dispersible are preferred as binders according to the invention, ie that in general at least 1 g can be dissolved or dispersed in 1 liter of water. The following may be mentioned as monomers for such polymeric binders: olefinically unsaturated compounds containing acid groups, such as unsaturated carboxylic acids, for example acrylic acid, methacrylic acid, unsaturated sulfonic acids, for example vinylsulfonic acid, unsaturated phosphonic acids, such as vinylphosphoric acid, furthermore unsaturated anhydrides, such as maleic anhydride, monomers carrying amino groups, such as vinylla min, amide group-bearing monomers such as acrylamide, further vinyl pyrrolidine, vinyl pyrrolidone, vinyl pyridine, vinyl phenanthroline, vinyl imidazole and vinyl bipyridyl. Homopolymers and copolymers of the monomers mentioned can be used. Polyvinylpyridine can also be used in partially oxidized form as polyvinylpyridine-polyvinylpyridine-N-oxide. The polymers can contain further copolymerizable monomers, but the proportion of said monomers is preferably at least 50% by weight. Homopolymers or copolymers of these compounds are commercially available or can be obtained, for example, by radical polymerization. Polyesters such as polylactite are also suitable as binders. Polyacrylic acids with an average molecular weight of 1,000 to 1,000,000 are preferred. Polymers which have up to 20% by weight of other monomers apart from acrylic acid are also suitable. Such products are commercially available.

The amount of the binder is generally such that at least one monolayer of the binder can form on the magnetizable core. This generally requires 0.1 to 5 mg of polymer per square meter of specific surface area of the magnetizable core, 0.3 to 1.5 mg being preferred.

To coat the magnetizable core with a binder, the magnetizable material in a polar solvent such as water can be mixed with a solution of the binder in a polar solvent such as water. The temperature is usually 10 to 100 ° C. The components are generally stirred for 10 to 60 minutes, the solid so obtained is e.g. isolated by filtration or by applying a magnetic field and optionally dried. The bound polymer content can be determined by elemental analysis.

It is furthermore possible to further treat the solids thus obtained in such a way that reactive groups which are present in the polymer are subjected to a reaction. Here, e.g. polar carboxyl groups are released in a manner known per se by saponification with a mineral base from ester groups contained in the binder.

The catalysts of the invention have metals or metal compounds on their surface. These are preferably the platinum metals ruthenium, rhodium, palladium, osmium, iridium and platinum, furthermore copper, silver, gold and rhenium, or compounds of these metals. Ruthenium, palladium and platinum are particularly preferred. To produce the catalysts according to the invention, metal compounds which are dissolved or finely suspended in a polar solvent can be chemically or adsorptively bonded to the magnetizable cores, which are optionally coated with a binder. These metal compounds are, for example, salts of the metals, such as acetates and nitrates. Examples include ruthenium chloride trihydrate, ruthenium oxide hydrate, palladium acetate, palladium chloride, rhodium chloride, platinum chloride, gold chloride, osmium tetraoxide, copper chloride, copper nitrate, silver nitrate and rhenium chloride. The solvents include C 1 -C ₄ alcohols such as methanol, ethanol, isopropanol and tert-butanol, ethers such as tetrahydrofuran, water, pyridine or mixtures of these solvents, but preferably water. Depending on the po- Laral groups, the metal compounds can be bound by interactions with, for example, carboxyl groups, amino groups or oxo groups. In the case of colloidal metal compounds such as ruthenium oxide hydrate, an adsorptive bond can take place. As a rule, 0.1 to 20% by weight of the metal compound, based on the magnetizable core, is reacted in solution with the magnetic particle which may contain a binder. In general, the reaction is carried out at room temperature, but it can also be carried out at 0 to 100 ° C. It usually ends after 1 to 6 hours.

The products thus obtained can be used directly in solution

Catalysts are used, but they can also be isolated first, cleaned if necessary and then fed to the reaction to be catalyzed.

The catalysts of the invention allow the catalysis of a variety of different reactions, e.g.

- Hydrogenation of aromatic nuclei in the presence of further reducible groups with ruthenium-containing catalysts, hydroformylation of olefins with rhodium-containing catalysts, transvinylidation of vinyl ethers with palladium-containing catalysts, selective hydrogenation of carbon-carbon triple bonds to double bonds with palladium containing catalysts.

The catalysts can generally be used up to temperatures of up to 250 ° C., and the pressure in the reactions can be chosen as desired. The catalysts of the invention are through a magnetic filter, such as e.g. in Journal of Magnetism and Magnetic Materials fiü (1990) 285, can be separated from the reaction mixtures. A simple bar magnet has proven itself for the removal of small amounts of the catalyst.

The catalysts of the invention also have the advantage that they are not permanently magnetic after removal of the magnetic field used for the separation and thus do not agglomerate. This considerably facilitates the recycling of the catalysts into the reaction and their uniform distribution in the reaction mixture. Examples

Production of the magnetizable particles

Example 1 Magnetite Fe ₃ 0 was prepared as follows:

The magnetite was prepared tion according to DE-A 35 00 471 by a Fällungsreak¬ by adding a stoichiometric solution of Fe ^<2+) / Fe ⁽³⁺ was ^dropped) chlorides in water to a solution of sodium hydroxide ^'in water. The precipitating magnetite was filtered and washed free of chloride. A filter cake with a magnetite content of 26% by weight was obtained. The dried pigment was characterized by the following measured values: The specific BET surface area was measured in accordance with DIN 66 132. It was 51 m ² / g. The magnetic properties were determined using a vibration magnetometer. The saturation magnetization was 85 nTm ³ / g.

Production of catalysts according to the invention

Example 2 (Fe-Pd catalyst)

A solution of 54.2 g FeCl ₃ x 6H ₂ 0, 31.5 g FeCl ₂ x 4H ₂ 0, 4.7 g PdCl and 110 ml water became a solution of 38.5 at 20 ° C within 19 minutes g of NaOH and 110 ml of water were added dropwise. The suspension was heated to 70 ° C. in the course of 10 minutes and stirred at this temperature for one hour. A pH of 9.1 was set by adding 1 g of 50% NaOH solution. After cooling to room temperature, the pH was again adjusted to pH 9 with 10% HCl solution. The suspension was then filtered under nitrogen and washed with water. After drying, a pigment with the following properties was obtained: Fe content: 61% by weight, Pd content: 6.5% by weight, Cl content: 0.04% by weight. The specific BET surface area was 95 m ² / g, the saturation magnetization 52 nTm ³ / g.

Example 3 (Ru catalyst)

3.1 Production of ruthenium oxide hydrate as a catalytically active metal compound

The reaction was carried out according to Example 1 from DE-A 2132547. The ruthenium oxide hydrate was used in the form of a moist filter cake with a content of 8.4% by weight of ruthenium for the following experiments. 3.2 Preparation of the catalyst according to the invention

230 g of filter cake with 60 g of the magnetizable particles produced according to Example 1 and 71.3 g of the filter cake produced according to Example 3.1 were dispersed in 200 g of water by vigorous stirring for 15 minutes. A solution of 1.8 g of polyacrylic acid with an average molecular weight of 250,000 in 3.3 g of water was then added. The pH was adjusted to 7.9 by adding 13.4 g of a 5% strength by weight sodium hydroxide solution.

10 After 15 minutes the solid was filtered off and washed free of chloride with water. The filter cake was then washed with tetrahydrofuran THF and the water was largely replaced by THF. The filter cake obtained in this way was characterized as follows: ruthenium content: 2.1% by weight. Solids content (

15 is correct by drying at 70 ° C. in a vacuum): 22% by weight, BET surface area 86 m 2 / g.

Example 4 (Fe-Pd Catalyst)

20 4.1 Production of the polymeric binder

A solution was prepared by mixing 30 g of polyacrylate (35% by weight in water) with an average molecular weight of 250,000 with 5.7 g of NaOH and 15 g of water. This solution 25 had a pH of 6.8 and contained 27% by weight of sodium polyacrylate.

4.2 Coating magnetite with polymer

20 g of magnetite pigment, which was characterized by a specific 30 BET surface area of 80 m ² / g and a saturation magnetization of 72 nTm ³ / g, in 54 g of water and 2.2 g of the solution according to Example 4.1 with 200 g of water dispersed intensively for one hour under nitrogen and with cooling to room temperature. 375 g of pH 8.5 suspension were obtained.

35

4.3 Coating with palladium

187 g of the suspension according to Example 4.2 were mixed with a solution of 1.67 g of PdCl ₂ and 23 g of 40 10% HCl in 400 g of water within 50 minutes with stirring. The pH was kept in the range 6.0 to 8.6 by uniform addition of 5% by weight NaOH solution.

The suspension was filtered, washed with 150 ml of water and dried at 70 ° C. in a water jet vacuum. 11.9 g of solid were obtained, which was characterized as follows: Specific BET surface area was 78 m ² / g. Fe content: 60% by weight, Pd content: 8% by weight, Cl content: 0.5% by weight, C content: 1% by weight.

Example 5 (Fe-Pd Catalyst)

1.67 g of PdCl ₂ and 31 g of pyridine were added to a solution of 2 g of polyvinylpyrrolidone (K value: 27-32, molecular weight 44,000-54,000) in 400 g of water. The pH was 8.65. 20 g of magnetite pigment, which was characterized by a specific BET surface area of 76 m ² / g and a saturation magnetization of 73 nTm ³ / g, were then added in 29 g of water and the mixture was stirred at room temperature for 3 h. The suspension was evaporated to constant weight at 80 to 95 ° C. on a rotary evaporator under a water jet vacuum. 28 g of pigment were obtained, on which the following measurement results were determined: the specific BET surface area was 21 m ² / g, the saturation magnetization was 6.5 nTm ³ / g. Fe content: 55% by weight, Pd content: 3.6% by weight, Cl content: 3.1% by weight, C content: 8% by weight, N content: 1.8% by weight.

Example 6 (Fe-Pd-Ag catalyst)

A mixture of 10.55 g of Pd (CH C0), 108 g of pyridine and 60 g of water was prepared at room temperature. 53 g of magnetite, which was characterized by a specific BET surface area of 74 m ² / g and a saturation magnetization of 77 nTm ³ / g, was stirred into this to 102 g of water. The mixture was evaporated to constant weight at 90 ° C. on a rotary evaporator under a water jet vacuum. A pigment was obtained on which the following measurement results were determined: the specific BET surface area was 58 m ² / g, the saturation magnetization was 66 nTm ³ / g. Fe content: 58% by weight, Pd content: 5.8% by weight, Cl content: 0.6% by weight, C content: 5.3% by weight, N content: 0.7% by weight. 10 g of the above pigment were mixed with 30 g of 1% by weight AgNO ₃ solution and then evaporated to constant weight at 90 ° C. on a rotary evaporator under a water jet vacuum.

Example 7 (Rh catalyst)

A solution of 10 g of poly-4-vinylpyridine / poly-4-vinylpyridine-N-oxide with an oxidation degree of 67% and a K value (1% in NaCl 5%) of 14.2 in 250 g of water brought to pH 9.6 by adding 37 g of 5% NaOH solution. This polymer solution was added to 100 g of a magnetite with a BET surface area of 59 m ² / g and a saturation magnetization of 79 nTm ³ / g, stirred in, mixed with a further 400 g of water and then

Homogenized intensively for 1 hour under nitrogen blanket and ice cooling. A pH of 6.5 was measured in the mixture was increased to pH 7.6 by adding 49 g of 5% NaOH solution.

A solution of 280 milligrams of Rh (NO ₃ ) ₃ in 30 g of water was added to this suspension. The mixture was dispersed for a further 15 minutes. A pH of 7.3 was measured. The suspension was then dried at 80 ° C. on a rotary evaporator and in a water-jet vacuum and finally ground to dust. The magnetic dust was examined: the BET surface area was 30 m ² / g. The saturation magnetization was 79 nTm ³ / g.

Coating magnetite with a binder

Example 8

237 g of filter cake with 100 g of magnetite as in Example 7 were mixed with a solution of 10 g of (4-) pyridineethanesulfonic acid and 2 g of NaOH in 538 g of water and homogenized intensively for 1 hour with nitrogen blanketing and ice cooling. After the addition of 15 g of 5% NaOH solution, a pH of 7.3 was measured in the mixture. The suspension was dried at 90 ° C. on a rotary evaporator and in a water jet vacuum and finally ground to dust. The magnetic dust was examined: the BET surface area was 46 m ² / g. The saturation magnetization was 78 nTm ³ / g, the remanence 6 nTm ³ / g.

Example 10

237 g of filter cake with 100 g of magnetite as in Example 7 were mixed with a solution of 10 g of poly-4-vinylpyridine-N-oxide (degree of oxidation: 50%, K value = 22.4) in 250 g of water a total of 40 g of 5% NaOH were added and the mixture was homogenized intensively for 1 hour under nitrogen blanket and ice-cooling. The pH of the mixture was measured at 7.5. The suspension was dried at 90 ° C on a rotary evaporator and in a water jet vacuum and finally ground to dust. The magnetic dust was examined: the BET surface area was 39 m ² / g. The saturation magnetization was 77 nTm ³ / g, the remanence 6 nTm ³ / g.

The coated magnetites according to Examples 8 to 10 could be converted into catalysts with rhodium as the active metal in analogy to Example 7. Review of the catalytic properties

Example 11

Selective hydrogenation with an Ru catalyst

70 g of bisphenol-F-bisglycidyl ether (produced by condensation of formaldehyde and 2 equivalents of phenol and subsequent reaction with epichlorohydrin) and 10 g of the ruthenium catalyst obtained according to Example 3 (corresponding to 3% by weight Ru.) based on the bisglycidyl ether) with THF to a total weight of 150 g. The mixture was then heated at 50 to 67 ° C. for 7 hours at a hydrogen pressure of 100 bar. The total turnover was 94%. The epoxy equivalent was 192.

This value corresponds to epoxy equivalent values as used in the prior art, e.g. EP-A 402 743 are available.

The catalyst could be completely and easily separated from the reaction mixture using a magnet.

Example 12

Umvinylierung with an Fe-Pd catalyst

12.1 vinyl 2-ethylhexyl ether

3 g of catalyst according to Example 2 were added to 130.2 g (1 mol) of 2-ethylhexanol and 500 g (5 mol) of vinyl isobutyl ether, and the mixture was stirred at 83 ° C. for 4 hours. At the end of the reaction time, the conversion (based on 2-ethylhexanol) was 72%, the selectivity with regard to the product of value was 95%. After the catalyst had been separated off, the reaction mixture was subjected to fractional distillation (using a magnetic filter), the excess vinyl isobutyl ether and the unreacted 2-ethylhexanol being recovered. 101.5 g of C-90.2% were obtained, based on the converted 2-ethylhexanol) vinyl 2-ethylhexyl ether.

12.2 Analog to Example 12.1, but with 3 g of the catalyst according to Example 4

106.5 g (92%) of vinyl 2-ethylhexyl ether were obtained with a conversion of 74% and a selectivity of 94% after working up by distillation. 12.3 Analogue Example 12.1, but with a catalyst according to Example 5 with a reaction time of 3 hours, conversion 76%, selectivity 98% yield: 110 g (94.5%)

Example 13

Vinyloxypivalinsäuremethylester

198.4 g (1.5 mol) of hydroxypivalic acid methyl ether and 750 g (7.5 mol) of vinyl isobutyl ether were mixed with 3 g of catalyst according to Example 5 and stirred at 70 ° C. for 8 h. After 8 hours, the conversion with respect to methyl hydroxypivalate was 70%. After removal of the catalyst using a magnetic filter and after working up by distillation, 164 g (69.1%) of valuable product were obtained.

Claims

claims

1. Catalysts made up of

a) a magnetizable core, b) which optionally coated with a binder, and transmits c) which catalytically active metals on its surface ^'or metal compounds.

2. Catalysts according to claim 1, in which the magnetizable core consists of an iron oxide, chromium dioxide or a manganese-zinc ferrite.

3. Catalysts according to claim 1 or 2, in which the magnetisable core has a diameter of 5 to 1000 nm.

4. Catalysts according to claims 1 to 3, in which the catalytically active metals or metal compounds from the

Group of platinum metals as well as copper, silver, gold and rhenium are selected.

5. Catalysts according to claims 1 to 4, in which the binding agent is a polyacrylic acid with an average molecular weight of 1000 to 1,000,000.

6. Catalysts according to claims 1 to 3, in which the catalytically active metal component is ruthenium oxide hydrate.

7. Catalysts according to claims 1 to 3, in which the active metal is palladium (II).

8. A process for the preparation of catalysts according to claim 1, characterized in that magnetizable particles, if appropriate after being mixed with a solution which contains a binder which binds adsorptively or chemically to the magnetizable particles, with one converts its surface adsorptively or chemically binding metal compound.

9. Use of catalysts according to claim 6 for Kern¬ hydrogenation of aromatic rings containing bisglycidyl ethers.

10. Use of catalysts according to claim 7 for the synthesis of vinyl ethers by transvinylation.

11. A process for the separation of catalysts according to claim 1 from reaction solutions, characterized in that the catalysts are removed by applying a magnetic field.