Methods for preparing bimetallic cyanide catalysts

Abstract

This invention relates to a method for preparing a bimetallic cyanide (DMC) catalyst, comprising a reaction of an aqueous solution of a cyanide-free metal salt, an aqueous solution of a basic metal cyanide salt, an organic complexing ligand, and optionally a component forming a complex, wherein the metal cyanide salt is one or more compounds selected from potassium hexacyanocobalt(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobalt(III), and lithium hexacyanocobalt(III), wherein the organic complexing ligand is one or more compounds selected from dimethoxyethane, tert-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3-butyn-2-ol, ethylene glycol mono-tert-butyl ether, and 3-methyl-3-oxetane-methanol, and wherein the basic metal cyanide salt used has an alkalinity between 0.700 wt% and 3.000 wt% sodium hydroxide (NaOH) based on the total weight of the basic metal cyanide salt used, determined by titration as disclosed in the experimental section. Another subject of the invention includes a bimetallic cyanide catalyst (DMC) obtainable by the method according to the invention, and the use of said DMC catalyst in the preparation of polyoxyethylene polyols.

Description

[0001] This invention relates to a method for preparing a bimetallic cyanide catalyst (DMC), comprising a reaction of an aqueous solution of a cyanide-free metal salt, an aqueous solution of a basic metal cyanide salt, an organic complexing ligand, and optionally a component forming a complex, wherein the metal cyanide salt is one or more compounds selected from potassium hexacyanocobalt(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobalt(III), and lithium hexacyanocobalt(III), wherein the organic complexing ligand is one or more compounds selected from dimethoxyethane, tert-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3-butyn-2-ol, ethylene glycol mono-tert-butyl ether, and 3-methyl-3-oxetane-methanol, and wherein the basic metal cyanide salt used has an alkalinity between 0.700 wt% and 3.000 wt% sodium hydroxide (NaOH) based on the total weight of the basic metal cyanide salt used, determined by titration as disclosed in the experimental section. Another subject of the invention includes a bimetallic cyanide catalyst (DMC) obtainable by the method according to the invention and the use of said DMC catalyst in the preparation of polyoxyethylene polyols.

[0002] DMC catalysts are known in principle in the prior art (see, for example, US-A 3 404 109, US-A 3 829505, US-A 3 941 849 and US-A 5 158 922). For example, DMC catalysts described in US-A 5 470 813, EP-A 700 949, EP-A 743093, EP-A 761 708, WO 97 / 40086, WO 98 / 16310 and WO 00 / 47649 exhibit extremely high activity in the homopolymerization of epoxides and can prepare polyether polyols at very low catalyst concentrations (25 ppm or less), thus typically eliminating the need to separate the catalyst from the finished product. A typical example is the highly active DMC catalyst described in EP-A 700 949, which contains not only bimetallic cyanide compounds (e.g., zinc hexacyanocobalt(III)ate) and organic complexing ligands (e.g., tert-butanol), but also polyethers with a number average molecular weight greater than 500 g / mol.

[0003] US 5,783,513 discloses a method for preparing a substantially amorphous DMC catalyst, wherein the metal salt used for catalyst preparation, such as zinc chloride, has an alkalinity between 0.2 wt% and 2 wt% (expressed as wt% ZnO).

[0004] EP 1 634 644 A1 discloses a method for preparing a substantially amorphous DMC catalyst by reacting a metal salt and a metal cyanide salt at a low molar ratio of less than 2.9:1 and an alkalinity content of at least 2% by weight of the metal salt based on the metal oxide.

[0005] US 6,716,788 discloses a method for preparing a DMC catalyst by reacting a metal salt, such as zinc chloride, with a metal cyanide salt, such as potassium hexacyanocobaltate, in the presence of an alkaline metal compound in an amount of 0.03-0.4 moles based on the amount of the metal salt.

[0006] WO 2011 / 144523 A1 discloses a method for preparing polyether carbonate polyols from one or more H-functional initiator substances, one or more epoxides, and carbon dioxide in the presence of at least one bimetallic cyanide catalyst, wherein the cyanide-free metal salt, metal cyanide salt, or both of these salts used to prepare the bimetallic cyanide catalyst reacts in the presence of a basic metal hydroxide, metal carbonate, and / or metal oxide in an amount of 0.3 to 1.8 moles (based on 1 mole of metal cyanide salt used for catalyst synthesis). These DMC catalysts bring improved selectivity for forming linear polyether carbonate polyols and the lowest possible ratio of cyclic carbonates to linear polyether carbonates.

[0007] EP 700 949 A2 describes a DMC catalyst containing a DMC compound, an organic complexing ligand, and 5%–80% by weight of a polyether with a number-average molecular weight > 500 g / mol. The catalyst used is typically active in the preparation of polyether polyols.

[0008] EP 3 608 018 A1 discloses a method for preparing a bimetallic cyanide catalyst (DMC), comprising reacting an aqueous solution of a cyanide-free metal salt, an aqueous solution of a metal cyanide salt, an organic complexing ligand, and a component forming a complex to form a dispersion, wherein the reaction is carried out using a mixing nozzle and wherein the process temperature of the dispersion during the reaction is between 26°C and 49°C. Further subject matter of this disclosure includes bimetallic cyanide catalysts (DMC) obtainable by the disclosed method and the use of said DMC catalysts in the preparation of polyoxyethylene polyols.

[0009] The prior art does not disclose the correlation between the basicity of the metal cyanide salt used to prepare DMC dispersions and its effect on the activity of DMC catalysts used to form polyoxyethylene polyols.

[0010] The purpose of this application is to provide an improved method for preparing bimetallic cyanide (DMC) catalysts, said catalysts having further enhanced catalytic activity in the preparation of polyoxyethylene polyols, preferably polyether polyols and / or polyether carbonate polyols, wherein such enhanced activity, for example, leads to a reduction in product viscosity in catalyst tests according to, for example, the “8K Diol Stressed Tests” described in WO 98 / 16310 A1. The aim is therefore to provide more catalytically active DMC catalysts that result in lower viscosity polyoxyethylene polyols, preferably polyether polyols and / or polyether carbonate polyols, which benefits the further processability of the polyoxyethylene polyols in subsequent polyurethaneization reactions. The enhanced catalytic activity also allows for a reduction in catalyst dosage, which improves the economic feasibility of the method.

[0011] Surprisingly, it has now been discovered that a method for preparing bimetallic cyanide catalysts (DMC) achieves the above-mentioned objective, the method comprising:

[0012] i) Reactions of aqueous solutions of cyanide-free metal salts, aqueous solutions of basic metal cyanide salts, organic complexing ligands, and optionally, the components that form the complex.

[0013] The metal cyanide salt is one or more compounds selected from potassium hexacyanocobalt(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobalt(III), and lithium hexacyanocobalt(III), and the organic complexing ligand is one or more compounds selected from dimethoxyethane, tert-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3-butyn-2-ol, ethylene glycol mono-tert-butyl ether, and 3-methyl-3-oxetane-methanol.

[0014] The basic metal cyanide salt used is characterized by having an alkalinity between 0.700% by weight and 3.000% by weight of sodium hydroxide (NaOH) based on the total weight of the basic metal cyanide salt used, determined by the titration method disclosed in the experimental section.

[0015] The cyanide-free metal salt suitable for preparing bimetallic cyanide compounds preferably has the general formula (I).

[0016] M(X) n (I)

[0017] in

[0018] M is selected from the metal cation Zn. 2+ Fe 2+ Ni 2+ Mn 2+ Co 2+ 、Sr 2+ Sn2+ Pb 2+ and Cu 2+ M is preferred for Zn 2+ Fe 2 + Co 2+ or Ni 2+ ,

[0019] X is one or more (i.e. different) anions, preferably selected from anions of halide ions (i.e. fluoride ions, chloride ions, bromide ions, iodide ions), hydroxide ions, sulfate ions, carbonate ions, cyanate ions, thiocyanate ions, isocyanate ions, isothiocyanate ions, carboxylate ions, oxalate ions, and nitrate ions.

[0020] When X = sulfate, carbonate, or oxalate, n is 1, and

[0021] When X = halide ion, hydroxide ion, cyanate ion, thiocyanate ion, isocyanate ion, isothiocyanate ion, or nitrate ion, n is 2.

[0022] Or a suitable cyanide-free metal salt having the general formula (II).

[0023] M r (X)3 (II)

[0024] in

[0025] M is selected from the metal cation Fe. 3+ Al 3+ and Cr 3+ ,

[0026] X is one or more (i.e. different) anions, preferably selected from anions of halide ions (i.e. fluoride ions, chloride ions, bromide ions, iodide ions), hydroxide ions, sulfate ions, carbonate ions, cyanate ions, thiocyanate ions, isocyanate ions, isothiocyanate ions, carboxylate ions, oxalate ions, and nitrate ions.

[0027] When X = sulfate, carbonate, or oxalate, r is 2, and

[0028] When X = halide ion, hydroxide ion, cyanate ion, thiocyanate ion, isocyanate ion, isothiocyanate ion, carboxylate ion, or nitrate ion, r is 1.

[0029] Or a suitable cyanide-free metal salt having the general formula (III)

[0030] M(X) s (III)

[0031] in

[0032] M is selected from the metal cation Mo. 4+ V 4+ and W4+ ,

[0033] X is one or more (i.e. different) anions, preferably selected from anions of halide ions (i.e. fluoride ions, chloride ions, bromide ions, iodide ions), hydroxide ions, sulfate ions, carbonate ions, cyanate ions, thiocyanate ions, isocyanate ions, isothiocyanate ions, carboxylate ions, oxalate ions, and nitrate ions.

[0034] When X = sulfate, carbonate, or oxalate, s is 2, and

[0035] When X = halide ion, hydroxide ion, cyanate ion, thiocyanate ion, isocyanate ion, isothiocyanate ion, carboxylate ion, or nitrate ion, s is 4.

[0036] Or a suitable cyanide-free metal salt has the general formula (IV),

[0037] M(X) t (IV)

[0038] in

[0039] M is selected from the metal cation Mo. 6+ and W 6+ ,

[0040] X is one or more (i.e. different) anions, preferably selected from anions of halide ions (i.e. fluoride ions, chloride ions, bromide ions, iodide ions), hydroxide ions, sulfate ions, carbonate ions, cyanate ions, thiocyanate ions, isocyanate ions, isothiocyanate ions, carboxylate ions, oxalate ions, and nitrate ions.

[0041] When X = sulfate, carbonate, or oxalate, t is 3, and

[0042] When X = halide, hydroxide, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, or nitrate, t is 6.

[0043] In a preferred embodiment of the method according to the invention, the cyanide-free metal salt in the aqueous solution of the cyanide-free metal salt is one or more compounds selected from zinc chloride, zinc bromide, zinc iodide, zinc acetate, zinc acetylacetone, zinc benzoate, zinc nitrate, ferric sulfate (II), ferric bromide (II), ferric chloride (II), cobalt chloride (II), cobalt thiocyanate (II), nickel chloride (II), and nickel nitrate (II).

[0044] In the method according to the invention, the basic metal cyanide salt used has an alkalinity between 0.700 wt% and 3.000 wt% sodium hydroxide (NaOH) based on the total weight of the basic metal cyanide salt used, wherein the alkalinity is determined by titration with 0.1 mol / L hydrochloric acid using the method disclosed in the experimental section. Here, according to the generally known Brønsted acid-base concept, the alkalinity according to the invention is understood to refer to the amount of Brønsted acid that must be added to the system containing the Brønsted base (in the invention, the basic metal cyanide salt) to achieve neutralization of the basic metal cyanide salt, i.e., to achieve pH 7. In this case, the Brønsted acid is understood to be a proton-donating compound (proton donor), and the Brønsted base is correspondingly understood to be a proton-accepting compound (proton acceptor). Examples of Brønsted acids include, for example, hydrochloric acid, nitric acid, or sulfuric acid, wherein examples of Brønsted bases include metal hydroxides, metal carbonates, and / or metal oxides.

[0045] In one embodiment of the method according to the invention, the alkalinity is between 0.700 wt% and 2.000 wt% NaOH, preferably between 0.800 wt% and 1.500 wt% NaOH, wherein the alkalinity is determined by titration as disclosed in the experimental section. Particularly for alkalinity between 0.800 wt% and 1.500 wt% NaOH, this again results in improved catalyst activity and thus reduced viscosity of polyether polyols and / or polyether carbonate polyols.

[0046] In the method according to the invention, the basic metal cyanide salt is understood to be a metal cyanide salt as defined below, having an alkalinity between 0.700% by weight and 3.000% by weight based on the total weight of the basic metal cyanide salt used and determined by titration according to the method disclosed in the experimental section. Here, the alkalinity according to the method of the invention is defined as described above.

[0047] In one embodiment of the method according to the invention, the alkaline metal cyanide salt used contains a metal hydroxide, a metal carbonate, and / or a metal oxide, wherein the metal hydroxide, metal carbonate, and / or metal oxide causes the alkalinity of the alkaline metal cyanide salt used.

[0048] In one embodiment of the method according to the invention, the basic metal cyanide salt used can be obtained by adding a metal hydroxide, a metal carbonate, and / or a metal oxide during the preparation of the basic metal cyanide salt. In this case, an appropriate amount of a solution of metal hydroxide, metal carbonate, and / or metal oxide can be added during the preparation of the metal cyanide salt. For example, a solution of metal hydroxide, metal carbonate, and / or metal oxide, such as sodium hydroxide or potassium hydroxide, can be added during the reaction of an alkali metal and / or alkaline earth metal cyanide solution, such as potassium cyanide or sodium cyanide solution, and a metal halide solution, such as cobalt halide, nitrate, or sulfate solution.

[0049] In an alternative embodiment of the method according to the invention, the basic metal cyanide salt used may be obtained by reacting the metal cyanide salt with a metal hydroxide, a metal carbonate, and / or a metal oxide. Here, in the first method step, the metal cyanide salt is prepared by methods known to those skilled in the art, such as potassium hexacocbaltaate (Kalium hexacyanocobaltat(III), Hollemann-Wiberg, Lehrbuch der AnorganischenChemie, 101st edition, de Gruyter, pp. 1552-1553), and then mixed with appropriate amounts of metal hydroxide, metal carbonate, and / or metal oxide, such as potassium hydroxide and / or sodium hydroxide, wherein the respective solids of the metal cyanide salt are mixed with the metal hydroxide, metal carbonate, and / or metal oxide in a suitable manner (mixing element). Alternatively, a suspension and / or solution of a metal cyanide salt, such as an aqueous solution of potassium hexacyanocobalt(III) acidate, may be mixed with a suspension or solution of a metal hydroxide, a metal carbonate, and / or a metal oxide, such as an aqueous solution of potassium hydroxide and / or sodium hydroxide, and then the suspension medium or solvent may be separated in a suitable manner to obtain a basic metal cyanide salt, such as basic potassium hexacyanocobalt(III) acidate.

[0050] In one embodiment of the method according to the invention, one or more metals from Group 1 or Group 2 of the periodic table are used as metal hydroxides, metal carbonates and / or metal oxides (see, for example, "Handbook of Chemistry and Physics, 63rd edition").

[0051] In one embodiment of the method according to the invention, the alkaline metal hydroxide, metal oxide and / or metal carbonate is one or more compounds selected from sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, calcium oxide, calcium hydroxide, barium hydroxide and barium oxide.

[0052] In the method according to the invention, the metal cyanide salt in the aqueous solution of the metal cyanide salt is one or more compounds selected from potassium hexacyanocobalt(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobalt(III) and lithium hexacyanocobalt(III), preferably potassium hexacyanocobalt(III).

[0053] The preferred bimetallic cyanide compound contained in the DMC catalyst according to the present invention is a compound of general formula (V).

[0054] M x [M' x (CN) y ] z (V),

[0055] Where M is defined as in equations (I) to (IV), and

[0056] M' = Co(III), Fe(II) or Fe(III), and

[0057] x, x', y, and z are integers and are chosen to ensure the electronic neutrality of the bimetallic cyanide compound.

[0058] The preferred option is

[0059] x = 3, x' = 1, y = 6 and z = 2,

[0060] M = Zn(II), Fe(II), Co(II) or Ni(II) and

[0061] M' = Co(III) or Fe(III).

[0062] In a preferred embodiment of the method according to the invention, the bimetallic cyanide compound is one or more compounds selected from zinc hexacyanocobalt(III), zinc hexacyanoferrate(III), and cobalt(II) hexacyanocobalt(III). Zinc hexacyanocobalt(III) is particularly preferred.

[0063] In the method according to the invention, the organic complexing ligand is one or more compounds selected from dimethoxyethane, tert-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3-butyn-2-ol, ethylene glycol mono-tert-butyl ether, and 3-methyl-3-oxetane methanol, preferably tert-butanol.

[0064] In one embodiment of the method according to the invention, a component that forms a complex is used.

[0065] The components forming the complex according to the present invention may be selected from the following compound classes: polyether, polyester, polycarbonate, polyalkylene glycol sorbitol ester, polyalkylene glycol glycidyl ether, polyacrylamide, poly(acrylamide-co-acrylic acid), polyacrylic acid, poly(acrylic acid-co-maleic acid), polyacrylonitrile, polyalkyl acrylate, polyalkyl methacrylate, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone, poly(N-vinylpyrrolidone-co-acrylic acid), polyvinyl methyl ketone, poly(4-vinylphenol), poly(acrylic acid-co-styrene), oxazoline polymer, polyalkylimide, maleic acid and maleic anhydride copolymer, hydroxyethyl cellulose and polyacetal, or glycidyl ether, glycoside, polyol carboxylic acid ester, ester or amide, cyclodextrin and / or phosphorus compound.

[0066] In the method for preparing DMC catalyst according to the present invention, polyether is preferably used as the component forming the complex.

[0067] In a preferred embodiment, the polyether has a number-average molecular weight of ≥ 500 g / mol, wherein the number-average molecular weight is calculated from the measured OH value.

[0068] The OH value was determined according to the method in DIN 53240.

[0069] Suitable polyethers include those prepared by ring-opening polymerization of cyclic ethers, such as oxetane polymers and tetrahydrofuran polymers. Various catalysts can be used for this purpose. The polyethers here have suitable end groups, such as hydroxyl, amine, ester, or ether end groups.

[0070] In a particularly preferred embodiment, the polyether has an average hydroxyl functionality of 2 to 8 and a number-average molecular weight of 500 g / mol to 10000 g / mol, preferably 700 g / mol to 5000 g / mol, wherein the number-average molecular weight is calculated from the measured OH value.

[0071] In a particularly preferred embodiment, the polyether is a polyether polyol, wherein the polyether polyol is obtained by reacting an epoxide and an H-functional initiator compound in the presence of an acidic, basic, and / or organometallic catalyst. These organometallic catalysts are, for example, bimetallic cyanide catalysts (DMC).

[0072] Suitable polyether polyols are poly(oxypropylene) polyols, poly(oxypropylene)oxyethylene polyols, polytetramethylene ether glycols, and block copolymers containing poly(oxy)ethylene, poly(oxy)propylene, and / or poly(oxy)butene blocks, such as poly(oxy)ethylene-poly(oxy)propylene block copolymers with terminal poly(oxy)ethylene blocks.

[0073] In a preferred embodiment, the polyether polyol is a poly(oxypropylene) polyol having a number-average molecular weight of ≥ 500 g / mol, wherein the number-average molecular weight is calculated from the measured OH value.

[0074] In a particularly preferred embodiment, the polyether polyol is a poly(oxypropylene) polyol having a number-average molecular weight of 700 g / mol to 4000 g / mol, preferably poly(oxypropylene) diol and / or poly(oxypropylene) triol, wherein the number-average molecular weight is calculated from the measured OH value.

[0075] In an alternative embodiment, the polyether has an average hydroxyl functionality of 2 to 8 and a number-average molecular weight of 150 g / mol to less than 500 g / mol, preferably 200 g / mol to 400 g / mol, wherein the number-average molecular weight is calculated from the measured OH value.

[0076] In a preferred alternative embodiment, the alternative polyether is a polyether polyol having an average hydroxyl functionality of 2 to 8 and a number-average molecular weight of 150 g / mol to less than 500 g / mol, preferably an average hydroxyl functionality of 2 to 8 and a number-average molecular weight of 200 g / mol to 400 g / mol, wherein the number-average molecular weight is calculated from the measured OH value. These alternative polyether polyols are also obtained by reacting an epoxide with an H-functional initiator compound in the presence of an acidic, basic, and / or organometallic catalyst. These organometallic catalysts are, for example, bimetallic cyanide catalysts (DMC).

[0077] Suitable alternative polyether polyols are poly(oxypropylene) polyols, poly(oxypropylene-ethylene) polyols, polytetramethylene ether glycols, and block copolymers containing poly(oxy)ethylene, poly(oxy)propylene, and / or poly(oxy)butene blocks, such as poly(oxy)ethylene-poly(oxy)propylene block copolymers with terminal poly(oxy)ethylene blocks. Additionally, tripropylene glycol, triethylene glycol, tetrapropylene glycol, tetraethylene glycol, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, and monoalkyl and dialkyl ethers of glycols and poly(alkylene glycols) are also suitable.

[0078] In a particularly preferred alternative embodiment, the alternative polyether polyol is polypropylene glycol and / or polyethylene glycol having a number-average molecular weight of 150 g / mol to less than 500 g / mol, wherein the number-average molecular weight is calculated from the measured OH value.

[0079] In one embodiment of the method according to the invention, a mixing nozzle (e.g., a smooth jet nozzle, a Levos nozzle, a Bosch nozzle, etc.), preferably a jet disperser as described in patent application WO 01 / 39883 A1, is used to prepare the DMC catalyst dispersion.

[0080] Therefore, compared with known industrial methods, the preparation method of DMC catalyst dispersions can be implemented with comparable simple device structure, low shear energy consumption, good temperature control and equally good scalability, thereby achieving simple implementation in existing DMC catalyst preparation methods, such as in loop reactions.

[0081] The basic structure and operating mode of a suitable mixing nozzle should be described below. Figure 1 This diagram illustrates the structure of a simple, smooth jet nozzle. The reactant stream 1 is first accelerated in nozzle 3 and injected at a high velocity into the slowly flowing reactant stream 2. During this process, reactant stream 2 accelerates while reactant stream 1 decelerates. A portion of the kinetic energy of reactant jet 1 is converted into heat during this process and is therefore no longer available for mixing. The two reactant streams are subsequently mixed by turbulent decay in the resulting jets within vortices of varying sizes (vortex cascades). Compared to stirred tanks, this method significantly reduces the concentration gradient much faster, resulting in a significantly larger and more uniform power density. The average power density P is calculated here using the following formula:

[0082]

[0083] Where: Δp: Pressure drop in the nozzle

[0084] Volumetric flow rate

[0085] Volume of nozzle orifice

[0086] The use of such a nozzle is referred to as Method 1 below.

[0087] In a smooth jet nozzle, the first reactant stream is first accelerated within the nozzle and injected at a high velocity into the slow-flowing second reactant stream. The two reactant streams are then mixed by turbulent decay within vortices of varying sizes in the resulting jet (vortex cascade). Compared to stirred tanks, this method significantly reduces concentration gradients much faster, resulting in a significantly larger and more uniform power density.

[0088] For the method according to the invention, it is preferred to use, such as Figure 2 or Figure 3 The jet disperser shown is an example of a jet disperser that can be constructed. Figure 2The jet disperser is designed such that two nozzles 5 and 6 are arranged sequentially. The reactant flow 1 is first greatly accelerated in nozzle 5 by cross-sectional contraction. During this process, the accelerated jet draws in a second component due to the high flow rate. The nozzle spacing is preferably chosen so that only nucleation occurs in mixing chamber 4 due to the short residence time, without crystal growth. The decisive factor in the optimal design of the jet disperser is therefore the nucleation rate of the solids. Advantageously, a residence time of 0.0001 s to 0.15 s, preferably 0.001 s to 0.1 s, is set. Crystal growth occurs only in outlet 3. The diameter of nozzle 6 should preferably be chosen so that the partially mixed reactant flow is further accelerated there. Due to the additional shear force generated in nozzle 6, a uniform mixing state is achieved in a shorter time by faster vortex decay compared to method 1. Thus, compared to method 1, even in the case of precipitation reactions with extremely high nucleation rates, an ideal mixing state of the reactants can be achieved, so that the defined stoichiometric composition can be set during the precipitation reaction. Pressure drop in nozzles ranging from 0.1 bar to 1000 bar or 1*10 7 W / m 3 Up to 1*10 13 W / m 3 At power densities of 5000 µm to 50 µm, preferably 2000 µm to 200 µm, nozzle diameters have proven advantageous. This mixing operation is referred to below as Method 2.

[0089] Depending on the desired particle size, an additional n nozzles (where n = 1 - 5) can be connected downstream to obtain a multi-stage jet disperser. Figure 3 This multi-stage jet disperser is shown. The dispersed material is then guided through nozzle 7 again after nozzle 6. The design of the nozzle diameter, applicable to nozzle 6, also applies here.

[0090] Compared to method 2, the additional advantage of the additional disperser is that the formed particles can be mechanically pulverized by the large shear force in the nozzle. This can produce particles with a diameter of 10 µm to 0.1 µm. Instead of multiple nozzles in series, pulverization can also be achieved by circulating the dispersion. The use of such nozzles is specified below as method 3.

[0091] Energy dissipation in the nozzle and heating of the dispersion can occur through crystallization enthalpy. Since temperature can have a significant impact on the crystal formation process, the heat transfer device can be installed downstream of the mixing element for an isothermal process mode.

[0092] For example, scaling up without problems can be achieved by using a larger number of orifices, paralleling multiple mixing elements, or increasing the free nozzle area. However, increasing the free nozzle area cannot be achieved by increasing the nozzle diameter, as this leads to a core flow, resulting in poor mixing results. For nozzles with large free nozzle areas, slits with corresponding areas are therefore preferred.

[0093] According to the present invention, a mixing nozzle, preferably a jet disperser, is used in step i) to prepare the DMC catalyst dispersion. Examples of suitable apparatus are shown below. Figure 4 and 5 middle. Figure 4 This demonstrates a semi-batch process using a circulating reactor. Figure 5 This demonstrates a continuous method for preparing DMC catalyst dispersions.

[0094] By using mixing nozzles, especially jet dispersers, the preparation of DMC catalyst dispersions can be carried out with comparable simplicity of device structure, low shear energy consumption, good temperature control and equally good scalability compared to known industrial methods, thus enabling simple implementation in existing DMC catalyst preparation methods, such as in loop reactions.

[0095] In the method according to the present invention, the preparation of the bimetallic cyanide catalyst (DMC) includes...

[0096] i) A reaction of an aqueous solution of a cyanide-free metal salt, an aqueous solution of a basic metal cyanide salt, an organic complexing ligand, and optionally a complex-forming component, wherein the basic metal cyanide salt used has an alkalinity between 0.700 wt% and 3.000 wt% sodium hydroxide (NaOH) based on the total weight of the basic metal cyanide salt used, determined by titration as disclosed in the experimental section.

[0097] (ii) Optionally, in the second step, the solid is separated from the dispersion obtained from (i);

[0098] (iii) Optionally, in the third step, the separated solids are washed with an aqueous solution of an organic complexing ligand by means of a filter cake washing operation;

[0099] (iv) and optionally, in the fourth step, the resulting solid is dried.

[0100] A chemically calculated excess (at least 50 mol% based on the basic metal cyanide salt) of a cyanide-free metal salt, such as an aqueous solution of zinc chloride, and an aqueous solution of a basic metal cyanide salt, such as basic potassium hexacyanocobaltate, is preferably first reacted in the presence of an organic complexing ligand (which may be, for example, tert-butanol) and optionally in the presence of a metal hydroxide, metal carbonate, and / or metal oxide according to the invention, to form a dispersion. In one embodiment of the invention, such a DMC catalyst dispersion is prepared using a mixing nozzle, preferably a jet disperser.

[0101] In one embodiment of the method according to the invention, the reaction in step i) is carried out in the presence of the metal hydroxide, metal carbonate and / or metal oxide according to the invention.

[0102] In one embodiment of the method according to the invention, for the reaction in step i), 0.2 to 1.0 moles, preferably 0.3 to 0.7 moles, of basic equivalent metal hydroxide, metal carbonate, and / or metal oxide are used based on 1 mole of basic metal cyanide salt used for catalyst synthesis.

[0103] The following describes the relationship with circulating reactors (based on...) Figure 4 A DMC catalyst dispersion is prepared in a semi-batch process using a jet disperser. In this case, an aqueous solution of a cyanide-free metal salt can be circulated from container B2 and an aqueous solution of an alkaline metal cyanide can be metered in from container B1, or vice versa. When these two streams are combined in mixing element M, a dispersion of the DMC compound is formed. The dispersion of the DMC compound can be prepared by method 1, 2, or 3, preferably by method 2 or 3. The advantage of these methods is the possibility of achieving a constant reactant ratio throughout the precipitation process.

[0104] Preferably, the dispersion formed after sedimentation is circulated through a jet disperser for several minutes to several hours.

[0105] Here, when the pressure drop in the nozzle is between 0.1 bar and 1000 bar, the nozzle diameter is preferably between 2000 µm and 200 µm.

[0106] The organic complex ligand may be present in aqueous solutions of cyanide-free metal salts and / or basic metal cyanide salts, or directly metered into the dispersion obtained after precipitation of the bimetallic cyanide compound (via container B1 or B2).

[0107] Metal hydroxides, metal carbonates, and / or metal oxides may, in this case, be present in an aqueous solution of a cyanide-free metal salt and / or an aqueous solution of a basic metal cyanide salt, or be directly metered and added to the dispersion obtained after precipitation of the bimetallic cyanide compound (via container B1 or B2). Preferably, the metal hydroxides, metal carbonates, and / or metal oxides are present in an aqueous solution of a cyanide-free metal salt.

[0108] In a preferred embodiment of the method according to the invention, the organic complex ligand and the metal hydroxide, metal carbonate and / or metal oxide are present in an aqueous solution of a cyanide-free metal salt.

[0109] Preferably, other components forming the complex are then metered into the dispersion circulating through the jet disperser via container B1 or B2. The components forming the complex are preferably used herein in the form of a mixture of water and organic complexing ligands.

[0110] The metered addition of the components forming the complex into the loop and subsequent recirculation are preferably carried out under a pressure drop of 0.001 bar to 10 bar in a nozzle. According to the invention, it can also be carried out in a manner similar to... Figure 5 The example illustrates a continuous process for preparing DMC catalyst dispersions. Aqueous solutions of cyanide-free metal salts and basic metal cyanide salts are reacted in mixing element M1 according to method 1, 2, or 3 to form the dispersion. Organic complexing ligands, as well as metal hydroxides, metal carbonates, and / or metal oxides, may be present in the aqueous solutions of cyanide-free metal salts and / or basic metal cyanide salts. In this case, [the following is omitted] Figure 5 The mixing stage M2 is used. Organic complexing ligands and metal hydroxides, metal carbonates, and / or metal oxides may also be added via mixing element M2 after the bimetallic cyanide compound has precipitated. To increase the residence time of the dispersion, it may be circulated via mixing element M2. The components forming the complex—preferably in the form of a mixture of water and organic complexing ligands—may subsequently be added to mixing element M3 and circulated again to increase the residence time.

[0111] In a preferred embodiment of the method according to the invention, the process temperature of the dispersion in the reaction of step i) is between 25°C and 75°C, preferably between 30°C and 70°C, particularly preferably between 35°C and 65°C, and very particularly preferably between 40°C and 60°C. Here, the process temperature corresponds to... Figure 4 The process temperature in container B2.

[0112] In a preferred embodiment of the method according to the invention, in the second step (ii), the solid is separated from the dispersion obtained from (i).

[0113] The solids (i.e., the precursors of the catalyst according to the invention) are separated from the dispersion using known techniques such as centrifugation or filtration. Suitable filtration devices are described, for example, in "Ullmann's Encyclopedia of Industrial Chemistry", Volume B2, Chapters 9 and 10, VCH, Weinheim, 1988 and in H. Gasper, D. Oechsle, E. Pongratz (ed.): "Handbuch der industriellen Fest / Flüssig-Filtration", Wiley-VCH Verlag GmbH, Weinheim, 2000.

[0114] The pressure gradient required for filtration can be applied by gravity, by centrifugal force (e.g., a filter centrifuge), preferably by gas pressure difference (e.g., a vacuum filter or pressure filter), or by liquid pressure (e.g., a filter press, drum or disc filter, and possibly a cross-flow filter module).

[0115] To separate the catalyst, both discontinuous and continuous filtration devices can be used. Examples of discontinuous filtration devices include scraper-discharge centrifuges and bag-turning centrifuges, membrane, box, frame, or tubular filter presses, automatic filter presses, automatic extrusion devices, plate, drum, and tubular filters, as well as vacuum and pressure suction filters. Examples of continuous filtration devices include belt filter presses, pressure and vacuum drum filters, pressure and vacuum disc filters, belt filters, and cross-flow filters.

[0116] For filtering DMC catalyst dispersions, vacuum or pressure filters or vacuum or pressure suction filters are particularly suitable at the laboratory scale; pressure suction filters, filter presses, and automatic filter presses are particularly suitable at the pilot and production scales.

[0117] Membrane filter presses have proven particularly suitable in pilot and pilot-scale operations. With the aid of a suitable filter cloth, preferably a membrane cloth, they are able to filter DMC catalyst dispersions due to the applied liquid pressure gradient.

[0118] Filtration is typically carried out at temperatures between 10 and 80°C. The applied pressure differential can be from 0.001 bar to 200 bar, preferably from 0.1 bar to 100 bar, and particularly preferably from 0.1 bar to 25 bar, wherein the applied pressure differential depends on the apparatus used.

[0119] The separated solids obtained in step (ii) can be washed by redispersion or filter cake washing.

[0120] In a preferred embodiment of the method according to the invention, in the third step (iii), the separated solids are washed with an aqueous solution of an organic complexing ligand by means of filter cake washing.

[0121] Filter cake washing is preferably performed by pulping or, more preferably, by flow-through washing. Here, the washing liquid flows through the filter cake and displaces the liquid previously contained within it, during which the diffusion effect also begins to take effect. Moisture removal from the washed filter cake can be achieved by gas pressure differential, centrifugal force, or mechanical pressing, or preferably a combination of gas pressure differential removal followed by mechanical pressing. The pressure used for mechanical pressing can be applied mechanically or via a membrane.

[0122] Filter cake washing simplifies and thus accelerates the preparation process. The preferred ratio of washing liquid to filter cake volume is the amount that achieves complete exchange of the liquid present in the original filter cake.

[0123] In an alternative preferred embodiment of the method according to the invention, the separated solids are then washed in a third process step with an aqueous solution of the organic complexing ligand (e.g., by redispersion and subsequently by filtration or centrifugation). This makes it possible to remove, for example, water-soluble byproducts such as potassium chloride from the catalyst according to the invention. The amount of the organic complexing ligand in the aqueous washing solution is preferably between 40% and 80% by weight based on the total solution.

[0124] Optionally, in the third step, the component that forms the complex may be added to the aqueous washing solution, preferably in the range of 0.5% to 5% by weight based on the total solution.

[0125] It is also advantageous to wash the separated solids more than once. Preferably, in the first washing step (iii-1), washing is performed with an aqueous solution of the organic complexing ligand (e.g., by redispersion and subsequent separation by filtration or centrifugation) to thereby remove, for example, water-soluble byproducts such as potassium chloride from the catalyst according to the invention. Particularly preferred is that the amount of organic complexing ligand in the aqueous washing solution is between 40% and 80% by weight based on the total solution from the first washing step. In a further washing step (iii-2), the first washing step is repeated once or more, preferably 1 to 3 times, or preferably a non-aqueous solution, such as a mixture or solution of the organic complexing ligand and the complex-forming component (preferably between 0.5% and 5% by weight based on the total washing solution from step (iii-2)) (preferably between 1% and 20% by weight based on the total washing solution from step (iii-2)), is used as the washing solution to wash the solids once or more, preferably 1 to 3 times.

[0126] In a preferred embodiment of the method according to the invention, in the fourth step (iv), the resulting solid is subsequently dried.

[0127] Here, the separated and optionally washed solids are optionally pulverized and then dried at a temperature typically 20-100°C and a pressure typically 0.1 mbar to standard pressure (1013 mbar).

[0128] In a preferred embodiment of the method according to the invention, steps (ii) and (iii) are performed in a filter press.

[0129] It has proven advantageous to squeeze the washed filter cake under a pressure of 0.5 to 200 bar, preferably at the highest possible pressure, after washing. This can be done, for example, directly in a filter press after washing or by means of other suitable squeezing devices (capable of applying mechanical pressure to allow the liquid present in the filter cake to escape through a membrane or suitable filter cloth). Mechanical removal of water from the filter cake, preferably before drying, after washing, can preferably be carried out in a filter press, preferably by mechanical squeezing with pressure applied to the membrane. Mechanical removal of water preferably results in the most substantial removal of washing liquid from the filter cake.

[0130] The DMC catalyst is then dried at a temperature of approximately 20 to 100°C and a pressure of approximately 0.1 mbar to standard pressure (10¹³ mbar). Contact dryers, convection dryers, and spray dryers are suitable for this purpose. Preferably, drying is also carried out directly in apparatus for mechanically separating the liquid, if these are suitable (e.g., suction dryers, centrifugal dryers, "hot presses").

[0131] In a particularly preferred embodiment of the method according to the invention, steps (ii), (iii), and (iv) are carried out in a heatable filter press.

[0132] A heated filter press is preferably used in this method. This is constructed similarly to a conventional filter press with a membrane packing. The difference in design between the membrane plates used and conventional plates is that the heating medium can flow through the space behind the membrane. Liquid-tight (so-called "drip-proof" or "airtight") membrane filter plates are preferred.

[0133] The heated medium flows behind the filter cake (which is completely separated from it by the filter membrane and the filter medium) and heats the filter cake in the process. The pressurizing medium is at a sufficiently high pressure to ensure that the membrane is in contact with the filter cake. The filter cake can be heated on one or both sides. Heating on both sides is advantageous, considering the drying time.

[0134] A vacuum is applied to the filtrate side to aid the drying process. This vacuum can be generated, for example, by a liquid ring pump. The drawn-off vapor stream is cooled upstream of the vacuum pump to condense volatile components (e.g., tert-butanol and water). The measured and controlled variables are the amount of condensate, the pressure in the filtrate system of the compressor, and the filter cake temperature.

[0135] In this method, the membrane pressurization pressure is preferably from 0.1 bar to 10 bar. The temperature of the pressurizing and heating media is from 30°C to 80°C, preferably from 40°C to 60°C. The filtrate-side pressure is preferably less than 100 mbar. Such a high flow rate of the heating media should be chosen to ensure good heat transfer between the heating media and the product. The drying time is typically from a few minutes to several hours, usually 1 to 10 hours. This type of drying reliably achieves a residual moisture content below the target value of approximately 5%.

[0136] In a further process step, the product from which minor components have been separated and removed can be ground and packaged.

[0137] Another subject of the present invention is a DMC catalyst prepared by the method according to the invention.

[0138] Another subject of the invention is the use of the DMC catalyst prepared by the method according to the invention in the preparation of polyoxyethylene polyols, preferably polyether polyols prepared by polymerization of epoxides onto initiator compounds having active hydrogen atoms and / or polyether carbonate polyols prepared by polymerization of epoxides onto initiator compounds having active hydrogen atoms in the presence of carbon dioxide.

[0139] The DMC catalysts prepared by the method of the present invention can typically be used at very low concentrations (25 ppm and lower, based on the amount of polyoxyethylene polyol, preferably polyether polyol, to be prepared) due to their extremely high activity. If the polyoxyethylene polyol, preferably polyether polyol, prepared in the presence of the DMC catalyst prepared by the method of the present invention is used to prepare polyurethane, the removal of the catalyst from the polyoxyethylene polyol, preferably polyether polyol, can be omitted without adversely affecting the product quality of the resulting polyurethane. Example

[0140] The OH value was determined according to the procedure in DIN 53240. The viscosity was determined by rotational viscometer (PhysicaMCR 51, manufacturer: Anton Paar) according to the procedure in DIN 53018.

[0141] The alkalinity (as wt% sodium hydroxide (NaOH)) of the basic metal cyanide salt used was determined at 25 °C by titration with HCl (0.1 mol / L) on a 24 wt% aqueous solution.

[0142] Preparation of DMC catalyst:

[0143] Example 1 (Comparative):

[0144] Use according to WO 01 / 39883 A1 Figure 4 The apparatus is used to prepare catalysts.

[0145] In containing according to WO 01 / 39883 A1 Figure 2 In a circulating reactor with a jet disperser having orifices (0.7 mm in diameter), in step i), at 50°C (in WO 01 / 39883 A1) Figure 4 (Measured in container D2) A solution of 258 g zinc chloride and 1.43 g NaOH (0.46 mol (NaOH) / 1 mol (Khex)) in 937 g distilled water and 135 g tert-butanol was circulated. A solution of 26 g potassium hexacyanocobaltate (Khex) with an alkalinity of 0.400 wt% NaOH in 332 g distilled water was then metered in. The pressure drop in the jet disperser was 2.9 bar. Subsequently, the resulting dispersion was circulated for 60 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser. Afterward, a mixture of 5.7 g tert-butanol, 159 g distilled water, and 27.6 g polypropylene glycol 1000 (PPG-1000) was metered in, and the dispersion was then circulated for 80 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser.

[0146] The 230 g dispersion was obtained in a 20 cm² area. 3 The filter cake was filtered in a pressure suction filter with a filter area of ​​[missing information] (step ii) and then washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000 (step iii). The washed filter cake was mechanically squeezed between two filter papers and finally dried at 60 °C under a high vacuum of approximately 0.05 bar (absolute) for 2 hours (step iv). The theoretical total basicity of the DMC catalyst was 1.534 g (NaOH), which is the sum of the mass of the basicity of the potassium hexacyanocobaltate (Khex) used (0.104 g (NaOH)) and the mass of the sodium hydroxide used in step i) (1.43 g).

[0147] Example 2 (Comparative):

[0148] In containing according to WO 01 / 39883 A1 Figure 2 In a circulating reactor with a jet disperser having orifices (0.7 mm in diameter), in step i), at 50°C (in WO 01 / 39883 A1) Figure 4(Measured in container D2) A solution of 258 g zinc chloride and 1.36 g NaOH (0.43 mol (NaOH) / 1 mol (Khex)) in 937 g distilled water and 135 g tert-butanol was circulated. A solution of 26 g potassium hexacyanocobaltate in 332 g distilled water with an alkalinity of 0.660 wt% NaOH was then metered into the solution. The pressure drop in the jet disperser was 2.9 bar. The resulting dispersion was then circulated for 60 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser. Subsequently, a mixture of 5.7 g tert-butanol, 159 g distilled water, and 27.6 g polypropylene glycol 1000 (PPG-1000) was metered into the solution, and the dispersion was then circulated for 80 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser.

[0149] The 230 g dispersion was obtained in a 20 cm² area. 3 The filter cake was filtered in a pressure suction filter with a filter area of ​​[missing information] (step ii) and then washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000 (step iii) (step iii). The washed filter cake was mechanically squeezed between two filter papers and finally dried at 60 °C under a high vacuum of approximately 0.05 bar (absolute) for 2 hours (step iv) (step iv). The theoretical total basicity of the DMC catalyst was 1.532 g (NaOH), which is the sum of the mass of the basicity of the potassium hexacyanocobaltate (Khex) used (0.172 g (NaOH)) and the mass of the sodium hydroxide used in step i) (1.36 g).

[0150] Example 3:

[0151] In containing according to WO 01 / 39883 A1 Figure 2 In a circulating reactor with a jet disperser having orifices (0.7 mm in diameter), in step i), at 50°C (in WO 01 / 39883 A1) Figure 4 (Measured in container D2) A solution of 258 g zinc chloride and 1.31 g NaOH (0.42 mol (NaOH) / 1 mol (Khex)) in 937 g distilled water and 135 g tert-butanol was circulated. A solution of 26 g potassium hexacyanocobaltate in 332 g distilled water with an alkalinity of 0.855 wt% NaOH was then metered into the solution. The pressure drop in the jet disperser was 2.9 bar. The resulting dispersion was then circulated for 60 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser. Subsequently, a mixture of 5.7 g tert-butanol, 159 g distilled water, and 27.6 g polypropylene glycol 1000 (PPG-1000) was metered into the solution, and the dispersion was then circulated for 80 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser.

[0152] The 230 g dispersion was obtained in a 20 cm² area. 3 The filter cake was filtered in a pressure suction filter with a filter area of ​​[missing information] (step ii) and then washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000 (step iii). The washed filter cake was mechanically squeezed between two filter papers and finally dried at 60 °C under a high vacuum of approximately 0.05 bar (absolute) for 2 hours (step iv). The theoretical total basicity of the DMC catalyst was 1.532 g (NaOH), which is the sum of the mass of the basicity of the potassium hexacyanocobaltate (Khex) used (0.222 g (NaOH)) and the mass of the sodium hydroxide used in step i) (1.31 g).

[0153] Example 4:

[0154] In containing according to WO 01 / 39883 A1 Figure 2 In a circulating reactor with a jet disperser having orifices (0.7 mm in diameter), in step i), at 50°C (in WO 01 / 39883 A1) Figure 4 (Measured in container D2) A solution of 258 g zinc chloride and 1.26 g NaOH (0.40 mol (NaOH) / 1 mol (Khex)) in 937 g distilled water and 135 g tert-butanol was circulated. A solution of 26 g potassium hexacyanocobalaminate in 332 g distilled water with an alkalinity of 1.067 wt% NaOH was then metered into the solution. The pressure drop in the jet disperser was 2.9 bar. Subsequently, the resulting dispersion was circulated for 60 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser. Afterward, a mixture of 5.7 g tert-butanol, 159 g distilled water, and 27.6 g polypropylene glycol 1000 (PPG-1000) was metered into the solution, and the dispersion was then circulated for 80 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser.

[0155] The 230 g dispersion was obtained in a 20 cm² area. 3 The filter cake was filtered in a pressure suction filter with a filter area of ​​[missing information] (step ii) and then washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000 (step iii). The washed filter cake was mechanically squeezed between two filter papers and finally dried at 60 °C under a high vacuum of approximately 0.05 bar (absolute) for 2 hours (step iv). The theoretical total basicity of the DMC catalyst was 1.537 g (NaOH), which is the sum of the mass of the basicity of the potassium hexacyanocobaltate (Khex) used (0.277 g (NaOH)) and the mass of the sodium hydroxide used in step i) (1.26 g).

[0156] Example 5:

[0157] In containing according to WO 01 / 39883 A1 Figure 2 In a circulating reactor with a jet disperser having orifices (0.7 mm in diameter), in step i), at 50°C (in WO 01 / 39883 A1) Figure 4 (Measured in container D2) A solution of 258 g zinc chloride and 1.20 g NaOH (0.38 mol (NaOH) / 1 mol (Khex)) in 937 g distilled water and 135 g tert-butanol was circulated. A solution of 26 g potassium hexacyanocobalaminate in 332 g distilled water with an alkalinity of 1.279 wt% NaOH was then metered into the solution. The pressure drop in the jet disperser was 2.9 bar. The resulting dispersion was then circulated for 60 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser. Subsequently, a mixture of 5.7 g tert-butanol, 159 g distilled water, and 27.6 g polypropylene glycol 1000 (PPG-1000) was metered into the solution, and the dispersion was then circulated for 80 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser.

[0158] The 230 g dispersion was obtained in a 20 cm² area. 3 The filter cake was filtered in a pressure suction filter with a filter area of ​​[missing information] (step ii) and then washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000 (step iii). The washed filter cake was mechanically squeezed between two filter papers and finally dried at 60 °C under a high vacuum of approximately 0.05 bar (absolute) for 2 hours (step iv). The theoretical total basicity of the DMC catalyst was 1.533 g (NaOH), which is the sum of the mass of the basicity of the potassium hexacyanocobalaminate (Khex) used (0.333 g (NaOH)) and the mass of the sodium hydroxide used in step i) (1.20 g).

[0159] Example 6:

[0160] In containing according to WO 01 / 39883 A1 Figure 2 In a circulating reactor with a jet disperser having orifices (0.7 mm in diameter), in step i), at 50°C (in WO 01 / 39883 A1) Figure 4(Measured in container D2) A solution of 258 g zinc chloride and 1.10 g NaOH (0.35 mol (NaOH) / 1 mol (Khex)) in 937 g distilled water and 135 g tert-butanol was circulated. A solution of 26 g potassium hexacyanocobalaminate in 332 g distilled water with an alkalinity of 1.690 wt% NaOH was then metered into the solution. The pressure drop in the jet disperser was 2.9 bar. The resulting dispersion was then circulated for 60 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser. Subsequently, a mixture of 5.7 g tert-butanol, 159 g distilled water, and 27.6 g polypropylene glycol 1000 (PPG-1000) was metered into the solution, and the dispersion was then circulated for 80 minutes at 50 °C and a pressure drop of 2.9 bar in the jet disperser.

[0161] The 230 g dispersion was obtained in a 20 cm² area. 3 The filter cake was filtered in a pressure suction filter with a filter area of ​​[missing information] (step ii) and then washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000 (step iii). The washed filter cake was mechanically squeezed between two filter papers and finally dried at 60 °C under a high vacuum of approximately 0.05 bar (absolute) for 2 hours (step iv). The theoretical total basicity of the DMC catalyst was 1.539 g (NaOH), which is the sum of the mass of the basicity of the potassium hexacyanocobaltate (Khex) used (0.439 g (NaOH)) and the mass of the sodium hydroxide used in step i) (1.10 g).

[0162] Catalyst test ("8K glycol stress test"):

[0163] DMC catalysts were tested in a so-called "8K glycol stress test." Here, a polypropylene glycol ("8K glycol") with a calculated OH value of 14 mg KOH / g, i.e., a molecular weight of 8000 g / mol, was prepared using a bifunctional polypropylene glycol initiator ("Arcol Polyol 725" from Covestro") with an OH value of 147 mg KOH / g, under short propylene oxide stoichiometric time (30 minutes). In this test, the decisive criterion for evaluating catalyst quality / activity is the viscosity of the resulting polyol, with DMC catalysts exhibiting improved quality / activity producing lower 8K glycol viscosities.

[0164] General implementation:

[0165] 75 g of bifunctional polypropylene glycol initiator (OH value = 147 mg KOH / g) and 30.7 mg of DMC catalyst were initially loaded into a 1 L stainless steel reactor. After 5 cycles of nitrogen / vacuum exchange between 0.1 and 3.0 bar (absolute), the reactor contents were heated to 130 °C with stirring (800 rpm). The mixture was then stripped with nitrogen at 100 mbar (absolute) for 30 min at 130 °C. 7.5 g of propylene oxide was then added at 100 mbar (absolute) to activate the catalyst. Catalyst activation was manifested as an accelerated pressure drop in the reactor. After catalyst activation, the remaining propylene oxide (685.7 g) was metered in over 30 min at 130 °C with stirring (800 rpm). After a post-reaction time of 30 min at 130 °C, volatile components were distilled off at 90 °C under vacuum (< 10 mbar) for 30 min. The product is then cooled to room temperature and removed from the reactor.

[0166] Measure the OH value and viscosity (25℃) of the obtained product. If the measured OH value deviates from the calculated OH value (14 mg KOH / g), determine the "corrected viscosity" from the measured viscosity using the following formula:

[0167] Corrected viscosity (25℃) = Measured viscosity (25℃) + 659 * (OH value – 14)

[0168] The results of the catalyst tests in the "8K glycol stress test" are summarized in Table 1.

[0169] Table 1:

[0170] Catalyst Tests / Examples DMC catalyst / Examples Khex alkalinity [wt% NaOH] / [mol(NaOH) / mol(Khex)] <![CDATA[n(NaOH in step i) / n(Khex) [mol / mol] a) > <![CDATA[Total theoretical alkalinity [g (NaOH)] b) > OH value [mgKOH / g] Viscosity at 25℃ / Measured [mPas] Viscosity at 25℃ / Corrected [mPas] 7 (Comparison) 1 (Comparison) 0.400 / 0.033 0.46 1.534 14.0 5765 5765 8 (Comparison) 2 (Comparison) 0.660 / 0.055 0.43 1.532 13.7 5820 5622 9 3 0.855 / 0.072 0.42 1.532 13.9 5100 5034 10 4 1.067 / 0.090 0.40 1.537 14.3 4745 4943 11 5 1.279 / 0.108 0.38 1.533 14.0 4940 4940 12 6 1.690 / 0.143 0.35 1.539 14.0 5095 5095

[0171] a) The sodium hydroxide (NaOH) added in step i) is calculated as the base equivalent based on 1 mole of basic potassium hexacyanocobaltate (Khex) used as a basic metal cyanide salt in the catalyst synthesis.

[0172] b) The theoretical total basicity of the DMC catalyst, calculated as [g NaOH], where this mass is the sum of the mass of the basicity of the potassium hexacyanocobalaminate (Khex) used [g (NaOH)] and the mass of the sodium hydroxide used in step i).

[0173] The results showed that the DMC catalyst prepared using basic potassium hexacyanocobaltate (Khex) with an alkalinity between 0.700 wt% and 3.000 wt% NaOH at the same theoretical total alkalinity as the DMC catalyst produced a lower viscosity value in the "8K glycol stress test".

Claims

1. Process for the preparation of a double metal cyanide catalyst, comprising i) a reaction of an aqueous solution of a metal salt free of cyanide, an aqueous solution of a basic metal cyanide salt, an organic complexing ligand and a complex- forming component, wherein the metal cyanide salt is potassium hexacyanocobaltate (III), wherein the organic complexing ligand is one or more compounds selected from the group consisting of dimethoxyethane, tert-butanol, 2-methyl-3-buten-2-ol, 2-methyl-3- butyn-2-ol, ethylene glycol mono-tert-butyl ether and 3-methyl-3-oxetanemethanol, wherein the complex-forming component is a polyether, the basic metal cyanide salt used has a basicity of between 0.800 wt.-% and 1.500 wt.-% sodium hydroxide, determined by titration, in which the basicity of the basic metal cyanide salt used is determined at 25°C on a 24 wt.-% aqueous solution by titration with 0.1 mol / 1 HCI, in wt.-% sodium hydroxide, based on the total weight of the basic metal cyanide salt used. characterized in that 2. Process as claimed in claim 1, wherein the basic metal cyanide salt used contains a metal hydroxide, a metal carbonate and / or a metal oxide.

3. Process as claimed in claim 1, wherein the basic metal cyanide salt used is obtainable by adding a metal hydroxide, a metal carbonate and / or a metal oxide during the preparation of the basic metal cyanide salt.

4. Process as claimed in claim 1, wherein the basic metal cyanide salt used is obtainable by reaction of a metal cyanide salt with a metal hydroxide, a metal carbonate and / or a metal oxide.

5. Process as claimed in any one of claims 2 to 4, wherein one or more metals of the first or second main group of the periodic table are comprised as metal hydroxide, metal carbonate and / or metal oxide.

6. Process as claimed in any one of claims 2 to 4, wherein the metal hydroxide, metal oxide and / or metal carbonate is one or more compounds selected from the group consisting of sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, calcium oxide, calcium hydroxide, barium hydroxide and barium oxide.

7. Process as claimed in claim 1 or 2, wherein the reaction in step i) is carried out in the presence of a metal hydroxide, a metal carbonate and / or a metal oxide, wherein the metal hydroxide, metal carbonate and / or metal oxide comprises one or more metals of the first or second main group of the periodic table.

8. Process as claimed in claim 1 or 2, wherein the reaction in step i) is carried out in the presence of a metal hydroxide, a metal carbonate and / or a metal oxide, wherein the metal hydroxide, metal oxide and / or metal carbonate is one or more compounds selected from the group consisting of sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, calcium oxide, calcium hydroxide, barium hydroxide and barium oxide. ​ 9. The process according to claim 1 or 2, wherein for the reaction in step i) 0.2 to 1.0 molar equivalents of a metal hydroxide, metal carbonate and / or metal oxide are used, wherein the molar equivalents are based on 1 mole of the basic metal cyanide salt used for the synthesis of the catalyst, wherein the metal hydroxide, metal carbonate and / or metal oxide comprises one or more metals of the first or second main group of the periodic table.

10. The process according to claim 1 or 2, wherein for the reaction in step i) 0.2 to 1.0 molar equivalents of a metal hydroxide, metal carbonate and / or metal oxide are used, wherein the molar equivalents are based on 1 mole of the basic metal cyanide salt used for the synthesis of the catalyst, wherein the metal hydroxide, metal oxide and / or metal carbonate is one or more compounds selected from the group consisting of sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, calcium oxide, calcium hydroxide, barium hydroxide and barium oxide.

11. The process according to claim 1 or 2, wherein for the reaction in step i) 0.3 to 0.7 molar equivalents of a metal hydroxide, metal carbonate and / or metal oxide are used, wherein the molar equivalents are based on 1 mole of the basic metal cyanide salt used for the synthesis of the catalyst, wherein the metal hydroxide, metal carbonate and / or metal oxide comprises one or more metals of the first or second main group of the periodic table.

12. The process according to claim 1 or 2, wherein for the reaction in step i) 0.3 to 0.7 molar equivalents of a metal hydroxide, metal carbonate and / or metal oxide are used, wherein the molar equivalents are based on 1 mole of the basic metal cyanide salt used for the synthesis of the catalyst, wherein the metal hydroxide, metal oxide and / or metal carbonate is one or more compounds selected from the group consisting of sodium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, calcium oxide, calcium hydroxide, barium hydroxide and barium oxide.

13. The process according to claim 1 or 2, wherein the complex forming component is a polyether polyol.

14. The process according to claim 1 or 2, wherein the organic complexing ligand is tert-butanol.

15. The process according to claim 1 or 2, wherein the reaction in step i) is carried out using a mixing nozzle.

16. The process according to claim 1 or 2, wherein the reaction in step i) is carried out using a jet disperser.

17. The double metal cyanide catalyst obtainable according to the process of any one of claims 1 to 16.

18. Use of the double metal cyanide catalyst as defined in claim 17 for the preparation of polyoxyalkylene polyols.

19. Use of the double metal cyanide catalyst as defined in claim 17 for the preparation of polyether polyols and / or polyether carbonate polyols.

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