METHOD FOR THE MANUFACTURE OF DOUBLE METAL CYANIDE CATALYTIC CONVERTERS

Description

[0001] The present invention relates to an improved process for the production of double metal cyanide (DMC) catalysts for the production of polyoxyalkylene polyols, preferably polyether polyols and / or polyether carbonate polyols. A further object is DMC catalysts obtainable by this process and the use of the catalysts according to the invention for the production of polyoxyalkylene polyols.

[0002] DMC catalysts are in principle known from the prior art (see e.g. US-A 3 404 109, US-A 3 829 505, US-A 3 941 849 and US-A 5 158 922). DMC catalysts, such as those described in US-A 5 470 813, EP-A 700 949, EP-A 743 093, EP-A 761 708, WO 97 / 40086, WO 98 / 16310, WO 00 / 47649, and WO 2021 / 165283 A1, possess very high activity in the homopolymerization of epoxides and enable the production of polyether polyols at very low catalyst concentrations (25 ppm or less), so that separation of the catalyst from the finished product ia is no longer necessary. A typical example is the highly active DMC catalysts described in EP-A 700 949, which, in addition to a double metal cyanide compound (e.g. zinc hexacyanocobaltate(III)) and an organic complex ligand (e.g. tert-butanol), also contain a polyether with a number-mean molecular weight greater than 500 g / mol.

[0003] WO 01 / 39883 A1 discloses a process for the production of double metal cyanide (DMC) catalysts for the production of polyether polyols by polyaddition of alkylene oxides to starter compounds containing active hydrogen atoms, in which the DMC catalyst dispersion is produced using a mixing nozzle, preferably a jet disperser. The DMC catalysts produced in this way exhibit increased activity, reduced particle size, and a narrower particle size distribution in the polyether polyol production process.

[0004] WO 01 / 80994 A1 also discloses a process for the production of double metal cyanide (DMC) catalysts, in which aqueous solutions of a metal salt and a metal cyanide salt are first reacted in the presence of an organic complexing ligand and optionally one or more other complexing components to form a DMC catalyst dispersion. This dispersion is then filtered, and the filter cake is subsequently washed with one or more aqueous or non-aqueous solutions of the organic complexing ligand and optionally one or more other complexing components by filter cake washing. Finally, after optional pressing or mechanical dehumidification, the washed filter cake is dried. The disclosed process reduces the time required for catalyst production, and the resulting catalysts exhibit comparable activities in the production of polyether polyols compared to reference catalysts.

[0005] EP 700 949 A2 describes a DMC catalyst containing a DMC compound, an organic complex ligand, and 5–80 wt% of a polyether with a number-average molecular weight > 500 g / mol, wherein the DMC catalyst dispersion is prepared at room temperature. The catalysts used are generally active in the production of polyether polyols.

[0006] WO 2021 / 148272 A1 discloses a process for the production of a double metal cyanide catalyst (DMC), wherein the resulting DMC catalysts exhibit increased catalytic activity in the production of polyoxyalkylene polyols, for example, in catalyst testing according to the "8K Diol Stressed Test". This process involves the reaction of an aqueous solution of a cyanide-free metal salt, an aqueous solution of a metal cyanide salt, an organic complexing ligand, and polypropylene glycol as a complexing component to form a dispersion. The reaction is carried out using a mixing nozzle, and the process temperature of the dispersion during the reaction is between 26°C and 49°C.

[0007] The objective of the present application was to provide an improved process for the production of double metal cyanide (DMC) catalysts with further increased catalytic activity in the production of polyoxyalkylene polyols, preferably polyether polyols and / or polyether carbonate polyols. This improved activity, for example, leads to a reduced product viscosity in catalyst testing during semi-batch polyol production according to the "8K Diol Stressed Test" described, for example, in WO 98 / 16310 A1, but also in continuous polyol production. The aim was thus to provide more catalytically active DMC catalysts that lead to polyoxyalkylene polyols, preferably polyether polyols and / or polyether carbonate polyols, with a reduced viscosity, thereby facilitating the further processing of the polyoxyalkylene polyols in the subsequent polyurethaneization reaction.The increased catalyst activity also allows for a reduction in the amount of catalyst used, which improves the economic efficiency of the process.

[0008] At the same time, the production process of the DMC catalyst dispersion should be carried out with a comparatively simple apparatus setup, low energy expenditure during shearing, good temperature control, and also good scalability compared to known technical processes, in order to enable simple implementation in existing DMC catalyst production processes, for example in loop reactors.

[0009] Surprisingly, it has now been found that a process for producing a double metal cyanide (DMC) catalyst comprehensive i) The reaction of an aqueous solution of a cyanide-free metal salt, an aqueous solution of a metal cyanide salt, an organic complexing ligand, and a complexing component, characterized in that the complexing component contains one or more compounds (1) of formula (I): R 1 -O-(R 2 -O) n -H (I) with R 1 a substituted or unsubstituted aryl group, R 2 an alkylene group, preferably an ethylene group or isopropylene group, particularly preferably an ethylene group (Et), and n ≥ 1, preferably 5 ≤ n ≤ 80, particularly preferably 7 ≤ n ≤ 70, most preferably 8 ≤ n ≤ 60, which solves the above-mentioned problem.

[0010] The invention is described below, wherein the embodiments according to the invention can be combined with one another as desired, unless the technical context indicates otherwise. Complexing component Connection (1)

[0011] According to the invention, the complexing component contains one or more compounds (1) of formula (I): R 1 -O-(R 2 -O) n -H (I) with R 1 of a substituted or unsubstituted aryl group, R 2 of an alkylene group, preferably an ethylene group or isopropylene group, particularly preferably an ethylene group (Et), and n ≥ 1, preferably 5 ≤ n ≤ 80, particularly preferably 7 ≤ n ≤ 70, most particularly preferably 8 ≤ n ≤ 60.

[0012] In one embodiment of the method according to the invention, R 1 has a structure according to formula (II): with R 3 , R 4 , R 5 , R 6 , R 7 independently selected from the group consisting of hydrogen linear or branched alkyl groups with 1 to 22 carbon atoms, cycloaliphatic groups containing 3 to 22 carbon atoms and substituted or unsubstituted aryl groups with 6 to 16 carbon atoms.

[0013] In a preferred embodiment of the method according to the invention, R 3 , R 5 , R 7 are independently selected from the group consisting of hydrogen, linear or branched alkyl groups with 1 to 22 carbon atoms, cycloaliphatic groups containing 3 to 22 carbon atoms and substituted or unsubstituted aryl groups with 6 to 16 carbon atoms, and R 4 and R 6 are hydrogen.

[0014] In a particularly preferred embodiment of the process according to the invention, R 3 , R 5 , R 7 are independently selected from the group consisting of linear or branched alkyl groups with 1 to 10 carbon atoms and substituted or unsubstituted aryl groups with 6 to 12 carbon atoms, and R 4 and R 6 are hydrogen.

[0015] In one embodiment of the method according to the invention, R 1 has a structure according to formula (III), (IV) or (V):

[0016] In a preferred embodiment of the method according to the invention, R 1 has a structure according to formula (III).

[0017] In one embodiment of the method according to the invention, the compound (1) has a structure according to formula (VI), (VII) and / or (VIII): with n ≥ 1, preferably 5 ≤ n ≤ 80, particularly preferably 7 ≤ n ≤ 70, most particularly preferably 8 ≤ n ≤ 60.

[0018] In a preferred embodiment of the process according to the invention, the compound (1) has a structure according to formula (VI) with 5 ≤ n ≤ 80, preferably 7 ≤ n ≤ 70 and particularly preferably 8 ≤ n ≤ 60, wherein this compound (VI) is also referred to as tri-sec.-butylphenol ethoxylate with 5 to 80, preferably 7 to 70 and particularly preferably with 8 to 60 ethoxy units. Connection (2)

[0019] In one embodiment of the process according to the invention, the complexing component contains, in addition to compound (1), one or more compounds (2), wherein compound (2) is composed of the following classes of compounds: polyethers, polyesters, polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycol glycidyl ethers, polyacrylamide, poly(acrylamide-co-acrylic acid), polyacrylic acid, poly(acrylic acid-co-maleic acid), polyacrylonitrile, polyalkyl acrylates, polyalkyl methacrylates, polyvinyl methyl ethers, polyvinyl ethyl ethers, 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 polymers, polyalkyleneimines, maleic acid and maleic anhydride copolymers, hydroxyethylcellulose and polyacetals, or glycidyl ethers, glycosides, carboxylic acid esters of polyhydric alcohols, esters or amides. Cyclodextrins or phosphorus compounds can be selected.

[0020] In the process according to the invention for the production of the DMC catalysts, polyethers are preferably used as compound (2).

[0021] 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 determined OH number.

[0022] The OH numbers are determined according to the regulations of DIN 53240.

[0023] Suitable polyethers include those produced by ring-opening polymerization of cyclic ethers, such as oxetane and tetrahydrofuran polymers. Any catalysis is possible for this reaction. The polyether must have suitable end groups, such as hydroxyl, amine, ester, or ether end groups.

[0024] In a particularly preferred embodiment, the polyether has an average hydroxyl functionality of 2 to 8 and a number-average molecular weight in the range of 500 g / mol to 10,000 g / mol, preferably from 700 g / mol to 5,000 g / mol, wherein the number-average molecular weight is calculated from the determined OH number.

[0025] In In a particularly preferred embodiment, the polyether polyols are obtained by reacting alkylene oxides and H-functional starter compounds in the presence of acidic, basic, and / or organometallic catalysts. These organometallic catalysts are, for example, double metal cyanide (DMC) catalysts.

[0026] Suitable polyether polyols are poly(oxypropylene) polyols, poly(oxypropylenoxyethylene) polyols, polytetramethylene ether glycols, and block copolymers containing poly(oxy)ethylene, poly(oxy)propylene and / or poly(oxy)butylene blocks, such as poly(oxy)ethylene-poly(oxy)propylene block copolymers with terminal poly(oxy)ethylene blocks.

[0027] In In a preferred embodiment, the polyether polyol is a poly(oxypropylene) polyol with a number-average molecular weight of ≥ 500 g / mol, wherein the number-average molecular weight is calculated from the determined OH number.

[0028] In a particularly preferred embodiment, the polyether polyol is a poly(oxypropylene) polyol, preferably a poly(oxypropylene)diol and / or a poly(oxypropylene)triol with a number-average molecular weight of 700 g / mol to 4000 g / mol, wherein the number-average molecular weight is calculated from the determined OH number.

[0029] In an alternative embodiment, the polyethers have an average hydroxyl functionality of 2 to 8 and a number-average molecular weight in the range of 150 g / mol to less than 500 g / mol, preferably from 200 g / mol to 400 g / mol, wherein the number-average molecular weight is calculated from the determined OH number.

[0030] In a preferred alternative embodiment, the alternative polyethers are polyether polyols, wherein these alternative polyether polyols have an average hydroxyl functionality of 2 to 8 and a number-average molecular weight in the range 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 in the range of 200 g / mol to 400 g / mol, where the number-average molecular weight is calculated from the determined OH number. These alternative polyether polyols are also obtained by reacting alkylene oxides and H-functional starter compounds in the presence of acidic, basic, and / or organometallic catalysts. These organometallic catalysts are, for example, double metal cyanide (DMC) catalysts.

[0031] Suitable alternative polyether polyols include poly(oxypropylene) polyols, poly(oxypropyleneoxyethylene) polyols, polytetramethylene ether glycols, and block copolymers containing poly(oxy)ethylene, poly(oxy)propylene, and / or poly(oxy)butylene blocks, such as poly(oxy)ethylene-poly(oxy)propylene block copolymers with terminal poly(oxy)ethylene blocks. Furthermore, tripropylene glycol, triethylene glycol, tetrapropylene glycol, tetraethylene glycol, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, as well as monoalkyl and dialkyl ethers of glycols and poly(alkylene glycol)s are also suitable.

[0032] In a particularly preferred alternative embodiment, the alternative polyether polyol is a polypropylene glycol and / or a polyethylene glycol with a number-average molecular weight in the range of 150 g / mol to less than 500 g / mol, wherein the number-average molecular weight is calculated from the determined OH number.

[0033] In a preferred embodiment of the method according to the invention, the stoichiometric ratio of compound (1) to compound (2) is from 50 to 1 to 1 to 50, preferably 20 to 1 to 1 to 20.

[0034] In an alternative embodiment of the method according to the invention, the complex-forming component contains no additional compound (2) besides the compound (1). Cyanide-free metal salt

[0035] Cyanide-free metal salts suitable for the preparation of the double metal cyanide compounds preferably have the general formula (IX), M(X) n (IX) where M is selected from the metal cations Zn 2+< , Fe 2+< , Ni 2+< , Mn 2+< , Co 2+< , Sr 2+< , Sn 2+< , Pb 2+< and Cu 2+< , preferably M is Zn 2+< , Fe 2+< , Co 2+< or Ni 2+< , X are one or more (i.e. different) anions, preferably an anion selected from the group of halides (i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate; n is 1 if X = sulfate, carbonate or oxalate and n is 2 if X = halide, hydroxide, cyanate, thiocyanate, isocyanate, isothiocyanate or nitrate, or suitable cyanide-free metal salts have the general formula (X), M r (X) 3 (X) where M is selected from the metal cations Fe 3+< , Al 3+< and Cr 3+< , X are one or more (i.e. different) anions, preferably an anion selected from the group of halides (i.e.Fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate; r is 2 if X = sulfate, carbonate or oxalate and r is 1 if X = halide, hydroxide, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate or nitrate, or suitable cyanide-free metal salts have the general formula (XI), M(X) s (XI) where M is selected from the metal cations Mo 4+< , V 4+< and W 4+< X are one or more (i.e. different) anions, preferably an anion selected from the group of halides (i.e.Fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate; s is 2 if X = sulfate, carbonate or oxalate and s is 4 if X = halide, hydroxide, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate or nitrate, or suitable cyanide-free metal salts have the general formula (XII), M(X)t (XII) where M is selected from the metal cations Mo 6+< and W 6+< X are one or more (i.e. different) anions, preferably an anion selected from the group of halides (i.e. fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate and nitrate; t is 3 if X = sulfate, carbonate or oxalate and t is 6 if X = halide, hydroxide, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate or nitrate.

[0036] In a preferred embodiment of the process according to the invention, the cyanide-free metal salt of the aqueous solution of a cyanide-free metal salt is one or more compounds and is selected from the group consisting of zinc chloride, zinc bromide, zinc iodide, zinc acetate, zinc acetylacetonate, zinc benzoate, zinc nitrate, iron(II) sulfate, iron(II) bromide, iron(II) chloride, cobalt(II) chloride, cobalt(II) thiocyanate, nickel(II) chloride and nickel(II) nitrate, with zinc chloride being particularly preferred. metal cyanide salt

[0037] Metal cyanide salts suitable for the preparation of the double metal cyanide compounds preferably have the general formula (XIII) (Y) a M'(CN) b (A) c (XIII) wherein M' is selected from one or more metal cations of the group consisting of Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ir(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V); preferably, M' is one or more metal cations of the group consisting of Co(II), Co(III), Fe(II), Fe(III), Cr(III), Ir(III) and Ni(II); Y is selected from one or more metal cations of the group consisting of alkali metal (i.e., Li< , Na< , K< , Rb< , Cs< ) and alkaline earth metal (i.e., Be 2< , Ca 2< , Mg 2< , Sr 2< , Ba 2< ); A is selected from one or more anions of the group consisting of halides (i.e.,Fluoride, chloride, bromide, iodide), hydroxide, sulfate, carbonate, cyanate, thiocyanate, isocyanate, isothiocyanate, carboxylate, oxalate or nitrate, and a, b and c are integers, wherein the values ​​for a, b and c are chosen such that the electroneutrality of the metal cyanide salt is given; a is preferably 1, 2, 3 or 4; b is preferably 4, 5 or 6; c preferably has the value 0.

[0038] In a preferred embodiment of the process according to the invention, the metal cyanide salt of the aqueous solution of a metal cyanide salt is one or more compounds and is selected from the group consisting of potassium hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobaltate(III) and lithium hexacyanocobaltate(III), particularly preferably potassium hexacyanocobaltate(III).

[0039] Preferred double metal cyanide compounds contained in the DMC catalysts according to the invention are compounds of the general formula (XIV) MX [M' X ,(CN) y ] z (XIV), wherein M is defined as in formula (IX) to (XII) and M' as in formula (XIII), and x, x', y and z are integers and chosen such that the electron neutrality of the double metal cyanide compound is given.

[0040] Preferably, x = 3, x' = 1, y = 6 and z = 2, M is Zn(II), Fe(II), Co(II) or Ni(II) and M' is Co(III), Fe(III), Cr(III) or Ir(III).

[0041] In a preferred embodiment of the process according to the invention, the double metal cyanide compound is one or more compounds selected from the group consisting of zinc hexacyanocobaltate(III), zinc hexacyanoiridate(III), zinc hexacyanoferrate(III), and cobalt(II) hexacyanocobaltate(III). Zinc hexacyanocobaltate(III) is particularly preferred. Organic complex ligand

[0042] The organic complex ligands added in the production of the DMC catalysts are disclosed, for example, in US 5,158,922 (see especially column 6, lines 9 to 65), US 3,404,109, US 3,829,505, US 3,941,849, EP-A 700,949, EP-A 761,708, JP 4,145,123, US 5,470,813, EP-A 743,093, WO 99 / 46042, and WO-A 97 / 40086. For example, water-soluble organic compounds with heteroatoms, such as oxygen, nitrogen, phosphorus, or sulfur, which can form complexes with the double metal cyanide compound, are used as organic complex ligands. Preferred organic complex ligands are alcohols, aldehydes, ketones, ethers, esters, amides, ureas, nitriles, sulfides, and mixtures thereof. Particularly preferred organic complex ligands are aliphatic ethers (such as dimethoxyethane), water-soluble aliphatic alcohols (such as ethanol, isopropanol, n-butanol, isobutanol, sec.-Butanol, tert-butanol, 2-methyl-3-buten-2-ol, and 2-methyl-3-butyn-2-ol), compounds containing both aliphatic or cycloaliphatic ether groups and aliphatic hydroxyl groups (such as ethylene glycol mono-tert-butyl ether, diethylene glycol mono-tert-butyl ether, tripropylene glycol mono-methyl ether, and 3-methyl-3-oxetan-methanol). Highly preferred organic complex ligands are selected from one or more compounds of 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-oxetan-methanol.

[0043] In a preferred embodiment of the process according to the invention, the organic complex ligand is one or more compounds and is 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-oxetan-methanol, particularly preferably tert-butanol. Mixing nozzle

[0044] The DMC catalyst dispersion is preferably produced using a mixing nozzle (e.g. a smooth jet nozzle, Levos nozzle, Bosch nozzle and similar), particularly preferably a jet disperser, as described in patent application WO 01 / 39883 A1.

[0045] The basic structure and operation of suitable mixing nozzles will be described below. Fig. 1Figure 1 shows the schematic setup of a simple smooth jet nozzle. The reactant stream 1 is first accelerated in nozzle 3 and atomized at high velocity into the slower-flowing reactant stream 2. This accelerates reactant stream 2 and decelerates reactant stream 1. During this process, some of the kinetic energy of reactant stream 1 is converted into heat and is therefore no longer available for the mixing process. The two reactant streams are then mixed via the turbulent decay of the resulting jet into vortices of different sizes (vortex cascade). Compared to a stirred tank reactor, concentration differences can be reduced significantly faster in this way, as considerably higher and more homogeneous power densities can be achieved. The average power density P is calculated using the following formula: P = Δ p ⋅ V ˙ V with: Δp: Pressure drop in the nozzle V: Volume flow rate V: Volume of the nozzle orifice

[0046] The use of such nozzles will be referred to below as Method 1.

[0047] In a smooth jet nozzle, a first reactant stream is accelerated in a nozzle and atomized at high velocity into a slower-flowing second reactant stream. The mixing of the two reactant streams then occurs via the turbulent breakup of the resulting jet into vortices of different sizes (vortex cascade). Compared to a stirred tank reactor, concentration differences can be reduced significantly faster in this way, as considerably higher and more homogeneous power densities can be achieved. Beam disperser

[0048] A jet disperser such as that described in [reference to relevant document] is particularly preferred for the process according to the invention. Fig. 2 or Fig. 3 The beam disperser can be constructed as follows ( Fig. 2) that two nozzles 5 and 6 are arranged one behind the other. The reactant stream 1 is initially accelerated strongly in nozzle 5 due to the cross-sectional constriction. The accelerated jet, due to its high flow velocity, draws in the second component. The distance between the nozzles is preferably selected such that, due to the short residence time in the mixing chamber 4, only nucleation occurs, but no crystal growth. The nucleation rate of the solid is therefore crucial for the optimal design of the jet disperser. Advantageously, a residence time of 0.0001 s to 0.15 s, preferably 0.001 s to 0.1 s, is set. Crystal growth only occurs in the outlet 3. The diameter of the nozzles 6 should preferably be selected such that further acceleration of the partially mixed reactant streams occurs there.Due to the additional shear forces occurring in the nozzles 6, the state of homogeneous mixing is achieved in a shorter time through faster vortex disintegration compared to Method 1. Therefore, unlike Method 1, it is possible to achieve a state of ideal mixing of the reactants even in precipitation reactions with very high nucleation rates, thus enabling the establishment of defined stoichiometric compositions during the precipitation reaction. Nozzle diameters of 5000 µm to 50 µm, preferably 2000 µm to 200 µm, have proven advantageous for nozzle pressure losses of 0.1 bar to 1000 bar or power densities in the range of 1 × 10⁷ W / m³ to 1 × 10¹³ W / m³. This mixing process will be referred to as Method 2 in the following.

[0049] Depending on the desired particle size, n additional nozzles (with n = 1 - 5) can be added downstream, resulting in a multi-stage jet disperser. Fig. 3 A multi-stage jet disperser of this type is shown. Following nozzle 6, the dispersion is passed through nozzle 7 again. The same principles apply to the design of the nozzle diameters as for nozzle 6.

[0050] The additional advantage of further dispersers compared to Method 2 is that the high shear forces in the nozzles allow for the mechanical comminution of particles already formed. In this way, it is possible to produce particles with diameters ranging from 10 µm to 0.1 µm. Instead of several nozzles connected in series, comminution can also be achieved by recirculating the dispersion. The use of such nozzles is referred to below as Method 3.

[0051] Energy dissipation in the nozzles and the enthalpy of crystallization can lead to heating of the dispersion. Since temperature can have a significant influence on the crystallization process, a heat exchanger can be installed downstream of the mixing element to ensure isothermal operation.

[0052] A trouble-free scale-up is possible, for example, by using a larger number of bores, connecting several mixing elements in parallel, or increasing the free nozzle area. However, the latter is not achieved by increasing the nozzle diameter, as this can lead to core flow, resulting in a deterioration of the mixing result. Therefore, for nozzles with large free nozzle areas, slots with a correspondingly large area should preferably be used.

[0053] The DMC catalyst dispersion is preferably produced using a mixing nozzle, and particularly preferably a jet disperser. Examples of suitable apparatus are given in Figs. 4 and 5 shown. Fig. 4 demonstrates a semi-batch process using a loop reactor, Fig. 5 a continuous process for the production of the DMC catalyst dispersion.

[0054] In one embodiment of the process according to the invention, the production of the double metal cyanide catalyst (DMC) comprises (i) in a first step, the reaction of the aqueous solution of the cyanide-free metal salt, the aqueous solution of the metal cyanide salt, the organic complex ligand, and the complex-forming component, which contains one or more compounds (1) of formula (I) (according to claim 1), to form a dispersion; (ii) optionally in a second step, the separation of the solid from the dispersion obtained from (i); (iii) optionally in a third step, the washing of the isolated solid with an aqueous solution of an organic complex ligand by means of a filter cake washing; (iv) and optionally in a fourth step, the drying of the solid obtained. Step i)

[0055] Preferably, aqueous solutions of the cyanide-free metal salt, e.g., zinc chloride, used in stoichiometric excess (at least 50 mol% based on the metal cyanide salt), and of the metal cyanide salt, e.g., potassium hexacyanocobaltate, are first reacted in the presence of the organic complex ligand, which can be, for example, tert-butanol, forming a dispersion. This DMC catalyst dispersion is preferably prepared using a mixing nozzle, particularly preferably a jet disperser.

[0056] The production of the DMC catalyst dispersion in a semi-batch process using a jet disperser in combination with a loop reactor (according to Fig. 4The following section explains the process. Either the aqueous solution of a cyanide-free metal salt from container B2 can be circulated and the aqueous metal cyanide solution from container B1 added, or vice versa. When both streams are combined in the mixing device M, a dispersion of the DMC compound is formed. The DMC compound dispersion can be prepared according to method 1, 2, or 3, preferably according to method 2 or 3. The advantage of these methods is the ability to maintain a constant reactant ratio throughout the entire precipitation process.

[0057] Preferably, the dispersion formed is circulated through the jet disperser for several minutes to several hours after precipitation.

[0058] The nozzle diameters are preferably between 2000 µm and 200 µm, with pressure losses in the nozzle between 0.1 bar and 1000 bar.

[0059] The organic complex ligand can be present in the aqueous solution of the cyanide-free metal salt and / or the metal cyanide salt, or it can be added directly to the dispersion obtained after precipitation of the double metal cyanide compound (via container B1 or B2).

[0060] In one embodiment of the method according to the invention, a complex-forming component containing one or more compounds (1) of formula (I) is subsequently added to the dispersion circulating in the circuit through the jet disperser via container B1 or B2. The complex-forming component containing one or more compounds (1) of formula (I) is preferably used in a mixture of water and organic complex ligand.

[0061] The dosing of the complexing component, which contains one or more compound(s) (1) of formula (I), into the circuit and subsequent recirculation preferably takes place under pressure losses in the nozzle between 0.001 bar and 10 bar.

[0062] According to the invention, the DMC catalyst dispersion can also be carried out in a continuous process, as exemplified in Fig. 5 The aqueous solutions of the cyanide-free metal salt and the metal cyanide salt are reacted in the mixing organ M1 according to method 1, 2, or 3, forming a dispersion. The organic complex ligand may be present in the aqueous solution of the cyanide-free metal salt and / or the metal cyanide salt. In this case, the step in Fig. 5The mixing stage M2. It is also possible to add the organic complex ligand after the precipitation of the double metal cyanide compound via mixing organ M2. To increase the residence time of the dispersion, it can be recirculated via mixing organ M2. Subsequently, the complex-forming component, which contains one or more compounds (1) of formula (I) – preferably in a mixture of water and organic complex ligand – can be added in mixing organ M3 and recirculated to increase the residence time. Process temperature

[0063] In a preferred embodiment of the method according to the invention, a process temperature between 26°C and 49°C, preferably between 28°C and 47°C, particularly preferably between 29°C and 42°C, and most preferably between 30°C and 40°C is used in step i). Here, the process temperature corresponds to the process temperature in vessel B2. Fig. 4A process temperature between 26°C and 49°C, preferably between 28°C and 47°C, particularly preferably between 29°C and 42°C and most preferably between 30°C and 40°C leads to a further improvement in the activity of the DMC catalyst. Step (ii)

[0064] In a preferred embodiment of the method according to the invention, in a second step (ii) the solid is separated from the dispersion obtained from (i).

[0065] In this process, the solid (i.e., the precursor of the catalyst according to the invention) is isolated from the dispersion by known techniques, such as centrifugation or filtration.

[0066] Suitable filter devices are described, for example, in "Ullmann's Encyclopedia of Industrial Chemistry", Vol. B 2, Chapters 9 and 10, VCH, Weinheim, 1988 and H. Gasper, D. Oechsle, E. Pongratz (eds.): "Handbook of Industrial Solid / Liquid Filtration", Wiley-VCH Verlag GmbH, Weinheim, 2000.

[0067] The pressure gradient required for filtration can be applied by gravity, by centrifugal force (e.g. filter centrifuges), preferably by gas differential pressure (e.g. vacuum filters or pressure filters) or by liquid pressure (e.g. filter presses, drum or disc filters and possibly cross-flow filtration modules).

[0068] Both batch and continuous filter devices can be used to separate the catalysts. Examples of batch filter devices include peeling and inverting filter centrifuges, membrane, chamber, frame or tube filter presses, press filters, auto-press devices, disc pressure, candle and plate filters, as well as vacuum and pressure filters. Examples of continuous filter devices include belt filters, pressure and vacuum drum filters, pressure and vacuum disc filters, belt filters and cross-flow filters.

[0069] Vacuum or pressure filters or filter presses are particularly suitable for filtering the DMC catalyst dispersion on a laboratory scale; pressure filter presses, filter presses and press filter machines are suitable on a pilot plant and production scale.

[0070] Membrane filter presses have proven particularly suitable in pilot and technical plant scales. These enable the filtration of the DMC catalyst dispersion by means of an applied liquid pressure gradient, using a suitable filter cloth, preferably a membrane cloth.

[0071] Filtration is carried out at temperatures of 10 to 80°C. The applied pressure differentials can be 0.001 bar to 200 bar, preferably 0.1 bar to 100 bar, and particularly preferably 0.1 bar to 25 bar, the applied pressure differential depending on the device used. Step (iii)

[0072] The isolated solid obtained in step (ii) can be washed by redispersion or filter cake washing.

[0073] In a preferred embodiment of the method according to the invention, in a third step (iii) the isolated solid is washed with an aqueous solution of an organic complex ligand by means of a filter cake washing.

[0074] Filter cake washing is preferably carried out by mashing or, more preferably, by flow-through washing. In this process, the cake is permeated with the washing liquid, and the liquid previously contained within the cake is displaced, with diffusion effects also taking effect. Dehumidification of the washed cake can be achieved by differential gas pressure, centrifugal force, or mechanical pressing, or preferably by a combination of differential gas pressure dehumidification followed by mechanical pressing. The pressure for mechanical pressing can be applied either mechanically or by membranes.

[0075] Filter cake washing simplifies and thus accelerates the manufacturing process. The preferred ratio of washing liquid to filter cake volume is that which ensures a complete exchange of the liquid present in the original filter cake.

[0076] In an alternative preferred embodiment of the process according to the invention, the isolated solid is subsequently washed in a third process step with an aqueous solution of the organic complex ligand (e.g., by redispersion and subsequent re-isolation by filtration or centrifugation). In this way, for example, water-soluble byproducts such as potassium chloride can be removed from the catalyst according to the invention. Preferably, the amount of the organic complex ligand in the aqueous washing solution is between 40 and 80 wt%, based on the total solution.

[0077] Optionally, in the third step, a complexing component containing one or more compounds (1) of formula (I) is added to the aqueous washing solution, preferably in the range between 0.5 and 5 wt.%, based on the total solution.

[0078] Furthermore, it is advantageous to wash the isolated solid more than once. Preferably, in a first washing step (iii-1), an aqueous solution of the organic complex ligand is used (e.g., by redispersion and subsequent re-isolation by filtration or centrifugation) to remove, for example, water-soluble byproducts such as potassium chloride from the catalyst according to the invention. The amount of the organic complex ligand in the aqueous washing solution is particularly preferably between 40 and 80 wt.%, based on the total solution of the first washing step. In the further washing steps (iii-2), either the first washing step is repeated once or several times, preferably one to three times, or preferably a non-aqueous solution, such as potassium chloride, is used.a mixture or solution of organic complex ligand and complex-forming component containing one or more compound(s) (1) of formula (I), (preferably in the range between 0.5 and 5 wt.%, based on the total amount of the washing solution of step (iii-2)), used as a washing solution and the solid is washed with it once or several times, preferably once to three times. Step (iv)

[0079] In a preferred embodiment of the process according to the invention, the obtained solid is subsequently dried in a fourth step (iv).

[0080] In this process, the isolated and, if necessary, washed solid is then, if necessary after pulverization, subjected to temperatures generally ranging from 20 to 100°C and pressures generally ranging from 0.1 mbar to Normal pressure (1013 mbar) dried. Steps (ii) and (iii)

[0081] In a preferred embodiment of the method according to the invention, steps (ii) and (iii) are carried out in a filter press.

[0082] It has proven advantageous to press the washed filter cake at pressures of 0.5 to 200 bar, preferably at the highest possible pressures, after washing. This can be done, for example, directly after washing in a filter press or using other suitable pressing devices that allow the application of mechanical pressure, so that the liquid present in the filter cake can escape through a membrane or a suitable filter cloth. The subsequent mechanical dehumidification of the filter cake, preferably before drying, can preferably be carried out in the filter press, ideally by mechanically pressing it out under pressure applied to the membranes. Mechanical dehumidification preferably leads to the most complete possible removal of the washing liquid from the filter cake. Steps (ii), (iii) and (iv)

[0083] The DMC catalyst is then dried at temperatures of approximately 20 to 100°C and at pressures of approximately 0.1 mbar to atmospheric pressure (1013 mbar). Contact dryers, convection dryers, and spray dryers are suitable for this purpose. Drying is also preferably carried out directly in the mechanical liquid separation devices if these are suitable (e.g., Nutsch dryers, centrifugal dryers, "hot filter press").

[0084] In a particularly preferred embodiment of the method according to the invention, steps (ii), (iii) and (iv) are carried out in a heated filter press.

[0085] The process preferably employs a heated filter press. This is constructed like a conventional filter press with a membrane pack. The membrane plates used differ from conventional membrane plates in that a heating medium can flow through the space behind the membrane. Liquid-tight (so-called "drip-tight" or "gas-tight") membrane filter plates are preferably used.

[0086] The heated heating medium flows along the back side of the press membranes, completely separated from the filter cake, through the press membrane and the filter medium, thus heating the filter cake. The press medium is under sufficiently high pressure to ensure contact between the membranes and the filter cake. The filter cakes can be heated on one or both sides. Heating on both sides is advantageous in terms of drying time.

[0087] To support the drying process, a vacuum is applied to the filtrate side. This vacuum can be generated, for example, by a liquid ring pump. The extracted vapor stream is cooled before the vacuum pump to condense the volatile components (e.g., tert-butanol and water). The measured and controlled variables are the amount of condensed material, the pressure in the press's filtrate system, and the filter cake temperature.

[0088] In the described process, the membrane pressures are preferably 0.1 bar to 10 bar. Temperatures of the pressing and heating medium are 30°C to 80°C, preferably 40°C to 60°C. The filtrate-side pressure is preferably less than 100 mbar. The flow rate of the heating medium should be selected to ensure good heat transfer between the heating medium and the product. Drying times typically range from a few minutes to several hours, usually one to ten hours. Residual moisture levels below the target value of approximately 5% are reliably achieved with this type of drying.

[0089] In further process steps, the product, thus isolated and freed from impurities, can be ground and packaged. Product-by-process claim

[0090] Another object of the present invention is the DMC catalyst produced according to the inventive method.

[0091] Another object of the present invention is the use of the DMC catalysts produced according to the inventive process in a process for the production of polyoxyalkylene polyols, preferably polyether polyols by polyaddition of alkylene oxides to starter compounds having active hydrogen atoms and / or polyether carbonate polyols by polyaddition of alkylene oxides to starter compounds having active hydrogen atoms in the presence of carbon dioxide.

[0092] The DMC catalysts produced according to the inventive process can, due to their exceptionally high activity, often be used in very low concentrations (25 ppm and less, based on the amount of polyoxyalkylene polyol, preferably polyether polyol, to be produced). If the polyoxyalkylene polyols, preferably polyether polyols, produced in the presence of the DMC catalysts produced according to the inventive process are used for the production of polyurethanes, removal of the catalyst from the polyoxyalkylene polyol, preferably polyether polyol, can be omitted without adversely affecting the product qualities of the polyurethane obtained. Examples

[0093] The OH numbers were determined according to DIN 53240. The viscosities were determined using a rotational viscometer (Physica MCR 51, manufacturer: Anton Paar) according to DIN 53018. Production of DMC catalysts: Example 1 (comparison):

[0094] The catalyst was tested using an apparatus according to Fig. 4 Made from WO 01 / 39883 A1.

[0095] In a loop reactor that incorporates a beam disperser according to Fig. 2 from WO 01 / 39883 A1 with a bore (diameter 0.7 mm), a solution of 258 g zinc chloride in 937 g distilled water and 135 g tert-butanol was circulated at 35°C (determined in container D2 in Fig. 4WO 01 / 39883 A1). For this purpose, a solution of 26 g potassium hexacyanocobaltate in 332 g distilled water was added. The pressure drop in the jet disperser was 2.9 bar. The resulting dispersion was then circulated for 60 min at 35°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 added, and the dispersion was then circulated for 80 min at 35°C and a pressure drop of 2.9 bar in the jet disperser.

[0096] 230 g of the resulting dispersion were filtered in a pressure filter basket with a filter area of ​​20 cm² and subsequently washed with a mixture of 82 g tert-butanol, 42.3 g distilled water, and 1.7 g polypropylene glycol 1000. The washed filter cake was mechanically pressed between two strips of filter paper and finally dried for 2 hours at 60°C under high vacuum at approximately 0.05 bar (absolute). Example 2:

[0097] Example 2 was carried out analogously to Example 1 (comparison), with the difference that in the corresponding manufacturing steps, tri-sec.-butylphenol ethoxylate with 13 EO (Clariant ®< Sapogenat T 130) was used instead of polypropylene glycol 1000 (PPG-1000) in identical amounts of 27.6 g and 1.7 g, respectively. Example 3:

[0098] Example 3 was carried out analogously to Example 1 (comparison), with the difference that in the corresponding manufacturing steps, tri-sec.-butylphenol ethoxylate with 18 EO (Clariant ®< Sapogenat T 180) was used instead of polypropylene glycol 1000 (PPG-1000) in identical amounts of 27.6 g and 1.7 g respectively. Example 4:

[0099] Example 4 was carried out analogously to Example 1 (comparison), with the difference that in the corresponding manufacturing steps, tri-sec.-butylphenol ethoxylate with 50 EO (Clariant ®< Sapogenat T 500) was used instead of polypropylene glycol 1000 (PPG-1000) in identical amounts of 27.6 g and 1.7 g, respectively. Catalyst testing (“8K Diol Stressed Test”):

[0100] The DMC catalysts were tested using the so-called "8K Diol Stressed Test." Starting with a bifunctional polypropylene glycol starter with an OH number of 147 mg KOH / g ("Arcol Polyol 725" from Covestro), a polypropylene glycol with a calculated OH number of 14 mg KOH / g, i.e., a molecular weight of 8,000 g / mol ("8K Diol"), was produced using a short propylene oxide dosing time (30 minutes). The decisive criterion for assessing catalyst quality / activity in this test is the viscosity of the resulting polyol, with a DMC catalyst of higher quality / activity leading to a lower 8K Diol viscosity. General procedure:

[0101] In a 1-liter stainless steel reactor, 75 g of a bifunctional polypropylene glycol starter (OH number = 147 mg KOH / g) and 30.7 mg of DMC catalyst were placed. After five nitrogen / vacuum exchanges between 0.1 and 3.0 bar (absolute), the reactor contents were heated to 130°C while stirring (800 rpm). The mixture was then stripped with nitrogen for 30 minutes at 130°C and 100 mbar (absolute). Subsequently, 7.5 g of propylene oxide were added at 130°C and 100 mbar (absolute) to activate the catalyst. Catalyst activation manifested itself as an accelerated pressure drop in the reactor. After successful catalyst activation, the remaining propylene oxide (685.7 g) was added over 30 minutes at 130°C with stirring (800 rpm). Following a post-reaction time of 30 minutes at 130°C, volatile components were distilled off under vacuum (< 10 mbar) at 90°C for 30 minutes. The product was then cooled to room temperature and removed from the reactor.The OH number and viscosity (25°C) of the obtained product were measured. In case of a deviation between the measured and the calculated OH number (14 mg KOH / g), a "corrected viscosity" was determined from the measured viscosity using the following formula: corrected viscosity (25°C) = measured viscosity (25°C) + 659 * (OH number - 14).

[0102] The results of the catalyst tests in the "8K Diol Stressed Test" are summarized in Table 1. Table 1: Catalyst testing / Example DMC catalyst / example OH number [mg KOH / g] Viscosity at 25°C / measured [mPas] Viscosity at 25°C / corrected [mPas] 5 (See below) 1 (See below) 14,0 4324 4324 6 2 14,1 3950 4016 7 3 14,2 3695 3827 8 4 13,9 3845 3779

[0103] The results show that DMC catalysts produced using tri-sec.-butylphenol ethoxylate as a complexing component lead to lower viscosity values ​​of the polyols in the "8K Diol Stressed Test", a semi-batch polyol production process, compared to DMC catalysts using polypropylene glycol 1000 as a complexing component. Catalyst testing (continuous process):

[0104] The following components were dosed at the specified mass flow rates into a continuously operated stainless steel pressure reactor with an accessible reactor volume VR of 1.951 liters, filled with a polyether polyol (OH functionality = 2.82; OH number = 48 mg KOH / g; propylene oxide / ethylene oxide ratio = 89.5 / 10.5; containing 25 ppm DMC catalyst) at a temperature of 130°C while stirring (800 rpm): Propylene oxide at 817.50 g / h, ethylene oxide at 95.51 g / h, glycerol at 21.69 g / h, dispersion of 0.00613 g DMC catalyst in 1 g propylene glycol at 3.83 g / h

[0105] The reaction mixture was continuously drawn from the pressure reactor, which was always completely filled with liquid so that the reaction volume V corresponded to the reactor volume VR. To complete the reaction, the drawn reaction mixture was continuously transferred to a post-reactor (a tubular reactor with an internal volume of 1.0 L) heated to 100°C. After exiting the post-reactor, the resulting product was cooled to room temperature and then analyzed. Table 2 shows the analytical values ​​of a sample taken after a total reaction time corresponding to 12 residence times.

[0106] The OH number and viscosity (at 25°C) were measured. In case of a deviation between the measured and calculated OH number (48 mg KOH / g), a "corrected viscosity" was determined from the measured viscosity using the following formula: corrected viscosity (25°C) = measured viscosity (25°C) + 13 * (OH number - 48) Table 2: Catalyst testing / Example DMC catalyst / example OH number [mg KOH / g] Viscosity at 25°C / measured [mPas] Viscosity 25°C / corrected [mPas] 9 (See below) 1 (See below) 47,4 731 723 10 3 47,6 708 703 11 4 47,6 703 698

[0107] The results show that DMC catalysts produced using tri-sec.-butylphenol ethoxylate as a complexing component also lead to lower viscosity values ​​of the polyols in the continuous polyol production process compared to DMC catalysts using polypropylene glycol 1000 as a complexing component.

Claims

1. Process for preparing a double metal cyanide catalyst (DMC) comprising i) reacting an aqueous solution of a cyanide-free metal salt, an aqueous solution of a metal cyanide salt, an organic complex ligand and a complex-forming component, characterized in that the complex-forming component contains one or more compounds (1) of formula (I):         R1-O-(R2-O)n-H     (I) where R1 is a substituted or unsubstituted aryl group, R2 is an alkylene group, preferably an ethylene group or isopropylene group, particularly preferably ethylene group (Et), and n ≥ 1, preferably 5 ≤ n ≤ 80, particularly preferably 7 ≤ n ≤ 70, very particularly preferably 8 ≤ n ≤ 60.

2. Process according to Claim 1, wherein R1 has a structure according to formula (II): where R3, R4, R5, R6, R7 are independently of one another selected from the group consisting of hydrogen, linear or branched alkyl groups having 1 to 22 carbon atoms, cycloaliphatic groups containing 3 to 22 carbon atoms and substituted or unsubstituted aryl groups having 6 to 16 carbon atoms, wherein preferably R3, R5, R7 are independently of one another selected from the group consisting of hydrogen, linear or branched alkyl groups having 1 to 22 carbon atoms, cycloaliphatic groups containing 3 to 22 carbon atoms and substituted or unsubstituted aryl groups having 6 to 16 carbon atoms and R4 and R6 are hydrogen.

3. Process according to Claim 1 or 2, wherein: R3, R5, R7 are independently of one another selected from the group consisting of linear or branched alkyl groups having 1 to 10 carbon atoms and substituted or unsubstituted aryl groups having 6 to 12 carbon atoms and R4 and R6 are hydrogen.

4. Process according to any of Claims 1 to 3, wherein R1 has a structure according to formula (III), (IV) or (V) :

5. Process according to any of Claims 1 to 4, wherein the compound (1) has a structure according to formula (VI), (VII) and / or (VIII): where n ≥ 1, preferably 5 ≤ n ≤ 80, particularly preferably 7 ≤ n ≤ 70, most preferably 8 ≤ n ≤ 60.

6. Process according to any of Claims 1 to 5, wherein double metal cyanide compounds of formula (XIV) are present in the DMC-catalyst         Mx [M'x, (CN)y]z     (XIV), and M is selected from one or more metal cations of the group consisting of Zn(II), Fe(II), Ni(II), Mn(II), Co(II), Sr(II), Sn(II), Pb(II) and Cu(II), preferably Zn(II), Fe(II), Co(II) and Ni(II), and M' is selected from one or more metal cations of the group consisting of Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ir(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V), preferably Co(III), Fe(III), Cr(III) and Ir(III), and x, x', y and z are integers and are selected so as to ensure the electronic neutrality of the double metal cyanide compound, wherein preferably x = 3, x' = 1, y = 6 and z = 2.

7. Process according to any of Claims 1 to 6, wherein the double metal cyanide compound is one or more compounds selected from the group consisting of zinc hexacyanocobaltate(III), zinc hexacyanoiridate(III), zinc hexacyanoferrate(III) and cobalt(II) hexacyanocobaltate(III), preferably zinc hexacyanocobaltate(III).

8. Process according to any of Claims 1 to 7, wherein the metal cyanide salt is one or more compounds selected from the group consisting of potassium hexacyanocobaltate(III), potassium hexacyanoferrate(II), potassium hexacyanoferrate(III), calcium hexacyanocobaltate(III) and lithium hexacyanocobaltate(III).

9. Process according to any of Claims 1 to 8, wherein the organic complex 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, preferably tert-butanol.

10. Process according to any of Claims 1 to 9, wherein the complex-forming component further contains a compound (2), wherein the compound (2) is a polyether, preferably a polyether polyol.

11. Process according to Claim 10, wherein the molar ratio of compound (1) to compound (2) is from 50:1 to 1:50, preferably 20:1 to 1:20.

12. Process according to any of Claims 1 to 11, wherein the reaction in step i) is carried out using a mixing nozzle, preferably a jet disperser.

13. Process according to any of Claims 1 to 12, wherein the employed process temperature of the dispersion during the reaction in step i) is between 26°C and 49°C, preferably between 28°C and 47°C, particularly preferably between 29°C and 42°C and very particularly preferably between 30°C and 40°C.

14. Double metal cyanide catalyst (DMC) obtainable in accordance with any of Claims 1 to 13.

15. Use of a double metal cyanide catalyst (DMC) according to Claim 14 for the preparation of polyoxyalkylene polyols, preferably polyether polyols and / or polyethercarbonate polyols.