Polyethers are prepared in large commercial quantities through the polymerization of alkylene oxides such as propylene oxide and ethylene oxide. The polymerization is usually conducted in the presence of an initiator compound and a catalyst. The initiator compound usually determines the functionality (number of hydroxyl groups per molecule) of the polymer and in some instances imparts some desired functional group. The catalyst is used to provide an economical rate of polymerization.

Metal cyanide complexes are becoming increasingly important alkylene oxide polymerization catalysts. These complexes are often referred to as"double metal cyanide"or"DMC"catalysts, and are the subject of a number of patents.

Those patents include, for example, U. S. Patent Nos. 3,278,457,3,278,458, 3,278,459,3,404,109,3,427,256,3,427,334,3,427,335 and 5,470,813, among many others. In some instances, these metal cyanide complexes provide the benefit of fast polymerization rates and narrow polydispersities. Additionally, these catalysts are associated with the production of polyethers having very low levels of monofunctional unsaturated compounds.

The most common of these metal cyanide complexes, zinc hexacyanocobaltate (together with the proper complexing agent and an amount of a poly (propylene oxide), has the advantages of being active and of forming poly (propylene oxide) having very low unsaturation. However, the catalyst is quite difficult to remove from the product polyether. Because of this difficulty, and because the catalyst can be used in small amounts, the usual practice is to simply leave the catalyst in the product. However, this means that the catalyst must be replaced. In addition, the presence of the residual catalyst in the polyether product has been reported to cause certain performance problems such as poor storage stability. In order to reduce catalyst expense and to avoid these problems, it would be desirable to provide a catalyst that can be recovered easily from the product polyether.

SUMMARY OF THE INVENTION

This invention is a process for preparing a supported metal cyanide catalyst, comprising (a) forming a slurry of the metal cyanide catalyst complex and an inorganic support that has ionic groups that are capable of exchanging cations in an organic sulfone (R5-S (0) 2-R5) or sulfoxide (R5-S (O)-R5) compound, (b) mixing the slurry under conditions sufficient to bind the metal cyanide catalyst to one or more ionic groups on the inorganic support, and (c) recovering the resulting supported metal cyanide catalyst from the slurry.

Active, supported metal cyanide polymerization catalysts are easily prepared in this manner.

DETAILED DESCRIPTION OF THE INVENTION By"metal cyanide catalyst", it is meant a catalyst represented by the formula Mb [Ml (CN) r (X) t] [M2 (X) 6] d'zL-aHsO'nMsy wherein M is a metal ion that forms an insoluble precipitate with the MI (CN) r (X) t group and which has at least one water soluble salt; MI and M2 are transition metal ions that may be the same or different; each X independently represents a group other than cyanide that coordinates with an MI or M2 ion; M3xAy represents a water-soluble salt of metal ion M3 and anion A, wherein M3 is the same as or different than M; L represents a complexing agent; b and c are positive numbers that, together with d, reflect an electrostatically neutral complex; d is zero or a positive number; x and y are numbers that reflect an electrostatically neutral salt; r is from 4 to 6; t is from 0 to 2; and z, a and n are positive numbers (which may be fractions) indicating the relative quantities of complexing agent, water and M3xAy, respectively.

The X groups in any M2 (X) 6 do not have to be all the same. The molar ratio of c: d is advantageously from about 100: 0 to about 20: 80, more preferably from about 100: 0 to about 50 : 50, and even more preferably from about 100: 0 to about 80: 20.

Similarly, mixtures of two or more different MI (CN) r (X) t groups can be used.

M and M3 are preferably metal ions selected from the group consisting of Zon+2 Fe+2, Co+2 Ni+2, MO+4, Mo+6, AI+3, V+4, V+5, Sr+2, W+4, W+e, Mn+2, Sn+2, Sn+4, Pb+2, Cu+2, La+3 and Cr+3. M and M3 are more preferably Zn+2, Fe+2, Co+2, Ni+2, La+3 and Cr+3. M is most preferably Zn+2.

MI and M2 are preferably Fe+3, Fe+2, Co+3, Co+2, Cr+2, Cr+3, Mn+2, Mn+3, Ir+3, Ni+2, Rh+3, Ru+2, V+4 and V+5. Among the foregoing, those in the plus-three oxidation state are more preferred. Co+3 and Fe+3 are even more preferred and Co+3 is most preferred. MI and M2 may be the same or different.

Preferred groups X include anions such as halide (especially chloride), hydroxide, sulfate, carbonate, oxalate, thiocyanate, isocyanate, isothiocyanate, Cl. 4 carboxylate and nitrite (NO2-), and uncharged species such as CO, H20 and NO.

Particularly preferred groups X are NO, N02-and CO. r is preferably 5 or 6, most preferably 6 and t is preferably 0 or 1, most preferably 0. In most instances, r + t will equal 6.

Suitable anions A include halides such as chloride and bromide, nitrate, sulfate, carbonate, cyanide, oxalate, thiocyanate, isocyanate, isothiocyanate, perchlorate and Cl. carboxylate. Chloride ion is especially preferred.

L represents an organic complexing agent. A great number of complexing agents are potentially useful, although catalyst activity may vary according to the selection of a particular complexing agent. Examples of such complexing agents include alcohols, aldehydes, ketones, ethers, amides, nitriles, sulfides, and the like.

Suitable alcohols include monoalcohols and polyalcohols. Suitable monoalcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, octanol, octadecanol, 3-butyn-1-ol, 3-butene-1-ol, propargyl alcohol, 2-methyl-2-propanol, 2-methyl-3-butyn-2-ol, 2-methyl-3-butene-2-ol, 3- butyn-1-ol, 3-butene-1-ol, 1-t-butoxy-2-propanol and the like. Suitable monoalcohols also include halogenated alcohols such as 2-chloroethanol, 2- bromoethanol, 2-chloro-1-propanol, 3-chloro-1-propanol, 3-bromo-1-propanol, 1, 3- dichloro-2-propanol, 1-chloro-2-methyl-2-propanol as well as nitroalcohols, keto- alcohols, ester-alcohols, cyanoalcohols, and other inertly substituted alcohols.

Suitable polyalcohols include ethylene glycol, propylene glycol, glycerine, 1,1,1-trimethylol propane, 1,1,1-trimethylol ethane, 1,2,3-trihydroxybutane, pentaerythritol, xylitol, arabitol, mannitol, 2,5-dimethyl-3-hexyn-2,5-diol, 2,4,7,9- tetramethyl-5-decyne-4,7-diol, sucrose, sorbitol, alkyl glucosides such as methyl

glucoside and ethyl glucoside, and the like. Low molecular weight polyether polyols, particular those having an equivalent weight of about 350 or less, more preferably about 125-250, are also useful complexing agents.

Suitable aldehydes include formaldehyde, acetaldehyde, butyraldehyde, valeric aldehyde, glyoxal, benzaldehyde, toluic aldehyde and the like. Suitable ketones include acetone, methyl ethyl ketone, 3-pentanone, 2-hexanone and the like.

Suitable ethers include cyclic ethers such as dioxane, trioxymethylene and paraformaldehyde as well as acyclic ethers such as diethyl ether, 1-ethoxy pentane, bis (betachloro ethyl) ether, methyl propyl ether, diethoxy methane, dialkyl ethers of alkylene or polyalkylene glycols (such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and octaethylene glycol dimethyl ether), and the like.

Amides such as formamide, acetamide, propionamide, butyramide and valeramide are useful complexing agents. Esters such as amyl formate, ethyl formate, hexyl formate, propyl formate, ethyl acetate, methyl acetate, triethylene glycol diacetate and the like can be used as well. Suitable nitriles include acetonitrile, proprionitrile and the like. Suitable sulfides include dimethyl sulfide, diethyl sulfide, dibutyl sulfide, diamyl sulfide and the like.

Preferred complexing agents are t-butanol, 1-t-butoxy-2-propanol, polyether polyols having an equivalent weight of about 75-350 and dialkyl ethers of alkylene and polyalkylene glycols. Especially preferred complexing agents are t-butanol, 1- t-butoxy-2-propanol, polyether polyols having an equivalent weight of 125-250 and a dimethyl ether of mono-, di-or triethylene glycol. t-Butanol and glyme (1,2- dimethoxy ethane) are most preferred.

The catalyst complex is conveniently made by first dissolving or dispersing a water-soluble metal cyanide compound in an inert solvent such as water or methanol. Mixtures of two or more metal cyanide compounds can be used. The water-soluble metal cyanide compound is represented by the general formula Bu [M' (CN) r (X) t] v, in which B is hydrogen or a metal that forms a water-soluble salt with the [Ml (CN) r (X) t] ion, u and v are integers that result in an electrostatically neutral compound and Ml, X, r and t are as described before. B is preferably hydrogen, sodium or potassium. Compounds in which B is hydrogen are conveniently formed by passing an aqueous solution of the corresponding alkali metal salt through a cation-exchange resin that is in the hydrogen form.

In addition, the solution or dispersion of the metal cyanide compound may also contain compounds that have the structure Bu [M2 (X) 6] v, wherein M2 is a transition metal and X, B, u and v are as before. M2 may be the same as or different from MI.

The solution or dispersion is then combined the resulting solution (s) with an aqueous solution of a water soluble metal salt, in the presence of the organic complexing agent. The metal salt is represented by the general formula MxAy, where M, A, x and y are as defined before. Especially suitable metal salts include zinc halides, zinc hydroxide, zinc sulfate, zinc carbonate, zinc cyanide, zinc oxalate, zinc thiocyanate, zinc isocyanate, zinc Ci-4 carboxylates, and zinc nitrate. Zinc chloride is most preferred.

The temperature of mixing is not critical, provided that the starting materials remain in solution or well dispersed until the mixing is performed.

Temperatures of about 10 to about the boiling point of the inert solvent, particularly 15-40°C, are most suitable. The mixing can be done with rapid agitation. Intimate mixing techniques as are described in U. S. Patent No.

5,470,813 can be used, but are not necessary.

In precipitating the catalyst, at least enough metal salt is used to provide one equivalent of metal ion (M) for each equivalent of metal cyanide ion (M1 (CN) r (X) t), plus each equivalent of M2 (X) 6 ion, if used. It has been found that in general, more active catalysts are those prepared using an excess of the metal salt.

This excess metal is believed to exist in the catalyst complex as a salt in the form MxAy or M3, Ay. This excess metal salt can be added in the precipitation step, such as by adding up to about three equivalents of metal salt, preferably from about 1.1 to about 3, more preferably about 1.5 to about 2.5 equivalents of metal salt, per combined equivalents of metal cyanide ion plus any M2 (X) 6 ions.

It is preferred to add the solution of the metal cyanide compound to that of the metal salt, and it is also preferred that the mixing be done with agitation.

Agitation is preferably continued for a period after the mixing is completed. The metal cyanide catalyst precipitates and forms a dispersion in the supernatant fluid.

The catalyst complex may be precipitated by mixing the solution or dispersion of the metal salt with the solution or dispersion of the metal cyanide compound in the presence of the organic complexing agent. One way of doing this is to add the complexing agent to the solution or dispersion of the metal cyanide

compound before the solutions are mixed. Alternately, both starting solutions or dispersions may be added simultaneously with the complexing agent. A third way is to mix the starting solutions or dispersions, followed immediately by adding the complexing agent. After adding this initial amount of complexing agent, the mixture is generally stirred for several minutes to allow the desired catalyst complex to form and precipitate.

The resulting precipitated catalyst complex is then recovered by a suitable technique such as filtration or centrifugation. Preferably, the catalyst complex is subjected to one or more subsequent washings with water, complexing agent, polyether polyol (when used) or some combination thereof. This is conveniently done by re-slurrying the catalyst in the liquid with agitation for several minutes and filtering. Washing is preferably continued at least until essentially all unwanted ions, particularly alkali metal and halide ions, are removed from the complex.

It has been found that catalyst preparation is sometimes easier if the catalyst is treated with a polyether polyol of a molecular weight of about 300-4000.

When a polyether polyol is used in the catalyst complex, it can be added with the initial amount of complexing agent, or in one or more subsequent washings of the complex.

The final catalyst complex is conveniently dried, preferably under vacuum and moderately elevated temperatures (such as from about 50-60°C) to remove excess water and volatile organics. Drying is preferably done until the catalyst complex reaches a constant weight.

The catalyst complex is supported by forming a slurry of the catalyst complex, the inorganic support, and an organic sulfone or sulfoxide compound.

Suitable sulfone compounds are represented by the general formula R5-S (0) 2-R5, where each R5 is unsubstituted or inertly substituted alkyl, cycloalkyl, aryl, or, together with the other R5, forms part of a ring structure that includes the sulfur atom of the sulfone (-S (O) 2-) group. Suitable sulfoxide compounds are represented by the general formula R5-S (O)-R5, where each R5 is as just described. In this context,"inertly substituted"means that the group contains no substituent which undesirably reacts with the metal cyanide compound, its precursor compounds (as described below) or an alkylene oxide, or which otherwise undesirably interferes with the polymerization of an alkylene oxide. Examples of such inert substituents include ether, alkoxy, hydroxyl, nitrile, aldehyde, ketone, amide, sulfide,

additional sulfone or sulfoxide groups, and the like. Each R5 is preferably unsubstituted and is also preferably either an alkyl group or, together with the other R5, forms part of a ring structure that includes the sulfone or sulfoxide group. Especially preferred R5 groups are 1-4 carbon atom alkyl groups or those that together form a 5-8 member ring with the sulfur atom of the sulfone or sulfoxide groups. More preferred compounds are water-soluble, including for example, dimethyl sulfoxide (DMSO), tetramethylene sulfoxide, dimethyl sulfone and sulfolane (tetramethylene sulfone) and 2,2-sulfonyl diethanol.

The inorganic support contains ionic groups that can exchange cations.

Among the suitable supports are various types of clays, including montmorillonite clay, bentonite clay, Swy-1 clay, K-10 clay, and the like. The clay is preferably one that remains a solid and does not react significantly under the conditions of an alkylene oxide polymerization or copolymerization reaction, as described more below. It is preferred to dry the clay before using it, in order to remove excess water and volatiles.

The slurry of catalyst complex, inorganic support and sulfone or sulfoxide compound is mixed under conditions sufficient to bind the metal cyanide catalyst complex to one or more ionic groups on the inorganic support. This is conveniently done by agitating the mixture at ambient (about 25°C) temperatures up to the boiling temperature of the sulfone or sulfoxide compound, for a period of time.

About 5 minutes to several hours is usually sufficient. Usually, an excess of sulfone or sulfoxide compound is used over that which can be absorbed by the catalyst complex and the inorganic support.

The resulting supported metal cyanide catalyst is then recovered from the slurry. This can be done by a variety of solid/liquid separation techniques such as filtering, centrifugation, and the like. Residual quantities of the sulfone or sulfoxide compound are preferably stripped by drying at ambient or somewhat elevated temperature (i. e. up to about 95°c, more preferably up to about 60°C) and optionally, reduced pressure. Drying is conveniently continued until the supported catalyst complex reaches a constant weight.

The supported catalyst complex of the invention is used to polymerize alkylene oxides to make polyethers. In general, the process includes mixing a catalytically effective amount of the supported catalyst complex with an alkylene oxide under polymerization conditions and allowing the polymerization to proceed until the supply of alkylene oxide is essentially exhausted. The concentration of

the catalyst is selected to polymerize the alkylene oxide at a desired rate or within a desired period of time. Generally, a suitable amount of catalyst is from about 5 to about 10,000 parts by weight metal cyanide catalyst complex per million parts combined weight of alkylene oxide, and initiator and comonomers, if present. More preferred catalyst levels are from about 10, especially from about 25, to about 1000, more preferably about 250 ppm, on the same basis.

To control molecular weight, impart a desired functionality (number of hydroxyl groups/molecule) or a desired functional group, an initiator compound as described before is preferably mixed with the catalyst complex at the beginning of the reaction. Suitable initiator compounds include monoalcohols such methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, octanol, octadecanol, 3-butyn-1-ol, 3-butene-1-ol, propargyl alcohol, 2-methyl-2-propanol, 2- methyl-3-butyn-2-ol, 2-methyl-3-butene-2-ol, 3-butyn-1-ol, 3-butene-1-ol and the like. The suitable monoalcohol initiator compounds include halogenated alcohols such as 2-chloroethanol, 2-bromoethanol, 2-chloro-1-propanol, 3-chloro-1-propanol, 3-bromo-1-propanol, 1, 3-dichloro-2-propanol, 1-chloro-2-methyl-2-propanol as well as nitroalcohols, keto-alcohols, ester-alcohols, cyanoalcohols, and other inertly substituted alcohols. Suitable polyalcohol initiators include ethylene glycol, propylene glycol, glycerine, 1,1,1-trimethylol propane, 1,1,1-trimethylol ethane, 1,2,3-trihydroxybutane, pentaerythritol, xylitol, arabitol, mannitol, 2,5-dimethyl-3- hexyn-2,5-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, sucrose, sorbitol, alkyl glucosides such a methyl glucoside and ethyl glucoside and the like. Low molecular weight polyether polyols, particularly those having an equivalent weight of about 350 or less, more preferably about 125-250, are also useful initiator compounds.

Among the alkylene oxides that can be polymerized with the catalyst complex of the invention are ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, tetramethylene oxide, and mixtures thereof. Various alkylene oxides can be polymerized sequentially to make block copolymers. More preferably, the alkylene oxide is propylene oxide or a mixture of propylene oxide and ethylene oxide and/or butylene oxide. Especially preferred are propylene oxide alone or a mixture of at least 50 weight % propylene oxide and up to about 50 weight % ethylene oxide.

In addition, monomers that will copolymerize with the alkylene oxide in the presence of the catalyst complex can be used to prepare modified polyether polyols.

Such comonomers include oxetanes as described in U. S. Patent Nos. 3,278,457 and 3,404,109, and anhydrides as described in U. S. Patent Nos. 5,145,883 and 3,538,043, which yield polyethers and polyester or polyetherester polyols, respectively.

The polymerization reaction typically proceeds well at temperatures from about 25 to about 150°C, preferably from about 80-130°C. A convenient polymerization technique involves mixing the catalyst complex and initiator, and pressuring the reactor with the alkylene oxide. After a short induction period, polymerization proceeds, as indicated by a loss of pressure in the reactor. Once the polymerization has begun, additional alkylene oxide is conveniently fed to the reactor on demand, until enough alkylene oxide has been added to produce a polymer of the desired equivalent weight.

Another convenient polymerization technique is a continuous method. In such continuous processes, the initiator is continuously fed into a continuous reactor such as a continuously stirred tank reactor (CSTR) or a tubular reactor, which contains the catalyst. A feed of alkylene oxide is introduced into the reactor and the product continuously removed. The catalyst can also be fed continuously to the reactor if desired.

The catalyst of this invention is especially useful in making propylene oxide homopolymers and random copolymers of propylene oxide and up to about 15 weight percent ethylene oxide (based on all monomers). The polymers of particular interest have a hydroxyl equivalent weight of from about 800, preferably from about 1000, to about 5000, preferably about 4000, more preferably to about 2500, and unsaturation of no more than 0.02 meq/g, preferably no more than about 0.01 meq/g.

The product polymer may have various uses, depending on its molecular weight, equivalent weight, functionality and the presence of any functional groups.

Polyether polyols so made are useful as raw materials for making polyurethanes.

Polyethers can also be used as surfactants, hydraulic fluids, as raw materials for making surfactants and as starting materials for making aminated polyethers, among other uses.

The following examples are provided to illustrate the invention, but are not intended to limit its scope. All parts and percentages are by weight unless otherwise indicated.

Example 1 A zinc hexacyanocobaltate catalyst complexed with t-butanol is dispersed in dimethylsulfoxide and Swy-1 clay in the sodium from, and refluxed overnight. The resulting mixture is then dried using a hot plate, and washed with n-hexane. The product is the catalyst complex supported on the clay.

The supported catalyst (0.2 grams) is combined with 0.5 grams of a 700 molecular weight poly (propylene oxide) triol, 5 mL of propylene oxide and 10 mL n- hexane. The mixture is heated at 110°C until the propylene oxide has polymerized. The product has an Mw of 9162 and a polydispersity of 1.735.

Example 2 A zinc hexacyanocobaltate catalyst complexed with t-butanol is dispersed in sulfolan and K-10 clay in the sodium from, and refluxed overnight. The resulting mixture is then dried using a hot plate, and washed with n-hexane. The product is the catalyst complex supported on the clay.

The supported catalyst (0.2 grams) is combined with 0.5 grams of a 700 molecular weight poly (propylene oxide) triol, 5 mL of propylene oxide and 10 mL n- hexane. The mixture is heated at 110°C until the propylene oxide has polymerized. The product has an Mw of 7002 and a polydispersity of 1.563.