Calcium catalyst concentrates for synthesis of narrow range ethoxylates

Abstract

Methods of preparing a catalyst composition for preparing an alkoxylation product include, mixing to form a slurry: a calcium carboxylate salt having a general structure of: RCOO-Ca-OOCR', where R and R' are, independently, saturated or unsaturated C4 to C22 fatty acids, the molar ratio of Ca to fatty acid ranging from 1:2 to 1:4; one or more inorganic acids; and one or more inert solvents.

Description

[0001] CALCIUM CATALYST CONCENTRATES FOR SYNTHESIS OF NARROW RANGE ETHOXYLATES

[0002] FIELD

[0003] Embodiments relate to modified calcium-containing catalysts and the use thereof in the preparation of alkoxylation products.

[0004] BACKGROUND

[0005] A variety of products such as surfactants, glycol ethers, and polyethers are commercially prepared by reactions of alkylene oxides with starter compounds having at least one active hydrogen, generally, in the presence of an alkaline or acidic catalyst. The types and properties of the alkoxylation products depend on the presence of appropriate concentration of alkylene oxides and starter compounds, and nature of the catalyst. Depending on the nature of the catalyst, condensation products can vary in the number of alkylene repeats, creating a mixture having a range of a molecular weights.

[0006] Alkoxylation products having a wide range of molecular weights can restrict the flexibility in downstream product formulation options. For example, alkoxylation products functioning as surfactants may have poor solubility if there are too few hydrophilic alkylene repeats, or be unable to efficiently reduce surface tension per unit mass with too many repeats. Moreover, for the preparation of concentrates for dilution at point of use, narrow molecular weight distributions are desirable as the resulting surfactants have higher cloud points and utilize lower volumes of prevent gel formation.

[0007] Summary

[0008] In an aspect, embodiments disclosed herein are directed to methods of preparing a catalyst composition that include mixing to form a slurry: a calcium carboxylate salt having a general structure of: RCOO-Ca-OOCR’, where R and R’ are, independently, saturated or unsaturated C4 to C22 fatty acids, the molar ratio of Ca to fatty acid ranging from 1 :2 to 1 :4; one or more inorganic acids; and one or more inert solvents.

[0009] In another aspect, embodiments disclosed herein are directed to methods of preparing an alkoxylated product that include adding a catalyst composition to one or more starter compounds, wherein the catalyst system is present a concentration providing 10 ppm to 10,000 ppm of Ca; and adding one or more alkylene oxides to the starter compounds to generate the alkoxylated product; wherein the catalyst composition includes: a calcium carboxylate salt having a general structure of: RCOO-Ca-OOCR’, where R and R’ are, independently, saturated or unsaturated C4 to C22 fatty acids, the molar ratio of Ca to fatty acid ranging from 1:2 to 1:8; one or more inorganic acids; and one or more inert solvents.

[0010] Detailed Description

[0011] Embodiments relate to calcium-containing catalyst compositions and the use thereof in the preparation of alkoxylation products. Catalyst compositions disclosed herein arc produced by mix of a calcium carboxylates, inorganic acid, and inert solvent. Catalyst compositions include a homogeneous catalyst paste having an equivalent calcium ion concentration of about 10,000 ppm to 100,000 ppm in some cases, or may be further processed to produce a solid calcium catalyst. Methods may include the use of catalyst compositions to generate narrow molecular weight distribution (i.e., low polydispersity) alcohol alkoxylates.

[0012] Previous alkoxylation methods methods have utilized mixtures of calcium salts stabilized by chelants, which often lead to the production of water that can affect reactivity and high molecular weight byproducts that skew the molecular weight distribution of the resulting product. Moreover, water, high boiling point chelants, and other stabilizing additives can be difficult to remove, requiring additional processing steps (e.g., distillation, heating, aging) or cost (e.g., for specialized additives).

[0013] Methods disclosed herein include the production of alcohol alkoxylates by polyaddition of alkylene oxides (alkoxylation) onto an initiator (i.e., an alcohol starter compound) in the presence of a catalyst composition.

[0014] Catalyst compositions disclosed herein may include a mixture of calcium carboxylate, inorganic acid, and inert solvent that produce products having relatively uniform alkoxylate unit number and type, narrow molecular weight distributions, and minimizes byproduct formation.

[0015] Catalyst compositions may include one or more calcium carboxylates prepared from fatty acids, which increase the solubility of calcium ions in solution, enabling the formation of activated catalytic species for the formation of alkoxylates and controlling the polydispersity of the resulting product. Calcium carboxylates may have a molar ratio of calcium to carboxylate (e.g., fatty acid) of 1:2 or more, such as in a range of 1:2 to 1:6, or 1:2 to 1:4.

[0016] Calcium carboxylates may have a general structure of: RCOO-Ca-OOCR’, where R and R’ are, independently, saturated or unsaturated C4 to C22 fatty acids. Suitable fatty acids for generating calcium carboxylates may include, for example, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. Unsaturated fatty acids include palmitoleic, oleic, linoleic, linolenic acids, and the like.

[0017] Catalysts may include one or more calcium carboxylates at a percent by weight (wt%) ranging from 35 wt% to 80 wt%, or 40 wt% to 80 wt%.

[0018] Catalyst compositions may include one or more inorganic acids that are added to activate the calcium carboxylate component. Inorganic acids may include, for example, sulfuric acid, phosphoric acid, nitric acid, and the like. Catalyst compositions may include a percent by mole (mol%) of inorganic acid with respect to the calcium carboxylate of 50 mol% or more, such as in a range of 50 mol% to 90 mol %, or 50 mol% to 80 mol%.

[0019] Catalysts may include one or more inorganic acids at a percent by weight (wt%) ranging from 35 wt% to 80 wt%, or 40 wt% to 80 wt%.

[0020] Catalyst compositions may include one or more inert solvents, where an inert solvent lacks functional groups (e.g., alcohols, amines, thiols, etc) capable of reacting in an alkoxylation reaction. Suitable inert solvents may include, for example, toluene, xylene, benzene, cyclohexane, hexane, dimethyl sulfoxide, ketone or ether solvents such as diglyme, triglyme, 1,4-dioxane, diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane. and the like, dimethylformamide, N-methylpyrrolidone, 1,2- dichloroethane, chloroform, carbon tetrachloride, and the like.

[0021] Catalysts may include an inert solvent at a percent by weight (wt%) ranging from 5 wt% to 80 wt%, or 5 wt% to 75 wt%.

[0022] The catalyst composition may be in the form of a slurry or solvent solution that is added to a reactor for alkoxylation reactions. In some cases, the catalyst composition may be treated with a volatile wash solvent to precipitate a solid catalyst composition that can be removed by filtration or other suitable means. Suitable wash solvents may include dimethyl ether, diethyl ether, dimethoxy ethane, diethoxymethane, dibutylether, isopropyl ether, and the like. In some cases, solid catalyst compositions may be dried to remove trace solvents and other volatiles.

[0023] Catalyst compositions may be used to alkoxylate compounds having active or labile hydrogen atoms, including alcohols, phenols, polyols, carboxylic acids, amides, amines, esters and glycerides. Alkoxylation methods include the preparation of alcohol alkoxylates by the polyaddition of alkylene oxides onto a hydroxy functional starter compound in the presence of a catalyst composition. In some cases, alcohol alkoxylates may be prepared from a starter compound and 1 to 50 equivalents of at least one alkylene oxide. Starter compounds may have a hydroxyl functionality of 1 to 8. In some cases, starter compounds may include C6 to C20 alcohols, including linear or branched alcohols, such as 2-ethyl hexanol, 2-propyl heptanol, 2,6,8-trimethyl-4 nonanol, and the like. Other starter compounds may include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, triethanolamine, diethanolamine, diisopropanolamine, bisphenol A, glycerol, diglycerol, triglycerol, trimcthylolpropanc, di(trimcthylolpropanc) pcntacrythritol, dipcntacrythritol, tripcntacrythritol, sugars and sugar alcohols such as sucrose and sorbitol, and the like.

[0024] In some cases, catalyst compositions may be used to alkoxylate esters, such as fatty acid methyl esters and the like. Esters that can be alkoxylated can include monoesters and polyesters, such as diesters, triesters, and the like. Suitable esters may include starter compounds such as Cl to C6 alkyl esters of acids such as acetic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, eicosanoic acid, tricosanoic acid, and the like; ethylene glycol diesters, such as ethylene glycol diacetate, ethylene glycol dibutyrate, ethylene glycol dihexanoate, ethylene glycol dioctanoate, ethylene glycol didecanoate, ethylene glycol distearate, and the like; and triglycerides such as tributyrin, trilaurin, tri s tcari n , and the like.

[0025] Catalyst compositions may be applied to alkoxylation processes performed in accordance with known methods, including batch, semi-batch, or continuous methods. Catalyst compositions may be applied as a slurry, solution, or solid. In some cases, catalyst compositions may be formulated as a concentrate that is diluted at the point of use. Catalyst compositions formulated as slurries may have a Ca concentration of 5,000 ppm or more, such as in a range of 5,000 ppm to 100,000 ppm, or 10,000 ppm to 100,000 ppm. Catalyst compositions may be applied to a reaction with a starter compound as a slurry or diluted prior to use, such as in a range of 10 ppm to 10,000 ppm. For example, a catalyst composition may be diluted into a starter, such as to provide catalyst loadings of 15 ppm to 2000 ppm Ca ion relative to starter), and alkoxylation is then performed at 120 to 160 °C.

[0026] In an example process, an alkoxylation reaction of the present invention can be conducted by charging a suitable reaction vessel equipped for stirring and / or recirculating with a starter compound, purging / sparging, and heating under inert atmosphere (e.g., nitrogen). A catalyst composition is then introduced and heated to reaction temperature, followed by the addition of the alkylene oxide(s) reactant. Alcohol alkoxylate products generated may have a narrow molecular weight distribution and reduced concentrations of relatively over-alkoxylated materials that can affect viscosity and raise pour points, particularly when compared to standard caustic catalyzed processes. Methods disclosed herein may also produce products having lower quantities of stalling material impurities that can impart odor and hazardous volatile organics.

[0027] While formulation components and properties have been disclosed individually, it is envisioned that component elements may be included, excluded, or combined in any manner or subcombination utilizing any of the above concentration ranges and nested subranges therein. Further, that the recited formulation properties may be similarly achieved through various combinations of the recited components within the recited ranges.

[0028] Examples

[0029] The following examples are provided to illustrate the embodiments of the invention, but are not intended to limit the scope thereof. Table 1 provides the materials used in the following examples.

[0030] Example 1 : Catalyst preparation

[0031] In this example, inventive catalysts were generally prepared by combining the Ca carboxylate and solvent and homogenizing at 2500 rpm for 30 seconds. An aliquot of sulfuric acid was then added to the resulting mixture and mixing continued at 2500 rpm for 30 seconds. Specific catalyst formulations are as follows.

[0032] Catalyst 1 was prepared by suspending calcium stearate (9.11 g, 15 mmol, 1 equiv) in diglyme (10 mL), mixing, and adding sulfuric acid (0.40 mL, 0.74 g, 7.5 mmol, 0.5 equiv). The resulting mixture was mixed again to provide a smooth colorless paste with a concentration of 33,000 ppm in Ca.

[0033] Catalyst 2 was formed by washing Catalyst 1 with diethyl ether followed by filtration.

[0034] Catalyst 3 was formed similarly to Catalyst 1, but with methyl ethyl ketone rather than diglyme.

[0035] Catalyst 4 was prepared by applying vacuum to catalyst 3 overnight at room temperature to remove the methyl ethyl ketone.

[0036] Catalyst 5 was prepared similar to Catalyst 2, except with methyl ethyl ketone as the initial catalyst diluent, rather than the diglyme. The UCC catalysts were prepared according to the procedure in U.S. Pat. No. 4,754,075 with either dodecanol or EXXAL 1315 LE as the starter compound. The Lion catalyst was prepared according to US10315189B2. The Hreczuh catalyst was prepared in accordance with Example III of W02002038269A1. Example 2: Ethoxylation catalysis

[0037] In this example, sample catalysts were used to generate alcohol alkoxylates using a semi-batch process. In general, 45 g of starter was used for each reaction, and 7 equivalents of ethylene oxide was added with respect to the starter. Catalyst concentrations in Table 1 below are provided in terms of mass of metal (e.g., Ca or K) versus starter.

[0038] For the semi-batch process, a 300 mL semi-batch pressure reactor configuration was used that included an impeller, thermocouple, cooling coils, baffles, inputs for nitrogen and monomer, and an aluminum heating block. The reactor was charged with 45 grams of starter and catalyst composition. The reactor was then scaled and leak tested. The reactor was then purged with nitrogen and heated with stirring. The reactor was then purged for 5 minutes to remove any solvent from the catalyst addition. Monomer was then fed to the reactor at a rate that maintained 30 psi of EO partial pressure. Upon completion of monomer feed, the reaction was allowed to digest at 140 °C for 2 hr and then cooled to 50 °C under nitrogen purge. After purging at 50 °C for 10 min, the product was collected. Product characterization included characterization by liquid chromatography coupled with mass spectroscopy (LC-MS). Alkoxylation rate was quantified in terms of turnover frequency (TOF), defined as the number of moles of EO converted per hour, per catalytic site (i.e., (mol EO) / (mol Catalyst x hours of reaction)). Polydispersity was calculated Q, the product of the alkoxylate (i.e., EO) adduct number for the most prevalent product and the square of the percentage of the mass distribution that product represents. Residual alcohol was determined by GC-FID method.

[0039] LC-MS analysis was conducted on a 1 mg / mL surfactant solution prepared in McOH. A microliter of the sample was injected onto an Agilent 6538 LC- quadrupole time-of-flight (qTOF) instrument. An Agilent Zorbax C18 column (2.1 microns, 3.0 x 50 mm) was used for separation, and held at a constant 45 °C during the LC gradient separation. Water was used as mobile phase A and ACN was used as mobile phase B. The column flow was 0.7 mL / min and the post-column addition of 50 mM ammonium formate at 0.1 mL / min was used to improve the ionization intensities of the MS signals. The samples were analyzed using electrospray ionization (ESI) under positive mode. The data was processed using Mass Hunter (version B7). The residue alcohol was measured by gas chromatography (GC) coupled with mass spectrometry, using dodecanol as external standard. Measurement parameters are listed in Tables 2 and 3. Measured properties for each product tested are shown in Table 4.

[0040] In terms of alkoxylation rate, inventive catalyst compositions (IE1-IE4) outperformed the baseline (CE1). Similarly, the inventive catalyst compositions were faster than the UCC catalysts (CE2, CE3) by 10-20%. Inventive catalyst compositions also outperformed the Lion catalyst (CE4) in terms of rate. The inventive catalyst compositions were generally active at lower temperature, with higher TOF than CE1, even at higher temperature. In terms of selectivity, catalysts IE1 to IE8 performed better than the CE1 baseline.

[0041] Examples IE9 and IE 10 are provided to demonstrate the alkoxylation of a fatty acid ester methyl stearate. It is also noted that IE9 and IE10 also exhibited relatively short induction times for catalyst action at 11 minutes and 55 minutes, respectively.

[0042] While the foregoing is directed to exemplary embodiments, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims1. A method of preparing a catalyst composition, comprising mixing to form a slurry: a calcium carboxylate salt having a general structure of: RCOO-Ca-OOCR’, where R and R’ are, independently, saturated or unsaturated C4 to C22 fatty acids, the molar ratio of Ca to fatty acid ranging from 1 :2 to 1 :4; one or more inorganic acids; and one or more inert solvents.

2. The method of claim wherein the percent by mole (mol%) of inorganic acid with respect to the calcium carboxylate is at least 50 mol%.

3. The method of claim 1, wherein the inorganic acid is sulfuric acid.

4. The method of claim 1, wherein the one or more inert solvents is diglyme or methyl ethyl ketone.

5. The method of claim 1, further comprises combining the slurry with a wash solvent, and isolating a solid catalyst composition.

6. The method of claim 5, wherein the wash solvent is selected from one or more of dimethyl ether, diethyl ether, dimethoxy ethane, diethoxymethane, dibutylether, or isopropyl ether.

7. A catalyst composition formed by the method of claim 1.

8. A method of preparing an alkoxylated product comprising: adding a catalyst composition to one or more starter compounds, wherein the catalyst composition is present a concentration providing 10 ppm to 10,000 ppm of Ca; and adding one or more alkylene oxides to the starter compounds to generate the alkoxylated product; wherein the catalyst composition comprises:a calcium carboxylate salt having a general structure of: RCOO-Ca-OOCR’, where R and R’ arc, independently, saturated or unsaturated C4 to C22 fatty acids, the molar ratio of Ca to fatty acid ranging from 1:2 to 1:8; one or more inorganic acids; and one or more inert solvents.

9. The method of claim 8, wherein the alkylene oxide is ethylene oxide.

10. The method of claim 8, wherein the inorganic acid is sulfuric acid, phosphoric acid, or nitric acid.

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