CN118027383A - Fatty acid glyceride ethoxylation narrow-distribution catalyst and preparation method and application thereof - Google Patents

Abstract

The invention discloses a fatty acid glyceride ethoxylation narrow-distribution catalyst, a preparation method and application thereof, relates to the technical field of fatty acid glyceride ethoxylation catalyst preparation, and adopts a hydrothermal method to prepare the fatty acid glyceride ethoxylation narrow-distribution catalyst. Meanwhile, the product produced by the catalyst prepared by the invention has good color and luster, is milky white (colorless transparent liquid after melting), has narrow relative molecular weight distribution, and has low content of byproducts (polyethylene glycol and dioxane).

Description

A narrow distribution catalyst for fatty acid glyceride ethoxylation and its preparation method and application

Technical Field

The invention relates to the technical field of preparation of catalysts for ethoxylation of fatty acid glycerides, and in particular to a narrow distribution catalyst for ethoxylation of fatty acid glycerides and a preparation method and application thereof.

Background technique

Nonionic surfactants are surfactants that contain ether groups that do not dissociate in aqueous solution as the main hydrophilic group in the molecule, and their surface activity is reflected by neutral molecules. Nonionic surfactants have high surface activity, good solubilization, washing, antistatic, calcium soap dispersion and other properties, low irritation, and excellent wetting and washing functions. The applicable pH range is wider than that of general ionic surfactants, and can also be used with other ionic surfactants. Adding a small amount of nonionic surfactants to ionic surfactants can improve the surface activity of the system.

According to the structure of the hydrophilic group, nonionic surfactants can be divided into polyoxyethylene type, polyol type, alkanolamide type, polyether type, amine oxide type, etc. Among them, the production of polyoxyethylene type surfactants requires alcohols, phenols, carboxylic acids, amides and other compounds containing active hydrogen as raw materials, which are polymerized with epoxy compounds such as ethylene oxide or propylene oxide under acidic or alkaline catalyst conditions.

Polyoxyethylene ester products are non-toxic and non-irritating; they have good skin compatibility and can reduce the irritation of formulated products; especially the triglyceride structure, which has excellent emulsification properties for edible oils and mineral oils and excellent oil solubilization ability. Polyoxyethylene ester products include the following characteristics: ①. The product itself has a certain viscosity, so it has a significant thickening effect on the anionic system; ②. The product itself is a medium foaming product and has no obvious inhibitory effect on the foam of the formula system; ③. The product has a good fat-enriching effect and can be used to increase the conditioning of personal protection products; ④. The HLB value of the product can be adjusted at will, and it has excellent properties such as good low-temperature solubility, resistance to hard water, easy biodegradation, and good lubricity. It can be used in dishwashing detergents, oil phase regulators, food emulsifiers, leather fatliquors, metal cutting fluids and some chemical fiber oils. However, for ester-based reaction substrates, since they have no active hydrogen, ordinary acidic or alkaline catalysts have almost no catalytic activity. If you want to obtain polyoxyethylene ester surfactants, you need to proceed in two steps: 1. Ethoxylate the carboxylic acid or alcohol substrate, and 2. Esterify the product of the first step. This two-step synthesis process is cumbersome and has high production costs. It has been reported in the literature that ester compounds can be directly ethoxylated with ethylene oxide in one step using magnesium-aluminum composite metal oxide as a catalyst. However, its catalytic efficiency is low, the reaction conversion rate is low, and there are many by-products. The preparation of magnesium-aluminum composite metal oxide catalysts and ethoxylation with long-chain alkane monoesters as reaction substrates now have the following specific technical solutions:

Magnesium oxide is dispersed in pure water, and a certain amount of aluminum nitrate aqueous solution is added to allow aluminum ions to be impregnated on the surface of the magnesium oxide. The obtained powder is filtered, rinsed, dried and then calcined to obtain a magnesium-aluminum composite metal oxide catalyst (aluminum content is 0.8-3.0%, calcination temperature is 400-950°C).

A certain amount of methyl laurate and catalyst were placed in an autoclave, and the air in the autoclave was replaced with nitrogen; then the mixture was heated, and a certain amount of ethylene oxide was introduced into the autoclave, and the temperature was maintained at 180°C and the pressure was 3atm. After aging and cooling, the reaction mixture was filtered to remove the catalyst to obtain EFME. The optimal reaction activity was 0.53g-EO·min ^-1 ·g-cat ^-1 .

Patent document CN102558411B discloses "a preparation process of an ether-ester copolymer water-reducing agent". The ethoxy catalyst used in the preparation process includes: 30-90wt% of alkaline earth metal oxide, 1-40wt% of group III metal ions, and 1-30wt% of a carrier.

Patent document CN1730145A discloses "an ethoxylate of fat and its preparation method", comprising: adding 2.6g of catalyst to 90g of soybean oil, putting it into a 1L high-pressure reactor while stirring, starting stirring, replacing air with nitrogen, heating to 180°C, introducing ethylene oxide, maintaining the system pressure at 0.4MPa, closing the EO feed valve when the amount of ethylene oxide added is 238g, aging for 10min, cooling to 70°C, discharging the material, weighing 329.5g, and obtaining a product with a single-chain average ethylene oxide content of 18.0 - soybean oil ethoxylate.

At present, most of the nonionic surfactants on the market are compounds containing active hydrogen, such as alcohols and carboxylic acids, which are ethoxylated under the action of catalysts to obtain fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, etc. However, there are few reports on ethoxylation catalysts for fatty acid monoglycerides, fatty acid diglycerides, and fatty acid triglycerides without active hydrogen compounds, and the reported catalysts have low catalytic activity, most of which are less than 1.0g-EO·min ^-1 ·g-cat ^-1 . At the same time, the polyoxyethylene fatty acid glycerides prepared using the catalysts have a wide relative molecular weight distribution and yellow color.

Summary of the invention

The object of the present invention is to provide a narrow distribution catalyst for the ethoxylation of fatty acid glycerides and a preparation method and application thereof. The catalyst for the ethoxylation of fatty acid glycerides of the present invention has the advantages of high catalytic activity, high raw material (ethylene oxide) conversion rate, and long service life, and the catalyst can restore the catalytic activity through simple activation and regeneration, and can be industrially produced and put into use. At the same time, the product produced using the catalyst prepared by the present invention has good color, is milky white (a colorless and transparent liquid after melting), has a narrow relative molecular weight distribution, and has a low content of by-products (polyethylene glycol and dioxane). To achieve the above purpose, the present invention provides the following technical scheme:

The first object of the present invention is to provide a method for preparing a narrow distribution catalyst for ethoxylation of fatty acid glycerides, the method comprising the following steps:

Step S1, accurately weighing magnesium salt, aluminum salt, urea and organic acid, adding solvent, stirring and dissolving, transferring into a polytetrafluoroethylene hydrothermal kettle, heating to 150-180° C., keeping warm for 2-48 hours, and cooling naturally; obtaining a yellow turbid liquid, filtering, washing the filter cake with distilled water for 3 times until the filtrate is neutral; drying the filter cake, grinding to obtain a catalyst precursor (Mg-Al-CA-LDH);

Step S2, raising the temperature of the precursor to 300-800° C. at a program rate of 1-20° C./min, keeping the temperature for 0.5-10 h, and cooling naturally to obtain a catalyst.

Furthermore, in step S1, the molar ratio of magnesium salt to aluminum salt is 1:1 to 9:1; the alkaline compounds generated after heating include urea and ammonium bicarbonate, and the molar ratio of their usage to magnesium salt is 2:1 to 10:1; the molar ratio of magnesium salt to organic acid is 1:1 to 8:1.

Further, the magnesium salt is one of magnesium nitrate hexahydrate, magnesium sulfate heptahydrate or magnesium chloride hexahydrate;

The aluminum salt is one of aluminum nitrate nonahydrate, aluminum chloride hexahydrate or aluminum sulfate 18hydrate.

Furthermore, in step S1, the solvent includes one or more of ethylene glycol, water, ethanol, isopropanol, glycerol, DMF or MDSO.

Furthermore, in step S1, the organic acid includes one of citric acid, acetic acid, malic acid, sorbic acid, benzoic acid, salicylic acid, tartaric acid, lactic acid, lauric acid or arachidic acid.

Furthermore, in step S2, the initial temperature of the programmed temperature increase is 25°C, the heating rate is 1-20°C/min, the end temperature is 300-800°C, and the holding time is 0.5-10h.

The second object of the present invention is to provide a narrow distribution catalyst for ethoxylation of fatty acid glycerides, which is prepared by the method described above.

The third object of the present invention is to provide an application of the above-mentioned narrow distribution catalyst for ethoxylation of fatty acid glycerides, wherein the catalyst is used for ethoxylation reaction of fatty acid ester substrates; wherein the fatty acid esters include: natural animal and plant oils and C _8-20 triglycerides; vegetable oils include rapeseed oil, cottonseed oil, coconut oil, palm oil, olive oil, palm kernel oil, litsea cubeba oil, rice bran oil or fragrant fruit oil; animal oils include butter, sheep fat or lard.

Technical effects and advantages of the present invention:

(1) Natural animal and plant oils and fats often do not contain active hydrogen and are difficult to ethoxylate. The use of traditional acidic catalysts (such as sulfuric acid, phosphoric acid, aluminum chloride, etc.) or alkaline catalysts (such as sodium hydroxide, potassium hydroxide, etc.) does not have a good catalytic effect. The magnesium-aluminum composite metal oxide prepared by the present invention is a solid acid-base bifunctional catalyst, which has both alkaline active sites generated by magnesium oxide and acidic active sites generated by aluminum oxide, and the solid catalyst is easy to separate from the product.

(2) The magnesium-aluminum composite metal oxide catalysts prepared by the prior art are mostly prepared by the impregnation method, in which aluminum ions are impregnated into the surface of magnesium oxide or a carrier. Due to the limitation of the preparation method, this method cannot prepare a magnesium-aluminum composite metal catalyst with a high aluminum content. However, the higher the aluminum ion content, the more acidic active sites are provided, and the higher the catalytic activity. The present invention adopts a hydrothermal method, by adding a base or a compound that can generate alkalinity after heating, so that the magnesium, aluminum and other ions in the solution are completely precipitated. This method can prepare a composite metal oxide catalyst with a high aluminum content, and the aluminum content of the catalyst can be arbitrarily controlled.

(3) The catalyst of the present invention has simple preparation process, cheap and easy-to-obtain raw materials, high catalytic activity, few by-products, high selectivity, long service life, easy regeneration and other properties, and is more suitable for industrial production. The present invention uses magnesium aluminum hydrotalcite containing organic acid, and the magnesium aluminum composite metal oxide obtained after calcination has higher catalytic activity, the raw material (ethylene oxide) conversion rate is as high as 98% or more, the product color is light, the relative molecular weight distribution is narrow, and the by-product polyethylene glycol and dioxane content are less than 0.1% and 10ppm, respectively. The prior art scheme does not mention the ethylene oxide conversion rate and by-product content.

(4) The catalytic activity of the catalyst prepared by the present invention reaches 3.0g-EO·min ^-1 ·g-cat ^-1 , which is much higher than that of the prior art. In addition, after 50 hours of continuous production, the catalytic activity of the catalyst prepared by the present invention is 90% of that of the fresh catalyst; after 100 hours of continuous production, the catalytic activity is 85% of that of the fresh catalyst. The catalytic activity of the used catalyst can be restored to more than 97% of that of the fresh catalyst through simple activation and regeneration. The catalyst of the prior art only shows the stability of the catalyst after 12 repeated uses, and when the catalyst is not used, the catalytic activity drops to 80% after being stored for 1 year, and the catalytic activity drops to less than 40% after being stored for 1.5 years, and the catalytic activity cannot be restored by catalyst regeneration.

(5) The existing technical solutions are mainly for long-chain fatty acid monoester substrates, among which methyl laurate is the most common. The catalyst prepared by the present invention can be used for long-chain fatty acid triglyceride substrates, mainly castor oil, hydrogenated castor oil and other animal and plant oils. Compared with monoester substrates, triglyceride substrates have greater steric hindrance and greater reaction difficulty.

Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a diagram showing the properties of a catalyst precursor prepared in Example 1 of the present invention;

FIG2 is a diagram showing the properties of the catalyst prepared in Example 1 of the present invention;

FIG. 3 is a graph showing the properties of polyoxyethylene hydrogenated castor oil, a product of Test Example 1 of the present invention.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The first object of the present invention is to provide a method for preparing a narrow distribution catalyst for ethoxylation of fatty acid glycerides by a hydrothermal method, the method comprising the following steps:

Step S1, weigh magnesium salt, aluminum salt, urea, and organic acid in a beaker, add solvent, stir and dissolve, transfer to a 100mL polytetrafluoroethylene hydrothermal kettle, heat to 150-180°C, keep warm for 2-48 hours, and cool naturally; obtain a yellow turbid liquid, filter, and wash the filter cake with distilled water 3 times until the filtrate is neutral. Dry the filter cake and grind to obtain a catalyst precursor.

Step S2, the precursor is heated to 300-800°C at a program rate of 1-20°C/min, the initial temperature of the program temperature is 25°C, the heating rate is 1-20°C/min, the temperature is kept for 0.5-10h, and the temperature is naturally lowered to obtain a catalyst. Wherein, the molar ratio of magnesium salt to aluminum salt is 1:1-9:1; the molar ratio of urea usage to magnesium salt is 2:1-10:1; the molar ratio of magnesium salt to organic acid is 1:1-8:1; wherein the solvent includes but is not limited to one or more of ethylene glycol, water, ethanol, isopropanol, glycerol, DMF or MDSO; the organic acid includes but is not limited to one or more of citric acid, acetic acid, malic acid, sorbic acid, benzoic acid, salicylic acid, tartaric acid, lactic acid, lauric acid or arachidic acid.

The second object of the present invention is to provide a narrow distribution catalyst for the ethoxylation of fatty acid glycerides, wherein a magnesium-aluminum composite metal oxide is obtained by calcining hydrotalcite as a catalyst; a hydrotalcite containing an organic acid is synthesized by a hydrothermal method, and the interlayer structure of the magnesium-aluminum hydrotalcite is changed by using small molecules of the organic acid to achieve the purpose of modifying the hydrotalcite, and the magnesium-aluminum composite metal oxide is obtained after calcining as a catalyst.

The third purpose of the present invention is to provide an application of a narrow distribution catalyst for ethoxylation of fatty acid glycerides. The magnesium-aluminum composite metal oxide prepared by the present invention is used as a catalyst for ethoxylation of fatty acid ester substrates; wherein the fatty acid esters include: natural animal and plant oils and fats and C _8-20 triglycerides, the plant oils include rapeseed oil, cottonseed oil, coconut oil, palm oil, olive oil, palm kernel oil, litsea cubeba oil, rice bran oil or fragrant fruit oil, etc.; the animal oils include: butter, sheep oil or lard, etc.

The pharmaceutical reagents used in the present invention include: magnesium nitrate hexahydrate (Mg(NO ₂ ) ₂ ·6H ₂ O), aluminum nitrate nonahydrate (Al(NO ₂ ) ₃ ·9H ₂ O), sodium hydroxide (NaOH), anhydrous sodium carbonate (Na ₂ CO ₃ ), urea (CH ₄ N ₂ O), citric acid (C ₆ H ₈ O ₇ ), ethylene glycol, ethanol, isopropanol, distilled water (self-made), hydrogenated castor oil, all of which are collected from Sinopharm Group and have analytical purity; hydrogenated castor oil (98%), produced by McLean; methyl laurate (analytical purity); lauric acid (analytical purity); ethylene oxide (EO) (provided by Wuhan Totem Industry and Trade Development Co., Ltd.).

Embodiment 1:

Preparation method of catalyst 1: accurately weigh Mg(NO ₃ ) ₂ ·6H ₂ O, Al(NO ₃ ) ₃ ·9H ₂ O, urea and citric acid into a beaker; add ethanol and water, stir and dissolve, then transfer to a 100mL polytetrafluoroethylene hydrothermal kettle, heat to 160°C for 135min, keep warm for 2880min, and cool naturally; obtain a yellow turbid liquid, filter, and wash the filter cake with distilled water 3 times until the filtrate is neutral. The filter cake is dried at 90°C for 12h, and ground to obtain a catalyst 1 precursor (magnesium aluminum hydrotalcite containing citric acid), the precursor is heated to 500°C at a rate of 5°C/min, kept warm for 60min, and cooled naturally to obtain catalyst 1. FIG1 is a display diagram of the properties of the catalyst precursor prepared in Example 1 of the present invention. As shown in FIG1 , the catalyst 1 precursor is a white powder; FIG2 is a display diagram of the properties of the catalyst prepared in Example 1 of the present invention. As shown in FIG2 , the catalyst 1 is a light yellow powder with a particle size of about 200 meshes.

Embodiment 2:

Preparation method of catalyst 2: accurately weigh Mg(NO ₃ ) ₂ ·6H ₂ O, Al(NO ₃ ) ₃ ·9H ₂ O, urea, and lauric acid into a beaker; add ethanol and water, stir and dissolve, then transfer to a 100 mL polytetrafluoroethylene hydrothermal kettle, heat to 160°C for 135 min, keep warm for 2880 min, and cool naturally; obtain a yellow turbid liquid, filter, and wash the filter cake with distilled water 3 times until the filtrate is neutral. Dry the filter cake at 90°C for 12 h, grind to obtain a catalyst 2 precursor (magnesium aluminum hydrotalcite containing lauric acid), heat the precursor to 500°C at a rate of 5°C/min, keep warm for 60 min, and cool naturally to obtain catalyst 2.

Test Example 1:

Activity test of catalyst 1: 70g hydrogenated castor oil and 2.8g catalyst 2 were added to a 500mL autoclave, heated to 90°C, and low-boiling substances and water in the system were removed by vacuum. Nitrogen was injected at 0.3MPa and vented to 0.01MPa for replacement three times, heated to 180°C, and 5g ethylene oxide was introduced to start the induction reaction. When the pressure dropped to 0.1MPa, ethylene oxide was continuously introduced (maintaining the pressure in the autoclave at 0.4MPa), and the ethylene oxide consumption was calculated by the electronic scale reduction method. When the amount of ethylene oxide added was 130g, the introduction was stopped. Aging to constant pressure, cooling to 90°C, and ethylene oxide gas in the reaction system was removed by vacuum. The product was weighed, and the apparent adduct number was calculated to be 40, and the catalytic activity of the catalyst was calculated to be 3.00g-EO·min ^-1 ·g-cat ^-1 . FIG3 is a property display diagram of the product of Test Example 1 of the present invention - polyoxyethylene hydrogenated castor oil. As shown in FIG3 , the product polyoxyethylene (40) hydrogenated castor oil is a white paste with a light color and no impurities remaining.

Test Example 2:

Activity test of catalyst 2: 70g hydrogenated castor oil and 2.8g catalyst 3 were added to a 500mL autoclave, heated to 90°C, and low-boiling substances and water in the system were removed by vacuum. Nitrogen was injected at 0.3MPa and vented to 0.01MPa for replacement three times, heated to 180°C, and 5g ethylene oxide was introduced to start the induction reaction. When the pressure dropped to 0.1MPa, ethylene oxide was continuously introduced (maintaining the pressure in the autoclave at 0.4MPa), and the ethylene oxide consumption was calculated by the electronic scale reduction method. When the amount of ethylene oxide added was 130g, the introduction was stopped. Aging to constant pressure, cooling to 90°C, and ethylene oxide gas in the reaction system was removed by vacuum. The product was weighed, and the apparent addition number was calculated to be 40, and the catalytic activity of the catalyst was calculated to be 3.45g-EO·min ^-1 ·g-cat ^-1 .

In summary, the fatty acid glyceride ethoxylation catalyst of the present invention has high catalytic activity (greater than 3.0

g-EO·min ^-1 ·g-cat ^-1 ), the raw material (ethylene oxide) conversion rate reaches 98%, the service life is up to 100h, and the catalyst can restore the catalytic activity through simple activation and regeneration. It can be industrialized and put into use. The product produced by the catalyst prepared by the present invention has good color, is milky white (colorless and transparent liquid after melting), has a narrow relative molecular weight distribution, and the content of by-product polyethylene glycol and dioxane is less than 0.1% and 10ppm.

Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A method for preparing a narrow distribution catalyst for ethoxylation of fatty acid glycerides, the method comprising the steps of:

s1, accurately weighing magnesium salt, aluminum salt, urea and organic acid, adding a solvent, stirring and dissolving, transferring into a polytetrafluoroethylene hydrothermal kettle, heating to 150-180 ℃, preserving heat for 2-48 h, and naturally cooling; obtaining yellow turbid liquid, filtering, washing a filter cake with distilled water for 3 times until the filtrate is neutral; drying and grinding a filter cake to obtain a catalyst precursor Mg-Al-CA-LDH;

and S2, heating the precursor to 300-800 ℃ at a programmed heating rate of 1-20 ℃/min, preserving heat for 0.5-10 h, and naturally cooling to obtain the catalyst.

2. The method for preparing the narrow-distribution catalyst for ethoxylation of fatty acid glycerides according to claim 1, wherein in step S1, the molar ratio of magnesium salt to aluminum salt is 1:1 to 9:1, a step of; the alkaline compound generated after heating comprises urea and ammonium bicarbonate, and the molar ratio of the usage amount to magnesium salt is 2:1 to 10:1, a step of; the molar ratio of magnesium salt to organic acid is 1:1 to 8:1.

3. The method for preparing a fatty acid glyceride ethoxylated narrow-distribution catalyst according to claim 2, wherein the magnesium salt is one of magnesium nitrate hexahydrate, magnesium sulfate heptahydrate or magnesium chloride hexahydrate;

The aluminum salt is one of aluminum nitrate nonahydrate, aluminum chloride hexahydrate or aluminum sulfate octadecahydrate.

4. The method for preparing a narrow distribution catalyst for ethoxylation of fatty acid glycerides according to claim 1, wherein in step S1, the solvent comprises one or more of ethylene glycol, water, ethanol, isopropanol, glycerol, DMF, or MDSO.

5. The method for preparing a fatty acid glyceride ethoxylated narrow-distribution catalyst according to claim 1, wherein in step S1, the organic acid includes one of citric acid, acetic acid, malic acid, sorbic acid, benzoic acid, salicylic acid, tartaric acid, lactic acid, lauric acid, and arachidic acid.

6. The method for preparing the fatty acid glyceride ethoxylation narrow-distribution catalyst according to claim 1, wherein in the step S2, the initial temperature of programmed heating is 25 ℃, the heating rate is 1-20 ℃/min, the termination temperature is 300-800 ℃, and the heat preservation time is 0.5-10 h.

7. A narrow distribution catalyst for ethoxylation of fatty acid glycerides, prepared by a process according to any one of claims 1 to 6.

8. Use of a fatty acid glyceride ethoxylation narrow-distribution catalyst according to claim 7, wherein the catalyst is for the ethoxylation of fatty acid ester substrates; wherein the fatty acid esters include: natural animal and vegetable oils and fats and C _8-20 triglycerides; vegetable oils include rapeseed oil, cottonseed oil, coconut oil, palm oil, olive oil, palm kernel oil, litsea cubeba oil, rice bran oil or bergamot oil; the animal oil comprises adeps bovis seu Bubali, adeps caprae seu ovis or adeps Sus Domestica.