WO2010111849A1

WO2010111849A1 - Solid basic catalyst for synthesizing alkanolamide compounds and preparation method thereof

Info

Publication number: WO2010111849A1
Application number: PCT/CN2009/072508
Authority: WO
Inventors: 张法智; 李海艳; 卢伟; 徐赛龙; 雷晓东; 段雪
Original assignee: 北京化工大学
Priority date: 2009-04-02
Filing date: 2009-06-29
Publication date: 2010-10-07
Also published as: CN101507917B; CN101507917A

Abstract

A solid basic catalyst for synthesizing alkanolamide compounds has the following general formula [Mg_1-xAl_x(OH^-)₂]^x+(OH^-)_x·mH₂O, wherein 0.2≤x≤0.33 and 0.1<m<10. The catalyst is prepared by calcining Mg-Al hydrotalcite precursors, and rehydrating. The catalyst can be used for synthesizing alkanolamide compounds having good surface activity.

Description

Solid base catalyst for synthesizing sterol amide compounds and preparation method thereof

The invention belongs to the technical field of solid base catalysts, in particular to a solid base catalyst for catalytic synthesis of sterol amide compounds and a preparation method thereof. Background technique

Biodiesel, also known as fatty acid methyl ester, is a new type of biomass fuel. It is a high-quality petrochemical fuel substitute. Its superior performance, environmental friendliness and recyclability have been paid attention to. However, its high cost has hindered the industrialization of biomass fuels. Increasing profits by producing high value-added chemical products is a hot issue at present. The natural fatty acid is used as a raw material to prepare a fat or oil derivative, and further a sterol amide compound is synthesized. Not only can it be turned into waste, but the products obtained are excellent in performance, good in biodegradability, low in pollution, and safe in use.

Sterol amide is a new type of nonionic surfactant, which is a pale yellow solid, non-toxic and non-irritating. The amide bond is present in its molecule and does not dissociate in an aqueous solution, and its hydrophilic group is mainly composed of a certain amount of hydroxyl groups. It is this feature that determines the superior performance of nonionic surfactants in some respects over ionic surfactants. Because it is not in the ionic state in the solution, it is not easily affected by the presence of strong electrolytes, and is not easily affected by acid and alkali. Therefore, it has good stability, good compatibility with other types of active agents, and can be easily mixed and used, with different structures. The solubility of sterol amide in water and organic solvents is also different. Compared with other surfactants, it has no cloud point, so it has good thickening, foam stabilization, foaming, decontamination, Calcium soap dispersion, emulsification and other properties, widely used in detergents, foam stabilizers, thickeners, softeners, rust inhibitors, antistatic agents.

In the conventional process, a fatty acid methyl ester is reacted with monoethanolamine to produce a sterol amide compound. The catalysts commonly used in the reaction are mainly liquid base catalysts such as potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, sodium methoxide, sodium ethoxide and the like. Among them, potassium carbonate, sodium carbonate, potassium hydroxide, Catalysts such as sodium hydroxide have poor selectivity and are difficult to recycle, which can seriously corrode equipment and cause great pollution to the environment. While catalysts such as sodium methoxide and sodium ethoxide make products with high purity and few by-products, their cost is high. Because sodium in sodium methoxide, sodium ethoxide, etc. is very active, the stability of sodium methoxide, sodium ethoxide, etc. is not good, and transportation and storage are inconvenient. For example, sodium methoxide is sensitive to oxygen, flammable, soluble in methanol and ethanol. It decomposes into methanol and sodium hydroxide in water and decomposes in air above 126.6 °C. It is well known that solid base catalysts have the advantages of non-corrosive equipment, low environmental pollution, and easy recovery compared with liquid base catalysts.

Hydrotalcite-like is a kind of layered inorganic functional material, which has the advantages of adjustable chemical composition of the laminate, adjustable ion species and quantity of layers, and is widely used as catalyst, separating agent, ion exchange and adsorbent, etc. LDHs composed of Li and linear acid can be used as adsorbents for hydrophobic compounds (J. Phys. Chem., 1989, 93: 376-382); separation is determined by the selectivity of LDHs and the insertion ability of isomers. Construct (J. Am. Chem. Soc" 1984, 106: 5772-5779); adsorption of trichlorophenol, trinitrophenol, etc. from wastewater (Appl. Clay Sci., 1995, 10: 131-145). Especially the solid base catalyst prepared by using hydrotalcite as precursor has shown good catalytic performance in various catalytic reactions. Zoltan et al. use MgAl-LDHs with Mg/Al ratio of 3 as intramolecular cyclization reaction and molecule. A base catalyst for the inter-cyclization reaction (J. Mol. Catal. A: Chemical, 2000, 161: 149-155). Rousselot et al. used Mg-Ga-Al-LDHs as a basic catalyst for the Knoevenagel condensation reaction and found High reactivity (Int. J. Inorg. Mater., 1999, 1 : 165-174 Reichle The human aldehyde-ketone condensation reaction on MgAl(O) composite oxide was studied. It was pointed out that this kind of base catalyst has higher life, high stability, high selectivity and stronger than other heterogeneous catalysts for aldehyde-ketone condensation reaction. Advantages of regenerability (J. Catal, 1980, 63: 295-306). However, there is no relevant literature or application report on the application of hydrotalcite-like compounds as solid base catalysts to the synthesis of sterol amides. The object of the present invention is to provide a solid base catalyst for synthesizing sterol amide compounds, which has the advantages of high activity, wide application range, simple preparation, low cost and the like.

The solid base catalyst for catalyzing the synthesis of sterol amide compounds provided by the present invention has the following chemical formula:

[Mg _1-x Al _x (OH ) ₂ ] ^x+ (OH ) _x · m3⁄40

Where x is in the range of 0.2 x 0.33; m is the amount of crystal water and 0.1 < m < 10. Another object of the present invention is to provide a process for the preparation of the catalyst. The preparation method of the solid base catalyst provided by the invention comprises: firstly preparing magnesium having a particle size of nanometer or micrometer by a preparation method of a conventional hydrotalcite-like material (such as nucleation/crystallization separation method and/or urea method) The aluminum hydrotalcite precursor, and then the obtained precursor is calcined and rehydrated to obtain the solid base catalyst of the present invention, which can be used for catalytic synthesis of sterol amide compounds.

More specifically, the method for providing a magnesium-aluminum hydrotalcite solid base catalyst according to the present invention comprises the following specific steps: firstly preparing magnesium aluminum by a preparation method of a conventional hydrotalcite-like material, such as a nucleation/crystallization separation method or a urea method. The hydrotalcite-like precursor, the precursor prepared by the nucleation/crystallization separation method and/or the urea method is calcined and rehydrated to obtain the solid base catalyst of the present invention. The obtained product was characterized by XRD, and the solid base catalyst was used to catalyze the synthesis of a sterol amide compound, and the yield and selectivity of the reaction were analyzed by liquid chromatography.

More specifically, the method of the present invention comprises:

(1) A magnesium-aluminum hydrotalcite precursor is prepared, the magnesium-aluminum hydrotalcite precursor having the following chemical formula:

[Mg _1-X A1 _X (0H ) ₂ ] ^X+ (C0 ₃ ² ) _χ/2 · nH ₂ 0

Wherein, x ranges from 0.2 x 0.33; n is the amount of crystal water, and 0.1 < n < 10, and the method for preparing the magnesium-aluminum hydrotalcite precursor comprises nucleation/crystallization separation or urea method When the preparation is carried out using a nucleation/crystallization separation method, the nucleation/crystallization isolation method includes:

A. preparing a mixed salt solution of a divalent soluble magnesium salt and a trivalent soluble aluminum salt, wherein The metal magnesium has an ion concentration of 0.12-12 mol/L, and the molar ratio of the divalent metal magnesium ion (Mg ²⁺ ) to the trivalent metal aluminum ion (Al ³⁺ ) (magnesium to aluminum ratio) is 1.5-5. Preferably 2-4;

The divalent soluble magnesium salt may be a water-soluble salt formed of magnesium and an organic acid and/or an inorganic acid. For example, the organic acid may be a monocarboxylic acid having a carbon number of 1 to 10, a carbon atom. One or more of a dicarboxylic acid having 2 to 10, a tricarboxylic acid having 4 to 10 carbon atoms, and an amino acid having 1 to 10 carbon atoms, such as formic acid, acetic acid, oxalic acid, Citric acid, etc. The inorganic acid may be sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid or the like.

The trivalent soluble aluminum salt may be a water-soluble salt formed of aluminum and an organic acid and/or an inorganic acid. For example, the organic acid may be a monocarboxylic acid having a carbon number of 1 to 10, a carbon atom. One or more of a dicarboxylic acid having 2 to 10, a tricarboxylic acid having 4 to 10 carbon atoms, and an amino acid having 1 to 10 carbon atoms, such as formic acid, acetic acid, oxalic acid, Citric acid, etc. The inorganic acid may be sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid or the like.

Preferably, the divalent soluble magnesium salt may be one or more of magnesium nitrate, magnesium sulfate, magnesium acetate and magnesium chloride, more preferably magnesium nitrate; the trivalent soluble aluminum salt is aluminum nitrate, aluminum sulfate One of aluminum acetate and aluminum chloride, more preferably aluminum nitrate;

B. preparing a mixed alkaline solution of a base and a soluble inorganic salt such that the concentration of the base in the obtained mixed alkaline solution is 0.096-9.6 mol/L, and the base and the soluble inorganic salt (for example, potassium and/or Or a soluble inorganic salt of sodium) in a molar ratio of 2-5, for example, may be 2.3-4, preferably 2.4-3.2; the base is sodium hydroxide and/or potassium hydroxide, preferably sodium hydroxide;

The soluble inorganic salt is an alkali metal carbonate and/or an alkali metal hydrogencarbonate such as sodium carbonate, potassium carbonate, sodium hydrogencarbonate and/or potassium hydrogencarbonate, preferably sodium carbonate and/or potassium carbonate. More preferably sodium carbonate;

D. The mixed salt solution prepared in the step A and the mixed alkaline solution prepared in the step B are added dropwise to the colloid mill at 5-70 ° C, and mixed for several minutes (for example, may be 1-10 minutes) , preferably 1.5-5 minutes, more preferably 2-3 minutes), then transferred into a three-necked bottle, at 10 ° C -100 ° C The slurry of the magnesium-aluminum hydrotalcite precursor is obtained in an amount of from 4 to 100 hours;

E. Centrifugally wash the slurry of the magnesium-aluminum hydrotalcite precursor obtained in step D several times to pH 7-8, and then dry at 10-120 ° C for 24 h to obtain the magnesium-aluminum hydrotalcite. Precursor.

When the magnesium-aluminum hydrotalcite precursor is prepared using the urea process, the urea process comprises:

A. preparing a mixed salt solution of a divalent soluble magnesium salt and a trivalent soluble aluminum salt, wherein the divalent metal magnesium has an ion concentration of 0.12-12 mol/L, and the divalent metal magnesium ion (Mg ²⁺ ) and the third The molar ratio (magnesium to aluminum ratio) of the valence metal aluminum ion (Al ³⁺ ) is 1.5-5, preferably 2-4;

C. Prepare a 0.1-5 mol/L urea solution;

D. The mixed salt solution prepared in the step A is uniformly mixed with the urea solution prepared in the step C, and then transferred into a stainless steel reaction vessel with a polytetrafluoroethylene liner, and reacted at 10 ° C - 110 ° C. 100 hours, obtaining a slurry of the magnesium-aluminum hydrotalcite precursor; and

E. Centrifugal washing of the slurry of the magnesium-aluminum hydrotalcite precursor obtained in the above step D The magnesium-calcium hydrotalcite precursor is obtained after the pH is 7-8, and then dried at 10-120 ° C for 24 h; (2) Preparation of magnesium-aluminum composite metal oxide

The magnesium-aluminum hydrotalcite precursor prepared by the above step (1) (that is, the hydrotalcite precursor prepared by the nucleation/crystallization separation method and/or the urea method) is placed in a nitrogen-protected atmosphere furnace at a constant temperature from room temperature. The heating rate is raised to the calcination temperature and then calcined. The calcination time is 1 to 50 hours, preferably 5 to 40 hours, more preferably 12 to 20 hours. After the calcination is completed, it is naturally cooled to room temperature, and the obtained product is obtained. a magnesium-aluminum composite metal oxide;

The room temperature means 10-40 ° C, preferably 15-20 ° C; the heating rate may be l-50 ° C / min, preferably 10-40 ° C / min; the calcination temperature may be 100- 1000 ° C, preferably 300-800 ° C; (3) Preparation of magnesium-aluminum hydrotalcite solid base catalyst

The magnesium-aluminum composite metal oxide obtained in the step (2) is placed in water in which C0 ₂ is removed, and rehydrated under nitrogen protection, wherein each gram of the magnesium-aluminum composite metal oxide is required for rehydration 20-200 ml of water from which CO ₂ is removed, preferably 40-150 ml, more preferably 80-120 ml, and the rehydration time is 1-50 hours, preferably 4-20 hours, more preferably 5-12 hours, then, the product is subjected to rapid suction filtration, and then dried in a vacuum drying oven at 10-80 ° C for 5 to 48 hours, preferably 10 to 35 hours, more preferably 20 to 30 hours. The product is the magnesium aluminum hydrotalcite solid base catalyst of the present invention. In an embodiment, the rehydration process may be accompanied by stirring, and the stirring speed may be 100-800 r/min, for example, 200-500 r/min, preferably 300-400 r/mino.

The solid base catalyst of the present invention can catalyze the amidation reaction of an ester with an ethanolamine, and the reaction formula of the chemical reaction is:

RCOORj + H ₂ NC ₂ H ₄ OH→ RCONHC ₂ H ₄ OH + HORi,

Wherein R is a linear or branched fluorenyl group having 12 to 18 carbon atoms and is a linear or branched fluorenyl group having 1 to 10 carbon atoms, and R and 1^ may be the same or different from each other.

The invention has the advantages that the preparation of the magnesium-aluminum hydrotalcite solid base catalyst of the invention is simple, It is low in cost and high in stability, activity and selectivity, and is suitable for catalyzing various amidation reactions of esters and ethanolamines. Moreover, the reaction product obtained by the amidation reaction is a sterol amide compound, has good surface activity, is one of the most important varieties of nonionic surfactants, and is an important active monomer in modern synthetic detergents, and is widely used. In detergents, foam stabilizers, thickeners, softeners, rust inhibitors and antistatic agents. DRAWINGS

1 is a magnesium-aluminum-based hydrotalcite precursor prepared by the nucleation/crystallization method of Example 1 and having a magnesium-aluminum ratio of 2:1 and a magnesium-aluminum obtained by calcining and rehydrating (a). XRD pattern of hydrotalcite solid base catalyst (b);

2 is a magnesium-aluminum-based hydrotalcite precursor prepared by the nucleation/crystallization separation method of Example 3, and a magnesium-aluminum-based hydrotalcite precursor (a) obtained by calcining and rehydrating (a). XRD pattern of hydrotalcite solid base catalyst (b);

3 is a magnesium-aluminum-based hydrotalcite precursor prepared by the nucleation/crystallization separation method of Example 4, and a magnesium-aluminum-based hydrotalcite precursor (a) obtained by calcining and rehydrating (a). XRD pattern of hydrotalcite solid base catalyst (b);

4 is a magnesium-aluminum-based hydrotalcite precursor (a) prepared by the urea method of Example 2 and having a magnesium-aluminum ratio of 2:1 and a magnesium-aluminum hydrotalcite solid base catalyst obtained by calcining and rehydrating (a). (b) XRD diagram.

Figure 5 is a magnesium-aluminum-based hydrotalcite precursor (a) prepared by the nucleation/crystallization method of Example 5 having a magnesium-aluminum ratio of 2:1 and after (a) calcination and rehydration (with stirring) The XRD pattern of the obtained magnesium-aluminum hydrotalcite solid base catalyst (b). detailed description

The invention is specifically illustrated by the following examples. In the following examples, the following methods were used to determine the production according to the present invention obtained in each of the examples.

P

ΒΠ:

The structure was analyzed by a Shimadzu XRD-6000 X-ray diffractometer, Cu Ka source (λ = 0.154 nm), voltage 40 Kv, current 30 mA, continuous scanning, scanning speed 2 min.

LC system: ProStar 210/215 solvent delivery system, column C18 column

(4.6x 150mm) ). The Varian Prostar 325 UV detector and the Varian LC station in the United States, V6.2 chromatographic data processing system detect and process chromatographic data. A chromatogram of stearyl monoethanolamine and methyl stearate was obtained.

Detection conditions of methyl stearate: Flow rate: 1.0 mL/min _; Detection wavelength: 210 nm _; Injection volume: 20 L, column temperature 40 ° C, Mobile phase: Gradient elution, phase A is acetonitrile: water ( Volume ratio 85:

15), phase B is acetonitrile, and the gradient elution procedure is shown in Table 1.

Table 1 Gradient elution procedure

Time (min) flow rate (mL/min) A (%) B (%)

0 1 100 0

8 1 100 0

18 1 0 100

28 1 0 100 Example 1

Prepare 250 ml of mixed salt solution of magnesium nitrate and aluminum nitrate with deionized water, wherein the concentration of magnesium ion is 0.8 mol/L, the concentration of aluminum ion is 0.4 mol/L _, and 250 ml of sodium hydroxide and carbonic acid are prepared. The mixed alkaline solution of sodium is such that the concentration of sodium hydroxide in the mixed alkaline solution obtained is 1.9 mol/L, and the concentration of sodium carbonate is 0.8 mol/L. After the above mixed salt solution and the mixed alkaline solution were ultrasonically dispersed for 10 min, the above two mixed solutions were dropwise added to the colloid mill at 25 ° C, and mixed for several minutes. The reaction conditions included: the voltage was 140 V, The rotation speed was 4500 rpm, and the reaction time was 2-3 min. After the reaction was completed, the obtained slurry was transferred into a 1000 ml three-necked flask, and recrystallized at 95 ° C for 5 hours, and the obtained product was centrifuged with deionized water. To a pH between 7 and 8, then dried at 100 ° C for 24 h, ground in a nitrogen-protected atmosphere furnace at room temperature of 10 ° C / min The temperature was raised to 500 ° C and calcined for 15 hours. Then, 100 ml of water with CO ₂ removed was rehydrated under nitrogen for 8 hours. After rapid filtration, it was vacuum dried at 40 ° C for 24 hours. The magnesium aluminum hydrotalcite solid base catalyst of the present invention is obtained.

It was confirmed by XRD pattern characterization that the chemical composition of the obtained magnesium-aluminum hydrotalcite solid base catalyst was [Mg ₂ Al(OH ) ₆ ](ΟΗ ) · 2H

Catalytic reaction of esters with ethanolamine: 14.925 g of methyl stearate, 3.36 g of monoethanolamine and 0.915 g of magnesium aluminum hydrotalcite solid base catalyst prepared as described above were weighed into a 100 ml three-necked flask. After reacting for 4 hours in a 140 ° C oil bath, a sample was taken for liquid phase high performance liquid chromatography analysis, and the result showed that the conversion ratio of methyl stearate was 92.2%.

Example 2

In a 100 ml Teflon container or glass container, dissolve Mg(N0 ₃ ) ₂ · 63⁄40 and A1(N0 ₃ ) ₃ · 93⁄40 in a molar ratio of 2:1 in 75 ml of deionized water to make a total A mixed salt solution with a concentration of 0.3 M. Add urea to the above mixed salt solution in a molar ratio of urea: N0 ₃ = 4.0, dissolve it, seal the container, and react at a constant temperature of 90 ° C for 3 days. After the solution is cooled to 20 ° C, filter and use deionized water. The obtained white precipitate was washed to pH 7-8, and dried at 100 ° C for 24 h to obtain a magnesium aluminum carbonate hydrotalcite precursor, ground, and placed in a nitrogen atmosphere atmosphere furnace at room temperature at 10 ° C / min. The temperature was raised to 500 ° C and calcined for 15 hours. Then, 100 ml of water with CO ₂ removed was rehydrated under nitrogen for 8 hours, and then rapidly filtered and vacuum dried at 40 ° C for 24 hours. The magnesium aluminum hydrotalcite solid base catalyst of the present invention.

The amidation reaction and analysis of the catalyzed esters and ethanolamine were carried out in the same manner as in Example 1, except that the catalyst used was the magnesium-aluminum hydrotalcite solid base catalyst prepared in the present example, and the results showed that stearic acid The conversion of methyl ester was 89.4%.

Example 3 Prepare 250 ml of mixed salt solution of magnesium nitrate and aluminum nitrate with deionized water, wherein the concentration of magnesium ion is 1.2 mol/L, the concentration of aluminum ion is 0.4 mol/L _, and 250 ml of sodium hydroxide and carbonic acid are prepared. The mixed alkaline solution of sodium is such that the concentration of sodium hydroxide in the mixed alkaline solution obtained is 2.56 mol/L, and the concentration of sodium carbonate is 0.8 mol/L. After the above mixed salt solution and the mixed alkaline solution were ultrasonically dispersed for 10 min, the above two mixed solutions were dropwise added to the colloid mill at a temperature of 25 ° C, and mixed for several minutes. The reaction conditions included: The voltage was 140 V , the rotation speed is 4500 rpm, the reaction time is 2-3 min. After the reaction is finished, the obtained slurry is transferred into a 1000 ml three-necked flask, and recrystallized at 95 ° C for 5 hours, and the obtained product is centrifuged with deionized water. Wash to a pH between 7 and 8, then dry at 100 ° C for 24 h, grind and place in a nitrogen-protected atmosphere furnace from room temperature at 30 ° C / min to 500 ° C for 15 hours, then The magnesium-alumina-based hydrotalcite solid base catalyst of the present invention was prepared by placing 100 ml of water in which CO ₂ was removed and rehydrating under nitrogen for 8 hours, and rapidly vacuuming and drying at 40 ° C for 24 hours.

The amidation reaction and analysis of the catalyzed esters and ethanolamine were carried out in the same manner as in Example 1, except that the catalyst used was the magnesium-aluminum hydrotalcite solid base catalyst prepared in the present example, and the results showed that stearic acid The conversion of acid methyl ester was 96.3%.

Example 4

Prepare 250 ml of mixed salt solution of magnesium nitrate and aluminum nitrate with deionized water, wherein the concentration of magnesium ion is 0.8 mol/L, the concentration of aluminum ion is 0.2 mol/L; and 250 ml of sodium hydroxide and carbonic acid are prepared. mixed alkaline solution of sodium, mixing an alkaline solution of sodium hydroxide to give a concentration of 1.6 mol / L, the concentration of sodium carbonate of 0.4 mol / L ₀ to the mixed salt solution and mixed alkaline solution ultrasonic dispersion 10 After min, the above two mixed solutions are added dropwise to the colloid mill at 25 ° C, and mixed for several minutes. The reaction conditions include: voltage is 140V, rotation speed is 4500 rpm, reaction time is 2-3 min, and the reaction is over. Thereafter, the obtained slurry was transferred into a 1000 ml three-necked flask, and recrystallized at 95 ° C for 5 hours, and the obtained product was centrifugally washed with deionized water to a pH of between 7 and 8, and then at 100 °. C dry for 24 h, grind and place in a nitrogen-protected atmosphere furnace from room temperature to 30 The temperature was raised to 500 ° C for 15 hours at a rate of ° C / min, and then re-hydrated in 100 ml of water with CO ₂ removed for 8 hours under nitrogen protection, and rapidly vacuum filtered and dried under vacuum at 40 ° C for 24 hours. That is, the magnesium-aluminum hydrotalcite solid base catalyst of the present invention is prepared.

The amidation reaction and analysis of the catalyzed esters and ethanolamine were carried out in the same manner as in Example 1, except that the catalyst used was the magnesium-aluminum hydrotalcite solid base catalyst prepared in the present example, and the results showed that stearic acid The conversion of methyl ester was 95.0%.

Example 5

Prepare 250 ml of mixed salt solution of magnesium nitrate and aluminum nitrate with deionized water, wherein the concentration of magnesium ion is 0.8 mol/L, the concentration of aluminum ion is 0.4 mol/L _, and 250 ml of sodium hydroxide and carbonic acid are prepared. The mixed alkaline solution of sodium is such that the concentration of sodium hydroxide in the mixed alkaline solution obtained is 1.9 mol/L, and the concentration of sodium carbonate is 0.8 mol/L. After the above mixed salt solution and the mixed alkali solution are ultrasonically dispersed for 10 min, the above two mixed solutions are dropwise added to the colloid mill at a temperature of 25 ° C, and mixed for several minutes. The reaction conditions include: the voltage is 140V. , the rotation speed is 4500 rpm, the reaction time is 2-3 min. After the reaction is completed, the obtained slurry is transferred into a 1000 ml three-necked flask, and recrystallized at 95 ° C for 5 hours, and the obtained product is treated with deionized water. Centrifugal washing to pH between 7-8, then drying at 100 ° C for 24 h, grinding and placing in a nitrogen-protected atmosphere furnace from room temperature at 10 ° C / min to 500 ° C and then roasting for 15 hours Then, 100 ml of water in which C0 ₂ was removed was rehydrated under nitrogen for 8 hours, and the rehydration was accompanied by stirring at 400 r/min. After rapid filtration and vacuum drying at 40 ° C for 24 hours, the magnesium aluminum hydrotalcite solid base catalyst of the present invention was prepared.

The amidation reaction and analysis of the catalyzed esters and ethanolamine were carried out in the same manner as in Example 1, except that the catalyst used was the magnesium-aluminum hydrotalcite solid base catalyst prepared in the present example, and the results showed that stearic acid The conversion of methyl ester was 87.1%.

Claims

Claim

A magnesium-aluminum hydrotalcite solid base catalyst for synthesizing a sterol amide compound, characterized in that the catalyst has the following chemical formula:

[Mg _1-x Al _x (OH ) ₂ ] ^x+ (OH ) _x · m3⁄40

Where x is in the range of 0.2 x 0.33, m is the amount of crystal water;

The magnesium aluminum hydrotalcite solid base catalyst is prepared by calcining and rehydrating a magnesium aluminum hydrotalcite precursor having the following chemical formula:

[Mg _1-x Al _x (OH ) ₂ ] ^X+ (C0 ₃ ² ) _χ/2 · n3⁄40,

Where x has a value range of 0.2 x 0.33, where n is the amount of crystal water.

The catalyst according to claim 1, wherein the m and !! respectively satisfy: 0.1 < m < 10 and 0.1 < n < 10.

3. A method of preparing a catalyst according to claim 1, characterized in that the method comprises the steps of:

(1) preparing the magnesium-aluminum hydrotalcite precursor:

(2) Preparation of magnesium-aluminum composite metal oxides, including:

The magnesium-aluminum hydrotalcite precursor prepared in the step (1) is placed in a nitrogen-protected atmosphere furnace and heated at room temperature at a temperature increase rate of 1 to 50 ° C/min to 100 to 1000 ° C, followed by calcination and calcination. The time is 1-50 hours, after the completion of the calcination, it is naturally cooled to room temperature, and the obtained product is the magnesium-aluminum composite metal oxide;

(3) preparing the magnesium-aluminum hydrotalcite solid base catalyst, comprising:

The magnesium-aluminum composite metal oxide obtained in the step (2) is placed in water in which CO ₂ is removed, and rehydrated under a nitrogen atmosphere. The rehydration time is 1 to 50 hours, and then the product is subjected to a product. Rapidly suction filtration, and then drying in a vacuum drying oven at 10-80 ° C for 5 to 48 hours, during the rehydration process, adding 20-200 ml per gram of the magnesium-aluminum composite metal oxide is removed. The water of C0 ₂ , the obtained product is the magnesium-aluminum hydrotalcite solid base catalyst, and the catalyst has Lower chemical formula:

[Mg _1-x Al _x (OH ) ₂ ] ^x+ (OH ) _x · m3⁄40,

Among them, x has a value range of 0.2 x 0.33, and m is the amount of crystal water.

4. The method according to claim 3, wherein the method of preparing the magnesium aluminum-based hydrotalcite precursor in the step (1) comprises preparing by a nucleation/crystallization separation method or a urea method.

5. The method of claim 4, wherein the nucleation/crystallization isolation method comprises:

A. preparing a mixed salt solution of a divalent soluble magnesium salt and a trivalent soluble aluminum salt, wherein the divalent metal magnesium has an ion concentration of 0.12-12 mol/L, and the ion of the divalent metal magnesium and the ion of the trivalent metal aluminum Molar ratio is 2-4;

B. preparing a mixed alkaline solution of a base and a soluble inorganic salt, the concentration of the alkali in the obtained mixed alkaline solution is 0.096-9.6 mol/L, and the molar ratio of the base to the soluble inorganic salt is 2.4. -3.2, the base is sodium hydroxide and / or potassium hydroxide, the soluble inorganic salt is sodium and / or potassium carbonate;

D. The mixed salt solution prepared in the step A and the mixed alkaline solution prepared in the step B are added dropwise to the colloid mill at 5 to 70 ° C, mixed for several minutes, and then transferred into a three-necked bottle. The reaction is carried out at 10 ° C - 100 ° C for 4 to 100 hours to obtain a slurry of the magnesium aluminum hydrotalcite precursor;

E. The slurry of the magnesium-aluminum hydrotalcite precursor obtained in the step D is subjected to centrifugal washing several times to a pH of 7-8, and then dried at 10 to 120 ° C for 24 hours to obtain the magnesium. Aluminum hydrotalcite precursor.

6. A method according to claim 5, wherein said base in said step B is sodium hydroxide; said soluble inorganic salt being sodium carbonate.

7. The method according to claim 4, wherein the urea method comprises:

A. preparing a mixed salt solution of a divalent soluble magnesium salt and a trivalent soluble aluminum salt, wherein The metal magnesium has an ion concentration of 0.12-12 mol/L, and the molar ratio of the divalent metal magnesium ion to the trivalent metal aluminum ion is 2-4;

C. Prepare a 0.1-5 mol/L urea solution;

The method according to any one of claims 5-7, wherein the divalent soluble magnesium salt in the step A is magnesium nitrate, magnesium sulfate, magnesium acetate or magnesium chloride; The trivalent soluble aluminum salt is aluminum nitrate, aluminum sulfate, aluminum acetate or aluminum chloride.

The method according to any one of claims 3 to 7, wherein the magnesium-aluminum hydrotalcite precursor has the following chemical formula:

[Mg _1-X A1 _X (0H )2] ^X+ (C0 ₃ ² ) _χ/2 · n3⁄40,

10. The method according to claim 9, wherein the n satisfies 0.1 < n < 10.