A metal oxide modified MgO-SiO2 solid base catalyst, a preparation method and application thereof

Abstract

The application belongs to the technical field of isomer separation, and particularly relates to a metal oxide modified MgO-SiO2 solid alkali catalyst, a preparation method and application thereof. The metal oxide modified MgO-SiO2 solid alkali catalyst is prepared first, and under the catalyst, the secondary ester in dodecanol ester isomers reacts with acid or acyl chloride as much as possible, and the reaction of the hydroxyl on the primary ester is reduced as much as possible. After the dodecanol ester formed by the reaction is separated, the content of the primary ester in the dodecanol ester is naturally obviously improved. There are a large number of basic centers on the surface of the catalyst, the steric hindrance of the hydroxyl on the secondary ester is small, the secondary ester is more easily combined with the basic centers on the surface of the carrier and subjected to subsequent reaction, and the steric hindrance of the hydroxyl on the primary ester is large, so the primary ester is not easily adsorbed on the basic centers of the catalyst, thereby reducing the reaction probability of the primary ester.

Description

Technical Field

[0001] This invention belongs to the field of isomer separation technology, and specifically relates to a metal oxide modified MgO-SiO2 solid base catalyst, its preparation method and application. Background Technology

[0002] Dodecyl alcohol ester (CS-12), also known as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, is a green and environmentally friendly film-forming aid for water-based coatings. It is widely used due to its low freezing point and high boiling point. Industrially, it is mainly produced by reacting isobutyraldehyde as a raw material under the action of a liquid alkali. Dodecyl alcohol ester is composed of two isomers: a primary ester and a secondary ester.

[0003] Its structure is as follows:

[0004] Primary ester (SM1)

[0005]

[0006] Secondary ester (SM3)

[0007]

[0008] Analysis results show that the ratio of primary esters to secondary esters in industrially produced dodecyl alcohol esters is approximately 1.5, that is, the content of primary esters is approximately 60%, while the content of secondary esters is approximately 40%. Research results indicate that when the content of primary esters in dodecyl alcohol esters is higher, the film-forming performance is better (Process and Equipment, 2017, 43(9), 76-78).

[0009] Currently, some reports suggest using isobutyraldehyde as a raw material and employing alkaline ionic liquid catalysts or solid alkaline catalysts instead of industrially used liquid alkaline catalysts to increase the content of primary esters in dodecyl alcohol esters. However, since the reactivity of alkaline ionic liquid catalysts or solid alkaline catalysts is lower than that of liquid catalysts, and the preparation cost of alkaline ionic liquid catalysts is high, their industrial application is relatively unlikely. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a method for preparing a metal oxide-modified MgO-SiO2 solid base catalyst:

[0011] (1) After fully dispersing F127 in a mixed solvent of ethanol and water, the resulting mixture is adjusted to be acidic;

[0012] (2) Prepare a solution by mixing the magnesium salt and the metal oxide salt with a molar ratio of metal element in the metal oxide to magnesium element in the magnesium salt of 0.01 to 0.1, and then thoroughly mix the solution with the mixture obtained in step (1).

[0013] (3) Add sodium silicate to the mixed system obtained in step (2) and hydrolyze it completely. Then, carry out a hydrothermal reaction on the hydrolyzed system. After the reaction is completed, filter the resulting reaction system, retain the filter cake, wash and dry it, and then calcine it in a protective atmosphere at 400-800℃ and in air at 500℃ to obtain a MgO-SiO2 solid base catalyst modified with metal oxides with a MgO mass percentage of 5-20%.

[0014] As a preferred option: In step (1), after F127 is fully dispersed in a mixed solvent of ethanol and water at a mass concentration of 3% to 10%, concentrated hydrochloric acid is added dropwise to adjust the resulting mixture to acidity, and the amount of concentrated hydrochloric acid is 10% to 50% of the mass of F127.

[0015] Preferably, in step (2), the salt of the metal oxide is cerium nitrate, aluminum nitrate, zinc nitrate, or manganese nitrate.

[0016] As a preferred option: in step (3), the hydrothermal reaction is carried out at 80-120°C for 24 hours.

[0017] As a preferred option: in step (3), the filter cake is retained and washed, and then dried at 100°C for 12 hours.

[0018] As a preferred option: in step (3), the calcination time in a protective atmosphere is 6 hours and the calcination time in air is 5 hours.

[0019] The present invention also provides a metal oxide modified MgO-SiO2 solid base catalyst obtained by the above preparation method.

[0020] This invention also provides an application of the above-mentioned metal oxide-modified MgO-SiO2 solid base catalyst in increasing the primary ester content in dodecyl alcohol esters:

[0021] Dodecyl alcohol ester is reacted with carboxylic acid and / or alkyl acyl chloride at 80–160 °C under the condition of MgO-SiO2 solid base catalyst modified with metal oxide. The reaction product is then separated from the dodecyl alcohol ester by distillation, leaving the dodecyl alcohol ester with increased primary ester content.

[0022] As a preferred option, the amount of the metal oxide-modified MgO-SiO2 solid base catalyst is 1 to 5% of the mass of the dodecyl alcohol ester.

[0023] As a preferred option, the reaction is carried out at atmospheric pressure.

[0024] As a preferred option, the reaction time is 1 to 8 hours.

[0025] Preferably, the carboxylic acid is isobutyric acid, the alkyl acyl chloride is isobutyryl chloride, and the amount of carboxylic acid and / or alkyl acyl chloride is 100% of the amount of dodecyl alcohol ester.

[0026] The beneficial effects of this invention are as follows: First, considering that in the isomers of dodecyl alcohol esters, the hydroxyl group (-OH) on the secondary ester is primary, and the hydroxyl group on the primary ester is secondary, the steric hindrance of the secondary hydroxyl group is greater than that of the primary hydroxyl group. From a kinetic perspective, when reacting with acids or acyl chlorides, the primary hydroxyl group (-OH) on the secondary ester reacts more readily. Therefore, this application employs a chemical reaction method, controlling the reaction conditions to allow the secondary ester in the dodecyl alcohol ester isomers to react with acids or acyl chlorides, while minimizing the reaction of the hydroxyl group on the primary ester. Finally, after separating the product formed by the reaction (hexadecyl diester), the content of the primary ester in the remaining dodecyl alcohol ester is naturally increased. Furthermore, the hexadecyl diester generated by this reaction is also a product of significant value, which, from another perspective, improves the utilization value of dodecyl alcohol ester. The reaction formula is as follows:

[0027]

[0028] Secondly, regarding the selection of catalyst, this application found that liquid base catalysts are unsuitable for the reaction of dodecyl alcohol esters and acids (acyl chlorides). On the one hand, primary and secondary esters interconvert under liquid base catalyst conditions; even if the secondary ester reacts, some of the primary ester will still be converted to the secondary ester. On the other hand, liquid bases are too reactive; although secondary esters react more readily, primary esters will still be converted. To address this, this scheme designs a macroporous solid base catalyst with numerous basic centers on its surface. The hydroxyl groups on the secondary ester of the dodecyl alcohol ester isomers have less steric hindrance, making it easier for them to stably bind to the basic centers on the support surface and proceed with subsequent reactions. Primary esters, due to the greater steric hindrance of their hydroxyl groups, are less likely to adsorb onto the basic centers of the catalyst, thus reducing the reaction probability of primary esters. Simultaneously, the macroporous structure imparted to the catalyst by using F127 as a template agent facilitates the rapid diffusion of primary esters from the catalyst, resulting in a short residence time within the pores and reducing the probability of contact with the basic centers, further decreasing the reaction probability of primary esters.

[0029] During catalyst preparation, magnesium oxide is uniformly dispersed within silica, meaning it is embedded in the pore walls of the silica. During high-temperature calcination, the silica acts as a barrier, preventing the magnesium oxide particles from sintering. This results in highly dispersed and numerous basic centers in the catalyst, leading to high reactivity. Simultaneously, another metal oxide is added to modify the MgO-SiO2 composite oxide. During high-temperature calcination, this metal oxide modifies the basic centers both structurally and electronically, making the MgO basic centers more stable, increasing electron cloud density, and enhancing basicity, thus resulting in even higher reactivity. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of protection of the invention.

[0031] Example 1

[0032] (1) At room temperature (25℃, the same below), 10g of F127 is fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol and water is 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% is added dropwise and stirred for another 2 hours.

[0033] (2) At room temperature, 10g of magnesium nitrate (Mg(NO3)2·6H2O) and 0.8g of cerium nitrate (Ce(NO3)3·6H2O) are dissolved together in 10ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (1) under strong stirring;

[0034] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain CeO2 modified MgO-SiO2 solid base catalyst.

[0035] 50g of dodecyl alcohol ester (primary ester content of 60.8% and secondary ester content of 39.2% are the same below) and 20g of isobutyric acid were added to a three-necked flask, and 2g of CeO2-modified MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0036] Example 2

[0037] (1) At room temperature, 10g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0038] (2) At room temperature, 10g of magnesium nitrate (Mg(NO3)2·6H2O) and 0.8g of cerium nitrate (Ce(NO3)3·6H2O) are dissolved together in 10ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (1) under strong stirring;

[0039] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain CeO2 modified MgO-SiO2 solid base catalyst.

[0040] 50g of dodecyl alcohol ester and 24g of isobutyryl chloride were added to a three-necked flask, and 2g of CeO2-modified MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0041] Example 3

[0042] (1) At room temperature, 15g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 4mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0043] (2) At room temperature, dissolve 10g magnesium nitrate (Mg(NO3)2·6H2O) and 0.5g manganese nitrate (Mn(NO3)2·4H2O) together in 10ml of water to prepare a solution, and add it dropwise to the mixed system obtained in step (1) under strong stirring;

[0044] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain the MnO2 modified MgO-SiO2 solid base catalyst.

[0045] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, and 2g of the MnO2-modified MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0046] Example 4

[0047] (1) At room temperature, 10g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0048] (2) At room temperature, 15g of magnesium nitrate (Mg(NO3)2·6H2O) and 0.8g of cerium nitrate (Ce(NO3)3·6H2O) are dissolved together in 10ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (1) under strong stirring;

[0049] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain CeO2 modified MgO-SiO2 solid base catalyst.

[0050] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, and 2g of CeO2-modified MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0051] Blank comparison example

[0052] No catalyst was added; all other operations were the same as in Example 1.

[0053] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, mixed thoroughly, and reacted at 140℃ for 5 hours. Samples were then taken for analysis, and the results are shown in Table 1.

[0054] Comparative Example 1

[0055] Without the addition of cerium nitrate, all other operations were the same as in Example 1:

[0056] (1) At room temperature, 10g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0057] (2) At room temperature, dissolve 10g of magnesium nitrate (Mg(NO3)2·6H2O) in 10ml of water to prepare a solution, and add it dropwise to the mixed system obtained in step (1) under strong stirring;

[0058] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined in air at 500℃ for 5 hours to obtain MgO-SiO2 solid base catalyst.

[0059] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, and 2g of the MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0060] Comparative Example 2

[0061] Magnesium nitrate was not added; all other operations were the same as in Example 1.

[0062] (1) At room temperature, 10g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0063] (2) At room temperature, 0.8g of cerium nitrate (Ce(NO3)3·6H2O) was dissolved in 10ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (1) under strong stirring;

[0064] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain CeO2 modified SiO2 solid base catalyst.

[0065] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, and 2g of the CeO2-modified SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140°C for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0066] Comparative Example 3

[0067] The amounts of magnesium nitrate and cerium nitrate added were varied, while all other operations remained the same as in Example 1:

[0068] (1) At room temperature, 10g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0069] (2) At room temperature, 40g of magnesium nitrate (Mg(NO3)2·6H2O) and 2g of cerium nitrate (Ce(NO3)3·6H2O) are dissolved together in 10ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (1) under strong stirring;

[0070] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain CeO2 modified MgO-SiO2 solid base catalyst.

[0071] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, and 2g of CeO2-modified MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0072] Comparative Example 4

[0073] Calcium nitrate was used instead of magnesium nitrate, and all other operations were the same as in Example 1:

[0074] (1) At room temperature, 10g of F127 was fully dispersed in 200ml of a mixed solvent of ethanol and water (the mass ratio of ethanol to water was 1:1) and stirred for 2 hours. Then, 2mL of concentrated hydrochloric acid with a mass concentration of 37% was added dropwise and stirred for another 2 hours.

[0075] (2) At room temperature, 9.2g of calcium nitrate (Ca(NO3)2·4H2O) and 0.8g of cerium nitrate (Ce(NO3)3·6H2O) are dissolved together in 10ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (1) under strong stirring;

[0076] (3) At room temperature, 20g of sodium silicate is dissolved in 20ml of water to prepare a solution, and then added dropwise to the mixed system obtained in step (2) under strong stirring. After the addition is completed, stirring is continued for 5 hours. Then, the resulting stirred system is transferred to an autoclave and left to stand at 120℃ for 24 hours. The resulting reaction system is filtered, the filter cake is retained and washed, dried at 100℃ for 12 hours, calcined at 600℃ for 6 hours under nitrogen protection, and then calcined at 500℃ for 5 hours in air to obtain CeO2 modified MgO-SiO2 solid base catalyst.

[0077] 50g of dodecyl alcohol ester and 20g of isobutyric acid were added to a three-necked flask, and 2g of CeO2-modified MgO-SiO2 solid base catalyst prepared in this example was added to it. After mixing thoroughly, the mixture was reacted at 140℃ for 5 hours and then sampled for analysis. The results are shown in Table 1.

[0078] Table 1: Mass percentages of primary ester, secondary ester, and hexadecyl diester in the reaction products

[0079] Primary esters Secondary esters Hexadecyl diester Primary ester: Secondary ester Example 1 53.5％ 21.6％ 24.9％ 71.2：28.8 Example 2 40.2％ 14.7％ 45.1％ 73.2：26.8 Example 3 54.6％ 25.2％ 20.2％ 68.4：31.6 Example 4 49.8％ 18.8％ 31.4％ 72.5：27.5 Blank comparison example 57.1％ 31.7％ 11.2％ 64.3：35.7 Comparative Example 1 54％ 27.8％ 18.2％ 66：34 Comparative Example 2 55.7％ 29.3％ 15％ 65.5：34.5 Comparative Example 3 32.8％ 17.6％ 49.6％ 65.1：34.9 Comparative Example 4 35.5％ 18.5％ 46％ 65.7：34.3

[0080] In the 50g dodecyl alcohol ester used as raw material, the primary ester content was 60.8% (i.e., 30.4g) and the secondary ester content was 39.2% (i.e., 19.6g). In the blank control example in Table 1, isobutyric acid was introduced into the reaction. After the reaction, the ratio of primary ester content to secondary ester content in the raw material increased. This is because the hydroxyl groups on the secondary ester react more readily with isobutyric acid than those on the primary ester, resulting in a greater reduction of secondary ester content in the raw material after the reaction. Consequently, the proportion of primary ester in the remaining dodecyl alcohol ester raw material increased accordingly. However, without a catalyst, the reaction was slow, and the degree of conversion was limited.

[0081] In the embodiments listed in Table 1, after the raw materials were treated with the catalyst, not only was the degree of reaction conversion significantly increased, but the ratio of primary ester content to secondary ester content also increased substantially. This is because the solid base catalyst prepared and used in this scheme provides base active centers for the reaction, promoting the occurrence of the reaction. Furthermore, the catalyst surface has a large number of basic centers. The secondary ester in the dodecyl alcohol ester isomer has less steric hindrance and is more likely to stably combine with the basic centers on the support surface and undergo subsequent reactions. The primary ester, due to the greater steric hindrance of its hydroxyl groups, is less likely to adsorb onto the basic centers of the catalyst, thus reducing the reaction probability of the primary ester. Simultaneously, the macroporous structure of the catalyst facilitates the rapid diffusion of the primary ester from the catalyst, resulting in a shorter residence time within the pores and reducing the probability of contact with the basic centers, further reducing the reaction probability of the primary ester and improving the product quality of the dodecyl alcohol ester. However, in contrast, when isobutyryl chloride was used as a reactant in Example 2, its activity was relatively high. Although the ratio of primary ester content to secondary ester content in the product after reaction treatment was higher, a larger amount of hexadecyl diester was generated, reducing the yield of the dodecyl alcohol ester.

[0082] From the comparative examples in Table 1, it can be seen that the catalyst without magnesium oxide has low reaction activity (Comparative Example 2), while the catalyst without cerium oxide modification has relatively low basicity and insufficient reaction activity (Comparative Example 1). Increasing the content of magnesium oxide and cerium oxide makes the catalyst too basic, which increases the overall reaction activity and produces a higher content of hexadecyl diester. At the same time, the interconversion between primary and secondary esters is accelerated, so that the ratio of primary ester content to secondary ester content does not change much (Comparative Example 3). Replacing magnesium oxide with calcium oxide yields similar results to Comparative Example 3.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of a metal oxide modified MgO-SiO2 solid base catalyst, characterized by: The preparation method is, (1) after F127 is fully dispersed in a mixed solvent of ethanol and water, the obtained mixed system is adjusted to be acidic; (2) a solution of a magnesium salt and a salt of a metal oxide is prepared according to a molar ratio of the metal element in the metal oxide to the magnesium element in the magnesium salt being 0.01-0.1, and the solution is fully mixed with the mixed system obtained in step (1), (3) sodium silicate is added to the mixed system obtained in step (2) and fully hydrolyzed, then the obtained hydrolysis system is subjected to hydrothermal reaction at 80-120 DEG C, after the reaction is completed, the obtained reaction system is filtered, the filter cake is retained and washed and dried, then is sequentially subjected to calcination in a protective atmosphere at 400-800 DEG C and calcination in air at 500 DEG C, thereby obtaining a metal oxide modified MgO-SiO2 solid base catalyst with MgO mass percentage being 5-20%, In step (2), the salt of the metal oxide is cerous nitrate or manganous nitrate.

2. The method for preparing a metal oxide-modified MgO-SiO2 solid base catalyst according to claim 1, characterized by: In step (1), after F127 is fully dispersed in a mixed solvent of ethanol and water according to a mass concentration of 3%-10%, concentrated hydrochloric acid is added dropwise to the mixed solvent to adjust the obtained mixed system to be acidic, and the amount of the concentrated hydrochloric acid is 10%-50% of the mass of F127.

3. The method for preparing a metal oxide-modified MgO-SiO2 solid base catalyst according to claim 1, characterized by: In step (3), the hydrothermal reaction time is 24 hours, the calcination time in the protective atmosphere is 6 hours, and the calcination time in air is 5 hours.

4. A metal oxide modified MgO-SiO2 solid base catalyst prepared by the preparation method according to any one of claims 1 to 3.

5. Use of a metal oxide modified MgO-SiO2 solid base catalyst according to claim 4 for increasing the primary ester content in dodecanol esters, characterized in that: The application is that dodecanol ester is reacted with carboxylic acid and / or alkyl acid chloride under the condition of the metal oxide modified MgO-SiO2 solid base catalyst at 80-160 DEG C, then the reaction product is separated from the dodecanol ester, thereby leaving dodecanol ester with increased content of primary ester.

6. Use of the metal oxide-modified MgO-Si02 solid base catalyst according to claim 5 for increasing the primary ester content in dodecanol esters, characterized in that: The carboxylic acid is isobutyric acid, and the alkyl acid chloride is isobutyryl chloride.

7. Use of the metal oxide-modified MgO-Si02 solid base catalyst according to claim 5 for increasing the primary ester content in dodecanol esters, characterized in that: The amount of the metal oxide modified MgO-SiO2 solid base catalyst is 1-5% of the mass of the dodecanol ester.

8. Use of the metal oxide-modified MgO-Si02 solid base catalyst according to claim 5 for increasing the primary ester content in dodecanol esters, characterized by: The reaction time is 1-8 hours.

9. Use of the metal oxide-modified MgO-Si02 solid base catalyst according to claim 5 for increasing the primary ester content in dodecanol esters, characterized by: The amount of the carboxylic acid and / or the alkyl acid chloride is 100% of the amount of substance of the dodecanol ester.

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