Application of solid base catalyst in catalytic synthesis of alcohol ester containing high primary ester

Abstract

The present invention relates to the field of catalyst technology, and in particular to the application of a solid base catalyst for catalytic synthesis of an alcohol ester twelve containing a high primary ester, wherein isobutyraldehyde is used as a raw material, 2,2,4-trimethyl-1,3-pentanediol and isobutyric acid are obtained by aldol condensation and Cannizzaro reaction under alkaline catalyst conditions, and then the two are esterified to obtain a product. The advantages of the present invention are: few reaction steps, streamlined process, wide source of reactants, moderate price, easy preparation of catalysts, and large-scale production; the content of the prepared product primary fatty alcohol ester twelve is greater than 70%, meeting the requirements of industrial products; the catalyst is easily separated from the product, meeting environmental protection requirements.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a solid base catalyst for catalytic synthesis of a high primary ester alcohol containing ester dodecahydrate and a preparation method thereof. Background Art

[0002] Alcohol ester twelve, namely dodecanol ester (CS-12), scientific name 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, is an emerging green additive with more and more extensive applications, mainly as a film-forming aid for latex paint, which has received widespread attention. Compared with ordinary film-forming aids, dodecanol ester has many advantages: good resin solubility, small dosage, low film-forming temperature, good film leveling and color development, low freezing point, good hydrolysis stability, low toxicity, and is an excellent latex paint film-forming aid. Alcohol ester twelve is composed of two isomers. The reason is that the two hydroxyl groups of 2,2,4-trimethyl-1,3-pentanediol generated during the reaction are esterified with isobutyric acid respectively, resulting in the formation of isomers. Moreover, the performance and use of these two isomers are the same, so the content of alcohol ester twelve is the sum of the contents of these two isomers. Among them, the higher the content of primary alcohol ester twelve, the more conducive to film formation. Studies have found that primary esters and secondary esters will transform into each other under different acid and base conditions, and the acidity causes the alcohol ester to decompose, while a small amount of base can be beneficial to the stability of the product.

[0003] There are many methods for preparing CS-12 in the prior art. The catalysts used in the current reaction are mostly oxides or hydroxides of alkaline earth metals, among which sodium hydroxide aqueous solution is the most common. The use process of the catalyst is restricted by its concentration and addition amount and is difficult to control. For example, a catalyst for the synthesis of dodecanol ester disclosed in a Chinese patent document (application number CN201310076363.9) is synthesized with a certain weight percentage of sodium hydroxide, calcium hydroxide, barium hydroxide, magnesium hydroxide and zinc hydroxide. The catalyst is directly prepared in the next step of the catalyst. Although the invention has a high conversion rate for the catalytic isobutyraldehyde reaction, the solid catalyst is prepared by material preparation, ball milling and screening in the process, which takes a long time, the steps are cumbersome, and the temperature is difficult to control. In patent CN1325841A, Wang Endong replaced the catalyst for ester synthesis with a hydrate of barium hydroxide, which increased the selectivity of the product from 89% to more than 96%, but the intermediate product still needs to be separated in the process, the steps are cumbersome, and the barium hydroxide catalyst is toxic. James et al. published a method using KOH particles as a catalyst, a reaction temperature of 70-85°C, a feeding time of 2.5 hours, and a residence time of 10 minutes, and obtained a raw material conversion rate of 18.4%. The disadvantages of the process are low raw material conversion rate and many by-products. The present invention uses non-toxic raw materials, has a safe production process, has few by-products, and has a high selectivity for primary alcohol ester dodecahydrate. Summary of the invention

[0004] In view of the shortcomings and disadvantages of the prior art, the present invention provides a solid base catalyst for catalyzing the synthesis of alcohol ester 12 containing high primary esters and a preparation method thereof. The obtained catalyst is not only low in price, but also has the characteristics of high conversion rate, simple preparation scheme, easier separation of product alcohol ester 12 and the ability to produce alcohol ester 12 with high primary ester content, and has good economic efficiency and industrial value. The present invention improves the conversion of primary esters through the active center of the solid base catalyst, and adds sodium hydroxide to increase the stability of primary esters in alcohol ester 12, thereby increasing the content of primary ester alcohol ester 12.

[0005] The catalyst carrier is SBA-15, with CaO, BaO and K2O as the catalyst active centers and molybdenum oxide acting synergistically, the main function of which is to increase the stability of alcohol ester twelve and improve the content of primary ester.

[0006] The present invention adopts the following technical scheme: a preparation method of a solid base catalyst: the catalyst adopts an impregnation method, CaO, BaO and K2O as alkaline active centers and molybdenum oxide are synergistically loaded on a carrier, and a solid base catalyst can be obtained through impregnation, drying and calcination.

[0007] The specific preparation method steps of the solid base catalyst are as follows:

[0008] (1) Take Ca(NO3)2, Ba(NO3)2, KNO3 and ammonium heptamolybdate [(NH4)6Mo7O 24 ] are added to water and mixed to prepare solution A; then NaOH is dissolved in deionized water to prepare solution B; the molar ratio of calcium nitrate: barium nitrate: potassium nitrate is n(Ca):n(Ba):n(K)=1:1:1~1:10:10, the molar ratio of calcium and molybdenum is n(Ca):n(Mo)=1:1~1:10; the molar ratio of Ca and auxiliary sodium is n(Ca):n(Na)=1:1~1:0.1;

[0009] (2) taking the carrier SBA-15 and performing purification and drying treatment, the purification and drying conditions are drying in a drying oven at 100-140° C. for 5-12 hours;

[0010] (3) dripping solution A in step (1) into the carrier in step (2) dropwise, letting stand for 12 hours, then dripping solution B into the carrier loaded with active components, letting stand for 3 hours;

[0011] (4) placing the solid obtained in step (3) into an oven and drying at 100 to 140° C. for 5 to 12 hours to obtain a catalyst precursor;

[0012] (5) The catalyst precursor obtained in step (4) is calcined at 500-700° C. for 5-8 hours to obtain a multi-alkaline catalyst.

[0013] The active components of CaO / BaO / K2O-MoO3 in the SBA-15 loaded CaO / BaO / K2O-MoO3 catalyst account for 1% to 50% of the carrier mass fraction.

[0014] The catalyst obtained by the method of the present invention is used for catalytic synthesis of high primary alcohol ester twelve. The specific steps are as follows: isobutyraldehyde is used as a raw material, a prepared multi-basic catalyst is added, and a synthesis method of step-by-step heating and two-stage reaction is adopted. Under the action of the catalyst, isobutyraldehyde is first condensed under low temperature conditions, the reaction temperature is 20-40°C, and then directly heated and heated, the second stage reaction temperature is 60-90°C, and the reaction pressure keeps the aldehyde in a liquid phase state.

[0015] a. In the presence of a catalyst, slowly add isobutyraldehyde dropwise at 20-40°C for condensation reaction. The reaction time is 2-3 hours. The resulting mixture contains 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0016] b. The mixture in a is directly heated to a high temperature and subjected to condensation reaction at 60-90°C for 2-10 hours to generate a second stage product mainly containing 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0017] c. The product described in b is separated and recovered by vacuum distillation 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0018] The reaction is carried out in a 500 ml bottle with a stirring, condensing and reflux device, and the amount of catalyst used is 0.1 to 1.2 g. The specific reaction equation for the reaction of isobutyraldehyde to primary ester alcohol ester twelve is:

[0019]

[0020] Beneficial Effects

[0021] (1) SBA-15 silica is a hexagonal ordered mesoporous material. Due to its large pore size, high specific surface area and extremely high stability, it is considered to be a good carrier for heterogeneous catalysts. Using metal oxides as active centers can greatly reduce the preparation cost of catalysts. Supported metal oxide catalysts have received extensive attention in industrial catalytic oxidation. The carrier disperses and enhances the catalytic activity of the active metal oxide on its surface, resulting in a higher conversion rate of isobutyraldehyde. The esterification reaction between the two then results in a higher catalytic efficiency of the product. The presence of sodium hydroxide promotes conversion, stabilizes primary esters, and increases the content of primary ester alcohol ester twelve.

[0022] (2) In heterogeneous bases, calcium-based catalysts are promising catalysts due to their high activity and low cost. Potassium can produce some uniform catalytic activity during the catalytic process, and CaO mixed oxides are designed to reduce leaching through the interaction of CaO with other oxides. CaO / BaO / K2O-MoO3 metal oxides are loaded on SBA-15 as active centers, which are strong base sites that help the reaction. MoO3 has a wide range of band gap tunability, unique semiconductor structure and multivalent states, and can be used as a highly active metal oxide catalyst. The CaO / BaO / K2O-MoO3 catalyst is highly reusable and more conducive to the esterification reaction. In addition, BaO is more conducive to the formation of primary alcohol ester twelve in the reaction.

[0023] (3) The solid reaction between CaO and MoO3 can improve the stability of solid catalysts because this interaction can reduce the leaching of catalyst components. Through this interaction, the dispersion of calcium species on the mesoporous silica support can be used to improve the stability of calcium-based catalysts. After calcining the catalyst, the acid-base interaction between the basic CaO and acidic MoO3 in the catalyst is expected to promote a highly stable dispersion of catalytic active sites, thereby ultimately improving the stability of the catalyst. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with embodiments, but is not limited thereto.

[0025] Example 1

[0026] Catalyst preparation: SBA-15 loaded CaO / BaO / K2O-MoO3 mesoporous catalyst was prepared by impregnation method. First, the water absorption rate of SBA-15 was determined, then 1g SBA-15 was accurately weighed, dried at 100℃, and used as a carrier; then 0.11g Ca(NO3)2, 0.18g Ba(NO3)2, 0.06g KNO3 and 0.16g [(NH4)6Mo7O 24 ] was dissolved in 10 ml of deionized water to obtain a solution. The solution was allowed to stand for half an hour, and then dripped dropwise into the prepared SBA-15 for equal volume impregnation, and then sealed and placed at room temperature for 12 hours, and then moved into a 100°C oven for drying. 0.12 g of NaOH was dissolved in 5 ml of deionized water to obtain a solution, and then dripped dropwise into the above-treated catalyst precursor for equal volume impregnation, and then sealed and placed at room temperature for 3 hours, and then moved into a 100°C oven for 5 hours for drying to obtain a catalyst precursor, which was calcined at 550°C for 6 hours. A solid base catalyst with a mass fraction of 20% of the catalyst active component was obtained (the loading amount can be calculated based on the amount of the initial material).

[0027] Weigh 0.5g of the catalyst and 16g of isobutyraldehyde, first carry out the aldol condensation reaction at a low temperature of 20°C for 2h, then raise the temperature to 60°C for Cannizzaro reaction for 2h. The reaction is carried out in a three-necked flask equipped with a thermometer and a condensation reflux device, heated in a water bath, and magnetically stirred. Finally, the reaction product is taken out and analyzed by gas chromatography.

[0028] Example 2

[0029] 0.09 g Ba(NO3)2 was used to replace 0.18 g Ba(NO3)2 in Example 1, and the other steps were the same as those in Example 1.

[0030] Example 3

[0031] Use 0.05gCa(NO3)2 to replace 0.11gCa(NO3)2 in Example 1, and the other steps are the same as Example 1.

[0032] Example 4

[0033] 0.08 g [(NH4)6Mo7O 24 ] instead of 0.16 g [(NH4)6Mo7O 24 ], other steps are the same as in Example 1.

[0034] Example 5

[0035] 0.12 g KNO3 was used to replace 0.06 g KNO3 in Example 1, and the other steps were the same as those in Example 1.

[0036] Example 6

[0037] Weigh 0.5 g of the catalyst and 16 g of isobutylaldehyde and react directly at 60° C. for 4 h. The reaction is carried out in a three-necked flask equipped with a thermometer and a condensation reflux device, heated in a water bath, and stirred magnetically. Finally, the reaction product is taken out and analyzed by gas chromatography.

[0038] The steps for preparing the catalyst are the same as those in Example 1.

[0039] Comparative Example 1

[0040] Preparation of catalyst: First, determine the water absorption rate of SBA-15, then accurately weigh 1g of SBA-15, dry it at 100℃ and use it as a carrier; then weigh 0.18gBa(NO3)2, 0.06gKNO3 and 0.16g[(NH4)6Mo7O 24] was dissolved in 10 ml of deionized water to obtain a solution. The solution was allowed to stand for half an hour, and then the prepared SBA-15 was dripped in drop by drop to perform equal volume impregnation, and then sealed and placed at room temperature for 6 hours, and then moved into a 100°C oven for drying. 0.12 g of NaOH was dissolved in 5 ml of deionized water to obtain a solution, and then the above-treated catalyst precursor was dripped in drop by drop to perform equal volume impregnation, and then sealed and placed at room temperature for 3 hours, and then moved into a 100°C oven for 5 hours for drying to obtain a catalyst precursor. The impregnated product was dried and calcined at 550°C for 6 hours.

[0041] The other steps are the same as in Example 1.

[0042] Comparative Example 2

[0043] Preparation of catalyst: First, determine the water absorption rate of SBA-15, then accurately weigh 1g of SBA-15, dry it at 100℃ and use it as a carrier; then weigh 0.11gCa(NO3)2, 0.06gKNO3 and 0.16g[(NH4)6Mo7O 24 ] was dissolved in 10 ml of deionized water to obtain a solution. The solution was allowed to stand for half an hour, and then the prepared SBA-15 was added dropwise to impregnate the solution with equal volumes. The solution was then sealed and placed at room temperature for 12 hours, and then moved to a 100°C oven for drying to obtain a catalyst precursor. The impregnated product was dried and calcined at 550°C for 6 hours.

[0044] The other steps are the same as in Example 1.

[0045] Comparative Example 3

[0046] Preparation of catalyst: First, determine the water absorption rate of SBA-15, then accurately weigh 1g SBA-15, dry it at 100℃ and use it as a carrier; then weigh 0.11g Ca(NO3)2, 0.18g Ba(NO3)2 and 0.16g [(NH4)6Mo7O 24 ] was dissolved in 10 ml of deionized water to obtain a solution. The solution was allowed to stand for half an hour, and then the prepared SBA-15 was dripped in drop by drop to perform equal volume impregnation, and then sealed and placed at room temperature for 12 hours, and then moved into a 100°C oven for drying. 0.12 g of NaOH was dissolved in 5 ml of deionized water to obtain a solution, and then the above-treated catalyst precursor was dripped in drop by drop to perform equal volume impregnation, and then sealed and placed at room temperature for 3 hours, and then moved into a 100°C oven for 5 hours for drying to obtain a catalyst precursor. The impregnated product was dried and calcined at 550°C for 6 hours.

[0047] The other steps are the same as in Example 1.

[0048] Comparative Example 4

[0049] Preparation of catalyst: First, determine the water absorption rate of SBA-15, then accurately weigh 1g SBA-15, dry it at 100℃ and use it as a carrier; then weigh 0.11g Ca(NO3)2, 0.18g Ba(NO3)2, 0.06g KNO3 and 0.16g [(NH4)6Mo7O 24 ] was dissolved in 10 ml of deionized water to obtain a solution. The solution was allowed to stand for half an hour, and then the prepared SBA-15 was added dropwise to impregnate the solution with equal volumes, and then the solution was sealed and placed at room temperature for 12 hours, and then moved to a 100°C oven for drying. The impregnated product was dried and calcined at 550°C for 6 hours.

[0050] The other steps are the same as in Example 1.

[0051] Comparative Example 5

[0052] Preparation of catalyst: SBA-15 loaded CaO / BaO / K2O mesoporous catalyst was prepared by impregnation method. First, the water absorption rate of SBA-15 was determined, and then 1g SBA-15 was accurately weighed and dried at 100℃ for use as a carrier; then 0.11g Ca(NO3)2, 0.18g Ba(NO3)2 and 0.06g KNO3 were weighed and dissolved in 10ml deionized water to obtain a solution. The solution was allowed to stand for half an hour, and then dripped into the prepared SBA-15 drop by drop for equal volume impregnation, and then sealed and placed at room temperature for 12h, and then moved to a 100℃ oven for drying. 0.12g NaOH was dissolved in 5ml deionized water to obtain a solution, and then dripped into the above-treated catalyst precursor drop by drop for equal volume impregnation, and then sealed and placed at room temperature for 3h, and then moved to a 100℃ oven for 5h for drying to obtain a catalyst precursor. The impregnated product was dried and calcined at 550℃ for 6h. A double basic center catalyst with a catalyst active component mass fraction of 20% is obtained.

[0053] The other steps are the same as in Example 1.

[0054] Table 1 Comparison of product performance between examples and comparative examples

[0055] Serial number Raw material conversion rate (%) Primary alcohol ester selectivity (%) Example 1 98 70 Example 2 99 65 Example 3 98 61 Example 4 99 62 Example 5 98 68 Example 6 97 64 Comparative Example 1 69 40 Comparative Example 2 70 50 Comparative Example 3 66 54 Comparative Example 4 68 63 Comparative Example 5 73 60

[0056] Table 1 shows that the solid base catalyst loaded by the method has a high reaction activity to the raw materials, the solid product is easy to separate when the catalyst is used, and the equipment is not damaged. It is an environmentally friendly green catalyst.

[0057] It should be understood that those skilled in the art can make improvements and changes based on the above description, and these improvements and changes should all fall within the scope of protection of the claims of the present invention.

Claims

1. A solid base catalyst for catalytic synthesis of alcohol ester containing high primary ester, characterized in that: The solid base catalyst is supported by SBA-15, with CaO, BaO and K2O as catalyst active centers and MoO3 acting synergistically; a SBA-15 supported CaO / BaO / K2O-MoO3 catalyst is prepared for catalytic synthesis of alcohol ester twelve containing high primary ester; The preparation method of the SBA-15 loaded CaO / BaO / K2O-MoO3 catalyst is as follows: (1) Take Ca(NO3)2, Ba(NO3)2, KNO3 and (NH4)6Mo7O 24 Solution A is prepared; then NaOH is dissolved in deionized water to prepare solution B; the Ca(NO3)2, Ba(NO3)2, KNO3 and (NH4)6Mo7O in step (1) are 24 The molar ratio of calcium, barium and potassium is n(Ca):n(Ba):n(K)=1:1:1~1:10:10, the molar ratio of calcium and molybdenum is n(Ca):n(Mo)=1:1~1:10; the molar ratio of Ca(NO3)2 and NaOH is n(Ca):n(Na)=1:1~1:0.1; (2) Taking the carrier SBA-15 and performing purification and drying treatment; (3) dripping solution A in step (1) into the carrier in step (2) dropwise, leaving it to stand for 12 hours, then dripping solution B into the carrier loaded with active components, leaving it to stand for 3 hours; (4) placing the solid obtained in step (3) into an oven for drying to obtain a catalyst precursor; (5) calcining the catalyst precursor obtained in step (4) to obtain an SBA-15-loaded CaO / BaO / K2O-MoO3 catalyst; The reaction steps for catalytic synthesis of primary alcohol ester twelve are as follows: using isobutyraldehyde as raw material, firstly carrying out aldol condensation reaction at low temperature of 20-40°C for 2-3 hours under the condition of SBA-15 loaded with CaO / BaO / K2O-MoO3 catalyst, then raising the temperature to 40-90°C for Cannizzaro reaction for 2-10 hours to obtain alcohol ester twelve containing high primary ester.

2. The use according to claim 1, characterized in that: The drying conditions in step (2) and step (4) are drying in a drying oven at 100-140° C. for 5-12 hours.

3. The use according to claim 1, characterized in that: The calcination conditions in step (5) are calcination at 500-700° C. for 5-8 hours.

4. The use according to claim 1, characterized in that: The active components of CaO / BaO / K2O-MoO3 in SBA-15 loaded CaO / BaO / K2O-MoO3 catalyst account for 1%~50% of the carrier mass fraction.

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