Synthesis method of chloride-free cationic etherifying agent

Abstract

The invention discloses a synthesis method of a chloride-free cationic etherifying agent, and belongs to the technical field of cationic etherifying agents, and the method comprises the following steps: adding methyldiethanolamine and a catalyst into a reaction kettle, controlling the temperature at 15-25 DEG C, then adding acid, and keeping the temperature at 15-25 DEG C for 2-4 hours; dropwise adding epoxypropane, and reacting at 30 DEG C for 5-10 hours to obtain a cationic etherifying agent crude product; wherein the catalyst is a mesoporous silica supported phosphotungstic acid catalyst and is prepared by the following steps: dissolving phosphotungstic acid and barium nitrate in absolute ethyl alcohol, mixing and reacting with an absolute ethyl alcohol solution containing cetyltrimethylammonium bromide, then adding tetraethoxysilane and cyclohexane, standing, carrying out suction filtration, drying and calcining to obtain the mesoporous silica supported phosphotungstic acid catalyst. The prepared catalyst has excellent catalytic activity and stability, can significantly improve the reaction conversion rate and selectivity, effectively inhibits side reactions, and can be repeatedly used. The finally obtained cationic etherifying agent is high in purity, does not contain chloride ions, and meets the requirements of green chemical industry.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cationic etherifying agents, and particularly relates to a synthesis method of a chlorine-free cationic etherifying agent. BACKGROUND

[0002] Cationic etherifying agents are an important class of chemical modifiers, mainly used for cationic functional modification of natural or synthetic polymer materials (such as cellulose, starch, polyacrylamide, etc.). Its core function is to introduce cationic groups (such as quaternary ammonium salt groups) into the polymer chain through etherification reaction, giving the material positive charge characteristics, thereby significantly improving its adsorption, water solubility, antibacterial property and binding capacity with negatively charged substances. Since the 1970s, cationic etherifying agents have been widely used in many industrial fields such as papermaking, daily chemical industry, oil exploitation, water treatment, etc.

[0003] At present, the product is mainly used as an etherifying agent for cationic starch, cationic polysaccharide and modified guar gum, etc., for preparing cationic starch, cationic polyacrylamide, electroplating additives, textile printing and dyeing auxiliaries, antistatic agents, papermaking auxiliaries, cationic surfactants, water treatment flocculants, etc. However, with the advancement of carbon neutralization target, the market demand for efficient, low-carbon and multifunctional cationic etherifying agents is increasing. The cationic etherifying agents used in the prior art are mostly prepared from chlorine-containing compounds (such as CN118847168B, CN11895916B, CN119192427B), although the related preparation process is relatively mature, but the product itself inevitably contains chloride ions, which not only leads to poor environmental friendliness in the subsequent application process, is not friendly to the health and safety of operators, and also seriously limits the expansion of the application range of cationic etherifying agents. SUMMARY

[0004] In order to overcome the above technical problems existing in the prior art, the present application provides a synthesis method of a chlorine-free cationic etherifying agent. The present application uses a composite material of ionic liquid supported silica doped with Ba as a catalyst, which significantly improves the reaction rate and selectivity. The catalyst can effectively improve the conversion rate of the reactants, reduce the content of residual propylene oxide, and effectively inhibit the occurrence of side reactions, thereby improving the selectivity of the cationic etherifying agent product. In addition, the catalyst also has excellent stability and can be repeatedly used for industrial production, significantly reducing the production cost.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] In one aspect, the present application provides a synthesis method of a chlorine-free cationic etherifying agent, comprising the following steps:

[0007] (1) methyl diethanol amine and catalyst are added into a reaction kettle, temperature is controlled at 15-25 DEG C, then acid is added, and it is kept at 15-25 DEG C for 2-4 hours;

[0008] (2) propylene oxide is added dropwise into the system of step (1), and it is reacted at 30 DEG C for 5-10 hours to obtain a cation etherification agent crude product;

[0009] The catalyst is a mesoporous silica supported phosphotungstic acid catalyst, and the catalyst is prepared by a method comprising the following steps: phosphotungstic acid and barium nitrate are dissolved in anhydrous ethanol, mixed and reacted with a solution of cetyltrimethylammonium bromide in anhydrous ethanol, then ethyl orthosilicate and cyclohexane are added, and after standing, suction filtration, drying and calcination, the catalyst is obtained.

[0010] As a further scheme of the application: in step (1), the mass ratio of the methyl diethanol amine to the catalyst is 100:2-5;

[0011] And / or, in step (1), the molar ratio of the methyl diethanol amine to the acid is 1:0.5-1.1;

[0012] And / or, in step (1), the acid is any one of acetic acid, methylbenzenesulfonic acid, sulfuric acid, methanesulfonic acid and citric acid.

[0013] As a further scheme of the application: in step (2), the molar ratio of the methyl diethanol amine to propylene oxide is 1:1-1.5.

[0014] As a further scheme of the application: the preparation method of the catalyst specifically comprises the following steps:

[0015] S1, phosphotungstic acid and barium nitrate are dissolved in anhydrous ethanol to obtain solution A;

[0016] S2, cetyltrimethylammonium bromide is dissolved in anhydrous ethanol to obtain solution B;

[0017] S3, the solution A is added dropwise to the solution B while stirring to react;

[0018] S4, ethyl orthosilicate and cyclohexane are added to the reaction solution of S3 to react;

[0019] S5, the mixture obtained in S4 is allowed to stand, suction filtered, the filter residue is dried and calcined to obtain the catalyst.

[0020] As a further scheme of the application: in step S1, the mass ratio of the phosphotungstic acid to the barium nitrate is 2-2.5:1, and the addition ratio of the phosphotungstic acid to the anhydrous ethanol is 2g:5mL;

[0021] And / or, in step S2, the addition ratio of hexadecyltrimethylammonium bromide and anhydrous ethanol is 1g:10-15mL;

[0022] And / or, in step S2, the mass ratio of phosphotungstic acid to hexadecyltrimethylammonium bromide is 4 to 5:1;

[0023] And / or, in step S3, the reaction is carried out at 50–75°C for 1–3 hours;

[0024] And / or, in step S4, the volume ratio of the tetraethyl orthosilicate to cyclohexane is 28-30:1;

[0025] And / or, in step S4, the addition ratio of phosphotungstic acid and tetraethyl orthosilicate is 1g:5mL;

[0026] And / or, in step S4, the reaction time is 0.5 to 1 hour;

[0027] And / or, in step S5, the settling time is 3 to 4 hours;

[0028] And / or, in step S5, the drying is carried out at 100-120°C for 1-3 hours;

[0029] And / or, in step S5, the calcination is carried out at 400-700°C for 2-4 hours.

[0030] As a further aspect of the present invention: after step (2), the method further includes:

[0031] The crude cationic etherifying agent was concentrated by vacuum distillation to obtain the cationic etherifying agent.

[0032] The beneficial effects of this invention are as follows:

[0033] (1) This invention uses phosphotungstic acid and hexadecyltrimethylammonium bromide (CTAB) as precursors, modifies them by doping with barium (Ba) metal ions, and loads them onto a microporous silica support. A silica-supported phosphotungstic acid (HPMo / SiO2) catalyst with a mesoporous structure is prepared by hydrothermal method. In this design, silica, as a porous template, has a high specific surface area, providing abundant edge structures for the catalytic reaction, thus significantly enhancing the contact efficiency of the reactants; at the same time, its stable porous structure effectively improves the overall stability of the catalyst. Ba, as a transition metal component, has good catalytic activity and works synergistically with phosphotungstic acid, not only improving the conversion rate of the main reaction but also effectively suppressing the occurrence of side reactions.

[0034] (2) This invention uses tetraethyl orthosilicate as a silicon source to achieve Ba doping, which can introduce more active sites on the Ba surface and greatly improve the dispersion of active metals, effectively suppressing their agglomeration during the reaction process. In addition, this method can also enhance the stability of the catalyst structure, making the active metal components less prone to stripping and loss, thereby giving the catalyst excellent recycling performance, enabling it to be used repeatedly in industrial production, and significantly reducing production costs. Detailed Implementation

[0035] The present invention is further illustrated below by way of examples, but these examples do not limit the invention to the scope of the embodiments described. Experimental methods in the following examples, unless otherwise specified, were performed according to conventional methods and conditions, or as selected in the product instructions. Furthermore, all reagents and raw materials used in this invention are commercially available.

[0036] Example 1

[0037] A method for synthesizing a chlorine-free cationic etherifying agent, specifically including the following steps:

[0038] (1) Dissolve 19.9g of phosphotungstic acid and 8.60g (20% loading) of barium nitrate in 50mL of anhydrous ethanol solution and label it as solution A. Place 4.45g of hexadecyltrimethylammonium bromide in a reaction vessel and dissolve it in 50mL of anhydrous ethanol in the same way and label it as solution B.

[0039] (2) Add solution A dropwise to solution B while stirring. Stir the two solutions A and B at 65°C for 1.5 h. Then add 100 mL of tetraethyl orthosilicate and 3.3 mL of cyclohexane and continue the reaction for 0.5 h.

[0040] (3) Let stand at room temperature for 4 hours, filter, dry the filter residue at 110℃ for 2 hours, and finally calcine the product in a muffle furnace at 600℃ for 3 hours to obtain the catalyst.

[0041] (4) Add 119.16g of methyldiethanolamine and 5g of catalyst to the reactor, turn on the cooling equipment, and control the temperature at 20-25℃. Then add 50% sulfuric acid (the molar ratio of methyldiethanolamine to sulfuric acid is 1:0.5) dropwise, keep the temperature at 20-25℃ for 4h, and then add propylene oxide (the molar ratio of methyldiethanolamine to propylene oxide is 1:1). Keep the temperature at 30℃ for 8h to obtain the crude cationic etherifying agent. After further vacuum distillation and concentration, the cationic etherifying agent is obtained.

[0042] Example 2

[0043] A method for synthesizing a chlorine-free cationic etherifying agent, specifically including the following steps:

[0044] (1) Dissolve 59.7g of phosphotungstic acid and 26.0g (20% loading) of barium nitrate in 150mL of anhydrous ethanol solution and label it as solution A. Place 13.36g of hexadecyltrimethylammonium bromide in a reaction vessel and dissolve it in 150mL of anhydrous ethanol in the same way and label it as solution B.

[0045] (2) Add solution A dropwise to solution B while stirring. Stir the two solutions A and B at 60°C for 1.5 h. Then add 300 mL of tetraethyl orthosilicate and 10 mL of cyclohexane and continue the reaction for 0.5 h.

[0046] (3) Let stand at room temperature for 4 hours, filter, dry the filter residue at 110℃ for 2 hours, and finally calcine the product in a muffle furnace at 600℃ for 3 hours to obtain the catalyst.

[0047] (4) Add 200g of methyldiethanolamine and 6g of catalyst to the reactor, turn on the cooling equipment and control the temperature at 20-25℃, then add acetic acid dropwise (the molar ratio of methyldiethanolamine and acetic acid is 1:1), keep the temperature at 20-25℃ for 4h, then add propylene oxide dropwise (the molar ratio of methyldiethanolamine and propylene oxide is 1:1.05), keep the temperature at 30℃ for 6h, and obtain the crude cationic etherifying agent. After further vacuum distillation and concentration, the cationic etherifying agent is obtained.

[0048] Example 3

[0049] A method for synthesizing a chlorine-free cationic etherifying agent, specifically including the following steps:

[0050] (1) Dissolve 50g of phosphotungstic acid and 21.77g (20% loading) of barium nitrate in 125.5mL of anhydrous ethanol solution and label it as solution A. Place 11.18g of hexadecyltrimethylammonium bromide in a reaction vessel and dissolve it in 125.5mL of anhydrous ethanol in the same way and label it as solution B.

[0051] (2) Add solution A dropwise to solution B while stirring. Stir the two solutions A and B at 70°C for 2 hours. Then add 250 mL of tetraethyl orthosilicate and 8.5 mL of cyclohexane and continue the reaction for 0.5 hours.

[0052] (3) Let stand at room temperature for 4 hours, filter, dry the filter residue at 110℃ for 2 hours, and finally calcine the product in a muffle furnace at 600℃ for 3 hours to obtain the catalyst.

[0053] (4) Add 130g of methyldiethanolamine and 3.5g of catalyst to the reactor, turn on the cooling equipment and control the temperature at 20-25℃, then add methanesulfonic acid dropwise (the molar ratio of methyldiethanolamine to methanesulfonic acid is 1:1.05), keep the temperature at 20-25℃ for 4h, then add propylene oxide dropwise (the molar ratio of methyldiethanolamine to propylene oxide is 1:1.1), keep the temperature at 30℃ for 7h, and obtain the crude cationic etherifying agent. After further vacuum distillation and concentration, the cationic etherifying agent is obtained.

[0054] Example 4

[0055] A method for synthesizing a chlorine-free cationic etherifying agent, specifically including the following steps:

[0056] (1) Dissolve 59.7g of phosphotungstic acid and 26.0g (20% loading) of barium nitrate in 150mL of anhydrous ethanol solution and label it as solution A. Place 13.36g of hexadecyltrimethylammonium bromide in a reaction vessel and dissolve it in 150mL of anhydrous ethanol in the same way and label it as solution B.

[0057] (2) Add solution A dropwise to solution B while stirring. Stir the two solutions A and B at 75°C for 1.5 h. Then add 300 mL of tetraethyl orthosilicate and 10 mL of cyclohexane and continue the reaction for 0.5 h.

[0058] (3) Let stand at room temperature for 4 hours, filter, dry the filter residue at 115℃ for 2 hours, and finally calcine the product in a muffle furnace at 550℃ for 3 hours to obtain the catalyst.

[0059] (4) Add 110g of methyldiethanolamine and 4g of catalyst to the reactor, turn on the cooling equipment, and control the temperature at 15-20℃. Then add p-toluenesulfonic acid dropwise (the molar ratio of methyldiethanolamine to p-toluenesulfonic acid is 1:1.05), keep the temperature at 15-20℃ for 4h, and then add propylene oxide dropwise (the molar ratio of methyldiethanolamine to propylene oxide is 1:1.15). Keep the temperature at 30℃ for 5h to obtain the crude cationic etherifying agent. After further vacuum distillation and concentration, the cationic etherifying agent is obtained.

[0060] Comparative Example 1

[0061] A method for synthesizing a cationic etherifying agent, specifically including the following steps:

[0062] (1) Dissolve 59.7g of phosphotungstic acid and 26.0g (20% loading) of barium nitrate in 150mL of anhydrous ethanol solution and label it as solution A. Place 10.57g of sodium dodecyl sulfate in a reaction vessel and dissolve it in 150mL of anhydrous ethanol in the same way and label it as solution B.

[0063] (2) Add solution A dropwise to solution B while stirring. Stir the two solutions A and B at 70°C for 2 hours. Then add 300 mL of tetraethyl orthosilicate and 10 mL of cyclohexane and continue the reaction for 0.5 hours.

[0064] (3) Let stand at room temperature for 4 hours, filter, dry the filter residue at 110°C for 2 hours, and finally calcine the product in a muffle furnace at 300°C for 3 hours to obtain the catalyst.

[0065] (4) Add 130g of methyldiethanolamine and 5g of catalyst to the reactor, turn on the cooling equipment and control the temperature at 15-25℃, then add acetic acid dropwise (the molar ratio of methyldiethanolamine to acetic acid is 1:1.01), keep the temperature at 15-25℃ for 4h, then add propylene oxide dropwise (the molar ratio of methyldiethanolamine to propylene oxide is 1:1.05), keep the temperature at 30℃ for 8h, and obtain the crude cationic etherifying agent. After further vacuum distillation and concentration, the cationic etherifying agent is obtained.

[0066] Comparative Example 2

[0067] A method for synthesizing a cationic etherifying agent, specifically including the following steps:

[0068] (1) Dissolve 59.7g of phosphotungstic acid and 26.0g (20% loading) of barium nitrate in 150mL of anhydrous ethanol solution and label it as solution A. Place 13.36g of hexadecyltrimethylammonium bromide in a reaction vessel and dissolve it in 150mL of anhydrous ethanol in the same way and label it as solution B.

[0069] (2) Add solution A dropwise to solution B while stirring. Stir the two solutions A and B at 40°C for 1.5 h. Then add 10 g of carbon nanotubes and 10 mL of cyclohexane and continue the reaction for 0.5 h.

[0070] (3) Let stand at room temperature for 4 hours, filter, dry the filter residue at 80°C for 2 hours, and finally calcine the product in a tube furnace at 300°C for 3 hours to obtain the catalyst.

[0071] (4) Add 150g of methyldiethanolamine and 5g of catalyst to the reactor, turn on the cooling equipment, and control the temperature at 20-25℃. Then add 50% sulfuric acid (the molar ratio of methyldiethanolamine to sulfuric acid is 1:0.5) dropwise, keep the temperature at 20-25℃ for 4h, and then add propylene oxide (the molar ratio of methyldiethanolamine to propylene oxide is 1:1.2). Keep the temperature at 30℃ for 7h to obtain the crude cationic etherifying agent. After further vacuum distillation and concentration, the cationic etherifying agent is obtained.

[0072] Comparative Example 3

[0073] The only difference from Example 1 is that barium nitrate was not added in step (1).

[0074] Comparative Example 4

[0075] The only difference from Example 1 is that in step (1), hexadecyltrimethylammonium bromide is replaced with sodium dodecyl sulfate in equimolar amounts.

[0076] Comparative Example 5

[0077] The only difference from Example 1 is that in step (2), the reaction temperature for mixing solutions A and B is 40°C.

[0078] Comparative Example 6

[0079] The only difference from Example 1 is that in step (4), the reaction temperature after adding propylene oxide is 50°C.

[0080] Effect Examples

[0081] The purity of samples from Examples 1-4 and Comparative Examples 1-6 was tested: Following the chemical titration method (GB / T27816-2011), acid-base neutralization titration was performed, and the endpoint was determined using an indicator. The content of cationic etherifying agent in the product was then detected. The test results are shown in Tables 1 and 2.

[0082] Table 1

[0083]

[0084]

[0085] As can be seen from Table 1, the yield of the product using the synthesis method provided by this invention is above 97%. This indicates that the addition of the supported ionic liquid catalyst can reduce side reactions and improve reaction selectivity, thereby effectively improving the quality of the cationic etherifying agent.

[0086] Table 2 shows the changes in product (mass percentage, %) after the catalysts prepared in Examples 1-4 and Comparative Examples 1-6 were used continuously for a period of time.

[0087] Table 2

[0088] Samples 60h 120h 180h 240h 300h 360h Example 1 98.35 98.12 98.08 98.02 97.18 96.55 Example 2 97.27 96.93 96.87 96.58 96.24 95.86 Example 3 98.28 98.14 98.06 97.88 97.16 96.72 Example 4 98.22 98.17 98.04 97.97 97.83 96.95 Comparative Example 1 83.64 80.67 76.89 74.54 68.38 65.19 Comparative Example 2 85.91 82.34 75.42 73.18 66.79 64.93 Comparative Example 3 91.05 89.53 85.61 81.72 75.84 69.95 Comparative Example 4 88.74 86.27 83.39 80.51 77.63 72.22 Comparative Example 5 92.39 90.87 87.32 83.51 78.73 70.94 Comparative Example 6 90.57 90.03 86.41 81.62 76.83 70.71

[0089] As shown in Table 2, after the catalysts in Examples 1 to 4 were run continuously for 300 hours, the selectivity did not decrease significantly. Example 4 showed the best stability, with the catalyst performance decreasing by only 1.28% after 360 hours of continuous operation. This demonstrates that the catalyst prepared in this process has excellent stability and can be repeatedly used in the industrial production of cationic etherifying agents, thereby effectively reducing costs.

[0090] Finally, it should be noted that in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0091] Although this disclosure has been described above through specific embodiments, it should be understood that those skilled in the art can devise various modifications, improvements, or equivalents to this disclosure within the spirit and scope of the appended solutions. Such modifications, improvements, or equivalents should also be considered to be included within the scope of protection claimed in this disclosure.

Claims

1. A method for synthesizing a chloride-free cationic etherifying agent, characterized in that, Includes the following steps: (1) Add methyldiethanolamine and catalyst to the reaction vessel, control the temperature at 15-25℃, then add acid, and keep warm at 15-25℃ for 2-4 hours; (2) Add propylene oxide dropwise to the system of step (1) and react at 30°C for 5 to 10 hours to obtain crude cationic etherifying agent; The catalyst is a mesoporous silica-supported phosphotungstic acid catalyst, which is prepared by a method including the following steps: dissolving phosphotungstic acid and barium nitrate in anhydrous ethanol, mixing and reacting with an anhydrous ethanol solution containing hexadecyltrimethylammonium bromide, then adding tetraethyl orthosilicate and cyclohexane, and obtaining the catalyst after standing, filtration, drying and calcination.

2. The method for synthesizing the chloride-free cationic etherifying agent according to claim 1, characterized in that, In step (1), the mass ratio of the methyldiethanolamine to the catalyst is 100:2 to 5; And / or, in step (1), the molar ratio of the methyldiethanolamine to the acid is 1:0.5 to 1.1; And / or, in step (1), the acid is any one of acetic acid, methylbenzenesulfonic acid, sulfuric acid, methanesulfonic acid and citric acid.

3. The method for synthesizing the chloride-free cationic etherifying agent according to claim 1, characterized in that, In step (2), the molar ratio of methyldiethanolamine to propylene oxide is 1:1 to 1.

5.

4. The method for synthesizing the chloride-free cationic etherifying agent according to claim 1, characterized in that, The preparation method of the catalyst specifically includes the following steps: S1. Dissolve phosphotungstic acid and barium nitrate in anhydrous ethanol to obtain solution A; S2. Dissolve hexadecyltrimethylammonium bromide in anhydrous ethanol to obtain solution B; S3. While stirring, add solution A dropwise to solution B to carry out the reaction; S4. Add tetraethyl orthosilicate and cyclohexane to the reaction solution of S3 to carry out the reaction; S5. The mixture obtained in S4 is allowed to stand, filtered, the filter residue is dried, and calcined to obtain the catalyst.

5. The method for synthesizing the chlorine-free cationic etherifying agent according to claim 4, characterized in that, In step S1, the mass ratio of phosphotungstic acid to barium nitrate is 2-2.5:1, and the addition ratio of phosphotungstic acid to anhydrous ethanol is 2g:5mL. And / or, in step S2, the addition ratio of hexadecyltrimethylammonium bromide and anhydrous ethanol is 1g:10-15mL; And / or, in step S2, the mass ratio of phosphotungstic acid to hexadecyltrimethylammonium bromide is 4 to 5:1; And / or, in step S3, the reaction is carried out at 50–75°C for 1–3 hours; And / or, in step S4, the volume ratio of the tetraethyl orthosilicate to cyclohexane is 28-30:1; And / or, in step S4, the addition ratio of phosphotungstic acid and tetraethyl orthosilicate is 1g:5mL; And / or, in step S4, the reaction time is 0.5 to 1 hour; And / or, in step S5, the settling time is 3 to 4 hours; And / or, in step S5, the drying is carried out at 100-120°C for 1-3 hours; And / or, in step S5, the calcination is carried out at 400-700°C for 2-4 hours.

6. The method for synthesizing the chloride-free cationic etherifying agent according to claim 1, characterized in that, Following step (2), the method further includes: The crude cationic etherifying agent was concentrated by vacuum distillation to obtain the cationic etherifying agent.

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