Transesterification process
By spraying azeotrope into the reactor during the transesterification reaction to remove byproduct alcohol, the problem of low efficiency of byproduct removal in the transesterification reaction is solved, and higher reaction efficiency and yield are achieved, and raw material and energy consumption are reduced.
Patent Information
- Application Number
- CN202510322261.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-20
AI Technical Summary
In transesterification reaction, the removal efficiency of by-product small molecule alcohols is low, resulting in limited reaction rate. It is necessary to increase the proportion of raw materials and use azeotropic methods, resulting in increased raw material loss and energy consumption.
During the transesterification reaction, the azeotropic agent is sprayed into the reactor, and the azeotropic agent and the by-product alcohol are azeotropic, and the evaporation is carried out using a low-boiling azeotropic mixture to reduce raw material and energy consumption.
It significantly improves the removal efficiency of by-product alcohol, reduces the consumption of raw materials and energy, achieves higher product conversion rate and higher product purity, and reduces the energy consumption of subsequent purification steps.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a transesterification process. Background Art
[0002] Transesterification is an important chemical reaction. It involves mixing one ester with another fatty acid, alcohol, itself, or other esters, accompanied by carboxyl exchange or molecular rearrangement to form new esters. This reaction can change the fatty acid and glyceride composition and structure of oils and fats, thereby altering the properties of oils and fats, and is one of the important means for oil modification in the oil industry. Especially in the process of preparing biodiesel, transesterification refers to the transesterification of triglycerides in animal and vegetable oils and microbial oils with lower alcohols (such as methanol) under the action of a catalyst. This process can change the properties of oils and fats without changing the fatty acid composition, and is also called alcoholysis reaction.
[0003] In transesterification, the reaction between esters and alcohols usually involves the replacement of macromolecular alcohols to generate small molecular alcohols and new esters. Since the small molecular alcohols generated during the reaction can be removed by distillation and other methods, this helps to drive the reaction in the forward direction. However, transesterification is essentially a reversible reaction, and its reaction rate is affected by the removal rate of the by-product small molecular alcohols. According to the principle of chemical equilibrium, when the concentration of the by-product small molecular alcohols decreases, the reaction tends to generate more product esters, that is, the reaction proceeds in the forward direction.
[0004] To accelerate the removal of by-products and promote the reaction, the commonly used method at present is to increase the raw material ratio and use the azeotropic method to remove the by-product small molecular alcohols from the reaction system. Small molecular alcohols often form an azeotrope with the raw materials or are entrained and distilled out with the raw materials, resulting in a relatively high reaction temperature. This method not only causes loss of raw materials, but also may trigger additional side reactions, and then the excess raw materials need to be recovered, purified and reused, increasing the energy consumption and cost.
[0005] To solve the above problems, the applicant has developed a transesterification process. Summary of the Invention
[0006] The object of the present invention is to provide a transesterification process to solve the technical problems mentioned in the above background art.
[0007] The technical solution for achieving the object of the present invention is:
[0008] The present invention provides a transesterification process. The transesterification reaction is a reaction in which a raw material ester and a raw material alcohol react under the action of a catalyst to produce a product ester and a by-product alcohol, and it includes the following process steps: adding the raw material ester, the raw material alcohol, and the catalyst into a reactor, reacting at a reaction temperature to obtain a reaction product; spraying an azeotropic agent into the reactor during the reaction process, and the azeotropic agent and the by-product alcohol are azeotropically evaporated at the reaction temperature to remove the by-product alcohol; the low-boiling azeotropic mixture formed by mixing the azeotropic agent and the by-product alcohol is used for evaporation, thereby effectively removing the by-product alcohol; spraying the azeotropic agent not only ensures that the azeotropic agent can fully contact the materials in the reactor, but also gives the azeotropic agent an initial driving force, enabling it to quickly and fully combine with the by-product alcohol and evaporate together. Compared with the traditional method of promoting the reaction in the positive direction by increasing the raw material ratio, this process significantly reduces the consumption of raw materials and energy, and at the same time improves the removal efficiency of the by-product alcohol, and can achieve a higher product conversion rate within a shorter reaction time.
[0009] Further, the molar ratio of the raw material ester to the raw material alcohol is 1.2 - 1.5:1; the mass of the catalyst is 1 - 5% of the mass of the raw material alcohol.
[0010] Further, the catalyst uses an organotin catalyst.
[0011] Further, the raw material ester is an unsaturated ester, and the general formula is:
[0012]
[0013] Among them, R1 is -H, -CH3; R2 is -CH3, -CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3.
[0014] Further, the reaction temperature is 95 - 130 °C, and the materials in the reaction system can maintain a boiling state at this reaction temperature.
[0015] Further, the azeotropic agent uses any one of straight-chain alkanes with 5 to 7 carbon atoms, or any one of cycloalkanes with 5 to 7 carbon atoms.
[0016] Further, if the raw material ester is a methyl ester, then the by-product alcohol is methanol, and the azeotropic agent includes cyclopentane, n-hexane, n-heptane, cyclohexane; among them, when the azeotropic agent is n-pentane, the mass ratio of n-pentane to methanol is 91:9; when the azeotropic agent is n-hexane, the mass ratio of n-hexane to methanol is 72:28; when the azeotropic agent is n-heptane, the mass ratio of n-heptane to methanol is 48.5:51.5; when the azeotropic agent is cyclohexane, the mass ratio to methanol is 62.8:37.2.
[0017] Further, when the raw material ester is ethyl ester, the by-product alcohol is ethanol, and the azeotropic agent includes cyclopentane, n-hexane, n-heptane, and n-octane; wherein, when the azeotropic agent is n-pentane, the mass ratio of n-pentane to ethanol is 95:1; when the azeotropic agent is n-hexane, the mass ratio of n-hexane to ethanol is 79:21; when the azeotropic agent is n-heptane, the mass ratio of n-heptane to ethanol is 51:49; when the azeotropic agent is n-octane, the mass ratio of n-octane to ethanol is 22:78.
[0018] Further, before being sprayed into the reactor, the azeotropic agent needs to be preheated to a first temperature, which is not lower than the boiling point of the azeotropic agent and not higher than the reaction temperature.
[0019] Further, the spraying pressure is 0.15 - 0.4 MPa.
[0020] Further, the azeotropic agent is sprayed into the reactor from the bottom.
[0021] Further, an inhibitor needs to be added to the system, and the dosage of the inhibitor is 0.05% - 0.15% of the total mass of the unsaturated raw material ester.
[0022] Adopting the above technical solutions, the present invention has the following beneficial effects:
[0023] (1) During the transesterification reaction process of the present invention, an azeotropic agent is sprayed into the reactor, and the low-boiling azeotropic mixture formed by the azeotropic agent and the by-product alcohol is used for evaporation, thereby effectively removing the by-product alcohol; spraying the azeotropic agent not only ensures that the azeotropic agent can fully contact the materials in the reactor, but also gives the azeotropic agent initial power, enabling it to quickly combine with the by-product alcohol and evaporate together. Compared with the traditional method of promoting the reaction in the forward direction by increasing the raw material ratio, this process significantly reduces the consumption of raw materials and energy, while improving the removal efficiency of the by-product alcohol, achieving a higher yield within a shorter reaction time, and the prepared reaction product has a high purity without subsequent purification treatment, reducing the energy consumption in the purification step and having good economic benefits.
[0024] (2) Before being sprayed into the reactor, the azeotropic agent of the present invention is preheated to the first temperature to ensure that it does not affect the reaction temperature of the reaction materials in the reactor due to the normal temperature state, thereby maintaining the temperature stability of the reaction system and avoiding the decrease in reaction efficiency and product yield caused by temperature fluctuations; it can also ensure that once the azeotropic agent enters the reaction environment, it can quickly play its role, minimizing the existence time of the by-product alcohol, and thus promoting the reaction to proceed efficiently in the forward direction, not only improving the reaction rate and selectivity, but also further enhancing the stability and reliability of the entire transesterification process.
[0025] (3) The azeotropic agent of the present invention is sprayed into the reactor from the bottom to ensure sufficient contact between the azeotropic agent and the materials in the reactor, and thus sufficient contact with the by-product alcohol, so as to quickly combine with the by-product alcohol. At the same time, spraying the azeotropic agent from the bottom applies an upward force to the azeotropic agent, which helps the azeotropic agent to quickly mix with the by-product alcohol and immediately perform azeotropic evaporation, enabling the azeotropic agent to exert the maximum efficiency in the shortest time, promoting the efficient removal of the by-product alcohol, and then promoting the transesterification reaction to proceed in the positive direction, improving the reaction efficiency and yield, and reducing the reaction time and energy consumption.
[0026] (4) The spraying pressure of the azeotropic agent of the present invention is 0.15 - 0.4 MPa. On the one hand, it ensures that the azeotropic agent can vaporize instantly when sprayed into the reactor, and the vaporized azeotropic agent directly takes away the by-product alcohol that forms an azeotrope with the azeotropic agent in the reaction system. On the other hand, under this pressure, the azeotropic agent in the pipeline for transporting the azeotropic agent can always remain in a liquid state when the preheating temperature is not lower than the boiling point of the azeotropic agent, effectively avoiding the vaporization of the azeotropic agent from affecting the pipeline safety, and thus ensuring the safety of the entire transesterification reaction process.
[0027] (5) When the present invention prevents the polymerization of unsaturated bonds in the raw material ester to form by-products and affect the product purity by adding an inhibitor to the reaction system. Specific embodiments
[0028] In order to better understand the above technical solutions, the following will specifically describe the above technical solutions in detail in combination with specific embodiments.
[0029] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0030] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.
[0031] (General embodiment)
[0032] A transesterification reaction process, in which the transesterification reaction is a reaction in which a raw material ester and a raw material alcohol react under the action of a catalyst to produce a product ester and a by-product alcohol, including the following process steps: adding the raw material ester, the raw material alcohol, and the catalyst into a reactor, reacting at a reaction temperature of 100 - 127 °C to obtain a reaction product; wherein, during the reaction process, an azeotropic agent is sprayed into the reactor at a spraying pressure of 0.15 - 0.4 MPa, and the azeotropic agent and the by-product alcohol perform azeotropic evaporation at the reaction temperature to remove the by-product alcohol; the molar ratio of the raw material ester to the raw material alcohol is 1.2 - 1.5:1, and the mass of the catalyst is 1 - 5% of the mass of the raw material alcohol; the azeotropic agent needs to be preheated to a first temperature before being sprayed into the reactor, and the first temperature is not lower than the boiling point of the azeotropic agent and not higher than the reaction temperature.
[0033] Among them, the catalyst is an organotin catalyst; the azeotropic agent is any one of straight-chain alkanes with 5 to 7 carbon atoms or any one of cycloalkanes with 5 to 7 carbon atoms.
[0034] When the raw material ester is methyl ester, the by-product alcohol is methanol, and the azeotropic agent includes cyclopentane, n-hexane, n-heptane, cyclohexane; among them, when the azeotropic agent is n-pentane, the mass ratio of n-pentane to methanol is 91:9; when the azeotropic agent is n-hexane, the mass ratio of n-hexane to methanol is 72:28; when the azeotropic agent is n-heptane, the mass ratio of n-heptane to methanol is 48.5:51.5; when the azeotropic agent is cyclohexane, the mass ratio to methanol is 62.8:37.2.
[0035] When the raw material ester is ethyl ester, the by-product alcohol is ethanol, and the azeotropic agent includes cyclopentane, n-hexane, n-heptane, n-octane; among them, when the azeotropic agent is n-pentane, the mass ratio of n-pentane to ethanol is 95:1; when the azeotropic agent is n-hexane, the mass ratio of n-hexane to ethanol is 79:21; when the azeotropic agent is n-heptane, the mass ratio of n-heptane to ethanol is 51:49; when the azeotropic agent is n-octane, the mass ratio of n-octane to ethanol is 22:78.
[0036] When there are unsaturated bonds in the raw material ester, a polymerization inhibitor needs to be introduced during the reaction process. The dosage of the polymerization inhibitor is 0.05% - 0.15% of the total mass of the unsaturated raw materials; the unsaturated raw materials include raw material alcohols containing unsaturated bonds and raw material esters containing unsaturated bonds.
[0037] The polymerization inhibitor includes phenothiazine.
[0038] (Example 1)
[0039] In this example, the raw material ester is dimethylaminoethyl methacrylate, and the raw material alcohol is dimethylethanolamine. The reaction mechanism of the transesterification
[0040] is as follows:
[0041] The specific process steps are as follows: Methyl methacrylate, dimethylethanolamine, the catalyst dibutyltin dilaurate, and the inhibitor phenothiazine are respectively added to a continuous reactor at a rate of 1450 kg / h, 900 kg / h, 36 kg / h, and 2.0 kg / h for reaction. The reaction temperature is controlled at 100 - 123 °C. During the reaction process, the azeotropic agent n-hexane at 90 °C is sprayed into the bottom of the continuous reactor at a rate of 700 kg / h, and the spraying pressure is controlled at 0.05 - 0.3 MPa. The azeotropic agent enters the reactor and comes into full contact with the materials in the reactor, and forms an azeotropic mixture with the by-product methanol. At the reaction temperature, the low-boiling azeotropic mixture evaporates by azeotropy, removing the by-product methanol from the reaction system. After continuous reaction for 6 h, the materials at the discharge port are taken out for gas chromatography analysis, and it is found that the molar conversion rate of the target product dimethylaminoethyl methacrylate is 89.7%.
[0042] (Example 2)
[0043] Ethyl acrylate, dimethylethanolamine, the catalyst dibutyltin oxide, and the inhibitor phenothiazine are respectively added to a continuous reactor at a rate of 1450 kg / h, 900 kg / h, 20 kg / h, and 2 kg / h for reaction. The reaction temperature is controlled at 100 - 125 °C. During the reaction process, the azeotropic agent n-hexane at 90 °C is sprayed into the bottom of the continuous reactor at a rate of 750 kg / h, and the spraying pressure is controlled at 0.05 - 0.3 MPa. The azeotropic agent enters the reactor and comes into full contact with the materials in the reactor, and forms an azeotropic mixture with the by-product ethanol. At the reaction temperature, the low-boiling azeotropic mixture evaporates by azeotropy, removing the by-product ethanol from the reaction system. After continuous reaction for 6 h, the materials at the discharge port are taken out for gas chromatography analysis, and it is found that the molar conversion rate of the target product dimethylaminoethyl acrylate is 93.2%.
[0044] (Comparative Example 1)
[0045] The difference between Comparative Example 1 and Example 1 is only that the azeotropic agent is not added during the reaction process; the other components and steps are the same as those in Example 1.
[0046] The specific process steps of Comparative Example 1 are as follows: Methyl methacrylate, dimethylethanolamine, the catalyst dibutyltin dilaurate, and the inhibitor phenothiazine are respectively added to a continuous reactor at a rate of 1450 kg / h, 900 kg / h, 36 kg / h, and 2.0 kg / h for reaction. The reaction temperature is controlled at 100 - 123 °C. After continuous reaction for 6 h, the materials at the discharge port are taken out for gas chromatography analysis, and it is found that the molar conversion rate of the target product dimethylaminoethyl methacrylate is 82.7%.
[0047] (Comparative Example 2)
[0048] The difference between Comparative Example 2 and Example 1 lies only in that the azeotropic agent is directly added during the reaction instead of being sprayed; the other components and steps are the same as those in Example 1.
[0049] The specific process steps of Comparative Example 2 are as follows: Methyl methacrylate, dimethylethanolamine, the catalyst dibutyltin dilaurate, and the inhibitor phenothiazine were added to a continuous reactor at 1450 kg / h, 900 kg / h, 36 kg / h, and 20 kg / h respectively for reaction. The reaction temperature was controlled at 100-123 °C. During the reaction, the azeotropic agent n-hexane was added at 700 kg / h. The azeotropic agent entered the reactor and combined with the by-product alcohol methanol to form an azeotropic mixture. At the reaction temperature, the low-boiling azeotropic mixture was azeotropically evaporated to remove the by-product alcohol methanol from the reaction system. After continuous reaction for 6 h, the material at the discharge port was taken out for gas chromatography analysis, and it was found that the molar conversion rate of the target product dimethylaminoethyl methacrylate was 85.3%.
[0050] From the comparison between Example 1 and Comparative Examples 1-2, it can be seen that under the same raw material formula, the transesterification reaction process of the present application has a higher conversion rate of the target product under the same reaction time, the energy consumption can be saved by 10%-30%, and the amount of solid waste generated can be reduced by more than 5%.
[0051] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A transesterification reaction process, wherein the transesterification reaction is a reaction in which a raw material ester and a raw material alcohol react under the action of a catalyst to generate a product ester and a by-product alcohol, characterized in that: The method comprises the following process steps: adding raw material ester, raw material alcohol and catalyst into a reactor, reacting at a reaction temperature to obtain a reaction product; spraying an azeotropic agent into the reactor during the reaction, and azeotropically evaporating the azeotropic agent and the by-product alcohol at the reaction temperature to remove the by-product alcohol.
2. The transesterification process according to claim 1, characterized in that: The molar ratio of the raw material ester to the raw material alcohol is 1.2-1.5:1; the mass of the catalyst is 1-5% of the mass of the raw material alcohol.
3. The transesterification process according to any one of claim 1, characterized in that: The catalyst is an organic tin catalyst.
4. The transesterification process according to claim 1, characterized in that: The raw material ester is an unsaturated ester, The general formula is: Among them, R1 is -H, -CH3; R2 is -CH3, -CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3.
5. The transesterification process according to claim 1, characterized in that: The reaction temperature is 95-130°C.
6. The transesterification process according to claim 1, characterized in that: The azeotropic agent is any one of the straight-chain alkanes with 5 to 7 carbon atoms, or any one of the cycloalkanes with 5 to 7 carbon atoms.
7. The transesterification process according to claim 1, characterized in that: The entrainer needs to be preheated to a first temperature before being sprayed into the reactor, and the first temperature is not lower than the boiling point of the entrainer and not higher than the reaction temperature.
8. The transesterification process according to claim 7, characterized in that: The injection pressure is 0.15-0.4 MPa.
9. The transesterification process according to claim 8, characterized in that: The azeotropic agent is sprayed into the reactor from the bottom.
10. The transesterification process according to any one of claims 1 to 9, characterized in that: A polymerization inhibitor needs to be added into the system, and the dosage of the polymerization inhibitor is 0.05% to 0.15% of the total mass of the unsaturated raw material ester.