CN111675615A - A kind of preparation method and device of methyl myristate - Google Patents

Abstract

The invention provides a preparation method and device of methyl myristate. The preparation method includes the following steps: mixing and stirring tetradecanoic acid and methanol according to a molar ratio of 1:(2-6) to form a mixture, heating to 50-60° C., and adding 10-30 wt % of solid acid by mass of the mixture The catalyst carries out the esterification reaction. The preparation method of the present invention uses a solid acid catalyst to replace the liquid acid catalyst, the specific surface area and pore volume of the solid acid catalyst are relatively large, good selectivity and reactivity are ensured, product separation and purification are easy, and the solid acid catalyst can be used repeatedly. It avoids equipment corrosion and environmental pollution, and enables enterprises to produce continuously; and under the specific conditions of the catalyst dosage of 10-30wt% of the mixture, the reaction efficiency is improved, the occurrence of side reactions is suppressed, and the conversion rate of the product reaches 97.8 %-99.7%, which improves the yield of the final product, methyl myristate.

Description

A kind of preparation method and device of methyl myristate

technical field

The present invention relates to the preparation field of methyl myristate, in particular to a preparation method and device of methyl myristate.

Background technique

Due to the depletion of conventional non-renewable diesel and the increase in anthropogenic emissions of greenhouse gases, biodiesel is regarded as a promising alternative energy source and has received extensive attention in recent years. As one of the main components of biodiesel, methyl myristate has the advantages of high cetane number, high flash point, good emission characteristics, renewability and excellent biodegradability, and is regarded as a promising diesel additives and fuel alternatives. In addition to being used in biodiesel, methyl myristate can also be used in honey, coconut and other edible flavors and daily flavors, and can also be used in the preparation of organic chemicals. Therefore, as an important fatty acid methyl ester, methyl myristate has great application value, and it is of great practical significance to develop a green and economical process route for methyl myristate.

At present, the industrial production of methyl tetradecanoate generally uses tetradecanoic acid and methanol as raw materials, and concentrated sulfuric acid as a catalyst to carry out esterification reaction. The concentrated sulfuric acid has quite high activity, but it has serious equipment corrosion and is difficult to continuous production. , strict acidity requirements, serious environmental pollution, etc., and the product is difficult to separate and purify, and there are many by-products, which greatly reduces the yield.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a method for preparing methyl myristate, which uses a solid acid catalyst to replace the liquid acid catalyst, and the specific surface area and pore volume of the solid acid catalyst are relatively large, ensuring good selectivity and reactivity, easy to separate and purify products, and can be used repeatedly, avoiding equipment corrosion and environmental pollution, enabling enterprises to continue production; and under the specific conditions of specific solid acid catalyst dosage, greatly improved The reaction efficiency inhibits the occurrence of side reactions, can make the conversion rate of the product reach 97.8%-99.7%, and improves the yield of the final product, methyl myristate.

The second object of the present invention is to provide a device using the above preparation method, which has low cost, convenient operation and high yield of methyl myristate obtained by using the device.

In order to realize the above-mentioned purpose of the present invention, the following technical solutions are specially adopted:

The invention provides a preparation method of methyl myristate, comprising the following steps:

The tetradecanoic acid and methanol are mixed and stirred according to a molar ratio of 1:(2-6) to form a mixture, heated to 50-60° C., and 10-30 wt % of the solid acid catalyst based on the mass of the mixture is added to carry out esterification reaction.

In the prior art, what is generally used in the industrial production of methyl tetradecanoate is to use tetradecanoic acid and methanol as raw materials, and the concentrated sulfuric acid is used as a catalyst to carry out the esterification reaction, and the concentrated sulfuric acid has quite high activity, but it has serious equipment corrosion. , Difficult to continuous production, strict acidity requirements, serious environmental pollution and other disadvantages, and the product is difficult to separate and purify, with many by-products, which greatly reduces the yield.

The preparation method of the present invention uses a solid acid catalyst to replace the liquid acid catalyst, the specific surface area and pore volume of the solid acid catalyst are relatively large, good selectivity and reactivity are ensured, product separation and purification are easy, and the solid acid catalyst can be used repeatedly for many times , avoid equipment corrosion and environmental pollution, and enable enterprises to produce continuously; and under the specific conditions of the catalyst dosage of 10-30wt% of the mixture, the reaction efficiency is greatly improved, the occurrence of side reactions is suppressed, and the product is The conversion rate reaches 97.8%-99.7%, which greatly improves the yield and quality of the final product, methyl myristate.

In the solution of the present invention, not only a solid acid catalyst is used to replace the traditional liquid acid catalyst, but also the amount of the adopted solid acid catalyst is optimized, because when the amount of the catalyst is too large, it will not only increase the burden of subsequent treatment, but also will not further To increase the conversion rate of the reaction, if the amount of catalyst is too small, the desired catalytic effect cannot be achieved, so a suitable amount of catalyst is necessary.

Preferably, the dosage of the solid acid catalyst is 15-25 wt % of the mass of the mixture; preferably, the dosage of the solid acid catalyst is 20 wt %. The inventors have found through a lot of practice that the specific surface area of the solid acid catalyst is large, so that the catalyst generated by the supported metal ions can obtain good dispersion, and the reactant can be adsorbed on the outer surface structure of the cavity. The concentration of the catalyst at the center of the reaction is greatly increased by the reaction, thereby greatly improving the reaction activity. When the optimal amount of the catalyst is 20wt%, the conversion rate of the product reaches 99.7%.

Preferably, the solid acid catalyst is at least one of a cation exchange resin and a solid super acid; the solid acid catalyst is a cation exchange resin, and compared with other solid acid catalysts, the cation exchange resin and the solid super acid have better stability , easier to separate from reactants and can be used repeatedly, especially the cation exchange resin not only has excellent catalytic performance, but also has high mechanical strength.

Preferably, the cation exchange resin is Amberlyst 39wet, Amberlyst 36wet or Amberlyst 35wet. Preferably, the cation exchange resin is Amberlyst 39wet. Amberlyst 39wet, Amberlyst36wet or Amberlyst 35wet are all ion exchange resin series produced by Dow Chemical, especially Amberlyst39wet is a macroporous strong acid catalyst with low degree of crosslinking, and its open pore structure is especially suitable for esterification.

Preferably, the stirring rate is 400 rpm-600 rpm, and controlling a suitable stirring rate can improve the conversion rate of raw materials, and the produced methyl tetradecanoate has better performance.

Preferably, after the esterification reaction is carried out, the step of quantitatively analyzing the reaction product after the esterification reaction is further included, and the quantitative analysis adopts a gas chromatograph;

Preferably, the operating conditions of the gas chromatograph are that the carrier gas is N ₂ , the pre-column pressure: 45.2 kPa; the makeup gas (N 2 ) flow rate is: 30 mL/min; H ₂ : 40 mL/min; Air: 400 mL/min ; The temperature of the vaporization chamber is 270-280°C, the temperature of the detector is 280-290°C, and the injection volume is 0.5 μL. Qualitative and quantitative analysis of the sample by gas chromatograph can quickly and accurately control and analyze the esterification reaction process and product quality and yield.

The present invention also provides a preparation device using the above preparation method, including a premix tank for premixing raw materials, the premix tank is connected to a full mixing kettle, and a solid mixing kettle is provided on the full mixing kettle for introducing solids. The catalyst inlet of the acid catalyst and the raw material inlet for feeding the raw material are provided with a temperature control device on the complete mixing kettle.

Preferably, a product outlet is provided on the side wall of the fully mixed kettle, and the reaction product enters the catalyst separator from the product outlet for separation and recovery of the catalyst;

Preferably, the top of the catalyst separator is provided with a liquid phase outlet, and the liquid phase outlet is connected with a membrane filter for separating the catalyst in the liquid phase material;

Preferably, the bottom of the membrane filter is provided with a catalyst recovery port, the side wall of the membrane filter is provided with a product outlet for discharging purified products, and the catalyst recovery port is connected to the side of the catalyst separator. A wall connection is used for part of the material to be returned to the catalyst separator for further purification and separation.

Preferably, a first catalyst outlet is arranged at the bottom of the total mixing kettle; a second catalyst outlet is arranged at the bottom of the catalyst separator, and the second catalyst outlet and the first catalyst outlet are communicated and recovered together.

Preferably, the preparation device further comprises a catalyst regenerator, and the side wall of the catalyst regenerator is respectively connected with the first catalyst outlet and the second catalyst outlet; preferably, the side wall of the catalyst regenerator is connected to the The catalyst inlet is connected for returning the regenerated catalyst to the fully mixed tank.

Preferably, the product outlet is connected to a first rectification column for separating the product from methanol; a column top condenser is provided on the top of the first rectification column, and the condensate from the column top condenser A part is returned to the first rectification tower, and a part is sent to the premixing tank.

Preferably, a heavy component outlet is provided at the bottom of the first rectification tower, and an extraction column is connected to the heavy component outlet for extraction and purification of products.

Preferably, an extraction solvent nozzle is provided at the top of the extraction tower, and an extraction liquid outlet is provided at the bottom of the extraction tower, and the extraction liquid outlet is connected to the second rectifying tower for removing the extraction solvent.

Compared with the prior art, the beneficial effects of the present invention are:

The preparation method of the present invention uses a solid acid catalyst to replace the liquid acid catalyst, the specific surface area and pore volume of the solid acid catalyst are relatively large, good selectivity and reactivity are ensured, product separation and purification are easy, and the solid acid catalyst can be used repeatedly for many times. It avoids equipment corrosion and environmental pollution, and enables enterprises to produce continuously; and under the specific conditions of the catalyst dosage of 10-30wt% of the mixture, the reaction efficiency is greatly improved, the occurrence of side reactions is suppressed, and the conversion of products can be achieved. The yield reaches 97.8%-99.7%, which improves the yield of the final product, methyl myristate.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be considered limiting of the invention. Also, the same components are denoted by the same reference numerals throughout the drawings. In the attached image:

Fig. 1 is the structural representation of the preparation device of methyl myristate provided in the embodiment of the present invention;

Fig. 2 is the influence relation schematic diagram of the catalyst dosage of embodiment 1-5 on myristate esterification;

Fig. 3 is the influence relation schematic diagram of embodiment 6-9 different catalysts on myristate esterification;

Fig. 4 is the gas chromatogram of the obtained reaction product of the embodiment of the present invention 3;

Figure 5 is a gas chromatogram of the product obtained in Example 10 of the present invention.

Description of drawings:

1-Premixing tank; 2-Full mixing tank;

21- Raw material import; 22- Catalyst import;

23-product outlet; 24-first catalyst outlet;

201- temperature control device;

3-catalyst separator; 31-liquid phase outlet;

301-membrane filter; 3010-product export;

32- the second catalyst outlet; 4- the first rectifying column;

401- tower top condenser; 42- heavy component outlet;

5-extraction tower; 51-extract outlet;

501-extraction solvent nozzle; 6-second distillation column;

7- Catalyst regenerator.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments, It is only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. 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. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

In order to illustrate the technical solutions of the present invention more clearly, the following descriptions are given in the form of specific embodiments.

Example 1

Using the device shown in Figure 1, the tetradecanoic acid and methanol were introduced into the premix tank 1 at a molar ratio of 1:5, and stirred at a speed of 400rpm-600rpm until the tetradecanoic acid was completely dissolved to form a mixture and then entered from the raw material inlet 21. Total mixing kettle 2;

At the same time, 10wt% catalyst Amberlyst 39wet of the mixture mass is added into the fully mixed kettle 2 through the catalyst inlet 22 to carry out the esterification reaction, and the fully mixed kettle 2 is provided with a temperature control device 201 for controlling the temperature in the esterification reaction process to maintain At 50-60° C., the reaction is sampled at certain time intervals and analyzed by gas chromatography. The operating conditions of the gas chromatograph are that the carrier gas is N ₂ , the pre-column pressure: 45.2kPa; the makeup gas (N ₂ ) flow rate is: 30mL/min; H ₂ : 40mL/min; Air: 400mL/min; the temperature of the gasification chamber is 270-280°C, the temperature of the detector is 280-290°C, and the injection volume is 0.5 μL.

After the reaction product comes out from the product outlet 23, it enters the catalyst separator 3 to separate the catalyst. The top of the catalyst separator 3 is provided with a liquid phase outlet 31, and the liquid phase outlet 31 is connected with a membrane filter 301 for separating the liquid phase materials. The catalyst, the side wall of the membrane filter 301 is provided with a product outlet 3010 to discharge the purified product, and the purified product from the product outlet 3010 enters the first rectifying tower 4 for rectification to separate the product from methanol , the tower top of the first rectifying tower 4 is provided with a tower top condenser 401, and a part of the condensate from the tower top condenser 401 is returned to the first rectifying tower 4, and a part goes to the premixing tank 1, the first rectifying liquid The bottom of the tower 4 is provided with a heavy component outlet 42, and the product after isolating the methanol enters the extraction tower 50 from the heavy component outlet 42 to carry out product extraction and purification. The top of the tower 5 enters and extracts the product by spraying, and the bottom of the extraction tower 50 is provided with an extraction liquid outlet 51, and the extraction liquid enters the second rectifying tower 6 after the extraction liquid 51 outlet comes out to remove the extraction solvent. , the final product methyl myristate after removing the organic solvent is extracted from the bottom of the second rectifying tower 6.

In addition, the bottom of the total mixing kettle 2 is provided with a first catalyst outlet 24, and the bottom of the catalyst separator 3 is provided with a second catalyst outlet 32. The first catalyst outlet 24 and the second catalyst outlet 32 are connected and recovered together. In this embodiment, , the preparation device further includes a catalyst regenerator 7, the side wall of the catalyst regenerator 7 is respectively connected with the first catalyst outlet 24 and the second catalyst outlet 32; the side wall of the catalyst regenerator 7 is connected with the catalyst inlet 22 is connected for returning the regenerated catalyst to the fully mixed tank 2 for utilization.

Example 2

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 39wet is used at 15 wt % of the mass of the mixture.

Example 3

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 39wet is used in 20 wt% of the mass of the mixture. The gas chromatogram of the specific product is shown in Figure 3.

Example 4

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 39wet is used at 25 wt % of the mass of the mixture.

Example 5

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 39wet is used in 30 wt % of the mass of the mixture.

As can be seen from Figure 2, by comparing the amount of the catalyst in Examples 1-5 of the present invention, the solid acid catalyst content of the present invention is in the specific condition of the amount of the mixture of 10-30wt%, so that the conversion rate of the product reaches 97.8%- 99.7%, especially when the amount of the mixture is 30wt%, the conversion rate of the product reaches the highest point of 99.7%. It can be seen that the optimal catalyst dosage is 30wt%.

Example 6

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 15wet, which is 10 wt % of the mass of the mixture, is added to the total mixing kettle 2.

Example 7

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 35wet, which is 10 wt % of the mass of the mixture, is added to the total mixing kettle 2.

Example 8

The operation steps of this example are the same as those of Example 1, except that the catalyst Amberlyst 36wet, which is 10 wt % of the mass of the mixture, is added to the total mixing kettle 2.

Example 9

The operation steps of this example are the same as those of Example 1, except that the catalyst Lewatit K2620, which is 10 wt % of the mass of the mixture, is added to the total mixing kettle 2.

As can be seen from Figure 3, by changing the type of catalyst, and comparing the above Examples 6-9 with Example 1, the solid acid catalyst Amberlyst 39wet has the best activity, and the obtained methyl tetradecanoate has the highest yield.

Example 10

The operation steps of this example are the same as those of Example 3, except that the tetradecanoic acid and methanol are passed into the premix tank 1 according to the molar ratio of 1:3, and the gas chromatogram of the specific product is shown in FIG. 4 .

It can be seen from the gas chromatograms in Fig. 4 and Fig. 5 that the methyl tetradecanoate obtained by adopting the scheme of the present invention has achieved an ideal yield.

In a word, the preparation method of the present invention uses a solid acid catalyst to replace the liquid acid catalyst, and the specific surface area and pore volume of the solid acid catalyst are relatively large, which ensures good selectivity and reactivity, is easy to separate and purify products, and can be used repeatedly for many times. Second, it avoids equipment corrosion and environmental pollution, and enables enterprises to produce continuously; and under the specific conditions of the catalyst dosage of 10-30wt% of the mixture, the reaction efficiency is greatly improved, the occurrence of side reactions is suppressed, and the product The conversion rate reaches 97.8%-99.7%, which improves the yield and quality of the final product, methyl myristate.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (10)

1. A preparation method of methyl myristate is characterized by comprising the following steps:

mixing and stirring the tetradecanoic acid and the methanol according to the molar ratio of 1 (2-6) to form a mixture, heating to 50-60 ℃, and adding a solid acid catalyst accounting for 10-30 wt% of the mixture for esterification reaction.

2. The method according to claim 1, wherein the solid acid catalyst is used in an amount of 15 to 25 wt% based on the mass of the mixture;

preferably, the solid acid catalyst is used in an amount of 20 wt% of the mass of the mixture.

3. The method according to claim 1, wherein the solid acid catalyst is at least one of a cation exchange resin and a solid super acid;

preferably, the solid acid catalyst is a cation exchange resin;

preferably the type of cation exchange resin is at least one of Amberlyst39wet, Amberlyst36wet, Amberlyst35 wet;

preferably, the cation exchange resin is of the type Amberlyst39 wet.

4. The method of claim 1, wherein the mixing and stirring rate is 400rpm to 600 rpm.

5. The method according to claim 1, further comprising a step of performing quantitative analysis of the reaction product after the esterification reaction, wherein the quantitative analysis is performed by using a gas chromatograph;

preferably, the gasification temperature of the gas chromatograph is 270-280 ℃, and the detection temperature is 280-290 ℃.

6. A preparation device adopting the preparation method of methyl myristate according to any one of claims 1-5, characterized by comprising a premixing tank for premixing raw materials, wherein the premixing tank is connected with a full mixing kettle, the full mixing kettle is provided with a catalyst inlet for introducing a solid acid catalyst and a raw material inlet for introducing raw materials, and the full mixing kettle is provided with a temperature control device.

7. The preparation device of claim 6, wherein the side wall of the complete mixing kettle is provided with a product outlet, and reaction products enter the catalyst separator from the product outlet for separation and recovery of the catalyst;

preferably, a liquid phase outlet is arranged at the top of the catalyst separator, and a membrane filter is connected to the liquid phase outlet for separating the catalyst in the liquid phase material;

preferably, the bottom of the membrane filter is provided with a catalyst recovery port, the side wall of the membrane filter is provided with a product outlet for discharging purified products, and the catalyst recovery port is connected with the side wall of the catalyst separator for returning part of materials to the catalyst separator to continue purification and separation.

8. The preparation device of claim 7, wherein the bottom of the complete mixing kettle is provided with a first catalyst outlet; a second catalyst outlet is formed in the bottom of the catalyst separator, and the second catalyst outlet is communicated with the first catalyst outlet for common recovery;

preferably, the preparation device further comprises a catalyst regenerator, and the side wall of the catalyst regenerator is respectively connected with the first catalyst outlet and the second catalyst outlet;

preferably, the side wall of the catalyst regenerator is connected to the catalyst inlet for the regenerated catalyst to be returned to the complete mixing tank.

9. The production apparatus according to claim 7, wherein the product outlet is connected to a first rectification column for separating a product from methanol; and a tower top condenser is arranged at the tower top of the first rectifying tower, part of condensate coming out of the tower top condenser returns to the first rectifying tower, and part of condensate goes to the premixing tank.

10. The device as claimed in claim 7, wherein a heavy component outlet is arranged at the bottom of the first rectifying tower, and an extraction tower is connected to the heavy component outlet for product extraction and purification;

preferably, the top of the extraction tower is provided with an extraction solvent spray nozzle, the bottom of the extraction tower is provided with an extraction liquid outlet, and the extraction liquid outlet is connected with the second rectification tower to remove the extraction solvent.

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