A production system and production method for propylene glycol butyl ether and dipropylene glycol butyl ether

Abstract

The present invention relates to the technical field of propylene glycol ether synthesis, and particularly to a production system and a production method for propylene glycol butyl ether and dipropylene glycol butyl ether, which comprise the following steps: mixing n-butanol, potassium butoxide, a catalyst, and a first part of propylene oxide, and preheating to obtain a mixture; dividing a second part of propylene oxide into several batches; after the mixture is heat-exchanged to the reaction temperature, reacting it with the first batch of the second part of propylene oxide in a first reactor; after the reacted mixture is heat-exchanged and kept at a constant temperature to the reaction temperature, mixing it with the next batch and entering the next reactor for reaction; repeating the above steps in sequence until after reacting with the last batch, rectifying the material to respectively obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether, and tripropylene glycol butyl ether. The present invention reduces the reaction temperature through the co-use of multiple catalysts, and at the same time timely removes the reaction heat by adding raw materials in sections in the reactor, realizing the high-selectivity production of propylene glycol butyl ether.

Description

Technical Field

[0001] The present invention relates to the technical field of propylene glycol ether synthesis, and particularly to a production system and a production method for propylene glycol butyl ether and dipropylene glycol butyl ether. Background Art

[0002] Alcohol ether compounds are one of the important industrial derivatives of epoxides, and are a class of fine chemical products with very wide uses, known as the "universal solvent", and are widely used in industries such as coatings, inks, paints, printing, electronic chemicals, dyes, cleaning, textiles, etc. At present, the existing alcohol ether products on the market are mainly divided into two categories: ethylene glycol ether products and propylene glycol ether products. Ethylene glycol ether can be converted into methoxyacetic acid in the human body, which has an obstructive effect on metabolic functions, and thus has a toxic effect on the bone marrow, lymphoid tissue and developing fetus of animals. Therefore, ethylene glycol ether products are restricted by domestic and foreign regulations and standards, and their production volume is continuously decreasing. Propylene glycol ether is a low-toxic excellent solvent prepared by the reaction of propylene oxide with lower alcohols. Propylene glycol ethers mainly include propylene glycol methyl ether (PM), propylene glycol ethyl ether (PE), propylene glycol butyl ether (PB), etc. and their corresponding esters. Due to its chemical structure with unique hydrophilic and lipophilic dual functions, its toxicity is much lower than that of ethylene glycol ethers, and it is an excellent general solvent. Therefore, it is gradually replacing ethylene glycol ether products and is widely used in industries such as coatings, printing, dyes, inks, leather, electronic chemicals, PS plate cleaning, photosensitive glue, synthetic brake fluid, and jet fuel additives.

[0003] In the series of propylene glycol butyl ethers, due to its extremely low toxicity and relatively pleasant odor, it is a promising environmentally friendly solvent, used in industrial / household cleaner formulations, with extremely high safety, and is recognized by many developed countries, especially Japan. Also, because its HLB value is close to the middle of water / oil, it has great development space in coatings / inks / cleaner formulations.

[0004] There are many synthesis routes for propylene glycol butyl ether. Among them, the simplest and practically feasible one is the propylene oxide method. However, due to the asymmetry of the molecular structure of propylene oxide, the reaction produces two isomers: 1-butoxy-2-propanol and 2-butoxy-1-propanol. The former has good application performance and low toxicity, while the latter, as a by-product, has a boiling point close to that of the product and is difficult to separate. In addition, due to the properties of propylene oxide, the reaction product 1-butoxy-2-propanol will continue to react with propylene oxide to obtain by-products such as dipropylene glycol butyl ether and tripropylene glycol butyl ether, reducing the yield of propylene glycol butyl ether. Therefore, the higher the selectivity of the main reaction in the reaction stage, the better.

[0005] Therefore, there is an urgent need to provide a production method for propylene glycol butyl ether with high yield of propylene glycol butyl ether, low isomer content, and good reaction selectivity. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a production system and a production method for propylene glycol monobutyl ether and dipropylene glycol monobutyl ether, which are used to solve the problems of low yield, high isomer content, and many reaction by-products during the production of propylene glycol monobutyl ether in the prior art.

[0007] To achieve the above and other related purposes, the present invention is obtained through the following technical solutions.

[0008] The first aspect of the present invention is to provide a production system for propylene glycol monobutyl ether and dipropylene glycol monobutyl ether. The production system includes a pre-reaction tank, a reaction device, a storage tank, and a rectification device that are connected in sequence through pipelines;

[0009] The pre-reaction tank is used to mix n-butanol, potassium butoxide, a catalyst, and the first part of propylene oxide;

[0010] The reaction device includes a plurality of reaction units connected in series in sequence. The plurality of reaction units are used to react the raw materials in the pre-reaction tank with several batches of the second part of propylene oxide in sequence;

[0011] The reaction unit includes a heat exchanger and a reactor connected to the heat exchanger, which is used to heat the raw materials in the pre-reaction tank to the reaction temperature through the heat exchanger and then mix them with the corresponding batch of the second part of propylene oxide in the reactor;

[0012] The rectification device is used to separate the mixture after the reaction of the last batch of the second part of propylene oxide to obtain n-butanol, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monobutyl ether respectively.

[0013] The second aspect of the present invention is to provide a production method for propylene glycol monobutyl ether and dipropylene glycol monobutyl ether. The production method includes the following steps:

[0014] (1) Divide propylene oxide into the first part of propylene oxide and the second part of propylene oxide, mix n-butanol, potassium butoxide, a catalyst, and the first part of propylene oxide, and preheat to obtain a mixture; the catalyst includes an ether catalyst and a quaternary ammonium base catalyst;

[0015] (2) Divide the second part of propylene oxide into several batches;

[0016] (3) After the mixture is heated to the reaction temperature, react it with the first batch of the second part of propylene oxide in the first reactor;

[0017] (4) After the reaction, the mixture is heated and kept at a constant temperature to the reaction temperature, then mixed with the next batch of the second part of propylene oxide and enters the next reactor for reaction;

[0018] (5) Repeat step (4) successively until after the reaction with the last batch of the second part of propylene oxide, and then carry out rectification to obtain n-butanol, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether and tripropylene glycol monobutyl ether respectively.

[0019] As described above, a production system and a production method for propylene glycol monobutyl ether and dipropylene glycol monobutyl ether of the present invention have the following beneficial effects:

[0020] (1) The production method of the present invention uses a variety of catalysts to jointly catalyze, which is convenient for enhancing the reaction activity of propylene oxide and potassium butoxide, and then improving the conversion rates of n-butanol and propylene oxide. At the same time, the reaction temperature is controlled at 90-100 °C in the production method, so that the reaction selectivity is increased, and the proportion of by-products is less than 1%, which is convenient for purification; correspondingly, the reaction pressure is reduced to 6 atm, which can match a non-high-pressure reaction device;

[0021] (2) The reaction device used in the production method of the present invention is composed of multiple-stage reactions and a heat exchange part, which is convenient for timely removing the reaction heat, reducing the influence of local heat on the reaction, and further enhancing the reaction selectivity by controlling the temperature;

[0022] (3) The production method of the present invention controls the degree of reaction polymerization, so that n-butanol and propylene oxide mainly generate propylene glycol monobutyl ether and dipropylene glycol monobutyl ether under the action of a catalyst, realizing the maximization of economic benefits. Description of the Drawings

[0023] Figure 1 It shows a process flow chart of a production method for propylene glycol monobutyl ether and dipropylene glycol monobutyl ether of the present invention.

[0024] Description of the reference numerals in the drawings:

[0025] 1. Pre-reaction tank; 2. Reaction device; 3. Storage tank; 4. Rectification device. Detailed Description of the Invention

[0026] In order to make the invention purpose, technical solution and beneficial technical effects of the present invention clearer, the present invention will be further described in detail below in combination with embodiments. Those who are familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0027] The first aspect of the present invention is to provide a production system for propylene glycol monobutyl ether and dipropylene glycol monobutyl ether. The production system includes a pre-reaction tank 1, a reaction device 2, a storage tank 3 and a rectification device 4 that are connected in series through pipelines;

[0028] The pre-reaction tank 1 is used for mixing n-butanol, potassium butoxide, a catalyst and the first part of propylene oxide;

[0029] The reaction device 2 includes a plurality of reaction units connected in series in sequence. The plurality of reaction units are used to react the raw materials in the pre-reaction tank with several batches of the second part of propylene oxide in sequence;

[0030] The reaction unit includes a heat exchanger and a reactor connected to the heat exchanger. It is used to heat the raw materials in the pre-reaction tank to the reaction temperature through the heat exchanger and then mix them with the corresponding batch of the second part of propylene oxide in the reactor;

[0031] The distillation device 4 is used to separate the mixture after the reaction of the last batch of the second part of propylene oxide to obtain n-butanol, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether and tripropylene glycol monobutyl ether respectively.

[0032] In some embodiments of the present invention, the number of the reaction units is set to be more than two. Preferably, the number of the reaction units is set to be three.

[0033] In some embodiments of the present invention, the reactor is a tubular reactor. By using a segmented tubular reactor in the present invention for production, compared with a conventional tubular reactor or a kettle reactor, the reaction temperature can be effectively controlled to prevent the material from overheating, and the lower reaction pressure further reduces the implementation difficulty of the solution. The reactor of the present invention is adiabatic, and the reaction heat generated during the reaction process is removed through the heat exchanger between the two reactors, so as to maintain the stable temperature of the material. Then the material is mixed with the next batch of propylene oxide and enters the next reactor.

[0034] In some embodiments of the present invention, the inner diameter of the inner tube of the reactor is 5-50 mm. Specifically, the inner diameter of the inner tube can be 5-20 mm or 20-50 mm. Typically but not restrictively, for example, it can be 5 mm, 20 mm or 50 mm; the tube length is 3-20 m. Specifically, the tube length can be 3-12 m or 12-20 m. Typically but not restrictively, for example, it can be 3 m, 12 m or 20 m.

[0035] In some embodiments of the present invention, a mixer is provided between the heat exchanger and the reactor. The mixer is connected to the heat exchanger and the reactor, and is used to mix the raw materials passing through the heat exchanger and the second part of propylene oxide added in corresponding batches, and then transfer the mixed substance to the reactor. Specifically, when the reaction device 2 includes three reaction units, the reaction device 2 includes a first heat exchanger, a first mixer, a first reactor, a second heat exchanger, a second mixer, a second reactor, a third heat exchanger, a third mixer and a third reactor connected in sequence. The first heat exchanger is connected to the pre-reaction tank 1. The raw materials mixed in the pre-reaction tank 1 flow into the first heat exchanger, are heated to the reaction temperature, and then enter the first mixer. After being mixed with the first batch of the second part of propylene oxide, they jointly enter the first reactor for reaction. The reacted material is transferred to the second heat exchanger. After being heat-exchanged to the reaction temperature in the second heat exchanger, it enters the second mixer, and then is mixed with the next batch of the second part of propylene oxide, and jointly enters the second reactor for reaction. The reacted material is transferred to the third heat exchanger. After being heat-exchanged to the reaction temperature in the third heat exchanger, it enters the third mixer, and then is mixed with the next batch of the second part of propylene oxide, and jointly enters the third reactor for reaction, and then flows into the storage tank 3, and further flows to the distillation device 4 for distillation to obtain n-butanol, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether and tripropylene glycol monobutyl ether respectively. In this application, the reaction device 2 can operate continuously for a long time, during which the continuous addition and removal of materials are maintained. Several batches of the second part of propylene oxide in the raw materials can be added at the beginning of the reaction, or can be added after the material flows through the reactor. The above storage tank 3 is used to temporarily store the reaction products of the reaction unit and flow to the distillation device 4 for distillation.

[0036] The second aspect of the present invention lies in providing a production method of propylene glycol monobutyl ether and dipropylene glycol monobutyl ether, and the production method includes the following steps:

[0037] (1) Divide propylene oxide into a first part of propylene oxide and a second part of propylene oxide, mix n-butanol, potassium butoxide, a catalyst and the first part of propylene oxide, and preheat to obtain a mixture; the catalyst includes an ether catalyst and a quaternary ammonium base catalyst;

[0038] (2) Divide the second part of propylene oxide into several batches;

[0039] (3) After the mixture is heat-exchanged to the reaction temperature, react with the first batch of the second part of propylene oxide in the first reactor;

[0040] (4) After the reacted mixture is heat-exchanged and kept at the reaction temperature, mix with the next batch of the second part of propylene oxide, and enter the next reactor for reaction;

[0041] (5) Repeat step (4) successively until after the reaction with the last batch of the second part of propylene oxide, and then carry out rectification to obtain n-butanol, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether and tripropylene glycol monobutyl ether respectively.

[0042] In some embodiments of the present invention, the catalyst in the step (1) includes an ether catalyst and a quaternary ammonium base catalyst; the catalyst is composed of the ether catalyst and the quaternary ammonium base catalyst according to a mass ratio of 1-4:1-4; specifically, the mass ratio can be 1-2:1-2, 2-3:2-3, 3-4:3-4; typically but not limitedly, for example, it is 1:1, 1:2, 2:3; the ether catalyst is selected from one or more of crown ethers, ethylene glycol ethers, diethylene glycol ethers, and high molecular polyethers; preferably, the ether catalyst is a crown ether; the quaternary ammonium base catalyst is selected from one or more of tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, and dodecyltrimethylammonium hydroxide; preferably, the quaternary ammonium base catalyst is tetrabutylammonium hydroxide. The present invention has no special limitation on the source of the crown ether, and commercially available products of the crown ether commonly used in the art can be adopted. The present invention has no special limitation on the source of tetrabutylammonium hydroxide, and commercially available products of tetrabutylammonium hydroxide commonly used in the art can be adopted.

[0043] Among the above catalysts, the crown ether catalyst can complex with the potassium ion in potassium butoxide to enhance the attacking ability of potassium butoxide. At the same time, the quaternary ammonium base catalyst can form an active intermediate by combining with epoxy to reduce the energy barrier in the ring-opening process of the epoxy raw material. The synergistic use of the two catalysts can significantly reduce the reaction temperature and reaction rate required.

[0044] In order to inhibit the substitution of potassium butoxide on propylene oxide to the 2nd C to obtain isomers, the present invention adopts a way of using multiple catalysts together to achieve a lower reaction temperature. At the same time, in order to prevent the increase of isomers caused by local overheating, a tubular reactor with a segmented structure is designed. The low backmixing characteristic of the tubular reactor can significantly reduce the by-products such as dipropylene and tripropylene generated due to the overreaction of the product propylene glycol monobutyl ether. At the same time, the design of adding the propylene oxide material in batches in the device further inhibits the overreaction of the product propylene glycol monobutyl ether and reduces the generation of by-products such as dipropylene glycol monobutyl ether. In addition, since the overall temperature of the materials in the reaction process is relatively low, the required pressure for the reaction is also lower, reducing the requirements for the pressure resistance of the equipment and reducing the equipment cost and equipment maintenance cost.

[0045] In some embodiments of the present invention, the molar ratio of n-butanol, potassium butoxide, catalyst, and propylene oxide in step (1) is 300 - 900:2 - 6:0.1 - 0.2:300; specifically, the molar ratio can be 300 - 500:2 - 3:0.1 - 0.2:300, 500 - 900:3 - 6:0.1 - 0.2:300; typically but not restrictively, for example, it can be 300:2:0.1:300, 500:3:0.2:300, 900:6:0.2:300.

[0046] In some embodiments of the present invention, the preheating temperature in step (1) is 40 - 90°C; specifically, the temperature can be 40 - 70°C, 70 - 90°C; typically but not restrictively, for example, it can be 40°C, 70°C, 90°C; the preheating time is 10 - 30 min; specifically, the preheating time can be 10 - 15 min, 15 - 30 min; typically but not restrictively, for example, it can be 10 min, 15 min, 30 min.

[0047] In some embodiments of the present invention, the water content of n-butanol in step (1) is < 100 ppm.

[0048] In some embodiments of the present invention, the free base content of potassium butoxide in step (1) is < 50 ppm.

[0049] In some embodiments of the present invention, the reaction temperature in step (3) and / or step (4) is 90 - 100°C, the reaction pressure is 1 - 9 atm, and the reaction time is 15 - 90 min. Specifically, the reaction temperature can be 90 - 95°C, 95 - 100°C; typically but not restrictively, for example, it can be 90°C, 95°C, 100°C; the reaction pressure can be 1 - 5 atm, 5 - 9 atm; typically but not restrictively, for example, it can be 1 atm, 5 atm, 9 atm; the reaction time can be 15 - 45 min, 45 - 70 min, 70 - 90 min; typically but not restrictively, for example, it can be 15 min, 45 min, 70 min, 90 min.

[0050] In some embodiments of the present invention, the addition batches of the second part of propylene oxide in step (2) are set to 3 - 5 batches.

[0051] In some embodiments of the present invention, the molar ratio of n-butanol to each batch of the second part of propylene oxide is 1:0.1 - 0.4. Specifically, the molar ratio can be 1:0.1 - 0.3, 1:0.3 - 0.4; typically but not restrictively, for example, it can be 1:0.1, 1:0.3, 1:0.4.

[0052] In some embodiments of the present invention, the pressure of rectification in step (5) is 0.1 - 0.5 atm.

[0053] In some embodiments of the present invention, the rectification in step (5) is specifically as follows: at a pressure of 0.1 atm, set the reflux ratio to 1:1, and collect the fractions below 50 °C to recover n-butanol. After the internal temperature reaches 48 °C, change the reflux ratio to 4:1, and collect the fractions below 65 °C and merge them into the n-butanol recovery tank; after the internal temperature is higher than 70 °C, change the reflux ratio to 1:1, and collect the propylene glycol monobutyl ether product at 75 - 95 °C; then change the reflux ratio to 10:1, and collect the fractions below 105 °C and merge them into the propylene glycol monobutyl ether product collection tank; collect the fractions at 120 - 135 °C, which is dipropylene glycol monobutyl ether; change the reflux ratio to 25:1, and collect the fractions at 145 - 170 °C, which is tripropylene glycol monobutyl ether.

[0054] The present invention will be further illustrated by the following examples, which do not limit the scope of the present invention.

[0055] When the examples give a numerical range, it should be understood that unless otherwise specified in the present invention, any value between the two endpoints of each numerical range and any value between them can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art of this technology. For those conditions not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. All reagents or instruments without indicating the manufacturer are conventional products that can be obtained through commercial purchase. In addition to the specific methods, equipment, and materials used in the examples, according to the knowledge of those skilled in the art of this technology and the description of the present invention, any methods, equipment, and materials similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to implement the present invention.

[0056] In the following examples, the yield calculation method is actual yield / theoretical yield × 100%, and the purity determination method is gas chromatography. The chromatographic column is SK-5, the column temperature is 50 °C, the retention time is 2 min, the temperature is raised to 150 °C at a rate of 10 °C / min, and then raised to 300 °C at a rate of 20 °C / min, and the final temperature retention time is 10 min.

[0057] The gas chromatography of the present invention is Shimadzu GC-2010.

[0058] Example

[0059] Table 1 Reaction conditions of Examples 1 - 13 and Comparative Examples 1 - 3

[0060]

[0061] Example 1

[0062] This embodiment provides a production method of propylene glycol monobutyl ether and dipropylene glycol monobutyl ether. The process flow chart is as Figure 1 shown, and it includes the following steps:

[0063] Before the reaction starts, measure the free base content in the raw material potassium butoxide. It is qualified when it is lower than 50 ppm. Mix 37 kg of n-butanol and 336 g of potassium butoxide evenly, add 13.2 g of catalyst 18-crown-6, 13.0 g of catalyst tetrabutylammonium hydroxide, and 30 g of the first part of propylene oxide to obtain a mixture; after the mixture is mixed evenly, it enters the pre-reaction tank 1, and after stirring at 70 °C for more than 25 min, it is kept warm for standby;

[0064] The mixture is pumped into heat exchanger 1 by a metering pump and heated to 95 °C, then enters mixer 1 and is mixed with the first batch of the second part of propylene oxide and then enters reactor 1 together; the inner diameter of the inner tube of the tubular reactor is 20 mm and the total length is 12 m; adjust the raw material metering pump to control the usage amount and ratio of n-butanol and the first batch of the second part of propylene oxide. The addition amount of n-butanol in reactor 1 is 6.17 kg / h, and the addition amount of propylene oxide is 0.97 kg / h; the reacted mixture flows from reactor 1 to heat exchanger 2, and the material is kept at a constant temperature of 90 - 100 °C in heat exchanger 2, and after being mixed with the second batch of the second part of propylene oxide in mixer 2, it enters reactor 2. The addition amount of propylene oxide in reactor 2 is 0.97 kg / h; the material flows from reactor 2 to heat exchanger 3, and the material is kept at a constant temperature of 90 - 110 °C again in heat exchanger 3, and after being mixed with the third batch of the second part of propylene oxide in mixer 3, it enters reactor 3. The addition amount of propylene oxide in reactor 3 is 0.97 kg / h; the total reaction time is 6 h;

[0065] Use a gas chromatograph to detect the material ratio of the product in reactor 3. Among them, the proportion of n-butanol is 27.1%, the proportion of propylene glycol monobutyl ether is 67.5%, the isomer ratio is 0.1%, the proportion of dipropylene glycol monobutyl ether is 4.6%, and the proportion of tripropylene glycol monobutyl ether is 0.4%. The proportion of residual propylene oxide is 0.25%, and the conversion rate is 99.2%.

[0066] The material flows out of reactor 3 and enters storage tank 3 and cools down. Pump the material in storage tank 3 into the distillation device 4. Under a pressure of 0.1 atm, set the reflux ratio to 1:1, and collect the fractions below 50 °C to recover n-butanol. After the internal temperature reaches 48 °C, change the reflux ratio to 4:1, and collect the fractions below 65 °C and merge them into the n-butanol recovery tank. After the internal temperature is higher than 70 °C, change the reflux ratio to 1:1, collect the propylene glycol monobutyl ether product at 75 - 95 °C, and then change the reflux ratio to 10:1, and collect the fractions below 105 °C and merge them into the propylene glycol monobutyl ether product collection tank. Collect the fractions at 120 - 135 °C, which is dipropylene glycol monobutyl ether. Change the reflux ratio to 25:1, and collect the fractions at 145 - 170 °C, which is tripropylene glycol monobutyl ether.

[0067] 17.4 kg of propylene oxide was fed into the reaction, and 37.2 kg of the main product butyl propylene glycol ether was obtained with a yield of 93.8%; the by-products were 2.57 kg of dipropylene glycol butyl ether and 0.22 kg of tripropylene glycol butyl ether. Example 2

[0068] This example provides a method for producing butyl propylene glycol ether and dipropylene glycol butyl ether. The difference from Example 1 is that the amount of n-butanol added to Reactor 1 is 8.14 kg / h, the amount of the second part of propylene oxide added at each reactor is 1.28 kg / h, and the raw materials are added within 4.6 h. Others are exactly the same as in Example 1. The product components in Reactor 3 were detected using a gas chromatograph and the data were statistically analyzed. The data are shown in Tables 1 and 2. Example 3

[0069] This example provides a method for producing butyl propylene glycol ether and dipropylene glycol butyl ether. The difference from Example 1 is that the amount of n-butanol added to Reactor 1 is 4.89 kg / h, the amount of the second part of propylene oxide added at each reactor is 0.77 kg / h, and the raw materials are added within 7.6 h. Others are exactly the same as in Example 1. The product components in Reactor 3 were detected using a gas chromatograph and the data were statistically analyzed. The data are shown in Tables 1 and 2. Example 4

[0070] This example provides a method for producing butyl propylene glycol ether and dipropylene glycol butyl ether. The difference from Example 1 is that the amount of n-butanol used is 66.6 kg, and correspondingly, the feeding rate needs to be changed by adjusting the metering pump so that the amount of n-butanol added is 11.1 kg / h. Others are exactly the same as in Example 1. The product components in Reactor 3 were detected using a gas chromatograph and the data were statistically analyzed. The data are shown in Tables 1 and 2. Example 5

[0071] This example provides a method for producing butyl propylene glycol ether and dipropylene glycol butyl ether. The difference from Example 1 is that the amount of n-butanol used is 44.4 kg, and correspondingly, the feeding rate needs to be changed by adjusting the metering pump so that the amount of n-butanol added is 7.4 kg / h. Others are exactly the same as in Example 1. The product components in Reactor 3 were detected using a gas chromatograph and the data were statistically analyzed. The data are shown in Tables 1 and 2. Example 6

[0072] This example provides a method for producing butyl propylene glycol ether and dipropylene glycol butyl ether. The difference from Example 1 is that the amount of n-butanol used is 22.2 kg, and correspondingly, the feeding rate needs to be changed by adjusting the metering pump so that the amount of n-butanol added is 3.7 kg / h. Others are exactly the same as in Example 1. The product components in Reactor 3 were detected using a gas chromatograph and the data were statistically analyzed. The data are shown in Tables 1 and 2. Example 7

[0073] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of potassium butoxide is 672 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2. Example 8

[0074] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of potassium butoxide is 224 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2. Example 9

[0075] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of potassium butoxide is 112 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2. Example 10

[0076] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of catalyst 18-crown-6 is 26.4 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2. Example 11

[0077] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of catalyst 18-crown-6 is 6.6 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2. Example 12

[0078] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of catalyst tetrabutylammonium hydroxide is 26.0 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2. Example 13

[0079] This embodiment provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether. The difference from Example 1 is that the usage amount of catalyst tetrabutylammonium hydroxide is 6.5 g, and the others are exactly the same as those in Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and the data is statistically analyzed. The data is shown in Tables 1 and 2.

[0080] Comparative Example 1

[0081] This comparative example provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: the same feeding scheme as in Example 1 is used, the heat exchange cycle of heat exchanger II and heat exchanger III is closed, so that the reaction material is no longer controlled by other temperatures after being heated by heat exchanger I. That is, after the material is heated by heat exchanger I, it is transferred to reactor I for the first batch reaction of the second part of propylene oxide, and the reacted material is transferred to reactor II for the second batch reaction of the second part of propylene oxide, and then transferred to reactor III for the third batch reaction of the second part of propylene oxide. The others are exactly the same as in Example 1. A gas chromatograph is used to detect the product components in reactor III and statistical data is obtained.

[0082] Comparative Example 2

[0083] This comparative example provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: according to the same scheme as in Example 1, the usage amount of catalyst 18-crown-6 is changed to 0 g, that is, catalyst 18-crown-6 is not used, and only tetrabutylammonium hydroxide catalyst is used for the reaction. In addition, heat exchanger I, heat exchanger II, and heat exchanger III are adjusted so that the temperature of the material after heat exchange during the reaction process is 105 °C, and the reaction temperature is maintained at 100 - 110 °C. The others are exactly the same as in Example 1. A gas chromatograph is used to detect the product components in reactor III and statistical data is obtained.

[0084] Comparative Example 3

[0085] This comparative example provides a production method of propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: according to the same scheme as in Example 1, the usage amount of tetrabutylammonium hydroxide catalyst is changed to 0 g, that is, tetrabutylammonium hydroxide catalyst is not used, and only catalyst 18-crown-6 is used for the catalytic reaction. In addition, heat exchanger I, heat exchanger II, and heat exchanger III are adjusted so that the temperature of the material after heat exchange during the reaction process is 115 °C, and the reaction temperature is maintained at 110 - 120 °C. The others are exactly the same as in Example 1. A gas chromatograph is used to detect the product components in reactor III and statistical data is obtained.

[0086] Table 2 Product components in reactor III of Examples 1 - 13 and Comparative Examples 1 - 3

[0087]

[0088] Combined with Examples 1-3 and the data in Table 2, it can be seen that the contents of dipropylene glycol butyl ether and tripropylene glycol butyl ether in Example 3 are higher than those in Examples 1 and 2. The difference between Example 3 and Example 1 is that the reaction time of the materials in Example 1 is 6 h, and the reaction time in Example 3 is 7.6 h. When the reaction time of the materials is extended, it affects the reaction selectivity. When the reaction time is extended, the production amounts of dipropylene glycol butyl ether and tripropylene glycol butyl ether increase. When the reaction time is reduced, the raw material propylene oxide may face the problem of insufficient reaction.

[0089] Combined with Examples 1, 4-6 and the data in Table 2, it can be seen that the production amounts of dipropylene glycol butyl ether and tripropylene glycol butyl ether after the reaction in Example 6 are relatively large. After the reaction in Example 4, there is more unreacted butanol. The addition amount of butanol affects the reaction selectivity. When the dosage of butanol is too low, the contents of the by-products dipropylene glycol butyl ether and tripropylene glycol butyl ether increase. When the ratio of butanol to propylene oxide is greater than 5:3, the reaction selectivity is better and the by-products are less. However, too much addition of butanol may affect the energy consumption of the recycled butanol.

[0090] Combined with Examples 1, 7-9 and the data in Table 2, it can be seen that the addition of potassium butoxide has a great influence on the reaction activity. When the dosage of potassium butoxide is not less than 0.004 eq of butanol, the reaction can maintain a propylene oxide conversion rate of more than 97%, that is, Examples 7 and 8. When the content of potassium butoxide is not less than 1.2%, the production amount of propylene glycol butyl ether isomers increases. Appropriate addition of potassium butoxide helps to improve the reaction activity and the propylene oxide conversion rate.

[0091] Combined with Examples 1, 10-11 and the data in Table 2, it can be seen that when the amount of crown ether is increased in Example 10, the production amount of propylene glycol butyl ether isomers slightly increases. After the amount of the crown ether catalyst is reduced in Example 11, the reaction activity and the propylene oxide conversion rate decrease significantly.

[0092] Combined with Examples 1, 12-13 and the data in Table 2, it can be seen that when an excessive amount of quaternary ammonium base is added in Example 12, the production amount of propylene glycol butyl ether isomers increases significantly. When a small amount of quaternary ammonium base is added in Example 13, the reaction activity and the propylene oxide conversion rate decrease significantly.

[0093] Combined with Example 1 and Comparative Example 1 and the data in Table 2, it can be seen that the propylene oxide conversion rate in Comparative Example 1 is relatively low and the reaction selectivity is relatively low. The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, Heat Exchanger II and Heat Exchanger III are closed, and the temperature of the materials during the reaction is low at the front and high at the back, resulting in a relatively low propylene oxide conversion rate. At the same time, it affects the reaction selectivity, and the reaction selectivity is relatively low.

[0094] Combined with Example 1 and Comparative Example 2, and based on the data in Table 2, it can be seen that in the reaction of Comparative Example 2, the conversion rate of propylene oxide is relatively low, and the amounts of various by-products, especially isomers, increase significantly. The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, only tetrabutylammonium hydroxide is used to catalyze the reaction, and the reaction temperature is changed to 100 - 110 °C. When only tetrabutylammonium hydroxide is used as the catalyst for the reaction, the reaction activity is low and the selectivity is poor.

[0095] Combined with Example 1 and Comparative Example 3, and based on the data in Table 2, it can be seen that in the reaction of Comparative Example 3, the conversion rate of propylene oxide is lower than 90%, and the amounts of dipropylene glycol butyl ether and tripropylene glycol butyl ether formed are relatively large. The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, only 18-crown-6 is used to catalyze the reaction, the reaction activity is relatively low, and the reaction selectivity is poor.

[0096] The above embodiments merely illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, characterized in that: The production system adopted in the production method comprises a pre-reaction tank (1), a reaction device (2), a storage tank (3) and a distillation device (4) which are sequentially connected by pipelines; The pre-reaction tank (1) is used to mix n-butanol, potassium butoxide, a catalyst, and the first part of propylene oxide; The reaction device (2) comprises a plurality of reaction units connected in series, and the plurality of reaction units are used to react the raw materials in the pre-reaction tank with the second part of several batches of propylene oxide in sequence; The reaction unit comprises a heat exchanger and a reactor connected to the heat exchanger, which is used to heat the raw materials in the pre-reaction tank to the reaction temperature through the heat exchanger and then mix them with the second part of the corresponding batch of propylene oxide in the reactor; The distillation device (4) is used to separate the mixture after the last batch of the second part of propylene oxide is reacted; The production method comprises the following steps: (1) dividing propylene oxide into a first part of propylene oxide and a second part of propylene oxide, mixing n-butanol, potassium butoxide, a catalyst and the first part of propylene oxide, and preheating to obtain a mixture; the catalyst comprises an ether catalyst and a quaternary ammonium base catalyst; the catalyst comprises an ether catalyst and a quaternary ammonium base catalyst in a mass ratio of 1-4:1-4; the ether catalyst is selected from one or more of crown ethers, ethylene glycol ethers, diethylene glycol ethers, and polymer polyethers; the quaternary ammonium base catalyst is selected from one or more of tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, and dodecyltrimethylammonium hydroxide; (2) dividing the second portion of propylene oxide into a plurality of batches; (3) exchanging heat to the reaction temperature of the mixture and reacting it with the first batch of the second part of propylene oxide in the first reactor; the reaction temperature is 90-95° C., the reaction pressure is 1-9 atm, and the reaction time is 15-90 min; (4) The reacted mixture is subjected to heat exchange and constant temperature to the reaction temperature, and then mixed with the next batch of the second part of propylene oxide and enters the next reactor for reaction; (5) Repeat step (4) until the last batch of the second part of propylene oxide is reacted, and then the material is distilled to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively.

2. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 1, characterized in that: The step (1) further includes one or more of the following features: 11) In step (1), the molar ratio of n-butanol, potassium butoxide, catalyst and propylene oxide is 300-900:2-6:0.1-0.2:300; 12) The preheating temperature in step (1) is 40-90°C and the preheating time is 10-30 minutes; 13) The water content of n-butanol in step (1) is less than 100 ppm; 14) In step (1), the free alkali content of potassium butoxide is less than 50 ppm.

3. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 1, characterized in that: The second portion of propylene oxide added in step (2) is set to be 3-5 batches.

4. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 1, characterized in that: The distillation pressure in step (5) is 0.1-0.5 atm.

5. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 1, characterized in that: The inner diameter of the inner tube of the reactor is 5-50 mm, and the tube length is 3-20 mm.

6. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 1, characterized in that: A mixer is provided between the heat exchanger and the reactor, the mixer is connected with the heat exchanger and the reactor, and is used to mix the raw materials passing through the heat exchanger and the second part of propylene oxide added in the corresponding batch, and then transfer the mixed substances to the reactor.

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