Production system and production method of propylene glycol butyl ether and dipropylene glycol butyl ether

Abstract

The invention relates to the technical field of propylene glycol ether synthesis, in particular to a production system and a production method of propylene glycol butyl ether and dipropylene glycol butyl ether, and the production method comprises the following steps: mixing n-butyl alcohol, potassium butoxide, a catalyst and a first part of epoxypropane, and preheating to obtain a mixture; dividing the second part of epoxypropane into a plurality of batches; carrying out heat exchange on the mixture to a reaction temperature, and reacting the mixture with a first batch of a second part of epoxypropane in a first reactor; after the reacted mixture is subjected to heat exchange and constant temperature to the reaction temperature, the mixture is mixed with the next batch and enters the next reactor to react; the steps are repeated in sequence until the materials react with the last batch, then the materials are rectified, and n-butyl alcohol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether are obtained respectively. According to the present invention, the reaction temperature is reduced through the common use of a variety of catalysts, and the reaction heat is timely removed through the manner of adding the raw materials in the reactor in the segmented manner so as to achieve the high selectivity production of propylene glycol butyl ether.

Description

Technical Field

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

[0002] Alcohol ether compounds are one of the important industrial derivatives of epoxy compounds. They are a kind of fine chemical products with a wide range of uses. They are known as "universal solvents" and are widely used in coatings, inks, paints, printing, electronic chemicals, dyes, cleaning, textiles and other industries. At present, the existing alcohol ether products on the market are mainly ethylene glycol ethers and propylene glycol ethers. Ethylene glycol ethers can be converted into methoxyacetic acid in the human body, which has a barrier effect on metabolic function, thereby causing toxic effects on the bone marrow, lymphatic tissue and developing fetuses of animals. Therefore, ethylene glycol ether products are restricted by domestic and foreign regulations and standards, and their production continues to decline. Propylene glycol ether is a low-toxic excellent solvent made by the reaction of propylene oxide and low-carbon 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 unique chemical structure with dual hydrophilic and lipophilic functions, its toxicity is much lower than that of glycol ethers. It is an excellent general solvent and is gradually replacing glycol ether products. It is widely used in coatings, printing, dyes, inks, leather, electronic chemicals, PS plate cleaning, photosensitive adhesives, synthetic brake fluids, jet fuel additives and other industries.

[0003] Propylene glycol butyl ether series is a promising environmentally friendly solvent in the propylene glycol ether series due to its extremely low toxicity and pleasant smell. It is used in industrial / household cleaning agent formulations with extremely high safety and is recognized by many developed countries, especially Japan. Because its HLB value is close to the middle of water / oil, it has great development space in coating / ink / cleaner formulations.

[0004] There are many synthetic routes for propylene glycol butyl ether, among which the simplest and most practical 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 is a by-product with a boiling point close to the product and 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 method for producing propylene glycol butyl ether with high yield, low isomer content and good reaction selectivity. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a production system and a production method of propylene glycol butyl ether and dipropylene glycol butyl ether, so as to solve the problems of low yield, high isomer content and large number of reaction by-products in the production of propylene glycol butyl ether in the prior art.

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

[0008] The first aspect of the present invention is to provide a production system of propylene glycol butyl ether and dipropylene glycol butyl ether, the production system comprising a pre-reaction tank, a reaction device, a storage tank and a distillation device which are sequentially connected by pipelines; The pre-reaction tank is used to mix n-butanol, potassium butoxide, catalyst, and the first part of propylene oxide; The reaction device comprises a plurality of reaction units connected in series in sequence, 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 is used to separate the mixture after the last batch reaction of the second part of propylene oxide to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively.

[0009] The second aspect of the present invention is to provide a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, the production method comprising the following steps: (1) dividing propylene oxide into a first propylene oxide part and a second propylene oxide part, mixing n-butanol, potassium butoxide, a catalyst, and the first propylene oxide part, and preheating to obtain a mixture; the catalyst comprises an ether catalyst and a quaternary ammonium base catalyst; (2) dividing the second portion of propylene oxide into a plurality of batches; (3) exchanging heat of the mixture to a reaction temperature and reacting the mixture with a first batch of the second part of propylene oxide in a first reactor; (4) The reacted mixture is subjected to heat exchange and thermostating 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 distill to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively.

[0010] As described above, the production system and method of propylene glycol butyl ether and dipropylene glycol butyl ether of the present invention have the following beneficial effects: (1) The production method of the present invention is convenient for enhancing the reaction activity of propylene oxide and potassium butoxide by using multiple catalysts for co-catalysis, thereby improving the conversion rate of n-butanol and propylene oxide. At the same time, the reaction temperature is controlled at 90-100°C in the production method to increase the reaction selectivity, and the proportion of by-products is less than 1%, which is convenient for purification; correspondingly, the reaction pressure is reduced to 6atm, which can match non-high-pressure reaction equipment; (2) The reaction device used in the production method of the present invention is composed of multiple reaction and heat exchange parts, which facilitates the timely removal of reaction heat, reduces the impact of local heat on the reaction, and further enhances the reaction selectivity by controlling the temperature; (3) The production method of the present invention controls the degree of polymerization of the reaction so that n-butanol and propylene oxide mainly generate propylene glycol butyl ether and dipropylene glycol butyl ether under the action of the catalyst, thereby maximizing the economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Shown is a process flow chart of a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to the present invention.

[0012] Description of reference numerals: 1. Pre-reaction tank; 2. Reaction device; 3. Storage tank; 4. Distillation device. DETAILED DESCRIPTION

[0013] In order to make the invention objectives, technical solutions and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0014] The first aspect of the present invention is to provide a production system of propylene glycol butyl ether and dipropylene glycol butyl ether, the production system comprising 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, catalyst, and the first part of propylene oxide; The reaction device 2 comprises a plurality of reaction units connected in series in sequence, 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 to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively.

[0015] In some embodiments of the present invention, the number of the reaction units is more than two, and preferably, the number of the reaction units is three.

[0016] In some embodiments of the present invention, the reactor is a tubular reactor. The present invention adopts a segmented tubular reactor to effectively control the reaction temperature to prevent the material from overheating compared to a conventional tubular reactor or a kettle reactor, and the lower reaction pressure also further reduces the difficulty of implementing the scheme. The reactor of the present invention is insulated, and the reaction heat generated during the reaction process is removed by a heat exchanger between the two reactors, thereby maintaining the temperature of the material stable, and then the material is mixed with the next batch of propylene oxide and enters the next reactor.

[0017] In some embodiments of the present invention, the inner diameter of the inner tube of the reactor is 5-50mm, specifically, the inner diameter of the inner tube can be 5-20mm, 20-50mm, typically but not limitatively, for example, 5mm, 20mm, 50mm; the tube length is 3-20m, specifically, the tube length can be 3-12m, 12-20m, typically but not limitatively, for example, 3m, 12m, 20m.

[0018] In some embodiments of the present invention, a mixer is provided between the heat exchanger and the reactor, and the mixer is connected to the heat exchanger and the reactor, and the mixer 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. Specifically, when the reaction device 2 includes three reaction units, the reaction device 2 includes a heat exchanger 1, a mixer 1, a reactor 1, a heat exchanger 2, a mixer 2, a reactor 2, a heat exchanger 3, a mixer 3 and a reactor 3 connected in sequence, and the heat exchanger 1 is connected to the pre-reaction tank 1, and the raw materials mixed in the pre-reaction tank 1 flow into the heat exchanger 1, and are heated to the reaction temperature, and then enter the mixer 1, and after being mixed with the first batch of the second part of propylene oxide, they enter the reactor 1 together for reaction, and the reacted materials are transferred to the heat exchanger 1. Heat exchanger 2, after heat exchange in heat exchanger 2 to the reaction temperature, enters mixer 2, then mixes with the next batch of the second part of propylene oxide, and enters reactor 2 for reaction. The reacted material is transferred to heat exchanger 3, and after heat exchange in heat exchanger 3 to the reaction temperature, enters mixer 3, then mixes with the next batch of the second part of propylene oxide, and enters reactor 3 for reaction, and then flows into storage tank 3, and further flows to distillation device 4 for distillation to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively. In the present application, reaction device 2 can be operated 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 material can be added at the beginning of the reaction, or they can be added after the material flow passes through the reactor. The above-mentioned storage tank 3 is used to temporarily store the reaction product of the reaction unit and flow to the distillation device 4 for distillation.

[0019] The second aspect of the present invention is to provide a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, the production method comprising the following steps: (1) dividing propylene oxide into a first propylene oxide part and a second propylene oxide part, mixing n-butanol, potassium butoxide, a catalyst, and the first propylene oxide part, and preheating to obtain a mixture; the catalyst comprises an ether catalyst and a quaternary ammonium base catalyst; (2) dividing the second portion of propylene oxide into a plurality of batches; (3) exchanging heat of the mixture to a reaction temperature and reacting the mixture with a first batch of the second part of propylene oxide in a first reactor; (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 distill to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively.

[0020] In some embodiments of the present invention, the catalyst in step (1) includes an ether catalyst and a quaternary ammonium base catalyst; the catalyst is composed of an ether catalyst and a quaternary ammonium base catalyst in 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 limiting, for example, 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 polymer 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 does not specifically limit the source of the crown ether, and a commercially available product of the crown ether commonly used in the art can be used. The present invention does not specifically limit the source of the tetrabutylammonium hydroxide, and a commercially available product of the tetrabutylammonium hydroxide commonly used in the art can be used.

[0021] Among the above catalysts, the crown ether catalyst can enhance the attacking ability of potassium butoxide by complexing the potassium ions in 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 of the ring-opening process of the epoxy raw material. The synergistic use of the two catalysts can significantly reduce the temperature and reaction rate required for the reaction.

[0022] In order to suppress the substitution of potassium butoxide to propylene oxide by replacing it on No. 2 C to obtain isomers, the present invention adopts a method 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 back-mixing characteristic of the tubular reactor can significantly reduce the by-products such as dipropylene and tripropylene generated by the excessive reaction of the product propylene glycol butyl ether. At the same time, the design of batch addition of propylene oxide materials in the device further suppresses the excessive reaction of the product propylene glycol butyl ether and reduces the generation of by-products such as dipropylene glycol butyl ether. In addition, since the overall temperature of the material during the reaction is low, the pressure required for the reaction is also lower, which reduces the requirements for the pressure resistance of the equipment, and reduces the equipment cost and equipment maintenance cost.

[0023] 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 may be 300-500:2-3:0.1-0.2:300, 500-900:3-6:0.1-0.2:300; typically but not limiting, for example, 300:2:0.1:300, 500:3:0.2:300, 900:6:0.2:300.

[0024] 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 limitatively, for example, 40°C, 70°C, 90°C; the preheating time is 10-30min; specifically, the preheating time can be 10-15min, 15-30min; typically but not limitatively, for example, 10min, 15min, 30min.

[0025] In some embodiments of the present invention, the water content of n-butanol in step (1) is less than 100 ppm.

[0026] In some embodiments of the present invention, the free alkali content in potassium butoxide in step (1) is less than 50 ppm.

[0027] 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 1-9atm, and the reaction time is 15-90min. Specifically, the reaction temperature can be 90-95°C, 95-100°C, typically but not limiting, for example, 90°C, 95°C, 100°C; the reaction pressure can be 1-5atm, 5-9atm, typically but not limiting, for example, 1atm, 5atm, 9atm; the reaction time can be 15-45min, 45-70min, 70-90min; typically but not limiting, for example, 15min, 45min, 70min, 90min.

[0028] In some embodiments of the present invention, the second portion of propylene oxide added in step (2) is set to 3-5 batches.

[0029] In some embodiments of the present invention, the molar ratio of n-butanol to the second part of each batch of propylene oxide is 1:0.1-0.4. Specifically, the molar ratio may be 1:0.1-0.3, 1:0.3-0.4; typically but not limitedly, for example, 1:0.1, 1:0.3, 1:0.4.

[0030] In some embodiments of the present invention, the distillation pressure in step (5) is 0.1-0.5 atm.

[0031] In some embodiments of the present invention, the distillation in step (5) is specifically as follows: at a pressure of 0.1 atm, the reflux ratio is set to 1:1, and the fraction below 50°C is collected to recover n-butanol. After the internal temperature reaches 48°C, the reflux ratio is changed to 4:1, and the fraction below 65°C is collected and merged into the n-butanol recovery tank; after the internal temperature is higher than 70°C, the reflux ratio is changed to 1:1, and the propylene glycol butyl ether product is collected at 75-95°C; then the reflux ratio is changed to 10:1, and the fraction below 105°C is collected and merged into the propylene glycol butyl ether product collection tank; the fraction at 120-135°C, namely dipropylene glycol butyl ether, is collected; the reflux ratio is changed to 25:1, and the fraction at 145-170°C, namely tripropylene glycol butyl ether, is collected.

[0032] The present invention is further described below by way of examples, but the scope of the present invention is not limited thereto.

[0033] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. If specific conditions are not specified in the embodiment, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for all reagents or instruments, they are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any method, equipment, and material of the prior art similar or equivalent to the method, equipment, and material in the embodiments of the present invention can also be used to realize the present invention.

[0034] In the following example, 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 increased to 150°C at a rate of 10°C / min, and then increased to 300°C at a rate of 20°C / min, and the final temperature retention time is 10 min.

[0035] The gas chromatograph of the present invention is Shimadzu GC-2010.

[0036] Example Table 1 Reaction conditions of Examples 1-13 and Comparative Examples 1-3

[0037] Example 1 This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether. The process flow chart is as follows Figure 1 As shown, the following steps are included: Before the reaction begins, the free alkali content in the raw material potassium butoxide is determined. If it is less than 50 ppm, it is qualified. 37 kg of n-butanol and 336 g of potassium butoxide are mixed evenly, and 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 are added to obtain a mixture. After the mixture is mixed evenly, it is put into the pre-reaction tank 1, stirred at 70° C. for more than 25 minutes, and then kept warm for use; The mixture is pumped into heat exchanger 1 through a metering pump and heated to 95°C, then enters mixer 1 to mix with the first batch of the second part of propylene oxide and 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; the raw material metering pump is adjusted to control the usage and ratio of the first batch of the second part of n-butanol and propylene oxide, the amount of n-butanol added in reactor 1 is 6.17 kg / h, and the amount of propylene oxide added in reactor 1 is 0.97 kg / h; the mixture after the reaction is passed from reactor 1 to heat exchanger 1 The material in the heat exchanger 2 is kept at a constant temperature of 90-100°C, mixed with the second batch of the second part of propylene oxide in the mixer 2 and then enters the reactor 2, and the amount of propylene oxide added to the reactor 2 is 0.97 kg / h; the material from the reactor 2 is passed to the heat exchanger 3, and the material in the heat exchanger 3 is kept at a constant temperature of 90-110°C again, mixed with the third batch of the second part of propylene oxide in the mixer 3 and then enters the reactor 3, and the amount of propylene oxide added to the reactor 3 is 0.97 kg / h; the reaction is carried out for a total of 6 hours; The product in the reactor 3 was tested by gas chromatography, and the proportion of materials was 27.1% for butanol, 67.5% for propylene glycol butyl ether, 0.1% for isomers, 4.6% for dipropylene glycol butyl ether, and 0.4% for tripropylene glycol butyl ether. The residual propylene oxide accounted for 0.25%, and the conversion rate was 99.2%.

[0038] After the material flows out of the reactor three, it enters the storage tank 3 and cools down. The material in the storage tank 3 is pumped into the distillation device 4, and the reflux ratio is set to 1:1 at a pressure of 0.1atm, and the fraction below 50°C is collected to recover n-butanol. After the internal temperature reaches 48°C, the reflux ratio is changed to 4:1, and the fraction below 65°C is collected and merged into the n-butanol recovery tank. After the internal temperature is higher than 70°C, the reflux ratio is changed to 1:1, and the propylene glycol butyl ether product is collected at 75-95°C, and then the reflux ratio is changed to 10:1, and the fraction below 105°C is collected and merged into the propylene glycol butyl ether product collection tank. The fraction collected at 120-135°C is dipropylene glycol butyl ether. The reflux ratio is changed to 25:1, and the fraction collected at 145-170°C is tripropylene glycol butyl ether.

[0039] 17.4 kg of propylene oxide was added to the reaction to obtain 37.2 kg of propylene glycol butyl ether as the main product with a yield of 93.8%; 2.57 kg of dipropylene glycol butyl ether and 0.22 kg of tripropylene glycol butyl ether as by-products. Example 2

[0040] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: the amount of n-butanol added in Reactor 1 is 8.14 kg / h, the amount of the second part of propylene oxide added in each reactor is 1.28 kg / h, and the raw materials are added in 4.6 hours. Others are exactly the same as Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and statistically analyze the data, as shown in Tables 1 and 2. Example 3

[0041] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: the amount of n-butanol added in Reactor 1 is 4.89 kg / h, the amount of the second part of propylene oxide added in each reactor is 0.77 kg / h, and the raw materials are added in 7.6 hours. Others are exactly the same as Example 1. A gas chromatograph is used to detect the product components in Reactor 3 and statistically analyze the data, as shown in Tables 1 and 2. Example 4

[0042] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of n-butanol used is 66.6 kg, and the feed rate needs to be changed by adjusting the metering pump to make the amount of n-butanol added 11.1 kg / h. The rest is exactly the same as Example 1. A gas chromatograph is used to detect the product components in the reactor three and statistically analyze the data, as shown in Tables 1 and 2. Example 5

[0043] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from the embodiment 1 in that the amount of n-butanol used is 44.4 kg, and the feeding rate needs to be changed by adjusting the metering pump to make the amount of n-butanol added 7.4 kg / h. The rest is exactly the same as the embodiment 1, and the product components in the reactor 3 are detected and statistically analyzed using a gas chromatograph, and the data are shown in Tables 1 and 2. Example 6

[0044] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of n-butanol used is 22.2 kg, and the feeding rate needs to be changed by adjusting the metering pump to make the amount of n-butanol added 3.7 kg / h. The rest is exactly the same as Example 1, and a gas chromatograph is used to detect the product components in the reactor three and statistically analyze the data, as shown in Tables 1 and 2. Example 7

[0045] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of potassium butoxide used is 672 g, and the other aspects are exactly the same as Example 1. A gas chromatograph is used to detect the product components in the reactor three and statistically calculate the data, as shown in Tables 1 and 2. Example 8

[0046] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of potassium butoxide used is 224 g, and the other components are exactly the same as Example 1. A gas chromatograph is used to detect the product components in the reactor three and statistically calculate the data, as shown in Tables 1 and 2. Example 9

[0047] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of potassium butoxide used is 112 g, and the other components are exactly the same as Example 1. A gas chromatograph is used to detect the product components in the reactor three and statistically calculate the data, as shown in Tables 1 and 2. Example 10

[0048] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of catalyst 18 crown ether 6 used is 26.4 g, and the rest is exactly the same as Example 1. A gas chromatograph is used to detect the product components in reactor three and statistically calculate the data, as shown in Tables 1 and 2. Embodiment 11

[0049] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of catalyst 18 crown ether 6 used is 6.6 g, and the other components are exactly the same as Example 1. A gas chromatograph is used to detect the product components in reactor three and statistically calculate the data, as shown in Tables 1 and 2. Example 12

[0050] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of catalyst tetrabutylammonium hydroxide used is 26.0 g, and the other components are exactly the same as Example 1. A gas chromatograph is used to detect the product components in the reactor three and statistically calculate the data, as shown in Tables 1 and 2. Embodiment 13

[0051] This embodiment provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that the amount of catalyst tetrabutylammonium hydroxide used is 6.5 g, and the other components are exactly the same as Example 1. A gas chromatograph is used to detect the product components in the reactor three and statistically calculate the data, as shown in Tables 1 and 2.

[0052] Comparative Example 1 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 scheme as Example 1 is used for feeding, and the heat exchange cycle of heat exchanger 2 and heat exchanger 3 is closed, so that the reaction material is no longer subject to other temperature control after being heated by heat exchanger 1. That is, after the material is heated by heat exchanger 1, it is transferred to reactor 1 to react with the first batch of the second part of propylene oxide, and the reacted material is transferred to reactor 2 to react with the second batch of the second part of propylene oxide, and then transferred to reactor 3 to react with the third batch of the second part of propylene oxide. The rest is exactly the same as Example 1, and a gas chromatograph is used to detect the product components in reactor 3 and statistically analyze the data.

[0053] Comparative Example 2 This comparative example provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: according to the same scheme as Example 1, the amount of catalyst 18 crown ether 6 is changed to 0g, that is, catalyst 18 crown ether 6 is not used, and only catalyst tetrabutylammonium hydroxide is used as a catalyst for the reaction. In addition, heat exchanger 1, heat exchanger 2, and heat exchanger 3 are adjusted so that the temperature of the material after heat exchange during the reaction is 105°C, and the reaction temperature is maintained at 100-110°C. The rest is exactly the same as Example 1, and a gas chromatograph is used to detect the product components in reactor 3 and statistical data.

[0054] Comparative Example 3 This comparative example provides a method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, which is different from Example 1 in that: according to the same scheme as Example 1, the amount of the catalyst tetrabutylammonium hydroxide is changed to 0g, that is, the catalyst tetrabutylammonium hydroxide is not used, and only the catalyst 18 crown ether 6 is used to catalyze the reaction. In addition, heat exchanger 1, heat exchanger 2, and heat exchanger 3 are adjusted so that the temperature of the material after heat exchange during the reaction is 115°C, and the reaction temperature is maintained at 110-120°C. The rest is exactly the same as Example 1, and a gas chromatograph is used to detect the product components in reactor 3 and statistical data are obtained.

[0055] Table 2 Product components in reactor 3 in Examples 1-13 and Comparative Examples 1-3

[0056] In combination with Examples 1-3 and the data in Table 2, it can be seen that the content of dipropylene glycol butyl ether and tripropylene glycol butyl ether in Example 3 is increased compared with Example 1 and Example 2. The difference between Example 3 and Example 1 is that the material reaction time of Example 1 is 6 hours, and the reaction time of Example 3 is 7.6 hours. When the reaction time of the material is extended, the selectivity of the reaction is affected. When the reaction time is extended, the amount of dipropylene glycol butyl ether and tripropylene glycol butyl ether generated increases. When the reaction time is reduced, the raw material propylene oxide may face the problem of insufficient reaction.

[0057] In combination with Example 1, Examples 4-6, and the data in Table 2, it can be seen that after the reaction in Example 6, the production amounts of dipropylene glycol butyl ether and tripropylene glycol butyl ether are relatively large, and after the reaction in Example 4, more butanol is unreacted. The amount of butanol added affects the selectivity of the reaction. When the amount of butanol is too low, the contents of 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, but too much butanol added may affect the energy consumption of recovering butanol.

[0058] In combination with Example 1, Examples 7-9, and in combination with the data in Table 2, it can be seen that the addition of potassium butoxide has a greater effect on the reaction activity. When the amount of potassium butoxide is not less than 0.004eq of butanol, the reaction can maintain a propylene oxide conversion rate of more than 97%, that is, in Example 7 and Example 8, when the potassium butoxide content is not less than 1.2%, the amount of propylene glycol butyl ether isomers generated increases, and an appropriate amount of potassium butoxide helps to improve the reaction activity and improve the propylene oxide conversion rate.

[0059] Combining Example 1, Examples 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 amount of propylene glycol butyl ether isomers generated is slightly increased, and when the amount of crown ether catalyst is reduced in Example 11, the reaction activity and propylene oxide conversion rate are significantly reduced.

[0060] Combining Example 1, Examples 12-13, and the data in Table 2, it can be seen that in Example 12, when an excess of quaternary ammonium base is added, the amount of propylene glycol butyl ether isomers generated is significantly increased, and in Example 11, when a less amount of quaternary ammonium base is added, the reaction activity and propylene oxide conversion rate are significantly reduced.

[0061] Combining Example 1 and Comparative Example 1, and combining the data in Table 2, it can be seen that the propylene oxide conversion rate of Comparative Example 1 is low and the reaction selectivity is low. The difference between Comparative Example 1 and Example 1 is that: Comparative Example 1 closes heat exchanger 2 and heat exchanger 3, and the material temperature is low at first and high at the end of the reaction process, resulting in a low propylene oxide conversion rate. At the same time, the reaction selectivity is affected, and the reaction selectivity is low.

[0062] Combining Example 1 and Comparative Example 2, and combining the data in Table 2, it can be seen that the conversion rate of propylene oxide in the reaction of Comparative Example 2 is low, and various by-products, especially isomers, increase significantly. The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 only uses tetrabutylammonium hydroxide to catalyze the reaction, and the reaction temperature is changed to 100-110°C. When only tetrabutylammonium hydroxide is used as a catalyst for the reaction, the reaction activity is low and the selectivity is poor.

[0063] Combining Example 1 and Comparative Example 3, and combining the data in Table 2, it can be seen that the conversion rate of propylene oxide in the reaction of Comparative Example 3 is lower than 90%, and the amount of dipropylene glycol butyl ether and tripropylene glycol butyl ether generated is large. The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 only uses 18-crown ether 6 to catalyze the reaction, the reaction activity is low, and the reaction selectivity is poor.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A production system for propylene glycol butyl ether and dipropylene glycol butyl ether, characterized in that: The production system 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 to obtain n-butanol, propylene glycol butyl ether, dipropylene glycol butyl ether and tripropylene glycol butyl ether respectively.

2. The production system of propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 1, characterized in that: The number of reaction units is more than two.

3. The production system of 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.

4. The production system of 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.

5. A method for producing propylene glycol butyl ether and dipropylene glycol butyl ether, characterized in that: The production method comprises the following steps: (1) dividing propylene oxide into a first propylene oxide part and a second propylene oxide part, mixing n-butanol, potassium butoxide, a catalyst, and the first propylene oxide part, and preheating to obtain a mixture; the catalyst comprises an ether catalyst and a quaternary ammonium base catalyst; (2) dividing the second portion of propylene oxide into a plurality of batches; (3) exchanging heat of the mixture to a reaction temperature and reacting the mixture with a first batch of the second part of propylene oxide in a first reactor; (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.

6. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 5, 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.

7. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 5, characterized in that: The step (1) further includes one or more of the following features: 15) The catalyst is composed of an ether catalyst and a quaternary ammonium base catalyst in a mass ratio of 1-4:1-4; 16) The ether catalyst is selected from one or more of crown ethers, ethylene glycol ethers, diethylene glycol ethers, and polymer polyethers; 17) The quaternary ammonium base catalyst is selected from one or more of tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, and dodecyltrimethylammonium hydroxide.

8. The method for producing propylene glycol butyl ether and dipropylene glycol butyl ether according to claim 5, characterized in that: The reaction temperature in step (3) is 90-100° C., the reaction pressure is 1-9 atm, and the reaction time is 15-90 min.

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

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

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