Continuous production method of chloromethyl ethyl ether

Abstract

The invention provides a continuous production method of chloromethyl ethyl ether, and relates to the field of chloromethyl ethyl ether. The continuous production method of the chloromethyl ethyl ether comprises the following steps: depolymerization, first-stage gas-liquid reaction, second-stage microchannel reaction and third-stage pipeline reaction. The continuous production method of chloromethyl ethyl ether effectively avoids the defects of low hydrogen chloride throughput, long reaction time and low production efficiency in the batch-type reaction process, and overcomes the problems of low mass transfer efficiency, low reaction speed and high production energy consumption of heterogeneous reaction of paraformaldehyde, ethanol and hydrogen chloride gas; and on the basis of realizing continuous production of the chloromethyl ethyl ether, the purity and the yield of the continuously prepared chloromethyl ethyl ether are further improved.

Description

Technical Field

[0001] The invention relates to the field of chloromethyl ethyl ether, in particular to a continuous production method of chloromethyl ethyl ether. Background Art

[0002] Chloromethyl ether is an important organic synthesis intermediate, and is mainly used in the field of pesticides for the synthesis of insecticides, chlorpyrifos and herbicides, acetochlor. In the prior art, paraformaldehyde and anhydrous ethanol are usually mixed, and hydrogen chloride gas is introduced to react to obtain chloromethyl ether, and hydrochloric acid is produced as a byproduct. However, the current industry uses a kettle-type intermittent reaction process, and in the intermittent reaction process, in order to control the heat of reaction, the ventilation volume of hydrogen chloride gas can only be reduced, which leads to a long reaction time and low production efficiency; at the same time, in the aforementioned reaction process, paraformaldehyde and anhydrous ethanol are mixed to form a solid-liquid mixture, and hydrogen chloride gas is continuously introduced to react, and the reaction is a gas-liquid-solid multiphase reaction, and the mass transfer efficiency is low. Restricted by the mass transfer efficiency, the reaction speed is slow (the reaction time is generally 24-30h), and the production energy consumption is high; and the content of the final product (i.e., chloromethyl ether) obtained is low, and the content is generally 85-90wt%, which seriously affects the downstream application of the product.

[0003] Chinese patent CN102417440B discloses a novel synthesis process of chloromethyl ethyl ether, an intermediate of acetochlor, which passes hydrogen chloride gas into an etherification reaction kettle containing paraformaldehyde and ethanol, and controls the reaction temperature to be lower than 70°C by the rate of passing hydrogen chloride gas, performs intermittent reaction, and obtains chloromethyl ethyl ether; Chinese patent CN101302144A discloses a synthesis method and device of chloromethyl ethyl ether, an intermediate of acetochlor, which passes hydrogen chloride gas into an etherification reaction kettle containing paraformaldehyde and ethanol, performs etherification reaction, and sprays the hydrogen chloride gas escaped in the process back into the reaction kettle to continue to participate in the reaction. However, the aforementioned preparation method of chloromethyl ethyl ether, in addition to the aforementioned defects of long reaction time, low production efficiency, gas-liquid-solid multiphase reaction limiting mass transfer, and low content of final product, also has the problem that paraformaldehyde is easy to block material pipelines, and production and maintenance are difficult, and its essence is a kettle intermittent reaction process.

[0004] Thus, the defects of low hydrogen chloride ventilation volume, long reaction time and low production efficiency in the intermittent reaction process are effectively avoided, and the problems of low mass transfer efficiency, slow reaction speed and high production energy consumption in the multiphase reaction of paraformaldehyde, ethanol and hydrogen chloride gas are overcome. On the basis of realizing the continuous production of chloromethyl ether, the purity and yield of the continuously prepared chloromethyl ether are further improved, and a continuous production method of chloromethyl ether suitable for industrial-scale production is provided, which has important technical significance and research value. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a continuous production method of chloromethyl ether, which effectively avoids the defects of low hydrogen chloride ventilation volume, long reaction time and low production efficiency in an intermittent reaction process, overcomes the problems of low mass transfer efficiency, slow reaction speed and high production energy consumption in a multiphase reaction of paraformaldehyde, ethanol and hydrogen chloride gas, and further improves the purity and yield of the continuously prepared chloromethyl ether on the basis of realizing the continuous production of chloromethyl ether.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A continuous production method of chloromethyl ether consists of the following steps: depolymerization, primary gas-liquid reaction, secondary microchannel reaction, and tertiary pipeline reaction.

[0007] The method of the primary gas-liquid reaction is to introduce the depolymerization liquid and the hydrogen chloride gas into the gas-liquid reactor at the same time, control the reaction temperature to be 40-80°C, the material residence time to be 2-60s, continue the primary gas-liquid reaction, obtain the primary gas-liquid reactant, and continuously introduce it into the microchannel reactor; The depolymerization liquid is prepared by depolymerization using paraformaldehyde and anhydrous ethanol as raw materials; the formaldehyde content in the depolymerization liquid is 35-45wt%; The method of the secondary microchannel reaction is that the microchannel reactor continuously receives the primary gas-liquid reactants from the gas-liquid reactor, controls the reaction temperature to be 40-60°C, the material residence time to be 10-60s, continuously performs the secondary microchannel reaction, obtains the microchannel reactants, and continuously introduces them into the pipeline reactor; The method for the three-stage pipeline reaction is that the pipeline reactor continuously receives the microchannel reaction product from the microchannel reactor, controls the reaction temperature to be 45-50° C., and the material residence time to be 120-360s, and continuously performs the three-stage pipeline reaction to obtain a pipeline reaction liquid; the pipeline reaction liquid is subjected to internal sedimentation and stratification to obtain chloromethyl ether.

[0008] Preferably, in the primary gas-liquid reaction, the rate at which the depolymerization liquid is introduced into the gas-liquid reactor (1) is controlled to be 3-10 L / min; The molar ratio of formaldehyde to hydrogen chloride gas in the depolymerization liquid introduced into the gas-liquid reactor (1) per unit time is 1:1-3.

[0009] Furthermore, the depolymerization method is to put anhydrous ethanol, polyformaldehyde and a catalyst into a depolymerization kettle, and in a nitrogen environment, at a reaction temperature of 100-120° C. and a reaction pressure of 0.2-0.3 MPa, carry out heat preservation and depolymerization, and then filter to obtain a depolymerization liquid; and the filter cake is repeatedly reused as a catalyst.

[0010] Preferably, during the depolymerization, the time of heating to 100-120° C. does not exceed 1 h; The heat preservation and depolymerization time is 50-70 minutes.

[0011] Preferably, in the depolymerization, the weight ratio of paraformaldehyde to anhydrous ethanol is 1:1.2-1.8.

[0012] Further, in the depolymerization, the catalyst is at least one of the following: calcium oxide, magnesium oxide, magnesium hydroxide, and a composite catalyst; The amount of catalyst added is 0.3-1% by weight of the paraformaldehyde.

[0013] Furthermore, the preparation method of the composite catalyst is as follows: calcium oxide and magnesium hydroxide are added into deionized water, stirred evenly, heated to 35-40°C, zinc gluconate is added, ultrasonic treatment is performed, the mixture is placed in a closed environment, heated to 105-115°C, and after heat preservation and hydrothermal treatment, solid matter is obtained by centrifugation, and the solid matter is washed and dried, and then calcined at 190-200°C to obtain the composite catalyst.

[0014] Preferably, in the preparation of the composite catalyst, the weight ratio of calcium oxide, magnesium hydroxide, deionized water and zinc gluconate is 10-10.5:20-21:60-65:11-12.

[0015] Preferably, in the preparation of the composite catalyst, the ultrasonic frequency of the ultrasonic treatment is 22-25 kHz, the ultrasonic power is 400-500 W, and the ultrasonic treatment time is 20-30 min.

[0016] Preferably, in the preparation of the composite catalyst, the heating rate to 105-115°C is 0.8-1°C / min; The time of heat preservation water heat treatment is 50-60min; The calcination time at 190-200°C is 60-80 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The continuous production method of chloromethyl ether of the present invention adopts the depolymerization liquid of paraformaldehyde and hydrogen chloride to feed into a gas-liquid reactor at the same time under the premise of being adapted to industrial-scale production, and continuously performs a first-stage gas-liquid mixed reaction to obtain a first-stage gas-liquid reactant; then the first-stage gas-liquid reactant is fed into a microchannel reactor to continuously perform a second-stage deep reaction to obtain a microchannel reactant; then the microchannel reactant is fed into a pipeline reactor to continuously perform a delayed reaction to further promote the depth of reaction and ensure the complete progress of the reaction; the aforementioned technical means cooperate with each other and work synergistically, which can effectively avoid the defects of low hydrogen chloride ventilation volume, long reaction time and low production efficiency in the intermittent reaction process, and overcome the problems of low mass transfer efficiency, slow reaction speed and high production energy consumption in the multiphase reaction of paraformaldehyde, ethanol and hydrogen chloride gas, and further improve the purity and yield of the continuously prepared chloromethyl ether on the basis of realizing the continuous production of chloromethyl ether.

[0018] (2) In the continuous production method of chloromethyl ether of the present invention, a specific catalyst is used in the depolymerization process of paraformaldehyde, the catalyst catalyzes the depolymerization at a fast speed, and the depolymerization of paraformaldehyde is complete; the catalyst is easy to separate and recover, and a clear and transparent depolymerization liquid can be obtained by simple filtration, and the catalyst (filter cake) can be repeatedly used without post-treatment, so the production cost is low, the production efficiency is high, and the atom economy is good.

[0019] (3) The continuous production method of chloromethyl ether of the present invention aims at the problem that the feed gas-liquid volume ratio of the depolymerization liquid and the hydrogen chloride gas per unit time is too large, the conventional tubular reaction process or the microchannel reaction process cannot be used for continuous reaction, the mixed mass transfer efficiency between gas and liquid is low, the reaction efficiency is not high, and it is not suitable for industrial-scale production. The depolymerization liquid of a specific specification is combined with a primary gas-liquid reaction, a secondary microchannel reaction, and a tertiary pipeline reaction to effectively solve the above-mentioned technical problems, and the gas-liquid mass transfer efficiency is high, the reaction efficiency is high, the equipment investment is low, and it is conducive to industrial-scale production; on the basis of realizing the continuous production of chloromethyl ether, the gas chromatographic purity of the obtained product chloromethyl ether is ≥95%, the yield is ≥94%, and the daily output exceeds 7.5 tons. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a schematic diagram of a device used in the continuous production method of chloromethyl ether.

[0021] In the figure, 1-gas-liquid reactor; 2-microchannel reactor; 3-pipeline reactor. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0023] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] The embodiment of the present invention provides a continuous production method of chloromethyl ether, which comprises the following steps: depolymerization, primary gas-liquid reaction, secondary microchannel reaction, and tertiary pipeline reaction.

[0026] The depolymerization method comprises the following steps: pumping anhydrous ethanol into a depolymerization kettle, starting the stirring of the depolymerization kettle, opening a polyformaldehyde discharge port, feeding the polyformaldehyde into the depolymerization kettle, continuously feeding a catalyst, and closing a feeding valve; opening a nitrogen inlet valve and an exhaust valve of the depolymerization kettle, passing nitrogen for 10 minutes to replace the air in the depolymerization kettle, adjusting the pressure in the depolymerization kettle to 0.2-0.3 MPa, closing the nitrogen inlet valve and the exhaust valve, controlling the depolymerization kettle to heat up to 100-120° C. within 1 hour, stirring and reacting for 50-70 minutes under the conditions of a reaction temperature of 100-120° C. and a reaction pressure of 0.2-0.3 MPa, cooling the temperature to 30° C., filtering, and feeding a filtrate (i.e., a depolymerization liquid with a formaldehyde content of 35-45 wt%) into a depolymerization liquid transfer tank for standby use; and recycling the filter cake (catalyst) into the depolymerization kettle as a catalyst.

[0027] In the depolymerization, the weight ratio of paraformaldehyde to anhydrous ethanol is 1:1.2-1.8, preferably 1:1.5-1.6.

[0028] The catalyst is at least one of the following: calcium oxide, magnesium oxide, magnesium hydroxide, and a composite catalyst; the added amount of the catalyst is 0.3-1% of the weight of the polyformaldehyde.

[0029] The particle size of the catalyst is 80-120 mesh.

[0030] In the depolymerization process of paraformaldehyde, the catalytic depolymerization speed is fast under the catalytic action of a specific catalyst, and the separation and recovery are easy. A clear and transparent depolymerization liquid can be obtained by simple filtration, and the catalyst (filter cake) can be repeatedly used without post-treatment, so the production cost is low and the production efficiency is high. The invention can effectively avoid the problem of the impurity sodium chloride generated with the depolymerization reaction in the existing paraformaldehyde depolymerization process using sodium ethoxide, on the one hand further avoiding the pipeline blockage caused by it, and on the other hand avoiding the introduction of sodium ions affecting the quality of by-product hydrochloric acid. At the same time, sodium ethoxide is difficult to recover after being dissolved in ethanol. Compared with the one-time catalysis of sodium ethoxide, the invention realizes multiple recycling of the catalyst, further reduces the production cost, improves the atomic economy, and conforms to the concept of green chemistry.

[0031] The depolymerization step of the embodiment of the present invention can also effectively overcome the problems of low depolymerization efficiency, incomplete depolymerization and difficult catalyst recovery of existing catalytic components (such as triethylamine, sulfuric acid, sodium hydroxide, and p-toluenesulfonic acid).

[0032] Furthermore, the preparation method of the composite catalyst is as follows: calcium oxide and magnesium hydroxide are added into deionized water, stirred at 80-100 rpm for 20-30 minutes, stirred and heated to 35-40°C, zinc gluconate is continuously added, the ultrasonic frequency is controlled to be 22-25 kHz, the ultrasonic power is 400-500 W, ultrasonic treatment is performed for 20-30 minutes, and then the mixture is transferred into a high-pressure reactor, the high-pressure reactor is sealed, and the temperature is increased to 105-115°C at a heating rate of 0.8-1°C / min, and the mixture is subjected to hydrothermal treatment for 50-60 minutes, and then centrifuged to obtain a solid, the solid is washed with deionized water, and then dried in a drying oven at 90-95°C, and then transferred into a calcining furnace, calcined at 190-200°C for 60-80 minutes, and cooled to obtain a zinc oxide-coated composite catalyst (calcium oxide, magnesium hydroxide), i.e., a composite catalyst.

[0033] Wherein, the weight ratio of calcium oxide, magnesium hydroxide, deionized water and zinc gluconate is 10-10.5:20-21:60-65:11-12.

[0034] In the depolymerization step of the embodiment of the present invention, when calcium oxide, magnesium oxide, magnesium hydroxide or a combination thereof is used as a catalyst, in the high-pressure depolymerization process of 0.2-0.3MPa, the catalyst is affected by multiple factors such as temperature, pressure and filtering operation. When it is recycled for multiple times, there is a pulverization situation, which will lead to a decrease in catalytic performance and an increase in the difficulty of separating the catalyst, limiting the number of effective recycling times; after testing, the above-mentioned catalyst was pulverized after 15 cycles. In the preparation of the composite catalyst, the present invention adopts calcium oxide and magnesium hydroxide as the matrix material, and adopts a composite method of in-situ coating to coat the composite catalyst (calcium oxide, magnesium hydroxide), which increases the active sites and improves the catalytic performance through the synergistic effect of zinc oxide, calcium oxide and magnesium hydroxide; and at the same time improves the structural stability of the composite catalyst, improves its anti-interference ability to external factors such as temperature and pressure, improves its recycling performance, and avoids the possible pulverization in multiple recycling; after testing, the composite catalyst prepared by it is recycled for 40 times, and the catalyst does not appear pulverization.

[0035] The method for the primary gas-liquid reaction is to introduce the depolymerization liquid and hydrogen chloride gas into the gas-liquid reactor 1 at the same time, control the introduction rate of the depolymerization liquid to be 3-10 L / min, continue the primary gas-liquid reaction, continuously obtain the primary gas-liquid reactant, and introduce it into the microchannel reactor 2.

[0036] During the primary gas-liquid reaction, the reaction temperature is controlled to be 40-80° C., and the residence time of the depolymerization liquid in the gas-liquid reactor 1 is 2-60 s.

[0037] During the primary gas-liquid reaction, the molar ratio of formaldehyde in the depolymerization liquid fed into the gas-liquid reactor 1 to the hydrogen chloride gas per unit time is 1:1-3, preferably 1:1.2-1.5.

[0038] The gas-liquid reactor 1 is a packed tower reactor, which is filled with fillers for flow disturbance to promote a full mixing reaction of gas and liquid.

[0039] The method for the secondary microchannel reaction is that the microchannel reactor 2 continuously receives the primary gas-liquid reactants from the gas-liquid reactor 1, controls the reaction temperature to be 40-60°C, and the residence time of the primary gas-liquid reactants in the microchannel reactor 2 is 10-60s, performs the secondary microchannel reaction, continuously obtains the microchannel reactants, and introduces them into the pipeline reactor 3.

[0040] The method for the three-stage pipeline reaction is as follows: the pipeline reactor 3 continuously receives the microchannel reactants from the microchannel reactor 2, the reaction temperature is controlled to be 45-50°C, the residence time of the microchannel reaction product in the pipeline reactor 3 is 120-360s, and the three-stage pipeline reaction is performed to obtain a pipeline reaction liquid, which is introduced into a receiving kettle; the pipeline reaction liquid is settled and stratified in the receiving kettle, the upper layer is the product chloromethyl ether, which is collected in a product tank; the lower layer is the waste acid liquid, which is treated with sewage.

[0041] In the three-stage pipeline reaction, the pipeline reactor 3 is a spirally wound pipeline reactor 3.

[0042] The purity of the product chloromethyl ether is ≥95%, the yield is ≥94%, and the daily output exceeds 7.5t.

[0043] The inventors found in the research and development process of continuously preparing chloromethyl ether by using a depolymerization liquid of paraformaldehyde and hydrogen chloride gas that although the use of the depolymerization liquid of paraformaldehyde does not require special control of the reaction exotherm and the ventilation volume of the hydrogen chloride gas, a large amount of hydrogen chloride is required to achieve the best reaction effect. Compared with the depolymerization liquid, the feed gas-liquid volume ratio per unit time is as high as 260-300:1. If a conventional tubular reaction process or a microchannel reaction process is used for continuous reaction, under the aforementioned large gas-liquid volume ratio condition, the mixed mass transfer efficiency between gas and liquid is low, the reaction efficiency is not high, and a multi-stage reaction module is required to cooperate, the equipment investment is high, and it is not suitable for industrial-scale production.

[0044] The continuous production method of chloromethyl ether of the present invention adopts the following steps: under the premise of being adapted to industrial-scale production, a depolymerization liquid of paraformaldehyde prepared by a specific method is fed into a gas-liquid reactor 1 simultaneously with hydrogen chloride, and a first-stage gas-liquid mixed reaction is continuously performed to obtain a first-stage gas-liquid reactant; then the first-stage gas-liquid reactant is fed into a microchannel reactor 2 to continuously perform a second-stage deep reaction to obtain a microchannel reactant; then the microchannel reactant is fed into a pipeline reactor 3 to continuously perform a delayed reaction, so as to further promote the reaction depth, ensure that the reaction is completely performed, and further improve the purity and yield of the continuously prepared chloromethyl ether.

[0045] The continuous production method of chloromethyl ether of the present invention has various technical means that cooperate with each other and work synergistically, and can effectively avoid the defects of low hydrogen chloride ventilation volume, long reaction time and low production efficiency in an intermittent reaction process, and overcome the problems of low mass transfer efficiency, slow reaction speed and high production energy consumption in a multiphase reaction of paraformaldehyde, ethanol and hydrogen chloride gas. On the basis of realizing the continuous production of chloromethyl ether, the purity and yield of the continuously prepared chloromethyl ether are further improved.

[0046] The present invention is further described below in conjunction with some specific embodiments.

[0047] Example 1 In the continuous production method of chloromethyl ether, the specific operation of the depolymerization step is: 1540 kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, and after 1000 kg of polyformaldehyde was added into the depolymerization kettle, 3 kg of calcium oxide (catalyst) was continuously added, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.3 MPa, and the nitrogen inlet valve and the exhaust valve were closed, and the temperature of the depolymerization kettle was controlled to rise to 100° C. within 1 hour, and after stirring and reacting for 60 minutes, the temperature was lowered to 30° C. and filtered, and the filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 39.37 wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0048] Among them, the particle size specification of calcium oxide is 100 mesh.

[0049] After testing, it was found that calcium oxide was used as a catalyst and after being recycled 15 times, the catalyst began to powder.

[0050] Example 2 The specific operation of the depolymerization step in the continuous production method of chloromethyl ether is: 1540 kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, and after 1000 kg of polyformaldehyde was added into the depolymerization kettle, 10 kg of magnesium oxide (catalyst) was continuously added, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed through for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.3 MPa, and the nitrogen inlet valve and the exhaust valve were closed, and the temperature of the depolymerization kettle was controlled to rise to 100° C. within 1 hour, and after stirring and reacting for 60 minutes, the temperature was lowered to 30° C. and filtered, and the filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 39.37 wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0051] Among them, the particle size specification of magnesium oxide is 100 mesh.

[0052] After testing, it was found that when magnesium oxide was used as a catalyst, the catalyst began to powder after being recycled 15 times.

[0053] Example 3 The specific operation of the depolymerization step in the continuous production method of chloromethyl ether is: 2400 kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, 1500 kg of polyformaldehyde was added into the depolymerization kettle, and then 7.5 kg of magnesium hydroxide (catalyst) was added, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed through for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.3 MPa, and the nitrogen inlet valve and the exhaust valve were closed. The depolymerization kettle was controlled to heat up to 100° C. within 1 hour, and after stirring and reacting for 60 minutes, the temperature was lowered to 30° C. and filtered. The filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 38.46 wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0054] Wherein, the particle size specification of magnesium hydroxide is 100 mesh.

[0055] After testing, it was found that when magnesium hydroxide was used as a catalyst and recycled 15 times, the catalyst began to powder.

[0056] Example 4 The specific operation of the depolymerization step in the continuous production method of chloromethyl ether is: 2400kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, and after 1500kg of polyformaldehyde was added into the depolymerization kettle, 5kg of catalyst compounded with calcium oxide and magnesium hydroxide was continuously added, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed through for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.3MPa, and the nitrogen inlet valve and the exhaust valve were closed, and the temperature of the depolymerization kettle was controlled to rise to 100°C within 1 hour, and after stirring and reacting for 60 minutes, the temperature was lowered to 30°C, filtered, and the filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 38.46wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0057] The composite catalyst is composed of calcium oxide and magnesium hydroxide; the weight ratio of calcium oxide to magnesium hydroxide is 1:2.

[0058] The particle size specification of calcium oxide is 100 mesh; the particle size specification of magnesium hydroxide is 100 mesh.

[0059] Example 5 The specific operation of the depolymerization step in the continuous production method of chloromethyl ether is: 2310 kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, 1500 kg of polyformaldehyde was added into the depolymerization kettle, and then 3 kg of composite catalyst was added, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.2 MPa, and the nitrogen inlet valve and the exhaust valve were closed, and the temperature of the depolymerization kettle was controlled to rise to 100° C. within 1 hour, and after stirring and reacting for 50 minutes, the temperature was lowered to 30° C. and filtered, and the filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 39.37 wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0060] The preparation method of the composite catalyst is as follows: calcium oxide and magnesium hydroxide are added into deionized water, stirred at 90 rpm for 25 minutes, then heated to 35°C with stirring, zinc gluconate is added, the ultrasonic frequency is controlled to be 22 kHz, the ultrasonic power is 450 W, ultrasonic treatment is performed for 30 minutes, and then the mixture is transferred into a high-pressure reactor, the high-pressure reactor is sealed, and the mixture is heated to 110°C at a heating rate of 0.8°C / min, and heat-treated with water for 50 minutes, and then solids are obtained by centrifugation. After the solids are washed with deionized water, they are placed in a drying oven at 90°C for drying, and then transferred into a calcining furnace, calcined at 200°C for 70 minutes, cooled, and ground evenly to obtain a zinc oxide-coated composite catalyst (calcium oxide, magnesium hydroxide), i.e., a composite catalyst.

[0061] Among them, the weight ratio of calcium oxide, magnesium hydroxide, deionized water and zinc gluconate is 10.2:20.5:63:11.6.

[0062] After testing, the prepared composite catalyst did not show any powdering after being recycled 40 times; while improving the catalytic efficiency, it was able to improve its resistance to interference from external factors such as temperature and pressure, improve its recycling performance, avoid possible powdering during multiple recycling, and the effective recycling times exceeded 40 times.

[0063] Example 6 The specific operation of the depolymerization step in the continuous production method of chloromethyl ether is: 2400 kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, 1500 kg of polyformaldehyde was added into the depolymerization kettle, and then 3 kg of composite catalyst was added, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed through for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.3 MPa, and the nitrogen inlet valve and the exhaust valve were closed, and the temperature of the depolymerization kettle was controlled to rise to 100° C. within 1 hour, and after stirring and reacting for 50 minutes, the temperature was lowered to 30° C. and filtered, and the filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 38.46 wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0064] The preparation method of the composite catalyst is as follows: calcium oxide and magnesium hydroxide are added into deionized water, stirred at 100 rpm for 30 minutes, then heated to 40°C with stirring, zinc gluconate is added, the ultrasonic frequency is controlled to be 22 kHz, the ultrasonic power is 450 W, ultrasonic treatment is performed for 30 minutes, and then the mixture is transferred into a high-pressure reactor, the high-pressure reactor is sealed, and the temperature is increased to 115°C at a heating rate of 0.8°C / min, and the mixture is subjected to water heat treatment for 60 minutes, and then solid matter is obtained by centrifugation. After the solid matter is washed with deionized water, it is placed in a drying oven at 95°C for drying, and then transferred into a calcining furnace, calcined at 195°C for 70 minutes, cooled, and ground evenly to obtain a zinc oxide-coated composite catalyst (calcium oxide, magnesium hydroxide), i.e., a composite catalyst.

[0065] Among them, the weight ratio of calcium oxide, magnesium hydroxide, deionized water and zinc gluconate is 10.5:21:65:12.

[0066] After testing, the prepared composite catalyst did not show any powdering after being recycled 40 times; while improving the catalytic efficiency, it was able to improve its resistance to interference from external factors such as temperature and pressure, improve its recycling performance, avoid possible powdering during multiple recycling, and the effective recycling times exceeded 40 times.

[0067] Example 7 Example 7 is a blank control scheme of Example 1, except that no catalyst is used; specifically: 1540 kg of anhydrous ethanol was pumped into the depolymerization kettle, the stirring of the depolymerization kettle was started, the polyformaldehyde discharge port was opened, 1000 kg of polyformaldehyde was added into the depolymerization kettle, and the feed valve was closed; the nitrogen inlet valve and the exhaust valve of the depolymerization kettle were opened, and nitrogen was passed for 10 minutes to replace the air in the depolymerization kettle, and the pressure in the depolymerization kettle was adjusted to 0.3 MPa, and the nitrogen inlet valve and the exhaust valve were closed. The depolymerization kettle was controlled to heat up to 100° C. within 1 hour, and after stirring and reacting for 60 minutes, the temperature was lowered to 30° C. and filtered. The filtrate (i.e., the depolymerization liquid, with a formaldehyde content of 20.04 wt%) was put into the depolymerization liquid transfer tank for standby use; the filter cake (catalyst) was continuously reused as a catalyst into the depolymerization kettle.

[0068] The relevant process parameters and depolymerization results in the above Examples 1-7 are shown in the following table:

[0069] Example 8 This embodiment provides a continuous production method of chloromethyl ether, which consists of the following steps: depolymerization, primary gas-liquid reaction, secondary microchannel reaction, and tertiary pipeline reaction.

[0070] 1. Depolymerization The depolymerization step of this example is carried out according to the technical scheme of Example 5 to prepare a depolymerization liquid with a formaldehyde content of 39.37 wt %.

[0071] 2. Primary gas-liquid reaction The depolymerization liquid and hydrogen chloride gas are introduced into the gas-liquid reactor 1 at the same time, and the introduction rate of the depolymerization liquid is controlled to be 5L / min. The primary gas-liquid reaction is continuously carried out, and the primary gas-liquid reactant is continuously obtained and introduced into the microchannel reactor 2.

[0072] In the primary gas-liquid reaction process, the reaction temperature was controlled to be 40° C., and the residence time of the depolymerization liquid in the gas-liquid reactor 1 was 2 s.

[0073] During the primary gas-liquid reaction, the molar ratio of formaldehyde in the depolymerization liquid fed into the gas-liquid reactor 1 to the hydrogen chloride gas per unit time is 1:1.25.

[0074] The gas-liquid reactor 1 is a packed tower reactor, which is filled with fillers for flow disturbance to promote a full mixing reaction of gas and liquid.

[0075] 2. Secondary microchannel reaction Microchannel reactor 2 continuously receives primary gas-liquid reactants from gas-liquid reactor 1, controls the reaction temperature to 45°C, and the residence time of primary gas-liquid reactants in microchannel reactor 2 is 10s. Secondary microchannel reaction is carried out, microchannel reactants are continuously obtained, and introduced into pipeline reactor 3.

[0076] 3. Three-stage pipeline reaction The pipeline reactor 3 continuously receives the microchannel reaction product from the microchannel reactor 2, controls the reaction temperature to be 45°C, and the residence time of the microchannel reaction product in the pipeline reactor 3 is 360s. A three-stage pipeline reaction is performed to obtain a pipeline reaction liquid, which is introduced into the receiving kettle; the pipeline reaction liquid is settled and stratified in the receiving kettle, and the upper layer is the product chloromethyl ether, which is collected in the product tank; the lower layer is the waste acid liquid, which is treated with sewage.

[0077] Wherein, the pipeline reactor 3 is a spirally wound pipeline reactor 3.

[0078] The gas chromatographic purity of the product chloromethyl ether is 95.2%, and the yield is 94.1%.

[0079] like Figure 1 As shown, the continuous production device of chloromethyl ether used in this embodiment includes: a gas-liquid reactor 1, a microchannel reactor 2, and a pipeline reactor 3.

[0080] The feed port of the gas-liquid reactor 1 is connected to the hydrogen chloride gas and the depolymerization liquid feed pipelines respectively, so that the depolymerization liquid and hydrogen chloride are simultaneously fed into the gas-liquid reactor 1 for primary gas-liquid reaction.

[0081] The discharge port of the gas-liquid reactor 1 is connected to the feed port of the microchannel reactor 2, so that the primary gas-liquid reactants of the gas-liquid reactor 1 are fed into the microchannel reactor 2 for secondary microchannel reaction.

[0082] The discharge port of the microchannel reactor 2 is connected to the feed port of the pipeline reactor 3 so that the microchannel reaction product of the microchannel reactor 2 is fed into the pipeline reactor 3 to perform a tertiary pipeline reaction.

[0083] The discharge port of the pipeline reactor 3 is connected to the feed port pipeline of the receiving kettle, so that the pipeline reaction liquid of the pipeline reactor 3 is settled and stratified in the receiving kettle, and the product chloromethyl ether is collected.

[0084] Example 9 This embodiment provides a continuous production method of chloromethyl ether, which consists of the following steps: depolymerization, primary gas-liquid reaction, secondary microchannel reaction, and tertiary pipeline reaction.

[0085] 1. Depolymerization The depolymerization step of this example is carried out according to the technical scheme of Example 6 to prepare a depolymerization liquid with a formaldehyde content of 38.46 wt %.

[0086] 2. Primary gas-liquid reaction The depolymerization liquid and hydrogen chloride gas are introduced into the gas-liquid reactor 1 at the same time, and the introduction rate of the depolymerization liquid is controlled to be 8 L / min. The primary gas-liquid reaction is continuously carried out, and the primary gas-liquid reactant is continuously obtained and introduced into the microchannel reactor 2.

[0087] In the first-stage gas-liquid reaction process, the reaction temperature was controlled to be 40° C., and the residence time of the depolymerization liquid in the gas-liquid reactor 1 was 5 s.

[0088] During the primary gas-liquid reaction, the molar ratio of formaldehyde in the depolymerization liquid fed into the gas-liquid reactor 1 to the hydrogen chloride gas per unit time is 1:1.3.

[0089] The gas-liquid reactor 1 is a packed tower reactor, which is filled with fillers for flow disturbance to promote a full mixing reaction of gas and liquid.

[0090] 2. Secondary microchannel reaction Microchannel reactor 2 continuously receives primary gas-liquid reactants from gas-liquid reactor 1, controls the reaction temperature to 40°C, and the residence time of primary gas-liquid reactants in microchannel reactor 2 is 30s. Secondary microchannel reaction is carried out, microchannel reactants are continuously obtained, and introduced into pipeline reactor 3.

[0091] 3. Three-stage pipeline reaction The pipeline reactor 3 continuously receives the microchannel reaction product from the microchannel reactor 2, controls the reaction temperature to be 45°C, and the residence time of the microchannel reaction product in the pipeline reactor 3 is 240s. A three-stage pipeline reaction is performed to obtain a pipeline reaction liquid, which is introduced into the receiving kettle; the pipeline reaction liquid is settled and stratified in the receiving kettle, and the upper layer is the product chloromethyl ether, which is collected in the product tank; the lower layer is the waste acid liquid, which is treated with sewage.

[0092] Wherein, the pipeline reactor 3 is a spirally wound pipeline reactor 3.

[0093] The gas chromatographic purity of the product chloromethyl ether is 95.0%, and the yield is 94.0%.

[0094] The continuous production device of chloromethyl ether used in this embodiment is the same as that in Example 8.

[0095] Example 10 This embodiment provides a continuous production method of chloromethyl ether, which consists of the following steps: depolymerization, primary gas-liquid reaction, secondary microchannel reaction, and tertiary pipeline reaction.

[0096] 1. Depolymerization The depolymerization step of this example is carried out according to the technical scheme of Example 5 to prepare a depolymerization liquid with a formaldehyde content of 39.37 wt %.

[0097] 2. Primary gas-liquid reaction The depolymerization liquid and hydrogen chloride gas are introduced into the gas-liquid reactor 1 at the same time, and the introduction rate of the depolymerization liquid is controlled to be 8 L / min. The primary gas-liquid reaction is continuously carried out, and the primary gas-liquid reactant is continuously obtained and introduced into the microchannel reactor 2.

[0098] In the first-stage gas-liquid reaction process, the reaction temperature was controlled to be 40° C., and the residence time of the depolymerization liquid in the gas-liquid reactor 1 was 5 s.

[0099] During the primary gas-liquid reaction, the molar ratio of formaldehyde in the depolymerization liquid fed into the gas-liquid reactor 1 to the hydrogen chloride gas per unit time was 1:1.28.

[0100] The gas-liquid reactor 1 is a packed tower reactor, which is filled with fillers for flow disturbance to promote a full mixing reaction of gas and liquid.

[0101] 2. Secondary microchannel reaction Microchannel reactor 2 continuously receives primary gas-liquid reactants from gas-liquid reactor 1, controls the reaction temperature to 40°C, and the residence time of primary gas-liquid reactants in microchannel reactor 2 is 30s. Secondary microchannel reaction is carried out, microchannel reactants are continuously obtained, and introduced into pipeline reactor 3.

[0102] 3. Three-stage pipeline reaction The pipeline reactor 3 continuously receives the microchannel reaction product from the microchannel reactor 2, controls the reaction temperature to be 45°C, and the residence time of the microchannel reaction product in the pipeline reactor 3 is 240s. A three-stage pipeline reaction is performed to obtain a pipeline reaction liquid, which is introduced into the receiving kettle; the pipeline reaction liquid is settled and stratified in the receiving kettle, and the upper layer is the product chloromethyl ether, which is collected in the product tank; the lower layer is the waste acid liquid, which is treated with sewage.

[0103] Wherein, the pipeline reactor 3 is a spirally wound pipeline reactor 3.

[0104] The gas chromatographic purity of the product chloromethyl ether is 95.4%, and the yield is 94.7%.

[0105] The continuous production device of chloromethyl ether used in this embodiment is the same as that in Example 8.

[0106] Comparative Example 1 Comparative Example 1 The production method of chloromethyl ether is an intermittent kettle process, specifically: 1. Add 1200kg of paraformaldehyde and 1900kg of anhydrous ethanol into a 5000L reactor and start stirring; open the cooling water inlet and outlet valves of the reactor jacket and control the temperature in the reactor at 20℃.

[0107] 2. Open the hydrogen chloride inlet valve and introduce hydrogen chloride gas into the kettle, controlling the total weight of hydrogen chloride gas introduced to 1700 kg; the chlorine feeding rate is controlled at 30 kg / h in the first 5 hours, 50 kg / h in the middle, and 30 kg / h in the last 5 hours.

[0108] 3. After the hydrogen chloride gas is introduced, continue stirring. When the liquid in the reactor changes from a slurry to a clear and transparent state, stop stirring and allow the reaction to settle and separate into layers. The upper layer is the product chloromethyl ether, with a gas chromatographic purity of 90% and a yield of 75%.

[0109] Unless otherwise specified, all percentages used in the present invention are by mass.

[0110] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous production method of chloromethyl ether, characterized in that, It consists of the following steps: depolymerization, primary gas-liquid reaction, secondary microchannel reaction, and tertiary pipeline reaction; The method for the primary gas-liquid reaction is to introduce the depolymerization liquid and the hydrogen chloride gas into the gas-liquid reactor (1) at the same time, control the reaction temperature to be 40-80°C, and the material residence time to be 2-60s, continue the primary gas-liquid reaction, obtain the primary gas-liquid reactant, and continuously introduce it into the microchannel reactor (2); The depolymerization liquid is prepared by depolymerization using paraformaldehyde and anhydrous ethanol as raw materials; the formaldehyde content in the depolymerization liquid is 35-45wt%; The method for the secondary microchannel reaction is as follows: the microchannel reactor (2) continuously receives the primary gas-liquid reactants from the gas-liquid reactor (1), controls the reaction temperature to be 40-60° C., and the material residence time to be 10-60 seconds, continuously performs the secondary microchannel reaction, obtains the microchannel reactants, and continuously introduces them into the pipeline reactor (3); The method for the three-stage pipeline reaction is as follows: the pipeline reactor (3) continuously receives the microchannel reaction product from the microchannel reactor (2), controls the reaction temperature to be 45-50° C., and the material residence time to be 120-360 seconds, and continuously performs the three-stage pipeline reaction to obtain a pipeline reaction liquid; the pipeline reaction liquid is subjected to internal sedimentation and stratification to obtain chloromethyl ethyl ether.

2. The continuous production method of chloromethyl ether according to claim 1, characterized in that: In the first-stage gas-liquid reaction, the rate of introducing the depolymerization liquid into the gas-liquid reactor (1) is controlled to be 3-10 L / min; The molar ratio of formaldehyde to hydrogen chloride gas in the depolymerization liquid introduced into the gas-liquid reactor (1) per unit time is 1:1-3.

3. The continuous production method of chloromethyl ether according to claim 1, characterized in that: The depolymerization method comprises the following steps: putting anhydrous ethanol, paraformaldehyde and a catalyst into a depolymerization kettle, performing depolymerization under heat preservation in a nitrogen environment at a reaction temperature of 100-120° C. and a reaction pressure of 0.2-0.3 MPa, and filtering to obtain a depolymerization liquid; and the filter cake is repeatedly reused as a catalyst.

4. The continuous production method of chloromethyl ether according to claim 3, characterized in that: During the depolymerization, the temperature is raised to 100-120° C. for no more than 1 hour; The heat preservation and depolymerization time is 50-70 minutes.

5. The continuous production method of chloromethyl ether according to claim 3, characterized in that: In the depolymerization, the weight ratio of paraformaldehyde to anhydrous ethanol is 1:1.2-1.

8.

6. The continuous production method of chloromethyl ether according to claim 3, characterized in that: In the depolymerization, the catalyst is at least one of the following: calcium oxide, magnesium oxide, magnesium hydroxide, and a composite catalyst; The amount of catalyst added is 0.3-1% by weight of the paraformaldehyde.

7. The continuous production method of chloromethyl ether according to claim 6, characterized in that: The preparation method of the composite catalyst comprises the following steps: adding calcium oxide and magnesium hydroxide into deionized water, stirring evenly, heating to 35-40° C., adding zinc gluconate, performing ultrasonic treatment, transferring to a closed environment, heating to 105-115° C., performing heat preservation and hydrothermal treatment, centrifuging to obtain a solid, washing and drying the solid, and then calcining at 190-200° C. to obtain the composite catalyst.

8. The continuous production method of chloromethyl ether according to claim 7, characterized in that: In the preparation of the composite catalyst, the weight ratio of calcium oxide, magnesium hydroxide, deionized water and zinc gluconate is 10-10.5:20-21:60-65:11-12.

9. The continuous production method of chloromethyl ether according to claim 7, characterized in that: In the preparation of the composite catalyst, the ultrasonic frequency of the ultrasonic treatment is 22-25 kHz, the ultrasonic power is 400-500 W, and the ultrasonic treatment time is 20-30 min.

10. The continuous production method of chloromethyl ether according to claim 7, characterized in that: In the preparation of the composite catalyst, the heating rate to 105-115°C is 0.8-1°C / min; The time of heat preservation water heat treatment is 50-60min; The calcination time at 190-200°C is 60-80 minutes.

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