Method and device for synthesizing diisopropyl hydroxylamine by microchannel reactor

Abstract

The invention discloses a method and a device for synthesizing diisopropyl hydroxylamine by a microchannel reactor. The method comprises the following steps: (1) heating diisopropanolamine until diisopropanolamine is molten; (2) respectively inputting the molten liquid diisopropanolamine and hydrogen peroxide into the microchannel reactor through a metering pump for reaction, wherein the reaction temperature and the reaction pressure are controlled by an external controller; and (3) after the reaction is finished, collecting the diisopropyl hydroxylamine aqueous solution flowing out of the microchannel reactor, cooling and recrystallizing to obtain the product diisopropyl hydroxylamine. The method provided by the invention has the advantages of few side reactions, high product selectivity and high yield; the energy consumption is low.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical industry, and in particular to a method and a device for synthesizing diisopropylhydroxylamine in a microchannel reactor. Background Art

[0002] Diisopropylhydroxylamine is an important fine chemical. It is widely used in the field of styrene polymerization inhibition due to its excellent inhibitory effect on olefins. In addition, due to its strong reducing property, it can also be used in the production of antioxidants and as a boiler descaling agent.

[0003] Chinese patent CN106957240A discloses a two-step synthesis method of hydroxypropylhydroxylamine, that is, firstly preparing hydroxylamine free base with hydroxylamine salt and alkali solution, and then adding alkylene oxide to the above hydroxylamine free base to synthesize hydroxypropylhydroxylamine. The above synthesis method has the following defects: low temperature is required to prevent the free base from decomposing, but a higher temperature is required for the reaction with propylene oxide, which will cause the loss of raw material hydroxylamine. And this type of reaction has two problems: 1) the safety problem of hydroxylamine decomposition and explosion; 2) hydroxylamine is easy to decompose, resulting in a low product yield.

[0004] U.S. Patent No. 6,028,225 discloses a method for synthesizing dihydroxypropylhydroxylamine using 50% hydroxylamine free base and propylene oxide as raw materials. This method also has the following defects: (1) the decomposition and explosion safety hazard of hydroxylamine free base; (2) the use of 50% hydroxylamine free base as raw material has the disadvantages of few suppliers and high price.

[0005] Chinese patent CN112159333A discloses an improved method, that is, propylene oxide and hydroxylamine salt are added to a solvent in advance and mixed evenly, and then alkali solution is added dropwise, so that the two-step reaction can be completed at one time, avoiding the generation and decomposition of free hydroxylamine, improving the safety of production and product yield, but the subsequent purification process still requires extraction and distillation. In addition, since inorganic bases are used in the process of preparing free hydroxylamine, the inorganic salts and water generated by the inorganic bases and hydroxylamine salts are dissolved in the solution and cannot be directly distilled and purified, so extraction and other steps are required for further processing, and the product purification steps are more, which affects the product yield and increases the production cost.

[0006] Chinese patent CN117304066A discloses a catalytic oxidation approach, in which diisopropanolamine and hydrogen peroxide are reacted as main raw materials under the action of titanium silicon molecular sieve (TS-1) catalyst. After the reaction is completed, the catalyst is separated by filtration, and unreacted raw materials and solvents are removed by vacuum distillation technology to finally obtain a high-purity diisopropanol hydroxylamine product. Environmentally friendly titanium silicon molecular sieve is used as a catalyst, which has good catalytic activity and reusability. Although the method is effective, the product yield is 48.9% to 89.67%. When TS-1 is used to catalyze the reaction of diisopropanolamine, although it shows excellent performance in some aspects, it also has the problems of high cost, excessive oxidation of diisopropanolamine to ammonium nitrate byproducts and poor stability caused by excessive activity.

[0007] Chinese patent CN117342973A discloses a method for preparing diisopropylhydroxylamine without catalyst, i.e., using anhydride and hydrogen peroxide as oxidants, mixing hydrogen peroxide solution and anhydride to obtain an oxidizing solution, then adding diisopropylamine and a solvent mixed solution for oxidation reaction, and finally extracting with an extractant and distilling under reduced pressure to obtain a dihydroxypropylhydroxylamine product with a high yield. However, the reaction of anhydride and hydrogen peroxide is usually a strong exothermic reaction, and unstable peroxides may be generated during the reaction. These peroxides have high oxidizing and explosive properties. If the reaction is not properly controlled, it may cause a rapid increase in temperature and even cause a fire or explosion.

[0008] In summary, the existing process for preparing diisopropanol hydroxylamine has many deficiencies, mainly including harsh reaction conditions, such as high temperature and the use of strong base, which leads to high equipment requirements and complex operation, and many safety hazards; more by-products are produced, resulting in poor selectivity, increasing the difficulty of separation and purification, and reducing the yield of the target product; in addition, the production cost is high, the energy consumption is large, the equipment investment is large, and the product quality is unstable. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a method and device for synthesizing diisopropylhydroxylamine in a microchannel reactor.

[0010] The technical solution adopted by the present invention is:

[0011] A method for synthesizing diisopropylhydroxylamine using a microchannel reactor comprises the following steps:

[0012] (1) heating diisopropanolamine until it melts;

[0013] (2) The melted liquid diisopropanolamine and hydrogen peroxide are respectively introduced into the microchannel reactor through metering pumps for reaction, and the reaction temperature and reaction pressure are controlled by an external controller.

[0014] (3) After the reaction is completed, the diisopropylhydroxylamine aqueous solution flowing out of the microchannel reactor is collected, cooled and recrystallized to obtain the product diisopropylhydroxylamine.

[0015] Furthermore, in step (1), the heating temperature of diisopropanolamine is 42-48°C.

[0016] Furthermore, in step (2), the concentration of hydrogen peroxide is 10 to 35 wt %, and the feed molar ratio of diisopropanolamine to hydrogen peroxide is 1:1 to 1.2.

[0017] Furthermore, the feed molar ratio of diisopropanolamine to hydrogen peroxide is 1:1 to 1.05.

[0018] Furthermore, in step (2), the feed rate of diisopropanolamine is 0.98 to 1.18 times the feed rate of hydrogen peroxide.

[0019] Furthermore, in step (2), the feed rate of hydrogen peroxide is 1 g / min.

[0020] Furthermore, in step (2), the residence time of hydrogen peroxide and diisopropanolamine in the microchannel reactor is 5 to 30 seconds, the reaction temperature is 55 to 65° C., and the reaction pressure is 0.1 to 0.5 MPa.

[0021] Furthermore, in step (3), the diisopropylhydroxylamine aqueous solution flowing out of the microchannel reactor is cooled to room temperature, acetone is added and then cooled to 0-4° C., crystals are collected by suction filtration, and the crystals are washed with cold acetone to remove residual mother liquor, and then dried in air or in a vacuum drying oven to remove residual acetone, thereby obtaining pure diisopropylhydroxylamine crystals.

[0022] A device for the method of synthesizing diisopropylhydroxylamine in any one of the above-mentioned microchannel reactors, comprising a feed module, a reaction module, a product collection module and a temperature control module;

[0023] The feed module includes a diisopropanolamine raw material tank, a metering pump A, a diisopropanolamine heating tank, a metering pump B, a hydrogen peroxide raw material tank and a metering pump C;

[0024] The reaction module comprises a microchannel reactor; the inner diameter of the microchannel of the microchannel reactor is 0.10 to 2.0 mm, and the length of the microchannel is 5 to 50 m;

[0025] The collection module includes a product storage tank;

[0026] The diisopropanolamine raw material tank, metering pump A, and diisopropanolamine heating tank are connected in sequence through pipelines; the diisopropanolamine heating tank is connected to the feed port of the microchannel reactor through metering pump B and flow regulating valve A; the hydrogen peroxide raw material tank is connected to the feed port of the microchannel reactor through metering pump C and flow regulating valve B; the discharge port of the microchannel reactor is connected to the product storage tank through a pipeline;

[0027] The temperature control module includes a PLC controller and a temperature controller A, a temperature controller B and a temperature controller C connected to the controller, wherein the temperature controller A is used to control the temperature of the diisopropanolamine heating tank, the temperature controller B is used to control the temperature of the microchannel reactor, and the temperature controller C is used to control the temperature of the product storage tank.

[0028] Furthermore, a back pressure valve is provided on the discharge port of the microchannel reactor, and the back pressure valve is used to adjust the reaction pressure in the microchannel reactor.

[0029] Beneficial effects of the present invention:

[0030] Microchannel reactors have significant advantages in the reaction of hydrogen peroxide oxidation of diisopropanolamine to generate diisopropanol hydroxylamine. Since the reaction rate of hydrogen peroxide oxidation of diisopropanolamine is fast, and diisopropanol hydroxylamine and diisopropanolamine have similar physical properties, it is necessary to separate the product and reactant in time to avoid excessive oxidation to ammonium nitrate. The microreactor channel, due to its efficient mass transfer and heat transfer performance, can make the reaction conditions of hydrogen peroxide oxidation of diisopropanolamine easier to control, reduce the generation of by-products, and achieve high selectivity and high yield of diisopropanol hydroxylamine. Compared with the prior art, the present invention has the following effects:

[0031] 1) The reactants complete the mixed reaction in a very short time in the microchannel reactor, which can greatly increase the reaction speed and significantly reduce energy consumption.

[0032] 2) After the reaction is completed, the product and the reactant can be effectively separated, and the excessive oxidation of diisopropylhydroxylamine and hydrogen peroxide to generate by-products under long-term contact is effectively inhibited, and the yield, selectivity and purity of the product are greatly improved.

[0033] 3) Precise temperature control and pressure control are used to ensure the consistency of the reaction and product quality, and to achieve long-term safe and stable reactions and post-processing, thereby reducing production costs and ensuring production economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a process flow chart of a method for synthesizing diisopropylhydroxylamine using a microchannel reactor.

[0035] Figure 2 The present invention is a schematic structural diagram of a device for synthesizing diisopropylhydroxylamine using a microchannel reactor. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and a preferred implementation manner.

[0037] See also Figure 1 and Figure 2 , the present invention provides a device for synthesizing diisopropylhydroxylamine in a microchannel reactor, comprising a feeding module, a reaction module, a product collection module and a temperature control module;

[0038] The feeding module includes a diisopropanolamine raw material tank 1, a metering pump A3, a diisopropanolamine heating tank 6, a metering pump B5, a flow regulating valve A8, a hydrogen peroxide raw material tank 2, a metering pump C4 and a flow regulating valve B7;

[0039] The reaction module includes a microchannel reactor 9 and a back pressure valve 10; the microchannel inner diameter of the microchannel reactor 9 is 0.10-2.0 mm, and the microchannel length is 5-50 m; the microchannel reactor 9 is provided with a first feed inlet and a second feed inlet,

[0040] The collection module includes a product storage tank 11, in which a stirrer is provided;

[0041] The diisopropanolamine raw material tank 1, the metering pump A3, and the diisopropanolamine heating tank 6 are connected in sequence through pipelines, and the diisopropanolamine heating tank 6 is connected to the first feed port of the microchannel reactor 9 through the metering pump B5 and the flow regulating valve A8; the hydrogen peroxide raw material tank 2 is connected to the second feed port of the microchannel reactor 9 through the metering pump C4 and the flow regulating valve B7; the discharge port of the microchannel reactor 9 is connected to the product storage tank 11 through a pipeline and a back pressure valve 10;

[0042] The temperature control module includes a PLC controller and a temperature controller A12, a temperature controller B13 and a temperature controller C14 connected to the controller. The temperature controller A12 is used to control the temperature of the diisopropanolamine heating tank 6, the temperature controller B13 is used to control the temperature of the microchannel reactor 9, and the temperature controller C14 is used to control the temperature of the product storage tank 11.

[0043] Both the diisopropanolamine heating tank 6 and the product storage tank 11 are provided with a heating device, which may be an electric heating tube or a heating shell arranged outside the tank body, and a heating medium is introduced into the heating shell.

[0044] The method for synthesizing diisopropylhydroxylamine using the above device is:

[0045] 1) First, the raw material diisopropanolamine 1 stored in the diisopropanolamine raw material tank 1 is transported to the diisopropanolamine heating tank 6 by the metering pump A3 for heating and melting, and the heating temperature is controlled by the temperature controller A12;

[0046] 2) The heated and melted diisopropanolamine enters the microchannel reactor 9 through the metering pump B5 and the valve A8 to control the flow rate; the hydrogen peroxide stored in the hydrogen peroxide raw material tank 2 enters the microchannel reactor 9 after the flow rate is controlled by the metering pump C4 and the flow regulating valve B7; the diisopropanolamine and the hydrogen peroxide react at the set temperature and pressure, the reaction temperature is controlled by the temperature controller B13, and the reaction pressure is controlled by the back pressure valve 10;

[0047] 3) After the reaction is completed, the product flows into the product storage tank 11 for cooling, and the cooling temperature is controlled by the temperature controller C14;

[0048] 4) The cooled diisopropanolamine aqueous solution is discharged from the product storage tank 11 and recrystallized with acetone solvent to obtain high-purity diisopropanolamine.

[0049] The technical effects of the present invention are described in detail below through Examples 1 to 4. The raw materials and reagents used in the following examples are all commercially available.

[0050] Example 1

[0051] (1) Weigh 13.3 g of diisopropanolamine and transfer it to the diisopropanolamine heating tank 6 via metering pump A3 for heating and melting; the heating temperature is 45° C. and the heating time is 15 minutes;

[0052] (2) 13.3 g of melted diisopropanolamine liquid and 11.3 g of 30 wt% hydrogen peroxide were fed into the microchannel reactor 9 at feed rates of 1.18 g / min and 1 g / min, respectively, for reaction; the feed molar ratio of diisopropanolamine to hydrogen peroxide was 1:1; the reaction temperature was 60° C., the reaction pressure was 0.3 MPa, and the residence time of the reactants was 12 s;

[0053] (3) After the reaction is completed, the diisopropylhydroxylamine aqueous solution flows into the product storage tank 11 for cooling at a temperature of 30° C., with stirring while cooling;

[0054] (4) The cooled diisopropylhydroxylamine aqueous solution was discharged from the product storage tank 11, and recrystallized with acetone. After drying, 14.80 g of diisopropylhydroxylamine was obtained. The yield of Example 1 was calculated to be 99.6%, and the selectivity was 99.4%.

[0055] Example 2

[0056] (1) Weigh 13.3 g of diisopropanolamine and transfer it to the diisopropanolamine heating tank 6 via metering pump A3 for heating and melting; the heating temperature is 48° C. and the heating time is 13 minutes;

[0057] (2) 13.3 g of melted diisopropanolamine liquid and 9.7 g of 35 wt% hydrogen peroxide were fed into the microchannel reactor 9 at feed rates of 1.12 g / min and 1 g / min, respectively, for reaction; the feed molar ratio of diisopropanolamine to hydrogen peroxide was 1:1.05; the reaction temperature was 63° C., the reaction pressure was 0.2 MPa, and the residence time of the reactants was 8 s;

[0058] (3) After the reaction is completed, the diisopropylhydroxylamine aqueous solution flows into the product storage tank 11 for cooling at a temperature of 30° C., with stirring while cooling;

[0059] (4) The cooled diisopropylhydroxylamine aqueous solution was discharged from the product storage tank 11, and recrystallized with acetone. After drying, 14.43 g of diisopropylhydroxylamine was obtained. The yield of Example 2 was calculated to be 97.0%, and the selectivity was 96.9%.

[0060] Example 3

[0061] (1) Weigh 13.3 g of diisopropanolamine and transfer it to the diisopropanolamine heating tank 6 via metering pump A3 for heating and melting; the heating temperature is 42° C. and the heating time is 18 minutes;

[0062] (2) 13.3 g of melted diisopropanolamine liquid and 11.3 g of 30 wt% hydrogen peroxide were fed into a microchannel reactor 9 at feed rates of 0.98 g / min and 1 g / min, respectively, for reaction; the feed molar ratio of diisopropanolamine to hydrogen peroxide was 1:1.2; the reaction temperature was 58° C., the reaction pressure was 0.4 MPa, and the residence time of the reactants was 20 s;

[0063] (3) After the reaction is completed, the diisopropylhydroxylamine aqueous solution flows into the product storage tank 11 for cooling at a temperature of 30° C., with stirring while cooling;

[0064] (4) The cooled diisopropylhydroxylamine aqueous solution was discharged from the product storage tank 11, and recrystallized with acetone. After drying, 14.06 g of diisopropylhydroxylamine was obtained. The yield of Example 3 was calculated to be 94.6%, and the selectivity was 94.4%.

[0065] Example 4

[0066] (1) Weigh 13.3 g of diisopropanolamine and transfer it to the diisopropanolamine heating tank 6 via metering pump A3 for heating and melting; the heating temperature is 45° C. and the heating time is 15 minutes;

[0067] (2) 13.3 g of melted diisopropanolamine liquid and 33.9 g of 10 wt % hydrogen peroxide were fed into a microchannel reactor 9 at feed rates of 1.18 g / min and 1 g / min, respectively, for reaction; the feed molar ratio of diisopropanolamine to hydrogen peroxide was 1:1; the reaction temperature was 60° C., the reaction pressure was 0.3 MPa, and the residence time of the reactants was 30 s;

[0068] (3) After the reaction is completed, the diisopropylhydroxylamine aqueous solution flows into the product storage tank 11 for cooling at a temperature of 30° C., with stirring while cooling;

[0069] (4) The cooled diisopropylhydroxylamine aqueous solution was discharged from the product storage tank 11, and recrystallized with acetone. After drying, 13.84 g of diisopropylhydroxylamine was obtained. The yield of Example 4 was calculated to be 93.2%, and the selectivity was 92.9%.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the protection scope of the present invention.

Claims

1. A method for synthesizing diisopropylhydroxylamine using a microchannel reactor, characterized in that: The following steps are involved: (1) heating diisopropanolamine until it melts; (2) The melted liquid diisopropanolamine and hydrogen peroxide are respectively introduced into the microchannel reactor through metering pumps for reaction, and the reaction temperature and reaction pressure are controlled by an external controller. (3) After the reaction is completed, the diisopropylhydroxylamine aqueous solution flowing out of the microchannel reactor is collected, cooled and recrystallized to obtain the product diisopropylhydroxylamine.

2. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 1, characterized in that: In step (1), the heating temperature of diisopropanolamine is 42-48°C.

3. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 1, characterized in that: In step (2), the concentration of hydrogen peroxide is 10-35 wt %, and the feed molar ratio of diisopropanolamine to hydrogen peroxide is 1:1-1.

2.

4. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 3, characterized in that: The feed molar ratio of diisopropanolamine to hydrogen peroxide is 1:1-1.

05.

5. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 1, characterized in that: In step (2), the feed rate of diisopropanolamine is 0.98 to 1.18 times the feed rate of hydrogen peroxide.

6. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 5, characterized in that: In step (2), the feed rate of hydrogen peroxide is 1 g / min.

7. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 1, characterized in that: In step (2), the residence time of hydrogen peroxide and diisopropanolamine in the microchannel reactor is 5 to 30 seconds, the reaction temperature is 55 to 65° C., and the reaction pressure is 0.1 to 0.5 MPa.

8. The method for synthesizing diisopropylhydroxylamine by a microchannel reactor according to claim 1, characterized in that: In step (3), the diisopropylhydroxylamine aqueous solution flowing out of the microchannel reactor is cooled to room temperature, acetone is added and then cooled to 0-4° C., crystals are collected by suction filtration, and the crystals are washed with cold acetone to remove residual mother liquor, and then dried in air or in a vacuum drying oven to remove residual acetone, thereby obtaining pure diisopropylhydroxylamine crystals.

9. A device for the method for synthesizing diisopropylhydroxylamine in a microchannel reactor according to any one of claims 1 to 8, characterized in that: It includes a feeding module, a reaction module, a product collection module and a temperature control module; The feed module includes a diisopropanolamine raw material tank, a metering pump A, a diisopropanolamine heating tank, a metering pump B, a hydrogen peroxide raw material tank and a metering pump C; The reaction module comprises a microchannel reactor; the inner diameter of the microchannel of the microchannel reactor is 0.10 to 2.0 mm, and the length of the microchannel is 5 to 50 m; The collection module includes a product storage tank; The diisopropanolamine raw material tank, metering pump A, and diisopropanolamine heating tank are connected in sequence through pipelines; the diisopropanolamine heating tank is connected to the feed port of the microchannel reactor through metering pump B and flow regulating valve A; the hydrogen peroxide raw material tank is connected to the feed port of the microchannel reactor through metering pump C and flow regulating valve B; the discharge port of the microchannel reactor is connected to the product storage tank through a pipeline; The temperature control module includes a PLC controller and a temperature controller A, a temperature controller B and a temperature controller C connected to the controller, wherein the temperature controller A is used to control the temperature of the diisopropanolamine heating tank, the temperature controller B is used to control the temperature of the microchannel reactor, and the temperature controller C is used to control the temperature of the product storage tank.

10. The device according to claim 9, characterized in that A back pressure valve is provided on the discharge port of the microchannel reactor, and the back pressure valve is used to adjust the reaction pressure in the microchannel reactor.

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