Device and method for continuously synthesizing diethylhydroxylamine based on gradient filled titanium silicalite molecular sieve

Abstract

The invention relates to the technical field of chemical production, in particular to a device and a method for continuously synthesizing diethylhydroxylamine based on gradient filling of a titanium silicalite molecular sieve. The device comprises a horizontal tubular reactor which is filled with a titanium silicalite molecular sieve catalyst in an axial three-stage gradient filling manner along the material flowing direction, specifically, an inlet section is filled with a large-particle spherical catalyst; the particle size of the large-particle spherical catalyst is greater than 2mm and less than or equal to 3mm; the middle section is filled with a medium-particle catalyst; the particle size of the medium particle catalyst is greater than 1mm and less than or equal to 2mm; an outlet section small particle catalyst; and the particle size of the small-particle catalyst is greater than 0.5 mm and less than or equal to The method specifically comprises the following steps: mixing diethylamine and a solvent to prepare a primarily prepared solution; respectively pumping the primarily prepared solution and hydrogen peroxide into a horizontal tubular reactor for reaction; and collecting the reaction liquid at the outlet end of the horizontal tubular reactor. Efficient and stable operation of the reaction process is realized by adopting a continuous production process, and the method is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of chemical production, and particularly relates to a device and method for synthesizing diethylhydroxylamine in a continuous mode based on gradient filling of titanium silicalite. BACKGROUND

[0002] Diethylhydroxylamine (DEHA) is an important chemical intermediate. At room temperature, the pure product is a colorless transparent liquid, and the industrial product is a light yellow transparent liquid with an amine odor, easily soluble in water, ethanol, diethyl ether, chloroform, tetrahydrofuran and benzene, etc. Diethylhydroxylamine is widely used as a polymerization inhibitor and end group terminator for olefin monomers and conjugated olefins due to its high polymerization inhibition efficiency, non-toxicity and easy separation. In addition, it is often used as a good stabilizer for photosensitive resin, photosensitive adhesive and synthetic resin, and is often used as a photochemical smog inhibitor in environmental protection.

[0003] With the rapid development of the fields of chemical industry, materials and environmental protection in recent years and the wide application of diethylhydroxylamine in these fields, the demand for diethylhydroxylamine is increasing. At present, the main method for synthesizing diethylhydroxylamine in industry is the oxidation of triethylamine. This method uses triethylamine as raw material to prepare diethylhydroxylamine through two processes of oxidation and cracking. However, this process has the disadvantages of multiple reaction steps, many by-products and long production cycle. In addition, cracking process not only produces tar but also generates ethylene gas, which has the risk of being flammable and explosive.

[0004] In recent years, a route for directly oxidizing diethylamine and hydrogen peroxide to obtain diethylhydroxylamine under the catalysis of titanium silicalite has been developed. This method has the advantages of short reaction steps, less equipment investment and fewer by-products, and conforms to the development trend of green chemistry. However, this process still has some technical barriers, such as low utilization rate of hydrogen peroxide due to its easy decomposition and further oxidation of diethylhydroxylamine to by-products such as nitrones, which causes low selectivity of diethylhydroxylamine and great difficulty in separation and purification.

[0005] The patent application with the publication number CN113797966A discloses a preparation method of diethylhydroxylamine. Zinc-cadmium alloy nanoparticles (ZnCd) are used as the core and titanium silicalite (TS-1, MFI structure) is used as the shell to form a "core-shell" catalyst structure by wrapping the alloy particles outside. Diethylhydroxylamine is synthesized by catalytic oxidation of diethylamine with methanol as the solvent. The conversion rate of diethylamine is between 51-55%, and the selectivity of diethylhydroxylamine is between 89-93%. Although this method improves the selectivity of diethylhydroxylamine through synergistic catalysis, the raw materials of the catalyst used have great toxicity, the preparation process is harsh, the mechanical strength is low, and the cost is high, which makes it difficult to realize large-scale production.

[0006] In summary, the existing preparation of diethyl hydroxylamine technology has the problems of complicated process route, high catalyst cost and low selectivity caused by excessive oxidation to generate byproducts. SUMMARY

[0007] In view of the problems of complicated process route, high catalyst cost and poor controllability caused by insufficient activity in the early stage and excessive oxidation in the later stage of the reaction of the conventional synthesis of diethyl hydroxylamine technology, the present application provides a device and method for continuous synthesis of diethyl hydroxylamine based on gradient filling of titanium silicalite.

[0008] The technical scheme provided by the present application optimizes the catalyst loading mode, solves the problems of insufficient reaction in the early stage and excessive oxidation in the later stage to generate byproduct nitroketone caused by uniform catalyst loading, realizes efficient preparation of diethyl hydroxylamine, improves the selectivity of diethyl hydroxylamine, shortens the reaction time, and is suitable for industrial production.

[0009] In the first aspect, the present application provides a device for continuous synthesis of diethyl hydroxylamine based on gradient filling of titanium silicalite, which adopts the following technical scheme: A device for continuous synthesis of diethyl hydroxylamine based on gradient filling of titanium silicalite, the device comprises a horizontal tubular reactor, the horizontal tubular reactor is filled with titanium silicalite catalyst in an axial three-stage gradient filling mode along the material flow direction, specifically: The inlet section is filled with large-particle spherical catalyst; the inlet section is a position 30% of the length of the horizontal tubular reactor from the material inlet; 2mm < the particle size of the large-particle spherical catalyst ≤ 3mm; The middle section is filled with medium-particle catalyst; the middle section is a position 30% of the length of the horizontal tubular reactor from the inlet section to the material outlet direction; 1mm < the particle size of the medium-particle catalyst ≤ 2mm; The outlet section is filled with small-particle catalyst; the outlet section is a position 40% of the length of the horizontal tubular reactor from the middle section to the material outlet direction; 0.5mm < the particle size of the small-particle catalyst ≤ 1mm.

[0010] The technical scheme provided by the present application optimizes the catalyst loading mode, solves the problems of insufficient reaction in the early stage and excessive oxidation in the later stage to generate byproduct nitroketone caused by uniform catalyst loading, realizes efficient preparation of diethyl hydroxylamine, improves the selectivity of diethyl hydroxylamine, shortens the reaction time, and is suitable for industrial production.

[0011] Optionally, the horizontal tubular reactor is provided with two hydrogen peroxide supplement injection interfaces on the pipe wall, respectively located at the starting position of the middle section and the starting position of the outlet section.

[0012] In the technical scheme of the present application, two hydrogen peroxide supplementary injection interfaces are arranged on the wall of the horizontal tubular reactor respectively, so that the hydrogen peroxide is supplemented in stages.

[0013] Optionally, the horizontal tubular reactor is provided with a jacket type constant temperature system, and the constant temperature cavity is formed by the jacket and the outer wall of the horizontal tubular reactor.

[0014] In the technical scheme of the present application, the circulating medium is contained in the constant temperature cavity formed by the jacket and the outer wall of the horizontal tubular reactor, so that the temperature is controlled.

[0015] Optionally, the titanium-silicon molecular sieve is TS-1 type, and the molar ratio of silicon to titanium is 50-80.

[0016] In a second aspect, the present application provides a method for continuously preparing diethyl hydroxylamine by using the above device, which adopts the following technical scheme: A method for continuously preparing diethyl hydroxylamine by using the above device, the method specifically comprises the following steps: mixing and preparing diethylamine and a solvent in proportion to obtain a primary solution; pumping the primary solution and hydrogen peroxide into the horizontal tubular reactor respectively for reaction; collecting the reaction liquid at the outlet end of the horizontal tubular reactor, and obtaining the diethyl hydroxylamine.

[0017] Optionally, the hydrogen peroxide is fed in stages, and the feeding modes are as follows: pumping into the inlet end of the horizontal tubular reactor and secondary supplementary injection at the two hydrogen peroxide supplementary injection interfaces of the horizontal tubular reactor.

[0018] Optionally, the solvent is any one of tetrahydrofuran, 1,4-dioxane and acetone.

[0019] Optionally, the molar ratio of the diethylamine to the solvent is (1-2):(1-2).

[0020] In a specific embodiment, the molar ratio of the diethylamine to the solvent is 1:1.5, 1:2 or 2:1.

[0021] In the present application, the solvent functions to dilute the diethylamine, so as to avoid excessive oxidation due to too fast oxidation.

[0022] Optionally, the volume ratio of the primary solution to the hydrogen peroxide is (1-7):1.

[0023] Optionally, the volume ratio of the primary solution to the hydrogen peroxide is (2-6):1.

[0024] Optionally, the volume ratio of the primary solution to the hydrogen peroxide is (2.8-5.1):1.

[0025] In one specific embodiment, the volume ratio of the primary solution and the hydrogen peroxide is 2.8:1, 4.4:1, 4.5:1, 5.1:1.

[0026] In some specific embodiments, the volume ratio of the primary solution and the hydrogen peroxide is (2.8-4.4):1, (2.8-4.5):1, (4.4-4.5):1, (4.4-5.1):1, (4.5-5.1):1.

[0027] In the prior art, the reaction of diethylamine and hydrogen peroxide to prepare diethylhydroxylamine is mostly carried out with excess (or equal amount) of hydrogen peroxide over diethylamine. However, the present application tends to use excess diethylamine to avoid excessive oxidation of diethylhydroxylamine caused by excessive hydrogen peroxide. For example, the actual ratio of diethylamine, hydrogen peroxide and tetrahydrofuran in Example 1 is 2:1:3.

[0028] Optionally, the temperature for the continuous preparation of diethylhydroxylamine is 40-60℃.

[0029] Optionally, the temperature for the continuous preparation of diethylhydroxylamine is 50-60℃.

[0030] Optionally, the temperature for the continuous preparation of diethylhydroxylamine is 40-50℃.

[0031] In one specific embodiment, the temperature for the continuous preparation of diethylhydroxylamine is 40℃, 50℃ or 60℃.

[0032] Optionally, the method further comprises a post-treatment step, specifically: the reaction solution is subjected to rectification to recover unreacted raw materials and solvents, and after extraction separation of the aqueous phase, the organic phase is subjected to rectification purification to obtain diethylhydroxylamine product.

[0033] In summary, the present application has at least one of the following beneficial technical effects: The present application fills the titanium silicalite molecular sieve in an axial gradient manner: the inlet section is filled with 2-3mm large-particle-size titanium silicalite molecular sieve to effectively slow down the intense heat release caused by high concentration of reactants at the beginning of the reaction, and the outlet section is filled with 0.5-1mm small-particle-size titanium silicalite molecular sieve to increase the active site density and strengthen the mass transfer of low concentration of reactants in the later stage of the reaction. By optimizing the particle size distribution of the catalyst, the flow dynamics of the reactants is improved, which balances the system pressure and increases the effective wetting area of the catalyst.

[0034] Compared with the related art, the catalyst used in the technical scheme of the present application has no obvious toxicity, and can effectively improve the service life of the catalyst. The segmented feeding mode of hydrogen peroxide in the present application solves the problem of catalyst sintering caused by local over-temperature of the reaction system, optimizes the distribution of the oxidizing agent, and improves the selectivity of diethyl hydroxylamine to more than 93%, effectively inhibiting the generation of nitroketone as an oxidation by-product.

[0035] The gradient filling structure of the present application effectively inhibits the enrichment of reaction intermediates on the surface of the catalyst, prolongs the service life of the catalyst, and after continuous operation for 500 hours, the selectivity of the catalyst to the target product remains more than 97% of the initial selectivity (measured after 3 hours of reaction).

[0036] The present application adopts a continuous production process to realize efficient and stable operation of the reaction process, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A schematic diagram of the device for continuous synthesis of diethyl hydroxylamine based on gradient filling of titanium silicalite molecular sieve according to the present application. DETAILED DESCRIPTION

[0038] Before describing the embodiments of the present application in detail, it should be understood that the terms used herein are for the purpose of describing specific embodiments only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term belongs.

[0039] It should be noted that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, unless otherwise stated, the meaning of "multiple" is two or more.

[0040] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values stated. The ranges or values should be construed to include values approximately around the ranges or values. For numerical ranges, the endpoints of the various ranges, the endpoints of the various ranges and individual point values between the endpoints of the various ranges, and the individual point values can be combined to form one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0041] In the present application, the term "comprising" or "including" is an open-ended expression, i.e. including the contents indicated in the present application, but not excluding other aspects.

[0042] The present application provides a device for continuous synthesis of diethyl hydroxylamine based on gradient filling of titanium silicalite molecular sieve.

[0043] The device comprises a horizontal tubular reactor, which is filled with titanium silicalite catalyst in an axial three-stage gradient filling mode along the material flow direction, specifically: the inlet section is filled with large-particle spherical catalyst; the inlet section is a position 30% of the length of the horizontal tubular reactor from the material inlet; 2mm < the particle size of the large-particle spherical catalyst ≤ 3mm; the middle section is filled with medium-particle catalyst; the middle section is a position 30% of the length of the horizontal tubular reactor from the inlet section to the material outlet direction; 1mm < the particle size of the medium-particle catalyst ≤ 2mm; the outlet section is small-particle catalyst; the outlet section is a position 40% of the length of the horizontal tubular reactor from the middle section to the material outlet direction; 0.5mm < the particle size of the small-particle catalyst ≤ 1mm.

[0044] Among them, the pipe wall of the horizontal tubular reactor is provided with two hydrogen peroxide supplementary injection interfaces, respectively located at the starting position of the middle section and the starting position of the outlet section, to realize the staged supplement of the oxidant.

[0045] Among them, the horizontal tubular reactor is provided with a jacket type constant temperature system, which forms a constant temperature cavity with the jacket and the outer wall of the horizontal tubular reactor, for containing circulating medium for temperature control.

[0046] The application also provides a method for preparing diethyl hydroxylamine by using the above device.

[0047] The method specifically comprises the following steps: mixing and preparing diethylamine and solvent in proportion to obtain a primary preparation solution; pumping the primary preparation solution and hydrogen peroxide into the horizontal tubular reactor for reaction; collecting the reaction liquid at the outlet end of the horizontal tubular reactor to obtain the diethyl hydroxylamine.

[0048] Among them, the feeding mode of the hydrogen peroxide is segmented feeding, which is: pumped into the inlet end of the horizontal tubular reactor and secondarily supplemented and injected at the two hydrogen peroxide supplementary injection interfaces of the horizontal tubular reactor.

[0049] In addition, the method further comprises a post-treatment step, specifically: the reaction liquid is subjected to rectification to recover unreacted raw materials and solvent, and after extraction separation of the aqueous phase, the organic phase is subjected to rectification purification to obtain the diethyl hydroxylamine product.

[0050] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application.

[0051] Unless otherwise specified, the techniques or conditions in the examples were carried out according to the techniques or conditions described in the literature or according to the product instructions. Unless otherwise specified, the reagents or instruments used were conventional products that can be obtained commercially.

[0052] The horizontal tubular reactor used in the following examples was made of 316L stainless steel, with a length of 1.5 m and an inner diameter of 50 mm. The inside of the reactor was filled with titanium silicalite molecular sieve catalyst in an axial three-stage gradient filling manner along the material flow direction: 2-3 mm large particle spherical catalyst was filled in the inlet section (0-30% length), 1-2 mm medium particle catalyst was filled in the middle section (30-60% length), and 0.5-1 mm small particle catalyst was filled in the outlet section (60-100% length).

[0053] The application will be further described in detail below in combination with examples, comparative examples, and test results.

[0054] Example 1

[0055] The present example provides a horizontal tubular continuous reaction system based on gradient filling of titanium silicalite molecular sieve for synthesizing diethylhydroxylamine. The system includes a raw material feeding unit, a gradient filling tubular reactor, and a product processing unit. The gradient filling tubular reactor is the device for continuous synthesis of diethylhydroxylamine based on gradient filling of titanium silicalite molecular sieve according to the present application.

[0056] The raw material feeding unit includes a diethylamine and tetrahydrofuran mixed liquid storage tank and a metering pump, and a hydrogen peroxide storage tank and a metering pump. The diethylamine and tetrahydrofuran mixed liquid storage tank is made of 316L stainless steel. The product collection unit includes a raw material and solvent recovery system, an extraction separation system, and a product refining system.

[0057] Reference Figure 1 The gradient filling tubular reactor is made of 316L stainless steel, with a design size of 1.5 m in length and 50 mm in inner diameter, and the inside is filled with titanium silicalite molecular sieve (TS-1). The inlet section (0-0.45 m) is filled with large particle spherical titanium silicalite molecular sieve (2 mm < particle size of large particle spherical titanium silicalite molecular sieve ≤ 3 mm), the middle section (0.45-0.9 m) is filled with medium particle spherical titanium silicalite molecular sieve (1 mm < particle size of medium particle spherical titanium silicalite molecular sieve ≤ 2 mm), and the outlet section (0.9-1.5 m) is filled with small particle spherical titanium silicalite molecular sieve (0.5 mm < small particle spherical titanium silicalite molecular sieve ≤ 1 mm). At the same time, a precision filter (0.5 μm sintered metal) is also installed at the outlet end to intercept titanium silicalite molecular sieve powder.

[0058] Two hydrogen peroxide supplement injection interfaces are arranged on the wall of the gradient filling tubular reactor, which are respectively located at the positions of 0.45 m and 0.9 m from the inlet end of the reactor, and the injection amounts are 25% and 50% of the total injection amount of hydrogen peroxide respectively. The first injection point of hydrogen peroxide is the inlet end of the reactor, and the injection amount is 50% of the total injection amount of hydrogen peroxide, which is injected simultaneously with the initial solution. In addition, a jacket is arranged outside the gradient filling tubular reactor, and the jacket and the outer wall of the reaction tube form a constant temperature cavity for containing circulating medium.

[0059] The method for preparing diethyl hydroxylamine by using the above-mentioned gradient filling tubular reactor (device for continuously synthesizing diethyl hydroxylamine based on gradient filling of titanium-silicon molecular sieve) comprises the following steps: (1) mixing diethylamine (2 mol) and tetrahydrofuran (3 mol) uniformly according to a molar ratio of 1:1.5 to obtain an initial solution; (2) pumping the initial solution and hydrogen peroxide (concentration of 30%, 1 mol) into the gradient filling tubular reactor according to a volume ratio of 4.4:1 for oxidation reaction. The feeding mode of hydrogen peroxide is stepwise feeding, which is injected at 0%, 30% and 60% of the length of the reactor, and the injection amounts are 50%, 25% and 25% of the total injection amount of hydrogen peroxide respectively, and the reaction temperature is 50°C.

[0060] (3) collecting the material at the outlet of the reactor.

[0061] It is known through gas chromatographic analysis that the selectivity of diethyl hydroxylamine is 96%. It is calculated that the utilization rate of hydrogen peroxide is 94.6%. After the reaction solution is subjected to rectification to recover unreacted raw materials and solvents, and the aqueous phase is separated by extraction, the organic phase is purified by rectification to obtain diethyl hydroxylamine product. It is known through gas chromatographic analysis that the purity of diethyl hydroxylamine is greater than 96%, and the water content is less than 2%. After continuous operation for 500 hours, the selectivity of the catalyst to the target product still remains more than 99% of the initial selectivity (measured at 3 hours of reaction).

[0062] Example 2

[0063] The embodiment provides a method for preparing diethyl hydroxylamine by using a device for continuously synthesizing diethyl hydroxylamine based on gradient filling of titanium-silicon molecular sieve. The difference between the embodiment and example 1 is that the solvent is acetone instead of tetrahydrofuran, and the rest of the operations remain the same as those in example 1.

[0064] The selectivity of diethylhydroxylamine was 93.2% by gas chromatography analysis. The utilization rate of hydrogen peroxide was 92.4% by calculation. The reaction liquid was subjected to rectification to recover unreacted raw materials and solvents, and the water phase was separated by extraction, and then the organic phase was purified by rectification to obtain diethylhydroxylamine product. The purity of diethylhydroxylamine was greater than 95% and the water content was less than 3% by gas chromatography analysis. After continuous operation for 500 hours, the selectivity of the catalyst to the target product remained more than 97% of the initial selectivity (measured at 3 hours of reaction).

[0065] Example 3

[0066] This example provides a method for preparing diethylhydroxylamine by using a device for continuous synthesis of diethylhydroxylamine based on gradient-filled titanium-silicon molecular sieve. The difference between this example and Example 1 is that the volume ratio of the initial solution to hydrogen peroxide is 4.5:1, and the rest of the operations remain the same as in Example 1.

[0067] The selectivity of diethylhydroxylamine was 93.7% by gas chromatography analysis. The utilization rate of hydrogen peroxide was 92.7% by calculation. The reaction liquid was subjected to rectification to recover unreacted raw materials and solvents, and the water phase was separated by extraction, and then the organic phase was purified by rectification to obtain diethylhydroxylamine product. The purity of diethylhydroxylamine was greater than 95% and the water content was less than 3% by gas chromatography analysis. After continuous operation for 500 hours, the selectivity of the catalyst to the target product remained more than 98% of the initial selectivity (measured at 3 hours of reaction).

[0068] Example 4

[0069] This example provides a method for preparing diethylhydroxylamine by using a device for continuous synthesis of diethylhydroxylamine based on gradient-filled titanium-silicon molecular sieve. The difference between this example and Example 1 is that the molar ratio of diethylamine (2 mol) to tetrahydrofuran (4 mol) is 1:2; the volume ratio of the initial solution to hydrogen peroxide (1 mol) is 5.1:1, and the rest of the operations remain the same as in Example 1.

[0070] The selectivity of diethylhydroxylamine was 94.1% by gas chromatography analysis. The utilization rate of hydrogen peroxide was 92.7% by calculation. The reaction liquid was subjected to rectification to recover unreacted raw materials and solvents, and the water phase was separated by extraction, and then the organic phase was purified by rectification to obtain diethylhydroxylamine product. The purity of diethylhydroxylamine was greater than 96% and the water content was less than 3% by gas chromatography analysis. After continuous operation for 500 hours, the selectivity of the catalyst to the target product remained more than 99% of the initial selectivity (measured at 3 hours of reaction).

[0071] Example 5

[0072] The embodiment provides a method for preparing diethylhydroxylamine by using a device for continuously synthesizing diethylhydroxylamine based on gradient-filled titanium silicalite molecular sieves. The difference between the embodiment and example 1 is that the reaction temperature is 60 DEG C, and the rest of the operations are the same as those in example 1.

[0073] Gas chromatographic analysis shows that the selectivity of diethylhydroxylamine is 94.4%. It is calculated that the utilization rate of hydrogen peroxide is 93.8%. The reaction liquid is subjected to rectification to recover unreacted raw materials and solvents, and after the water phase is separated by extraction, the organic phase is subjected to rectification to obtain diethylhydroxylamine products. Gas chromatographic analysis shows that the purity of diethylhydroxylamine is greater than 95% and the water content is less than 3%. After continuous operation for 500 hours, the selectivity of the catalyst to the target product still remains more than 97% of the initial selectivity (measured after 3 hours of reaction).

[0074] Example 6

[0075] The embodiment provides a method for preparing diethylhydroxylamine by using a device for continuously synthesizing diethylhydroxylamine based on gradient-filled titanium silicalite molecular sieves. The difference between the embodiment and example 1 is that the reaction temperature is 60 DEG C, and the rest of the operations are the same as those in example 1.

[0076] Gas chromatographic analysis shows that the selectivity of diethylhydroxylamine is 94.4%. It is calculated that the utilization rate of hydrogen peroxide is 93.8%. The reaction liquid is subjected to rectification to recover unreacted raw materials and solvents, and after the water phase is separated by extraction, the organic phase is subjected to rectification to obtain diethylhydroxylamine products. Gas chromatographic analysis shows that the purity of diethylhydroxylamine is greater than 95% and the water content is less than 3%. After continuous operation for 500 hours, the selectivity of the catalyst to the target product still remains more than 97% of the initial selectivity (measured after 3 hours of reaction).

[0077] Example 7

[0078] The embodiment provides a method for preparing diethylhydroxylamine by using a device for continuously synthesizing diethylhydroxylamine based on gradient-filled titanium silicalite molecular sieves. The difference between the embodiment and example 1 is that the reaction temperature is 60 DEG C, and the rest of the operations are the same as those in example 1.

[0079] Gas chromatographic analysis shows that the selectivity of diethylhydroxylamine is 94.4%. It is calculated that the utilization rate of hydrogen peroxide is 93.8%. The reaction liquid is subjected to rectification to recover unreacted raw materials and solvents, and after the water phase is separated by extraction, the organic phase is subjected to rectification to obtain diethylhydroxylamine products. Gas chromatographic analysis shows that the purity of diethylhydroxylamine is greater than 95% and the water content is less than 3%. After continuous operation for 500 hours, the selectivity of the catalyst to the target product still remains more than 97% of the initial selectivity (measured after 3 hours of reaction).

[0080] Comparative Example 1 The present comparative example provides a method for preparing diethylhydroxylamine by using a continuous synthesis device of diethylhydroxylamine with titanium silicalite molecular sieve. The difference between the present comparative example and Example 1 is that the catalyst is filled in a single particle size (1-2 mm) and the filling length accounts for 100% of the reactor; the hydrogen peroxide is added in the reactor inlet in one-time drop, and the other operations are consistent with Example 1.

[0081] Gas chromatographic analysis shows that the selectivity of diethylhydroxylamine is 79.8%. It is calculated that the utilization rate of hydrogen peroxide is only 78.6%, which is much lower than that of Example 1. The reaction solution is subjected to rectification to recover unreacted raw materials and solvents, and the water phase is extracted and separated, and then the organic phase is subjected to rectification and purification to obtain diethylhydroxylamine product. Gas chromatographic analysis shows that the purity of diethylhydroxylamine is greater than 95% and the water content is less than 2%. After continuous operation for 500 hours, the selectivity of the catalyst to the target product decreases to 91% of the initial selectivity (measured at 3 hours of reaction).

[0082] Comparative Example 2 The present comparative example provides a method for preparing diethylhydroxylamine by using a continuous synthesis device of diethylhydroxylamine with titanium silicalite molecular sieve. The difference between the present comparative example and Example 1 is that the catalyst is filled in a single particle size (1-2 mm) and the filling length accounts for 100% of the reactor; the hydrogen peroxide is added in the reactor inlet in one-time drop, and the other operations are consistent with Example 1.

[0083] Gas chromatographic analysis shows that the selectivity of diethylhydroxylamine is 79.8%. It is calculated that the utilization rate of hydrogen peroxide is only 78.6%, which is much lower than that of Example 1. The reaction solution is subjected to rectification to recover unreacted raw materials and solvents, and the water phase is extracted and separated, and then the organic phase is subjected to rectification and purification to obtain diethylhydroxylamine product. Gas chromatographic analysis shows that the purity of diethylhydroxylamine is greater than 95% and the water content is less than 2%. After continuous operation for 500 hours, the selectivity of the catalyst to the target product decreases to 91% of the initial selectivity (measured at 3 hours of reaction).

[0084] Comparative Example 3 The present comparative example provides a method for preparing diethylhydroxylamine by using a continuous synthesis device of diethylhydroxylamine with titanium silicalite molecular sieve. The difference between the present comparative example and Example 1 is that the catalyst is filled in a single particle size (1-2 mm) and the filling length accounts for 100% of the reactor; the hydrogen peroxide is added in the reactor inlet in one-time drop, and the other operations are consistent with Example 1.

[0085] The selectivity of diethylhydroxylamine is 85.7% by gas chromatography analysis. The utilization rate of hydrogen peroxide is only 82.1% by calculation, which is much lower than that of Example 1. The reaction solution is subjected to rectification to recover unreacted raw materials and solvents, and the water phase is separated by extraction. The organic phase is purified by rectification to obtain diethylhydroxylamine product. The purity of diethylhydroxylamine is greater than 95% and the water content is less than 3% by gas chromatography analysis. After 500 hours of continuous operation, the selectivity of the catalyst to the target product is decreased to 89% of the initial selectivity (measured at 3 hours of reaction).

[0086] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0087] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves, characterized in that, The device includes a horizontal tubular reactor, wherein the horizontal tubular reactor is filled with a titanium-silicon molecular sieve catalyst in an axial three-stage gradient filling method along the material flow direction, specifically: The inlet section is filled with large spherical catalyst particles; the inlet section is located at a position that occupies 30% of the length of the horizontal tubular reactor from the material inlet; the particle size of the large spherical catalyst particles is 2mm < 3mm; The middle section is filled with medium-sized particulate catalyst; the middle section is located at a position that occupies 30% of the length of the horizontal tubular reactor from the inlet section to the material outlet; 1 mm < the particle size of the medium-sized particulate catalyst ≤ 2 mm; Small particle catalyst at the outlet section; the outlet section is the position from the middle section to the material outlet direction, occupying 40% of the length of the horizontal tubular reactor; 0.5mm < particle size of the small particle catalyst ≤ 1mm.

2. The apparatus according to claim 1, characterized in that, The horizontal tubular reactor has two hydrogen peroxide injection ports on its tube wall, located at the beginning of the middle section and the beginning of the outlet section, respectively.

3. The apparatus according to claim 1, characterized in that, The horizontal tubular reactor is equipped with a jacketed constant temperature system, which consists of a jacket and the outer wall of the horizontal tubular reactor forming a constant temperature cavity.

4. The apparatus according to claim 1, characterized in that, The titanium-silicon molecular sieve is of type TS-1, with a silicon-to-titanium molar ratio of 50-80.

5. A method for the continuous preparation of diethylhydroxylamine using the apparatus according to any one of claims 1-4, characterized in that, The method specifically includes the following steps: mixing diethylamine and solvent in a certain proportion to prepare a preliminary solution; pumping the preliminary solution and hydrogen peroxide into the horizontal tubular reactor for reaction; collecting the reaction solution at the outlet end of the horizontal tubular reactor to obtain the diethylhydroxylamine.

6. The method according to claim 5, characterized in that, The hydrogen peroxide is fed in stages, namely: pumped into the inlet of the horizontal tubular reactor and then supplemented by injection at the two hydrogen peroxide replenishment ports of the horizontal tubular reactor.

7. The method according to claim 5, characterized in that, The solvent is any one of tetrahydrofuran, 1,4-dioxane, and acetone.

8. The method according to claim 5, characterized in that, The molar ratio of the diethylamine to the solvent is (1~2):(1~2). Optionally, the volume ratio of the initial solution to the hydrogen peroxide is (1~7):1; Optionally, the volume ratio of the initial solution to the hydrogen peroxide is (2.8~5.1):

1.

9. The method according to claim 5, characterized in that, The continuous preparation temperature of diethylhydroxylamine is 40-60℃; Optionally, the continuous preparation temperature of diethylhydroxylamine is 50-60°C.

10. The method according to claim 5, characterized in that, The method also includes a post-processing step, specifically: the reaction solution is distilled to recover unreacted raw materials and solvents, the aqueous phase is extracted and separated, and the organic phase is purified by distillation to obtain diethylhydroxylamine product.

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