A device and method for continuous synthesis of diethylhydroxylamine based on gradient filling of titanium-silicon molecular sieve

Abstract

This application relates to the technical field of chemical production, specifically to an apparatus and method for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium-silicon molecular sieves. The apparatus includes a horizontal tubular reactor, which is filled with titanium-silicon molecular sieve catalyst in a three-stage axial gradient along the material flow direction. Specifically: the inlet section is filled with large spherical catalyst particles (2mm < particle size ≤ 3mm); the middle section is filled with medium-sized catalyst particles (1mm < particle size ≤ 2mm); and the outlet section is filled with small-sized catalyst particles (0.5mm < particle size ≤ 1mm). The method specifically involves: mixing diethylamine and a solvent to prepare a preliminary solution; pumping the preliminary solution and hydrogen peroxide separately into the horizontal tubular reactor for reaction; and collecting the reaction liquid at the outlet of the horizontal tubular reactor. This application utilizes a continuous production process to achieve efficient and stable operation of the reaction process, making it suitable for industrial production.

Description

Technical Field

[0001] This application relates to the technical field of chemical production, and in particular to an apparatus and method for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves. Background Technology

[0002] Diethylhydroxylamine (DEHA) is an important chemical intermediate. At room temperature, its pure form is a colorless, transparent liquid, while the industrial grade is a pale yellow, transparent liquid with an amine odor. It is readily soluble in water and also in ethanol, ether, chloroform, tetrahydrofuran, and benzene. Due to its high polymerization inhibition efficiency, non-toxicity, and ease of separation, DEHA is widely used as a polymerization inhibitor and end-group terminator for olefin monomers and conjugated olefins, as well as a slow-release agent in boiler feedwater and steam equipment. Furthermore, it is commonly used as a good stabilizer for photosensitive resins, photosensitive adhesives, and synthetic resins, and is frequently used as a photochemical smog suppressant in environmental protection.

[0003] With the rapid development of chemical, materials, and environmental protection fields in recent years, and given the wide range of applications of diethylhydroxylamine in these areas, the demand for diethylhydroxylamine is increasing daily. Currently, the main industrial method for synthesizing diethylhydroxylamine is the triethylamine oxidation process. This method uses triethylamine as a raw material and prepares diethylhydroxylamine through a two-step process of oxidation and cracking. However, this process has drawbacks such as multiple reaction steps, numerous byproducts, and a long production cycle. Furthermore, the cracking process not only produces tar but also generates ethylene gas, posing a flammable and explosive risk.

[0004] In recent years, a route has been developed to directly oxidize diethylamine and hydrogen peroxide to diethylhydroxylamine using titanium-silicon molecular sieves as raw materials. This method has advantages such as short reaction steps, low equipment investment, and few byproducts, which aligns with the trend of green chemistry. However, this process still faces some technical barriers, such as the easy decomposition of hydrogen peroxide leading to low utilization, and the easy further oxidation of diethylhydroxylamine by hydrogen peroxide to byproducts such as nitrones, resulting in low selectivity and difficulty in separation and purification.

[0005] Chinese patent CN113797966A discloses a method for preparing diethylhydroxylamine. This method uses zinc-cadmium alloy nanoparticles (ZnCd) as the core and a titanium-silicon molecular sieve (TS-1, MFI structure) as the shell, forming a core-shell catalyst structure. Methanol is used as the solvent to catalyze the oxidation of diethylamine to synthesize diethylhydroxylamine. 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 catalyst used has high toxicity of the raw materials, a demanding preparation process, low mechanical strength, and high cost, making large-scale production difficult.

[0006] In summary, existing technologies for preparing diethylhydroxylamine suffer from problems such as cumbersome process routes, high catalyst costs, and low selectivity due to easy over-oxidation and the generation of byproducts. Summary of the Invention

[0007] Given that traditional technologies for synthesizing diethylhydroxylamine have problems such as complicated process routes, high catalyst costs, and the uniform packing method of conventional tubular reactor catalysts, which can easily lead to insufficient activity in the early stage of the reaction and excessive oxidation in the later stage, resulting in poor reaction controllability, this application provides an apparatus and method for continuous synthesis of diethylhydroxylamine based on gradient-packed titanium silicate molecular sieves.

[0008] In a first aspect, this application provides an apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves, employing the following technical solution:

[0009] An apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium-silicon molecular sieves, the apparatus comprising a horizontal tubular reactor, wherein the titanium-silicon molecular sieve catalyst is packed in an axial three-stage gradient filling manner along the material flow direction, specifically:

[0010] 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;

[0011] 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;

[0012] 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.

[0013] The technical solution provided in this application solves the problems of insufficient front-end reaction and easy over-oxidation in the rear-end to generate byproduct nitrone by optimizing the catalyst loading method. It achieves efficient preparation of diethylhydroxylamine, improves the selectivity of diethylhydroxylamine, shortens the reaction time, and is suitable for industrial production.

[0014] Optionally, 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.

[0015] In the technical solution of this application, hydrogen peroxide is replenished in stages by setting two hydrogen peroxide replenishment ports on the tube wall of the horizontal tubular reactor.

[0016] Optionally, the horizontal tubular reactor is equipped with a jacketed constant temperature system, which forms a constant temperature cavity with the jacket and the outer wall of the horizontal tubular reactor.

[0017] In the technical solution of this application, temperature control is achieved by filling a constant temperature cavity formed by the jacket and the outer wall of the horizontal tubular reactor with circulating medium.

[0018] Optionally, the titanium-silicon molecular sieve is of type TS-1, and the silicon-to-titanium molar ratio is 50-80.

[0019] Secondly, this application provides a method for the continuous preparation of diethylhydroxylamine using the above-mentioned apparatus, employing the following technical solution:

[0020] A method for continuously preparing diethylhydroxylamine using the above-mentioned apparatus, 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 liquid at the outlet end of the horizontal tubular reactor to obtain the diethylhydroxylamine.

[0021] Optionally, 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 injection ports of the horizontal tubular reactor.

[0022] Optionally, the solvent is any one of tetrahydrofuran, 1,4-dioxane, and acetone.

[0023] Optionally, the molar ratio of the diethylamine to the solvent is (1~2):(1~2).

[0024] In one specific embodiment, the molar ratio of diethylamine to the solvent is 1:1.5, 1:2, or 2:1.

[0025] In this application, the solvent is used to dilute diethylamine and prevent excessive oxidation.

[0026] Optionally, the volume ratio of the initial solution to the hydrogen peroxide is (1~7):1.

[0027] Optionally, the volume ratio of the initial solution to the hydrogen peroxide is (2~6):1.

[0028] Optionally, the volume ratio of the initial solution to the hydrogen peroxide is (2.8~5.1):1.

[0029] In one specific embodiment, the volume ratio of the initial solution to the hydrogen peroxide is 2.8:1, 4.4:1, 4.5:1, or 5.1:1.

[0030] In some specific embodiments, the volume ratio of the initial solution to the hydrogen peroxide is (2.8-4.4):1, (2.8-4.5):1, (4.4-4.5):1, (4.4-5.1):1, and (4.5-5.1):1.

[0031] In existing technologies, most methods for preparing diethylhydroxylamine by reacting diethylamine and hydrogen peroxide employ an excess (or equal) amount of hydrogen peroxide compared to diethylamine. This application, however, favors the use of an excess of diethylamine to avoid excessive oxidation of diethylhydroxylamine due to excessive hydrogen peroxide. For example, in Example 1, the actual ratio of diethylamine, hydrogen peroxide, and tetrahydrofuran is 2:1:3.

[0032] Optionally, the continuous preparation temperature of diethylhydroxylamine is 40-60°C.

[0033] Optionally, the continuous preparation temperature of diethylhydroxylamine is 50-60°C.

[0034] Optionally, the continuous preparation temperature of diethylhydroxylamine is 40-50°C.

[0035] In one specific embodiment, the continuous preparation temperature of diethylhydroxylamine is 40°C, 50°C, or 60°C.

[0036] Optionally, the method further includes a post-processing step, specifically: the reaction solution is subjected to distillation 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.

[0037] In summary, this application includes at least one of the following beneficial technical effects:

[0038] This application employs an axial gradient filling method with titanium-silicon molecular sieves: the inlet section is filled with 2-3 mm large-particle-size titanium-silicon molecular sieves, effectively mitigating the intense exothermic reaction caused by high reactant concentrations in the initial stage; the outlet section is filled with 0.5-1 mm small-particle-size titanium-silicon molecular sieves to increase the density of active sites and enhance mass transfer of low-concentration reactants in the later stage. By optimizing the catalyst particle size distribution, the kinetic characteristics of the reactant stream are improved, balancing the system pressure and increasing the effective wetting area of ​​the catalyst.

[0039] Compared with related technologies, the catalyst used in this application has no obvious toxicity and can effectively improve the service life of the catalyst. The staged feeding method of hydrogen peroxide in this application solves the problem of catalyst sintering caused by local overheating in the reaction system. At the same time, the optimized oxidant distribution improves the selectivity of diethylhydroxylamine to over 93%, effectively suppressing the formation of nitrone as an oxidation byproduct.

[0040] The gradient-filled structure of this application effectively inhibits the enrichment of reaction intermediates on the catalyst surface and prolongs the catalyst lifetime. After 500 hours of continuous operation, the selectivity of the catalyst for the target product remains above 97% of the initial selectivity (measured after 3 hours of reaction).

[0041] This application employs a continuous production process to achieve efficient and stable operation of the reaction process, making it suitable for industrial-scale production. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves according to this application. Detailed Implementation

[0043] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment 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 pertains.

[0044] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0045] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0046] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0047] This application provides an apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves.

[0048] The device includes a horizontal tubular reactor, in which titanium-silicon molecular sieve catalyst is filled in an axial three-stage gradient manner along the material flow direction. Specifically: the inlet section is filled with large spherical catalyst particles, which occupy 30% of the length of the horizontal tubular reactor from the material inlet; the particle size of the large spherical catalyst particles is 2 mm < ≤ 3 mm; the middle section is filled with medium-sized catalyst particles, which occupy 30% of the length of the horizontal tubular reactor from the inlet section to the material outlet; the particle size of the medium-sized catalyst particles is 1 mm < ≤ 2 mm; and the outlet section is filled with small-sized catalyst particles, which occupy 40% of the length of the horizontal tubular reactor from the middle section to the material outlet; the particle size of the small-sized catalyst particles is 0.5 mm < ≤ 1 mm.

[0049] 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, to achieve phased replenishment of the oxidant.

[0050] 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 to form a constant temperature cavity for holding and controlling the temperature of the circulating medium.

[0051] This application also provides a method for preparing diethylhydroxylamine using the above-described apparatus.

[0052] 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 liquid at the outlet end of the horizontal tubular reactor to obtain the diethylhydroxylamine.

[0053] The hydrogen peroxide is fed in a segmented manner, namely: pumped into the inlet end of the horizontal tubular reactor and supplemented a second time at the two hydrogen peroxide replenishment ports of the horizontal tubular reactor.

[0054] In addition, 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.

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0056] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0057] The horizontal tubular reactor used in the following embodiments is made of 316L stainless steel, with a length of 1.5m and an inner diameter of 50mm. Its interior is filled with titanium-silicon molecular sieve catalyst in a three-stage axial gradient along the material flow direction: the inlet section (0-30% length) is filled with 2-3mm large spherical catalyst particles, the middle section (30-60% length) is filled with 1-2mm medium-sized catalyst particles, and the outlet section (60-100% length) is filled with 0.5-1mm small-sized catalyst particles.

[0058] The present application will be further described in detail below with reference to embodiments, comparative examples and test results.

[0059] Example 1

[0060] This embodiment provides a horizontal tubular continuous reaction system based on gradient-filled titanium silicate molecular sieves for the synthesis of diethylhydroxylamine. The system includes a feed unit, a gradient-filled tubular reactor, and a product processing unit. The gradient-filled tubular reactor is the apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves as described in this application.

[0061] The raw material feeding unit includes a diethylamine and tetrahydrofuran mixture storage tank and metering pump, and a hydrogen peroxide storage tank and metering pump. The diethylamine and tetrahydrofuran mixture storage tank is made of 316L stainless steel. The product collection unit includes a raw material and solvent recovery system, an extraction and separation system, and a product purification system.

[0062] refer to Figure 1 The gradient-filled tubular reactor is made of 316L stainless steel, with a designed length of 1.5m and an inner diameter of 50mm. The reactor is divided into sections filled with TS-1 titanium silicate molecular sieves: the inlet section (0-0.45m) is filled with large-particle spherical titanium silicate molecular sieves (2mm < particle size of large-particle spherical titanium silicate molecular sieve ≤ 3mm); the middle section (0.45-0.9m) is filled with medium-particle spherical titanium silicate molecular sieves (1mm < particle size of medium-particle spherical titanium silicate molecular sieve ≤ 2mm); and the outlet section (0.9-1.5m) is filled with small-particle spherical titanium silicate molecular sieves (0.5mm < particle size of small-particle spherical titanium silicate molecular sieve ≤ 1mm). A precision filter (0.5μm sintered metal) is also installed at the outlet to intercept titanium silicate molecular sieve powder.

[0063] The gradient-filled tubular reactor has two hydrogen peroxide replenishment ports on its tube wall, located at 0.45m and 0.9m from the reactor inlet, respectively. The injection volume at each port is 25% of the total hydrogen peroxide volume, totaling 50%. The initial hydrogen peroxide injection point is at the reactor inlet, with an injection volume of 50% of the total hydrogen peroxide volume, injected simultaneously with the initial solution preparation. Furthermore, the gradient-filled tubular reactor is externally jacketed, and the jacket and the outer wall of the reaction tube form a constant-temperature cavity for holding the circulating medium.

[0064] The method for preparing diethylhydroxylamine using the above-mentioned gradient-filled tubular reactor (an apparatus for the continuous synthesis of diethylhydroxylamine based on gradient-filled titanium silicate molecular sieves) specifically includes the following steps:

[0065] (1) Mix diethylamine (2 mol) and tetrahydrofuran (3 mol) at a molar ratio of 1:1.5 to obtain the initial solution;

[0066] (2) The initial solution and hydrogen peroxide (concentration of 30%, 1 mol) were pumped into a gradient-packed tubular reactor at a volume ratio of 4.4:1 for oxidation reaction. The hydrogen peroxide was fed in stages, injected three times at 0%, 30%, and 60% of the reactor length, with injection amounts of 50%, 25%, and 25% of the total hydrogen peroxide injection amount, respectively, and the reaction temperature was 50℃.

[0067] (3) Collect the material at the reactor outlet.

[0068] Gas chromatography analysis showed that the selectivity for diethylhydroxylamine was 96%. The utilization rate of hydrogen peroxide was calculated to be 94.6%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 96%, and the water content was less than 2%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 99% of the initial selectivity (measured after 3 hours of reaction).

[0069] Example 2

[0070] This embodiment provides a method for preparing diethylhydroxylamine using an apparatus based on gradient-filled titanium silicate molecular sieves for continuous synthesis. The difference between this embodiment and Example 1 is that acetone is used instead of tetrahydrofuran as the solvent; all other operations remain the same as in Example 1.

[0071] Gas chromatography analysis showed that the selectivity for diethylhydroxylamine was 93.2%. The utilization rate of hydrogen peroxide was calculated to be 92.4%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 3%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 97% of the initial selectivity (measured after 3 hours of reaction).

[0072] Example 3

[0073] This embodiment provides a method for preparing diethylhydroxylamine using an apparatus based on gradient-filled titanium silicate molecular sieves for continuous synthesis. The difference between this embodiment and Example 1 is that the initial solution and hydrogen peroxide are prepared at a volume ratio of 4.5:1, while all other operations remain the same as in Example 1.

[0074] Gas chromatography analysis showed that the selectivity for diethylhydroxylamine was 93.7%. The utilization rate of hydrogen peroxide was calculated to be 92.7%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 3%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 98% of the initial selectivity (measured after 3 hours of reaction).

[0075] Example 4

[0076] This embodiment provides a method for preparing diethylhydroxylamine using an apparatus based on gradient-filled titanium silicate molecular sieves for continuous synthesis. The difference between this embodiment and Example 1 is that the molar ratio of diethylamine (2 mol) to tetrahydrofuran (4 mol) is 1:2; the initial solution and hydrogen peroxide (1 mol) are prepared at a volume ratio of 5.1:1; all other operations are consistent with Example 1.

[0077] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 94.1%. The utilization rate of hydrogen peroxide was calculated to be 92.7%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 96%, and the water content was less than 3%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 99% of the initial selectivity (measured after 3 hours of reaction).

[0078] Example 5

[0079] This embodiment provides a method for preparing diethylhydroxylamine using an apparatus based on gradient-filled titanium silicate molecular sieves for continuous synthesis. The difference between this embodiment and Example 1 is that the reaction temperature is 60°C, while all other operations remain the same as in Example 1.

[0080] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 94.4%. The utilization rate of hydrogen peroxide was calculated to be 93.8%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 3%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 97% of the initial selectivity (measured after 3 hours of reaction).

[0081] Example 6

[0082] This embodiment provides a method for preparing diethylhydroxylamine using an apparatus based on gradient-filled titanium silicate molecular sieves for continuous synthesis. The difference between this embodiment and Example 1 is that the reaction temperature is 40°C, while all other operations remain the same as in Example 1.

[0083] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 93.5%. The utilization rate of hydrogen peroxide was calculated to be 91.9%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 3%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 98% of the initial selectivity (measured after 3 hours of reaction).

[0084] Example 7

[0085] This embodiment provides a method for preparing diethylhydroxylamine using an apparatus based on gradient-filled titanium silicate molecular sieves for continuous synthesis. The difference between this embodiment and Example 1 is that the molar ratio of diethylamine (2 mol) to tetrahydrofuran (1 mol) is 2:1; the volume ratio of the initial solution to hydrogen peroxide (1 mol) is 2.8:1; all other operations are consistent with Example 1.

[0086] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 93.0%. The utilization rate of hydrogen peroxide was calculated to be 92.2%. Unreacted raw materials and solvents were recovered by distillation. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 96%, and the water content was less than 3%. After 500 hours of continuous operation, the catalyst's selectivity for the target product remained above 97% of the initial selectivity (measured after 3 hours of reaction).

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing diethylhydroxylamine using a continuous synthesis apparatus for diethylhydroxylamine via titanium silicate molecular sieves. The difference between this comparative example and Example 1 is that the catalyst is uniformly packed with a single particle size (1-2 mm), and the packing length occupies 100% of the reactor; the hydrogen peroxide is added dropwise at the reactor inlet all at once, while all other operations remain consistent with Example 1.

[0089] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 79.8%. Calculations showed that the utilization rate of hydrogen peroxide was only 78.6%, far lower than that of Example 1 of this application. The reaction solution was subjected to distillation to recover unreacted raw materials and solvents. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 2%. After 500 hours of continuous operation, the selectivity of the catalyst for the target product decreased to 91% of the initial selectivity (measured after 3 hours of reaction).

[0090] Comparative Example 2

[0091] This comparative example provides a method for preparing diethylhydroxylamine using a continuous synthesis apparatus for titanium silicate molecular sieves. The difference between this comparative example and Example 1 is that the catalyst is packed in reverse order of particle size, with the inlet section (0-0.45m) filled with small spherical titanium silicate molecular sieve particles (0.5-1mm), the middle section (0.45-0.9m) filled with medium-sized spherical titanium silicate molecular sieve particles (1-2mm), and the outlet section (0.9-1.5m) filled with large spherical titanium silicate molecular sieve particles (2-3mm). The hydrogen peroxide is added dropwise all at once at the reactor inlet. All other operations are consistent with Example 1.

[0092] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 75.6%. Calculations showed that the utilization rate of hydrogen peroxide was only 73.8%, far lower than that of Example 1 of this application. The reaction solution was subjected to distillation to recover unreacted raw materials and solvents. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 3%. After 500 hours of continuous operation, the selectivity of the catalyst for the target product decreased to 87% of the initial selectivity (measured after 3 hours of reaction).

[0093] Comparative Example 3

[0094] This comparative example provides a method for preparing diethylhydroxylamine using a continuous synthesis apparatus employing titanium silicate molecular sieves. The difference between this comparative example and Example 1 is that the hydrogen peroxide is added dropwise all at once at the reactor inlet. All other operations remain consistent with Example 1.

[0095] Gas chromatography analysis showed that the selectivity of diethylhydroxylamine was 85.7%. Calculations showed that the utilization rate of hydrogen peroxide was only 82.1%, far lower than that of Example 1 of this application. The reaction solution was subjected to distillation to recover unreacted raw materials and solvents. After extraction and separation of the aqueous phase, the organic phase was purified by distillation to obtain the diethylhydroxylamine product. Gas chromatography analysis showed that the purity of diethylhydroxylamine was greater than 95%, and the water content was less than 3%. After 500 hours of continuous operation, the selectivity of the catalyst for the target product decreased to 89% of the initial selectivity (measured after 3 hours of reaction).

[0096] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A device for the continuous synthesis of diethylhydroxylamine based on gradient filling of titanium silicalite, characterized in that, The device comprises a horizontal tubular reactor, which is filled with titanium silicalite molecular sieve 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; Two hydrogen peroxide supplementary injection interfaces are arranged on the pipe wall of the horizontal tubular reactor, respectively at the starting position of the middle section and the starting position of the outlet section, for injecting part of the hydrogen peroxide at the corresponding positions of the gradient-filled catalyst.

2. The apparatus of claim 1, wherein, The horizontal tubular reactor is provided with a jacketed constant temperature system, which forms a constant temperature cavity with the jacket and the outer wall of the horizontal tubular reactor.

3. The apparatus of claim 1, wherein, The titanium silicalite molecular sieve is TS-1 type, and the silicon-titanium molar ratio is 50-80.

4. A method for continuous production of diethylhydroxylamine using the apparatus according to any one of claims 1 to 3, characterized in that, The method specifically comprises the following steps: mixing and preparing diethylamine and a solvent in a certain proportion to obtain a primary solution; pumping the primary 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 diethylhydroxylamine; the hydrogen peroxide is fed in a segmented manner, which is pumped into the inlet end of the horizontal tubular reactor and supplemented and injected twice at the two hydrogen peroxide supplementary injection interfaces of the horizontal tubular reactor.

5. The method of claim 4, wherein, The solvent is any one of tetrahydrofuran, 1,4-dioxane and acetone.

6. The method of claim 4, wherein, The molar ratio of the diethylamine to the solvent is (1-2):(1-2).

7. The method of claim 4, wherein, The volume ratio of the primary solution to the hydrogen peroxide is (1-7):

1.

8. The method of claim 7, wherein, The volume ratio of the primary solution to the hydrogen peroxide is (2.8-5.1):

1.

9. The method of claim 4, wherein, The temperature for the continuous preparation of diethylhydroxylamine is 40-60℃.

10. The method of claim 9, wherein, The temperature for the continuous preparation of diethylhydroxylamine is 50-60℃.

11. The method of claim 4, wherein, 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 diethylhydroxylamine product.

Images