Preparation method of pentamethyldiethylenetriamine and airlift reactor

Abstract

The invention provides a preparation method of pentamethyldiethylenetriamine and an airlift reactor, and relates to the technical field of compound synthesis, the preparation method of pentamethyldiethylenetriamine comprises the following steps: providing diethylenetriamine, formaldehyde and a solvent; adding a solvent and a catalyst into the reactor; introducing diethylenetriamine and hydrogen into one end of the reactor, so that the diethylenetriamine and the hydrogen flow from the raw material inlet end of the reactor to the product outlet end; the formaldehyde is added in N sections in the flowing direction of the diethylenetriamine and the hydrogen, so that the diethylenetriamine, the hydrogen and the formaldehyde react at the temperature not higher than 100 DEG C; the invention also provides an airlift reactor applied to the preparation method of pentamethyldiethylenetriamine. According to the preparation method provided by the invention, pentamethyldiethylenetriamine can be prepared at the temperature of 100 DEG C or below.

Description

Technical Field

[0001] The present application relates to the technical field of compound preparation, and in particular to a preparation method of pentamethyldiethylenetriamine and an air-lift reactor. Background Art

[0002] Pentamethyldiethylenetriamine, industry code PC-5, is a commonly used polyurethane foaming agent, especially widely used in the thermal insulation materials of refrigerators. Moreover, in recent years, pentamethyldiethylenetriamine has also begun to be applied in electronic chemicals. Currently, the main production method of pentamethyldiethylenetriamine is the formaldehyde methylation method of diethylenetriamine. This method uses formaldehyde as the methylation reagent and formic acid as the hydrogen donor, and is produced in a reaction kettle. The yield of pentamethyldiethylenetriamine is 86.44%. Due to the low yield of the formaldehyde formic acid method and the difficult treatment of the postpartum wastewater caused by excessive formic acid, it has now been gradually replaced by the formaldehyde hydrogenation method. However, the formaldehyde hydrogenation method requires the use of hydrogen and a catalyst, and the entire reaction system is a gas-liquid-solid ternary system, which poses new requirements for mass transfer and heat transfer. Moreover, in the industrial production process, the hydrogenation ability is not only related to the hydrogen pressure and the catalyst, but also closely related to the equipment. In the industrial production process, a high-pressure kettle is basically used for batch production. The high-pressure kettle occupies a large area, has a small production capacity per unit time, and there is a serious phenomenon of "running, leaking, dripping" on site, which is not conducive to large-scale production. Summary of the Invention

[0003] The purpose of the present application is to provide a preparation method of pentamethyldiethylenetriamine, which strengthens the mass transfer and heat transfer between the gas, liquid and solid materials through the violent flow of gas, and at the same time sets the batch addition of formaldehyde in a specific proportion, reducing the reaction temperature required in the preparation process of pentamethyldiethylenetriamine by hydrogenation.

[0004] The present application also provides an air-lift reactor.

[0005] In the first aspect, in order to solve the above problems, the present application provides a preparation method of pentamethyldiethylenetriamine, including the following steps:

[0006] Provide diethylenetriamine, formaldehyde and a solvent;

[0007] Put the solvent and the catalyst into the reactor;

[0008] Introduce diethylenetriamine and hydrogen into one end of the reactor, and make the diethylenetriamine and hydrogen flow from the raw material inlet end of the reactor to the product outlet end;

[0009] Add formaldehyde in segments in the flow direction of diethylenetriamine and hydrogen, so that the diethylenetriamine, hydrogen and formaldehyde react at a temperature not higher than 100 °C;

[0010] Among them, N is a natural number greater than or equal to 1; let the percentage of the mass of formaldehyde input in each stage in the total amount of formaldehyde input be the formaldehyde addition percentage. In the moving direction of diethylenetriamine and hydrogen, the ratio of the formaldehyde addition percentage in the latter stage to that in the previous stage is 1 / 5 to 1 / 2.

[0011] Furthermore, in some embodiments of the present application, the input amount of formaldehyde in the first stage is not less than 60% of the total amount of formaldehyde input.

[0012] Furthermore, in some embodiments of the present application, the input amount of formaldehyde is 1.00001 to 1.30000 times the theoretical input amount of formaldehyde.

[0013] Furthermore, in some embodiments of the present application, it further includes a catalyst supplementary input process;

[0014] The catalyst is supplementary input from the side of the reactor close to the product outlet; the moving direction of the supplementary input catalyst in the reactor is opposite to the flow direction of the hydrogen.

[0015] Furthermore, in some embodiments of the present application, the formaldehyde is input into the reactor in the form of an aqueous formaldehyde solution; the dosage of the catalyst is 5 to 10% of the total mass of the liquid held in the reactor in terms of mass percentage.

[0016] Furthermore, in some embodiments of the present application, in the reactor, the reaction temperature for reacting diethylenetriamine, hydrogen and formaldehyde is 80 to 100 °C; and / or

[0017] The air pressure in the reactor is 1.0 to 5.0 MPa; and / or

[0018] The space velocity of the hydrogen in the reactor is 40 to 200 Nm 3 / kg of diethylenetriamine; and / or

[0019] The ratio of the input speed of diethylenetriamine in moles per hour to the input speed of formaldehyde in moles per hour is 1:(5 to 5.5).

[0020] Furthermore, in some embodiments of the present application, the preparation method further includes a recycling process; the recycling process includes collecting the hydrogen discharged from the product outlet end of the reactor and adding the collected hydrogen to the reactor from the raw material inlet end of the reactor.

[0021] Furthermore, in some embodiments of the present application, the reactor is an air-lift reactor;

[0022] The diethylenetriamine and hydrogen flow from bottom to top.

[0023] Second aspect, the present application also provides airlift reactor that can be used in the preparation method described in the first aspect, including:

[0024] A reaction section, the reaction section is provided with a reaction chamber, a first feed inlet, a second feed inlet and a plurality of third feed inlets that are sequentially arranged from bottom to top and are all communicated with the reaction chamber; the first feed inlet is used for introducing hydrogen; the second feed inlet is used for feeding diethylenetriamine; a plurality of the third feed inlets are all used for feeding formaldehyde, and a plurality of the third feed inlets are all arranged on the side of the reactor and are sequentially arranged from one end close to the first feed inlet to the end far from the first feed inlet;

[0025] A filtration section, arranged at one end of the reactor away from the first feed inlet, the filtration section includes an inner cavity communicated with the reaction chamber, and a filter for filtering out products is arranged in the inner cavity; the filtration section is provided with a first discharge port and a second discharge port; the first discharge port is used for discharging gas; the second discharge port is used for discharging non-gas.

[0026] Further, in some embodiments of the present application, the filtration section is further provided with a catalyst inlet for introducing a catalyst into the reactor; and / or

[0027] The filtration section is further provided with a gas-liquid separator; the first discharge port is communicated with the gas outlet of the gas-liquid separator; the filter is further provided with a third discharge port; the liquid outlet of the gas-liquid separator is communicated with the third discharge port;

[0028] Further, the reactor further includes a circulation device; one end of the circulation device is connected to the first discharge port, and the other end is connected to the first feed inlet.

[0029] The present application provides a preparation method of pentamethyldiethylenetriamine, which does not adopt high-temperature and high-pressure reaction conditions. During the reaction process, the flow of reaction raw materials is driven by the hydrogen used for hydrogenation, and by setting the specific segmented addition amount of formaldehyde, the raw materials can achieve the reaction to produce pentamethyldiethylenetriamine at a lower reaction temperature and reaction pressure, and continuous preparation can be realized without intermittent high-temperature and high-pressure preparation; moreover, during the preparation process, due to the lower temperature and pressure, the pressure on the catalyst particles is smaller, the breakage rate of the catalyst particles can be reduced, the validity period of the catalyst can be extended, and its service life can be improved; in addition, the competition in the hydrogenation process of primary amines and the hydrogenation process of intermediate secondary amines during the reaction process can be minimized, and the product yield can be improved.

[0030] The present application provides an airlift reactor, which has a simple structure and can be applicable to the preparation process of synthesizing compounds using gas and liquid raw materials; especially applicable to the non-high-temperature and high-pressure preparation process of pentamethyldiethylenetriamine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic flow chart of a preparation method of pentamethyldiethylenetriamine provided in some embodiments of the present application;

[0033] Figure 2 It is a schematic structural diagram of an air-lift reactor for the preparation of pentamethyldiethylenetriamine provided in some embodiments of the present application;

[0034] Figure 3 It is a cross-sectional view of a filtering part of an air-lift reactor for the preparation of pentamethyldiethylenetriamine provided in some embodiments of the present application.

[0035] Main element symbol description:

[0036] 10 - Reaction part, 12 - First feed port, 13 - Second feed port, 14 - Third feed port, 15 - Temperature sensor, 16 - Pressure sensor, 17 - Parking discharge port, 20 - Filtering part, 21 - Inner cavity, 22 - Filter screen, 23 - First discharge port, 24 - Second discharge port, 25 - Catalyst input port, 26 - Outer shell, 27 - Third discharge port. Specific embodiments

[0037] The following will clearly and completely describe the technical solutions of the present application in combination with the embodiments. Obviously, the described embodiments are some embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0038] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "rear", "left", "right", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present application. In addition, the terms "first", "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0039] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0040] During the research and development of the production of pentamethyldiethylenetriamine by the formaldehyde methylation reaction of diethylenetriamine, the applicant found that the temperature and pressure required for the existing formaldehyde methylation reaction of diethylenetriamine to obtain pentamethyldiethylenetriamine are usually relatively high, and it is difficult to obtain pentamethyldiethylenetriamine with a high yield when the reaction temperature is lower than 120 °C. In order to reduce the reaction temperature and reaction pressure, the applicant studied the reaction process and found that: during the methylation of diethylenetriamine, compound 1 is preferentially formed, and at this time, the required hydrogen pressure is relatively low (0.7 - 1.0 Mpa); however, there are three secondary amine structures in the structure of compound 1, but when continuing to methylate to synthesize pentamethyldiethylenetriamine, the required hydrogen pressure is very high (3.0 - 4.0 Mpa), and the required temperature is also relatively high (>120 °C). The specific reaction structural formula is as follows:

[0041]

[0042] In order to clarify the internal reason for the difference in reaction conditions, the applicant studied the mechanism of the formaldehyde methylation of primary amine and secondary amine, and the reaction mechanisms of the two are as follows:

[0043]

[0044] That is, after the primary amine and formaldehyde react, hydroxylamine (same carbon hydroxylamine) is generated. Hydroxylamine is unstable and easily decomposes into primary amine or formaldehyde. It also undergoes a dehydration reaction to generate Schiff base. Schiff base is also an aldimine structure, which is easy to polymerize and easily generate colored products, making the reaction liquid yellow to brown. Therefore, it is necessary to timely add Schiff base and hydrogenate to generate stable methylated products. The hydrogenation process and the polymerization process are a competitive reaction. Therefore, in order to make the hydrogenation process easier, it may be necessary to increase the hydrogenation capacity when the secondary amine reacts to generate pentamethyldiethylenetriamine.

[0045]

[0046] That is, secondary amines react with formaldehyde to generate hydroxylamine (same-carbon hydroxylamine), but the hydroxylamine formed by secondary amines does not have active hydrogen to undergo dehydration reaction. At the same time, the instability of same-carbon hydroxylamines makes it easy to decompose into secondary amines and formaldehyde, forming a balance with low hydroxylamine content. In order to destroy this balance, it is necessary to directly hydrogenate the hydroxyl group to generate water through extremely high hydrogenation capacity, and hydrogenate and crack the generated hydroxylamine into methylated products.

[0047] Therefore, the applicant discovered that primary amines and secondary amines undergo different mechanisms and require different hydrogenation capacities; but coincidentally, both are competing reactions and both need to win the competitive reaction by improving the hydrogenation capacity, which may be one of the key reasons for the higher pressure and temperature required for the preparation of pentamethyldiethylenetriamine.

[0048] Based on this, the applicant proposed a method for preparing pentamethyldiethylenetriamine. In the method, in the reaction raw materials flowing in one direction, by controlling the amount of formaldehyde added in the reactor and the control of the addition position, the hydrogenation competition process of the primary amine and the secondary amine in the reactor is approximately dislocated and the reaction environment is partially superimposed, so that the hydrogenation capacity and reaction conditions required due to the competition are reduced, and the reaction conditions required for the reaction are reduced, so that pentamethyldiethylenetriamine can be produced through the formaldehyde methylation reaction of diethylenetriamine at a lower temperature, and continuous preparation can be achieved in the same reactor. Figure 1 , the preparation method specifically comprises the following steps:

[0049] Provide diethylenetriamine, formaldehyde and solvent;

[0050] Adding a solvent and a catalyst into a reactor;

[0051] Diethylenetriamine and hydrogen are introduced into one end of the reactor so that the diethylenetriamine and hydrogen flow from the raw material inlet end to the product outlet end of the reactor;

[0052] Formaldehyde is fed in segments in the flow direction of diethylenetriamine and hydrogen, so that diethylenetriamine, hydrogen and formaldehyde react at a temperature not higher than 100 °C.

[0053] Wherein, N is a natural number greater than or equal to 1; let the percentage of the mass of formaldehyde fed in each segment in the total amount of formaldehyde fed be the formaldehyde addition percentage. In the moving direction of diethylenetriamine and hydrogen, the ratio of the formaldehyde addition percentage in the latter segment to that in the previous segment is 1 / 5 to 1 / 2.

[0054] It should be noted that the "flow direction of diethylenetriamine and hydrogen" in this application refers to the main flow direction of the fed raw materials diethylenetriamine and hydrogen in the reactor, which is approximately equal to the direction from the hydrogen inlet to the outlet. Since there are pressure and flow rate when hydrogen is introduced into the reactor, in the reactor, diethylenetriamine and formaldehyde are stirred in the solvent by hydrogen and show a tendency to flow towards the product outlet end (close to the hydrogen outlet); during the process of diethylenetriamine and formaldehyde being stirred and carried by hydrogen in the solvent, they react under the action of a catalyst to generate pentamethyldiethylenetriamine, and the generated pentamethyldiethylenetriamine is also carried by the remaining hydrogen and the volatile gaseous solvent towards the product outlet end and flows out at the product outlet end. For the convenience of description below, this direction is named the "first direction".

[0055] "Feeding formaldehyde in segments in the flow direction of diethylenetriamine and hydrogen" in this application means that the reactor is divided into multiple segments according to the feeding of hydrogen, diethylenetriamine and each formaldehyde. Taking the feeding of formaldehyde in four times as an example, the feeding amount of formaldehyde in the first time is 70% of the total feeding amount of formaldehyde, the feeding amount of formaldehyde in the second time is 20% of the total feeding amount of formaldehyde, the feeding amount of formaldehyde in the third time is 7% of the total feeding amount of formaldehyde, and the feeding amount of formaldehyde in the fourth time is 3% of the total feeding amount of formaldehyde; the reactor stage where the inlets of hydrogen and diethylenetriamine are located is the first segment, the formaldehyde inlet for the first feeding of formaldehyde is the second segment, the formaldehyde inlet for the second feeding of formaldehyde is the third segment, the formaldehyde inlet for the third feeding of formaldehyde is the fourth segment, the formaldehyde inlet for the fourth feeding of formaldehyde is the fifth segment, and the reactor stage where the product outlet end is located is the sixth segment; hydrogen flows from the first segment to the sixth segment.

[0056] Therefore, the statement "in the moving direction of diethylenetriamine and hydrogen, the ratio of the percentage of formaldehyde added in the latter stage to the percentage of formaldehyde added in the previous stage is 1 / 5 to 1 / 2" should be understood in this application as follows: the percentage of formaldehyde added in the third stage compared to the total amount of formaldehyde added is 1 / 5 to 1 / 2 of the percentage of formaldehyde added in the second stage compared to the total amount of formaldehyde added; the percentage of formaldehyde added in the fourth stage compared to the total amount of formaldehyde added is 1 / 5 to 1 / 2 of the percentage of formaldehyde added in the third stage compared to the total amount of formaldehyde added; if formaldehyde is added in four stages, the percentage of formaldehyde added in the fifth stage compared to the total amount of formaldehyde added is 1 / 5 to 1 / 2 of the percentage of formaldehyde added in the fourth stage compared to the total amount of formaldehyde added; and so on.

[0057] It should be noted that the length of the entire formaldehyde addition section is not less than 2 / 3 of the reaction length of the entire reactor. That is, in the first direction, the length from the first formaldehyde inlet to the last formaldehyde inlet is not less than 2 / 3 of the length from the hydrogen inlet to the product outlet, and multiple formaldehyde inlets are evenly distributed on the reactor to promote the reaction, improve the yield, and reduce the reaction temperature and the pressure required for the reaction.

[0058] It should be noted that the reactor used in this application is a long cylindrical reactor, that is, the reaction chamber is long cylindrical, hydrogen flows along the reaction chamber, and formaldehyde is added at different positions in the reaction chamber.

[0059] In this application, the applicant adds formaldehyde in multiple stages and controls the proportion of the amount added in each stage in the total amount of formaldehyde added. By adopting this specific formaldehyde addition method, it is unexpectedly found that it can control the hydrogenation competition between primary amines and secondary amines. Thus, even if the reaction temperature and reaction pressure are reduced, it is possible to produce pentamethyldiethylenetriamine through the methylation reaction of diethylenetriamine with formaldehyde. Furthermore, it provides the possibility for the preparation of pentamethyldiethylenetriamine at low temperature (not higher than 100 °C) and low pressure (not higher than 3 MPa), reduces the processing difficulty, and provides the process conditions for the continuous production of pentamethyldiethylenetriamine.

[0060] It should be noted that the solvent is water, which can be pure water, deionized water, ultrapure water, etc.

[0061] In some embodiments, the input amount of formaldehyde in the first stage is not less than 60% of the total input amount of formaldehyde; the input amount of formaldehyde in the last stage is not more than 10% of the total input amount of formaldehyde. Preferably, the input amount of formaldehyde in the first stage is not more than 75% of the total input amount of formaldehyde, and the input amount of formaldehyde in the last stage is not less than 1% of the total input amount of formaldehyde. The input amount of formaldehyde in the first stage of formaldehyde should neither be too high nor too low. The applicant has found that too low or too high input amount of formaldehyde will lead to a decrease in the yield, and it is necessary to increase the reaction temperature and / or reaction pressure. The possible reason may be that too high input amount of formaldehyde will cause the reaction to concentrate around the input port of the first stage of formaldehyde, and the hydrogenation competition of primary amine and secondary amine is obvious, which will lead to an increase in the demand for hydrogenation conditions; while too low input amount of formaldehyde may cause the heat released during the reaction to be too dispersed, resulting in a decrease in local reaction conditions and less reaction initiation, thus leading to a decrease in the yield.

[0062] In some embodiments, the input amount of formaldehyde is 1.00001 - 1.30000 times the theoretical input amount of formaldehyde, preferably 1.03 - 1.07 times. The input amount of formaldehyde can be slightly higher than the theoretical input amount of formaldehyde, without being too high to cause waste of raw materials.

[0063] In some embodiments, it further includes a catalyst supplementary input process;

[0064] The catalyst is supplemented and input from the side of the reactor close to the product outlet; the moving direction of the supplemented catalyst in the reactor is opposite to the flowing direction of the hydrogen.

[0065] In the present application, the catalyst can be any existing catalyst that can catalyze the hydrogenation reaction of diethylenetriamine and formaldehyde to produce pentamethyldiethylenetriamine, such as Raney nickel, Raney copper, Raney cobalt, and metal catalysts supported on different carriers, such as Cu / γ - Al2O3, Ni / γ - Al2O3, Co / SiO2, etc.; preferably Raney nickel, Cu / γ - Al2O3.

[0066] In the present application, the catalyst is usually metal catalyst particles with a mesh number in the range of 100 to 500. After the particles of this type of catalyst are broken, its catalytic effect will decrease significantly, and then it will show inactivity; during the reaction process, the catalyst particles will gradually break and then become inactive. Therefore, in order to maintain the effective catalyst content in the reactor, it is necessary to pay attention to the inactivation of the catalyst during the reaction process and supplement the catalyst in a timely manner.

[0067] Preferably, the reactor is an air-lift reactor; the diethylenetriamine and hydrogen flow from bottom to top. In order to accelerate the mixing of the catalyst and the raw materials and avoid agglomeration of the catalyst particles, the catalyst is supplemented and added from one side of the reactor product outlet (located at the upper part of the air-lift reactor). Under the action of gravity, the catalyst gradually settles. During the settling process, the rising fluid can fully mix the catalyst and the raw materials, avoiding catalyst agglomeration. The broken and ineffective catalysts will move upward with the fluid due to their tiny particle size and then be collected from the product outlet along with the product. During the preparation process, the supplementary amount of the catalyst is determined according to the mass of the collected broken and ineffective catalysts, and the catalyst is supplemented to maintain a dynamic balance of the amount of the catalyst in the reactor.

[0068] In some embodiments, the formaldehyde is fed into the reactor in the form of an aqueous formaldehyde solution, preferably a 37% aqueous formaldehyde solution; the dosage of the catalyst is 5-10% by mass of the total amount of the diethylenetriamine, the solvent, and the aqueous formaldehyde solution fed, preferably 5%-8%; more preferably 5%-6%.

[0069] In some embodiments, in the reactor, the reaction temperature for reacting the diethylenetriamine, hydrogen and formaldehyde is 80-100 °C, preferably 80-90 °C; and / or

[0070] the air pressure in the reactor is 1.0-5.0 MPa, preferably 3.0-4.0 MPa; and / or

[0071] the flow rate of the hydrogen in the reactor is 100-200 standard cubic meters per hour, preferably 120-180 standard cubic meters per hour, more preferably 160 standard cubic meters per hour; and / or

[0072] the ratio of the feeding rate of the diethylenetriamine in moles per hour to the feeding rate of the formaldehyde in moles per hour is 1:(5-5.5), preferably 1:(5-5.15).

[0073] In some embodiments, the preparation method further includes a recycling process; the recycling process includes collecting the hydrogen discharged from the product outlet end of the reactor and adding the collected hydrogen to the reactor from the raw material inlet end of the reactor.

[0074] Further, the hydrogen also undergoes a pressurization and temperature control process before being recycled and added to the reactor, so that the air pressure and temperature of the hydrogen recycled into the reactor are close to the air pressure and temperature in the reactor.

[0075] In a second aspect, the present application also provides an air-lift reactor that can be used in the preparation method described in the first aspect, including:

[0076] A reaction section, wherein the reaction section is provided with a reaction chamber, a first feed inlet, a second feed inlet, and a plurality of third feed inlets that are arranged in sequence from bottom to top and are all communicated with the reaction chamber; the first feed inlet is used for introducing hydrogen; the second feed inlet is used for feeding diethylenetriamine; the plurality of third feed inlets are all used for feeding formaldehyde, and the plurality of third feed inlets are all arranged on the side surface of the reactor and are arranged in sequence from one end close to the first feed inlet to the end far from the first feed inlet;

[0077] A filtering section, which is arranged at one end of the reactor far from the first feed inlet. The filtering section includes an inner cavity 21 communicated with the reaction chamber, and a filter for filtering out products is arranged in the inner cavity 21; the filtering section is provided with a first discharge port and a second discharge port; the first discharge port is used for discharging gas; the second discharge port is used for discharging non-gas.

[0078] The filtering section includes a housing and a separation chamber arranged inside the housing; the inner diameter of the separation chamber is larger than the inner diameter of the reaction chamber of the reactor, and the separation chamber and the reaction chamber are connected by a funnel-shaped conical side wall; this causes the air pressure of the fluid entering the separation chamber to drop. A product outlet is arranged on the funnel-shaped conical side wall of the separation chamber; an annular filter membrane is arranged inside the separation chamber; the diameter of the filter membrane is larger than the inner diameter of the reaction chamber of the reactor, and the filter membrane does not cover the product outlet, so that the broken catalyst particles and products in the discharged fluid can be enriched through the filter membrane and then discharged through the product outlet below. A filtering chamber is formed between the filter membrane and the housing, and the filtering chamber is communicated with a discharge port for discharging the gas-phase fluid filtered by the filter membrane.

[0079] The filtering section can also be provided with a dryer, which is communicated with the discharge port to remove water vapor from the discharged gas-phase fluid to obtain dry hydrogen. If the hydrogen is recycled, it can also be recycled without drying.

[0080] In some embodiments, the filtering section is also provided with a liquid level detection device, a temperature detection device, a pressure detection device, etc. located in the upper part of the separation chamber; the liquid level detection device is used for detecting the fluid level in the separation chamber to prevent flooding; the temperature detection device is used for detecting the temperature inside the filtering section, and the pressure detection device is used for detecting the air pressure in the filtering section.

[0081] In some embodiments, a pressure detection device and a temperature detection device are arranged near each feed inlet, that is, a pressure detection device and a temperature detection device are arranged at the inlet for hydrogen, the inlet for feeding diethylenetriamine, and each inlet for formaldehyde, for real-time monitoring of the temperature and air pressure in the reactor to facilitate control of the reaction process.

[0082] In some embodiments, the filtering section is also provided with a catalyst inlet for introducing a catalyst into the reactor.

[0083] The filtering part is further provided with a gas-liquid separator; the first discharge port is communicated with the gas outlet of the gas-liquid separator; the filter is further provided with a third discharge port; the liquid outlet of the gas-liquid separator is communicated with the third discharge port.

[0084] Further, the reactor further includes a circulation device; one end of the circulation device is connected to the first discharge port, and the other end is connected to the first feed port.

[0085] Wherein, the circulation device includes a circulation pipeline and a compressor and a heat exchanger arranged on the circulation pipeline; one end of the circulation pipeline is connected to the first discharge port, and the other end is connected to the first feed port, so that the hydrogen after the reaction can enter the compressor through the circulation pipeline, be compressed by the compressor to be close to the air pressure in the reactor, then enter the heat exchanger to control the temperature of the compressed hydrogen to be close to the temperature in the reactor, and then return to the reactor through the circulation pipeline.

[0086] In some other embodiments, a gas distribution plate located in the reaction chamber is further provided at the hydrogen inlet, and a plurality of uniformly arranged hydrogen outlets are provided on the gas distribution plate to enable uniform input in the reaction chamber.

[0087] In some embodiments, a parking discharge port is further provided near the hydrogen inlet for discharging all the materials in the reactor when the reactor stops.

[0088] In some embodiments, a plurality of sampling ports may further be provided on the side wall of the reaction chamber of the reactor for real-time sampling and detection during the reaction process.

[0089] For the convenience of those skilled in the art to better understand the innovative points of the present application, the technical solutions of the present application will be further described in detail below in conjunction with embodiments. The embodiments of the present application described in detail below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application.

[0090] The reactors used in the following examples and comparative examples are all Figure 2 、 Figure 3The reactor shown in [description]; the reactor includes a reaction section 10 for gas-lift reaction, a filtration section 20 for separating the materials after reaction in the reaction section 10, and a circulation device (not shown in the figure) for returning part of the unreacted materials, such as hydrogen, back to the reaction section 10. The reaction section 10 is provided with a first feed inlet 12 for introducing hydrogen (connected to the circulation device to facilitate the recycling of unreacted hydrogen into the reaction chamber of the reaction section), a second feed inlet 13 for introducing diethylenetriamine, and a plurality of third feed inlets 14 for introducing formaldehyde. The first feed inlet 12 is located at the bottommost part of the reaction chamber provided in the reaction section 10, and a hydrogen gas distribution plate (not shown in the figure) is provided in the reaction chamber. The hydrogen gas distribution plate is a plurality of nested annular gas distribution pipes, and each gas distribution pipe is provided with a number of gas distribution holes for gas distribution. The second feed inlet 13 is located above the first feed inlet 12 and below the lowermost third feed inlet 14. The plurality of third feed inlets are arranged in sequence from bottom to top. In this embodiment, the distance between adjacent third feed inlets is the same. Control valves are provided on the first feed inlet, the second feed inlet, and the third feed inlet to control the flow rate of the introduced materials. At the same time, temperature sensors 15 and pressure sensors 16 connected to an external power supply are provided near the second feed inlet and the third feed inlet to continuously monitor the reaction temperature and reaction pressure in the reactor. A stop discharge port 17 is also provided at a position near the first feed inlet below the reaction section for discharging all the materials in the reactor when the reactor stops.

[0091] The reaction section 10 and the filtration section 20 are connected by a flange. The materials after the reaction enter the filtration section 20 along with the rising hydrogen. The filtration section 20 includes a housing 26 and an annular filter screen 22 disposed inside the housing 26 and coaxial with the reaction chamber and having a diameter larger than the material inlet of the filtration section, so that a frustum-shaped inclined wall with a larger upper part and a smaller lower part is formed below the filtration section 20, which can enrich the ineffective catalyst particles in this area; a second discharge port 24 is provided at the lower part of this inclined wall; a material collection space is provided between the housing of the filtration section and the filter screen, and a third discharge port 27 communicating with the material collection space is provided on the housing at the same time; meanwhile, this material collection space can also be used to observe the liquid level of the material in the reactor to avoid overflowing the column. In addition, a first discharge port 23 and a catalyst inlet 25 for injecting the catalyst are provided at the upper part of the filtration section, and the catalyst inlet 25 and the first discharge port 23 are both correspondingly provided inside the ring of the annular filter screen 22. The filtration section is also provided with a gas-liquid separator (not shown in the figure), and the first discharge port and the third discharge port are both communicated with the inlet of the gas-liquid separator, and the gas and liquid are separated by the gas-liquid separator, and the gas is recycled into the reaction chamber through the circulation device. The circulation device includes a heat exchanger sequentially connected to a gas compressor, and the gas separated by the gas-liquid separator enters the reaction chamber through the gas compressor and the heat exchanger in sequence. It should be noted that the devices such as the gas-liquid separator, gas compressor, heat exchanger, sensor, filter screen, control valve, etc. adopted in this application are all prior arts, so their specific structures and models are not described in detail in this application, which does not affect those skilled in the art to understand and implement the solution required to be protected by this application.

[0092] Example 1

[0093] Add 94L of pure water to the reactor, take 9.4 kg (about 10% of the total mass of the liquid in the reaction section) of Raney nickel (purchased from Xunkai Catalyst Co., Ltd., model: RaneCAT-8300, particle size about 70 μm), add it from the catalyst addition port, heat up to 80 °C, fill the reactor with hydrogen, make the air pressure stable at 4.0 Mpa, turn on the hydrogen compressor, and inject hydrogen at a flow rate of 160 standard cubic meters per hour to lift the catalyst in the reaction section in water;

[0094] Pass diethylenetriamine into the reactor at a flow rate of 2.97 kg / h, and at the same time pass 37% aqueous formaldehyde solution from formaldehyde inlet 1 at a flow rate of 8.0 kg / h, pass 37% aqueous formaldehyde solution from formaldehyde inlet 2 at a flow rate of 3.0 kg / h, and pass 37% aqueous formaldehyde solution from formaldehyde inlet 3 at a flow rate of 1.0 kg / h (the molar ratio of diethylenetriamine to formaldehyde is 1:5.13), keep the temperature constant and react continuously for 7 h, take a part of the product at the product outlet, and after solid-liquid separation (removing the ineffective catalyst), take the liquid phase for gas chromatography analysis, and the test results are shown in Table 1.

[0095] Example 2

[0096] Add 94 L of pure water into the reactor. Take 4.7 kg (about 5% of the total mass of the feed liquid in the reaction section) (purchased from Xunkai Catalyst Co., Ltd., model: RaneCAT-8300, particle size about 70 μm) and add it from the catalyst addition port. Heat up to 80 °C, fill the reactor with hydrogen, make the air pressure stable at 5.0 Mpa, turn on the hydrogen compressor, and inject hydrogen at a flow rate of 200 standard cubic meters per hour to make the catalyst in the reaction section float in water;

[0097] Feed diethylenetriamine into the reactor at a flow rate of 2.97 kg / h. At the same time, feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 1 at a flow rate of 9.0 kg / h, feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 2 at a flow rate of 2.0 kg / h, and feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 3 at a flow rate of 1.0 kg / h (the molar ratio of diethylenetriamine to formaldehyde is 1:5.13). Keep the temperature constant and react continuously for 7 h. Take a part of the product at the product outlet, and after solid-liquid separation (removing the deactivated catalyst), take the liquid phase for gas chromatography analysis. The test results are shown in Table 1.

[0098] Example 3

[0099] This example is different from Example 2 in that hydrogen is injected at a flow rate of 160 standard cubic meters per hour, the flow rate of the aqueous formaldehyde solution fed from Formaldehyde Inlet 3 is 0.7 kg / h, and in addition, 37% aqueous formaldehyde solution is fed from Formaldehyde Inlet 4 at a flow rate of 0.3 kg / h (the molar ratio of diethylenetriamine to formaldehyde is 1:5.13). The remaining steps are the same as those in Example 1.

[0100] Keep the temperature constant and react continuously for 7 h. Take a part of the product at the product outlet, and after solid-liquid separation (removing the deactivated catalyst), take the liquid phase for gas chromatography analysis. The test results are shown in Table 1.

[0101] Example 4

[0102] This example is different from Example 3 in that diethylenetriamine is fed at a flow rate of 3.50 kg / h. At the same time, feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 1 at a flow rate of 10.0 kg / h, feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 2 at a flow rate of 3.5 kg / h, feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 3 at a flow rate of 0.7 kg / h, and feed 37% aqueous formaldehyde solution from Formaldehyde Inlet 4 at a flow rate of 0.3 kg / h (the molar ratio of diethylenetriamine to formaldehyde is 1:5.25). The remaining steps are the same as those in Example 1.

[0103] Keep the temperature constant and react continuously for 7 h. Take a part of the product at the product outlet, and after solid-liquid separation (removing the deactivated catalyst), take the liquid phase for gas chromatography analysis. The test results are shown in Table 1.

[0104] Example 5

[0105] Compared with Example 1, the difference in this example is that hydrogen is charged into the reactor to make the air pressure stable at 1.0 Mpa, the reaction system in the reactor is heated to 100 °C, and the reaction is carried out under insulation. The remaining steps are the same as those in Example 1.

[0106] The reaction is continuously carried out under insulation for 7 h. Part of the product is taken at the product outlet, and after solid-liquid separation (removing the ineffective catalyst), the liquid phase is taken for gas chromatography analysis. The detection results are shown in Table 1.

[0107] Comparative Example 1

[0108] Before the reaction starts, 94 L of pure water is introduced into the reactor. 9.4 kg (about 10% of the total mass of the feed liquid in the reaction section) of Raney nickel (purchased from Xunkai Catalyst Co., Ltd., model: RaneCAT-8300, particle size about 70 μm) is added from the catalyst addition port, heated to 80 °C, hydrogen is added to make the pressure in the reaction chamber filled to 4.0 Mpa, the hydrogen compressor is turned on to ensure that the hydrogen flow rate is about 160 Nm³ / h, and the catalyst particles in the reaction section are kept suspended in water; diethylenetriamine is introduced at a flow rate of 2.97 kg / h, and at the same time, 37% aqueous formaldehyde solution is introduced from Formaldehyde Inlet 1 at a flow rate of 11.70 kg / h (the molar ratio of diethylenetriamine to formaldehyde is 1:5).

[0109] The reaction is continuously carried out under insulation for 7 h. Part of the product is taken at the product outlet, and after solid-liquid separation (removing the ineffective catalyst), the liquid phase is taken for gas chromatography analysis. The detection results are shown in Table 1.

[0110] Comparative Example 2

[0111] Before the reaction starts, 94 L of pure water is introduced into the reactor, and then 9.4 kg (about 10% of the total mass of the feed liquid in the reaction section) of catalyst is added from the catalyst addition port, heated to 80 °C, the hydrogen pressure is filled to 4.0 Mpa, the hydrogen compressor is turned on to ensure that the hydrogen flow rate is about 160 Nm³ / h, and the catalyst in the reaction section is kept suspended in water. Then diethylenetriamine is introduced at a flow rate of 2.97 kg / h, and at the same time, 37% aqueous formaldehyde solution is introduced from Formaldehyde Inlet 1 at a flow rate of 6.0 kg / h, and 37% aqueous formaldehyde solution is introduced from Formaldehyde Inlet 2 at a flow rate of 6.0 kg / h (the molar ratio of diethylenetriamine to formaldehyde is 1:5.13).

[0112] The reaction is continuously carried out under insulation for 7 h. Part of the product is taken at the product outlet, and after solid-liquid separation (removing the ineffective catalyst), the liquid phase is taken for gas chromatography analysis. The detection results are shown in Table 1.

[0113] Table 1

[0114]

[0115] As can be seen from Table 1, for the preparation method of pentamethyldiethylenetriamine provided in this application, the product selectivity is good, the generation amount of other intermediates is less, and the product impurities are lower.

[0116] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A preparation method of pentamethyldiethylenetriamine, characterized in that, Comprising the following steps: Providing diethylenetriamine, formaldehyde, and a solvent; Charging the solvent and a catalyst into a reactor; Introducing diethylenetriamine and hydrogen into one end of the reactor, such that the diethylenetriamine and hydrogen flow from the raw material inlet end of the reactor to the product outlet end; Charging formaldehyde in N segments in the flowing direction of the diethylenetriamine and hydrogen, such that the diethylenetriamine, hydrogen, and formaldehyde react at a temperature not higher than 100 °C; Wherein, N is a natural number greater than or equal to 1; let the percentage of the mass of the formaldehyde charged in each segment in the total amount of the charged formaldehyde be the formaldehyde addition percentage. In the moving direction of the diethylenetriamine and hydrogen, the ratio of the formaldehyde addition percentage in the latter segment to the formaldehyde addition percentage in the previous segment is 1 / 5 to 1 / 2.

2. The preparation method of pentamethyldiethylenetriamine according to claim 1, characterized in that, The first charging amount of the formaldehyde is not less than 60% of the total amount of the charged formaldehyde.

3. The preparation method of pentamethyldiethylenetriamine according to claim 1, characterized in that, The charging amount of the formaldehyde is 1.00001 to 1.30000 times the theoretical charging amount of the formaldehyde.

4. The preparation method of pentamethyldiethylenetriamine according to claim 1, characterized in that, It further includes a catalyst supplementary charging process; The catalyst is supplementary charged from the side of the reactor close to the product outlet; the moving direction of the supplementary charged catalyst in the reactor is opposite to the flowing direction of the hydrogen.

5. The preparation method of pentamethyldiethylenetriamine according to claim 4, characterized in that, The formaldehyde is charged into the reactor in the form of an aqueous formaldehyde solution; the dosage of the catalyst is 5 to 10% by mass of the total mass of the liquid held in the reactor.

6. The preparation method of pentamethyldiethylenetriamine according to claim 1, characterized in that, In the reactor, the reaction temperature for the reaction of the diethylenetriamine, hydrogen, and formaldehyde is 80 to 100 °C; and / or The air pressure in the reactor is 1.0 to 5.0 MPa; and / or The space velocity of the hydrogen in the reactor is 40 to 200 standard cubic meters per kilogram of diethylenetriamine; and / or The ratio of the charging rate of the diethylenetriamine in moles per hour to the charging rate of the formaldehyde in moles per hour is 1:(5 to 5.5).

7. The preparation method of pentamethyldiethylenetriamine according to any one of claims 1 to 6, characterized in that, It further includes a recycling process; the recycling process includes collecting the hydrogen discharged from the product outlet end of the reactor and adding the collected hydrogen to the reactor from the raw material inlet end of the reactor.

8. The preparation method of pentamethyldiethylenetriamine according to any one of claims 1 to 6, characterized in that, The reactor is a gas-lift reactor; The diethylenetriamine and hydrogen flow from bottom to top.

9. An air-lift reactor, applicable to the preparation method of pentamethyldiethylenetriamine according to any one of claims 1 to 8, characterized in that, Comprising: A reaction section, the reaction section is provided with a reaction chamber and a first feed port, a second feed port, and a plurality of third feed ports that are sequentially arranged from bottom to top and are all communicated with the reaction chamber; the first feed port is used for introducing hydrogen; the second feed port is used for charging diethylenetriamine; a plurality of the third feed ports are all used for charging formaldehyde, and a plurality of the third feed ports are all arranged on the side of the reactor and are sequentially arranged from the end close to the first feed port to the end far from the first feed port; A filtering section, arranged at the end of the reactor far from the first feed port, the filtering section includes an inner cavity communicated with the reaction chamber, and a filter for filtering out the product is arranged in the inner cavity; the filtering section is provided with a first discharge port and a second discharge port; the first discharge port is used for discharging gas; the second discharge port is used for discharging non-gas.

10. The airlift reactor according to claim 9, characterized in that, The filtering section is further provided with a catalyst feed port for feeding the catalyst into the reactor; and / or The filtering section is further provided with a gas-liquid separator; the first discharge port is communicated with the gas outlet of the gas-liquid separator; the filter is further provided with a third discharge port; the liquid outlet of the gas-liquid separator is communicated with the third discharge port. Further, the reactor further includes a circulation device; one end of the circulation device is connected to the first discharge port, and the other end is connected to the first feed port.

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