Method for producing N, N-dinitroso pentamethylenetetramine by tubular reaction continuous method
Through the multi-strand feeding technology of the continuous tube reaction method, the continuous production of N,N-dinitrosotpentamethylenetetramine is achieved, solving the problems of high investment, maintenance costs and heat loss in traditional methods, improving yield and purity, and achieving an efficient and safe production process.
Patent Information
- Application Number
- CN202411648673.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-11-15
- Filing Date
- 2024-11-19
- Publication Date
- 2025-02-25
AI Technical Summary
The existing production methods of N,N-dinitrosotpentamethylenetetramine have high investment, maintenance costs and large area, and traditional kettle reactions have thermal losses and dangers, and low yields.
The continuous production of the tube reaction is carried out through multiple feeding methods, including the first-level nitration reaction, the second-level reduction reaction, the third-level nitration reaction and the fourth-level reduction reaction, and the reaction temperature and material ratio are controlled to achieve continuous reaction and stable operation.
The yield and purity of N,N-dinitrosotpentamethylenetetramine was improved, and a yield of 100% was achieved, which reduced the equipment footprint and heat loss, and reduced maintenance costs and labor investment.
Smart Images
Figure CN119504766A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of continuous production, and relates to a method for producing N,N-dinitrosopentamethylenetetramine, and specifically to a method for producing N,N-dinitrosopentamethylenetetramine by a tubular reaction continuous method. Background Art
[0002] N,N-Dinitrosopentamethylenetetramine is mainly used to make sponge rubber and is mostly used in polyvinyl chloride in plastics. The product is heated to decompose into nitrogen and form pores, with large gas emission and high bubbling efficiency. At present, the conventional production method of N,N-Dinitrosopentamethylenetetramine is to use urotropine, sodium nitrite and sulfuric acid as raw materials to generate N,N-Dinitrosopentamethylenetetramine and formaldehyde, then add ammonia water to reduce formaldehyde to generate urotropine, then add sulfuric acid again to continue to generate N,N-Dinitrosopentamethylenetetramine and formaldehyde, and finally add ammonia water to reduce the formaldehyde produced by the reaction, and the reaction ends; finally, the obtained reaction liquid is separated from the waste liquid, washed and dehydrated with water to obtain N,N-Dinitrosopentamethylenetetramine. This method has a large one-time investment, high maintenance cost, and occupies a large area. In addition, the traditional kettle reaction has a large liquid holding volume and a large heat release. The jacket heat transfer capacity of the kettle reaction is low, which poses a certain risk. Continuous production can effectively reduce the liquid holding volume to less than 20%, and can better control the reaction temperature through heat exchange. Moreover, the poor heat exchange capacity results in the traditional kettle yield being only about 75%. Summary of the invention
[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for producing N,N-dinitrosopentamethylenetetramine by a tubular reaction continuous process, so as to improve the yield and purity of N,N-dinitrosopentamethylenetetramine.
[0004] To achieve the above object, the technical solution adopted by the present invention is: a method for continuously producing N,N-dinitrosopentamethylenetetramine, comprising the following steps: (a) First stage nitration reaction: In a continuous reactor, urotropine, sodium nitrite and sulfuric acid are used as raw materials to carry out nitration reaction to generate a first reactant; the reaction temperature of the nitration reaction is -15~10°C; (b) a second stage reduction reaction: the first reactant is subjected to a reduction reaction with the added ammonia water to generate a second reactant; the temperature of the reduction reaction is 0 to 20° C.; (c) a third nitration reaction: the second reactant is subjected to a nitration reaction with added sulfuric acid to generate a third reactant; the reaction temperature of the nitration reaction is 10 to 30° C.; (d) Fourth stage reduction reaction: the third reactant is subjected to a reduction reaction with the added ammonia water to generate a fourth reactant; the reaction temperature of the reduction reaction is 10-30°C.
[0005] Optimally, in step (a), the molar ratio of hexamethylenetetramine, sodium nitrite and sulfuric acid is 1:2~3:0.8~1.2.
[0006] Furthermore, in step (a) and step (c), the mass concentration of the sulfuric acid is independently 30-50%.
[0007] Optimally, in step (b), the molar ratio of the urotropine to the ammonia water is 1:0.8-1.2.
[0008] Furthermore, in step (b) and step (d), the mass concentration of the ammonia water is independently 15% to 30%.
[0009] Optimally, in step (c), the molar ratio of hexamethylenetetramine to sulfuric acid is 1:0.2-0.7.
[0010] Optimally, in step (d), the molar ratio of the urotropine to the ammonia water is 1:0.2-1.0.
[0011] Due to the application of the above technical scheme, the present invention has the following advantages compared with the prior art: the method of producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction method of the present invention has been continuously generated to carry out multiple strands of feeding: the first strand is a mixed solution of urotropine, sodium nitrite and water, the second strand is a 30-50% concentration of sulfuric acid, the third strand is a 15-30% concentration of ammonia water, the fourth strand is a 30-50% concentration of sulfuric acid, and the fifth strand is a 15-30% concentration of ammonia water; continuous production is achieved, stable operation reduces labor input costs, and the yield of N,N-dinitrosopentamethylenetetramine produced by this method can reach 100%. At the same time, compared with the kettle reaction, the equipment occupies a small area, which can reduce heat loss and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 This is a schematic structural diagram of a continuous reactor for continuously producing N,N-dinitrosopentamethylenetetramine according to the present invention; Figure 2 The present invention is a schematic structural diagram of the parts in a continuous reactor for continuously producing N,N-dinitrosopentamethylenetetramine. DETAILED DESCRIPTION
[0013] The preferred embodiments of the present invention will be described in detail below. Example 1
[0014] like Figure 1 The multi-feed column reactor (also referred to as an MCC reactor) shown mainly includes structures such as a reaction tube 1, a stirring assembly 2, and a partitioning disc 3.
[0015] The reaction tube 1 is vertically arranged and cylindrical (the inner diameter and height of the reaction tube 1 can be adjusted according to the reaction time. In the subsequent embodiments, the inner diameter can be set to 40 mm and the height can be set to 500 mm). The stirring assembly 2 includes a stirring shaft 21, a stirring blade 22, and a motor 23, etc.; the stirring shaft 21 is arranged in the reaction tube 1 and extends outside it (that is, the upper end of the stirring shaft 21 extends to the outside of the reaction tube 1); the stirring blade 22 has multiple paths, which are formed on the outer surface of the stirring shaft 21 and are located in the reaction tube 1 (the specific shape and structure of the stirring blade 22 are not limited, as long as the mixing of materials can be achieved; the existing conventional ones can be adopted); the motor 23 is connected to the upper end of the stirring shaft 21 to drive the rotation of the stirring shaft 21. The installation method of the motor 23 adopts the existing conventional method, such as installing a bracket on the top of the reaction tube 1 so that the motor 23 is installed on the bracket; the connection method between the motor 23 and the stirring shaft 21 can be direct connection, gear or belt drive connection, etc., as long as the motor 23 can drive the stirring shaft 21.
[0016] The partition disc 3 is composed of multiple pieces, and in this embodiment, there are three pieces. Each partition disc 3 is mounted on the stirring shaft 21 through a mounting hole 31 at the center (specifically, as shown in FIG. Figure 2 As shown, a mounting hole 31 is provided at the center of the partition disc 3, through which the partition disc 3 and the stirring shaft 21 are tightly connected together, and the mounting method can be interference fit, welding fixation, etc.). Multiple partition discs 3 are arranged at intervals up and down (generally at equal intervals, of course, they can be arranged at unequal intervals according to actual reaction requirements) in the reaction tube 1 to divide the reaction tube 1 into multiple levels of reaction chambers, so that a material flow gap is formed between each partition disc 3 and the inner wall of the reaction tube 1 (it can be seen that the separation here is not completely isolated, and the adjacent two-level reaction chambers are interconnected at the edge; the width of the material flow gap is preferably 0.5~2mm; in order to facilitate standardized generation, it can be set to 1mm in subsequent embodiments). The bottom reaction chamber has multiple feed ports (two in this embodiment), and the other reaction chambers have at least one feed port (usually one); the top reaction chamber also has a discharge port 16 and an exhaust port 17. It can be seen that when there are three partition disks 3, the reaction tube 1 is divided into four-stage reaction chambers; therefore, the four-stage reaction chamber has at least five feed ports, which can realize the feeding of multiple materials (i.e., multi-stream feeding), and can be used to realize the continuous production of certain chemicals (such as N,N-dinitrosopentamethylenetetramine).
[0017] In the present embodiment, the multi-feed column reactor further includes a plurality of insulation modules. The plurality of insulation modules are formed on the outer wall of the reaction tube 1 and correspond one to one with the plurality of reaction chambers; when the reaction chamber is four-stage, the corresponding insulation modules are also four groups. The plurality of insulation modules are defined as the first insulation jacket 4, the second insulation module 5, the third insulation module 6 and the fourth insulation module 7 from bottom to top, the first insulation jacket 4 having a first jacket inlet 41 and a first jacket outlet 42 located above the first jacket inlet 41, the second insulation module 5 having a second jacket inlet 51 and a second jacket outlet 52 located above the second jacket inlet 51, the third insulation jacket 6 having a third jacket inlet 61 and a third jacket outlet 62 located above the third jacket inlet 61, the fourth insulation module 7 having a fourth jacket inlet 71 and a fourth jacket outlet 72 located above the fourth jacket inlet 71; the jacket inlet is used to input the temperature control medium into the insulation jacket, and the jacket outlet is used to output the temperature control medium, which is an existing conventional method.
[0018] In this embodiment, the multi-feed column reactor also includes a plurality of temperature measuring ports arranged on the reaction tube 1 and corresponding one to one with the plurality of insulation modules (the temperature measuring ports can be embedded in the reaction tube 1 or only in the corresponding jackets). The plurality of temperature measuring ports are defined from bottom to top as a first temperature measuring port 101, a second temperature measuring port 102, a third temperature measuring port 103 and a fourth temperature measuring port 104, which are used to cooperate with the insulation modules, thereby accurately controlling the reaction temperature of each level of reaction chamber. Example 2
[0019] This embodiment provides a method for producing N,N-dinitrosopentamethylenetetramine by a tubular reaction continuous process, using the multi-feed column reactor in Example 1 (when the multi-feed column reactor is started, the materials for the primary reaction (urotropine and sulfuric acid) are first introduced; when the liquid level reaches the feed port of the secondary reaction, ammonia water is introduced; then when the mixed liquid reaches the position of the third-level feed port, secondary sulfuric acid is introduced; then when the mixed liquid reaches the position of the fourth-level feed port, secondary ammonia water is introduced, and the feeding is completed. After equilibrium, continuous feeding and continuous discharging are performed), as follows: (a) First stage nitration reaction: Take 400g of urotropine, 512g of sodium nitrite and 1500g of water, dissolve them and precool them (temperature is 0°C) for use (defined as urotropine mixed solution); prepare 35% (mass concentration, dosage is 500g) sulfuric acid and precool it for use (i.e. sulfuric acid solution); after the feed port of the reactor (in Example 1) is connected, start feeding simultaneously (the urotropine mixed solution is injected through the first feed port 11, and the sulfuric acid solution is injected through the second feed port 12) to carry out nitration reaction (temperature is controlled at about 0°C). The feed rate of the urotropine mixed solution is 10-15g / min, and the feed rate of the sulfuric acid solution is 4-6g / min (calculated as sulfuric acid solution, the same below) (the feed rate can fluctuate within this range, which has little effect on the product quality; the same below); (b) Second stage reduction reaction: 5 min after the above reaction, ammonia water is injected once at the third feed port 13 (feed rate 0.5-1.5 g / min) to carry out reduction reaction (control temperature is about 10° C.; in this embodiment,); (c) Third stage nitration reaction: 5 min after the above reaction, sulfuric acid solution (with the same concentration as in step (a), feed rate 1-2 g / min) is injected into the fourth feed port 14 to carry out nitration reaction (control the temperature at about 20°C); (d) Fourth stage reduction reaction: 5 minutes after the previous reaction, inject secondary ammonia water (the same as the primary ammonia water, the feed rate is 0.3-1.5 g / min) into the fifth feed port 153 for reduction reaction (control the temperature at about 20°C); after the material is discharged, continue to run for 60 minutes and then start to receive the material. The obtained reaction liquid is filtered through a suction filtration bottle and then separated into solid and liquid. The obtained filter cake is washed with clean water and filtered again. The filter cake is dried at 40°C to obtain the product N,N-dinitrosopentamethylenetetramine (60.88 g), and the calculated molar yield is 85%. Example 3
[0020] This embodiment provides a method for producing N,N-dinitrosopentamethylenetetramine by a tubular reaction continuous process, which is basically the same as that in Example 2, except that: in step (a), the nitration reaction is controlled at 10°C; in step (b), the reduction reaction temperature is 20°C; in step (c), the nitration reaction is controlled at 30°C; in step (d), the reduction reaction temperature is 30°C; and finally, the molar yield is 61%. Example 4
[0021] This embodiment provides a method for producing N,N-dinitrosopentamethylenetetramine by a tubular reaction continuous process, which is basically the same as that in Example 2, except that: in step (a), the nitration reaction is controlled at -15°C; in step (b), the reduction reaction temperature is 0°C; in step (c), the nitration reaction is controlled at 10°C; in step (d), the reduction reaction temperature is 10°C; and finally, the molar yield is 78%.
[0022] Comparative Example 1 This example provides a method for continuously producing N,N-dinitrosopentamethylenetetramine, which is basically the same as that in Example 2, except that: in step (a), the nitration reaction is controlled at 20°C; in step (b), the reduction reaction temperature is 20°C; in step (c), the nitration reaction is controlled at 30°C; in step (d), the reduction reaction temperature is 30°C; and finally, the molar yield is 40%.
[0023] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process, characterized in that: The following steps are involved: (a) First stage nitration reaction: In a continuous reactor, urotropine, sodium nitrite and sulfuric acid are used as raw materials to carry out nitration reaction to generate a first reactant; the reaction temperature of the nitration reaction is -15~10°C; (b) a second stage reduction reaction: the first reactant is subjected to a reduction reaction with the added ammonia water to generate a second reactant; the temperature of the reduction reaction is 0 to 20° C.; (c) a third nitration reaction: the second reactant is subjected to a nitration reaction with added sulfuric acid to generate a third reactant; the reaction temperature of the nitration reaction is 10 to 30° C.; (d) Fourth stage reduction reaction: the third reactant is subjected to a reduction reaction with the added ammonia water to generate a fourth reactant; the reaction temperature of the reduction reaction is 10-30°C.
2. The method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process according to claim 1, characterized in that: In step (a), the molar ratio of hexamethylenetetramine, sodium nitrite and sulfuric acid is 1:2-3:0.8-1.
2.
3. The method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process according to claim 1 or 2, characterized in that: In step (a) and step (c), the mass concentration of the sulfuric acid is independently 30-50%.
4. The method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process according to claim 1, characterized in that: In step (b), the molar ratio of the urotropine to the ammonia water is 1:0.8-1.
2.
5. The method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process according to claim 1 or 4, characterized in that: In step (b) and step (d), the mass concentration of the aqueous ammonia is independently 15% to 30%.
6. The method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process according to claim 1, characterized in that: In step (c), the molar ratio of hexamethylenetetramine to sulfuric acid is 1:0.2-0.
7.
7. The method for producing N,N-dinitrosopentamethylenetetramine by a continuous tubular reaction process according to claim 1, characterized in that: In step (d), the molar ratio of the urotropine to the ammonia water is 1:0.2-1.0.