A system for separating catalyst from a caprolactam ammoximation reaction slurry
By using catalyst settling separators and toluene extraction technology, the problem of catalyst deactivation has been solved, achieving efficient catalyst recovery and resource conservation, simplifying the operation process, and reducing costs and safety risks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FUJIAN EVERSUN TECH CO LTD
- Filing Date
- 2025-08-08
- Publication Date
- 2026-07-07
AI Technical Summary
In the existing technology, the catalyst is easily deactivated during the caprolactam ammonoximation reaction, which leads to catalyst waste and increased filtration pressure difference, requiring frequent replacement and cleaning, resulting in resource waste and operational complexity.
By employing equipment such as catalyst settling tanks, mixers, and catalyst separators, and using toluene extraction and static separation technologies, undamaged fresh catalysts are separated and recovered, reducing catalyst waste.
It effectively separates large catalyst particles, reduces catalyst waste, simplifies operation procedures, lowers material and labor costs, improves efficiency, and eliminates safety hazards.
Smart Images
Figure CN224462312U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of chemical system technology, and in particular to a system for separating catalysts in a turbid liquid during caprolactam ammonoxime reaction. Background Technology
[0002] Caprolactam (CPL) is an important monomer for the production of nylon 6 fiber and nylon-6 engineering plastics, possessing excellent thermal stability, processability, mechanical properties, and chemical resistance. Cyclohexanone oxime, as a key intermediate in the formation of caprolactam, is produced using advanced ammoniation oxime technology. With tert-butanol as the solvent, cyclohexanone, gaseous ammonia, and hydrogen peroxide are reacted with titanium silicate molecular sieves for cyclohexanone oxime production, achieving a conversion and selectivity of over 99.9%. After purification, the cyclohexanone oxime undergoes a Beckmann rearrangement reaction with fuming sulfuric acid in a rearrangement reactor to generate caprolactam.
[0003] Currently, the ammonium oxime reaction uses titanium silicate molecular sieves as a carrier. During the reaction, the large molecular weight heavy byproducts generated by the reaction block the micropore structure of the catalyst, causing catalyst deactivation. In addition, as the reaction is mixed under the action of stirrers, some large particles of fresh catalyst break down, causing the loss of framework Ti and further deactivating the catalyst. Depending on the reaction conversion rate, color, etc., fresh catalyst needs to be added periodically to maintain the reaction. However, long-term addition causes the membrane filtration pressure difference to rise, requiring the periodic removal of part or all of the catalyst reaction turbidity for cleaning. The reaction turbidity contains most of the deactivated catalyst and the added fresh catalyst. Then, the catalyst is added periodically or the entire reactor is replaced with new catalyst. Generally, external ceramic membrane filtration systems need to be shut down and the entire reactor replaced with fresh catalyst every 6-8 months. For internal metal membrane systems, depending on the reaction conditions, a portion of the liquid level needs to be reduced periodically during operation, and then fresh catalyst needs to be added.
[0004] The existing processing flow is as follows: The deactivated catalyst reaction turbidity is fed into a catalyst settling and separation tank. The reaction turbidity is a mixture of solid and liquid containing 3-6% catalyst, 20% cyclohexanone oxime, 35-40% tert-butanol, 35-38% water, and 3% ammonia. Then, tert-butanol is added to the catalyst settling and separation tank for alcohol washing. When the cyclohexanone oxime content is less than 0.5%, the alcohol washing is stopped. Demineralized water is added to the catalyst settling and separation tank for water washing. When the tert-butanol content is less than 0.2%, the water washing is stopped. During the washing process, the catalyst is repeatedly circulated through a ceramic membrane module for backwashing and filtration. The washing liquid enters the tert-butanol recovery system for recycling. After the catalyst is cleaned to a qualified standard, it enters a plate and frame filter press for filtration. The resulting filter cake is recycled.
[0005] Currently, during the cleaning process of deactivated catalysts, a large amount of fresh catalyst added later is removed from the oxime reactor along with a portion or the entire reactor of the turbid reaction liquid, and then treated as solid waste, resulting in a significant waste of catalyst. Utility Model Content
[0006] To address the aforementioned problems in the prior art, this invention provides a system for separating the catalyst from the turbid liquid of the caprolactam ammoxime reaction, thereby recovering the catalyst and reducing catalyst waste.
[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0008] In a first aspect, this utility model provides a system for separating a catalyst from a turbid solution in a caprolactam ammoniation reaction, comprising a catalyst settling tank, an angle valve, a settling separation pump, a mixer, and a catalyst separator. The feed end at the top of the catalyst settling tank is used to receive the turbid reaction solution. The discharge end at the bottom of the catalyst settling tank is connected to the feed end of the settling separation pump through the angle valve. The discharge end of the settling separation pump is connected to the feed end of the mixer. The discharge end of the mixer is connected to the feed end in the middle of the catalyst separator. The discharge end at the bottom of the catalyst separator is used to discharge the slurry containing the catalyst.
[0009] The mixer is also equipped with a toluene inlet, and the catalyst separator is equipped with a lower sight glass.
[0010] The beneficial effects of this invention are as follows: when the catalyst aqueous solution discharged from the catalyst settling and separation tank is mixed with toluene in the pre-mixer of the catalyst separator and then enters the catalyst separator, the large particles of undamaged new catalyst quickly settle to the bottom, thereby effectively separating the fresh large particles of catalyst added later from the discharged waste catalyst, so as to recover the catalyst and reduce the waste of catalyst.
[0011] Optionally, the catalyst settling and separation tank is provided with a tank wall sight glass and a drain outlet at the same height as the tank wall sight glass.
[0012] Optionally, the catalyst settling tank is equipped with a settling and separation agitator and a first demineralized water inlet at the top.
[0013] Optionally, it also includes a discharge sight glass and a rotary discharge valve. The upper and middle parts of the catalyst separator are respectively provided with an upper sight glass and a middle sight glass. The mixer is also provided with a second demineralized water inlet.
[0014] The discharge end at the bottom of the catalyst separator is connected in sequence to the discharge sight glass and the rotary discharge valve. The discharge end of the rotary discharge valve is connected to the oxime reaction vessel and the inlet end of the sedimentation separation pump. The discharge end of the sedimentation separation pump is also connected to the return end at the top of the catalyst sedimentation separation tank.
[0015] Control valves are provided between the discharge end of the rotary discharge valve and the oxime reactor, between the discharge end of the rotary discharge valve and the inlet end of the sedimentation separation pump, between the discharge end of the sedimentation separation pump and the inlet end of the mixer, and between the discharge end of the sedimentation separation pump and the return end at the top of the catalyst sedimentation separation tank.
[0016] Optionally, the catalyst separator has two symmetrically arranged feed ends, and an inverted L-shaped baffle is arranged inside the catalyst separator above the feed ends.
[0017] Optionally, a grid plate is provided inside the catalyst separator above the baffle plate.
[0018] Optionally, the catalyst separator is further provided with an overflow port at the top, which is used to connect to an extraction tank.
[0019] Optionally, the discharge end of the sedimentation separation conveying pump is also connected to a filter press pipe, and a control valve is also provided on the filter press pipe. The filter press pipe is used to connect the waste catalyst filter press process. Attached Figure Description
[0020] Figure 1 This is an overall schematic diagram of a system for separating a catalyst in a turbid solution of caprolactam ammoxime reaction according to an embodiment of the present invention;
[0021] Explanation of reference numerals in the attached figures:
[0022] 1. Catalyst settling tank; 11. Tank wall sight glass; 12. Settling agitator;
[0023] 2. Angle valve;
[0024] 3. Sedimentation and separation pump;
[0025] 4. Mixer;
[0026] 5. Catalyst separator; 51. Upper sight glass; 52. Middle sight glass; 53. Lower sight glass; 54. Baffle plate; 55. Grating plate.
[0027] 6. Material removal sight glass;
[0028] 7. Rotary discharge valve;
[0029] 8. Control valve;
[0030] 9. Filter press tube;
[0031] 100. Reaction liquid recovery tank; 200. Extraction tower; 300. Extraction tank; 400. Oxime reaction vessel. Detailed Implementation
[0032] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.
[0033] Example 1
[0034] Please refer to Figure 1 A system for separating catalysts from a turbid solution in a caprolactam ammoxime reaction includes a catalyst settling tank 1, an angle valve 2, a settling separation pump 3, a mixer 4, a catalyst separator 5, a discharge sight glass 6, a rotary discharge valve 7, and a filter press 9.
[0035] like Figure 1 As shown, the catalyst settling separator 1 is equipped with a tank wall sight glass 11, a settling separator agitator 12, a drain outlet at the same height as the tank wall sight glass 11, and a first demineralized water inlet at the top. The mixer 4 is equipped with a toluene inlet and a second demineralized water inlet. The catalyst separator 5 is equipped with an upper sight glass 51, a middle sight glass 52, and a lower sight glass 53 at its upper, middle, and lower parts. Inside the catalyst separator 5, an inverted L-shaped baffle plate 54 is arranged above the feed end, a grid plate 55 is arranged above the baffle plate 54, and an overflow port is also provided at the top. The overflow port is used to connect to the extraction tank 300. The catalyst separator 5 has two symmetrically arranged feed ends, so that the material enters from both sides and forms a baffle.
[0036] like Figure 1As shown, the feed end at the top of the catalyst settling separator 1 is used to receive the reaction turbid liquid. The drain outlet of the catalyst settling separator 1 is connected in sequence to the reaction clear liquid recovery tank 100 and the extraction tower 200, which are used for the subsequent tert-butanol recovery process and wastewater process, respectively. The discharge end at the bottom of the catalyst settling separator 1 is connected to the feed end of the settling separation conveying pump 3 through the angle valve 2. The discharge end of the settling separation conveying pump 3 is connected to the feed end of the filter press pipe 9 and the mixer 4, respectively. The filter press pipe 9 is used to connect to the waste catalyst filter press process. The discharge end of the mixer 4 is connected to the feed end in the middle of the catalyst separator 5. The discharge end at the bottom of the catalyst separator 5 is connected in sequence to the discharge sight glass 6 and the rotary discharge valve 7. The discharge end of the rotary discharge valve 7 is connected to the feed end of the oxime reaction vessel 400 and the settling separation conveying pump 3, respectively. The discharge end of the settling separation conveying pump 3 is also connected to the return end at the top of the catalyst settling separator 1.
[0037] like Figure 1 As shown, control valves 8 are installed between the discharge end of the rotary discharge valve 7 and the oxime reactor 400, between the discharge end of the rotary discharge valve 7 and the inlet end of the sedimentation separation conveying pump 3, between the discharge end of the sedimentation separation conveying pump 3 and the inlet end of the mixer 4, between the discharge end of the sedimentation separation conveying pump 3 and the return end at the top of the catalyst sedimentation separation tank 1, and on the filter press pipe 9. These control valves are used to control the opening and closing of each pipeline and realize the switching of different processes.
[0038] The working process of this embodiment is described as follows:
[0039] (1) Static separation: Check and close angle valve 2, and put the reaction turbid liquid containing catalyst into catalyst settling separation tank 1. The reaction turbid liquid is a mixture of reaction solid and liquid containing 3-6% catalyst, 20% cyclohexanone oxime, 35-40% tert-butanol, 35-38% water and 3% ammonia.
[0040] When the catalyst settling separator 1 reaches a certain liquid level, the catalyst-containing turbid reaction liquid is allowed to settle in the catalyst settling separator 1. The sedimentation is observed through the sight glass 11 on the tank wall of the catalyst settling separator 1. After settling and stratification, the upper layer of clear reaction liquid is controlled by the side valve of the catalyst settling separator 1 and sent to the tert-butanol recovery process through the clear reaction liquid recovery tank 100.
[0041] Then, demineralized water is added to a certain level for washing. The sedimentation and separation agitator 12 is started. After the catalyst slurry at the bottom is completely mixed with the demineralized water, the sedimentation and separation agitator 12 is stopped, and the mixture is allowed to settle and separate into layers again. The upper washing liquid is sent to the tert-butanol recovery process through the reaction clear liquid recovery tank 100 in the same way. The purpose of washing is to remove the small amount of ammonia and tert-butanol contained in the settled catalyst slurry.
[0042] (2) Catalyst separation: After the catalyst slurry at the bottom of the catalyst sedimentation separation tank 1 is washed with cyclohexanone oxime, ammonia and tert-butanol, demineralized water is added again to a certain level. The sedimentation separation stirrer 12 is started. After the catalyst slurry at the bottom is completely mixed with water, the angle valve 2 is opened and the sedimentation separation transfer pump 3 is started to send the catalyst aqueous solution to the catalyst separator 5. At this time, a certain amount of toluene has been added to the mixer 4 in advance. When the catalyst aqueous solution and toluene are mixed in the mixer 4 and enter the catalyst separator 5, the large particles of undamaged new catalyst quickly settle to the bottom. The small particles of deactivated catalyst are mixed with water and suspended on the upper layer of the aqueous solution of undamaged new catalyst, forming a clear interface two. The interface two is observed through the lower sight glass 53. After the toluene is mixed and extracted with a small amount of cyclohexanone oxime, it separates with the aqueous solution containing deactivated catalyst to form interface one. The interface one is observed through the middle sight glass 52. A liquid surface of toluene oxime solution is formed above the interface one. The liquid surface is observed through the upper sight glass 51.
[0043] (3) Recycling undamaged new catalyst: The slurry containing undamaged new catalyst at the bottom is returned to the oxime reactor 400 through the observation sight glass 6 to continue participating in the reaction.
[0044] (4) Toluene recovery: After the material is discharged, continue to add demineralized water to the catalyst separator 5, and overflow the top layer of toluene oxime solution to the extraction tank 300 to extract the upstream oxime solution as an extractant. Observe the top sight glass. When all the top toluene oxime solution is pushed out, switch the process.
[0045] (5) Recycling deactivated catalyst: The aqueous solution of deactivated catalyst is returned to catalyst settling tank 1. It is returned to catalyst settling tank 1 through the outlet return pipeline of settling separation pump 3 and allowed to stand and separate. The upper layer of aqueous solution containing a small amount of toluene is sent to the wastewater process through extraction tower 200 to recover toluene. Then, the catalyst aqueous solution without toluene after settling separation is sent to the waste catalyst pressure filtration process through the outlet of settling separation pump 3.
[0046] In summary, this utility model has the following advantages:
[0047] (1) When the catalyst aqueous solution discharged from the catalyst settling and separation tank 1 is mixed with toluene in the mixer 4 before the catalyst separator 5, it enters the catalyst separator 5. Large particles of undamaged new catalyst quickly settle to the bottom, thereby effectively separating the fresh large particles of catalyst added later from the discharged waste catalyst, so as to recover the catalyst and reduce the waste of catalyst.
[0048] (2) This embodiment utilizes the principle of extraction and separation using toluene as an extractant in existing processes, and toluene can be recycled back to the extraction process.
[0049] (3) Compared with the existing ceramic membrane alcohol washing and water washing processes, this operation process is simple, the cleaning time is short, the efficiency is high, and it does not require a large number of personnel to operate, thus reducing labor costs.
[0050] (4) After eliminating the existing ceramic membrane filter components, there is no need for acid and alkali chemical cleaning, which reduces the consumption of acid, alkali and desalination water, saving consumption costs.
[0051] (5) Corrosive hazardous chemicals such as acids and alkalis have been eliminated, thus eliminating potential safety hazards such as personnel contact with them during operation.
[0052] In the description of this utility model, it should be understood 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0053] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.
[0054] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0055] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. 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.
[0056] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A system for separating a catalyst from a turbid solution in a caprolactam ammoxime reaction, characterized in that, The system includes a catalyst settling tank, an angle valve, a settling separation pump, a mixer, and a catalyst separator. The feed end at the top of the catalyst settling tank is used to receive the reaction turbid liquid. The discharge end at the bottom of the catalyst settling tank is connected to the feed end of the settling separation pump through the angle valve. The discharge end of the settling separation pump is connected to the feed end of the mixer. The discharge end of the mixer is connected to the feed end in the middle of the catalyst separator. The discharge end at the bottom of the catalyst separator is used to discharge the slurry containing the catalyst. The mixer is also equipped with a toluene inlet, and the catalyst separator is equipped with a lower sight glass.
2. The system for separating a catalyst from a turbid solution in the caprolactam ammoxime reaction according to claim 1, characterized in that, The catalyst settling and separation tank is equipped with a tank wall sight glass and a drain outlet at the same height as the tank wall sight glass.
3. The system for separating a catalyst from a turbid solution in a caprolactam ammoxime reaction according to claim 1, characterized in that, The catalyst settling and separation tank is equipped with a settling and separation agitator and a first demineralized water inlet at the top.
4. The system for separating a catalyst from a turbid solution in the caprolactam ammoxime reaction according to claim 1, characterized in that, It also includes a discharge sight glass and a rotary discharge valve. The upper and middle parts of the catalyst separator are respectively provided with an upper sight glass and a middle sight glass. The mixer is also provided with a second demineralized water inlet. The discharge end at the bottom of the catalyst separator is connected in sequence to the discharge sight glass and the rotary discharge valve. The discharge end of the rotary discharge valve is connected to the oxime reaction vessel and the inlet end of the sedimentation separation pump. The discharge end of the sedimentation separation pump is also connected to the return end at the top of the catalyst sedimentation separation tank. Control valves are provided between the discharge end of the rotary discharge valve and the oxime reactor, between the discharge end of the rotary discharge valve and the inlet end of the sedimentation separation pump, between the discharge end of the sedimentation separation pump and the inlet end of the mixer, and between the discharge end of the sedimentation separation pump and the return end at the top of the catalyst sedimentation separation tank.
5. The system for separating a catalyst from a turbid solution in a caprolactam ammoxime reaction according to claim 1, characterized in that, The catalyst separator has two symmetrically arranged feed ends, and an inverted L-shaped baffle is arranged inside the catalyst separator above the feed ends.
6. The system for separating a catalyst from a turbid solution in the caprolactam ammoxime reaction according to claim 5, characterized in that, The catalyst separator has a grid plate installed above the baffle plate inside.
7. A system for separating a catalyst from a turbid solution in a caprolactam ammoxime reaction according to any one of claims 1 to 6, characterized in that, The catalyst separator is also provided with an overflow port at the top, which is used to connect to the extraction tank.
8. A system for separating a catalyst from a turbid solution in a caprolactam ammoxime reaction according to any one of claims 1 to 6, characterized in that, The discharge end of the sedimentation separation conveying pump is also connected to a filter press pipe, and a control valve is also installed on the filter press pipe. The filter press pipe is used to connect the waste catalyst filter press process.