Treatment method of piperidone synthesis tail gas

Abstract

The invention provides a piperidone synthesis tail gas treatment method, which comprises: (1) carrying out first condensation on piperidone synthesis tail gas to obtain a first condensate and a first non-condensable gas; performing second condensation on the first non-condensable gas to obtain second condensate and second non-condensable gas; recovering the first condensate and the second condensate with acetone to obtain an acetone product; (2) the second non-condensable gas is subjected to acid pickling absorption, and an absorption rich solution and absorption tail gas are obtained; crystallizing the absorption rich solution to obtain an ammonium salt product; and (3) sequentially carrying out water washing, third condensation and adsorption on the absorption tail gas to obtain purified gas. The method provided by the invention can realize recovery of acetone and resource utilization of ammonium sulfate by-products, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tail gas treatment, in particular to a treatment method of piperidone synthesis tail gas. BACKGROUND

[0002] Piperidone is a compound containing a piperidine ring, which is commonly used as an important intermediate in drug synthesis. This class of compounds has various applications, such as drug synthesis in the pharmaceutical industry, pesticide synthesis, and catalysts or reagents in other organic synthesis reactions.

[0003] Currently, the synthesis of piperidone can be achieved by various methods, mainly including oxidation reaction or dehydrogenation reaction using piperidine as raw material, and hydrolysis reaction using 3-aminopiperidine as raw material.

[0004] The synthesis method using piperidine as raw material involves using oxidizing agents (such as nitric acid, silver nitrate, etc.) to oxidize piperidine, or using dehydrogenation agents (such as sodium metal, copper metal, etc.) to dehydrogenate piperidine, thereby preparing 3-piperidone. This method utilizes the chemical properties of piperidine, and by controlling the reaction conditions, the synthesis of piperidone is achieved.

[0005] The synthesis method using 3-aminopiperidine as raw material is to convert 3-aminopiperidine into the corresponding diazonium salt, and then obtain 3-piperidone through hydrolysis reaction. This method has high yield and relatively simple operation process, and is suitable for industrial production and laboratory research.

[0006] In addition, the synthesis of 1-Cbz-4-piperidone can be prepared by condensation reaction of piperidone and the corresponding benzyloxy acid chloride under alkaline conditions. This method has the characteristics of high reaction efficiency and simple post-treatment, and is an effective way to prepare 1-Cbz-4-piperidone.

[0007] However, piperidone will produce tail gas containing acetone and ammonia gas during synthesis, which is difficult to handle, and there is an urgent need for a method to handle piperidone synthesis tail gas. SUMMARY

[0008] To solve the above technical problems, the present application provides a treatment method of piperidone synthesis tail gas, which can avoid deep cooling, greatly reduce the amount of absorption liquid used for absorption, and realize the recovery of acetone and the resource utilization of ammonium sulfate byproduct.

[0009] To achieve this purpose, the present application adopts the following technical solutions: In a first aspect, the present application provides a treatment method of piperidone synthesis tail gas, which comprises the following steps: (1) The piperidone synthesis tail gas is condensed for the first time to obtain a first condensed liquid and a first non-condensed gas; the first non-condensed gas is condensed for the second time to obtain a second condensed liquid and a second non-condensed gas; and the first condensed liquid and the second condensed liquid are recovered by acetone to obtain an acetone product; (2) The second non-condensed gas is absorbed by acid washing to obtain an absorption rich liquid and an absorption tail gas; and the absorption rich liquid is crystallized to obtain an ammonium salt product; (3) The absorption tail gas is sequentially washed by water, condensed for the third time and adsorbed to obtain a purified gas.

[0010] The treatment method of the piperidone synthesis tail gas provided by the application strictly sequentially carries out the processes of twice condensing, acid washing and absorbing, washing by water, condensing for the third time and adsorbing, can greatly reduce the amount of absorption liquid used without using deep cooling, and simultaneously realizes the recovery of acetone and the resource utilization of the ammonium sulfate byproduct.

[0011] Specifically, the process of the first condensing can realize the condensing of a large amount of acetone and a small amount of piperidone into the first condensed liquid, and the first non-condensed gas still contains a small amount of acetone and is mainly composed of ammonia and nitrogen; the first non-condensed gas is condensed for the second time, the acetone in the first non-condensed gas is condensed for the second time, the recovery of acetone is realized, and a high-purity acetone product can be obtained after the recovery of acetone.

[0012] At this time, the second non-condensed gas contains a small amount of ammonia, the ammonia in the absorption tower is absorbed to obtain an ammonium salt product, and the absorption tail gas is washed by water and condensed for the third time to obtain a purified gas.

[0013] In summary, the above-mentioned process not only realizes the recovery of acetone, the conversion of ammonia to ammonium salt resources, but also realizes the purification of the piperidone synthesis tail gas, and has a wide application prospect.

[0014] Preferably, the composition of the piperidone synthesis tail gas in step (1) includes water, nitrogen, ammonia, acetone, piperidone and methanol.

[0015] Preferably, the mass fraction of ammonia in the piperidone synthesis tail gas is 0.1-5wt%, for example, it can be 0.1wt%, 0.7wt%, 1.2wt%, 1.8wt%, 2.3wt%, 2.9wt%, 3.4wt%, 4wt%, 4.5wt% or 5wt% and the like.

[0016] Preferably, the mass fraction of water in the piperidone synthesis tail gas is 0.1-8wt%, for example, it can be 0.1wt%, 1wt%, 1.9wt%, 2.8wt%, 3.7wt%, 4.5wt%, 5.4wt%, 6.3wt%, 7.2wt% or 8wt% and the like.

[0017] Preferably, the mass fraction of acetone in the piperidone synthesis tail gas is 10-30wt%, for example, it can be 10wt%, 13wt%, 15wt%, 17wt%, 19wt%, 22wt%, 24wt%, 26wt%, 28wt% or 30wt%, etc.

[0018] Preferably, the mass fraction of methanol in the piperidone synthesis tail gas is 0.1-1wt%, for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1wt%, etc.

[0019] Preferably, the mass fraction of nitrogen in the piperidone synthesis tail gas is 75-90wt%, for example, it can be 75wt%, 77wt%, 79wt%, 80wt%, 82wt%, 84wt%, 85wt%, 87wt%, 89wt% or 90wt%, etc.

[0020] Preferably, the piperidone synthesis tail gas also contains piperidone.

[0021] Preferably, the content of piperidone in the piperidone synthesis tail gas is 0.05-2wt%, for example, it can be 0.05wt%, 0.27wt%, 0.49wt%, 0.7wt%, 0.92wt%, 1.14wt%, 1.35wt%, 1.57wt%, 1.79wt% or 2wt%, etc.

[0022] Preferably, the temperature of the first condensation is 2-10℃, for example, it can be 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃ or 10℃, etc.

[0023] The present application preferably controls the temperature of the first condensation within the above range, which can improve the recovery rate of acetone while reducing the content of acetone in the purified gas.

[0024] Preferably, the temperature of the second condensation is -10--35℃, for example, it can be -10℃, -12℃, -15℃, -18℃, -20℃, -22℃, -23℃, -25℃, -28℃, -30℃, -32℃ or -35℃, etc.

[0025] The present application preferably controls the temperature of the second condensation within the above range, which can improve the recovery rate of acetone while reducing the content of acetone in the purified gas, and reducing the large energy consumption problem caused by deep cooling.

[0026] The present application needs to control the temperature of the first condensation to be higher than the temperature of the second condensation, so as to condense a large amount of acetone first, and further condense acetone in the subsequent second condensation process. If the temperature of the first condensation is lower than the temperature of the second condensation, the second condensation process has no special condensation effect in nature, resulting in a decrease in the recovery rate of acetone and an increase in the content of ammonia in the purified gas.

[0027] Preferably, the composition of the first condensate includes 99.2-99.9wt% acetone, 0.2-0.5wt% ammonia, 0.01-0.03wt% nitrogen, and piperidone.

[0028] 99.2-99.9wt% acetone, for example, can be 99.2wt%, 99.3wt%, 99.4wt%, 99.5wt%, 99.6wt%, 99.7wt%, 99.8wt%, or 99.9wt%, etc.

[0029] 0.2-0.5wt% ammonia, for example, can be 0.2wt%, 0.24wt%, 0.27wt%, 0.3wt%, 0.34wt%, 0.37wt%, 0.4wt%, 0.44wt%, 0.47wt%, or 0.5wt%, etc.

[0030] 0.01-0.03wt% nitrogen, for example, can be 0.01wt%, 0.013wt%, 0.015wt%, 0.017wt%, 0.019wt%, 0.022wt%, 0.024wt%, 0.026wt%, 0.028wt%, or 0.03wt%, etc.

[0031] Preferably, the composition of the first non-condensable gas includes 3-5.5wt% acetone, 0.5-2wt% ammonia, and 92.5-96.5wt% nitrogen.

[0032] 3-5.5wt% acetone, for example, can be 3wt%, 3.2wt%, 3.5wt%, 3.6wt%, 4.0wt%, 4.2wt%, 4.5wt%, 4.5wt%, 5.0wt%, or 5.5wt%, etc.

[0033] 0.5-2wt% ammonia, for example, can be 0.5wt%, 0.67wt%, 0.84wt%, 1wt%, 1.17wt%, 1.34wt%, 1.5wt%, 1.67wt%, 1.84wt%, or 2wt%, etc.

[0034] 92.5~96.5wt% nitrogen, for example, can be 92.5wt%, 93.5wt%, 93.9wt%, 94.5wt%, 94.8wt%, 94.9wt%, 95.0wt%, 95.2wt%, 95.5wt%, or 96.5wt%, etc.

[0035] Preferably, the composition in the second condensate includes 99.3~99.9wt% acetone, 0.1~0.4wt% ammonia, and 0.01~0.03wt% nitrogen.

[0036] wherein 99.3~99.9wt% acetone, for example, can be 99.3wt%, 99.37wt%, 99.44wt%, 99.5wt%, 99.57wt%, 99.64wt%, 99.7wt%, 99.77wt%, 99.84wt%, or 99.9wt%, etc.

[0037] 0.1~0.4wt% ammonia, for example, can be 0.1wt%, 0.14wt%, 0.17wt%, 0.2wt%, 0.24wt%, 0.27wt%, 0.3wt%, 0.34wt%, 0.37wt%, or 0.4wt%, etc.

[0038] 0.01~0.03wt% nitrogen, for example, can be 0.01wt%, 0.013wt%, 0.015wt%, 0.017wt%, 0.019wt%, 0.022wt%, 0.024wt%, 0.026wt%, 0.028wt%, or 0.03wt%, etc.

[0039] Preferably, the composition in the second non-condensable gas includes 95~98wt% nitrogen, 1~3wt% ammonia, and 1~2wt% acetone.

[0040] wherein 95~98wt% nitrogen, for example, can be 95wt%, 95.5wt%, 95.9wt%, 96.5wt%, 96.9wt%, 97.1wt%, 97.5wt%, 97.6wt%, 97.9wt%, or 98wt%, etc.

[0041] 1~3wt% ammonia, for example, can be 1wt%, 1.3wt%, 1.5wt%, 1.7wt%, 1.9wt%, 2.2wt%, 2.4wt%, 2.6wt%, 2.8wt%, or 3wt%, etc.

[0042] 1~2wt% acetone, for example, can be 1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, or 2wt%, etc.

[0043] Preferably, the step of recovering acetone comprises condensation, absorption, adsorption and desorption.

[0044] Preferably, the purity of the acetone product is 50-95wt%, for example, it can be 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt%, etc.

[0045] Preferably, the recovery rate of the acetone is 70-99wt%, for example, it can be 70wt%, 74wt%, 77wt%, 80wt%, 83wt%, 87wt%, 90wt%, 93wt%, 96wt% or 99wt%, etc.

[0046] Preferably, the acid of the acid pickling comprises sulfuric acid.

[0047] Preferably, the concentration of the sulfuric acid is 5-30wt%, for example, it can be 5wt%, 8wt%, 11wt%, 14wt%, 17wt%, 19wt%, 22wt%, 25wt%, 28wt% or 30wt%, etc.

[0048] Preferably, the acid pickling absorption comprises: the non-condensable gas enters from the bottom of the first absorption tower, the acid is sprayed and washed from the top, the absorption tail gas is obtained from the top, and the absorption rich liquid is obtained from the bottom.

[0049] Preferably, the liquid-gas ratio of the acid to the non-condensable gas is (0.06-0.1):1, for example, it can be 0.06:1, 0.07:1, 0.07:1, 0.08:1, 0.09:1 or 0.1:1, etc.

[0050] The present application preferably controls the liquid-gas ratio of the acid to the non-condensable gas within the above range, which not only improves the recovery rate of ammonia gas, but also easily leads to insufficient adsorption of acetone during subsequent tail gas treatment when the acid is excessive, thereby causing the content of acetone in the purified gas to be relatively high.

[0051] Preferably, the temperature of the acid pickling absorption is 10-40℃, for example, it can be 10℃, 14℃, 17℃, 20℃, 24℃, 27℃, 30℃, 34℃, 37℃ or 40℃, etc.

[0052] Preferably, the pressure of the acid pickling absorption is 0.1-0.5MPa, for example, it can be 0.1MPa, 0.15MPa, 0.19MPa, 0.24MPa, 0.28MPa, 0.33MPa, 0.37MPa, 0.42MPa, 0.46MPa or 0.5MPa, etc.

[0053] Preferably, the upper part of the first absorption tower is provided with a tray, and the lower part is provided with a filler.

[0054] The upper part of the first absorption tower is provided with a tray and the lower part is provided with a filler, so that the absorption effect is relatively good and the amount of absorption liquid is relatively low, and the application prospect is broad.

[0055] It is worth mentioning that, since the gas phase after vacuum desorption is recycled to the first condensation or the second condensation of step (1), the steps are interrelated, and the change of the parameters of the subsequent steps will also affect the yield of acetone and the recovery rate of ammonia.

[0056] Preferably, the temperature of the crystallization is 30-50℃, for example, it can be 30℃, 33℃, 35℃, 37℃, 39℃, 42℃, 44℃, 46℃, 48℃ or 50℃, etc.

[0057] Preferably, the cooling rate of the crystallization is 20-50℃ / h, for example, it can be 20℃ / h, 24℃ / h, 27℃ / h, 30℃ / h, 34℃ / h, 37℃ / h, 40℃ / h, 44℃ / h, 47℃ / h or 50℃ / h, etc.

[0058] Preferably, the ammonium salt product is ammonium sulfate.

[0059] Preferably, the purity of the ammonium salt product is 90-99wt%, for example, it can be 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt% or 99wt%, etc.

[0060] Preferably, the water washing in step (3) includes: the absorption tail gas enters the second absorption tower from the bottom, and water is sprayed from the top for washing, so that the water washing tail gas is obtained at the top and the water washing liquid phase is obtained at the bottom.

[0061] Preferably, the water washing liquid phase goes to a sewage treatment system.

[0062] Preferably, the water includes desalinated water.

[0063] Preferably, the temperature of the third condensation is 1-10℃, for example, it can be 1℃, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃ or 10℃, etc.

[0064] Preferably, the adsorbent used in the adsorption is any one or a combination of at least two of activated carbon, resin, silica gel or molecular sieve, and a typical but non-limiting combination is a combination of activated carbon and resin, a combination of activated carbon and silica gel, a combination of silica gel and resin, and a combination of molecular sieve and resin.

[0065] Preferably, the temperature of the adsorption is -10~50℃, for example, it can be -10℃, -5℃, 0℃, 1℃, 2℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃ or 50℃, etc.

[0066] Preferably, the pressure of the adsorption is 90~200kPa, for example, it can be 90kPa, 100kPa, 115kPa, 120kPa, 130kPa, 150kPa, 160kPa, 175kPa, 185kPa or 200kPa, etc.

[0067] Preferably, the adsorption is followed by desorption.

[0068] Preferably, the desorption is vacuum desorption.

[0069] Preferably, the vacuum degree of the vacuum desorption is 0.1~20kPa, for example, it can be 0.1kPa, 2.4kPa, 4.6kPa, 6.8kPa, 9kPa, 11.2kPa, 13.4kPa, 15.6kPa, 17.8kPa or 20kPa, etc.

[0070] Preferably, the gas phase after the vacuum desorption is circulated to the first condensation or the second condensation of step (1).

[0071] As a preferred technical solution of the present application, the treatment method comprises the following steps: (1) piperidone synthesis tail gas (ammonia 0.1~5wt%, water 0.1~8wt%, acetone 10~30wt%, methanol 0.1~1wt%, nitrogen 75~90wt%, piperidone 0.05~2wt%) is condensed at 2~10℃ to obtain a first condensate (99.2~99.9wt% acetone, 0.2~0.5wt% ammonia, 0.01~0.03wt% nitrogen and trace piperidone) and a first non-condensable gas (3~5.5wt% acetone, 0.5~2wt% ammonia and 92.5~98.5wt% nitrogen); the first non-condensable gas is condensed at -10~-35℃ to obtain a second condensate (99.3~99.9wt% acetone, 0.1~0.4wt% ammonia and 0.01~0.03wt% nitrogen) and a second non-condensable gas (95~98wt% nitrogen, 1~3wt% ammonia and 1~2wt% acetone); the first condensate and the second condensate are subjected to acetone recovery to obtain an acetone product with a purity of 50~95wt%; the step of acetone recovery comprises condensation, absorption, adsorption and desorption; (2) the second non-condensed gas enters from the bottom of the first absorption tower, 5-30wt% sulfuric acid is sprayed from the top for washing, the liquid-gas ratio of sulfuric acid and non-condensed gas is (0.06-0.1):1, the temperature of acid washing absorption is 10-40℃, the pressure is 0.1-0.5MPa, the absorption tail gas is obtained at the top of the tower, and the absorption rich liquid is obtained at the bottom of the tower; the absorption rich liquid is crystallized at a cooling rate of 20-50℃ / h and a temperature of 30-50℃ to obtain an ammonium salt product with a purity of 90-99wt%; (3) the absorption tail gas enters the second absorption tower from the bottom, water is sprayed from the top for washing, the water washing tail gas is obtained at the top of the tower, and the water washing liquid phase is obtained at the bottom of the tower; the water washing liquid phase goes to a sewage treatment system, and the water washing tail gas is condensed at 1-10℃ and adsorbed at-10-50℃ and 90-200kPa to obtain a purified gas; the saturated adsorption is followed by vacuum desorption at a vacuum degree of 0.1-20kPa, and the gas phase after vacuum desorption is recycled to the first condensation or the second condensation of step (1).

[0072] Compared with the prior art, the present application has at least the following beneficial effects: (1) The treatment method of piperidone synthesis tail gas provided by the present application can realize the removal of piperidone, ammonia gas and acetone in the piperidone synthesis tail gas through the process of two condensations, acid washing absorption, water washing, third condensation and adsorption in sequence, so that a purified gas is obtained, and the acetone can be recovered, preferably, the recovery rate of acetone is above 95%, the ammonia gas can be recycled and reused in the form of ammonium sulfate, the recovery rate of ammonia is above 95%, the purity of ammonium sulfate is above 98.2wt%, and the application prospect is wide; (2) The treatment method of piperidone synthesis tail gas provided by the present application needs to be strictly carried out according to the steps of two condensations, acid washing absorption, water washing, third condensation and adsorption, and the process flow can avoid the need for a large amount of cold energy required by deep cooling and the harsh requirements for equipment; (3) Compared with the simple use of adsorption, the treatment method of piperidone synthesis tail gas provided by the present application can greatly reduce the amount of adsorbent, and the tail gas treatment effect is better, the content of acetone in the purified gas is within 34ppm, the content of ammonia gas is within 13ppm, and the content of piperidone is within 5.1ppm. BRIEF DESCRIPTION OF DRAWINGS

[0073] Figure 1 is a device schematic diagram of the treatment method of piperidone synthesis tail gas provided by the present application.

[0074] In the figure: 1, first condensation device; 2, second condensation device; 3, acid washing absorption tower; 4, water washing device; 5, third condensation device; 6, adsorption device; 7, acetone recovery unit; 8, crystallization device. DETAILED DESCRIPTION

[0075] For the purpose of understanding the present application, the present application is illustrated with the following examples. It should be apparent to those skilled in the art that the examples are merely illustrative of the present application and should not be viewed as limiting on the present application.

[0076] It should be noted that, in the description of the present application, the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship shown in the drawings, and are merely for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting on the present application. In addition, the terms "first", "second", and the like are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features defined with "first", "second", and the like can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0077] It should be noted that, in the description of the present application, unless otherwise specified and limited, the terms "provided", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0078] It should be understood by those skilled in the art that the present application necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing the complete process, but the above content does not belong to the main point of the present application, and those skilled in the art can add layout according to the process flow and equipment structure selection, and the present application does not make special requirements and specific limitations on this.

[0079] As a specific embodiment of the present application, a piperidone synthesis tail gas treatment device is provided, which is shown in Figure 1 The treatment device comprises a first condensing device, a second condensing device, an acetone recovery unit, an acid washing absorption tower, a crystallizing device, a water washing device, a third condensing device and an adsorbing device connected in sequence.

[0080] The first condensing device comprises a first condensed liquid outlet and a first non-condensed gas outlet; the second condensing device comprises a second condensed liquid outlet and a second non-condensed gas outlet; the first non-condensed gas outlet is connected with the second condensing device; the second condensed liquid outlet and the first condensed liquid outlet are connected with the acetone recovery unit; the second non-condensed gas outlet is connected with the pickling absorption tower, and the pickling absorption tower is provided with an absorption tail gas outlet at the top and an absorption rich liquid outlet at the bottom.

[0081] The absorption rich liquid outlet is connected with the crystallization device, and the absorption tail gas outlet is connected with the water washing device. The gas phase outlet of the water washing device, the third condensing device and the adsorption device are sequentially connected.

[0082] Figure 1 In the figure, A represents piperidone synthesis tail gas, B represents acetone product; C represents ammonium sulfate product; and D represents purified gas.

[0083] Embodiment 1 The embodiment provides a treatment method of piperidone synthesis tail gas, and the treatment method comprises the following steps: (1) piperidone synthesis tail gas (200 Nm 3 / h, 2.5wt% ammonia, 4wt% water, 11.9wt% acetone, 0.5wt% methanol, 81.05wt% nitrogen and 0.05wt% piperidone) is subjected to first condensation at 5°C to obtain first condensed liquid (99.7wt% acetone, 0.2wt% ammonia, 0.02wt% nitrogen and a small amount of piperidone) and first non-condensed gas (4.5wt% acetone, 2wt% ammonia and 93.5wt% nitrogen); the first non-condensed gas is subjected to second condensation at -10°C to obtain second condensed liquid (99.69wt% acetone, 0.3wt% ammonia and 0.01wt% nitrogen) and second non-condensed gas (92wt% nitrogen, 3wt% ammonia and 1.5wt% acetone); the first condensed liquid and the second condensed liquid are subjected to acetone recovery to obtain acetone product with a purity of 95wt%; the step of acetone recovery comprises condensation, absorption, adsorption and desorption; (2) the second non-condensed gas enters from the bottom of the first absorption tower, and 25wt% sulfuric acid is sprayed from the top for washing, the liquid-gas ratio of sulfuric acid and non-condensed gas is 0.08:1, the temperature of pickling absorption is 30°C, the pressure is 0.4MPa, absorption tail gas is obtained at the top, and absorption rich liquid is obtained at the bottom; the absorption rich liquid is subjected to crystallization at a cooling rate of 30°C / h at 40°C to obtain ammonium salt product; (3) the absorption tail gas enters the second absorption tower from the bottom, water is sprayed from the top for washing, water washing tail gas is obtained at the top, and water washing liquid phase is obtained at the bottom; the water washing liquid phase goes to a sewage treatment system, and the water washing tail gas is subjected to third condensation at 8°C and adsorption at 0°C and 100kPa to obtain purified gas; The adsorption saturation is followed by vacuum desorption at a vacuum degree of 15 kPa, and the gas phase after the vacuum desorption is circulated to the first condensation or the second condensation of step (1).

[0084] Example 2 The present example provides a treatment method for piperidone synthesis tail gas, which comprises the following steps: (1) The piperidone synthesis tail gas (ammonia 0.1 wt%, water 5 wt%, acetone 28 wt%, methanol 0.9 wt%, nitrogen 65 wt%, and piperidone 1 wt%) is subjected to first condensation at 5°C to obtain a first condensate (99.7 wt% acetone, 0.2 wt% ammonia, 0.03 wt% nitrogen, and trace amount of piperidone) and a first non-condensable gas (3 wt% acetone, 1.5 wt% ammonia, and 95.5 wt% nitrogen); the first non-condensable gas is subjected to second condensation at -35°C to obtain a second condensate (99.8 wt% acetone, 0.1 wt% ammonia, and 0.01 wt% nitrogen) and a second non-condensable gas (97.5 wt% nitrogen, 1 wt% ammonia, and 1.5 wt% acetone); the first condensate and the second condensate are subjected to acetone recovery to obtain an acetone product with a purity of 95 wt%; the step of acetone recovery comprises condensation, absorption, adsorption, and desorption; (2) The second non-condensable gas enters from the bottom of a first absorption tower, and 30 wt% sulfuric acid is sprayed from the top for washing, with a liquid-gas ratio of sulfuric acid to non-condensable gas being 0.06:1, a temperature of acid washing absorption being 10°C, and a pressure being 0.1 MPa; an absorption tail gas is obtained at the top, and an absorption rich liquid is obtained at the bottom; the absorption rich liquid is subjected to crystallization at 30°C with a cooling rate of 20°C / h to obtain an ammonium salt product; (3) The absorption tail gas enters a second absorption tower from the bottom, and water is sprayed from the top for washing; a water washing tail gas is obtained at the top, and a water washing liquid phase is obtained at the bottom; the water washing liquid phase goes to a sewage treatment system, and the water washing tail gas is subjected to third condensation at 10°C and adsorption at -10°C and 90 kPa to obtain a purified gas; The adsorption saturation is followed by vacuum desorption at a vacuum degree of 20 kPa, and the gas phase after the vacuum desorption is circulated to the first condensation or the second condensation of step (1).

[0085] Example 3 The present example provides a treatment method for piperidone synthesis tail gas, which comprises the following steps: (1) The piperidone synthesis tail gas (ammonia 5wt%, water 0.1wt%, acetone 10wt%, methanol 1wt%, nitrogen 81.9wt%, piperidone 2wt%) is condensed at 10℃ to obtain a first condensate (99.2wt% acetone, 0.5wt% ammonia, 0.03wt% nitrogen and trace piperidone) and a first non-condensable gas (5wt% acetone, 2wt% ammonia and 93wt% nitrogen); the first non-condensable gas is condensed at -10℃ to obtain a second condensate (99.3wt% acetone, 0.4wt% ammonia and 0.01wt% nitrogen) and a second non-condensable gas (97wt% nitrogen, 1wt% ammonia and 2wt% acetone); the first condensate and the second condensate are recovered by acetone to obtain an acetone product with a purity of 92wt%; the step of acetone recovery comprises condensation, absorption, adsorption and desorption; (2) The second non-condensable gas enters from the bottom of a first absorption tower, and 5wt% sulfuric acid is sprayed from the top for washing, with a liquid-gas ratio of sulfuric acid to non-condensable gas being 0.06:1, a temperature of acid washing absorption being 40℃, a pressure being 0.5MPa, an absorption tail gas being obtained at the top of the tower, and an absorption rich liquid being obtained at the bottom of the tower; the absorption rich liquid is crystallized at 50℃ with a cooling rate of 50℃ / h to obtain an ammonium salt product; (3) The absorption tail gas enters a second absorption tower from the bottom, and water is sprayed from the top for washing, with a water washing tail gas being obtained at the top of the tower, and a water washing liquid phase being obtained at the bottom of the tower; the water washing liquid phase goes to a sewage treatment system, and the water washing tail gas is condensed at 1℃ and adsorbed at 50℃ and 200kPa to obtain a purified gas; The adsorption is saturated, and vacuum desorption is performed at a vacuum degree of 0.1kPa, and the gas phase after vacuum desorption is recycled to the first condensation or the second condensation of step (1).

[0086] Example 4 The present example provides a treatment method for piperidone synthesis tail gas, which is the same as example 1 except that the temperature of the first condensation is 15℃, and details are not repeated here.

[0087] Example 5 The present example provides a treatment method for piperidone synthesis tail gas, which is the same as example 1 except that the temperature of the first condensation is -5℃, and details are not repeated here.

[0088] Example 6 The present example provides a treatment method for piperidone synthesis tail gas, which is the same as example 1 except that the temperature of the second condensation is -5℃, and details are not repeated here.

[0089] Example 7 The embodiment provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the temperature of the second condensation is -40 DEG C, which will not be repeated here.

[0090] Embodiment 8 The embodiment provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the liquid-gas ratio of sulfuric acid and non-condensable gas is 0.04:1, which will not be repeated here.

[0091] Embodiment 9 The embodiment provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the liquid-gas ratio of sulfuric acid and non-condensable gas is 0.04:1, which will not be repeated here.

[0092] Embodiment 10 The embodiment provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the temperature of the first condensation and the second condensation is exchanged, which will not be repeated here.

[0093] Comparative Example 1 The comparative example provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the first condensation is not performed, which will not be repeated here.

[0094] Comparative Example 2 The comparative example provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the second condensation is not performed, which will not be repeated here.

[0095] Comparative Example 3 The comparative example provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the third condensation is not performed, which will not be repeated here.

[0096] Comparative Example 4 The comparative example provides a treatment method of piperidone synthesis tail gas, which is the same as the treatment method in the embodiment 1 except that the water washing is not performed, which will not be repeated here.

[0097] Test method: according to the mass ratio of the recovered acetone to the acetone in the raw material tail gas, the acetone recovery rate is calculated; and the ammonium content in the ammonium sulfate and the ratio of the ammonia in the raw material tail gas are tested to calculate the ammonia recovery rate.

[0098] The test results of the above embodiment and comparative example are shown in Table 1.

[0099] Table 1

[0100] As can be seen from Table 1, the piperidone synthesis tail gas treatment method provided by the application can significantly improve the recovery rate of acetone, the content of piperidone in the purified gas is low, and the recovery of ammonia can be realized at the same time, and the application prospect is wide.

[0101] In Comparative Example 1, no first condensation is performed, not only the recovery rate of acetone decreases, but also the recovery rate of ammonia decreases accordingly, the content of acetone in the purified gas increases, and the purity of ammonium sulfate decreases; in Comparative Example 2, no second condensation is performed, the recovery rate of acetone decreases significantly, the content of acetone in the purified gas increases, and the purity of ammonium sulfate decreases; in Comparative Example 3, no third condensation is performed, which leads to a significant decrease in the recovery rate of acetone; in Comparative Example 4, no water washing is performed, which leads to the presence of a large amount of impurity gas in the gas phase recycled after vacuum desorption, thereby leading to a decrease in the purity of ammonium sulfate and a decrease in the recovery rate of acetone. It is shown that, by comprehensively adopting the combination of each step, the application can significantly improve the recovery rate of acetone and the recovery rate of ammonia in the piperidone synthesis tail gas, and the content of acetone and piperidone in the purified gas is low, and the application prospect is wide.

[0102] The economic efficiency and energy consumption are calculated by taking Example 1 as an example: In Example 1, 312 tons of acetone are recovered per year (calculated according to 8000 hours of annual operation), and the value is about 1.7 million yuan (calculated at 5500 yuan per ton at present); 88 tons of sulfuric acid are consumed per year (calculated according to 8000 hours of annual operation), and the investment is about 52,000 yuan (calculated at the current market price of 98% sulfuric acid of 600 yuan / ton).

[0103] If ammonia gas is recovered, about 120 tons of ammonium sulfate are produced per year, and the value is about 138,000 yuan (calculated at 1150 yuan / ton).

[0104] The power consumption of the device is 44.55 kW, the annual power consumption is 257,400 kW·h, the water consumption of the device is 200 kg / h, and the annual water consumption is 1600 t (calculated according to 8000 hours of annual operation).

[0105] The economic benefit is: 1700000-52000+138000-25.74x10000x0.9 (average electricity fee)-1600x3.38=1548932 yuan=154.89 million yuan.

[0106] It is shown that the piperidone synthesis tail gas treatment method provided by the application not only realizes the treatment of tail gas and saves the tail gas treatment fee, but also has high economic value.

[0107] The detailed features of the present application are illustrated by the above-mentioned embodiments, but the present application is not limited to the above-mentioned detailed features, i.e. it does not mean that the present application must rely on the above-mentioned detailed features to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the selected technical features of the present application, addition of auxiliary technical features, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for treating a piperidone synthesis off-gas, characterized in that, The processing method comprises the following steps: (1) the piperidone synthesis tail gas is condensed for the first time to obtain a first condensed liquid and a first non-condensed gas; the first non-condensed gas is condensed for the second time to obtain a second condensed liquid and a second non-condensed gas; the first condensed liquid and the second condensed liquid are recovered by acetone to obtain an acetone product; (2) the second non-condensed gas is absorbed by acid washing to obtain an absorption rich liquid and an absorption tail gas; the absorption rich liquid is crystallized to obtain an ammonium salt product; (3) the absorption tail gas is sequentially washed by water, condensed for the third time and adsorbed to obtain a purified gas.

2. The treatment method according to claim 1, characterized in that, The piperidone synthesis tail gas in step (1) comprises water, nitrogen, ammonia, acetone, piperidone and methanol; Preferably, the mass fraction of ammonia in the piperidone synthesis tail gas is 0.1-5wt%; Preferably, the mass fraction of water in the piperidone synthesis tail gas is 0.1-8wt%; Preferably, the mass fraction of acetone in the piperidone synthesis tail gas is 10-30wt%; Preferably, the mass fraction of methanol in the piperidone synthesis tail gas is 0.1-1wt%; Preferably, the mass fraction of nitrogen in the piperidone synthesis tail gas is 75-90wt%; Preferably, the piperidone synthesis tail gas further comprises piperidone; Preferably, the content of piperidone in the piperidone synthesis tail gas is 0.05-2wt%.

3. The treatment method according to claim 1 or 2, characterized in that, The temperature of the first condensation is 2-10℃; Preferably, the temperature of the second condensation is-10--35℃; Preferably, the composition of the first condensed liquid comprises 99.2-99.9wt% acetone, 0.2-0.5wt% ammonia, 0.01-0.03wt% nitrogen and a small amount of piperidone; Preferably, the composition of the first non-condensed gas comprises 3-5.5wt% acetone, 0.5-2wt% ammonia and 92.5-96.5wt% nitrogen; Preferably, the composition of the second condensed liquid comprises 99.3-99.9wt% acetone, 0.1-0.4wt% ammonia and 0.01-0.03wt% nitrogen; Preferably, the composition of the second non-condensed gas comprises 95-98wt% nitrogen, 1-3wt% ammonia and 1-2wt% acetone.

4. The treatment method according to any one of claims 1 to 3, characterized in that, The step of recovering acetone comprises condensation, absorption, adsorption and desorption; Preferably, the purity of the acetone product is 50-95wt%; Preferably, the recovery rate of acetone is 70-99wt%.

5. The treatment method according to any one of claims 1 to 4, characterized in that, The acid of the acid washing comprises sulfuric acid; Preferably, the concentration of the sulfuric acid is 5-30wt%.

6. The treatment method according to any one of claims 1 to 5, characterized in that, The acid washing absorption comprises that the non-condensed gas enters from the bottom of a first absorption tower, the acid is sprayed and washed from the top, the absorption tail gas is obtained at the top and the absorption rich liquid is obtained at the bottom; Preferably, the liquid-gas ratio of the acid to the non-condensed gas is (0.06-0.1):1; Preferably, the temperature of the acid washing absorption is 10-40℃; Preferably, the pressure of the acid washing absorption is 0.1-0.5MPa; Preferably, the upper part of the first absorption tower is provided with a tower tray and the lower part is provided with a filler.

7. The treatment method according to any one of claims 1 to 6, characterized in that, The temperature of the crystallization is 30-50℃; Preferably, the cooling rate of the crystallization is 20-50℃ / h; Preferably, the ammonium salt product is ammonium sulfate; Preferably, the purity of the ammonium salt product is 90-99wt%.

8. The treatment method according to any one of claims 1 to 7, characterized in that, The water washing in step (3) comprises: absorbing the tail gas from the bottom of the column into the second absorption column, spraying water from the top of the column for washing, obtaining water washing tail gas from the top of the column, and obtaining water washing liquid phase from the bottom of the column; Preferably, the water washing liquid phase goes to a sewage treatment system. Preferably, the water comprises desalinated water. Preferably, the temperature of the third condensation is 1-10℃.

9. The treatment method according to any one of claims 1 to 8, characterized in that, The adsorbent used in the adsorption is any one or a combination of at least two of activated carbon, resin, silica gel or molecular sieve; Preferably, the temperature of the adsorption is -10-50℃. Preferably, the pressure of the adsorption is 90-200kPa.

10. The treatment method according to any one of claims 1 to 9, characterized in that, After the adsorption saturation, desorption is performed. Preferably, the desorption uses vacuum desorption. Preferably, the vacuum degree of the vacuum desorption is 0.1-20kPa. Preferably, the gas phase after the vacuum desorption is recycled to the first condensation or the second condensation in step (1).

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