Process for producing ortho-aminophenol by taking n-butyl alcohol as solvent

Abstract

The invention provides a method for producing ortho-aminophenol by taking n-butyl alcohol as a solvent, which comprises the following steps: adding hydrogen into ortho-nitrophenol in an n-butyl alcohol-water solvent under the action of a catalyst, and carrying out reduction reaction to obtain ortho-aminophenol feed liquid; crystallizing the ortho-aminophenol feed liquid to obtain an ortho-aminophenol wet material and a mixed mother solution; separating the mother liquor to obtain recovered mother liquor containing n-butyl alcohol and a water phase; and using the recovered mother liquor containing n-butyl alcohol as a solvent for the reduction reaction. Compared with the conventional process taking methanol and ethanol as solvents, the method has the advantages that the process and time for recovering the mother liquor are shortened, and the production efficiency is improved; the recovery rate of ortho-aminophenol in the mother liquor is increased, meanwhile, solid waste difficult to treat generated in the mother liquor rectification process is reduced, and environmental pollution is reduced; the water-phase rectification is intermittent operation, and the mother liquor can be used mechanically, so that the amount of a rectification solvent is reduced compared with the solvent rectification of a conventional process.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of o-aminophenol, and in particular to a process for producing o-aminophenol by hydrogenation reduction using n-butanol as solvent. Background Art

[0002] At present, the production process of o-aminophenol generally uses methanol and ethanol as solvents to carry out hydrogenation reduction reaction, and then crystallizes and dries to obtain o-aminophenol products; the centrifuged mother liquor is distilled to recover the solvent so that the solvent can be used in production. The o-aminophenol production process using such solvents has the following disadvantages: the mother liquor distillation and solvent recovery process is long, and the distillation energy consumption is large; the o-aminophenol remaining in the mother liquor can basically not be recovered, the o-aminophenol yield is low, resulting in high production costs; due to the high distillation temperature, the o-aminophenol remaining in the mother liquor will be oxidized into high-boiling products such as tar at high temperature, forming harmful solid waste that is difficult to treat, which is difficult to treat and has high treatment costs, which is not conducive to saving resources and environmental protection.

[0003] The o-aminophenol production process currently adopted by the applicant is CN103739505A: using o-nitrophenol as raw material, using Pd / Al2O3 catalyst, 50-85% ethanol-water solution as solvent, continuous catalytic hydrogenation reaction is carried out in a fixed bed reactor, and the target product o-aminophenol is obtained after separation and purification.

[0004] Patent publication document CN114181098A mixes and dissolves 60% ethanol and o-nitrophenol through a pipeline mixer, sends the dissolved material to a hydrogenation device, adds a catalyst, heats, pressurizes and hydrogenates, and the hydrogenated liquid after the reaction passes through a catalyst continuous settler and a ceramic membrane filtration system to remove the catalyst, and the clear liquid is cooled, crystallized, and centrifuged to obtain wet o-aminophenol. The liquid ethanol mother liquor after centrifugation is collected in a mother liquor tank and regularly transferred to a distillation kettle for distillation and recovery of ethanol, which is then reused in the hydrogenation reduction process.

[0005] Patent publication document CN117304041A uses o-nitrophenol as a raw material, Pt / C or Pd / C as a catalyst, and an aqueous solution of methanol, ethanol or ethyl acetate as a solvent, and performs a continuous catalytic hydrogenation reaction through a Venturi reactor to produce an o-aminophenol product.

[0006] Patent publication CN111302955A reacts nitrophenol with hydrogen in the presence of an auxiliary agent and n-butanol solvent. This method also has the problem of a long process flow, and also requires the addition of an auxiliary agent, which increases the difficulty of removing harmful pollutants from the product. Summary of the invention

[0007] The technical problem to be solved by the present invention is that in the prior art, methanol or ethanol-water solution is used as the solvent for the hydrogenation reduction reaction of o-nitrophenol, which leads to a long process flow for recovering the solvent by distillation of the mother liquor and a low recovery rate of o-aminophenol.

[0008] In order to solve the above problems, the present invention provides a method for producing o-aminophenol using n-butanol as a solvent, the method comprising:

[0009] Reduction reaction: o-nitrophenol is reduced in n-butanol-water solvent by adding hydrogen gas under the action of a catalyst to obtain o-aminophenol liquid;

[0010] Crystallization: crystallizing the o-aminophenol liquid to obtain o-aminophenol wet material and mixed mother liquor;

[0011] Mixed mother liquor separation: separating the mother liquor to obtain a recovered mother liquor containing n-butanol and an aqueous phase;

[0012] Mother liquor recycling: the recovered mother liquor containing n-butanol is used as the solvent for the reduction reaction.

[0013] In the above scheme of the present invention, n-butanol-water solvent is used as the solvent for the hydrogenation reduction reaction of o-nitrophenol, and the solubility of o-aminophenol in n-butanol is higher than that in methanol and ethanol, which is more conducive to the hydrogenation reaction. The crystallization mother liquor is directly used in the hydrogenation reaction process after stratification and decolorization, which greatly reduces the time and process required for solvent recovery, improves production efficiency, and greatly reduces energy consumption; the solvent of uncrystallized o-ammonia is directly taken back to the hydrogenation reaction, reduces product loss, and improves the yield of o-ammonia; the generation of harmful and hazardous wastes such as tar generated by residual o-aminophenol in the mother liquor during the high-temperature distillation process is reduced, which is conducive to saving resources and protecting the environment, and has good economic and social benefits. At the same time, n-butanol-water solvent is milder than ethanol solvent, improves the safety of production equipment, and is more suitable for promotion and application in industrial production.

[0014] Preferably, in the reduction reaction, the ratio of the volume of the n-butanol-water solvent to the mass of o-nitrophenol is 3-5:1, and the mass fraction of n-butanol in the n-butanol-water solvent is 60%-85%.

[0015] Preferably, the mixed mother liquor separation method is: the mixed mother liquor is allowed to stand for 10 minutes to 30 minutes, and the mixed mother liquor is separated into layers to obtain a recovered mother liquor containing n-butanol and an aqueous phase.

[0016] Preferably, the content of n-butanol in the recovered mother liquor containing n-butanol is 70% to 85%.

[0017] Preferably, the method further comprises: drying the wet o-aminophenol material to obtain the o-aminophenol finished product.

[0018] Preferably, the aqueous phase obtained in the crystallization step is distilled to obtain water and n-butanol solution, and the n-butanol solution is used to replenish the solvent loss solution of the reduction reaction.

[0019] Preferably, the solvent in the reduction reaction consists of 50% to 90% of recovered mother liquor and 50% to 10% of n-butanol-water solvent.

[0020] Preferably, the solvent in the reduction reaction is 100% recycled mother liquor.

[0021] Preferably, in the mixed mother liquor separation step, the aqueous phase contains about 7% n-butanol and water, and each batch produces about 0.45m 3 , need to be temporarily stored in the liquid storage tank until the volume of the liquid storage tank is greater than 5m 3 When the product is distilled, it enters the distillation tower for distillation operation.

[0022] Preferably, the distillation process controls the top temperature of the distillation tower to 91±2° C., and the distilled water is collected and used as process water, and the recovered n-butanol has a mass fraction of about 80%.

[0023] The technical effects of the present invention are:

[0024] 1. The solubility of o-aminophenol in n-butanol of the present invention is higher than that in methanol and ethanol, which is more conducive to the hydrogenation reaction. The crystallization mother liquor of the present invention is directly applied to the hydrogenation reaction after stratification, which greatly reduces the time and process required for solvent recovery, improves production efficiency, and greatly reduces energy consumption; the uncrystallized o-ammonia is directly brought back to the hydrogenation reaction by the recycled solvent, which reduces product loss and improves the yield of o-ammonia; the present invention reduces the generation of harmful wastes such as tar generated by residual o-aminophenol in the mother liquor during the high-temperature distillation process, which is conducive to saving resources and protecting the environment, and has good economic and social benefits. At the same time, the n-butanol-water solvent is milder than the ethanol solvent, improves the safety of the production device, and is more suitable for promotion and application in industrial production. The present invention uses n-butanol as the hydrogenation reduction solvent, and the mother liquor obtained after the reduction liquid crystallization centrifugation can be directly stratified and decolorized without distillation to obtain a directly applicable n-butanol-water solvent, which greatly shortens the process and time required for solvent recovery in the mother liquor and improves production efficiency.

[0025] 2. The centrifugal mother liquor after the crystallization of the present invention contains water and n-butanol generated by hydrogenation reaction, the n-butanol-water solution is stratified by standing, the upper organic phase contains n-butanol, the lower aqueous phase contains a small amount of n-butanol, the upper n-butanol solution can be directly used as a solvent for hydrogenation reaction after decolorization, wherein the o-aminophenol containing part of the non-crystallized o-aminophenol is dissolved in the solvent and directly reused in the hydrogenation process, because it does not need to enter the rectification system, the o-aminophenol in the solvent is avoided from being oxidized and carbonized due to high-temperature rectification, thereby improving the yield of o-aminophenol, and reducing the material loss and energy consumption caused by the solvent rectification process. The lower aqueous phase (containing about 7% n-butanol) is concentratedly collected and then rectified to obtain 80% n-butanol, which is temporarily stored in a solvent storage tank to supplement the solvent loss.

[0026] 3. Different from CN111302955A, which synthesizes aminophenol and p-aminophenol, the present invention is used for o-aminophenol. No acidic auxiliary agent is required in the raw material of the present invention, and the solvent of the present invention only needs n-butanol-water solution. The solvent of the present invention is specifically n-butanol water solvent, and the target product o-aminophenol. The present invention discloses a process for producing o-aminophenol by catalytic hydrogenation using n-butanol-water solution as solvent, especially for the mother liquor re-use treatment process, and no similar process is mentioned in the relevant literature and patents. The solvent recovery of the present invention is simple, that is, the mother liquor is directly stratified and decolorized and reused, and it is not necessary to rectify the mother liquor, distillation and other complex and high energy consumption processes, and it is only necessary to collect the water phase after stratification and rectify it, because the mother liquor recovery rate is high, 10-11 batches of reactions are rectified once, and the conventional process generally 1-2 batches of reactions are rectified once, so that energy consumption is greatly reduced, and the solvent recovery time is greatly shortened. And for o-aminophenol, the solubility in n-butanol solvent is higher, which is more conducive to the catalytic hydrogenation reaction.

[0027] 3. The uncrystallized o-aminophenol in the mother liquor of the present invention is dissolved in the n-butanol solution and can be returned to the reduction production along with the solvent, thereby improving the yield of o-aminophenol and reducing the unit loss of the product; at the same time, the high-boiling organic solid waste generated during the high-temperature distillation process of the mother liquor is reduced, thereby reducing environmental pollution.

[0028] 4. Compared with the solvents such as methanol and ethanol used in conventional processes, the physical and chemical properties of n-butanol-water solvent are milder and more stable, further improving the safety of the production device. The present invention realizes the recycling of solvents, and there is no pollution emission and material loss in the entire production process, which is conducive to further reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a process flow chart for producing o-aminophenol using n-butanol as solvent. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. The implementation conditions adopted in the embodiments can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional implementation conditions in the industry.

[0031] The present invention provides a method for producing o-aminophenol by using n-butanol as solvent, characterized in that the method comprises:

[0032] Reduction reaction: o-nitrophenol is reduced in n-butanol-water solvent under the action of a catalyst by adding hydrogen to obtain o-aminophenol liquid; in the reduction reaction, the reaction temperature is 80°C to 140°C, and the reaction pressure is 1.0Mpa to 2.0Mpa; the intermittent hydrogenation reaction time is controlled to be 2h to 4h; in the hydrogenation reduction reaction, the ratio of the volume of n-butanol-water solvent to the mass of o-nitrophenol (V 溶剂 :M 邻硝 ) is 3 to 5:1, the mass fraction of n-butanol in the n-butanol-water solvent is 60% to 85%, the catalyst type is a palladium carbon catalyst or a platinum carbon catalyst, and the catalyst addition ratio is 1wt% to 5wt%. In one embodiment, in order to shorten the hydrogenation reaction time and improve the hydrogenation reaction efficiency, when o-nitrophenol and n-butanol-water solvent are prepared, they are preheated to 60°C to 80°C in advance.

[0033] Crystallization: crystallizing the o-aminophenol liquid to obtain o-aminophenol wet material and mixed mother liquor; preferably, before the crystallization step, the catalyst in the o-aminophenol liquid is filtered out, and the crystallization temperature is 10°C to -10°C. In one embodiment, in order to better control the crystal form and reduce the energy consumption of the crystallization process, the cooling crystallization process of the reducing liquid is carried out in a combination of circulating water and chilled brine, that is, first cooling the temperature to 20°C to 30°C with circulating water, and then cooling the temperature to 10°C to -10°C with chilled brine.

[0034] Wet material drying: the o-aminophenol wet material is dried to obtain the o-aminophenol finished product, the drying temperature is 70°C to 100°C, and the drying is carried out under a slight negative pressure.

[0035] Mixed mother liquor separation: the mother liquor is separated to obtain a recovered mother liquor containing n-butanol and an aqueous phase; the mixed mother liquor is separated to obtain a recovered mother liquor containing n-butanol and an aqueous phase, and the recovered mother liquor containing n-butanol is used as a solvent for the reduction reaction. Preferably, the recovered mother liquor containing n-butanol obtained by separation is decolorized and used as a solvent for the reduction reaction. The method for separating the mixed mother liquor is: the mixed mother liquor is allowed to stand for 10 min to 30 min, and the recovered mother liquor and an aqueous phase containing n-butanol are obtained after the mixed mother liquor is layered. The content of n-butanol in the recovered mother liquor is 75% to 85%, and the lower aqueous phase contains 7% to 10% n-butanol; the aqueous phase is discharged to a liquid storage tank for temporary storage, and the aqueous phase is distilled to obtain water and n-butanol solution, and the n-butanol solution is used as a solvent loss replenishment solution for the reduction reaction. Preferably, the aqueous phase produces about 0.45m per batch 3 , need to be temporarily stored in the liquid storage tank until the volume of the liquid storage tank is greater than 5m 3 When the distillation tower is used, the distillation tower is used for distillation. The top temperature of the distillation tower is controlled at 91±2℃ during the distillation process, and 80% to 85% of the mass fraction of n-butanol-water solution and process water are separated. The distilled water is collected and used as process water. Compared with the existing process, the operation time of the distillation unit and the total amount of distillation are reduced by more than 90%, and the energy consumption is greatly reduced.

[0036] Mother liquor recycling: The recovered mother liquor containing n-butanol is used as the solvent for the reduction reaction. In one embodiment, the solvent in the reduction reaction is composed of 50% to 90% of the recovered mother liquor and 50% to 10% of the n-butanol-water solvent. In one embodiment, the solvent in the reduction reaction is 100% of the recovered mother liquor.

[0037] The present invention is described below by means of specific examples.

[0038] Example 1

[0039] Using n-butanol-water solution as solvent, catalytic hydrogenation is used to produce o-aminophenol. The steps are as follows:

[0040] Reduction reaction: according to the ratio of material V 80％正丁醇-水 :M 邻硝基苯酚 =4:1, o-nitrophenol and 80% n-butanol-water solvent are added to a hydrogenation reactor, nitrogen is replaced, preheated, and 3wt% of palladium carbon catalyst is added; the hydrogenation reactor is heated, hydrogen is introduced, the reaction temperature is maintained at 120°C, the reaction pressure is maintained at 1.2Mpa, and a hydrogenation reduction reaction is started to obtain an o-aminophenol feed liquid;

[0041] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0042] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by air flow, with the drying temperature maintained at 80°C and slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.9% and a total yield of 86.5%.

[0043] Separation of mother liquor and mother liquor recycling: The mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers. The upper layer is an organic phase containing 80% of n-butanol in the recovered mother liquor, and the lower layer is an aqueous phase containing 7% of n-butanol. The aqueous phase is discharged to a liquid storage tank for temporary storage, and the recovered mother liquor is decolorized and then participates in the next hydrogenation reduction reaction.

[0044] Example 2

[0045] The recovered mother liquor and new n-butanol-water solvent in different proportions are mixed and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor: n-butanol-water solvent is 5:5, wherein the recovered mother liquor contains 80% n-butanol, and the n-butanol-water solvent is an aqueous solution with a mass fraction of n-butanol of 80%.

[0046] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of palladium carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0047] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0048] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by air flow, with the drying temperature maintained at 80°C and slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.7% and a total yield of 94.2%.

[0049] Separation of mother liquor and mother liquor recycling: The mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 80% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to a liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0050] Example 3

[0051] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 80% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of 80% n-butanol.

[0052] Reduction reaction: according to the ratio of material V溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of palladium carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0053] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0054] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by airflow, with the drying temperature maintained at 80°C and slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.5% and a total yield of 96.1%.

[0055] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 80% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0056] Example 4

[0057] The mother liquor and new n-butanol-water solvent in different proportions are mixed and used as hydrogenation solvent. The solvent is 100% recycled mother liquor, and the recycled mother liquor contains 80% n-butanol.

[0058] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of palladium carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0059] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0060] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by airflow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.3% and a total yield of 97.5%.

[0061] Separation of mother liquor and mother liquor recycling: The mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 80% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to a liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0062] Example 5

[0063] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 9:1. The recovered mother liquor contained 80% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of 80% n-butanol.

[0064] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of palladium carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0065] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0066] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by airflow, with the drying temperature maintained at 80°C and slight negative pressure, and finally an off-white crystalline powder sample was obtained with a purity of 99.3% and a total yield of 95.2%;

[0067] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 80% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0068] Example 6

[0069] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 80% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of n-butanol of 60%.

[0070] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚=4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of palladium carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0071] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0072] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by airflow, with the drying temperature maintained at 80°C and slight negative pressure, and finally an off-white crystalline powder sample was obtained with a purity of 99.7% and a total yield of 95.8%;

[0073] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 80% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0074] Example 7

[0075] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 85% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of 85% n-butanol.

[0076] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of palladium carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0077] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0078] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by airflow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.5% and a total yield of 95.7%.

[0079] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 85% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0080] Example 8

[0081] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 75% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of n-butanol of 80%.

[0082] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of platinum-carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0083] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0084] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by airflow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.6% and a total yield of 96.5%.

[0085] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 75% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0086] Example 9

[0087] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 75% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of n-butanol of 80%.

[0088] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚=3:1, o-nitrophenol and solvent are added into a hydrogenation reactor, nitrogen is replaced, preheated, and 3 wt% of platinum-carbon catalyst is added; the hydrogenation reactor is heated, hydrogen is introduced, the reaction temperature is maintained at 120° C., the reaction pressure is maintained at 1.2 MPa, and a hydrogenation reduction reaction is started to obtain an o-aminophenol feed liquid;

[0089] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0090] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by air flow, with the drying temperature maintained at 80°C and slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.1% and a total yield of 97.2%.

[0091] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 75% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0092] Example 10

[0093] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 75% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of n-butanol of 80%.

[0094] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =5:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of platinum-carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0095] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0096] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by air flow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.7% and a total yield of 95.1%.

[0097] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 75% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0098] Embodiment 11

[0099] The recovered mother liquor and new n-butanol-water solvent were mixed in different proportions and used as hydrogenation solvent, and the volume ratio of the recovered mother liquor to n-butanol-water solvent was 7:3. The recovered mother liquor contained 70% n-butanol, and the n-butanol-water solvent was an aqueous solution with a mass fraction of n-butanol of 80%.

[0100] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, adding o-nitrophenol and solvent into a hydrogenation reactor, replacing with nitrogen, preheating, adding 3wt% of platinum-carbon catalyst; heating the hydrogenation reactor, introducing hydrogen, maintaining the reaction temperature at 120°C and the reaction pressure at 1.2Mpa, starting a hydrogenation reduction reaction, and obtaining an o-aminophenol feed liquid;

[0101] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0102] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by air flow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.4% and a total yield of 95.6%.

[0103] Mother liquor separation and mother liquor recycling: the mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers, the upper organic phase contains about 70% n-butanol, and the lower aqueous phase contains about 7% n-butanol; the aqueous phase is discharged to the liquid storage tank for temporary storage, and the organic phase is decolorized and then participates in the next hydrogenation reduction reaction.

[0104] Comparative Example 1

[0105] The steps of producing o-aminophenol by catalytic hydrogenation using methanol as solvent are as follows:

[0106] Reduction reaction: According to the ratio of materials (V 溶剂 :M 邻硝基苯酚 ): 4:1, o-nitrophenol and 80% methanol-water solvent are added to a hydrogenation reactor, nitrogen is replaced, preheated, and 3wt% palladium carbon catalyst is added; the hydrogenation reactor is heated, hydrogen is introduced, the reaction temperature is maintained at 100° C., the reaction pressure is maintained at 1.0 MPa, and a hydrogenation reduction reaction is started to obtain an o-aminophenol feed liquid;

[0107] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0108] Wet material drying: The o-aminophenol wet material obtained by centrifugation is dried by air flow, and the drying temperature is maintained at 80°C and a slight negative pressure is used for drying, and finally a slightly reddish to grayish red crystalline powder o-aminophenol sample is obtained, with a purity of 99.3% and a total yield of 88.8%.

[0109] Comparative Example 2

[0110] Using ethanol as solvent, catalytic hydrogenation is used to produce o-aminophenol. The steps are as follows:

[0111] Reduction reaction: According to the ratio of materials (V 溶剂 :M 邻硝基苯酚 ): 4:1, o-nitrophenol and 80% ethanol-water solvent are added to a hydrogenation reactor, nitrogen is replaced, preheated, and 3wt% palladium-carbon catalyst is added; the hydrogenation reactor is heated, hydrogen is introduced, the reaction temperature is maintained at 100° C., and the reaction pressure is maintained at 1.0 MPa, and a hydrogenation reduction reaction is started to obtain an o-aminophenol feed liquid;

[0112] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0113] Wet material drying: The o-aminophenol wet material obtained by centrifugation is dried by air flow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an o-aminophenol sample as off-white to white crystalline powder with a purity of 99.5% and a total yield of 88.1%.

[0114] Comparative Example 3

[0115] The ethanol mother liquor in comparative example 2 was mixed with ethanol-water solvent and used as hydrogenation solvent, and the volume ratio of recovered ethanol mother liquor to ethanol-water solvent was 4:6. The recovered mother liquor contained about 60% ethanol, and the ethanol-water solvent was an aqueous solution with a mass fraction of 95% ethanol.

[0116] Reduction reaction: According to the ratio of materials (V 溶剂 :M 邻硝基苯酚 ): 4:1, o-nitrophenol and solvent are added to a hydrogenation reactor, nitrogen is replaced, preheated, and 3 wt% of palladium carbon catalyst is added; the hydrogenation reactor is heated, hydrogen is introduced, the reaction temperature is maintained at 100° C., the reaction pressure is maintained at 1.0 MPa, and a hydrogenation reduction reaction is started to obtain an o-aminophenol feed liquid;

[0117] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0118] Wet material drying: The o-aminophenol wet material obtained by centrifugation is dried by air flow, with the drying temperature maintained at 80°C and a slight negative pressure, to finally obtain an o-aminophenol sample as off-white to white crystalline powder with a purity of 99.4% and a total yield of 91.3%.

[0119] Comparative Example 4

[0120] Using n-butanol as solvent, catalytic hydrogenation is used to produce o-aminophenol. The steps are as follows:

[0121] Reduction reaction: according to the ratio of material V 溶剂 :M 邻硝基苯酚 =4:1, o-nitrophenol and 100% n-butanol solvent are added to a hydrogenation reactor, nitrogen is replaced, preheated, and 3wt% of palladium carbon catalyst is added; the hydrogenation reactor is heated, hydrogen is introduced, the reaction temperature is maintained at 120°C, the reaction pressure is maintained at 1.2Mpa, and a hydrogenation reduction reaction is started to obtain an o-aminophenol feed liquid;

[0122] Filtration and crystallization: After the reduction reaction is completed, the o-aminophenol liquid is pumped to the crystallization kettle, cooled to -10°C for crystallization and then centrifuged; the centrifuged mother liquor enters the static tank; the o-aminophenol wet material obtained after centrifugation is sent to the drying process;

[0123] Wet material drying: The o-aminophenol wet material obtained by centrifugation was dried by air flow, with the drying temperature maintained at 80°C and slight negative pressure, to finally obtain an off-white crystalline powder sample with a purity of 99.9% and a total yield of 81%.

[0124] Separation of mother liquor and mother liquor recycling: The mother liquor in the standing tank is allowed to stand for 20 minutes and then separated into layers. The upper layer is an organic phase containing 80% of n-butanol in the recovered mother liquor, and the lower layer is an aqueous phase containing 7% of n-butanol. The aqueous phase is discharged to a liquid storage tank for temporary storage, and the recovered mother liquor is decolorized and then participates in the next hydrogenation reduction reaction.

[0125] The samples collected from the above embodiments and comparative examples were subjected to liquid chromatography component analysis to calculate the yield and purity of o-aminophenol. The data are shown in the following table.

[0126] Table 1 shows the purity and yield of o-aminophenol obtained in each embodiment and each comparative example.

[0127] Table 1 Yield and purity of o-aminophenol obtained in each embodiment and each comparative example

[0128]

[0129]

[0130] The experimental results obtained by the above embodiments and comparative examples show that:

[0131] The purity of o-aminophenol obtained by catalytic hydrogenation with methanol as solvent is about 99.3%, and the yield is about 89%, but the color is reddish, the yield is low, and methanol is highly toxic to the human body. Considering safety, methanol is generally not selected as a solvent in actual production;

[0132] The purity of o-aminophenol obtained by catalytic hydrogenation with ethanol as solvent is about 99.5%, the yield is about 88%, and the color is white to light gray. However, the ethanol and water in the mother liquor can be miscible in any proportion and cannot be quickly separated. If the mother liquor is directly used for reduction production, each time it is used, the newly generated water remains in the mother liquor, which will cause the ethanol concentration in the mother liquor to become lower and lower, thereby affecting the hydrogenation reaction. Moreover, the solubility of o-aminophenol in the mother liquor is also reduced due to the low ethanol concentration, resulting in a decrease in single-pot output and a decrease in the yield of o-aminophenol. The mother liquor must be distilled and purified to remove ethanol and then used as a solvent. Mother liquor distillation will greatly increase energy consumption. At the same time, during high-temperature distillation, the uncrystallized o-aminophenol in the mother liquor will be oxidized into harmful and hazardous waste, which not only reduces the yield of o-aminophenol, but also increases environmental protection treatment costs.

[0133] The purity of o-aminophenol obtained by catalytic hydrogenation using 80% n-butanol as a solvent is 99.9%. Although the initial yield is about 81%, in the subsequent process, by applying the mother liquor and using "50% mother liquor + 50% n-butanol" as a solvent, the purity of o-aminophenol obtained is 99.7%, and the yield can reach 94.2%; using "70% mother liquor + 30% n-butanol" as a solvent, the purity of o-aminophenol obtained is 99.5%, and the yield can reach 96.1%; using "100% mother liquor" as a solvent, the purity of o-aminophenol obtained is 99.3%, and the yield can reach 97.5%.

[0134] Compared with Comparative Examples 1 and 2, in Examples 2 to 4, the crystallization mother liquor is directly used in the hydrogenation process after being layered, which greatly reduces the time and process required for solvent recovery, improves production efficiency, and greatly reduces energy consumption; the uncrystallized o-ammonia is directly brought back to the hydrogenation reaction by the recycled solvent, which reduces product loss and improves the o-ammonia yield; and reduces the generation of harmful wastes such as tar generated by residual o-aminophenol in the mother liquor during the high-temperature distillation process.

[0135] Comparative Example 3 is compared with Comparative Example 2. It can be seen that the ethanol mother liquor in Comparative Example 2 is applied mechanically. In order to maintain the optimal ratio of ethanol in the solvent and the total volume of the solvent, it is necessary to re-formulate the mother liquor with 95% mass fraction of ethanol-water solvent, and the final o-aminophenol purity obtained reaches 99.4%, and the yield is 91.3%, but the maximum application ratio of the ethanol mother liquor is only 40%. By comparing with Example 2-5, it can be known that when the n-butanol mother liquor application ratio is 100%, the o-aminophenol purity reaches 99.3%, and the yield is 97.5%, but considering the loss in the actual production process, the n-butanol mother liquor application ratio is preferably 90% at most. Comprehensively comparing and analyzing the above, and combining the actual production situation, compared with the n-butanol mother liquor application effect, the direct application effect of the ethanol mother liquor is not good, and it is not suitable for industrial production.

[0136] By comparing Examples 1 to 11 with Comparative Example 4, it can be seen that the solvent used in Comparative Example 4 is pure butanol. Although the purity of the obtained o-aminophenol reaches 99.9%, the yield is only 81%. Similarly, the yield of Comparative Example 4 is low by recycling the mother liquor, and the technical solution of Comparative Example 4 is less effective.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing o-aminophenol using n-butanol as solvent, characterized in that: The method comprises: Reduction reaction: o-nitrophenol is reduced in n-butanol-water solvent by adding hydrogen gas under the action of a catalyst to obtain o-aminophenol liquid; Crystallization: crystallizing the o-aminophenol liquid to obtain o-aminophenol wet material and mixed mother liquor; Mixed mother liquor separation: separating the mother liquor to obtain a recovered mother liquor containing n-butanol and an aqueous phase; Mother liquor recycling: the recovered mother liquor containing n-butanol is used as the solvent for the reduction reaction.

2. The method according to claim 1, characterized in that In the reduction reaction, the volume ratio of the n-butanol-water solvent to the mass ratio of o-nitrophenol is 3-5:1, and the mass fraction of n-butanol in the n-butanol-water solvent is 60%-85%.

3. The method according to claim 1, characterized in that The mixed mother liquor separation method is as follows: the mixed mother liquor is allowed to stand for 10 minutes to 30 minutes, and after the mixed mother liquor is layered, a recovered mother liquor containing n-butanol and an aqueous phase are obtained.

4. The method according to claim 3, characterized in that The content of n-butanol in the recovered mother liquor containing n-butanol is 70% to 85%.

5. The method according to claim 1, characterized in that The method further comprises: drying the o-aminophenol wet material to obtain the o-aminophenol finished product.

6. The method according to claim 1, characterized in that The aqueous phase obtained in the crystallization step is distilled to obtain water and a n-butanol solution, and the n-butanol solution is used to replenish the solvent loss of the reduction reaction.

7. The method according to claim 1, characterized in that The solvent in the reduction reaction consists of 50% to 90% by mass of recovered mother liquor and 50% to 10% by mass of n-butanol-water solvent.

8. The method according to claim 1, characterized in that The solvent in the reduction reaction is 100% recycled mother liquor.

9. The method according to claim 1, characterized in that: In the mixed mother liquor separation step, the aqueous phase contains n-butanol and water and is temporarily stored in a liquid storage tank until the volume of the liquid storage tank is greater than 5m 3 When the product is distilled, it enters the distillation tower for distillation operation.

10. The method according to claim 9, characterized in that The distillation process controls the top temperature of the distillation tower to 91±2° C. The distilled water is collected and used as process water, and the obtained n-butanol is recovered for the reduction reaction.

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