A method and system for co-producing N-methylaniline and N-methylindole

Abstract

The present invention provides a method and system for co-producing N-methylaniline and N-methylindole. The method comprises: a first Cu-based catalyst catalyzes a first reaction between aniline and methanol to obtain a first gaseous mixed system containing N-methylaniline; ethylene glycol is introduced into the first gaseous mixed system, and part of the N-methylaniline and ethylene glycol in the first gaseous mixed system undergo a second reaction under the catalysis of a second Cu-based catalyst to be converted into N-methylindole, and finally a second gaseous mixed system containing N-methylaniline and N-methylindole is obtained; the second gaseous mixed system is condensed, flashed and distilled to separate N-methylaniline and N-methylindole. In the co-production method provided by the present invention, by means of a two-stage reaction, not only N-methylaniline is synthesized with high efficiency and low cost, but also co-production of N-methylaniline and N-methylindole is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemical preparation, and in particular to a method and system for co-producing N-methylaniline and N-methylindole. Background Art

[0002] N-methylaniline is an important organic compound, which is widely used in many fields such as medicine, dyes, pesticides, etc. At present, the methods for producing N-methylaniline mainly include high-pressure reactor catalytic method, separation and extraction method from tar, nitrobenzene and methanol one-pot method and aniline and methanol production method. Among them, the high-pressure reactor catalytic method mostly uses toluene (hazardous chemicals) as raw material, and the synthesis method is complicated, the yield is poor, and the industrialization prospect is not good; the method of producing N-methylaniline with aniline and methanol as raw materials is mostly prepared by gas phase method, specifically, the chemical reaction between aniline and methanol under the catalytic action of copper zinc chromium catalyst, and the by-product in the product is N, N-dimethylaniline. Since the boiling point difference between N, N-dimethylaniline and N-methylaniline is only 3 °C, the crude product needs to use refined separation equipment to first remove methanol, water, aniline and N, N-dimethylaniline, and finally extract N-methylaniline with extremely high purity through vacuum distillation technology; this leads to the high cost of N-methylaniline synthesis. However, there is currently no process for the co-production of N-methylaniline and N-methylindole, which is not conducive to actual production capacity regulation. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention provides a method and system for co-producing N-methylaniline and N-methylindole, which reduces the synthesis cost of N-methylaniline and obtains N-methylindole, a chemical with high value. The specific content of the invention is as follows:

[0004] In a first aspect, the present invention provides a method for co-producing N-methylaniline and N-methylindole, the method comprising:

[0005] The first Cu-based catalyst catalyzes a first reaction between aniline and methanol to obtain a first gaseous mixed system containing N-methylaniline;

[0006] Ethylene glycol is introduced into the first gaseous mixed system, and part of the N-methylaniline in the first gaseous mixed system reacts with the ethylene glycol under the catalysis of a second Cu-based catalyst to be converted into N-methylindole, thereby finally obtaining a second gaseous mixed system containing N-methylaniline and N-methylindole;

[0007] Condensing, flashing and rectifying the second gaseous mixed system to separate the N-methylaniline and the N-methylindole;

[0008] Wherein, the molar ratio of the aniline to the methanol is 1:2 to 1:4, and the molar ratio of the ethylene glycol to the aniline is 1:4 to 1:8.

[0009] Optionally, in the first reaction, the reaction temperature is 200-250°C; the reaction pressure is 0-0.5 MPa;

[0010] In the second reaction, the reaction temperature is 220-270°C; the reaction pressure is 0-0.5 MPa; the feed space velocity of ethylene glycol is 0.06-0.1 h -1 .

[0011] Optionally, before the first Cu-based catalyst catalyzes the first reaction between aniline and methanol, the method further comprises: mixing aniline, methanol and water, preheating and gasifying them, and then catalytically contacting them with the first Cu-based catalyst to perform the first reaction; wherein,

[0012] The feed space velocity of the aniline is 0.2 to 0.8 h -1 ;

[0013] The feed space velocity of the water is 0 to 0.2 h -1 .

[0014] Optionally, before introducing ethylene glycol into the first gaseous mixed system, the method further comprises: mixing ethylene glycol with water, preheating and gasifying the mixture, and then mixing the mixture with the first gaseous mixed system; wherein,

[0015] The feed space velocity of ethylene glycol is 0.06 to 0.1 h -1 ;

[0016] The feed space velocity of the water is 0 to 0.15 h -1 .

[0017] Optionally, the first Cu-based catalyst catalyzes the first reaction to produce N-methylaniline;

[0018] The first Cu-based catalyst is formed by CuO and a first promoter metal loaded on a carrier; wherein,

[0019] The first auxiliary metal is selected from at least one of Ce, La, Zr, Mo, Y, Co and Mg, with a mass ratio of 10-20%;

[0020] The mass proportion of the CuO is 30-45%; the carrier includes copper aluminum spinel, silica, alumina, carbon black or zeolite molecular sieve.

[0021] Optionally, the second Cu-based catalyst catalyzes the second reaction to produce N-methylindole;

[0022] The second Cu-based catalyst is formed by CuO and a second promoter metal, or CuO, a second promoter metal and a third promoter metal supported on a carrier; wherein,

[0023] The carrier is selected from copper aluminum spinel, silica, alumina, carbon black or zeolite molecular sieve;

[0024] The second auxiliary metal is Zr, and the third auxiliary metal is selected from at least one of Mg, Zn, Ce, Mo, La, Y, Cr, Ni and Co;

[0025] In the second Cu-based catalyst, the mass proportion of the second auxiliary metal is 1-10%, the mass proportion of the third auxiliary metal is 0-10%, and the mass proportion of CuO is 10-30%.

[0026] Optionally, the condensation, flash evaporation and rectification treatment comprises:

[0027] condensing the second gaseous mixed system and collecting the liquid portion to obtain a first crude product;

[0028] Flash distilling the first crude product to remove impurities, collecting the liquid portion, and obtaining a second crude product;

[0029] performing a first distillation treatment on the second crude product to separate the light components of the raw materials and leave a mixed product;

[0030] The mixed product is subjected to a second distillation treatment to separate a mixture of N-methylaniline and N-methylindole;

[0031] The N-methylindole mixture is subjected to a third distillation treatment to separate the N-methylindole from heavy components.

[0032] In a second aspect, the present invention provides a system for co-producing N-methylaniline and N-methylindole, wherein the system is used to perform the method for co-producing N-methylaniline and N-methylindole described in the first aspect, comprising a reaction device and a separation device connected in sequence, wherein the reaction device comprises a first reaction zone and a second reaction zone; wherein

[0033] The first reaction zone is configured to catalyze a first reaction between aniline and methanol using a first Cu-based catalyst to obtain a first gaseous mixed system containing N-methylaniline;

[0034] The second reaction zone is configured to catalyze a second reaction of a portion of N-methylaniline in the gaseous mixed system with ethylene glycol using a second Cu-based catalyst to convert the portion into N-methylindole, thereby finally obtaining a second gaseous mixed system containing N-methylaniline and N-methylindole;

[0035] The separation device is configured to perform condensation, flash evaporation and rectification on the second gaseous mixed system to separate the N-methylaniline and the N-methylindole;

[0036] Wherein, the molar ratio of the aniline to the methanol is 1:2 to 1:4, and the molar ratio of the ethylene glycol to the aniline is 1:4 to 1:8.

[0037] Optionally, the system further comprises a first preheating device and a second preheating device; wherein,

[0038] The first preheating device is connected to the first reaction zone, and the first preheating device is configured to heat and gasify aniline, methanol and water, and after obtaining a gaseous fluid, input it into the first reaction zone for a first reaction;

[0039] The second preheating device is connected to the second reaction zone, and is configured to heat and gasify ethylene glycol and water to obtain a gaseous fluid, which is then input into the second reaction zone to mix with the first gaseous mixed system for a second reaction.

[0040] Optionally, the system further comprises a first mixing device and a second mixing device; wherein,

[0041] The first mixing device is connected to the first preheating device, and the first mixing device is configured to fully mix aniline, methanol and water, and then input them into the first preheating device for heating and gasification;

[0042] The second mixing device is communicated with the second preheating device, and the second mixing device is configured to fully mix ethylene glycol and water and then input the mixed mixture into the second preheating device for heating and gasification.

[0043] Optionally, the separation device includes a condenser, a flash tank, a first distillation tower, a second distillation tower and a third distillation tower; wherein,

[0044] The condenser is connected to the second reaction zone and is used to condense the second gaseous mixed system and collect the bottom liquid portion as the first crude product;

[0045] The flash tank is connected to the condenser and is used to flash the first crude product to remove impurities and collect the bottom liquid portion as the second crude product;

[0046] The first distillation tower is connected to the flash tank and is used to perform distillation treatment on the second crude product to separate the light components of the raw materials and leave the remaining mixed products;

[0047] The second distillation tower is connected to the first distillation tower and is used to perform distillation treatment on the mixed product to separate the N-methylaniline and N-methylindole mixture;

[0048] The third distillation tower is connected to the second distillation tower and is used to perform distillation treatment on the N-methylindole mixture to separate the N-methylindole from heavy components.

[0049] Optionally, the first distillation tower, the second distillation tower and the third distillation tower are all packed towers, the number of theoretical plates is 10 to 50, the reflux ratio is controlled at 0.5 to 20, and the tower top pressure is 0.01 to 0.1 MPa.

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] The present invention provides a method for co-producing N-methylaniline and N-methylindole. The method comprises the following steps: a first Cu-based catalyst is used to catalyze a first reaction between aniline and methanol to obtain a first gaseous mixed system containing N-methylaniline; ethylene glycol is introduced into the first gaseous mixed system, and a part of the N-methylaniline in the first gaseous mixed system and the ethylene glycol are catalyzed by a second Cu-based catalyst to undergo a second reaction to be converted into N-methylindole, thereby finally obtaining a second gaseous mixed system containing N-methylaniline and N-methylindole; and the second gaseous mixed system is condensed, flashed, and heated to a temperature of 100 °C. The N-methylaniline and the N-methylindole are separated by distillation and rectification. In the co-production method provided by the present invention, by means of a two-stage reaction, in the first stage, aniline and methanol are used as raw materials, combined with a first Cu-based catalyst, to efficiently prepare N-methylaniline; in the second stage, the product obtained from the first stage reaction and newly added ethylene glycol are continuously used as raw materials, and N-methylaniline and ethylene glycol are synthesized into N-methylindole under the action of the second Cu-based catalyst; by controlling the process parameters of the two-stage reaction, the co-production of N-methylaniline and N-methylindole can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 A flow chart of a method for co-producing N-methylaniline and N-methylindole provided in an embodiment of the present invention is shown;

[0054] Figure 2 A schematic diagram of a system for co-producing N-methylaniline and N-methylindole provided in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work belong to the scope of protection of the present invention.

[0056] In the embodiment, no specific experimental steps or conditions are indicated, and the operation or conditions of the conventional experimental steps described in the prior art in this field can be carried out. The reagents used and other instruments that do not indicate the manufacturer are conventional reagent products that can be obtained commercially. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0057] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the description of the present invention.

[0058] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0059] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0060] Before describing in detail the method and system for co-producing N-methylaniline and N-methylindole provided by the present invention, it is necessary to describe the related technologies as follows:

[0061] In the existing method of preparing N-methylaniline in the gas phase using aniline and methanol as raw materials, the by-product N,N-dimethylaniline is mainly obtained by secondary substitution of the product (N-methylaniline) with methanol; the reaction equation is as follows:

[0062] C6H5-NHCH3+CH3OH→C6H5-N(CH3)2+H2O

[0063] Due to the formation of by-product N,N-dimethylaniline, the yield and purification cost of N-methylaniline are high.

[0064] At present, the synthesis of N-methylindole mainly adopts the following two methods:

[0065] 1) Using indole as the raw material, the indole NH is directly methylated by methyl halide; the yield of N-methylindole synthesized by methylation reaction is relatively high, which can reach 99%, but the raw material indole is expensive, and the methyl halide is expensive and genotoxic, so this synthesis method has great limitations.

[0066] 2) Synthesis of N-methylindole from ethylene glycol and N-methylaniline in one step under metal catalysis; specifically, N-methylaniline and ethylene glycol are used as substrates, palladium-loaded catalyst Pd / Al2O3 is used as catalyst, TsOH and ZnO are used as co-catalysts to synthesize N-methylindole. However, the yield of N-methylindole in the above technical solution does not exceed 40%; and the separation and purification of the synthesized N-methylindole is achieved by column chromatography, which is not conducive to industrial production.

[0067] In theory, both N-methylaniline and N-methylindole belong to the alcohol amine reaction mechanism. There have been some preliminary theoretical studies, but there is still a lack of in-depth understanding of the specific reaction pathways, intermediate structures and other details of the synthesis of N-methylaniline or N-methylindole under different catalyst systems. If the three raw materials of aniline, methanol and ethylene glycol are reacted together without control through the process system, it is inevitable that other by-products such as indole and N, N-dimethylaniline will be produced.

[0068] Based on the above problems, the present invention considers that if N-methylaniline synthesized from aniline and methanol in one step is further reacted with ethylene glycol, it can greatly consume excess N-methylaniline, while avoiding further conversion of N-methylaniline into byproduct N,N-dimethylaniline, and synthesizing high-value chemical N-methylindole. On this basis, the present invention has found through a large number of experimental attempts that a first copper-based catalyst and a second copper-based catalyst composed of a specific component can achieve the co-production of N-methylaniline or N-methylindole in combination with specific process conditions. Specifically, the present invention can achieve the co-production of N-methylaniline and N-methylindole by regulating aniline, methanol and ethylene glycol as reaction raw materials, and coordinating suitable process flows and catalysts.

[0069] The co-production process provided by the present invention can adjust the yield of N-methylaniline or N-methylindole in the co-production process according to production capacity requirements without requiring additional device improvements.

[0070] The specific implementation contents are as follows:

[0071] In a first aspect, the present invention provides a method for co-producing N-methylaniline and N-methylindole. Figure 1 The flow chart of the method for co-producing N-methylaniline and N-methylindole provided in the embodiment of the present invention is shown as follows: Figure 1 As shown, the method includes:

[0072] S1, a first Cu-based catalyst catalyzes a first reaction between aniline and methanol to obtain a first gaseous mixed system containing N-methylaniline;

[0073] S2, ethylene glycol is introduced into the first gaseous mixed system, and part of the N-methylaniline in the first gaseous mixed system and the ethylene glycol are subjected to a second reaction under the catalysis of a second Cu-based catalyst to be converted into N-methylindole, thereby finally obtaining a second gaseous mixed system containing N-methylaniline and N-methylindole;

[0074] S3, condensing, flashing and rectifying the second gaseous mixed system to separate the N-methylaniline and the N-methylindole.

[0075] In specific implementation, the present invention provides a two-stage reaction: the first stage reaction (first reaction) uses aniline and methanol as raw materials, combines the catalytic effect of the first Cu-based catalyst, and efficiently reacts to generate N-methylaniline at a reaction temperature of 200-250° C. and a reaction pressure of 0-0.5 MPa; in this process, the molar ratio of aniline to methanol is 1:2-1:4, that is, methanol is in an excess state, which makes the aniline conversion rate very high. In the first stage reaction, the aniline conversion rate can reach more than 90%.

[0076] Furthermore, the high conversion rate of aniline in the first stage reaction also relies on the correct selection of the catalyst. The first Cu-based catalyst used in the present invention is formed by CuO and a first auxiliary metal loaded on a carrier, wherein the mass proportion of CuO is 30-45%; the first auxiliary metal is selected from at least one of Ce, La, Zr, Mo, Y, Co and Mg, accounting for 10-20% by mass; the rest is a carrier, and the carrier includes copper aluminum spinel, silica, alumina, carbon black or zeolite molecular sieve.

[0077] As an example, the first Cu-based catalyst used in the first stage reaction of the present invention is formed by CuO, Mg and Co loaded on a copper-aluminum spinel carrier, wherein the mass proportion of CuO is 40%, and the mass proportion of the first auxiliary metal Mg and Co is 15%; as another example, the first Cu-based catalyst used in the first stage reaction of the present invention is formed by CuO and Zr loaded on a copper-aluminum spinel carrier, wherein the mass proportion of CuO is 30%, and the mass proportion of Zr is 15%; as another example, the first Cu-based catalyst used in the first stage reaction of the present invention is formed by CuO, Mg and Zr loaded on a copper-aluminum spinel carrier, wherein the mass proportion of CuO is 33%, and the mass proportion of Mg and Zr is 12%.

[0078] In some embodiments, in order to improve the efficiency of the first reaction, the raw materials aniline and methanol can be mixed with water, preheated and gasified before contacting the Cu-based catalyst, and then contacted with the first Cu-based catalyst to carry out the first reaction. The first reaction is carried out in an environment containing water vapor. The presence of water vapor can effectively reduce the carbon deposition of the catalyst and extend the service life of the catalyst. The preheating temperature is 180-200 ° C, and the feed space velocity of aniline is 0.2-0.8h -1 , specifically 0.2 h -1 , 0.3 h -1 , 0.4 h -1 , 0.5 h -1 , 0.6 h -1 , 0.7 h -1 and 0.8 h -1 , preferably 0.5 h -1 ; The feed space velocity of water is 0~0.2 h -1 The vaporized aniline and methanol are efficiently converted into N-methylaniline with little by-products under the action of Cu-based catalyst.

[0079] In the specific implementation, the first gaseous mixed system containing N-methylaniline obtained in the first reaction continues to be used as the reaction raw material of the second reaction (second reaction), and ethylene glycol is further added, so that the N-methylaniline in the first gaseous mixed system and ethylene glycol react to generate N-methylindole under the action of the second Cu-based catalyst; it should be noted that the second Cu-based catalyst used in the second reaction is different from the first Cu-based catalyst used in the first reaction. The second Cu-based catalyst used in the second reaction is formed by CuO and a second auxiliary metal, or CuO, a second auxiliary metal and a third auxiliary metal loaded on a carrier; wherein the carrier is selected from copper aluminum spinel, silica, alumina, carbon black or zeolite molecular sieve; the second auxiliary metal is Zr, and the third auxiliary metal is selected from at least one of Mg, Zn, Ce, Mo, La, Y, Cr, Ni and Co; the mass proportion of the second auxiliary metal is 1-10%, the mass proportion of the third auxiliary metal is 0-10%, and the mass proportion of CuO is 10-30%.

[0080] As an example, the second Cu-based catalyst used in the second stage reaction of the present invention is formed by CuO and Zr loaded on a copper aluminum spinel carrier, wherein the mass proportion of CuO is 30% and the mass proportion of Zr is 8%; as another example, the second Cu-based catalyst used in the second stage reaction of the present invention is formed by CuO and Mg, Zr loaded on a copper aluminum spinel carrier, wherein the mass proportion of CuO is 25%, and the mass proportion of Mg and Zr is 15%; the second Cu-based catalyst used in the second stage reaction of the present invention is formed by CuO and metal additives Zr and Co loaded on a silica carrier, wherein the mass proportion of CuO is 30%, the mass proportion of the metal additives Zr and Co is 20%, and the mass proportion of the silica carrier is 50%.

[0081] Since the first gaseous mixed system also contains a small amount of raw gas such as aniline and methanol, in the second reaction, aniline may theoretically react with ethylene glycol to form indole, but since the electron cloud density of nitrogen atoms in N-methylaniline is higher than that of aniline, N-methylaniline reacts with ethylene glycol preferentially to form N-methylindole. In addition, the temperature required for synthesizing indole (280°C, 290°C, 300°C) is relatively high for synthesizing N-methylindole. Therefore, the present invention controls the reaction temperature of the second reaction to be 220-270°C and the reaction pressure to be 0-0.5 MPa, so that the reaction proceeds in the direction of easily generating N-methylindole.

[0082] Similarly, in the second reaction, N-methylaniline and the remaining methanol may also generate N, N-dimethylaniline. The present invention has been verified by a large number of experiments, and it is concluded that when the reaction temperature of the second reaction is 220-270°C and the reaction pressure is 0-0.5 MPa, the main product generated is N-methylindole, and N, N-dimethylaniline and indole are basically not generated; on the other hand, the unconverted aniline can continue to react with the remaining methanol in the second reaction process to generate N-methylaniline. Therefore, the method of the present invention can achieve a higher yield of N-methylaniline, and at the same time, the product structure is diversified, the circulation amount of aniline is reduced, and N-methylindole is also co-produced.

[0083] In some embodiments, in order to improve the efficiency of the second reaction, ethylene glycol is first subjected to gasification treatment before contacting the first gaseous mixed system. Specifically, ethylene glycol can be first mixed with water, preheated and gasified, and then mixed with the first gaseous mixed system; wherein the heating temperature of the preheating gasification is 200-250 °C, and the feed space velocity of ethylene glycol is 0.06-0.1 h -1 , specifically 0.06 h -1 , 0.07 h -1 , 0.08 h -1 , 0.09 h -1 , 0.1 h -1 , preferably 0.08 h -1 ; The feed space velocity of water is 0~0.15 h -1 The second reaction is carried out in a water vapor environment, which can effectively extend the service life of the second catalyst; the vaporized ethylene glycol contacts the N-methylaniline in the first gaseous mixed system in the second reaction, and is efficiently converted into N-methylindole under the action of the second Cu-based catalyst with few by-products.

[0084] In some embodiments, the second gaseous mixed system obtained after the second reaction is completed is subjected to condensation, flash evaporation and distillation treatment to separate the target products N-methylaniline and the N-methylindole; this process specifically includes: the second gaseous mixed system is condensed by a condenser, and then converted from a gaseous state into a partial liquid product, the liquid component condensed by the condenser is sent to a flash evaporator, and is discharged after flash evaporation, and the gas can be collected, the bottom product of the flash tank is sent to a first distillation tower for separation, the light components (aniline and methanol) at the top of the tower are recycled as raw materials, the bottom product (N-methylaniline, N-methylindole and other heavy components) is further sent to a second distillation tower for separation, and N-methylaniline is collected at the top of the tower; the bottom product of the second distillation tower is further sent to a third distillation tower for separation, and other heavy components are separated from N-methylindole to obtain N-methylindole.

[0085] The method for co-producing N-methylaniline and N-methylindole provided by the present invention achieves flexible adjustment of the terminal product proportions of N-methylindole and N-methylaniline products within a certain range (N-methylindole accounts for 10-22% and N-methylaniline accounts for 65-75%) by regulating the molar ratio of aniline to methanol (1:2-1:4) and the molar ratio of ethylene glycol to aniline (1:4-1:8).

[0086] In a second aspect, the present invention also provides a system for co-producing N-methylaniline and N-methylindole, see Figure 2 The system schematic diagram shown is as follows: Figure 2 As shown, the system for co-producing N-methylaniline and N-methylindole includes a reaction device R and a separation device H, wherein the reaction device R is divided into a first reaction zone R1 and a second reaction zone R2; wherein the first reaction zone R1 is configured to catalyze a first reaction between aniline and methanol with a first Cu-based catalyst to obtain a first gaseous mixed system containing N-methylaniline; the second reaction zone R2 is configured to catalyze a second reaction between part of the N-methylaniline in the gaseous mixed system and ethylene glycol with a second Cu-based catalyst to convert the part into N-methylindole, and finally obtain a second gaseous mixed system containing N-methylaniline and N-methylindole; the separation device H is configured to condense, flash and distill the second gaseous mixed system to separate N-methylaniline and N-methylindole.

[0087] In specific implementation, the system for co-producing N-methylaniline and N-methylindole provided by the present invention adopts a two-stage reactor to respectively carry out a first reaction and a second reaction, that is, the first reaction is carried out in a first reaction zone R1 of a reaction device R, and the first reaction zone R1 of the reaction device R is provided with a raw material inlet for introducing aniline and methanol into the first reaction zone R1, so that the first reaction uses aniline and methanol as raw materials, and combines the catalytic effect of the first Cu-based catalyst filled in the first reaction zone R1, and efficiently reacts to generate N-methylaniline at a reaction temperature of 200 to 250° C. and a reaction pressure of 0 to 0.5 MPa; the molar ratio of aniline to methanol entering the first reaction zone R1 is 1:2 to 1:4, that is, methanol is in an excess state, which makes the aniline conversion rate very high. In the first reaction zone R1, the aniline conversion rate can reach more than 90%.

[0088] See also Figure 2In order to improve the efficiency of the first reaction, the raw materials aniline and methanol are first gasified before entering the first reaction zone R1. Specifically, the aniline and methanol involved in the reaction and a certain amount of water are input into the first preheating device E1, where they are heated to 180-200 °C for gasification. The gasified aniline and methanol are then input into the first reaction zone R1 of the reactor R with water vapor, and are efficiently converted into N-methylaniline with less by-products under the action of the first Cu-based catalyst. The presence of water vapor in the first reaction zone R1 can alleviate the carbon deposition problem of the catalyst during the reaction.

[0089] See also Figure 2 Before being input into the first preheating device E1, aniline, methanol and a certain amount of water may be fully mixed in the first mixing device M1 and then input into the first preheating device E1 for heating and gasification treatment.

[0090] Furthermore, the first gaseous mixed system containing N-methylaniline obtained in the first reaction zone R1 enters the second reaction zone R2 and continues to be used as a reaction raw material for the second stage reaction (second reaction), and ethylene glycol is added to the second reaction zone R2, so that in the second reaction zone R2, the N-methylaniline in the first gaseous mixed system reacts with ethylene glycol under the action of the second Cu-based catalyst loaded in the second reaction zone R2 to generate N-methylindole.

[0091] See also Figure 2 In order to improve the efficiency of the second reaction, the ethylene glycol is first gasified before entering the second reaction zone R2, specifically including: the ethylene glycol participating in the reaction and a certain amount of water are introduced into the second preheating device E2, heated to 200-250 °C for gasification, and then introduced into the second reaction zone R2 after gasification, contacted with the N-methylaniline in the first gaseous mixed system, and efficiently converted into N-methylindole under the action of the second Cu-based catalyst with less by-products; the presence of water vapor in the second reaction zone R2 can also effectively alleviate the problem of carbon deposition of the catalyst during the reaction.

[0092] See also Figure 2 Before being input into the second preheating device E2, ethylene glycol and water can be fully mixed in the first mixing device M2 and then input into the first preheating device E2 for heating and gasification treatment.

[0093] See also Figure 2The separation device H further includes a condenser F, a flash tank S, a first distillation tower T1, a second distillation tower T2 and a third distillation tower T3. The condenser F is connected to the second reaction zone R2, and is used for condensing the second gaseous mixed system and collecting the bottom liquid part as the first crude product; the flash tank S is connected to the bottom of the condenser F, and is used for flashing the first crude product to remove the hydrogen and part of the water mixed therein, and collecting the bottom liquid part as the second crude product; the first distillation tower T1 is connected to the bottom of the flash tank S, and is used for distilling the second crude product, separating the raw material light components (aniline, methanol and ethylene glycol) therein at the top of the tower, and the remaining mixed product formed by N-methylaniline and N-methylindole at the bottom of the tower; the bottom of the second distillation tower T2 is connected to the first distillation tower T1, and is used for distilling the mixed product to separate N-methylaniline, remaining N-methylindole and a mixture of heavy components; the third distillation tower T3 is connected to the bottom of the second distillation tower T2, and is used for distilling the N-methylindole mixture to separate N-methylindole from the heavy components.

[0094] In the above separation and purification process, the second gaseous mixed system is condensed by the condenser F and converted from a gaseous state into a partial liquid product. The liquid component condensed by the condenser F is sent to the flash evaporator S, vented after flash evaporation, and the gas can be collected. The bottom product of the flash tank S is sent to the first distillation tower T1 for separation, and the light components (aniline and methanol) at the top of the tower are recycled as raw materials. The bottom product (N-methylaniline and N-methylindole) is further sent to the second distillation tower T2 for separation, and N-methylaniline is collected. The bottom product is further sent to the third distillation tower T3 for separation, and N-methylindole is collected.

[0095] It should be noted that the first reaction zone R1 and the second reaction zone R2 in the reaction device have independent temperature control components.

[0096] It should be noted that when the first reaction zone R1 is a fixed bed, the second reaction zone R2 should also be a fixed bed.

[0097] It should be noted that the first Cu-based catalyst and the second Cu-based catalyst filled in the first reaction zone R1 and the second reaction zone R2 can be reduced and activated before use. The specific reduction method is as follows: reduction is carried out in an N2 atmosphere containing H2, the volume content of hydrogen in the H2 / N2 mixed gas is 1-20%, and the space velocity is 100-1000 h -1 , the reduction temperature is 100-300 °C, and the reduction time is 1-50 h. During the reaction, when the Cu-based catalyst is deactivated or its activity is reduced, a regeneration gas is introduced into the reactor R for in-situ regeneration. The regeneration gas is air or nitrogen containing oxygen, and the gas space velocity is 50-1000 h -1The catalyst is heated and kept in situ at a heating rate of 10 to 20 °C / h to 200 to 400 °C and kept warm for 2 to 20 h. After regeneration, the catalyst is reduced according to the reduction method and then continued to be used for catalytic reaction.

[0098] In order to enable those skilled in the art to more clearly understand the present invention, the method and system for co-producing N-methylaniline and N-methylindole according to the present invention are now described in detail through the following examples.

[0099] Example 1

[0100] use Figure 2 The system schematic diagram shown in the figure shows that N-methylaniline and N-methylindole are co-produced under the following reaction conditions.

[0101] The first reaction zone R1 is filled with the first Cu-based catalyst, and the second reaction zone R2 is filled with the second Cu-based catalyst. The Cu-based catalyst loading amount is 50 mL, and the catalyst is reduced in a nitrogen atmosphere containing hydrogen. The first Cu-based catalyst is formed by CuO and the first auxiliary metal Mg and Co loaded on a copper-aluminum spinel carrier, wherein the mass proportion of CuO is 40%, and the mass proportion of the first auxiliary metal Mg and Co is 15%. The second Cu-based catalyst is formed by CuO and Zr loaded on a copper-aluminum spinel carrier, wherein the mass proportion of CuO is 24%, and the mass proportion of metal (Zr) is 5%. The first Cu-based catalyst and the second Cu-based catalyst are reduced under a mixed gas of nitrogen 250 mL / min and hydrogen 5 ml / min, and the air velocity is 306 h -1 , reduction temperature is 150 ℃, and reduction time is 10h.

[0102] After the reduction was completed, the raw materials aniline and methanol were transported to the reaction mixer M1 with a plunger pump at a molar ratio of 1:2, and the liquid space velocity of aniline was maintained at 0.5 h -1 , use a plunger pump to press the water for 0.1 h -1 The air velocity is injected into the mixer, and then the mixture of the two raw materials and water enters the preheater E1 for gasification. The temperature of the preheater E1 is 200 °C. The gasified aniline, methanol and water enter the first reaction zone. The reaction temperature is 230 °C and the reaction pressure is 0.2 MPa, and a gas-solid phase reaction is carried out with the first Cu-based catalyst. Then the gaseous phase flow from the first reaction zone R1 enters the second reaction zone R2 and contacts with the ethylene glycol raw material. The molar ratio of the ethylene glycol feed amount in the second reaction zone R2 to the aniline feed amount in the first reaction zone R1 is 1:4. The water feed air velocity in the second reaction zone R2 is 0.1 h -1, after being mixed with ethylene glycol in the mixer M2, it enters the preheater E2 for preheating and vaporization at a preheating temperature of 220°C. The vaporized ethylene glycol and water enter the second reaction zone R2, and together with the gaseous material coming out of the first reaction zone R1, react in the second reaction zone R2 under the action of the second Cu-based catalyst at a reaction temperature of 260°C to generate products including N-methylaniline and N-methylindole.

[0103] The reaction product in the second reaction zone R2 is condensed by the condenser F and converted from a gaseous state to a partially liquid product. The gas and water vapor are discharged after flashing in the flash tank S to remove the hydrogen and part of the water contained therein. The hydrogen can be collected and reused. The bottom product of the flash tank S enters the first distillation tower T1 for separation. The first distillation tower T1 has 20 theoretical plates, a reflux ratio of 5, and a tower top pressure (absolute pressure) of 0.1 MPa. The light components (aniline, methanol and ethylene glycol) at the top of the tower are recycled as raw materials. The bottom product of the first distillation tower T1 is further fed into the second distillation tower T2. The second distillation tower T2 has 20 theoretical plates, a reflux ratio of 10, and a tower top pressure (absolute pressure) of 0.1 MPa to separate the N-methylaniline and N-methylindole mixture; the bottom product of the second distillation tower T2 is further fed into the third distillation tower T3. The third distillation tower T3 has 30 theoretical plates, a reflux ratio of 4, and a tower top pressure (absolute pressure) of 0.05. MPa, to obtain N-methylindole.

[0104] The products in the co-production system were sampled and analyzed, and the results showed that in the first reaction zone R1, the aniline conversion rate was 92%, and in the second reaction zone R2, the N-methylindole yield was 70% (calculated as ethylene glycol).

[0105] Example 2

[0106] According to the conditions and steps of Example 1, the first reaction zone R1 is filled with the first Cu-based catalyst, and the second reaction zone R2 is filled with the second Cu-based catalyst. The Cu-based catalyst loading amount is 60 mL, and the catalyst is reduced in a nitrogen atmosphere containing hydrogen. The first Cu-based catalyst is formed by CuO and the first auxiliary metal Mg and La loaded on a copper-aluminum spinel carrier, wherein the mass proportion of CuO is 40%, the mass proportion of auxiliary metals Mg and La is 10%, and the mass proportion of the copper-aluminum spinel carrier is 50%. The second Cu-based catalyst is composed of CuO, the second auxiliary metal and the third auxiliary metal loaded on the copper-aluminum spinel carrier, wherein the mass proportion of CuO is 22%, the mass proportion of the second auxiliary metal (Zr) is 5%, and the mass proportion of the third auxiliary metal (Mg, Zn) is 8%. The first Cu-based catalyst and the second Cu-based heterogeneous catalyst are reduced under a mixed gas of 380 mL / min of nitrogen and 20 ml / min of hydrogen, and the air velocity is 400 h -1 , reduction temperature is 150 ℃, and reduction time is 15 h.

[0107] After the reduction was completed, the raw materials aniline and methanol were transported to the reaction mixer M1 with a plunger pump at a molar ratio of 1:4, and the liquid space velocity of aniline was maintained at 0.4 h -1 , use a plunger pump to press the water for 0.05 h -1 The air velocity is injected into the mixer, and then the mixture of the two raw materials and water enters the preheater E1 for gasification. The temperature of the preheater E1 is 200 °C. The gasified aniline, methanol and water enter the first reaction zone R1. The reaction temperature is 250 °C and the reaction pressure is 0 MPa, and a gas-solid phase reaction is carried out with the first Cu-based catalyst. Then the gaseous phase flow from the first reaction zone R1 enters the second reaction zone R2 and contacts with the ethylene glycol raw material. The molar ratio of the ethylene glycol feed amount in the second reaction zone R2 to the aniline feed amount in the first reaction zone R1 is 1:8. The water feed air velocity in the second reaction zone R2 is 0.2 h -1 , mixed with ethylene glycol in mixer M2 and then enter preheater E2 for preheating and vaporization at a preheating temperature of 250°C. The vaporized ethylene glycol and water enter the second reaction zone R2 and react with the gaseous material from the first reaction zone R1 in the second reaction zone R2 under the action of a second Cu-based catalyst at a reaction temperature of 270°C to generate products including N-methylaniline and N-methylindole.

[0108] The reaction products in the second reaction zone R2 are condensed by the condenser F and converted from gaseous state to partially liquid products. The gas and water vapor are discharged after flashing in the flash tank S to remove the hydrogen and part of the water contained therein. The hydrogen can be collected and reused. The bottom product of the flash tank S enters the first distillation tower T1 for separation. The first distillation tower T1 has 15 plates, a reflux ratio of 5, and a top pressure (absolute pressure) of 0.1 MPa. The light components (aniline, methanol and ethylene glycol) at the top of the tower are recycled as raw materials. The bottom product of the first distillation tower T1 is further input into the second distillation tower T2. The second distillation tower T2 has 15 plates, a reflux ratio of 10, and a top pressure (absolute pressure) of 0.1 MPa, to separate the mixture of N-methylaniline and N-methylindole; the product from the bottom of the second distillation tower T2 is further input into the third distillation tower T3, the number of plates in the third distillation tower T3 is 15, the reflux ratio is 10, and the top pressure (absolute pressure) is 0.02MPa to obtain N-methylindole.

[0109] The products in the co-production system were sampled and analyzed, and the results showed that in the first reaction zone R1, the aniline conversion rate was 96%, and in the second reaction zone R2, the N-methylindole yield was 75% (calculated as ethylene glycol).

[0110] Comparative Example 1

[0111] and Figure 2Compared with the system schematic diagram shown in FIG. 1 , in the system for co-producing N-methylaniline and N-methylindole adopted in Comparative Example 1, the reaction device R has only one reaction zone, and the second preheating device E2 and the second mixing device M2 are not provided. Aniline, methanol and ethylene glycol are transported to the reaction mixer M1 by a plunger pump in a molar ratio of 4:8:1, and the liquid air velocity of aniline is maintained at 0.4 h -1 , use a plunger pump to press the water for 0.05 h -1 The air velocity is pumped into the mixer, and then the mixture of the three raw materials and water enters the preheater E1 for gasification. The temperature of the preheater E1 is 200 ° C. The gasified aniline, methanol and water enter the reaction device R, the reaction temperature is 250 ° C, the reaction pressure is 0 MPa, and the gas-solid phase reaction is carried out with the first Cu-based catalyst. The first Cu-based catalyst is the same as that in Example 2 and has undergone the same reduction treatment.

[0112] The product was sampled and analyzed, and the results showed that the aniline conversion rate was 50%, the N-methylaniline yield was 45% (calculated as aniline), the N-methylindole yield was 8% (calculated as ethylene glycol), and the impurity content (N, N-dimethylaniline, indole, dimethylindole) accounted for more than 20%, which was much higher than the impurity proportion in Examples 1 and 2.

[0113] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0114] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0115] The above is a detailed introduction to a method and system for co-producing N-methylaniline and N-methylindole provided by the present invention. Specific examples are used herein to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for co-producing N-methylaniline and N-methylindole, characterized in that: The method comprises: The first Cu-based catalyst catalyzes a first reaction between aniline and methanol to obtain a first gaseous mixed system containing N-methylaniline; Ethylene glycol is introduced into the first gaseous mixed system, and part of the N-methylaniline in the first gaseous mixed system reacts with the ethylene glycol under the catalysis of a second Cu-based catalyst to be converted into N-methylindole, thereby finally obtaining a second gaseous mixed system containing N-methylaniline and N-methylindole; Condensing, flashing and rectifying the second gaseous mixed system to separate the N-methylaniline and the N-methylindole; Wherein, the molar ratio of aniline to methanol is 1:2 to 1:4, and the molar ratio of ethylene glycol to aniline is 1:4 to 1:8; In the first reaction, the reaction temperature is 200-250°C and the reaction pressure is 0-0.5 MPa; In the second reaction, the reaction temperature is 220-270°C and the reaction pressure is 0-0.5 MPa; The first Cu-based catalyst is formed by supporting CuO and a first auxiliary metal on a carrier; wherein the first auxiliary metal is selected from at least one of Ce, La, Zr, Mo, Y, Co and Mg, with a mass ratio of 10-20%; the mass ratio of CuO is 30-45%; the carrier includes copper aluminum spinel, silica, alumina, carbon black or zeolite molecular sieve; The second Cu-based catalyst is formed by CuO and a second auxiliary metal, or CuO, a second auxiliary metal and a third auxiliary metal loaded on a carrier; wherein the carrier is selected from copper aluminum spinel, silica, alumina, carbon black or zeolite molecular sieve; the second auxiliary metal is Zr, and the third auxiliary metal is selected from at least one of Mg, Zn, Ce, Mo, La, Y, Cr, Ni and Co; in the second Cu-based catalyst, the mass proportion of the second auxiliary metal is 1-10%, the mass proportion of the third auxiliary metal is 0-10%, and the mass proportion of CuO is 10-30%.

2. The method for co-producing N-methylaniline and N-methylindole according to claim 1, characterized in that: Before the first Cu-based catalyst catalyzes the first reaction between aniline and methanol, the method further comprises: mixing aniline, methanol and water, preheating and gasifying them, and then catalytically contacting them with the first Cu-based catalyst to perform the first reaction; wherein, The feed space velocity of the aniline is 0.2 to 0.8 h -1 ; The feed space velocity of the water is 0 to 0.2 h -1 .

3. The method for co-producing N-methylaniline and N-methylindole according to claim 1, characterized in that: Before introducing ethylene glycol into the first gaseous mixed system, the method further comprises: mixing ethylene glycol with water, preheating and gasifying the mixture, and then mixing the mixture with the first gaseous mixed system; wherein, The feed space velocity of ethylene glycol is 0.06 to 0.1 h -1 ; The feed space velocity of the water is 0 to 0.15 h -1 .

4. The method for co-producing N-methylaniline and N-methylindole according to claim 1, characterized in that: The condensation, flash evaporation and rectification process comprises: condensing the second gaseous mixed system and collecting the liquid portion to obtain a first crude product; Flash distilling the first crude product to remove impurities, collecting the liquid portion, and obtaining a second crude product; performing a first distillation treatment on the second crude product to separate the light components of the raw materials and leave a mixed product; The mixed product is subjected to a second distillation treatment to separate a mixture of N-methylaniline and N-methylindole; The N-methylindole mixture is subjected to a third distillation treatment to separate the N-methylindole from heavy components.

5. A system for co-producing N-methylaniline and N-methylindole, characterized in that: The system is used to implement the method for co-producing N-methylaniline and N-methylindole according to any one of claims 1 to 4, comprising a reaction device and a separation device connected in sequence, wherein the reaction device comprises a first reaction zone and a second reaction zone; wherein: The first reaction zone is configured to catalyze a first reaction between aniline and methanol using a first Cu-based catalyst to obtain a first gaseous mixed system containing N-methylaniline; The second reaction zone is configured to catalyze a second reaction of a portion of N-methylaniline in the gaseous mixed system with ethylene glycol using a second Cu-based catalyst to convert the portion into N-methylindole, thereby finally obtaining a second gaseous mixed system containing N-methylaniline and N-methylindole; The separation device is configured to perform condensation, flash evaporation and rectification on the second gaseous mixed system to separate the N-methylaniline and the N-methylindole; Wherein, the molar ratio of the aniline to the methanol is 1:2 to 1:4, and the molar ratio of the ethylene glycol to the aniline is 1:4 to 1:

8.

6. The system for co-producing N-methylaniline and N-methylindole according to claim 5, characterized in that: The system further comprises a first preheating device and a second preheating device; wherein, The first preheating device is connected to the first reaction zone, and the first preheating device is configured to heat and gasify aniline, methanol and water, and after obtaining a gaseous fluid, input it into the first reaction zone for a first reaction; The second preheating device is connected to the second reaction zone, and is configured to heat and gasify ethylene glycol and water to obtain a gaseous fluid, which is then input into the second reaction zone to mix with the first gaseous mixed system for a second reaction.

7. The system for co-producing N-methylaniline and N-methylindole according to claim 6, characterized in that: The system further comprises a first mixing device and a second mixing device; wherein, The first mixing device is connected to the first preheating device, and the first mixing device is configured to fully mix aniline, methanol and water, and then input them into the first preheating device for heating and gasification; The second mixing device is communicated with the second preheating device, and the second mixing device is configured to fully mix ethylene glycol and water and then input the mixed mixture into the second preheating device for heating and gasification.

8. The system for co-producing N-methylaniline and N-methylindole according to claim 5, characterized in that: The separation device includes a condenser, a flash tank, a first distillation tower, a second distillation tower and a third distillation tower; wherein, The condenser is connected to the second reaction zone and is used to condense the second gaseous mixed system and collect the bottom liquid portion as the first crude product; The flash tank is connected to the condenser and is used to flash the first crude product to remove impurities and collect the bottom liquid portion as the second crude product; The first distillation tower is connected to the flash tank and is used to perform distillation treatment on the second crude product to separate the light components of the raw materials and leave the remaining mixed products; The second distillation tower is connected to the first distillation tower and is used to perform distillation treatment on the mixed product to separate the N-methylaniline and N-methylindole mixture; The third distillation tower is connected to the second distillation tower and is used to perform distillation treatment on the N-methylindole mixture to separate the N-methylindole from heavy components.

9. The system for co-producing N-methylaniline and N-methylindole according to claim 8, characterized in that: The first distillation tower, the second distillation tower and the third distillation tower are all packed towers, the number of theoretical plates is 10 to 50, the reflux ratio is controlled at 0.5 to 20, and the tower top pressure is 0.01 to 0.1 MPa.

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