Method for preparing triethylene diamine through ethanolamine ammonification reaction

Abstract

The invention discloses a method for preparing triethylene diamine through amination reaction of ethanolamine, which comprises the following steps: mixing a preheated and vaporized raw material with ammonia gas to form mixed gas, and contacting and reacting the mixed gas with a catalyst to obtain triethylene diamine, the catalyst comprises an active component and an auxiliary agent. The preparation method of the catalyst comprises the following steps: mixing a microporous molecular sieve and a binder, extruding, molding and roasting to obtain a substance a, adding the substance a into an alkaline solution, carrying out alkali treatment under microwave radiation, carrying out ammonium exchange to obtain a substance b, loading an auxiliary agent on the substance b to obtain a substance c, and carrying out steam treatment on the substance c to obtain the catalyst. The catalyst prepared by the method is used for preparing triethylene diamine through ethanolamine ammonification, the process is simple, the catalyst is easy to separate, the raw material conversion rate is high, the selectivity to triethylene diamine is high, the service life of the catalyst is long, and green production is facilitated.

Description

Technical Field

[0001] The present invention relates to a method for preparing triethylenediamine by the ammoniation reaction of ethanolamine, belonging to the field of catalytic synthesis. Background Art

[0002] Triethylenediamine (TEDA), also known as diazabicyclooctane or triethylenediamine, is the most widely used and largest amount of tertiary amine foaming catalyst in the polyurethane industry. Its series of products are widely used in various products such as polyurethane flexible foams, rigid foams, semi-rigid foams, elastomers, and coatings. The reaction systems for producing triethylenediamine are mainly divided into homogeneous systems and heterogeneous systems. The earliest research on homogeneous systems was the dichloromethane production process, which has been eliminated due to serious pollution and great damage to equipment. Later developments include using organic acids as catalysts, and later using ionic liquids as solvents and catalysts. However, the current development mainly focuses on heterogeneous catalytic systems, including single-metal catalysts, multi-metal mixed catalysts, molecular sieve catalysts, and solid acid catalysts, etc. Currently, the raw materials for synthesizing triethylenediamine mainly include ethanolamine, ethylenediamine, diethanolamine, ethylene oxide, piperazine, and piperazine derivatives, etc. Since ethanolamine is rich in source and low in price, there are many related studies.

[0003] CN107163054A discloses a method for synthesizing triethylenediamine. The catalyst used in this method is modified from HZSM-type molecular sieve with alkaline earth metals. The reaction raw materials are at least one of piperazine, piperazine derivatives, straight-chain alkanolamines, and amine compounds. The selectivity of triethylenediamine can reach more than 90%. CN108465485A discloses a catalyst for the cyclization synthesis of triethylenediamine from ethanolamine. Its active component is TS-1 titanium silicate molecular sieve, and the promoter is strontium oxide (SrO). The conversion rate of ethanolamine can reach 58%, and the highest selectivity of triethylenediamine can reach 72.7%. CN103240116A discloses a catalyst and its preparation method for producing piperazine and triethylenediamine. The H-ZSM-5 molecular sieve is sequentially treated with steam, impregnated in a NaOH solution, and calcined at high temperature, and then recycled with a metal nitrate solution to obtain the catalyst. The conversion rate of ethanolamine can reach 100%, and the selectivity of triethylenediamine can reach 92%. Summary of the Invention

[0004] The purpose of the present invention is to provide a catalyst and its preparation method. The prepared catalyst is used for the ammoniation reaction of ethanolamine to synthesize triethylenediamine, with a simple process, easy separation of the catalyst, high raw material conversion rate, high selectivity for triethylenediamine, long catalyst life, and is conducive to green production.

[0005] In one aspect of the present application, a method for preparing triethylenediamine by the ammoniation reaction of ethanolamine is provided. The preheated and vaporized raw materials are mixed with ammonia gas to form a mixed gas, and the mixed gas is contacted with a catalyst and reacted to obtain triethylenediamine; the catalyst includes an active component and an auxiliary agent, and the active component is a hierarchical pore molecular sieve; the hierarchical pore molecular sieve has micropores, mesopores, and macropores; the auxiliary agent includes an auxiliary agent element, and the auxiliary agent element is selected from at least one of Sr and Zr.

[0006] The preparation method of the catalyst includes:

[0007] a) Mix the microporous molecular sieve with a binder, extrude and form it, and obtain substance a after drying I, calcination I, and pulverization;

[0008] b) Add the substance a to an alkaline solution, perform alkali treatment under microwave radiation, wash, dry II, calcine II, and then perform ammonium exchange to obtain substance b;

[0009] c) Add the substance b to an auxiliary agent solution for impregnation, dry III, and calcine III to obtain substance c;

[0010] d) Perform steam treatment on the substance c to obtain the catalyst.

[0011] Optionally, in the step a), the microporous molecular sieve includes at least one of ZSM-5 molecular sieve or β molecular sieve, and the silica-alumina ratio of the microporous molecular sieve is 10 to 500;

[0012] Optionally, the silica-alumina ratio of the microporous molecular sieve is 20 to 300.

[0013] Optionally, the mesopore aperture of the hierarchical pore molecular sieve is 3 nm to 20 nm, and the macropore aperture of the hierarchical pore molecular sieve is 50 nm to 200 nm.

[0014] Optionally, in the step a), the binder is selected from at least one of alumina, silica gel, and clay.

[0015] Optionally, the mass ratio of the microporous molecular sieve to the binder is 1:0.1 to 10.

[0016] Optionally, the lower limit of the mass ratio of the porous molecular sieve to the binder is independently selected from 1:0.1, 1:0.5, 1:1, 1:2, 1:3, and the upper limit is independently selected from 1:10, 1:9, 1:8, 1:7, 1:6, 1:5.

[0017] Optionally, an acidic aqueous solution is added during the process of mixing and extruding the microporous molecular sieve and the binder, and the acid in the acidic aqueous solution includes at least one of nitric acid, hydrochloric acid, and acetic acid.

[0018] Optionally, the temperature of the first drying is 20 to 80 °C, the time of the first drying is 10 - 30 h, the temperature of the first calcination is 400 to 600 °C, and the time of the first calcination is 2 - 5 h.

[0019] Optionally, the temperature of the first drying is independently selected from any value of 20 °C, 40 °C, 60 °C, 80 °C or a range value between two values;

[0020] Optionally, the time of the first drying is independently selected from any value of 10 h, 15 h, 20 h, 25 h, 30 h or a range value between two values.

[0021] Optionally, the temperature of the first calcination is independently selected from any value of 400 °C, 450 °C, 500 °C, 550 °C, 600 °C or a range value between two values;

[0022] Optionally, the time of the first calcination is independently selected from any value of 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 5 h or a range value between two values.

[0023] Optionally, in step b), the basic substance in the basic solution is at least one of NaOH, LiOH, KOH, CsOH, Na2CO3, K2CO3;

[0024] The basic solution further includes a solvent, and the solvent is water.

[0025] Optionally, in step b), the concentration of the basic substance in the basic solution is 0.01 - 2 mol / L, the solid-liquid ratio of the microporous molecular sieve to the basic solution is 1:10 - 50 g / ml, the alkali treatment temperature is 60 - 120 °C, the alkali treatment time is 5 - 90 min, the temperature of the second drying is 40 - 120 °C, the time of the second drying is 10 - 30 h, the temperature of the second calcination is 400 - 650 °C, and the time of the second calcination is 2 - 5 h.

[0026] Preferably, the concentration of the basic substance in the basic solution is 0.05 - 0.3 M, the solid-liquid ratio of the microporous molecular sieve to the basic solution is 1:25 - 35 g / ml, the alkali treatment temperature is 50 - 85 °C, the alkali treatment time is 10 - 45 min, the temperature of the second drying is 60 - 100 °C, and the temperature of the second calcination is 450 - 550 °C.

[0027] Optionally, the lower limit of the concentration of the basic substance can be independently selected from 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L; the upper limit of the concentration of the basic substance can be independently selected from 0.6 mol / L, 1 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L.

[0028] Optionally, the lower limit of the solid-liquid ratio of the microporous molecular sieve to the alkaline solution can be independently selected from 1:10 g / ml, 1:20 g / ml, 1:24 g / ml, 1:26 g / ml, 1:28 g / ml, 1:29 g / ml; the upper limit of the solid-liquid ratio of the microporous molecular sieve to the alkaline solution can be independently selected from 1:30 g / ml, 1:34 g / ml, 1:38 g / ml, 1:40 g / ml, 1:45 g / ml, 1:50 g / ml.

[0029] Optionally, the power of the microwave radiation is 200-1000 W; the temperature of the microwave radiation is 60-120 °C; the time of the microwave radiation is 5-90 min.

[0030] Optionally, in step b), the ammonium exchange is carried out using an ammonium salt solution; the ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride, and ammonium carbonate, the concentration of the ammonium salt solution is 0.5-1.0 mol / L, the temperature of the ammonium exchange is 70-95 °C, the time of the ammonium exchange is 1-3 h, the number of ammonium exchange times is 1-5 times, the ammonium exchange further includes drying IV and calcination IV, the temperature of drying IV is 40-120 °C, the time of drying IV is 10-30 h, the temperature of calcination IV is 400-600 °C, and the time of calcination IV is 2-5 h.

[0031] Optionally, the concentration of the ammonium salt solution is 0.8 mol / L, the temperature of the ammonium exchange reaction is 85 °C, the time of the ammonium exchange reaction is 2 h, the number of ammonium exchange times is 3 times, the temperature of drying IV is 100 °C, the time of drying IV is 24 h, the temperature of calcination IV is 550 °C, and the time of calcination IV is 3 h.

[0032] Optionally, in step c), the solute in the promoter solution is a soluble salt containing a promoter element, and the promoter element is selected from at least one of Sr and Zr; the solvent in the promoter solution is water.

[0033] Optionally, the promoter solution is selected from at least one of strontium nitrate, strontium chloride, strontium perchlorate, strontium bicarbonate, strontium chlorate, strontium bromide, strontium iodide, zirconium nitrate, zirconium chloride, and zirconium sulfate.

[0034] Optionally, in step c), the impregnation method is equal-volume impregnation. In the promoter solution, the mass content of the soluble salt containing the promoter element is 0.01-10 wt% of the content of substance b, and the soluble salt containing the promoter element is calculated based on the mass of the promoter element; the impregnation time is 2-30 h; the temperature of drying III is 40-120 °C, the time of drying III is 10-50 h; the temperature of calcination III is 400-650 °C, and the time of calcination III is 2-5 h.

[0035] Optionally, the mass content of the auxiliary element in the auxiliary agent solution is 0.05-5 wt% of the content of substance b; the impregnation time is 6-25 h; the temperature of the third drying is 60-100 °C, and the time of the third drying is 15-40 h; the temperature of the third calcination is 450-550 °C, and the time of the third calcination is 3 h.

[0036] Optionally, in step d), the vapor used for the vapor treatment is the vapor of an aqueous solution of methylamine or ethylamine. In the aqueous solution of methylamine, the mass content of methylamine is 0%-50%; in the aqueous solution of ethylamine, the mass content of ethylamine is 0%-50%; the vapor treatment temperature is 300-600 °C, and the time of the vapor treatment is 2-6 h.

[0037] Optionally, the mass content of methylamine or ethylamine in the aqueous solution of methylamine or ethylamine is 5%-40%.

[0038] Optionally, the temperature of the vapor treatment is independently selected from any value of 300 °C, 400 °C, 500 °C, 600 °C or the range value between two values.

[0039] Optionally, the time of the vapor treatment is independently selected from any value of 2 h, 3 h, 4 h, 5 h, 6 h or the range value between two values.

[0040] Optionally, the raw material is a mixed solution of ethanolamine and a solvent, the solvent is any one of water and 1,4-dioxane, and the mass content of the alkanolamine in the mixed solution is 10%-90%.

[0041] Optionally, in the raw material, the mass space velocity of ethanolamine is 0.1-10 h -1 。

[0042] Optionally, in the mixed gas, the molar ratio of alkanolamine to ammonia is 1:0.1-10.

[0043] Optionally, the temperature of the reaction is 150-450 °C, and the pressure of the reaction is 0.01-1.0 Mpa.

[0044] Optionally, the temperature of the reaction is independently selected from any value of 150 °C, 250 °C, 350 °C, 450 °C or the range value between two values;

[0045] Optionally, the pressure of the reaction is independently selected from any value of 0.01 Mpa, 0.05 Mpa, 0.1 Mpa, 0.5 Mpa, 1.0 Mpa or the range value between two values.

[0046] Optionally, the reaction is carried out in a fixed-bed reactor, and the number of the fixed-bed reactors is at least one.

[0047] The beneficial effects that can be produced by the present invention include:

[0048] (1) The present invention provides a preparation method of a catalyst for the ammoniation of ethanolamine to prepare triethylenediamine. The catalyst prepared by means of extrusion, microwave alkali treatment, addition of a promoter, and steam treatment has three pore structures of micropores, mesopores, and macropores at the same time, effectively improves the mass transfer problem caused by the pore structure of the catalyst, regulates the acidity and basicity of the molecular sieve catalyst, reduces carbon deposition, greatly improves the conversion rate of ethanolamine and the selectivity of triethylenediamine, significantly prolongs the service life of the catalyst, and is beneficial to green production.

[0049] (2) In the preparation method of the catalyst of the present invention, triethylenediamine is directly synthesized by one-step ammoniation of ethanolamine. The raw materials are rich in source, low in price, the process is simple, and the applied catalyst is low in price, which is beneficial to cost reduction.

[0050] (3) The catalyst is used for the ammoniation of ethanolamine to prepare triethylenediamine. The process is simple, the catalyst is easy to separate, the raw material conversion rate is high, the selectivity for triethylenediamine is high, and the service life of the catalyst is long, which is beneficial to green production. Description of the Drawings

[0051] Figure 1 It is the nitrogen adsorption diagram of the sample prepared in Example 1 of the present invention. Diagram a is the nitrogen adsorption isotherm, and diagram b is the BJH pore size distribution curve.

[0052] Figure 2 It is the NH3-TPD diagram of the sample prepared in Example 1 of the present invention. The original sample refers to ZSM-5 molecular sieve (Si / Al = 45). Detailed Embodiments

[0053] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0054] Unless otherwise specified, the raw materials and solvents in the embodiments of the present invention are all purchased through commercial channels.

[0055] The analysis methods in the embodiments of the present invention are as follows:

[0056] The present invention uses the ASAP 2020PLUS HD88 physical adsorption analyzer of Micromeritics to perform nitrogen physical adsorption characterization on the hierarchical pore molecular sieve. The analysis conditions are as follows: 0.10 g of the molecular sieve is loaded into a quartz adsorption tube and vacuum-treated at 350 °C for 10 h to remove the moisture and impurities adsorbed by the molecular sieve material. The nitrogen adsorption / desorption experiment is carried out at a temperature of 77.4 K. The Brunauer-Emmett-Teller (BET) equation is used to calculate the total specific surface area of the sample, and the t-plot method is used to calculate the micropore specific surface area and micropore volume of the molecular sieve sample. At P / P0 = 0.99, the total pore volume of the sample is obtained using the volume of adsorbed nitrogen. The mesopore specific surface area is calculated by subtracting the micropore specific surface area from the obtained total specific surface area, and the mesopore volume is calculated by subtracting the micropore volume from the obtained total pore volume. The BJH model is used to calculate the mesopore distribution information of the sample. The 2920 chemisorption analyzer of Micromeritics is used to perform NH3 temperature-programmed desorption characterization (NH3-TPD).

[0057] The present invention uses an Agilent 7890B gas chromatograph, an FID detector, and a Pona chromatographic column to analyze the product.

[0058] Preparation of the catalyst in Example 1

[0059] Take 14.00 g of ZSM-5 molecular sieve (Si / Al = 45) and 6.00 g of alumina powder for physical mixing. After mixing evenly, an appropriate amount of 10 wt% nitric acid solution is added. After mixing evenly, it is put into a mold for extrusion molding. The strip is dried at 60 °C and then calcined at 500 °C for 2 h. Then it is crushed to 20-40 mesh. The obtained solid is substance a1. Weigh 10.00 of substance a1 and add it to 300 ml of 0.2 M NaOH solution. It is treated under 800 W microwave radiation at 65 °C for 10 min, centrifuged and washed until neutral, dried at 100 °C for 12 h, and calcined at 550 °C for 3 h. The obtained solid is added to 0.8 mol / L NH4NO3 solution, and the solid-liquid ratio is 1:20 (g / mL). It is stirred at 85 °C for 2 h and repeated 3 times. Then it is centrifuged and washed, dried at 100 °C for 12 h, and finally calcined at 550 °C for 3 h to obtain substance b1. A strontium nitrate solution containing 0.1 g of Sr by mass is prepared and added to 5.00 g of substance b1 for equal-volume impregnation. After impregnation for 10 h, it is dried at 60 °C for 24 h and calcined at 500 °C for 3 h to obtain substance c1. Substance c1 is treated with the vapor of 20% methylamine aqueous solution at 500 °C for 3 h to obtain the catalyst sample, and the obtained sample is denoted as Cat-1, where the Sr loading is 2%. From Figure 1 It can be seen that the mesopore diameter is about 7 nm, and the macropore diameter is about 60 nm. From Figure 2It can be seen that after extrusion - microwave alkali treatment - promoter loading - steam treatment, the acidity of the catalyst is adjusted, and the amounts of weak acid and strong acid are both reduced to a certain extent.

[0060] Preparation of the catalyst of Example 2

[0061] The catalyst was prepared according to the method of Example 1, except that the binder used was SiO2, the basic substance was LiOH, the alkali treatment temperature was 80 °C, the alkali treatment time was 20 min, the promoter solution used was strontium chloride solution containing 0.05 g of Sr element, and the obtained sample was denoted as Cat-2, in which the loading amount of Sr was 1%.

[0062] Preparation of the catalyst of Example 3

[0063] The catalyst was prepared according to the method of Example 1, except that the silicon - aluminum ratio of the ZSM-5 molecular sieve used was 100, the ratio of the molecular sieve to the binder was 9:1, the basic substance was K2CO3, the concentration of the basic substance was 0.6 M, the alkali treatment temperature was 100 °C, the alkali treatment time was 15 min, the promoter solution used was zirconium nitrate solution containing 0.05 g of Zr element, and the obtained sample was denoted as Cat-3, in which the loading amount of Zr was 1%.

[0064] Preparation of the catalyst of Example 4

[0065] The catalyst was prepared according to the method of Example 1, except that the silicon - aluminum ratio of the ZSM-5 molecular sieve used was 100, the ratio of the molecular sieve to the binder was 6:4, the promoter solution used was strontium nitrate solution containing 0.25 g of Sr element, and the steam treatment temperature was 600 °C, and the obtained sample was denoted as Cat-4, in which the loading amount of Sr was 5%.

[0066] Preparation of the catalyst of Example 5

[0067] The catalyst was prepared according to the method of Example 1, except that the molecular sieve used was β molecular sieve with a silicon - aluminum ratio of 20, the steam treatment time was 2 h, and the steam was the steam of 30% aqueous ethylamine solution, and the obtained sample was denoted as Cat-5, in which the loading amount of Sr was 2%.

[0068] Preparation of the catalyst of Example 6

[0069] The catalyst was prepared according to the method of Example 1, except that the molecular sieve used was β molecular sieve with a silicon - aluminum ratio of 50, the alkali treatment time was 20 min, and the obtained sample was denoted as Cat-6, in which the loading amount of Sr was 2%.

[0070] Preparation of the catalyst of Example 7

[0071] The catalyst was prepared by the method of Example 1, except that the silica-alumina ratio of the ZSM-5 molecular sieve used was 300, the basic substance was KOH, the promoter solution used was a zirconium chloride solution containing 0.1 g of Zr element, the vapor was the vapor of 10% aqueous ethylamine solution, the temperature of the vapor treatment was 400 °C, the time of the vapor treatment was 4 h, and the obtained sample was denoted as Cat-7, in which the loading amount of Zr was 2%.

[0072] Preparation of the catalyst of Example 8

[0073] The catalyst was prepared by the method of Example 1, except that the silica-alumina ratio of the ZSM-5 molecular sieve used was 300, the binder was SiO2, the promoter solution used was a zirconium nitrate solution containing 0.25 g of Zr element, and the obtained sample was denoted as Cat-8, in which the loading amount of Zr was 5%.

[0074] Preparation of the catalyst of Comparative Example 1

[0075] The catalyst was prepared by the method of Example 1, except that the vapor treatment was not carried out, and the obtained sample was denoted as Comp-1, in which the loading amount of Sr was 2%.

[0076] The components and main treatment conditions of each catalyst are shown in Table 1.

[0077] Table 1

[0078]

[0079]

[0080] Application of the catalysts of Examples 9 - 17

[0081] The catalytic reaction performance of the catalyst obtained in the present invention was evaluated using a fixed-bed reactor. 1.00 g of the catalyst was loaded, and 50 wt% aqueous ethanolamine solution was used as the raw material for evaluation. First, the aqueous ethanolamine solution and ammonia gas were introduced into a preheater and preheated and vaporized at 200 °C, and then the vaporized mixture was introduced into the reactor for reaction. The evaluation conditions were 350 °C, 0.1 MPa, the feed space velocity of ethanolamine was 1 h -1 , and the molar ratio of ethanolamine to ammonia gas was 1:2. The reaction products were collected by condensation and analyzed by gas chromatography. The catalysts used and the reaction results in each example are shown in Table 2.

[0082] Table 2

[0083]

[0084] As can be seen from Table 2, compared with Comparative Example 1, the catalyst prepared by the present invention, through the means of extrusion, microwave alkali treatment, addition of additives and steam treatment, simultaneously constructs three pore structures of micropores, mesopores and macropores in the catalyst (mesopores and macropores are shown in Figure 1 ), effectively improves the mass transfer problem caused by the pore structure of the catalyst, regulates the acidity and basicity of the molecular sieve catalyst (as shown in Figure 2 ), reduces carbon deposition, greatly improves the conversion rate of ethanolamine and the selectivity of triethylenediamine, and significantly extends the service life of the catalyst.

[0085] The above are only several embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for preparing triethylenediamine by the ammoniation reaction of ethanolamine, characterized in that, The preheated and vaporized raw materials are mixed with ammonia to form a mixed gas, and the mixed gas contacts with a catalyst and reacts to obtain triethylenediamine; The catalyst includes an active component and a promoter, and the active component is a hierarchical pore molecular sieve; the hierarchical pore molecular sieve has micropores, mesopores, and macropores; The promoter includes promoter elements, and the promoter elements are selected from at least one of Sr and Zr; The method for preparing the catalyst includes: a) Mixing a microporous molecular sieve with a binder, extruding and forming, drying I, calcining I, and pulverizing to obtain substance a; b) Adding the substance a into an alkaline solution, performing alkali treatment under microwave radiation, washing, drying II, calcining II, and then performing ammonium exchange to obtain substance b; c) Adding the substance b into a promoter solution for impregnation, drying III, and calcining III to obtain substance c; d) Performing steam treatment on the substance c to obtain the catalyst.

2. The method according to claim 1, characterized in that, The microporous molecular sieve includes at least one of ZSM-5 molecular sieve or β molecular sieve; the silica-alumina ratio of the microporous molecular sieve is 10 to 500; The mesopore aperture of the hierarchical pore molecular sieve is 3 nm to 20 nm, and the macropore aperture of the hierarchical pore molecular sieve is 50 nm to 200 nm.

3. The method according to claim 1, characterized in that, In step a), the binder is selected from at least one of alumina, silica gel, and clay; Preferably, the mass ratio of the microporous molecular sieve to the binder is 1:0.1 to 10; Preferably, an acidic aqueous solution is added during the process of mixing and extruding the microporous molecular sieve and the binder, and the acid in the acidic aqueous solution includes at least one of nitric acid, hydrochloric acid, and acetic acid; Preferably, the temperature of drying I is 20 to 80 °C, and the time of drying I is 10 to 30 h; The temperature of calcining I is 400 to 600 °C, and the time of calcining I is 2 to 5 h.

4. The method according to claim 1, characterized in that, In step b), the alkaline substance in the alkaline solution is at least one of NaOH, LiOH, KOH, CsOH, Na2CO3, and K2CO3; The alkaline solution further includes a solvent, and the solvent is water; Preferably, the concentration of the alkaline substance in the alkaline solution is 0.01 to 2 mol / L; Preferably, during the alkali treatment process, the solid-liquid ratio of the microporous molecular sieve to the alkaline solution is 1:10 to 50 g / ml; Preferably, the temperature of drying II is 40 to 120 °C, and the time of drying II is 10 to 30 h; Preferably, the temperature of calcining II is 400 to 650 °C, and the time of calcining II is 2 to 5 h; Preferably, the power of the microwave radiation is 200 to 1000 W; the temperature of the microwave radiation is 60 to 120 °C; the time of the microwave radiation is 5 to 90 min.

5. The method according to claim 1, characterized in that, In step b), the ammonium exchange is carried out using an ammonium salt solution; The ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride, and ammonium carbonate; Preferably, the concentration of the ammonium salt solution is 0.5 to 1.0 mol / L; Preferably, the temperature of the ammonium exchange is 70 to 95 °C, the time of the ammonium exchange is 1 to 3 h, and the number of times of the ammonium exchange is 1 to 5 times; Preferably, the ammonium exchange further includes drying IV and calcination IV. The temperature of drying IV is 40-120 °C, the time of drying IV is 10-30 h, the temperature of calcination IV is 400-600 °C, and the time of calcination IV is 2-5 h.

6. The method according to claim 1, characterized in that, The solute in the auxiliary agent solution is a soluble salt containing an auxiliary agent element, and the auxiliary agent element is selected from at least one of Sr and Zr; Preferably, the soluble salt containing an auxiliary agent element is selected from at least one of strontium nitrate, strontium chloride, strontium perchlorate, strontium bicarbonate, strontium chlorate, strontium bromide, strontium iodide, zirconium nitrate, zirconium chloride, and zirconium sulfate.

7. The method according to claim 1, characterized in that, The impregnation is equal-volume impregnation; In the auxiliary agent solution, the content of the soluble salt containing an auxiliary agent element is 0.01-10 wt% of the content of substance b, and the soluble salt containing an auxiliary agent element is calculated based on the mass of the auxiliary agent element; Preferably, the impregnation time is 2-30 h; Preferably, the temperature of drying III is 40-120 °C, and the time of drying III is 10-50 h; Preferably, the temperature of calcination III is 400-650 °C, and the time of calcination III is 2-5 h.

8. The method according to claim 1, wherein The vapor used for the vapor treatment is the vapor of an aqueous methylamine solution or an aqueous ethylamine solution; In the aqueous methylamine solution, the mass content of methylamine is 0%-50%; In the aqueous ethylamine solution, the mass content of ethylamine is 0%-50%; The vapor treatment temperature is 300-600 °C, and the time of the vapor treatment is 2-6 h.

9. The method according to claim 1, wherein The raw material is a mixed solution of ethanolamine and a solvent. The solvent is any one of water and 1,4-dioxane. In the mixed solution, the mass content of ethanolamine is 10%-90%; Preferably, the mass hourly space velocity of the ethanolamine is 0.1 to 10 h -1 , the molar ratio of ethanolamine to ammonia is 1:0.1 to 10; the reaction temperature is 150 to 450 °C, and the reaction pressure is 0.01 to 1.0 MPa.

10. The method according to claim 1, wherein The reaction is carried out in a fixed-bed reactor, and at least one fixed-bed reactor is included.

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