Method for preparing piperazine through amination reaction of alcohol amine

Abstract

The invention discloses a method for preparing piperazine through amination reaction of alcohol amine, which comprises the following steps of: contacting and reacting mixed gas containing preheated and vaporized raw materials and ammonia gas with a catalyst to obtain piperazine, the catalyst comprises an active component and an accelerant, and the preparation method of the catalyst comprises the following steps: carrying out alkali treatment and ammonium exchange on a microporous molecular sieve by using an alkaline solution to obtain a hierarchical pore molecular sieve active component, and loading the accelerant on the hierarchical pore molecular sieve active component to obtain a catalyst precursor, and carrying out steam treatment on the obtained catalyst precursor to obtain the ammoniation catalyst. The catalyst prepared by the method is used for alcohol amine ammonification reaction, has the advantages of simple process, easy separation of the catalyst, high raw material conversion rate, high piperazine selectivity and long service life, and is beneficial to green production.

Description

Technical Field

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

[0002] Piperazine (abbreviated as PIP) is also known as hexahydropyrazine, piperazine, dimethylenediamine, p-diazine, and tetramethyldiamine. Piperazine is an important organic chemical intermediate and has a wide range of applications in medicine, surfactants, synthetic rubber, etc. In the medical field: it is mainly used for the production of pipemidic acid, norfloxacin, clozinic acid, and anthelmintics. Derivatives of piperazine such as methylpiperazine, ethylpiperazine, and 2-methylpiperazine are raw materials for the production of drugs such as enoxacin, ofloxacin, and lomefloxacin. In terms of surfactants: derivatives of piperazine can be used as emulsifiers, detergents, and dispersants. In terms of anthelmintics, inorganic salts of piperazine can be used as animal anthelmintics. Adding them to feed can effectively treat parasites in animals; while organic salts of piperazine are mostly used as human anthelmintics. In addition, piperazine itself is an antioxidant and can be used for the preservation of vegetable oils; an aqueous solution of piperazine and ethylene glycol can be used as a corrosion inhibitor; a condensate of piperazine, formaldehyde, and dialkylphenol can be used as a stabilizer for lubricating oils; rubber additives: a piperazine derivative formed by the reaction of piperazine, carbon disulfide, and formaldehyde can be used as a rubber vulcanization accelerator.

[0003] CN109908900A discloses a supported catalyst for preparing ethylenediamine by the ethanolamine method. The main active components of the catalyst are Ni, Co, or Cu, and the promoter is at least one of metals or oxides such as Fe, Cr, Re, Ru, B, Mg, Ba, etc.; the carrier is alumina, silica, alumina-silica, H-ZSM-5, or H-β molecular sieve. Under the condition of hydrogen, the reaction pressure is 5.0 - 12.0 MPa, and ethanolamine and liquid ammonia are used to prepare ethylenediamine and piperazine at 110 - 240 °C, while co-producing diethylenetriamine (DETA), hydroxyethylpiperazine (HEP), N-aminoethylpiperazine (AEP), etc. The conversion rate of ethanolamine can reach 86.3%, the selectivity of ethylenediamine can reach 42.3%, and the selectivity of piperazine can reach 22.1%. CN104628675A discloses a method for synthesizing piperazine and triethylenediamine. Ethanolamine and ammonia are mixed and gasified, and the amination reaction is carried out in the presence of catalyst A with mesoporous-microporous composite molecular sieve MOR / MCM-41 as the carrier and catalyst B with mesoporous-microporous composite molecular sieve ZSM-5 / MCM-41 as the carrier. The conversion rate of ethanolamine can reach 95%, the selectivity of piperazine is 45%, and the selectivity of triethylenediamine is 52%. Summary of the Invention

[0004] The object of the present invention is to provide an amination catalyst and a preparation method thereof. The prepared catalyst is used for the amination reaction of alkanolamine to synthesize piperazine, with a simple process, easy separation of the catalyst, high raw material conversion rate, high selectivity to piperazine, long catalyst life, and being conducive to green production.

[0005] In one aspect of the present application, a method for preparing piperazine by the amination reaction of alkanolamine is provided. The method includes: contacting a mixed gas containing preheated and vaporized raw materials and ammonia with a catalyst for reaction to obtain piperazine.

[0006] The catalyst includes an active component and a promoter; the active component is a hierarchical pore molecular sieve, the hierarchical pore molecular sieve has mesopore I and mesopore II, the promoter includes a promoter element, and the promoter element is selected from at least one of P, K, Zn, and Mg.

[0007] The catalyst preparation method includes:

[0008] a) Treating a microporous molecular sieve with an alkaline solution, followed by drying I and calcination I to obtain substance a;

[0009] b) Performing ammonium exchange on the substance a with an ammonium salt solution, followed by drying II and calcination II to obtain a hierarchical pore molecular sieve active component;

[0010] c) Adding the hierarchical pore molecular sieve active component to a promoter precursor solution for impregnation, followed by drying III and calcination III to obtain substance b;

[0011] d) Performing steam treatment on the substance b to obtain the amination catalyst.

[0012] Optionally, in step a), the microporous molecular sieve includes at least one of ZSM-5 molecular sieve, ZSM-11 molecular sieve, β molecular sieve, or mordenite; the silica-alumina ratio of the microporous molecular sieve is 5 to 100.

[0013] Optionally, the hierarchical pore molecular sieve has mesopore I and mesopore II, the pore diameter of mesopore I is 3 nm to 10 nm, and the pore diameter of mesopore II is 15 nm to 40 nm.

[0014] Optionally, the alkaline solution is an aqueous solution containing an alkaline substance;

[0015] The alkaline substance is selected from at least one of NaOH, LiOH, KOH, CsOH, Na2CO3, and K2CO3.

[0016] Preferably, the microporous molecular sieve is a ZSM-5 molecular sieve, and the alkaline solution is an aqueous NaOH solution.

[0017] Optionally, in step a), in the alkaline solution, the concentration of the alkaline substance is 0.01 - 2 mol / L, the solid-liquid ratio of the microporous molecular sieve to the solution is 1:10 - 50 g / ml, the alkali treatment temperature is 30 - 90 °C, the alkali treatment time is 10 - 60 min, the temperature of drying I is 40 - 120 °C, and the time of drying I is 10 - 30 h.

[0018] Preferably, the concentration of the alkaline solution is 0.05 - 0.3 mol / L, the solid-liquid ratio of the molecular sieve to the solution is 1:25 - 35 g / ml, the alkali treatment temperature is 50 - 85 °C, the alkali treatment time is 25 - 45 min, and the temperature of drying I is 60 - 100 °C;

[0019] Optionally, in the alkaline solution, the lower limit of the concentration of the alkaline 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 alkali can be independently selected from 0.6 mol / L, 1 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L.

[0020] Optionally, during the alkali treatment, 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.

[0021] Optionally, the lower limit of the alkali treatment temperature can be independently selected from 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C; the upper limit of the alkali treatment temperature can be independently selected from 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C.

[0022] Optionally, the lower limit of the alkali treatment time can be independently selected from 10 min, 15 min, 20 min, 25 min, 30 min; the upper limit of the alkali treatment time can be independently selected from 35 min, 40 min, 45 min, 50 min, 60 min.

[0023] Optionally, the temperature of calcination I is 400 - 650 °C, and the time of calcination I is 2 - 5 h.

[0024] Optionally, in step b), the ammonium salt in the ammonium salt solution 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 ammonium exchange temperature is 70 - 95 °C, the ammonium exchange time is 1 - 3 h, the number of ammonium exchange times is 1 - 5 times, the temperature of drying II is 40 - 120 °C, the time of drying II is 10 - 30 h, the temperature of calcination II is 400 - 600 °C, and the time of calcination II is 2 - 5 h;

[0025] Preferably, the concentration of the ammonium salt solution is 0.8 mol / L, the ammonium exchange reaction temperature is 85 °C, the ammonium exchange reaction time is 2 h, the number of ammonium exchange times is 3 times, the temperature of drying II is 100 °C, the time of drying II is 24 h, the temperature of calcination II is 550 °C, and the time of calcination II is 3 h.

[0026] Optionally, the promoter precursor is a soluble salt containing a promoter element, and the promoter element is selected from at least one of P, K, Zn, and Mg. The promoter precursor is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium nitrate, potassium chloride, potassium sulfate, zinc nitrate, zinc chloride, magnesium nitrate, and magnesium chloride.

[0027] Optionally, the content of the promoter precursor in the promoter precursor solution is 0.01 - 10 wt% of the mass of the active component of the hierarchical pore molecular sieve, calculated based on the mass of the promoter element; during the impregnation process, the ratio of the mass of the active component of the hierarchical pore molecular sieve to the volume of the promoter precursor solution is 1:2 - 10 g / ml, and 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.

[0028] Preferably, the mass content of the promoter element in the promoter solution is 0.5 - 5 wt% of the content of the active component of the hierarchical pore molecular sieve; during the impregnation process, the ratio of the mass of the active component of the hierarchical pore molecular sieve to the volume of the impregnation solution is 1:3 - 6, and the impregnation time is 10 - 25 h; the temperature of drying III is 50 - 100 °C, the time of drying III is 20 - 30 h; the temperature of calcination III is 450 - 600 °C, and the time of calcination III is 3 h.

[0029] Optionally, the steam used in the steam treatment is the steam of aqueous methylamine solution or aqueous ethylamine solution;

[0030] The mass content of methylamine in the aqueous methylamine solution is 0% - 50%;

[0031] In the aqueous ethylamine solution, the mass content of ethylamine is 0% - 50%;

[0032] The temperature of the steam treatment is 300-600°C, and the time of the steam treatment is 2-6 h.

[0033] Preferably, the mass content of methylamine or ethylamine in the aqueous solution of methylamine or ethylamine is 10%-40%.

[0034] Optionally, the temperature of the steam treatment is independently selected from any value of 300°C, 400°C, 500°C, 600°C or the range value between two values.

[0035] Optionally, the time of the steam 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.

[0036] Optionally, the raw material is a mixed solution of alkanolamine and solvent, the alkanolamine is at least one of monoethanolamine, diethanolamine, and triethanolamine, the solvent is any one of water and 1,4-dioxane, and the mass content of alkanolamine in the mixed solution is 10%-90%.

[0037] Optionally, the mass hourly space velocity of alkanolamine in the raw material is 0.1-10 h -1 .

[0038] Optionally, the molar ratio of alkanolamine to ammonia in the mixed gas is 1:0.1-10.

[0039] Optionally, the temperature of the reaction is 150-450°C, and the pressure of the reaction is 0.01-1.0 Mpa;

[0040] 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.

[0041] 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.

[0042] Optionally, the reaction is carried out in a fixed bed reactor, and the number of the fixed bed reactors is at least 1.

[0043] The beneficial effects that can be produced by the present invention include:

[0044] (1) The present invention provides a preparation method of an ammoniation catalyst for alkanolamine ammoniation reaction. Through the preparation method of alkali treatment-impregnation-steam treatment, the pore structure of the molecular sieve catalyst is improved, two mesoporous structures with different pore size distributions are introduced into the microporous molecular sieve, the acidity of the molecular sieve is regulated, the conversion rate of ethanolamine and the selectivity of piperazine are greatly improved, and the service life of the catalyst is prolonged.

[0045] (2) In the preparation method of the catalyst of the present invention, ethanolamine is used to controllably obtain highly selective piperazine. The raw materials are rich in source and low in price, the process is simple, and the applied catalyst is inexpensive, which is beneficial to reducing production costs.

[0046] (3) The catalyst prepared by this method is used in the amination reaction of alkanolamine. The process is simple, the catalyst is easy to separate, the raw material conversion rate is high, the selectivity to piperazine is high, and the catalyst has a long service life, which is beneficial to green production. Description of the Drawings

[0047] Figure 1 It is the scanning electron microscope image (Figure a, scale bar is 100 nm) and transmission electron microscope image (Figure b, scale bar is 50 nm) of the sample prepared in Example 4 of the present invention.

[0048] Figure 2 It is the nitrogen adsorption diagram of the sample prepared in Example 5 of the present invention. Figure a is the nitrogen adsorption isotherm, and Figure b is the BJH pore size distribution curve. Detailed Description of the Invention

[0049] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0050] Unless otherwise specified, the raw materials and solvents in the embodiments of the present invention are purchased through commercial channels.

[0051] The analysis methods in the embodiments of the present invention are as follows:

[0052] The present invention uses the ASAP 2020PLUS HD88 type physical adsorption instrument of Micromeritics to perform nitrogen physical adsorption characterization on the hierarchical pore molecular sieve. The analysis conditions are as follows: 0.10 g of molecular sieve is loaded into a quartz adsorption tube, vacuum-treated at 350 °C for 10 h to remove the moisture and impurities adsorbed by the molecular sieve material, and a 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, the t-plot method is used to calculate the micropore specific surface area and micropore volume of the molecular sieve sample, the total pore volume of the sample is obtained by using the volume of adsorbed nitrogen at P / P0 = 0.99, the mesopore specific surface area is calculated by the difference between the obtained total specific surface area and micropore specific surface area, the mesopore volume is calculated by the difference between the obtained total pore volume and micropore volume, and the BJH model is used to calculate the mesopore distribution information of the sample.

[0053] The present invention uses an Agilent 7890B gas chromatograph, an FID detector, and a Pona chromatographic column to analyze the products.

[0054] Example 1 Preparation of Hierarchical Pore Molecular Sieve

[0055] Take 600 ml of an aqueous solution containing 0.1 mol / L of NaOH, heat it in a water bath to 65 °C, add 20.00 g of microporous ZSM-5 molecular sieve (Si / Al = 35), stir at 65 °C for 30 min, then centrifuge and wash until the washing liquid is neutral. Dry the obtained molecular sieve solid at 100 °C for 12 h and calcine it at 550 °C for 3 h to obtain Substance I. Take 280 ml of 0.8 mol / L ammonium nitrate solution, preheat it to 85 °C, add 14.0 g of Substance I, stir and exchange for 2 h, repeat the exchange 3 times, then centrifuge and wash, dry at 100 °C for 12 h, and finally calcine at 550 °C for 3 h. The obtained solid is the said hierarchical pore molecular sieve, denoted as HZ1.

[0056] Preparation of Hierarchical Pore Molecular Sieve in Example 2

[0057] Prepare the hierarchical pore molecular sieve according to the method of Example 1, except that the original molecular sieve used is ZSM-5 molecular sieve (Si / Al = 80) and the base is KOH. The obtained solid is the said hierarchical pore molecular sieve, denoted as HZ2.

[0058] Preparation of Hierarchical Pore Molecular Sieve in Example 3

[0059] Prepare the hierarchical pore molecular sieve according to the method of Example 1, except that the original molecular sieve used is mordenite (Si / Al = 10), the concentration of NaOH is 0.2 mol / L, and the base treatment temperature is 80 °C. The obtained solid is the said hierarchical pore molecular sieve, denoted as HZ3.

[0060] Preparation of Hierarchical Pore Molecular Sieve in Example 4

[0061] Prepare the hierarchical pore molecular sieve according to the method of Example 1, except that the original molecular sieve used is β molecular sieve (Si / Al = 20), the base is LiOH, the concentration of the base solution is 0.5 mol / L, the concentration of the ammonium salt solution is 0.5 mol / L, and the number of exchange times is 2 times. The obtained solid is the said hierarchical pore molecular sieve, denoted as HZ4. See the scanning electron microscope image and transmission electron microscope image in Figure 1 , from Figure 1 it can be seen that the surface of the molecular sieve is relatively rough in the scanning electron microscope image, and it can be seen that the sample has an obvious mesoporous structure in the transmission electron microscope image.

[0062] Preparation of Catalyst in Example 5

[0063] Prepare 25 mL of an aqueous solution of ammonium dihydrogen phosphate containing 0.1 g of phosphorus. The resulting liquid is the promoter solution. Weigh 5.00 g of the hierarchical pore molecular sieve active component HZ1 and add it to the promoter solution. Stir and impregnate at room temperature for 24 h, dry at 60 °C for 24 h, calcine at 500 °C for 3 h, and then treat the calcined sample with the vapor of 20% aqueous methylamine solution at 500 °C for 3 h. The resulting sample is denoted as Cat-1, and the loading amount of P calculated based on the hierarchical pore molecular sieve active component is 2 mass%. From Figure 2 It can be obtained that there are mesopores with two pore sizes in the sample. The pore size of mesopore I is about 7 nm, and the pore size of mesopore II is 30 nm.

[0064] Preparation of the catalyst in Example 6

[0065] Prepare the catalyst according to the method of Example 5, except that the prepared promoter solution is an aqueous solution of potassium nitrate, and the potassium content in the aqueous solution is 0.1 g. The resulting sample is denoted as Cat-2, and the loading amount of K calculated based on the hierarchical pore molecular sieve active component is 2 mass%.

[0066] Preparation of the catalyst in Example 7

[0067] Prepare the catalyst according to the method of Example 5, except that the prepared promoter solution is an aqueous solution of zinc nitrate, the zinc content in the aqueous solution is 0.25 g, and the temperature of the vapor treatment is 600 °C. The resulting sample is denoted as Cat-3, and the loading amount of Zn calculated based on the hierarchical pore molecular sieve active component is 5 mass%.

[0068] Preparation of the catalyst in Example 8

[0069] Prepare the catalyst according to the method of Example 5, except that the hierarchical pore molecular sieve used is HZ2, the time of the vapor treatment is 4 h, and the vapor is the vapor of 30% aqueous ethylamine solution. The resulting sample is denoted as Cat-4, and the loading amount of P calculated based on the hierarchical pore molecular sieve active component is 5 mass%.

[0070] Preparation of the catalyst in Example 9

[0071] Prepare the catalyst according to the method of Example 5, except that the hierarchical pore molecular sieve used is HZ2, the prepared promoter solution is a magnesium nitrate solution, and the magnesium content in the aqueous solution is 0.1 g. The resulting sample is denoted as Cat-5, and the loading amount of Mg calculated based on the hierarchical pore molecular sieve active component is 2 mass%.

[0072] Preparation of the catalyst in Example 10

[0073] The catalyst was prepared according to the method of Example 5, except that the hierarchical pore molecular sieve used was HZ3, the promoter solution prepared was an aqueous potassium sulfate solution, the potassium content in the aqueous solution was 0.1 g, the steam treatment temperature was 400 °C, and the obtained sample was denoted as Cat-6, wherein the loading amount of K calculated based on the active component of the hierarchical pore molecular sieve was 2% by mass.

[0074] Preparation of the catalyst of Example 11

[0075] The catalyst was prepared according to the method of Example 5, except that the promoter solution prepared was an aqueous ammonium phosphate solution, the phosphorus content in the aqueous solution was 0.05 g, and the obtained sample was denoted as Cat-7, wherein the loading amount of P calculated based on the active component of the hierarchical pore molecular sieve was 1% by mass.

[0076] Preparation of the catalyst of Example 12

[0077] The catalyst was prepared according to the method of Example 5, except that the hierarchical pore molecular sieve used was HZ4 and the promoter solution prepared was an aqueous ammonium phosphate solution, and the obtained sample was denoted as Cat-8, wherein the loading amount of P calculated based on the carrier was 2% by mass.

[0078] Preparation of the catalyst of Comparative Example 1

[0079] The catalyst was prepared according to the method of Example 5, except that the steam treatment was not carried out, and the obtained sample was denoted as Comp-1.

[0080] The components of each catalyst are shown in Table 1.

[0081] Table 1

[0082]

[0083] Application of the catalysts of Examples 13 - 21

[0084] 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 a 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, and the feed space velocity of ethanolamine was 1 h -1 , and the molar ratio of ethanolamine to ammonia was 1:2. The reaction products were collected by condensation and analyzed by gas chromatography. The catalysts used in each example and the reaction results are shown in Table 2.

[0085] Table 2

[0086]

[0087]

[0088] As can be seen from Table 2, compared with Comparative Example 1, the catalyst prepared by the present invention through the preparation method of alkali treatment - impregnation - vapor treatment has improved the pore structure of the molecular sieve catalyst, introduced two mesoporous structures with different pore size distributions into the microporous molecular sieve, regulated the acidity of the molecular sieve, greatly improved the conversion rate of ethanolamine and the selectivity of piperazine, and extended the service life of the catalyst.

[0089] 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, making some changes or modifications using the technical content disclosed above is equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for preparing piperazine by the ammoniation reaction of alkanolamine, characterized in that, The method includes: contacting a mixture of preheated and vaporized raw materials and ammonia with a catalyst, and reacting to obtain piperazine; The catalyst includes an active component and a promoter. The active component is a hierarchical pore molecular sieve, the hierarchical pore molecular sieve has mesopore I and mesopore II, the promoter includes a promoter element, and the promoter element is selected from at least one of P, K, Zn, and Mg; The method for preparing the catalyst includes: a) subjecting a microporous molecular sieve to alkali treatment with an alkaline solution, drying I, and calcining I to obtain substance a; b) subjecting the substance a to ammonium exchange with an ammonium salt solution, drying II, and calcining II to obtain a hierarchical pore molecular sieve active component; c) adding the hierarchical pore molecular sieve active component to a promoter precursor solution for impregnation, drying III, and calcining III to obtain substance b; d) subjecting the substance b to steam treatment to obtain the ammoniated catalyst.

2. The method according to claim 1, characterized in that, The microporous molecular sieve includes at least one of ZSM-5 molecular sieve, ZSM-11 molecular sieve, β molecular sieve, or mordenite; The silica-alumina ratio of the microporous molecular sieve is 5 to 100; The hierarchical pore molecular sieve has mesopore I and mesopore II. The pore diameter of mesopore I is 3 nm to 10 nm, and the pore diameter of mesopore II is 15 nm to 40 nm.

3. The method according to claim 1, characterized in that, The alkaline solution is an aqueous solution containing an alkaline substance; The alkaline substance is selected from at least one of NaOH, LiOH, KOH, CsOH, Na2CO3, and K2CO3; Preferably, in the alkaline solution, the concentration of the alkaline substance is 0.01 to 2 mol / L; Preferably, in 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 the alkali treatment is 30 to 90 °C, and the time of the alkali treatment is 10 to 60 min; Preferably, the temperature of the drying I is 40 to 120 °C, and the time of the drying I is 10 to 30 h; Preferably, the temperature of the calcining I is 400 to 650 °C, and the time of the calcining I is 2 to 5 h.

4. The method according to claim 1, characterized in that, The ammonium salt in the ammonium salt solution 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 ammonium exchange times is 1 to 5 times; Preferably, the temperature of the drying II is 40 to 120 °C, and the time of the drying II is 10 to 30 h; Preferably, the temperature of the calcining II is 400 to 600 °C, and the time of the calcining II is 2 to 5 h.

5. The method according to claim 1, characterized in that, The promoter precursor is a soluble salt containing a promoter element, and the promoter element is selected from at least one of P, K, Zn, and Mg; Preferably, the promoter precursor is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium nitrate, potassium chloride, potassium sulfate, zinc nitrate, zinc chloride, magnesium nitrate, and magnesium chloride.

6. The method according to claim 1, characterized in that, The content of the promoter precursor in the promoter precursor solution is 0.01 to 10 wt% of the mass of the active component of the hierarchical pore molecular sieve, and the promoter precursor is calculated based on the mass of the promoter element; Preferably, during the impregnation process, the ratio of the mass of the active component of the hierarchical pore molecular sieve to the volume of the promoter precursor solution is 1:2 to 10 g / ml, and the impregnation time is 2 to 30 h; Preferably, the temperature of the third drying is 40 to 120 °C, and the time of the third drying is 10 to 50 h; Preferably, the temperature of the third calcination is 400 to 650 °C, and the time of the third calcination is 2 to 5 h.

7. The method according to claim 1, characterized in that, The vapor used in 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% to 50%, preferably 10% to 40%; In the aqueous ethylamine solution, the mass content of ethylamine is 0% to 50%, preferably 10% to 40%; The vapor treatment temperature is 300 to 600 °C, and the time of the vapor treatment is 2 to 6 h.

8. The method according to claim 1, wherein The raw material is a mixed solution of an alkanolamine and a solvent, and the alkanolamine is at least one of monoethanolamine, diethanolamine, and triethanolamine; The solvent is at least one of water and 1,4-dioxane; The mass content of the alkanolamine in the mixed solution is 10% to 90%.

9. The method according to claim 1, wherein The mass hourly space velocity of the alkanolamine is 0.1 to 10 h -1 , and the molar ratio of the alkanolamine 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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