Method for selectively catalyzing synthesis of piperazine or co-production of ethylenediamine by using ethanolamine

Abstract

The invention discloses a method for selectively catalyzing synthesis of piperazine or co-production of ethylenediamine by ethanolamine, which comprises the following steps: (1) in a reaction system containing ethanolamine, ammonia gas, hydrogen, a solvent and a catalyst A, the ethanolamine and the ammonia gas react under the action of the catalyst A to obtain a reaction solution; (2) main production of piperazine or co-production of ethanediamine: i. Co-production of ethanediamine and piperazine: the reaction liquid is distilled to separate ethanediamine and piperazine; and (ii) mainly producing piperazine: continuously reacting the reaction liquid under the catalytic action of a catalyst B to generate piperazine. Compared with the prior art, the method has the advantages that the selective preparation of the ethylenediamine and the piperazine can be realized through simple catalyst replacement, the reaction pressure and the energy consumption are obviously reduced, and the reaction activity and the reaction selectivity of preparing the ethylenediamine and the piperazine by taking ethanolamine and ammonia as raw materials in the presence of hydrogen are improved; the reaction process is flexible and changeable, the universality is high, the market demand change can be quickly responded, the product can be flexibly adjusted, and the method has wide industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic applications of ethanolamine, and particularly relates to a method for selectively catalytically synthesizing piperazine or co-producing ethylenediamine from ethanolamine. Background Art

[0002] Ethylenediamine (EDA) is an important fine chemical, which is widely used in the fields of manufacturing pharmaceutical intermediates, chelating agents, surfactants, pesticides, and resin polymers. With the adjustment and transformation of the national economic industrial structure, the demand for EDA has increased rapidly, with an annual growth rate of more than 20%. However, the current domestic production capacity cannot meet the demand, and it is urgent to develop EDA production technology.

[0003] Piperazine (PIP), as an important fine chemical intermediate, its derivatives have a wide range of uses in the pharmaceutical, pesticide, and dye industries. In the pharmaceutical field, piperazine and its derivatives are the key raw materials for synthesizing quinolone antibacterial drugs (such as norfloxacin and ciprofloxacin). With the continuous growth of the clinical demand for such drugs, the market scale of piperazine products shows a significant expansion trend.

[0004] The EDA synthesis process mainly includes the dichloroethane method and the ethanolamine method. Among them, although the dichloroethane method has low raw material costs and a mature process, it is gradually being phased out due to serious equipment corrosion and environmental pollution problems caused by halogens. The ethanolamine method uses ethanolamine (MEA) and ammonia as raw materials, and through a hydroamination reaction in the presence of hydrogen and a catalyst, ethylenediamine is generated. It has become a new preparation direction due to its low equipment investment cost and small pollution.

[0005] CN109908900A discloses a supported catalyst for preparing ethylenediamine by the ethanolamine method. In this method, in a fixed-bed reactor, monoethanolamine and liquid ammonia mainly produce ethylenediamine and piperazine under hydrohydrogenation conditions. The main active components of the catalyst are Ni, Co, and Cu, and the promoters are at least one of Fe, Cr, Re, Ru, B, Mg, Ba, etc. There are strict restrictions on the specific surface area of the carrier. The preparation of the catalyst in this method is relatively complex. Under the reaction conditions of 160 °C and 8.0 MPa, ethylenediamine is the main product, with a selectivity of 32.9 - 54.2%, and the highest selectivity of piperazine is only 30.8%.

[0006] CN101875014A discloses a catalyst for the conversion of monoethanolamine and ammonia to ethylenediamine under hydrogenation conditions. The catalyst comprises a main active component, a promoter and a support. The main active component is metal Ni or Co; the promoter is one or more of metals or metal oxides of Re, Fe, Cu, Ru and B; the support is Al2O3 or SiO2, and the specific surface area and average pore diameter of the support are defined. This catalyst is used in the reaction for preparing ethylenediamine from monoethanolamine and ammonia. The reaction conditions are as follows: reaction temperature is 135 - 155 °C, hydrogen reaction pressure is 6.5 - 8.0 MPa, and the liquid hourly space velocity of monoethanolamine is 0.35 - 0.65 h -1 . In the examples, the conversion rate of MEA is 30 - 50.8%, the selectivity of ethylenediamine is 45 - 73.5%, and the selectivity of piperazine is only 4.5 - 9.8%. It is impossible to have good MEA conversion rate and piperazine selectivity simultaneously.

[0007] CN118253311A discloses a catalyst for the preparation of ethylenediamine and piperazine, its preparation method and application. The catalyst comprises a support and a main active component and a promoter supported on the support. The support is aluminum oxide, the main active component is nickel, and the promoter is a combination of rhenium, tungsten, praseodymium / erbium in an equal weight ratio; the weight of the main active component nickel accounts for 8 - 12% of the total weight of the catalyst, and the total weight of the promoter accounts for 0.2 - 2% of the total weight of the catalyst. In its examples, under the conditions of reaction temperature of 200 °C and reaction pressure of 15 MPa, the selectivity of piperazine is above 45%, and the sum of the selectivities of ethylenediamine and piperazine is above 75%.

[0008] In summary, in the reaction of preparing ethylenediamine and piperazine from ethanolamine in the prior art, ethylenediamine is mainly the main product, and when further improving the selectivity of piperazine, it is impossible to avoid relatively harsh reaction conditions such as high pressure. Summary of the Invention

[0009] In view of the above problems in the prior art, the present invention provides a method for the selective catalytic synthesis of piperazine or co-production of ethylenediamine from ethanolamine. By screening and optimizing the catalyst and flexibly adjusting the reaction path, it is possible to selectively synthesize piperazine or co-produce ethylenediamine under relatively mild reaction conditions, achieving high selectivities of ethylenediamine and piperazine to meet different market demands.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for the selective catalytic synthesis of piperazine or co-production of ethylenediamine from ethanolamine, comprising the following steps:

[0012] (1) In a reaction system containing ethanolamine, ammonia, hydrogen, a solvent and catalyst A, ethanolamine reacts with ammonia under the action of catalyst A to obtain a reaction solution;

[0013] (2) Main production of piperazine or co-production of ethylenediamine:

[0014] ⅰ. Co-production of ethylenediamine and piperazine: The reaction solution is separated by distillation to obtain ethylenediamine and piperazine;

[0015] ⅱ. Main production of piperazine: The reaction solution continues to react to form piperazine under the catalysis of catalyst B;

[0016] Both catalyst A and catalyst B include a silica molecular sieve support and an active component supported on the silica molecular sieve support; the active component is cobalt or a combination of cobalt and nickel;

[0017] The silica molecular sieve support in catalyst A is a microporous molecular sieve, or a combination of a microporous molecular sieve and a mesoporous molecular sieve, and the mass ratio of the microporous molecular sieve to the mesoporous molecular sieve is greater than 0.5;

[0018] The silica molecular sieve support in catalyst B is a mesoporous molecular sieve, or a combination of a microporous molecular sieve and a mesoporous molecular sieve, and the mass ratio of the microporous molecular sieve to the mesoporous molecular sieve is less than 0.5.

[0019] The present invention is further configured such that the microporous molecular sieve is an S-1 molecular sieve, and the mesoporous molecular sieve is an MCM-41 molecular sieve or an SBA-15 molecular sieve.

[0020] The present invention is further configured such that the molar ratio of ammonia to ethanolamine is 1:1 to 10:1; the molar ratio of hydrogen to ethanolamine is 0.1:1 to 4:1.

[0021] The present invention is further configured such that the molar ratio of ammonia to ethanolamine is 1.5:1; the molar ratio of hydrogen to ethanolamine is 1:1 to 3.5:1.

[0022] The present invention is further configured such that the total loading amount of the active component is 10 to 15 wt% of the mass of the catalyst;

[0023] When cobalt and nickel are used as the active component, the mass ratio of cobalt to nickel is 7:3 to 10:1;

[0024] The addition amount of the catalyst is 1 to 25 wt% of the mass of ethanolamine;

[0025] The concentration of ethanolamine is 0.01 to 0.2 g / mL.

[0026] The present invention is further configured such that when co-producing ethylenediamine and piperazine, in step (1), the reaction temperature is 150 to 180 °C, the reaction pressure is 4 to 8 MPa, and the reaction time is 4 to 12 hours.

[0027] The present invention is further configured that when piperazine is mainly produced, in step (1), the reaction temperature is 160 - 180 °C, the reaction pressure is 5 - 6 MPa, and the reaction time is 2 - 8 hours;

[0028] In step ii, the reaction temperature is 160 - 180 °C, the reaction pressure is 5 - 6 MPa, and the reaction time is 2 - 6 hours.

[0029] The present invention is further configured that the solvent is selected from one or more of tetrahydrofuran, dioxane, acetonitrile, acetone, and ethyl acetate; the solvent is preferably tetrahydrofuran.

[0030] The present invention is further configured that in the reaction system of step (1), the initial pressure of ammonia is 0.1 - 0.6 MPa, and the initial pressure of hydrogen is 0.2 - 1.5 MPa;

[0031] After introducing ammonia and hydrogen, nitrogen is continuously introduced to adjust the reaction system to the reaction pressure.

[0032] The present invention is further configured that the preparation process of the catalyst includes the following steps:

[0033] S1. Loading stage: Prepare a metal salt solution according to the loading amount, and load the metal active component onto an appropriate carrier by loading methods such as impregnation method, ammonia evaporation method, hydrothermal method, or coprecipitation method to obtain a sample; among them, the impregnation method is preferably used;

[0034] S2. Drying stage: Transfer the sample of step S1 into an oven for drying, the drying temperature is 100 - 120 °C, and the drying time is 10 - 20 h;

[0035] S3. Calcination stage: Calcinate the dried product of step S2 in a muffle furnace, the calcination temperature is 500 - 600 °C, and the calcination time is 2 - 10 h;

[0036] S4. Reduction stage: Load the powder calcined in step S3 into a quartz boat and place it in a tube furnace, introduce a H2 - Ar mixed gas, and heat it to 350 - 650 °C at a rate of 1 - 10 °C / min for reduction for 2 - 10 h, and cool down after reduction to obtain the catalyst.

[0037] The present invention is further configured that in step S1, the metal salt is nitrate; in step S4, the volume ratio of H2 in the H2 - Ar mixed gas is 5 - 30%, preferably 10%.

[0038] The present invention is further configured that the specific steps of the above loading method are as follows:

[0039] A) Impregnation method: Place the all-silica molecular sieve support in a crucible, drop the metal salt solution into the crucible, stir to form a pasty suspension, and leave the crucible containing the sample open at room temperature for 12 - 24 h to preliminarily evaporate the moisture;

[0040] B) Ammonia evaporation method: Mechanically mix the metal salt solution and the all-silica molecular sieve support in a beaker, drop in ammonia water and stir. After stirring evenly, heat to pH = 7, and then filter;

[0041] Optionally, the concentration of ammonia water is 28 - 30%, the addition amount of ammonia water is 10 - 30 mL, and the stirring time is 4 - 8 h;

[0042] C) Hydrothermal method: Stir and mix the metal salt solution and the all-silica molecular sieve support evenly, place them in a polytetrafluoroethylene liner, put them into a hydrothermal autoclave and place it in an oven for hydrothermal reaction. After the hydrothermal reaction is completed, take it out, cool down and then filter;

[0043] Optionally, the hydrothermal time is 24 - 72 h, and the hydrothermal temperature is 150 - 200 °C.

[0044] Those skilled in the art can select a suitable reactor according to the actual production needs. The reactors include batch kettle reactors, continuous kettle reactors, fixed bed reactors, etc. The present invention preferably uses a batch kettle reactor.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) Compared with the existing technology, the present invention can realize the selective preparation of ethylenediamine and piperazine by simply replacing the catalyst, significantly reducing the reaction pressure and energy consumption, and improving the reaction activity and reaction selectivity for preparing ethylenediamine and piperazine from ethanolamine and ammonia as raw materials under hydrogenation conditions.

[0047] (2) The catalyst used in the present invention has the advantages of simple and easy preparation method, low cost, low equipment requirements, mild required reaction conditions, etc., and has a high ethanolamine conversion rate and selectivities for ethylenediamine and piperazine.

[0048] (3) The method of the present invention can not only achieve a high product yield, but also has a flexible and variable reaction process, strong universality, can quickly respond to changes in market demand, flexibly adjust the products, and has a wide range of industrial applications. Detailed implementation manners

[0049] The technical solutions of the present invention will be clearly and completely described below through specific embodiments. It should be understood that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of the present invention. Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art.

[0050] The materials used in the following examples are all commercially available products. The S-1 molecular sieve, MCM-41 molecular sieve, and SBA-15 molecular sieve used in the following examples are all all-silica molecular sieves.

[0051] Preparation Example 1

[0052] The Co / S-1 catalyst precursor was prepared by the impregnation method. The cobalt source used was cobalt nitrate solution, and Silicalite-1 molecular sieve (S-1 molecular sieve) was used as the carrier; the loading amount of Co was 10 wt%.

[0053] The molecular sieve carrier was placed in a crucible, and the metal salt solution prepared according to the above loading amount was dropped into the crucible, and stirred to form a paste-like suspension. The crucible containing the sample was left standing open at room temperature for 24 h to ensure sufficient contact and preliminary evaporation of water, and then dried overnight in an oven at 110 °C, and finally calcined in a muffle furnace at 550 °C for 6 h to obtain the cobalt-based catalyst precursor.

[0054] The above catalyst precursor was placed in a tubular furnace for reduction activation. The reducing gas was a H2-Ar mixed gas with a H2 volume ratio of 10%. The heating rate was 5 °C / min, and it was kept at 450 °C for 4 h, and then cooled to room temperature to obtain a highly active and highly stable Co / S-1 catalyst.

[0055] Preparation Example 2

[0056] This preparation example is basically the same as Preparation Example 1, except that the loading amount of Co is 15 wt%, and finally a highly active and highly stable Co / S-1 catalyst is obtained.

[0057] Preparation Example 3

[0058] The Co-Ni / S-1 catalyst precursor was prepared by the ammonia evaporation method. The cobalt source used was cobalt nitrate solution, the nickel source used was nickel nitrate solution, and S-1 molecular sieve was used as the carrier; the loading amount of Co was 7 wt%, and the loading amount of Ni was 3 wt%.

[0059] Add 20 mL of ammonia water with a concentration of 28 - 30% to the cobalt nitrate solution. After stirring for 10 min, add S-1 molecular sieve, and continue stirring for 4 h. Heat to pH = 7 at 80 °C, filter, dry overnight in an oven at 110 °C, and finally calcine in a muffle furnace at 550 °C for 6 h to obtain the cobalt-nickel-based catalyst precursor.

[0060] Place the above catalyst precursor in a tubular furnace for reduction activation. The reducing gas is a H2-Ar mixed gas with a H2 volume ratio of 10%. The heating rate is 5 °C / min, hold at 450 °C for 4 h, and then cool to room temperature to obtain the highly active and stable Co-Ni / S-1 catalyst (ammonia evaporation).

[0061] Preparation Example 4

[0062] Prepare the cobalt-nickel-based catalyst precursor by hydrothermal method. The cobalt source used is cobalt nitrate solution, the nickel source used is nickel nitrate solution, and S-1 molecular sieve is used as the carrier; the loading amount of Co is 7 wt%, and the loading amount of Ni is 3 wt%.

[0063] Stir the cobalt nitrate solution and the molecular sieve evenly, then hydrothermally treat in an oven at 175 °C for 24 h, filter, dry overnight in an oven at 110 °C, and finally calcine in a muffle furnace at 550 °C for 6 h to obtain the cobalt-nickel-based catalyst precursor.

[0064] Place the above catalyst precursor in a tubular furnace for reduction activation. The reducing gas is a H2-Ar mixed gas with a H2 volume ratio of 10%. The heating rate is 5 °C / min, hold at 450 °C for 4 h, and then cool to room temperature to obtain the highly active and stable Co-Ni / S-1 catalyst (hydrothermal).

[0065] Preparation Example 5

[0066] Prepare the cobalt-nickel-based catalyst precursor by impregnation method. The cobalt source used is cobalt nitrate solution, the nickel source used is nickel nitrate solution, and S-1 molecular sieve is used as the carrier; the loading amount of Co is 7 wt%, and the loading amount of Ni is 3 wt%.

[0067] Place the molecular sieve carrier in a crucible, drop the metal salt solution prepared according to the above loading amount into the crucible, stir to form a paste-like suspension, and leave the crucible containing the sample open at room temperature for 24 h to ensure sufficient contact and preliminary evaporation of water. Then dry overnight in an oven at 110 °C, and finally calcine in a muffle furnace at 550 °C for 6 h to obtain the cobalt-nickel-based catalyst precursor.

[0068] Place the above catalyst precursor in a tubular furnace for reduction activation. The reducing gas is a H2-Ar mixed gas with a H2 volume ratio of 10%. The heating rate is 5 °C / min, hold at 450 °C for 4 h, and then cool to room temperature to obtain the highly active and stable Co-Ni / S-1 catalyst.

[0069] Preparation Example 6

[0070] This preparation example is basically the same as Preparation Example 5, except that the loading amount of Co is 10 wt%, the loading amount of Ni is 1 wt%, and finally a highly active and highly stable Co-Ni / S-1 catalyst is obtained.

[0071] Preparation Example 7

[0072] This preparation example is basically the same as Preparation Example 5, except that the loading amount of Co is 10 wt%, the loading amount of Ni is 2 wt%, and finally a highly active and highly stable Co-Ni / S-1 catalyst is obtained.

[0073] Preparation Example 8

[0074] This preparation example is basically the same as Preparation Example 5, except that the loading amount of Co is 10 wt%, the loading amount of Ni is 4 wt%, and finally a highly active and highly stable Co-Ni / S-1 catalyst is obtained.

[0075] Preparation Example 9

[0076] This preparation example is basically the same as Preparation Example 5, except that the carrier used is MCM-41 molecular sieve, and finally a highly active and highly stable Co-Ni / MCM-41 catalyst is obtained.

[0077] Preparation Example 10

[0078] This preparation example is basically the same as Preparation Example 5, except that the carrier used is SBA-15 molecular sieve, and finally a highly active and highly stable Co-Ni / SBA-15 catalyst is obtained.

[0079] Preparation Example 11

[0080] This preparation example is basically the same as Preparation Example 6, except that the carrier used is a combination of S-1 molecular sieve and MCM-41 molecular sieve by a mixed grinding method, and the mass ratio of the two is 7:3, and finally a highly active and highly stable Co-Ni / S-1+MCM-41(7:3) catalyst is obtained.

[0081] Preparation Example 12

[0082] This preparation example is basically the same as Preparation Example 6, except that the carrier used is a combination of S-1 molecular sieve and MCM-41 molecular sieve by a mixed grinding method, and the mass ratio of the two is 5:5, and finally a highly active and highly stable Co-Ni / S-1+MCM-41(5:5) catalyst is obtained.

[0083] Preparation Example 13

[0084] This preparation example is basically the same as Preparation Example 6, except that the carrier used is a combination of S-1 molecular sieve and MCM-41 molecular sieve by mixing and grinding, and the mass ratio of the two is 3:7, and finally a highly active and highly stable Co-Ni / S-1+MCM-41(3:7) catalyst is obtained.

[0085] Preparation Example 14

[0086] This preparation example is basically the same as Preparation Example 6, except that the carrier used is MCM-41 molecular sieve, and finally a highly active and highly stable Co-Ni / MCM-41 catalyst is obtained.

[0087] Comparative Example 1

[0088] This preparation example is basically the same as Preparation Example 1, except that the loading amount of Co is 5 wt%, and finally a Co / S-1 catalyst is obtained.

[0089] Comparative Example 2

[0090] This preparation example is basically the same as Preparation Example 1, except that the loading amount of Co is 20 wt%, and finally a Co / S-1 catalyst is obtained.

[0091] Comparative Example 3

[0092] This preparation example is basically the same as Preparation Example 5, except that the loading amount of Co is 10 wt% and the loading amount of Ni is 7 wt%, and finally a Co-Ni / S-1 catalyst is obtained.

[0093] Comparative Example 4

[0094] This preparation example is basically the same as Preparation Example 5, except that the carrier used is ZSM-5(200) molecular sieve, where (200) represents the silica-alumina ratio of the molecular sieve is 200, and finally a Co-Ni / ZSM-5(200) catalyst is obtained.

[0095] Comparative Example 5

[0096] This preparation example is basically the same as Preparation Example 5, except that the carrier used is ZSM-5(54) molecular sieve, where (54) represents the silica-alumina ratio of the molecular sieve is 54, and finally a Co-Ni / ZSM-5(54) catalyst is obtained.

[0097] Respectively take the catalysts (0.2 g) prepared in the above Preparation Examples 1 to 14 and Comparative Examples 1 to 5, ethanolamine (0.01 mol, 0.62 g), and tetrahydrofuran (10 mL, 8.9 g) and add them to a 50 mL micro autoclave equipped with a polytetrafluoroethylene inner liner; seal the autoclave and introduce nitrogen to discharge the air in the autoclave, and then discharge the mixed gas, and the pressure in the system is normal pressure;

[0098] Introduce a certain amount of ammonia into the autoclave to make the system pressure reach 0.6 MPa, and then continue to introduce hydrogen to make the system pressure reach 1.5 MPa (that is, the molar ratio of MEA, NH3, and H2 is 1:1.5:2.3); heat the autoclave to 160 °C; adjust the pressure in the autoclave to 6 MPa with nitrogen, react for 8 h. After the reaction is completed, turn off the heating. After the temperature in the autoclave drops to room temperature, discharge the remaining gas in the autoclave, open the autoclave body to collect the product and analyze it using gas chromatography. The conversion rate of ethanolamine, the selectivity of ethylenediamine, and the selectivity of piperazine are shown in Table 1 below.

[0099] Table 1 Reaction results under different catalysts

[0100]

[0101]

[0102] As can be seen from Table 1 above, the catalysts prepared by the above Preparation Examples 1-14 can make the conversion rate of ethanolamine range from 33.6% to 85%, and the sum of the selectivities of ethylenediamine and piperazine is above 47.9%. Among them, for the catalysts prepared by the impregnation method, the sum of the selectivities of ethylenediamine and piperazine is above 66.9%, the highest selectivity of ethylenediamine can reach 33.7%, and the highest selectivity of piperazine can reach 72.5%.

[0103] It can be seen from Preparation Examples 1-2 and Comparative Examples 1-2 that when the content of the active component is too high, due to the agglomeration of Co particles on the surface or in the pores, on the one hand, it will reduce the active sites and affect the contact between the reactants and the active component, and on the other hand, it may block the pores and hinder the diffusion of the reactants and reaction intermediates, affecting the mass transfer process, resulting in too low a conversion rate of ethanolamine. Therefore, the loading amount of the active component of the catalyst is preferably 10-15 wt%, more preferably 10 wt%.

[0104] It can be seen from Preparation Examples 5-8 and Comparative Example 3 that when the nickel content in the cobalt-nickel bimetallic active component is too high, it will reduce its dispersion, cause agglomeration, and lead to too low selectivities of ethylenediamine and piperazine, generating too many by-products. And an appropriate amount of cobalt helps to enhance the dispersion of nickel on the surface of the carrier, make its distribution more uniform, increase the active sites of the reaction, and promote the dehydrogenation / hydrogenation reaction. Therefore, the cobalt-nickel mass ratio is preferably 7:3-10:1, more preferably 10:1.

[0105] It can be seen from Preparation Example 5 and Comparative Examples 4-5 that when using a non-all-silica molecular sieve carrier, since the aluminum in the molecular sieve itself has strong acidity, it will cause too many by-products to be generated during the reaction and the selectivity is poor.

[0106] As can be seen from Preparation Example 6 and Preparation Examples 11 - 14 in Table 1 above, under the condition that the active components of the catalyst are the same, since mesoporous molecular sieves are more conducive to the diffusion of macromolecules, after gradually replacing the all - silica molecular sieve with mesoporous molecular sieves, the selectivity of ethylenediamine decreases significantly, while the selectivity of piperazine increases significantly. On this basis, the selective production of piperazine or the co - production of ethylenediamine under milder reaction conditions can be considered by using different catalysts in combination.

[0107] Examples 1 - 12, co - production of piperazine and ethylenediamine

[0108] Take 0.2 g of the catalyst prepared in Preparation Example 6 above, ethanolamine (0.01 mol, 0.62 g) and a solvent (10 mL) and add them to a 50 mL micro - autoclave equipped with a polytetrafluoroethylene liner; seal the autoclave and introduce nitrogen to expel the air in the autoclave, and then discharge the mixed gas. The pressure in the system is normal pressure.

[0109] Introduce a certain amount of ammonia into the autoclave, continue to introduce an appropriate amount of hydrogen, then heat the autoclave to the reaction temperature, adjust the pressure in the autoclave with nitrogen, react for a period of time, turn off the heating after the reaction is completed, wait for the temperature in the autoclave to drop to room temperature, discharge the remaining gas in the autoclave, open the autoclave body to collect the product and analyze it using gas chromatography. Since the boiling point of ethylenediamine is lower than that of ethanolamine, piperazine and other by - products, ethylenediamine can be separated by distillation. Under different reaction temperatures, reaction pressures, reaction times, and molar ratios of MEA, NH3 and H2 and solvent types, the conversion rate of ethanolamine, the selectivity of ethylenediamine and the selectivity of piperazine are shown in Table 2 below.

[0110] Table 2 Reaction results of co - production of piperazine and ethylenediamine under different experimental conditions

[0111]

[0112] As can be seen from Table 2 above, under the reaction conditions of 150 - 180 °C and 3 - 7 MPa, the conversion rate of ethanolamine is 24.3 - 97.5%, the selectivity of piperazine is 18.3 - 63.8%, and the selectivity of ethylenediamine is 4.0 - 36.6%. Preferably, under the reaction conditions of Example 2, the conversion rate of ethanolamine is 85.0%, the selectivity of ethylenediamine is 33.7%, the yield of ethylenediamine is 28.6%, the selectivity of piperazine is 46.3%, and the yield is 39.4%.

[0113] Examples 13 - 25, mainly producing piperazine

[0114] Take 0.2 g of the catalyst prepared in Preparation Example 5, 0.01 mol (0.62 g) of ethanolamine, and a solvent (10 mL) and add them to a 50 mL micro autoclave equipped with a PTFE liner. Seal the autoclave and introduce nitrogen to expel the air in the autoclave. Then discharge the mixed gas, and the pressure in the system is normal pressure;

[0115] Introduce a certain amount of ammonia into the autoclave, continue to introduce an appropriate amount of hydrogen, then heat the autoclave to the reaction temperature, adjust the pressure in the autoclave with nitrogen, react for a period of time. After the reaction is completed, turn off the heating. After the temperature in the autoclave drops to room temperature, discharge the remaining gas in the autoclave, and open the autoclave body to collect the reaction solution;

[0116] The obtained reaction solution continues to react at the original temperature and pressure under the catalytic action of the catalyst prepared in Preparation Example 14; at different reaction temperatures, reaction pressures, reaction times, and molar ratios of MEA, NH3, and H2 and solvent types, the conversion rate of ethanolamine, the selectivity of ethylenediamine, and the selectivity of piperazine are shown in Table 3 below. In the following table, the first reaction time and the second reaction time refer to the catalytic reaction times of the catalysts prepared in Preparation Examples 5 and 14, respectively.

[0117] Table 3 Reaction results of main production of piperazine under different experimental conditions

[0118]

[0119] As can be seen from Table 3 above, when mainly producing piperazine by the method of the present invention, under relatively mild reaction conditions (160 - 180 °C, 5 - 6 MPa), by only changing the catalyst, the conversion rate of ethanolamine can reach 90.2%, the selectivity of piperazine is as high as 80.2%, and the yield of piperazine is as high as 72.3%, breaking through the bottleneck of high energy consumption and low selectivity in piperazine synthesis.

[0120] The above has described the present application in detail, aiming to enable those skilled in the art to understand the content of the present application and implement it. The above are only partial embodiments of the present application and cannot be used to limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine using ethanolamine, characterized in that: The following steps are involved: (1) In a reaction system containing ethanolamine, ammonia, hydrogen, a solvent and a catalyst A, ethanolamine and ammonia react under the action of the catalyst A to obtain a reaction liquid; (2) Mainly produce piperazine or co-produce ethylenediamine: ⅰ. Co-production of ethylenediamine and piperazine: The reaction liquid is distilled to separate ethylenediamine and piperazine; ⅱ. Mainly produce piperazine: The reaction liquid continues to react to produce piperazine under the catalytic action of catalyst B; The catalyst A and the catalyst B both include an all-silicon molecular sieve carrier and an active component supported on the all-silicon molecular sieve carrier; the active component is cobalt or a combination of cobalt and nickel; The all-silicon molecular sieve carrier in the catalyst A is a microporous molecular sieve, or a combination of a microporous molecular sieve and a mesoporous molecular sieve, and the mass ratio of the microporous molecular sieve to the mesoporous molecular sieve is greater than 0.5; The all-silicon molecular sieve carrier in the catalyst B is a mesoporous molecular sieve, or a combination of a microporous molecular sieve and a mesoporous molecular sieve, and the mass ratio of the microporous molecular sieve to the mesoporous molecular sieve is less than 0.

5.

2. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine by ethanolamine according to claim 1, characterized in that: The microporous molecular sieve is S-1 molecular sieve; the mesoporous molecular sieve is MCM-41 molecular sieve or SBA-15 molecular sieve.

3. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine by ethanolamine according to claim 1, characterized in that: The molar ratio of ammonia to ethanolamine is 1:1 to 10:1; the molar ratio of hydrogen to ethanolamine is 0.1:1 to 4:

1.

4. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine using ethanolamine according to claim 1 or 3, characterized in that: The molar ratio of ammonia to ethanolamine is 1.5:1; the molar ratio of hydrogen to ethanolamine is 1:1 to 3.5:

1.

5. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine by ethanolamine according to claim 1, characterized in that: The total loading amount of the active components is 10-15 wt% of the catalyst mass; When cobalt and nickel are used as active components, the mass ratio of cobalt and nickel is 7:3 to 10:1; The amount of the catalyst added is 1 to 25 wt% of the mass of ethanolamine; The concentration of the ethanolamine is 0.01-0.2 g / mL.

6. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine by ethanolamine according to claim 1, characterized in that: When ethylenediamine and piperazine are co-produced, in step (1), the reaction temperature is 150-180° C., the reaction pressure is 4-8 MPa, and the reaction time is 4-12 hours.

7. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine by ethanolamine according to claim 1, characterized in that: When piperazine is mainly produced, in step (1), the reaction temperature is 160-180° C., the reaction pressure is 5-6 MPa, and the reaction time is 2-8 hours; In step ii, the reaction temperature is 160-180° C., the reaction pressure is 5-6 MPa, and the reaction time is 2-6 hours.

8. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine using ethanolamine according to claim 1, characterized in that: The solvent is selected from one or more of tetrahydrofuran, dioxane, acetonitrile, acetone and ethyl acetate.

9. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine using ethanolamine according to claim 1, characterized in that: In the reaction system of step (1), the initial pressure of ammonia is 0.1-0.6 MPa, and the initial pressure of hydrogen is 0.2-1.5 MPa; After introducing ammonia and hydrogen, nitrogen was continuously introduced to adjust the reaction system to the reaction pressure.

10. The method for selectively catalyzing the synthesis of piperazine or co-production of ethylenediamine using ethanolamine according to claim 1, characterized in that: The catalyst is loaded with active components by an impregnation method, an ammonia evaporation method, a hydrothermal method or a co-precipitation method, and then is dried, calcined at a high temperature and reduced in sequence to obtain the catalyst.

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