Method for preparing ethylenediamine and piperazine from ethylene glycol

Abstract

The invention discloses a method for preparing ethylenediamine and piperazine from ethylene glycol, which comprises the following steps: in a system containing ethylene glycol, ammonia gas, hydrogen, a solvent and a catalyst, carrying out dehydrogenation, amination and hydrogenation on ethylene glycol and ammonia gas under the action of the catalyst to generate ethanolamine; the ethanolamine is further aminated to generate ethidene diamine; and further reacting ethylene glycol, ethanolamine and ethylenediamine to generate piperazine. According to the present invention, the solubility of ethanolamine and ethylenediamine is increased by introducing the solvent with the high polarity into the reaction system, such that the high ethylene glycol conversion rate is achieved under the mild reaction conditions (180-220 DEG C, 4-5 MPa), and the selectivity of ethylenediamine and piperazine is significantly improved. Wherein the selectivity of ethylene glycol can reach 74.1%, the sum of the selectivity of ethanediamine and piperazine can reach 85.5%, and the selectivity of piperazine can reach 73.3%.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and specifically relates to a method for preparing ethylenediamine and piperazine from ethylene glycol. Background Art

[0002] Ethylenediamine (EDA) is an important organic intermediate for the preparation of a variety of chemicals due to its two active amino groups in its structure. It has a wide range of uses, including broad-spectrum fungicides, chelating agents, epoxy curing agents, hot melt adhesives, corrosion inhibitors and lubricant additives. Piperazine (PZ) is an important organic chemical intermediate due to its unique six-membered ring structure and stable chemical properties. It is widely used in the fields of medicine, pesticides, dyes and surfactants. For example, piperazine can be used as an intermediate for the synthesis of drugs such as lomefloxacin hydrochloride and sparfloxacin.

[0003] At present, the industrial methods for preparing ethylenediamine and piperazine mainly include ethanolamine ammonolysis and ethylene glycol ammonolysis. Among them, ethylene glycol ammonolysis has attracted much attention due to its wide source of raw materials, low price and environmental friendliness. The reaction mechanism of ethylene glycol ammonolysis is: ethylene glycol (EG) and ammonia, under the action of a catalyst, gradually react to generate ethanolamine (MEA), ethylenediamine and piperazine and other by-products.

[0004] In order to achieve the selective amination of ethylene glycol, researchers have made a lot of attempts, but there are still defects such as low selectivity of ethylenediamine and piperazine and harsh reaction conditions.

[0005] CN103664649A discloses a method for preparing monoethanolamine from ethylene glycol, wherein the reaction system consists of ethylene glycol, liquid ammonia and hydrogen, ethylenediamine and liquid ammonia are converted into monoethanolamine under the action of a catalyst, and ethylenediamine and piperazine are co-produced, and under the reaction conditions of 3-18 MPa and 200-350° C., the ethylene glycol conversion rate is 75%, the maximum monoethanolamine yield is 53%, and the selectivity of monoethanolamine is 70.6%. This method has the disadvantages of harsh reaction conditions, high catalyst cost, and low selectivity of ethylenediamine and piperazine.

[0006] US20090030237A1 provides a cobalt-ruthenium catalyst supported by alumina to catalyze the reaction of ethylene glycol and ammonia. Under the reaction conditions of 200 bar and 150-170° C., the ethylene glycol conversion rate is up to 42.6%, the ethylenediamine selectivity is 49.5%, and the ethanolamine selectivity is 29.0%. This method has the problem of too high reaction pressure. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing ethylenediamine and piperazine from ethylene glycol in view of the deficiencies in the prior art. The method has mild reaction conditions and low cost, and can achieve a higher ethylene glycol conversion rate, higher piperazine selectivity and ethylenediamine selectivity, thereby realizing the selective amination of ethylene glycol.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing ethylenediamine and piperazine from ethylene glycol comprises the following steps: in a system containing ethylene glycol, ammonia, hydrogen, a solvent and a catalyst, ethylene glycol and ammonia are dehydrogenated, aminated and hydrogenated under the action of a catalyst to generate ethanolamine; ethanolamine is further aminated to generate ethylenediamine; ethylene glycol, ethanolamine and ethylenediamine are further reacted to generate piperazine.

[0010] In a system of ethylene glycol, ammonia, hydrogen, solvent and catalyst, ethylene glycol is first synthesized into ethanolamine by reductive amination, which involves a hydrogen transfer mechanism and includes three main steps: hydroxyl dehydrogenation, carbonyl imidization and imine hydrogenation. Specifically, ethylene glycol is first dehydrogenated to form aldehyde or ketone, then subjected to nucleophilic attack by NH3 and dehydrated to form imine, and finally the imine is reduced to ethanolamine by catalytic hydrogenation.

[0011] Ethanolamine is further aminated to generate ethylenediamine; the addition of polar solvent increases the solubility of ethanolamine and ethylenediamine, and ethylene glycol, ethanolamine and ethylenediamine further react to generate piperazine.

[0012] The present invention is further configured such that the solvent comprises one or more of tetrahydrofuran, dioxane, acetonitrile, acetone and ethyl acetate.

[0013] The present invention is further configured such that, in the system, the reaction temperature is 180-220° C., the reaction pressure is 4-5 MPa, and the reaction time is 2-16 hours.

[0014] The present invention is further configured that, in the system, the molar ratio of ethylene glycol, ammonia and hydrogen is 1:(0.1-3):

[0015] (0.1-4); the concentration of ethylene glycol is 0.01-0.2 g / mL; the amount of the catalyst added is 1-10% of the mass of ethylene glycol.

[0016] The present invention is further configured that, in the system, the molar ratio of ethylene glycol, ammonia and hydrogen is 1:(0.5-3):

[0017] (0.5-2.3); preferably, the molar ratio of ethylene glycol, ammonia and hydrogen is 1:3:2.3.

[0018] The present invention is further configured such that, in the system, the initial pressure value of ammonia is 0.1-0.6 MPa, and the initial pressure value of hydrogen is 0.2-1.5 MPa.

[0019] The present invention is further configured such that the catalyst comprises a catalyst carrier and an active component loaded on the catalyst carrier, the total loading amount of the active component is 0.1-30% of the catalyst mass, preferably 5-25%, more preferably 10%, and the total loading amount of the active component is calculated as a single metal.

[0020] The present invention is further configured such that the active component is selected from one or more of Ru, Ni, Co, Pt, Mn, Zn, Fe, Cu and Pd.

[0021] The present invention is further configured such that the catalyst carrier is selected from one or more of aluminum hydroxide, zirconium oxide, niobium oxide and S-1 molecular sieve.

[0022] The present invention is further configured that the catalyst is prepared by an equal volume impregnation method, which specifically comprises the following steps:

[0023] (1) Loading stage: Mix an appropriate amount of carrier with metal salt solution and stir to form a paste-like suspension;

[0024] (2) Drying stage: The suspension is left at room temperature for 12-24 hours to evaporate the water, and then dried at 100-120°C for 10-20 hours;

[0025] (3) Calcination stage: calcining the dried product at 500-600°C for 5-10 h to obtain a black powder;

[0026] (4) Reduction stage: The black powder is heated to 350-650°C at a rate of 1-10°C / min under a reducing atmosphere for reduction for 2-10 hours, and then cooled to obtain a gray encapsulated catalyst.

[0027] The present invention is further configured such that the metal salt in the loading stage of step (1) is a nitrate or a chloride;

[0028] In the reduction stage of step (4), the reducing atmosphere used is a H2-Ar mixed gas with a H2 volume ratio of 5-30%, more preferably a H2-Ar mixed gas with a H2 volume ratio of 10%.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention increases the solubility of ethanolamine and ethylenediamine by introducing a highly polar solvent into the reaction system, thereby achieving a higher ethylene glycol conversion rate under milder reaction conditions (180-220° C., 4-5 MPa), and significantly improving the selectivity of ethylenediamine and piperazine. The selectivity of ethylene glycol can reach 74.1%, the sum of the selectivity of ethylenediamine and piperazine can reach 85.5%, and the selectivity of piperazine can reach 73.3%. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in combination with the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0032] In the following examples, if no specific conditions are specified, all experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents and instruments used were those whose manufacturers were specified and were all conventional products that can be purchased commercially.

[0033] Example 1

[0034] (1) Preparation of 10wt% Co / Al(OH)3 Catalyst

[0035] The active component of the catalyst is Co, and cobalt nitrate solution is used as the cobalt source, Al(OH)3 is used as the carrier, and the metal loading amount is based on the total amount of the catalyst and is calculated as a single metal.

[0036] 1) Loading stage: Al(OH)3 is placed in a crucible, and a cobalt nitrate solution prepared according to the loading amount is added dropwise into the crucible, and stirred to form a paste-like suspension;

[0037] 2) Drying stage: The crucible containing the suspension was left open at room temperature for 24 h to ensure adequate contact and initial evaporation of water, and then dried in an oven at 110°C overnight;

[0038] 3) Calcination stage: The dried product is finally loaded into a muffle furnace and calcined at 550°C for 6 hours to obtain a black powder, i.e., a cobalt-based catalyst precursor;

[0039] 4) Reduction stage: The calcined black powder was loaded into a quartz boat and placed in a tubular furnace. A H2-Ar mixed gas was introduced and the temperature was raised to 550°C at a rate of 5°C / min for reduction for 4 hours. After reduction, the temperature was lowered to obtain a gray encapsulated catalyst, that is, a highly active and stable 10wt% Co / Al(OH)3 catalyst.

[0040] (2) The prepared 10wt% Co / Al(OH)3 (0.2g), ethylene glycol (0.01mol, 0.62g), and tetrahydrofuran (10ml, 8.9g) were added to a 50mL micro autoclave equipped with a polytetrafluoroethylene liner; the autoclave was sealed and nitrogen was introduced to exhaust the air in the autoclave, and then the mixed gas was exhausted, and the pressure in the system was normal pressure; a certain amount of ammonia was introduced into the autoclave to make the system pressure reach 0.1MPa, and hydrogen was continued to be introduced to make the system pressure reach 1.0MPa, and the molar ratio of EG, NH3 and H2 was 1:0.5:2.3; the autoclave was heated to 200℃, and the pressure in the autoclave was adjusted to 5MPa with nitrogen, and the reaction was carried out for 10h; after the reaction was completed, the heating was turned off, and after the temperature in the autoclave dropped to room temperature, the remaining gas in the autoclave was exhausted, and the autoclave was opened to collect the product. The gas chromatography analysis results of the product are shown in Table 1.

[0041] Example 2

[0042] This embodiment is basically the same as embodiment 1, except that after the mixed gas is discharged, a certain amount of ammonia is introduced into the autoclave to make the system pressure reach 0.2 MPa, and hydrogen is continued to be introduced to make the system pressure reach 1.1 MPa, and the molar ratio of EG, NH3 and H2 is 1:1:2.3; the gas chromatography analysis results of the product are shown in Table 1.

[0043] Example 3

[0044] This embodiment is basically the same as embodiment 1, except that after the mixed gas is discharged, a certain amount of ammonia is introduced into the autoclave to make the system pressure reach 0.3 MPa, and hydrogen is continued to be introduced to make the system pressure reach 1.2 MPa, and the molar ratio of EG, NH3 and H2 is 1:1.5:2.3; the gas chromatography analysis results of the product are shown in Table 1.

[0045] Example 4

[0046] This embodiment is basically the same as embodiment 1, except that after the mixed gas is discharged, a certain amount of ammonia is introduced into the autoclave to make the system pressure reach 0.6 MPa, and hydrogen is continued to be introduced to make the system pressure reach 1.5 MPa, and the molar ratio of EG, NH3 and H2 is 1:3:2.3; the gas chromatography analysis results of the product are shown in Table 1.

[0047] Example 5

[0048] This embodiment is basically the same as embodiment 1, except that after the mixed gas is discharged, a certain amount of ammonia is introduced into the autoclave to make the system pressure reach 0.6 MPa, and hydrogen is continued to be introduced to make the system pressure reach 0.8 MPa, and the molar ratio of EG, NH3 and H2 is 1:3:0.5; the gas chromatography analysis results of the product are shown in Table 1.

[0049] Example 6

[0050] This example is basically the same as Example 4, except that the pressure in the autoclave is adjusted to 4 MPa with nitrogen and the reaction is carried out for 10 hours. The gas chromatography analysis results of the product are shown in Table 1.

[0051] Example 7

[0052] This embodiment is basically the same as embodiment 4, except that the temperature of the autoclave is raised to 180° C. and the reaction is carried out for 6 hours. The gas chromatography analysis results of the product are shown in Table 1.

[0053] Example 8

[0054] This embodiment is basically the same as embodiment 4, except that the temperature of the autoclave is raised to 220° C. and the reaction is carried out for 14 hours. The gas chromatography analysis results of the product are shown in Table 1.

[0055] Example 9

[0056] This embodiment is basically the same as embodiment 4, except that the temperature of the autoclave is raised to 140° C. and the reaction is carried out for 14 hours. The gas chromatography analysis results of the product are shown in Table 1.

[0057] Example 10

[0058] This embodiment is basically the same as embodiment 4, except that the temperature of the autoclave is raised to 250° C. and the reaction is carried out for 14 hours. The gas chromatography analysis results of the product are shown in Table 1.

[0059] Table 1. Reaction conditions of Examples 2-9 and Comparative Examples 1-2 and gas chromatography analysis results of products

[0060]

[0061] From the results in Table 1, it can be seen that in the present invention, the molar ratio of EG, NH3 and H2 is preferably 1:3:2.3. At this ratio, the sum of the yields of ethylenediamine and piperazine is the highest.

[0062] From the results of Examples 4 and 7-10, it can be seen that the reaction temperature of the present invention is preferably 180-220°C. If the reaction temperature is too low, the conversion rate of ethylene glycol and the selectivity of ethylenediamine and piperazine are all low; if the reaction temperature is too high, although a higher conversion rate can be achieved, more by-products will be generated and difficult to separate.

[0063] Examples 11-20

[0064] This embodiment is basically the same as embodiment 4, except that the composition of the catalyst; the composition of the catalyst and the gas chromatography analysis results of the product are shown in Table 2:

[0065] Table 2. Composition of the catalysts of Examples 11-20 and gas chromatography analysis results of the products

[0066]

[0067] Wherein, in the catalyst of Example 14, m(Al(OH)3):m(Nb2O5)=1:1;

[0068] In the catalyst of Example 15, the loading amount of Ru is 0.1%, the molar ratio of Ru to Co is 1:100, and m(Al(OH)3):m(S-1)=1:1;

[0069] In the catalyst of Example 16, the loading amount of Pt is 0.1%, and the molar ratio of Co, Ni, and Pt is 50:50:1;

[0070] In the catalyst of Example 17, the loading amount of Pt is 0.1%, the molar ratio of Pt to Co is 1:100, and m(Al(OH)3):m(S-1)=1:1;

[0071] In the catalyst of Example 18, the loading amount of Pt is 0.1%, and the molar ratio of Pt to Co is 1:100.

[0072] It can be seen from the results in Table 2 that the active component loading of the catalyst of the present invention is preferably 10%. Further increasing the loading will increase the cost while improving the catalytic effect slightly.

[0073] Embodiment 21

[0074] This example is basically the same as Example 18, except that the solvent used is dioxane (10 ml, 10.33 g); the gas chromatography analysis results of the product are shown in Table 3.

[0075] Embodiment 22

[0076] This example is basically the same as Example 18, except that the solvent used is acetonitrile (10 ml, 7.86 g); the gas chromatography analysis results of the product are shown in Table 3.

[0077] Embodiment 23

[0078] This example is basically the same as Example 18, except that the solvent used is acetone (10 ml, 7.90 g); the gas chromatography analysis results of the product are shown in Table 3.

[0079] Embodiment 24

[0080] This example is basically the same as Example 18, except that the solvent used is ethyl acetate (10 ml, 9.02 g); the gas chromatography analysis results of the product are shown in Table 3.

[0081] Comparative Example 1

[0082] This example is basically the same as Example 18, except that the solvent used is toluene (10 ml, 8.72 g); the gas chromatography analysis results of the product are shown in Table 3.

[0083] Comparative Example 2

[0084] This embodiment is basically the same as Embodiment 18, except that the solvent used is p-xylene (10 ml, 8.61 g); the gas chromatography analysis results of the product are shown in Table 3.

[0085] Table 3 Gas chromatography analysis results of the solvents and products used in Examples 21-25 and Comparative Examples 1-2

[0086]

[0087] From the results in Table 3, it can be seen that adding highly polar solvents such as acetonitrile, acetone and dioxane to the reaction system can achieve a higher ethylene glycol conversion rate and significantly improve the selectivity of ethylenediamine and piperazine, while adding weakly polar solvents such as toluene and p-xylene will greatly reduce the conversion rate of ethylene glycol and the selectivity of ethylenediamine and piperazine.

[0088] The above is a detailed description of the technical solution of the present application. Its purpose is to enable technical personnel familiar with the field to understand the content of the present application and implement it. It cannot be used to limit the scope of protection of the present application. All equivalent changes or modifications made according to the spirit of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing ethylenediamine and piperazine from ethylene glycol, characterized in that: The following steps are involved: In a system containing ethylene glycol, ammonia, hydrogen, a solvent and a catalyst, ethylene glycol and ammonia are dehydrogenated, aminated and hydrogenated in the presence of a catalyst to generate ethanolamine; ethanolamine is further aminated to generate ethylenediamine; ethylene glycol, ethanolamine and ethylenediamine further react to generate piperazine.

2. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 1, characterized in that: The solvent includes one or more of tetrahydrofuran, dioxane, acetonitrile, acetone and ethyl acetate.

3. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 1, characterized in that: In the system, the reaction temperature is 180-220° C., the reaction pressure is 4-5 MPa, and the reaction time is 2-16 hours.

4. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 1, characterized in that: In the system, the molar ratio of ethylene glycol, ammonia and hydrogen is 1:(0.1-3):(0.1-4); The concentration of the ethylene glycol is 0.01-0.2 g / mL; The added amount of the catalyst is 1-10% of the mass of ethylene glycol.

5. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 1, characterized in that: The molar ratio of ethylene glycol, ammonia and hydrogen is 1:(0.5-3):(0.5-2.3); preferably, the molar ratio of ethylene glycol, ammonia and hydrogen is 1:3:2.

3.

6. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 1, characterized in that: In the system, the initial pressure value of ammonia is 0.1-0.6 MPa, and the initial pressure value of hydrogen is 0.2-1.5 MPa.

7. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 1, characterized in that: The catalyst comprises a catalyst carrier and active components loaded on the catalyst carrier, wherein the total loading amount of the active components is 0.1-30% of the catalyst mass, preferably 5-25%, more preferably 10%; the total loading amount of the active components is calculated as a single metal.

8. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 7, characterized in that: The active component is selected from one or more of Ru, Ni, Co, Pt, Mn, Zn, Fe, Cu and Pd.

9. The method for preparing ethylenediamine and piperazine from ethylene glycol according to claim 7, characterized in that: The catalyst carrier is selected from one or more of aluminum hydroxide, zirconium oxide, niobium oxide and S-1 molecular sieve.

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