A method for preparing ethyleneamines by hydrogenation of oxalate

Abstract

The present invention relates to a method for preparing ethyleneamines by hydrogenation of oxalate, and the method comprises the following steps: using oxalate, ammonia and hydrogen as raw materials, carrying out hydrogenation reaction under the action of a catalyst to obtain ethyleneamines. The method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention can significantly reduce the cost of raw materials, has a simple production process, can directly prepare ethyleneamine products with higher economic value, has high economic benefits and broad industrial prospects, can make oxalate have a higher conversion rate, and make the ethyleneamine products have a higher yield and selectivity.

Description

Technical Field

[0001] The invention relates to the field of fine chemicals, and in particular to a method for preparing ethyleneamines by hydrogenation of oxalate. Background Art

[0002] Ethyleneamines refer to acyclic polymers of ethylenediamine, including ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine or pentaethylenehexamine, among which diethylenetriamine is a widely used and expensive fine chemical product. Ethyleneamines also include cyclic amine products, such as piperazine, aminoethylpiperazine or hydroxyethylpiperazine. As an important intermediate of fine chemicals, ethyleneamines are widely used in organic synthesis, medicine, dyes, pesticides, chemical additives, rubber and plastic additives, organic solvents and epoxy resin curing agents.

[0003] Piperazine and its derivatives are important chemical raw materials and pharmaceutical intermediates, widely used in pesticides, medicines, synthetic resins, synthetic fibers, flame retardants, preservatives, rubber vulcanization accelerators, surfactants, power plant desulfurization and carbon dioxide capture. Among them, the most widely used in the pharmaceutical field, for example: anhydrous piperazine is an important intermediate for the production of quinolone antibacterial drugs such as norfloxacin, rifampicin and pipemidic acid; piperazine phosphate and piperazine citrate are used to produce anthelmintics; piperazine acetate is used to synthesize hormone drugs prednisolone sodium phosphate; N-methylpiperazine is an important intermediate for the synthesis of antibacterial drugs mepiquat, antipsychotic drugs trifluoperazine and ofloxacin; N-ethylpiperazine is mainly used to produce veterinary drugs ethylciprofloxacin; N-hydroxyethylpiperazine is an important intermediate for the synthesis of psychotropic drugs fluphenazine; 2-methylpiperazine is an important intermediate for the synthesis of lomefloxacin. According to the different water content, piperazine can be divided into anhydrous piperazine, trihydrate piperazine, hexahydrate piperazine and hexapenta piperazine. Among them, anhydrous piperazine is the most widely used, the most expensive in the market, and the main piperazine product in international trade. However, due to the limitation of production technology, the main piperazine product in industry is hexahydrate piperazine, which is difficult to dehydrate to prepare anhydrous piperazine, and the quality of the anhydrous piperazine directly prepared is not high. The above reasons cause the price of anhydrous piperazine products to remain high.

[0004] CN110438524B discloses a method for preparing diethylenetriamine by electrochemical reduction of iminodiacetonitrile. In this method, in an electrolytic cell, iminodiacetonitrile dissolved in a cathode liquid undergoes an electrolytic reaction on the cathode to generate diethylenetriamine. This method has a complex preparation process and a high production cost, which is not conducive to industrial promotion.

[0005] CN104628675A discloses a method for synthesizing piperazine and triethylenediamine. In this method, ethanolamine and ammonia are mixed and gasified, and an amination reaction is carried out in a fixed bed reactor at 300-350° C. to obtain piperazine and triethylenediamine. However, the method uses ethanolamine as a raw material, has a high production cost, and requires a high reaction temperature. The fluctuation of the reaction conditions has a great influence on the quality of the product.

[0006] CN104496939A discloses a method for preparing piperazine or alkylpiperazine by catalytic hydrogenation, wherein dihydroxyethylpiperazine or / and hydroxyethylpiperazine are used as raw materials, and piperazine or alkylpiperazine is prepared by catalytic hydrogenation under the action of a catalyst. The market price of the raw materials used in this method is relatively high, which is not conducive to the economic efficiency of production.

[0007] CN101906084A discloses a method for preparing piperazine and piperazine derivatives. The method uses ethylene glycol as a raw material, and simultaneously adds ammonia and hydrogen to react an ethylene glycol aqueous solution under the action of a catalyst to obtain piperazine and piperazine derivatives. Since the method is carried out in an aqueous solution, it is difficult to obtain anhydrous piperazine, and a higher operating pressure is required, and the process conditions are harsh.

[0008] Therefore, a method for producing ethyleneamines with simple operation, low cost and mild reaction conditions is provided, so as to obtain products such as anhydrous piperazine and diethylenetriamine with high economic value, which has important application value and economic value in the field of fine chemical production. Summary of the invention

[0009] In view of the above problems, the object of the present invention is to provide a method for preparing ethyleneamines by hydrogenation of oxalate. Compared with the prior art, the preparation method provided by the present invention uses oxalate as the main synthetic raw material, has low cost and simple process, can prepare products such as anhydrous piperazine and diethylenetriamine with high economic value, and has broad industrial prospects.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] The present invention provides a method for preparing ethyleneamines by hydrogenation of oxalate, the preparation method comprising the following steps:

[0012] Using oxalate, ammonia and hydrogen as raw materials, hydrogen amination reaction is carried out under the action of a catalyst to obtain ethyleneamine.

[0013] The ethyleneamines of the present invention mainly include anhydrous piperazine and diethylenetriamine, and also contain a small amount of by-products such as aminoethylpiperazine, hydroxyethylpiperazine, ethylenediamine or hydroxyethylethylenediamine.

[0014] In the present invention, oxalate, ammonia and hydrogen are used as raw materials, and ethyleneamine products mainly composed of anhydrous piperazine and diethylenetriamine are directly prepared through hydrogenation reaction. The oxalate used in the present invention is a basic organic chemical raw material with a wide range of sources. In the traditional method of preparing piperazine from ethanolamine, the market price of the ethanolamine used is relatively high, and the preparation conditions are very harsh, generally at a temperature of 300-400°C and a pressure of 10-25MPa. The price of the oxalate used in the present invention is much lower than that of chemical raw materials such as ethanolamine, and the present invention adopts lower temperature and pressure, and the preparation conditions are mild, which greatly reduces the requirements for industrial operating conditions. In the traditional method of preparing piperazine from ethylene glycol, it is generally carried out in an aqueous solution of ethylene glycol, it is difficult to obtain anhydrous piperazine, and higher operating pressure and temperature are required, the operating conditions are also relatively harsh, and ethylene glycol requires additional processes for preparation or purchase. Oxalic acid ester is the main raw material for preparing ethylene glycol. The present invention directly prepares anhydrous piperazine and diethylenetriamine products with high value from oxalic acid ester through hydrogenation reaction, which greatly shortens the process flow and saves process costs. In addition, the method of the present invention can make oxalic acid ester have a higher conversion rate, and make anhydrous piperazine and diethylenetriamine have higher selectivity and yield.

[0015] Preferably, the temperature of the hydroamination reaction is 140-260°C, for example, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C or 260°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] The present invention preferably controls the temperature of the hydrogenation reaction within a specific range, which is conducive to the reaction, improves the conversion rate of oxalate, and enables anhydrous piperazine and diethylenetriamine to have a higher yield and selectivity. At the same time, compared with the traditional piperazine preparation method, the reaction conditions provided by the present invention are milder, which can save production costs.

[0017] Preferably, the pressure of the hydroamination reaction is 0.5-5 MPa, for example, it can be 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 2.2 MPa, 2.5 MPa, 2.8 MPa, 3 MPa, 3.2 MPa, 3.5 MPa, 3.8 MPa, 4 MPa, 4.2 MPa, 4.5 MPa, 4.8 MPa or 5 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] The present invention preferably controls the pressure of the hydrogenation reaction within a specific range, which is beneficial to the reaction, improves the conversion rate of oxalate, and enables anhydrous piperazine and diethylenetriamine to have a higher yield and selectivity. At the same time, compared with the traditional piperazine preparation method, the reaction conditions provided by the present invention are milder, which can save production costs.

[0019] Preferably, the hydroamination reaction is carried out in a reactor or a fixed bed reactor.

[0020] Preferably, the reaction time of the oxalate in the reactor is 4-10 h, for example, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] The present invention preferably controls the reaction time of the oxalate ester in the reactor within a specific range, which can increase the reaction time of the reactants and the gas and is beneficial to the reaction.

[0022] Preferably, the space velocity of oxalate in the fixed bed reactor is 0.2-2h -1 , for example, it can be 0.2h -1 、0.4h -1 , 0.6h -1 , 0.8h -1 , 1h -1 , 1.2h -1 , 1.4h -1 , 1.6h -1 , 1.8h -1 or 2h -1 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0023] The present invention preferably controls the space velocity of the oxalate in the fixed bed reactor within a specific range, which can increase the contact time between the reactants and the catalyst and allow the reaction to proceed fully.

[0024] Preferably, the oxalate ester comprises dimethyl oxalate.

[0025] The present invention preferably controls the oxalate to be dimethyl oxalate because dimethyl oxalate is cheap, and the reaction of hydrogenating dimethyl oxalate to generate ethylene glycol and the amination reaction of ethylene glycol are connected in series to generate anhydrous piperazine in one step, making the process simpler.

[0026] Preferably, the molar ratio of ammonia to oxalate is (0.25-16):1, for example, it can be 0.25:1, 0.5:1, 0.75:1, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1 or 16:1, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably (5-16):1.

[0027] The present invention preferably controls the molar ratio of ammonia to oxalate within a specific range, so that the reaction can be fully carried out, which is beneficial to improving the conversion rate of oxalate and improving the selectivity and yield of products such as anhydrous piperazine and diethylenetriamine.

[0028] Preferably, the molar ratio of hydrogen to oxalate is (2-50):1, for example, 2:1, 4:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1 or 50:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably (20-50):1.

[0029] The present invention preferably controls the molar ratio of hydrogen to oxalate within a specific range, so that the reaction can be fully carried out, which is beneficial to improving the conversion rate of oxalate and improving the selectivity and yield of products such as anhydrous piperazine and diethylenetriamine.

[0030] Preferably, the mass of the catalyst is 0.1-20% of the mass of the oxalate, for example, it can be 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 0.5-5%.

[0031] The present invention preferably controls the percentage of the mass of the catalyst to the mass of the oxalate within a specific range, which can increase the reaction rate, is beneficial to increasing the conversion rate of the oxalate, and improves the selectivity and yield of products such as anhydrous piperazine and diethylenetriamine.

[0032] Preferably, the active components of the catalyst include Ni and Cu.

[0033] Preferably, the active components of the catalyst also include any one or a combination of at least two of Co, Mn, Ce, Mg, La, Fe or Zn, wherein typical but non-limiting combinations include a combination of Mn and Ce, a combination of La and Mg, or a combination of Fe and Zn, etc.

[0034] Preferably, the catalyst carrier includes any one of activated carbon, Al2O3 or SiO2.

[0035] Preferably, the mass of the active component is 1-30% of the mass of the catalyst, for example, it can be 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28% or 30%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In the present invention, the catalyst can be prepared by any commonly used catalyst preparation method in the art, such as any one of a precipitation method, an impregnation method or a hydrothermal method or a combination of at least two thereof.

[0037] As a preferred technical solution of the present invention, the method comprises the following steps:

[0038] Oxalate, ammonia and hydrogen are used as raw materials, and a hydrogenation reaction is carried out at 140-260°C and 0.5-5MPa under the action of a catalyst to obtain ethyleneamine. The hydrogenation reaction is carried out in a reactor or a fixed bed reactor. The reaction time of the oxalate in the reactor is 4-10h; the space velocity of the oxalate in the fixed bed reactor is 0.2-2h -1 ;

[0039] The oxalate comprises dimethyl oxalate; the molar ratio of ammonia to oxalate is (0.25-16):1; the molar ratio of hydrogen to oxalate is (2-50):1; the mass of the catalyst is 0.1-20% of the mass of the oxalate;

[0040] The active components of the catalyst include Ni and Cu, and also include any one or a combination of at least two of Co, Mn, Ce, Mg, La, Fe or Zn; the carrier of the catalyst includes any one of activated carbon, Al2O3 or SiO2; the mass of the active components is 1-30% of the mass of the catalyst.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention can significantly reduce the cost of raw materials. Anhydrous piperazine and diethylenetriamine are synthesized in one step by hydrogenation of oxalate. The production process is simple and ethyleneamine products with higher economic value can be directly prepared. The method has higher economic benefits and broad industrial prospects.

[0043] (2) The method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention can achieve an oxalate conversion rate of more than 43.2%, an ethyleneamine selectivity of more than 34.9%, anhydrous piperazine selectivity of more than 20.2%, a yield of more than 9.1%, a diethylenetriamine selectivity of more than 8.8%, and a yield of more than 3.8%; under optimal conditions, the oxalate can have a higher conversion rate, which can reach more than 86.1%, and a higher selectivity for ethyleneamine, which can reach more than 82.4%, especially the selectivity for anhydrous piperazine can reach more than 42.4%, the yield can reach more than 36.5%, the selectivity for diethylenetriamine can reach more than 30.4%, and the yield can reach more than 26.2%.

[0044] (3) The reaction temperature and pressure required for the method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention are much lower than those of the traditional process, and the reaction conditions are milder, which is conducive to industrial production. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] Example 1

[0047] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate, the method comprising the following steps:

[0048] 0.2 g of dimethyl oxalate and a catalyst are placed in a high-pressure reactor, the reactor is sealed, the air tightness of the reactor is checked with nitrogen, and the air inside is replaced; ammonia and hydrogen are introduced, the molar ratio of ammonia to dimethyl oxalate is 12:1, the molar ratio of hydrogen to dimethyl oxalate is 30:1, and a hydrogenation reaction is carried out in the high-pressure reactor at 180° C. and 3 MPa, the reaction time of dimethyl oxalate is 6 hours, and ethyleneamines are obtained; the ethyleneamines include anhydrous piperazine and diethylenetriamine;

[0049] The mass of the catalyst is 5% of the mass of dimethyl oxalate, the active components of the catalyst are Ni, Cu and Co, wherein the molar ratio of Ni, Cu and Co is 3:2:1, the carrier is Al2O3, and the mass of Ni, Cu and Co is 25% of the mass of the catalyst.

[0050] Example 2

[0051] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate, the method comprising the following steps:

[0052] 0.2 g of dimethyl oxalate and a catalyst are placed in a high-pressure reactor, the reactor is sealed, the air tightness of the reactor is checked with nitrogen, and the air inside is replaced; ammonia and hydrogen are introduced, the molar ratio of ammonia to dimethyl oxalate is 16:1, and the molar ratio of hydrogen to dimethyl oxalate is 50:1, and a hydrogenation reaction is carried out in the high-pressure reactor at 140° C. and 5 MPa. The reaction time of dimethyl oxalate is 5 hours to obtain ethyleneamines; the ethyleneamines include anhydrous piperazine and diethylenetriamine;

[0053] The mass of the catalyst is 2.5% of the mass of dimethyl oxalate, the active components of the catalyst are Ni, Cu and Ce, wherein the molar ratio of Ni, Cu and Ce is 3:2:1, the carrier is Al2O3, and the mass of Ni, Cu and Ce is 1% of the mass of the catalyst.

[0054] Example 3

[0055] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate, the method comprising the following steps:

[0056] 0.2 g of dimethyl oxalate and a catalyst are placed in a high-pressure reactor, the reactor is sealed, the air tightness of the reactor is checked with nitrogen, and the air inside is replaced; ammonia and hydrogen are introduced, the molar ratio of ammonia to dimethyl oxalate is 5:1, and the molar ratio of hydrogen to dimethyl oxalate is 20:1, and a hydrogenation reaction is carried out in the high-pressure reactor at 260° C. and 0.5 MPa, and the reaction time of dimethyl oxalate is 10 hours to obtain ethyleneamines; the ethyleneamines include anhydrous piperazine and diethylenetriamine;

[0057] The mass of the catalyst is 0.5% of the mass of dimethyl oxalate, the active components of the catalyst are Ni, Cu and Mn, wherein the molar ratio of Ni, Cu and Mn is 3:2:1, the carrier is Al2O3, and the mass of Ni, Cu and Mn is 30% of the mass of the catalyst.

[0058] Example 4

[0059] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate. The method is different from that of Embodiment 1 only in that the molar ratio of ammonia to dimethyl oxalate is 3:1.

[0060] Example 5

[0061] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate. The method is different from that of Embodiment 1 only in that the molar ratio of hydrogen to dimethyl oxalate is 10:1.

[0062] Example 6

[0063] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate, the method being different from that of embodiment 1 only in that the temperature of the hydrogenation reaction is 130°C.

[0064] Example 7

[0065] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate, and the method is different from that of Embodiment 1 only in that the pressure of the hydrogenation reaction is 0.2 MPa.

[0066] Example 8

[0067] This embodiment provides a method for preparing ethyleneamines by hydrogenation of oxalate. The method is different from that of Embodiment 1 only in that the reaction time of dimethyl oxalate is 3 h.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing piperazine, the method comprising: introducing ethanolamine and ammonia into a fixed bed reactor, reacting under the conditions of a reaction pressure of 4 MPa, a temperature of 320° C., a reaction contact time of 22 s, and a mass ratio of ammonia to ethanolamine of 8:1, to obtain piperazine;

[0070] The active components of the catalyst are Ni and Fe, the carrier is Al2O3, and the mass percentage of Ni and Fe is 0.25% of the catalyst.

[0071] Compared with Comparative Example 1, the reaction temperature and pressure of Example 1 are lower than those of Comparative Example 1, and the price of the oxalate used in Example 1 is lower than that of ethanolamine. Therefore, the method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention has low production cost, milder reaction conditions, and lower requirements on production conditions.

[0072] Comparative Example 2

[0073] This comparative example provides a method for preparing piperazine, which comprises: introducing a 50% by mass ethylene glycol aqueous solution into a fixed bed reactor at a flow rate of 30 g / h, reacting under the action of a catalyst, the reaction temperature being 230° C., the hydrogen pressure being 8 MPa, the hydrogen flow rate being 8.2 L / h, and the liquid ammonia flow rate being 40 g / h, to obtain piperazine;

[0074] The active components of the catalyst are Ni and Cu, the carrier is Al2O3, the mass percentage of Ni is 10% of the catalyst, and the mass percentage of Cu is 15% of the catalyst.

[0075] Compared with Comparative Example 2, the reaction temperature and pressure of Example 1 are lower than those of Comparative Example 2, and the reaction conditions are milder; and the ethylene glycol used in Comparative Example 2 requires additional process preparation or purchase, while oxalate is the main raw material for preparing ethylene glycol, so the preparation process of Example 1 is simpler and the cost is lower; Example 1 can prepare anhydrous piperazine, while Comparative Example 2 is reacted in an ethylene glycol aqueous solution, and it is difficult to prepare anhydrous piperazine. Therefore, the method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention greatly shortens the process flow, is simple to operate, and is low in cost, and can prepare anhydrous piperazine products with higher value.

[0076] The ethyleneamines prepared in Examples 1-8 were analyzed by gas chromatography (RTX-5 column, FID detector). The results are shown in Table 1.

[0077] Table 1

[0078]

[0079] From Table 1, we can see the following points:

[0080] (1) It can be seen from Examples 1-8 that the method for preparing ethyleneamines by hydrogenation of oxalate provided in Examples 1-8 enables the conversion rate of oxalate to reach above 43.2%, the selectivity of ethyleneamine to reach above 34.9%, the selectivity of anhydrous piperazine to reach above 20.2%, the yield to reach above 9.1%, the selectivity of diethylenetriamine to reach above 8.8%, and the yield to reach above 3.8%; under preferred conditions, the conversion rate of oxalate can be made higher, which can reach above 86.1%, the selectivity for ethyleneamine is higher, which can reach above 82.4%, especially the selectivity for anhydrous piperazine can reach above 42.4%, the yield can reach above 36.5%, the selectivity for diethylenetriamine can reach above 30.4%, and the yield can reach above 26.2%.

[0081] (2) It can be seen from the data of Example 1 and Examples 4-5 that the molar ratio of ammonia to dimethyl oxalate in Example 1 is 12:1, and the molar ratio of hydrogen to dimethyl oxalate is 30:1. Compared with the molar ratio of ammonia to dimethyl oxalate of 3:1 in Example 4 and the molar ratio of hydrogen to dimethyl oxalate of 10:1 in Example 5, the conversion rate of oxalate, the selectivity and yield of anhydrous piperazine, and the selectivity and yield of diethylenetriamine in Examples 4 and 5 are all lower than those in Example 1. This shows that the present invention preferably controls the molar ratio of ammonia to oxalate and the molar ratio of hydrogen to oxalate within a specific range ((0.25-16):1 and (2-50):1, respectively), which can improve the conversion rate of oxalate and the selectivity of ethyleneamines, especially improve the selectivity and yield of anhydrous piperazine and diethylenetriamine.

[0082] (3) It can be seen from the data of Example 1 and Example 6 that the temperature of the hydroamination reaction in Example 1 is 180°C. Compared with the temperature of the hydroamination reaction in Example 6 being 130°C, the conversion rate of oxalate, the selectivity and yield of anhydrous piperazine, and the selectivity and yield of diethylenetriamine in Example 6 are all lower than those in Example 1. This shows that the present invention preferably controls the temperature of the hydroamination reaction within a specific range (140-260°C), which can improve the conversion rate of oxalate and the selectivity of ethyleneamines, especially improve the selectivity and yield of anhydrous piperazine and diethylenetriamine.

[0083] (4) It can be seen from the data of Example 1 and Example 7 that the pressure of the hydroamination reaction in Example 1 is 3 MPa, while the pressure of the hydroamination reaction in Example 7 is 0.2 MPa. The conversion rate of oxalate, the selectivity and yield of anhydrous piperazine, and the selectivity and yield of diethylenetriamine in Example 7 are all lower than those in Example 1. This shows that the present invention preferably controls the pressure of the hydroamination reaction within a specific range (0.5-5 MPa), which can improve the conversion rate of oxalate and the selectivity of ethyleneamines, especially improve the selectivity and yield of anhydrous piperazine and diethylenetriamine.

[0084] (5) It can be seen from the data of Example 1 and Example 8 that the reaction time of dimethyl oxalate in Example 1 is 6 h, while the reaction time of dimethyl oxalate in Example 8 is 3 h. The conversion rate of oxalate, the selectivity and yield of anhydrous piperazine, and the selectivity and yield of diethylenetriamine in Example 8 are all lower than those in Example 1. This shows that the present invention preferably controls the reaction time of dimethyl oxalate within a specific range (4-10 h), which can improve the conversion rate of oxalate and the selectivity of ethyleneamines, especially improve the selectivity and yield of anhydrous piperazine and diethylenetriamine.

[0085] In summary, the method for preparing ethyleneamines by hydrogenation of oxalate provided by the present invention has low cost, simple operation, mild reaction conditions, and can improve the conversion rate of oxalate and the selectivity of ethyleneamines, especially improve the selectivity and yield of anhydrous piperazine and diethylenetriamine.

[0086] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing ethyleneamines by hydrogenation of oxalate, characterized in that: The method comprises the following steps: Using oxalate, ammonia and hydrogen as raw materials, a hydrogenation reaction is carried out under the action of a catalyst to obtain ethyleneamine; The active components of the catalyst include Ni and Cu; the active components of the catalyst also include any one or a combination of at least two of Co, Mn, Ce, Mg, La, Fe or Zn.

2. The method according to claim 1, characterized in that The temperature of the hydroamination reaction is 140-260°C.

3. The method according to claim 1 or 2, characterized in that: The pressure of the hydrogenation reaction is 0.5-5 MPa.

4. The method according to claim 1, characterized in that: The hydroamination reaction is carried out in a reactor or a fixed bed reactor.

5. The method according to claim 4, characterized in that The reaction time of the oxalate in the reactor is 4-10h.

6. The method according to claim 4, characterized in that The space velocity of oxalate in the fixed bed reactor is 0.2-2h -1 .

7. The method according to claim 1, characterized in that The oxalate ester is dimethyl oxalate.

8. The method according to claim 1, characterized in that The molar ratio of ammonia to oxalate is (0.25-16):

1.

9. The method according to claim 8, characterized in that The molar ratio of ammonia to oxalate is (5-16):

1.

10. The method according to claim 1, characterized in that The molar ratio of hydrogen to oxalate is (2-50):

1.

11. The method according to claim 10, characterized in that The molar ratio of hydrogen to oxalate is (20-50):

1.

12. The method according to claim 1, characterized in that The mass of the catalyst is 0.1-20% of the mass of the oxalate.

13. The method according to claim 12, characterized in that The mass of the catalyst is 0.5-5% of the mass of the oxalate.

14. The method according to claim 1, characterized in that The carrier of the catalyst includes any one of activated carbon, Al2O3 or SiO2.

15. The method according to claim 1, characterized in that The mass of the active component is 1-30% of the mass of the catalyst.

16. The method according to claim 1, characterized in that The method comprises the following steps: Oxalate, ammonia and hydrogen are used as raw materials, and a hydrogenation reaction is carried out at 140-260°C and 0.5-5MPa under the action of a catalyst to obtain ethyleneamine. The hydrogenation reaction is carried out in a reactor or a fixed bed reactor. The reaction time of the oxalate in the reactor is 4-10h; the space velocity of the oxalate in the fixed bed reactor is 0.2-2h -1 ; The oxalate is dimethyl oxalate; the molar ratio of ammonia to oxalate is (0.25-16):1; the molar ratio of hydrogen to oxalate is (2-50):1; the mass of the catalyst is 0.1-20% of the mass of the oxalate; The active components of the catalyst include Ni and Cu, and also include any one or a combination of at least two of Co, Mn, Ce, Mg, La, Fe or Zn; the carrier of the catalyst includes any one of activated carbon, Al2O3 or SiO2; the mass of the active components is 1-30% of the mass of the catalyst.

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