A method for preparing ethanolamine

Abstract

The present invention provides a preparation method of ethanolamine, which relates to the technical field of the preparation of ethanolamine. First, the present invention uses a catalyst to promote the oxidation of ethylene glycol and obtain a mixed solution of glycolaldehyde, and then the mixed solution of glycolaldehyde is mixed with ammonia water and subjected to reductive amination to obtain ethanolamine. The synthesis process of the present invention has mild reaction conditions, no toxic by-products are generated, the conversion rate of ethylene glycol during the reaction process is as high as 80%, and the selectivity of ethanolamine is as high as 60%. It is a green preparation method of ethanolamine that is efficient, economical and easy to scale up production, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of ethanolamine, and particularly relates to a method for preparing ethanolamine. Background Art

[0002] Ethanolamine is an important organic compound, which is widely used in the fields of chemical industry, medicine, pesticides, etc. In traditional ethanolamine synthesis processes, ethanolamine is mainly prepared by the addition reaction of ethylene oxide and ammonia water. However, this method has problems such as harsh reaction conditions, high energy consumption, and toxic by-products. In addition, ethylene oxide is a toxic and harmful substance, and there are safety hazards in its production and use processes.

[0003] In recent years, with the rise of the concept of green chemistry, the use of biomass as a raw material to synthesize chemicals has become a research hotspot. Carbohydrates in biomass can be converted into various valuable chemicals through fermentation or enzymatic hydrolysis, including the precursor substances of ethanolamine. Therefore, using biomass raw materials such as glucose to be converted into ethanol through microbial fermentation and then further converted into ethanolamine becomes a safer and more environmentally friendly method for preparing ethanolamine. However, in this method, the conversion efficiency of biomass is relatively low and the production cost is relatively high.

[0004] The invention patent with the publication number CN103664649A discloses a method for preparing monoethanolamine starting from ethylene glycol. Its reaction system consists of ethylene glycol, liquid ammonia, and hydrogen. The catalyst uses one or several of alumina, silica, activated carbon, and molecular sieve as carriers, and loads at least two of the active components Ru, Ni, Pd, Pt, Co, Mo, Fe, Mn, Sn, Zn, and B. Ethylene glycol and liquid ammonia can be highly active and selectively converted into monoethanolamine under the action of the catalyst, and ethylenediamine, piperazine, etc. are co-produced. This method has simple operation and high monoethanolamine yield. However, this method requires loading at least two active components to prepare the catalyst, resulting in an increase in catalyst cost and a relatively low conversion rate of ethylene glycol.

[0005] Therefore, it is necessary to develop a green preparation method for ethanolamine that is efficient, economical, and easy to scale up production, so as to improve the conversion rate of ethylene glycol and the yield of ethanolamine and reduce the production cost of ethanolamine. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing ethanolamine. This method uses ethylene glycol as a raw material and obtains ethanolamine through two-step reactions. The reaction conditions are mild, no toxic by-products are generated, and the raw material conversion rate and product selectivity are high. It is a green preparation method for ethanolamine that is efficient, economical, and easy to scale up production.

[0007] The method for preparing ethanolamine of the present invention includes the following steps:

[0008] First, a catalyst is used to promote the oxidation of ethylene glycol to obtain a glycolaldehyde mixture, and then the glycolaldehyde mixture is mixed with ammonia water and subjected to reductive amination to obtain ethanolamine.

[0009] Preferably, the catalyst is a supported single-metal catalyst, including a carrier and an active component. The carrier is at least one of metal oxides, molecular sieves, and activated carbon; the metal oxides are at least one of Al 2 O 3 、SiO 2 、TiO 2 ; the molecular sieve is NaY and / or ZSM-5; the active component is Co, Fe, Al, Cr, Au, Ag, Ru, or Pd.

[0010] Preferably, the catalyst is prepared by an impregnation method.

[0011] Preferably, the catalyst is subjected to reduction activation treatment before use. The main steps of the reduction activation treatment include: heat-treating the catalyst in a 30% H 2 / Ar atmosphere, then cooling to room temperature and adding an acid solution, stirring at a certain temperature for a period of time, and then cooling, centrifuging, washing, and drying.

[0012] Preferably, the oxidation of ethylene glycol is carried out in an oxygen atmosphere. The mass-volume ratio of the catalyst to the ethylene glycol aqueous solution is 1 g:(100~200)mL; the concentration of the ethylene glycol aqueous solution is 0.1~5 mol / L; the oxygen pressure is 0.5~2.0 MPa; the reaction temperature is 50°C~80°C, and the reaction time is 2.5~25 h; the reaction is carried out under stirring conditions, and the rotation speed is 1000 rpm.

[0013] Preferably, the reductive amination is carried out in a hydrogen atmosphere, and the hydrogen pressure is 3.0~5.0 MPa; the concentration of the ammonia water is 0.1~5 mol / L; the volume ratio of the glycolaldehyde mixture to the ammonia water is 1:1; the reaction temperature is room temperature, and the reaction time is 2.5~25 h.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are:

[0015] The present invention carries out reductive amination under mild conditions to produce the target product ethanolamine. This synthesis process has mild reaction conditions, no toxic by-products are generated, the conversion rate of ethylene glycol during the reaction is as high as 80%, and the selectivity of ethanolamine is as high as 60%. It is a green preparation method of ethanolamine that is efficient, economical, and easy to scale up production, and has broad application prospects. Specific Embodiments

[0016] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] The present invention provides a method for preparing ethanolamine, which includes the following steps:

[0018] First, a catalyst is used to promote the oxidation of ethylene glycol to obtain a glycolaldehyde mixture, and then the glycolaldehyde mixture is mixed with ammonia water and subjected to reductive amination to obtain ethanolamine.

[0019] The preparation process of ethanolamine in the present invention is carried out in two steps. The first step is the oxidation of ethylene glycol to prepare glycolaldehyde. In this reaction process, the present invention promotes the oxidation of ethylene glycol by using a specific catalyst, significantly improving the conversion rate of ethylene glycol. Under the conditions defined in the present invention, the conversion rate of ethylene glycol can reach more than 80%, showing a very significant improvement compared with the prior art.

[0020] In some specific embodiments of the present invention, the catalyst is a supported single-metal catalyst, which includes a carrier and an active component. Among them, the carrier is at least one of metal oxides, molecular sieves, and activated carbon; the metal oxide is at least one of Al 2 O 3 、SiO 2 、TiO 2 , the molecular sieve is NaY and / or ZSM-5; the active component is Co, Fe, Al, Cr, Au, Ag, Ru, or Pd. The single-metal catalyst of the present invention utilizes the synergistic effect between the active component and the carrier to improve the conversion rate of ethylene glycol, providing better activity, selectivity, and stability for the subsequent reductive amination.

[0021] The supported catalyst of the present invention is prepared by the impregnation method. The impregnation can be carried out in one step or multiple steps. The main steps for preparing the catalyst by the impregnation method include: preparing a metal salt solution containing the active component with the required concentration, impregnating 20 mL of the metal salt solution onto 1 g of the carrier or intermediate catalyst at a certain temperature, and then drying, calcining, and cooling. Among them, the concentration of the metal in the metal salt solution of the active component is 1.0×10 -4 ~1.0×10 -3 g / mL; the impregnation temperature is 30°C~60°C, the impregnation time is 8~16 h, and the preferred impregnation time is 12 h; drying and calcining are carried out in an air atmosphere, the drying temperature is 40°C~70°C, and the drying time is at least 12 h; the calcination temperature is 500°C~600°C, and the calcination time is 8~9 h.

[0022] Before the catalyst of the present invention is used, it needs to be reduced and activated. The main steps of the reduction activation include: heat-treating the catalyst in a 30% H 2 / Ar atmosphere, then cooling to room temperature and adding an acid solution, stirring for a period of time at a certain temperature, and then cooling, centrifuging, washing, and drying. Among them, the acid solution is a citric acid solution, glycolic acid solution, oxalic acid solution, propionic acid solution, lactic acid solution, and the concentration of the acid solution is 5 wt%; the heat-treatment temperature is 400°C to 600°C, and the heat-treatment time is 7 to 10 h; the stirring temperature is 90°C, the stirring time is 6 h, and the stirring rate is 300 to 500 rpm; the washing is carried out with deionized water, and the number of washing times is at least 3 times; the drying temperature is 70°C, and the drying time is at least 12 h.

[0023] The first step of the present invention is the oxidation of ethylene glycol to prepare glycolaldehyde. The main steps include: mixing the catalyst with an ethylene glycol aqueous solution and carrying out an oxidation reaction in an oxygen atmosphere to obtain a glycolaldehyde mixed solution. Among them, the mass-volume ratio of the catalyst to the ethylene glycol aqueous solution is 1 g:(100 - 200) mL; the concentration of the ethylene glycol aqueous solution is 0.1 - 5 mol / L, preferably the concentration of the ethylene glycol aqueous solution is 1 mol / L; the oxygen pressure is 0.5 - 2.0 MPa, preferably the oxygen pressure is 1 MPa; the reaction temperature is 50°C to 80°C, preferably the reaction temperature is 60°C to 70°C, the reaction time is 2.5 - 25 h, preferably the reaction time is 15 - 20 h; the reaction is preferably carried out under stirring conditions, and the rotation speed is 1000 rpm.

[0024] The second step of the present invention is the reductive amination to prepare ethanolamine. The main steps include: mixing the glycolaldehyde mixed solution with ammonia water and carrying out reductive amination in a hydrogen atmosphere to obtain ethanolamine. Among them, the concentration of ammonia water is 0.1 - 5 mol / L, preferably the concentration of ammonia water is 1 - 2 mol / L; the volume ratio of the glycolaldehyde mixed solution to ammonia water is 1:1; the hydrogen pressure is 3.0 - 5.0 MPa; the reaction temperature is room temperature, and the reaction time is 2.5 - 25 h.

[0025] In order to further illustrate the present invention, the following examples are used for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0026] Unless otherwise specified, all experiments are repeated 3 times, and the results are expressed as averages.

[0027] Example 1 A method for preparing ethanolamine, the specific steps are as follows:

[0028] S1. Take 0.1 g of Co / Al 2 O 3The catalyst was mixed with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. The resulting mixture was added to a 25 mL autoclave, filled with oxygen to 1 MPa, the rotation speed was adjusted to 1000 rpm, the reaction temperature was adjusted to 70 °C, and the reaction was carried out for 15 h to obtain a glycolaldehyde mixture. The composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 1-1;

[0029] S2. The glycolaldehyde mixture in S1 was mixed with ammonia water with a concentration of 1 mol / L, and the volume ratio of the glycolaldehyde mixture to ammonia water was 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde was reductively aminated to ethanolamine at room temperature, and the product was analyzed by high-performance liquid chromatography. The specific results are shown in Table 1-2.

[0030] Table 1-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Co / Al 2 O 3 catalyst

[0031]

[0032] Table 1-2. Reductive amination reaction results of the reaction solution at room temperature

[0033]

[0034] The preparation method of the Co / Al 2 O 3 catalyst is as follows:

[0035] Cobalt nitrate was dissolved in deionized water to obtain a precursor aqueous solution with a Co concentration of 1.0×10 -3 g / mL. 20 mL of the impregnation solution was added to 1 g of the carrier Al 2 O 3 . After stirring evenly at 50 °C for 12 h, it was impregnated for 12 h, dried in an oven at 70 °C for 12 h. The obtained catalyst was ground until there were no obvious particles, and then calcined at 500 °C for 8 h and cooled to room temperature; in a 30% H 2 / Ar atmosphere, the calcined catalyst was reduced at 400 °C for 7 h and cooled to room temperature. Then it was added to 25 mL of a 5% citric acid solution by mass, stirred evenly at 90 °C for 6 h, and the stirring rate was 500 rpm. After cooling to room temperature, the cooled slurry was centrifuged. The filter cake obtained after centrifugation was washed with deionized water and centrifuged three times, and then dried at 70 °C for 12 h. After drying, the finished catalyst was obtained.

[0036] Example 2 A method for preparing ethanolamine, the specific steps are as follows:

[0037] S1. Mix 0.1 g of Pd / NaY catalyst with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. Add the resulting mixture to a 25 mL high-pressure reactor, fill it with oxygen to 1 MPa, adjust the rotation speed to 1000 rpm, adjust the reaction temperature to 60 °C, and react for 15 h to obtain a glycolaldehyde mixture. Analyze the components of the solution by high-performance liquid chromatography, and calculate the conversion rate and selectivity. The specific results are shown in Table 2-1;

[0038] S2. Mix the glycolaldehyde mixture in S1 with ammonia water with a concentration of 2 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water is 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde undergoes reductive amination to form ethanolamine at room temperature. Analyze the products by high-performance liquid chromatography. The specific results are shown in Table 2-2.

[0039] Table 2-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Pd / NaY catalyst

[0040] Table 2-2. Reductive amination reaction results of the reaction solution at room temperature

[0041]

[0042] The preparation method of the Pd / NaY catalyst is as follows:

[0043] Dissolve chloropalladic acid in deionized water to obtain a precursor aqueous solution with a Pd concentration of 1.0×10 -3 g / mL. Add 20 mL of the impregnation solution to 1 g of the carrier NaY, stir evenly at 60 °C for 12 h, dry in an oven at 70 °C for 12 h, grind the obtained catalyst until there are no obvious particles, and then calcine at 500 °C for 8 h and cool to room temperature; in a 30% H 2 / Ar atmosphere, reduce the calcined catalyst at 400 °C for 8 h and cool to room temperature. Then add it to 25 mL of a 5% glycolic acid solution by mass, stir evenly at 90 °C for 6 h, with a stirring rate of 500 rpm, cool to room temperature, centrifuge the cooled slurry, wash the obtained filter cake with deionized water and centrifuge three times, and then dry at 70 °C for 12 h. After drying, the finished catalyst is obtained.

[0044] Example 3 A preparation method of ethanolamine, the specific steps are as follows:

[0045] S1. Mix 0.1 g of Au / TiO 2The catalyst was mixed with 15 mL of an aqueous ethylene glycol solution with a concentration of 2 mol / L. The resulting mixture was added to a 25 mL high-pressure reactor, filled with oxygen to 1 MPa, the rotation speed was adjusted to 1000 rpm, the reaction temperature was adjusted to 70 °C, and the reaction was carried out for 20 h. The composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 3-1;

[0046] S2. The glycolaldehyde mixture in S1 was mixed with ammonia water with a concentration of 2 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water was 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde was reductively aminated to ethanolamine at room temperature to obtain a glycolaldehyde mixture, and the product was analyzed by high-performance liquid chromatography. The specific results are shown in Table 3-2.

[0047] Table 3-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Au / TiO 2 catalyst

[0048] Table 3-2. Reductive amination reaction results of the reaction solution at room temperature

[0049]

[0050] The preparation method of the Au / TiO 2 catalyst is as follows:

[0051] Chloroauric acid was dissolved in deionized water to obtain a precursor aqueous solution with a Au concentration of 1.0×10 -3 g / mL. 20 mL of the impregnation solution was added to 1 g of the carrier TiO 2 . After being fully and evenly stirred at 50 °C, it was impregnated for 12 h, dried in an oven at 70 °C for 12 h. The obtained catalyst was ground until there were no obvious particles, and then calcined at 600 °C for 8 h and cooled to room temperature; in a 30% H 2 / Ar atmosphere, the calcined catalyst was reduced at 500 °C for 8 h and cooled to room temperature. Then it was added to 25 mL of a 5% mass fraction oxalic acid solution, and fully and evenly stirred at 90 °C for 6 h. The stirring rate was 500 rpm, and it was cooled to room temperature. The cooled slurry was centrifuged, and the obtained filter cake was washed with deionized water and centrifuged three times, and then dried at 70 °C for 12 h. After drying, the finished catalyst was obtained.

[0052] Example 4 A preparation method of ethanolamine, the specific steps are as follows:

[0053] S1. 0.1 g of Ru / TiO 2The catalyst was mixed with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. The resulting mixture was added to a 25 mL high-pressure reactor, filled with oxygen to 1 MPa, the rotation speed was adjusted to 1000 rpm, the reaction temperature was adjusted to 70 °C, and the reaction was carried out for 15 h. The composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 4-1;

[0054] S2. The glycolaldehyde mixture in S1 was mixed with ammonia water with a concentration of 2 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water was 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde was reductively aminated to ethanolamine at room temperature to obtain a glycolaldehyde mixture, and the product was analyzed by high-performance liquid chromatography. The specific results are shown in Table 4-2.

[0055] Table 4-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Ru / TiO 2 catalyst

[0056] Table 4-2. Reductive amination reaction results of the reaction solution at room temperature

[0057]

[0058] The preparation method of the Ru / TiO 2 catalyst is as follows:

[0059] Take ruthenium chloride and dissolve it in deionized water to obtain a precursor aqueous solution with a Ru concentration of 1.0×10 -3 g / mL. Add 20 mL of the impregnation solution to 1 g of the carrier TiO 2 . After stirring evenly at 60 °C for 12 h, impregnate for 12 h, dry in an oven at 70 °C for 12 h. Grind the obtained catalyst until there are no obvious particles, and then calcine at 600 °C for 9 h and cool to room temperature; in a 30% H 2 / Ar atmosphere, the calcined catalyst was reduced at 400 °C for 9 h and cooled to room temperature. Then it was added to 25 mL of a 5% (mass fraction) propionic acid solution, and stirred evenly at 90 °C for 6 h with a stirring rate of 500 rpm. Cool to room temperature, centrifuge the cooled slurry, wash the centrifuged filter cake three times with deionized water and then dry at 70 °C for 12 h. After drying, the finished catalyst was obtained.

[0060] Example 5 A preparation method of ethanolamine, the specific steps are as follows:

[0061] S1. Mix 0.1 g of Ag / C catalyst with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. Add the resulting mixture to a 25 mL high-pressure reactor, fill it with oxygen to 1 MPa, adjust the rotation speed to 1000 rpm, adjust the reaction temperature to 70 °C, and react for 20 h to obtain a glycolaldehyde mixture. Analyze the components of the solution by high-performance liquid chromatography, and calculate the conversion rate and selectivity. The specific results are shown in Table 5-1.

[0062] S2. Mix the glycolaldehyde mixture in S1 with ammonia water with a concentration of 1 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water is 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde undergoes reductive amination to form ethanolamine at room temperature. Analyze the products by high-performance liquid chromatography. The specific results are shown in Table 5-2.

[0063] Table 5-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Au / C catalyst

[0064] Table 5-2. Reductive amination reaction results of the reaction solution at room temperature

[0065]

[0066] The preparation method of the Ag / C catalyst is as follows:

[0067] Dissolve silver chloride in deionized water to obtain a precursor aqueous solution with a Ag concentration of 1.0×10 -3 g / mL. Add 20 mL of the impregnation solution to 1 g of the carrier activated carbon. Stir evenly at 70 °C for 12 h, dry in an oven at 40 °C for 12 h. Grind the obtained catalyst until there are no obvious particles, and then calcine at 500 °C for 9 h and cool to room temperature; in a 30% H 2 / Ar atmosphere, reduce the calcined catalyst at 400 °C for 8 h and cool to room temperature. Then add it to 25 mL of a 5% citric acid solution by mass, stir evenly at 90 °C for 6 h, with a stirring rate of 500 rpm, and cool to room temperature. Centrifuge the cooled slurry, wash the obtained filter cake with deionized water and centrifuge three times, and then dry at 70 °C for 12 h. After drying, the finished catalyst is obtained.

[0068] Example 6 A preparation method of ethanolamine, the specific steps are as follows:

[0069] S1. Mix 0.1 g of Fe / SiO 2The catalyst was mixed with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. The resulting mixture was added to a 25 mL high-pressure reactor, filled with oxygen to 1 MPa, the rotation speed was adjusted to 1000 rpm, the reaction temperature was adjusted to 70 °C, and the reaction was carried out for 15 h. The composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 6-1;

[0070] S2. The glycolaldehyde mixture in S1 was mixed with ammonia water with a concentration of 1 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water was 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde was reductively aminated to ethanolamine at room temperature to obtain a glycolaldehyde mixture, and the product was analyzed by high-performance liquid chromatography. The specific results are shown in Table 6-2.

[0071] Table 6-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Fe / SiO 2 catalyst

[0072] Table 6-2. Reductive amination reaction results of the reaction solution at room temperature

[0073]

[0074] The preparation method of the Fe / SiO 2 catalyst is as follows:

[0075] Ferric nitrate was dissolved in deionized water to obtain a precursor aqueous solution with a Ag concentration of 2.5×10 -4 g / mL. 20 mL of the impregnation solution was added to 1 g of the carrier SiO 2 . After stirring evenly at 50 °C for 12 h, it was impregnated for 12 h, dried in an oven at 70 °C for 12 h. The obtained catalyst was ground until there were no obvious particles, and then calcined at 500 °C for 9 h and cooled to room temperature; in a 30% H 2 / Ar atmosphere, the calcined catalyst was reduced at 600 °C for 9 h and cooled to room temperature. Then it was added to 25 mL of a lactic acid solution with a mass fraction of 5%, and stirred evenly at 90 °C for 6 h. The stirring rate was 500 rpm. After cooling to room temperature, the cooled slurry was centrifuged. The obtained filter cake was washed with deionized water and centrifuged three times, and then dried at 70 °C for 12 h. After drying, the finished catalyst was obtained.

[0076] Example 7 A preparation method of ethanolamine, the specific steps are as follows:

[0077] S1. Mix 0.1 g of Cr / ZSM-5 catalyst with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. Add the resulting mixture to a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the rotation speed to 1000 rpm, adjust the reaction temperature to 60 °C, react for 15 h, analyze the solution composition by high-performance liquid chromatography, and calculate the conversion rate and selectivity. The specific results are shown in Table 7-1;

[0078] S2. Mix the glycolaldehyde mixture in S1 with ammonia water with a concentration of 1 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water is 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde is reductively aminated to ethanolamine at room temperature to obtain a glycolaldehyde mixture, and the product is analyzed by high-performance liquid chromatography. The specific results are shown in Table 7-2.

[0079] Table 7-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Cr / ZSM-5 catalyst

[0080] Table 7-2. Reductive amination reaction results of the reaction solution at room temperature

[0081]

[0082] The preparation method of the Cr / ZSM-5 catalyst is as follows:

[0083] Dissolve cadmium nitrate in deionized water to obtain a precursor aqueous solution with a Cr concentration of 1.0×10 -3 g / mL. Add 20 mL of the impregnation solution to 1 g of the carrier ZSM-5, stir evenly at 30 °C for 12 h, dry in an oven at 70 °C for 12 h, grind the obtained catalyst until there are no obvious particles, and then calcine at 500 °C for 9 h and cool to room temperature; in a 30% H 2 / Ar atmosphere, the calcined catalyst is reduced at 400 °C for 10 h and cooled to room temperature. Then add it to 25 mL of a 5% glycolic acid solution by mass, stir evenly at 90 °C for 6 h, and the stirring rate is 500 rpm. Cool to room temperature, centrifuge the cooled slurry, wash the centrifuged filter cake three times with deionized water and then dry at 70 °C for 12 h. After drying, the finished catalyst is obtained.

[0084] Example 8 A preparation method of ethanolamine, the specific steps are as follows:

[0085] S1. Mix 0.1 g of Au / Al 2 O 3The catalyst was mixed with 15 mL of an aqueous ethylene glycol solution with a concentration of 1 mol / L. The resulting mixture was added to a 25 mL high-pressure reactor, and oxygen was filled to 1 MPa. The rotation speed was adjusted to 1000 rpm, the reaction temperature was adjusted to 70 °C, and the reaction was carried out for 15 h. The composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 8-1;

[0086] S2. The glycolaldehyde mixture in S1 was mixed with ammonia water with a concentration of 1 mol / L. The volume ratio of the glycolaldehyde mixture to ammonia water was 1:1. Then, in an atmosphere with a hydrogen pressure of 4 MPa, glycolaldehyde was reductively aminated to ethanolamine at room temperature to obtain a glycolaldehyde mixture, and the product was analyzed by high-performance liquid chromatography. The specific results are shown in Table 8-2.

[0087] Table 8-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Au / Al 2 O 3 catalyst

[0088] Table 8-2. Reductive amination reaction results of the reaction solution at room temperature

[0089]

[0090] The preparation method of the Au / Al 2 O 3 catalyst is as follows:

[0091] Chloroauric acid was dissolved in deionized water to obtain a precursor aqueous solution with a Au concentration of 1.0×10 -3 g / mL. 20 mL of the impregnation solution was added to 1 g of the carrier Al 2 O 3 . After stirring evenly at 50 °C for 12 h, it was impregnated for 12 h, dried in an oven at 70 °C for 12 h. The obtained catalyst was ground until there were no obvious particles, and then calcined at 600 °C for 9 h and cooled to room temperature; in a 30% H 2 / Ar atmosphere, the calcined catalyst was reduced at 500 °C for 9 h and cooled to room temperature. Then it was added to 25 mL of a 5% citric acid solution by mass, and stirred evenly at 90 °C for 6 h at a stirring rate of 500 rpm, and cooled to room temperature. The cooled slurry was centrifuged, and the obtained filter cake was washed with deionized water and centrifuged three times and then dried at 70 °C for 12 h. After drying, the finished catalyst was obtained.

[0092] Comparative Example 1

[0093] With the molar ratio of liquid ammonia to ethylene glycol being 15:1 and the molar ratio of hydrogen to ethylene glycol being 0.1:1, 24.8 g (0.4 mo1) of ethylene glycol and 1 g of Co / Al 2 O 3 were added into a 200 mL batch high-pressure reactor. After purging with nitrogen three times, hydrogen was charged into the batch high-pressure reactor to 0.5 MPa, and then 102 g (6 mol) of liquid ammonia was pumped into the above system using a metering pump. The temperature was raised to 250 °C, and the pressure in the reactor was adjusted to 8 MPa with nitrogen. After reacting for 3 h, it was cooled and sampled for analysis. The conversion rate of ethylene glycol was 58%, and the yield of ethanolamine was 38%.

[0094] The Co / Al 2 O 3 catalyst was the same as that in Example 1.

[0095] Comparative Example 2

[0096] With the molar ratio of liquid ammonia to ethylene glycol being 13:1, 10 mL of mordenite was filled into a fixed-bed reactor with an inner diameter of 8 mm for the reaction tube, and the space velocity of ethylene glycol was 0.3 h -1 . The hydrogen pressure was 15 MPa. The ammoniation reaction temperature was 330 °C. The conversion rate of ethylene glycol reached 54%. Sampling and analysis were carried out, and the selectivity of ethanolamine reached 40.2%, and the selectivity of ethylenediamine was 26.4%.

[0097] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing ethanolamine, characterized in that: The following steps are involved: Firstly, the catalyst is mixed with an ethylene glycol aqueous solution and then subjected to an oxidation reaction in an oxygen atmosphere to obtain a glycolaldehyde mixed solution, and then the glycolaldehyde mixed solution is mixed with an ammonia solution and subjected to a reduction amination reaction to obtain ethanolamine; The catalyst is one of Co / Al2O3, Pd / NaY, Ag / C, Fe / SiO2, and Cr / ZSM-5; The catalyst is prepared by an impregnation method, and the main steps of preparing the catalyst by the impregnation method include: preparing a metal salt solution containing active components at a required concentration, impregnating the metal salt solution into a carrier or an intermediate catalyst at 30° C. to 60° C., and then drying, calcining, and cooling; The catalyst is subjected to reduction activation treatment before use, and the reduction activation treatment includes: heat treating the catalyst at 400°C to 600°C in a 30% H2 / Ar atmosphere for 7 to 10 h, then cooling to room temperature and adding an acid solution, stirring at 90°C for 6 h, cooling, centrifuging, washing, and drying.

2. The preparation method according to claim 1, characterized in that: The mass volume ratio of the catalyst to the ethylene glycol aqueous solution is 1 g: (100~200) mL.

3. The preparation method according to claim 1, characterized in that: The concentration of the ethylene glycol aqueous solution is 0.1-5 mol / L.

4. The preparation method according to claim 1, characterized in that: The ethylene glycol oxidation reaction temperature is 50° C. to 80° C., the reaction time is 2.5 to 25 h, and the reaction is carried out under stirring conditions at a rotation speed of 1000 rpm.

5. The preparation method according to claim 1, characterized in that: The reductive amination is carried out in a hydrogen atmosphere, the hydrogen pressure is 3.0-5.0 MPa, the reaction temperature is room temperature, and the reaction time is 2.5-25 h.

6. The preparation method according to claim 1, characterized in that: The concentration of the ammonia water is 0.1-5 mol / L, and the volume ratio of the ethanolaldehyde mixed solution to the ammonia water is 1:1.

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