Preparation method of ethanolamine

Abstract

The invention provides a preparation method of ethanolamine, and relates to the technical field of preparation of ethanolamine. The method comprises the following steps: firstly, promoting oxidation of ethylene glycol by using a catalyst to obtain a glycolaldehyde mixed solution, then mixing the glycolaldehyde mixed solution with ammonia water, and carrying out reductive amination to obtain ethanolamine. The synthesis process is mild in reaction condition and free of generation of toxic by-products, the ethylene glycol conversion rate in the reaction process is as high as 80%, the ethanolamine selectivity is as high as 60%, and the method is an efficient, economical and easy-to-scale-production ethanolamine green preparation method and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of ethanolamine, and in particular 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, pesticide, etc. In the traditional ethanolamine synthesis process, ethanolamine is mainly prepared by the addition reaction of ethylene oxide and ammonia. 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.

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

[0004] The invention patent with publication number CN103664649A discloses a method for preparing monoethanolamine from ethylene glycol, wherein the reaction system is composed of ethylene glycol, liquid ammonia, and hydrogen, and the catalyst is one or more of alumina, silicon dioxide, activated carbon, and molecular sieve as carriers, and at least two of active components Ru, Ni, Pd, Pt, Co, Mo, Fe, Mn, Sn, Zn, and B are loaded, and ethylene glycol and liquid ammonia can be converted into monoethanolamine with high activity and selectivity under the action of the catalyst, and ethylenediamine, piperazine, etc. are co-produced, and the method is simple to operate and has a high yield of monoethanolamine. However, the method requires loading at least two active components to prepare the catalyst, which increases the catalyst cost and has a low ethylene glycol conversion rate.

[0005] Therefore, it is necessary to develop a green preparation method for ethanolamine that is efficient, economical and easy to scale up, so as to increase 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, which uses ethylene glycol as a raw material and obtains ethanolamine through a two-step reaction. The reaction conditions are mild, no toxic by-products are generated, and the raw material conversion rate and product selectivity are high. The method is an efficient, economical and easy to scale green method for preparing ethanolamine.

[0007] The method for preparing ethanolamine of the present invention comprises the following steps: Firstly, a catalyst is used to promote the oxidation of ethylene glycol to obtain a glycolaldehyde mixed solution, and then the glycolaldehyde mixed solution is mixed with ammonia water and then reduced and aminated to obtain ethanolamine.

[0008] Preferably, the catalyst is a supported single metal catalyst, including a carrier and an active component, the carrier is at least one of metal oxide, molecular sieve, and activated carbon; the metal oxide is at least one of Al2O3, SiO2, and TiO2, the molecular sieve is NaY and / or ZSM-5; the active component is Co, Fe, Al, Cr, Au, Ag, Ru or Pd.

[0009] Preferably, the catalyst is prepared by an impregnation method.

[0010] Preferably, the catalyst is subjected to reduction activation treatment during use, and the main steps of the reduction activation treatment include: heat treating the catalyst in a 30% H2 / Ar atmosphere, then cooling to room temperature and adding an acid solution, stirring at a certain temperature for a period of time, then cooling, centrifuging, washing, and drying.

[0011] Preferably, the ethylene glycol oxidation 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 at a rotation speed of 1000 rpm.

[0012] Preferably, the reductive amination is carried out in a hydrogen atmosphere with a hydrogen pressure of 3.0-5.0 MPa; the concentration of the aqueous ammonia is 0.1-5 mol / L; the volume ratio of the ethanolaldehyde mixed solution to the aqueous ammonia is 1:1; the reaction temperature is room temperature, and the reaction time is 2.5-25 h.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are: The invention performs reductive amination under mild conditions to generate the target product ethanolamine. The synthetic process has mild reaction conditions and no toxic byproducts are generated. During the reaction, the ethylene glycol conversion rate is as high as 80%, and the ethanolamine selectivity is as high as 60%. The invention is an efficient, economical and easy-to-scale green preparation method for ethanolamine, and has broad application prospects. DETAILED DESCRIPTION

[0014] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] The present invention provides a method for preparing ethanolamine, comprising the following steps: Firstly, a catalyst is used to promote the oxidation of ethylene glycol to obtain a glycolaldehyde mixed solution, and then the glycolaldehyde mixed solution is mixed with ammonia water and then reduced and aminated to obtain ethanolamine.

[0016] The ethanolamine preparation process of the present invention is divided into two steps. The first step is to oxidize ethylene glycol to prepare ethanolaldehyde. In the reaction process, the present invention promotes the oxidation of ethylene glycol by using a specific catalyst, thereby significantly improving the conversion rate of ethylene glycol. Under the conditions specified in the present invention, the conversion rate of ethylene glycol can reach more than 80%, which is significantly improved compared with the prior art.

[0017] In some specific embodiments of the present invention, the catalyst is a supported monometallic catalyst, which includes a carrier and an active component, wherein the carrier is at least one of metal oxide, molecular sieve, and activated carbon; the metal oxide is at least one of Al2O3, SiO2, and TiO2; the molecular sieve is NaY and / or ZSM-5; and the active component is Co, Fe, Al, Cr, Au, Ag, Ru, or Pd. The monometallic catalyst of the present invention utilizes the synergistic effect between the active component and the carrier to improve the conversion rate of ethylene glycol, and provides better activity, selectivity, and stability for subsequent reductive amination.

[0018] The supported catalyst of the present invention is prepared by an impregnation method, which can be carried out in one step or in multiple steps. The main steps of preparing the catalyst by the impregnation method include: preparing a metal salt solution containing an active component at a desired concentration, impregnating 20 mL of the metal salt solution into 1 g of a carrier or intermediate catalyst at a certain temperature, and then drying, calcining, and cooling. 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℃~60℃, the impregnation time is 8~16 h, and the preferred impregnation time is 12 h; the drying and calcination are carried out in an air atmosphere, the drying temperature is 40℃~70℃, and the drying time is at least 12 h; the calcination temperature is 500℃~600℃, and the calcination time is 8~9 h.

[0019] The catalyst of the present invention needs to be reduced and activated before use, and the main steps of the reduction and activation include: heat treating the catalyst in a 30% H2 / Ar atmosphere, then cooling to room temperature and adding an acid solution, stirring at a certain temperature for a period of time, cooling, centrifuging, washing, and drying. Wherein, the acid solution is a citric acid solution, an ethanolic acid solution, an oxalic acid solution, a propionic acid solution, and a lactic acid solution, and the concentration of the acid solution is 5wt%; the heat treatment temperature is 400℃~600℃, and the heat treatment time is 7~10h; the stirring temperature is 90℃, the stirring time is 6h, and the stirring rate is 300~500 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℃, and the drying time is at least 12h.

[0020] The first step of the present invention is to oxidize ethylene glycol to prepare ethanolaldehyde, and the main steps include: mixing the catalyst with the ethylene glycol aqueous solution and then performing an oxidation reaction in an oxygen atmosphere to obtain an ethanolaldehyde mixed solution. 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-80°C, preferably the reaction temperature is 60°C-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.

[0021] The second step of the present invention is to prepare ethanolamine by reductive amination, which mainly comprises: mixing the ethanolaldehyde mixed solution with ammonia water, and reductive amination in a hydrogen atmosphere to obtain ethanolamine. The concentration of the ammonia water is 0.1-5 mol / L, preferably 1-2 mol / L; the volume ratio of the ethanolaldehyde mixed solution to the 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.

[0022] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0023] Unless otherwise specified, all experiments were repeated 3 times and the results were expressed as mean values.

[0024] Example 1 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g of Co / Al2O3 catalyst with 15 mL of 1 mol / L ethylene glycol aqueous solution, add the obtained mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 70°C, react for 15 h, and obtain an ethanolaldehyde mixed solution. Analyze the solution components by high performance liquid chromatography, calculate the conversion rate and selectivity, and the specific results are shown in Table 1-1; S2. The ethanolaldehyde mixture in S1 was mixed with 1 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixture to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde was reductively aminated at room temperature to generate ethanolamine. The product was analyzed by high performance liquid chromatography. The specific results are shown in Table 1-2.

[0025] Table 1-1. Results of selective oxidation of 1 mol / L ethylene glycol solution over Co / Al2O3 catalyst

[0026] Table 1-2. Reductive amination reaction results of the reaction solution at room temperature

[0027] The preparation method of the Co / Al2O3 catalyst is as follows: Dissolve cobalt nitrate in deionized water to obtain a Co concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of the carrier Al2O3, and the mixture was thoroughly and evenly stirred at 50°C for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 400°C for 7 h, cooled to room temperature, and then added to 25 mL of 5% mass fraction citric acid solution, and thoroughly and evenly stirred at 90°C for 6 h with a stirring rate of 500 rpm, cooled to room temperature, and 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.

[0028] Example 2 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g of Pd / NaY catalyst with 15 mL of 1 mol / L ethylene glycol aqueous solution, add the obtained mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 60°C, react for 15 h, and obtain an ethanolaldehyde mixed solution. Analyze the solution components by high performance liquid chromatography, calculate the conversion rate and selectivity, and the specific results are shown in Table 2-1; S2. Mix the ethanolaldehyde mixture in S1 with 2 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixture to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine. The product analysis is performed by high performance liquid chromatography. The specific results are shown in Table 2-2.

[0029] Table 2-1. Results of selective oxidation of 1 mol / L ethylene glycol solution catalyzed by Pd / NaY catalyst

[0030] Table 2-2. Reductive amination reaction results of the reaction solution at room temperature

[0031] The preparation method of the Pd / NaY catalyst is as follows: Dissolve chloropalladium in deionized water to obtain a Pd concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of carrier NaY, and the mixture was thoroughly and evenly stirred at 60°C for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 400°C for 8 h, cooled to room temperature, and then added to 25 mL of 5% ethanolic acid solution, and thoroughly and evenly stirred at 90°C for 6 h at a stirring rate of 500 rpm. The mixture was cooled to room temperature, and 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.

[0032] Example 3 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g Au / TiO2 catalyst with 15 mL 2 mol / L ethylene glycol aqueous solution, add the resulting mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 70°C, react for 20 h, analyze the solution components by HPLC, calculate the conversion rate and selectivity, and see Table 3-1 for specific results; S2. Mix the ethanolaldehyde mixed liquid in S1 with 2 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixed liquid to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine to obtain an ethanolaldehyde mixed liquid. The product is analyzed by high performance liquid chromatography. The specific results are shown in Table 3-2.

[0033] Table 3-1. Results of selective oxidation reaction of 1 mol / L ethylene glycol solution catalyzed by Au / TiO2 catalyst

[0034] Table 3-2. Reductive amination reaction results of the reaction solution at room temperature

[0035] The preparation method of the Au / TiO2 catalyst is as follows: Take chloroauric acid and dissolve it in deionized water to obtain an Au concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of the carrier TiO2, and the mixture was thoroughly and evenly stirred at 50°C for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 500°C for 8 h, cooled to room temperature, and then added to 25 mL of 5% oxalic acid solution, and thoroughly and evenly stirred at 90°C for 6 h at a stirring rate of 500 rpm, cooled to room temperature, and 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 4 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g of Ru / TiO2 catalyst with 15 mL of 1 mol / L ethylene glycol aqueous solution, add the resulting mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 70°C, react for 15 h, analyze the solution components by HPLC, calculate the conversion rate and selectivity, and see Table 4-1 for specific results; S2. Mix the ethanolaldehyde mixed liquid in S1 with 2 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixed liquid to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine to obtain an ethanolaldehyde mixed liquid. The product is analyzed by high performance liquid chromatography. The specific results are shown in Table 4-2.

[0037] Table 4-1. Selective oxidation reaction results of 1 mol / L ethylene glycol solution catalyzed by Ru / TiO2 catalyst

[0038] Table 4-2. Results of reductive amination reaction of the reaction solution at room temperature

[0039] The preparation method of the Ru / TiO2 catalyst is as follows: Take ruthenium chloride and dissolve it in deionized water to obtain a concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of the carrier TiO2, and the mixture was thoroughly and evenly stirred at 60°C for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 400°C for 9 h, cooled to room temperature, and then added to 25 mL of 5% propionic acid solution, and thoroughly and evenly stirred at 90°C for 6 h at a stirring rate of 500 rpm, cooled to room temperature, and 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.

[0040] Example 5 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g of Ag / C catalyst with 15 mL of 1 mol / L ethylene glycol aqueous solution, add the obtained mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 70°C, react for 20 h, and obtain an ethanolaldehyde mixed solution. Analyze the solution components by high performance liquid chromatography, calculate the conversion rate and selectivity, and the specific results are shown in Table 5-1; S2. Mix the ethanolaldehyde mixture in S1 with 1 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixture to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine. The product analysis is performed by high performance liquid chromatography. The specific results are shown in Table 5-2.

[0041] Table 5-1. Results of selective oxidation reaction of 1 mol / L ethylene glycol solution catalyzed by Au / C catalyst

[0042] Table 5-2. Reductive amination reaction results of the reaction solution at room temperature

[0043] The preparation method of the Ag / C catalyst is as follows: Take silver chloride and dissolve it in deionized water to obtain an Ag concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of the carrier activated carbon, and the mixture was fully and evenly stirred at 70°C for 12 h, and then dried in an oven at 40°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% H2 / Ar atmosphere, the calcined catalyst was reduced at 400°C for 8 h, cooled to room temperature, and then added to 25 mL of 5% mass fraction citric acid solution, and fully and evenly stirred at 90°C for 6 h with a stirring rate of 500 rpm, cooled to room temperature, and 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.

[0044] Example 6 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g Fe / SiO2 catalyst with 15 mL 1 mol / L ethylene glycol aqueous solution, add the resulting mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 70°C, react for 15 h, analyze the solution components by HPLC, calculate the conversion rate and selectivity, and see Table 6-1 for specific results; S2. Mix the ethanolaldehyde mixed liquid in S1 with 1 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixed liquid to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine to obtain an ethanolaldehyde mixed liquid. The product is analyzed by high performance liquid chromatography. The specific results are shown in Table 6-2.

[0045] Table 6-1. Results of selective oxidation of 1 mol / L ethylene glycol solution catalyzed by Fe / SiO2 catalyst

[0046] Table 6-2. Results of reductive amination reaction of the reaction solution at room temperature

[0047] The preparation method of the Fe / SiO2 catalyst is as follows: Take ferric nitrate and dissolve it in deionized water to obtain an Ag concentration of 2.5×10 -4 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of carrier SiO2, and the mixture was thoroughly and evenly stirred at 50°C for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 600°C for 9 h, cooled to room temperature, and then added to 25 mL of 5% lactic acid solution, and thoroughly and evenly stirred at 90°C for 6 h at a stirring rate of 500 rpm. The mixture was cooled to room temperature, and 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.

[0048] Example 7 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g of Cr / ZSM-5 catalyst with 15 mL of 1 mol / L ethylene glycol aqueous solution, add the resulting mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 60°C, react for 15 h, analyze the solution components by HPLC, calculate the conversion rate and selectivity, and see Table 7-1 for specific results; S2. Mix the ethanolaldehyde mixed liquid in S1 with 1 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixed liquid to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine to obtain an ethanolaldehyde mixed liquid. The product is analyzed by high performance liquid chromatography. The specific results are shown in Table 7-2.

[0049] Table 7-1. Results of selective oxidation of 1 mol / L ethylene glycol solution over Cr / ZSM-5 catalyst

[0050] Table 7-2. Reductive amination reaction results of the reaction solution at room temperature

[0051] The preparation method of the Cr / ZSM-5 catalyst is as follows: Dissolve cadmium nitrate in deionized water to obtain a Cr concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of the carrier ZSM-5, and the mixture was fully and evenly stirred at 30°C and impregnated for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 400°C for 10 h, cooled to room temperature, and then added to 25 mL of 5% ethanolic acid solution, and fully and evenly stirred at 90°C for 6 h at a stirring rate of 500 rpm. The mixture was cooled to room temperature, and 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.

[0052] Example 8 A method for preparing ethanolamine, the specific steps are as follows: S1. Mix 0.1 g Au / Al2O3 catalyst with 15 mL 1 mol / L ethylene glycol aqueous solution, add the resulting mixture into a 25 mL high-pressure reactor, fill with oxygen to 1 MPa, adjust the speed to 1000 rpm, adjust the reaction temperature to 70°C, react for 15 h, analyze the solution components by HPLC, calculate the conversion rate and selectivity, and see Table 8-1 for specific results; S2. Mix the ethanolaldehyde mixed liquid in S1 with 1 mol / L ammonia water, the volume ratio of the ethanolaldehyde mixed liquid to the ammonia water being 1:1. Then, in an atmosphere of 4 MPa hydrogen pressure, ethanolaldehyde is reductively aminated at room temperature to generate ethanolamine to obtain an ethanolaldehyde mixed liquid. The product is analyzed by high performance liquid chromatography. The specific results are shown in Table 8-2.

[0053] Table 8-1. Results of selective oxidation reaction of 1 mol / L ethylene glycol solution catalyzed by Au / Al2O3 catalyst

[0054] Table 8-2. Results of reductive amination reaction of the reaction solution at room temperature

[0055] The preparation method of the Au / Al2O3 catalyst is as follows: Take chloroauric acid and dissolve it in deionized water to obtain an Au concentration of 1.0×10 -3 g / mL precursor aqueous solution, 20 mL of the impregnation solution was added to 1 g of the carrier Al2O3, and the mixture was thoroughly and evenly stirred at 50°C for 12 h, and then 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% H2 / Ar atmosphere, the calcined catalyst was reduced at 500°C for 9 h, cooled to room temperature, and then added to 25 mL of 5% citric acid solution, and thoroughly and evenly stirred at 90°C for 6 h at a stirring rate of 500 rpm. The mixture was cooled to room temperature, and 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.

[0056] Comparative Example 1 According to the molar ratio of liquid ammonia to ethylene glycol of 15:1 and the molar ratio of hydrogen to ethylene glycol of 0.1:1, 24.8 g (0.4 mol) of ethylene glycol and 1 g of Co / Al2O3 were added to a 200 mL intermittent high-pressure reactor. After nitrogen was filled and ventilated three times, hydrogen was filled into the intermittent high-pressure reactor to 0.5 MPa, and then 102 g (6 mol) of liquid ammonia was pumped into the above system with 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, the reaction was cooled, sampled, and analyzed. The conversion rate of ethylene glycol was 58%, and the yield of ethanolamine was 38%.

[0057] The Co / Al2O3 catalyst is the same as that in Example 1.

[0058] Comparative Example 2 The molar ratio of liquid ammonia to ethylene glycol was 13:1, and 10 mL of mordenite was filled into a fixed bed reactor with an inner diameter of 8 mm. The ethylene glycol hourly velocity was 0.3 h -1 , hydrogen pressure 15 MPa. The amination reaction temperature was 330°C, the ethylene glycol conversion rate reached 54%, sampling and analysis showed that the ethanolamine selectivity reached 40.2%, and the ethylenediamine selectivity was 26.4%.

[0059] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing ethanolamine, characterized in that: The following steps are involved: Firstly, a catalyst is used to promote the oxidation of ethylene glycol to obtain a glycolaldehyde mixed solution, and then the glycolaldehyde mixed solution is mixed with ammonia water and subjected to reduction amination to obtain ethanolamine; The catalyst comprises a carrier and an active component, wherein the carrier is at least one of a metal oxide, a molecular sieve, and activated carbon; and the active component is Co, Fe, Cr, Au, Ag, Ru, or Pd; The metal oxide is at least one of Al2O3, SiO2, and TiO2, and the molecular sieve is NaY and / or ZSM-5.

2. The preparation method according to claim 1, characterized in that: 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, roasting, and cooling.

3. The preparation method according to claim 1, characterized in that: The catalyst is subjected to reduction activation treatment before use, and the reduction activation treatment includes: heat treating the catalyst in a 30% H2 / Ar atmosphere, then cooling to room temperature and adding an acid solution, stirring at 90°C for 6 hours, cooling, centrifuging, washing, and drying.

4. 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.

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

6. 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.

7. 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.

8. 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.

Images