Method for synthesizing diol by utilizing erythritol

Abstract

The invention discloses a method for high-yield synthesis of diol by using erythritol, which comprises the following steps: mixing erythritol, a magnetic catalyst and deionized water, and reacting in a sealed manner in a hydrogen atmosphere to prepare glycol products such as ethylene glycol, 1, 2-propylene glycol, 1, 2-butanediol, 2, 3-butanediol and 1, 3-butanediol, and butanediol is used as a main product (up to 70.9%). According to the method disclosed by the invention, various glycols with high added values can be synthesized, the yield is high, and meanwhile, the used magnetic catalyst can be used for next reaction after being magnetically separated and washed with clear water, so that the problem of recycling of the catalyst in the use process can be solved.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and specifically relates to a method for synthesizing diols by utilizing erythritol, and more specifically to a method for synthesizing diols by utilizing erythritol by utilizing a magnetic non-precious metal catalyst. Background Art

[0002] Diols (ethylene glycol, propylene glycol and butanediol) are multifunctional and high-value platform chemicals, and are also important intermediates in the chemical industry. They are widely used and have a large market demand. Among them, ethylene glycol is used as the main raw material for the production of organic products such as polyester, polyester resin, synthetic fibers, plasticizers and surfactants. At present, the production route of ethylene glycol mainly uses ethylene as raw material and produces ethylene glycol through ethylene oxide. In addition, there is a coal chemical route that uses coal or natural gas as raw materials, first produces synthesis gas (CO+H2), and then produces ethylene glycol through direct or indirect methods. Propylene glycol is widely used as a monomer in building materials, chemical and pharmaceutical industries, and is also used in the production of polyester resins, antifreeze, liquid detergents, cosmetics and food. At present, propylene glycol is mainly produced in industry through the selective oxidation of non-renewable petroleum-derived propylene to propylene oxide and its subsequent hydration process. Butanediol is commonly used as a solvent and raw material in various industries such as the pharmaceutical, cosmetics and polyester industries. Common butanediols include 1,2-butanediol, 1,3-butanediol and 2,3-butanediol. 1,2-Butanediol has the characteristics of low viscosity and low freezing point, so it is widely used in the synthesis of polyester polyols, plasticizers, cosmetics and pharmaceuticals (such as ethambutol, levetiracetam and brivaracetam). 1,2-Butanediol is also commonly used as a raw material for the production of polyester resins and plasticizers. It is a potential liquid fuel substitute for fossil fuels and a widely used chemical raw material and solvent. 1,3-Butanediol is used as an organic solvent for food flavoring and a raw material for polyurethane and polyester resins. 2,3-Butanediol is used in printing inks, perfumes, fumigants, etc. Butanediol is mainly produced in industry by the acetylene aldehyde method, maleic anhydride method, butadiene method and propylene oxide method. However, the reserves of fossil resources are limited and unsustainable. The limited reserves of chemical resources have stimulated the development of a sustainable chemical industry, and the synthesis of diols using renewable biomass as raw materials is an important direction of current research and development.

[0003] Erythritol is a C4 sugar alcohol derived from fruits and fermented foods. It is mainly produced by biochemical fermentation of glucose or glycerol. The conversion of erythritol into commercially valuable ethylene glycol, 1,2-propylene glycol, 1,2-butylene glycol, 2,3-butylene glycol and 1,3-butylene glycol is an environmentally friendly and sustainable production method. However, there are few studies on the synthesis of butanediol by hydrogenation of erythritol, which mainly focuses on the use of precious metal catalysts. However, the use of precious metal catalysts is less economical, increases costs, and often requires the use of 1,4-dioxane as a solvent, which is harmful to the environment and is not conducive to large-scale industrial production. Therefore, it is urgent to find catalysts that overcome the above shortcomings and are easy to recover for the catalytic conversion of erythritol to synthesize high-yield diols (ethylene glycol, 1,2-propylene glycol, especially 1,2-butylene glycol, 2,3-butylene glycol and 1,3-butylene glycol). Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for synthesizing diols with high yield by utilizing erythritol.

[0005] To achieve the above object, the present invention adopts the following technical solution: A method for synthesizing diols using erythritol comprises the following steps: placing erythritol, a magnetic catalyst and deionized water into a high-pressure reactor, reacting the reactor in a sealed manner under a hydrogen atmosphere, centrifuging the reaction mixture after cooling to room temperature, and taking a supernatant to obtain diols.

[0006] Furthermore, the preparation steps of the magnetic catalyst are as follows: dissolving the metal precursor in deionized water at room temperature, then adding nano-TiO2, and ultrasonicating for 10-40 minutes; subsequently, slowly adding a precipitant Na2CO3 solution under magnetic stirring to adjust the pH value of the mixed solution to 8, then continuously stirring and aging at 60-100°C for 1-5 hours, separating the precipitate by suction filtration, and thoroughly washing it with deionized water, and then drying the obtained precipitate at 90-140°C for 9-16 hours, cooling it to room temperature, fully grinding it, passing it through a 100-mesh sieve, and then calcining it at 300-500°C in an air atmosphere for 2-8 hours, and finally reducing it in a tubular furnace at 400-600°C in a hydrogen atmosphere for 2-10 hours to obtain the magnetic catalyst.

[0007] Furthermore, the metal precursor is at least one of nickel nitrate and cobalt nitrate.

[0008] Furthermore, the amounts of nano-TiO2 and metal precursor are converted according to the molar ratio of Ti to metal element of (1-7):(1-16).

[0009] Specifically, the magnetic catalyst is Ni@TiO2, Co@TiO2, or Ni-Co@TiO2.

[0010] When the magnetic catalyst is Ni@TiO2, the molar ratio of Ti to Ni is (2-6):(1-5).

[0011] When the magnetic catalyst is Co@TiO2, the molar ratio of Ti to Co is (2-6):(1-5).

[0012] When the magnetic catalyst is Ni-Co@TiO2, the molar ratio of Ti to Ni and Co is (1-7):(1-8):(1-8).

[0013] Furthermore, the mass ratio of deionized water to erythritol used is (0.5-2):(30-75).

[0014] Furthermore, the mass ratio of the magnetic catalyst to erythritol used is (0.5-2):(1-8).

[0015] Furthermore, the reaction conditions are: pressure 2-12 MPa, stirring speed 800 rpm, temperature 190-280° C., and time 2-10 h.

[0016] Furthermore, the obtained diols include ethylene glycol, 1,2-propylene glycol, 1,2-butanediol, 2,3-butanediol and 1,3-butanediol, among which butanediol is the main product, and its yield can reach up to 70.9%.

[0017] Furthermore, the precipitate after centrifugation can be directly used for the next operation after the magnetic catalyst is recovered by an external magnet and vacuum dried.

[0018] The beneficial effects of the present invention are: 1. The present invention uses a magnetic non-precious metal catalyst to catalyze the synthesis of diols from erythritol, which overcomes the problem that the traditional process requires the use of precious metals and toxic solvents.

[0019] 2. The magnetic non-precious metal catalyst used in the present invention is low-cost, has typical ferromagnetic behavior, has high magnetization intensity, and is extremely convenient and fast to recycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD patterns of Ni-Co (3:3), Co@TiO2 (3:4), Ni-Co@TiO2 (3:3:4), Ni-Co@TiO2 (4:3:4) and single Ni, Co, and TiO2 prepared in the examples.

[0021] Figure 2 The hysteresis regression line (a) and coercivity diagram (b) of Ni-Co (3:3), Co@TiO2 (3:4), and Ni-Co@TiO2 (3:3:4) prepared in the examples under an external magnetic field of 10 K. Figure 2 It can be seen that all samples have good hysteresis loop morphology, which belongs to the S-type hysteresis loop, and the curve shows superparamagnetism, so they can be easily recovered by an external magnet. DETAILED DESCRIPTION

[0022] A method for synthesizing diols using erythritol, comprising: placing erythritol, a magnetic catalyst and deionized water into a high-pressure reactor, sealing the reactor, exhausting the air, and injecting 2-12MPa H2, reacting at 190-280°C for 2-10h at a stirring rate of 800rpm, centrifuging the reaction mixture after cooling to room temperature, and taking the supernatant to obtain diols. The precipitate after centrifugation is recovered by an external magnet to recover the magnetic catalyst, and can be directly used for the next operation after vacuum drying.

[0023] The mass ratio of deionized water to erythritol is (0.5-2):(30-75). The mass ratio of magnetic catalyst to erythritol is (0.5-2):(1-8).

[0024] The magnetic catalyst is prepared by dissolving at least one of nickel nitrate and cobalt nitrate in deionized water at room temperature, then adding nano-TiO2 so that the molar ratio of Ti to the metal element is (1-7):(1-16), and ultrasonicating for 10-40 minutes; then, slowly dropping a precipitant Na2CO3 solution under magnetic stirring to adjust the pH value of the mixed solution to 8, then continuously stirring and aging at 60-100°C for 1-5 hours, separating the precipitate from the mixed solution by a suction filtration device, and thoroughly washing the obtained precipitate with deionized water, then drying the washed precipitate at 90-140°C for 9-16 hours, cooling to room temperature, fully grinding with a mortar and pestle, and then passing through a 100-mesh sieve, and then calcining at 300-500°C in an air atmosphere for 2-8 hours (heating rate of 5°C / min), and finally, placing the calcined product in a tubular furnace and reducing it at 400-600°C in a hydrogen atmosphere for 2-10 hours (heating rate of 2-10°C / min) to obtain the magnetic catalyst.

[0025] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0026] Preparation of Example Catalyst: 1. Preparation of Ni@TiO2 catalyst: 0.012 mol Ni(NO3)2·6H2O was dissolved in an appropriate amount of deionized water at room temperature, and then 0.016 mol nano-TiO2 was added and ultrasonicated for 20 min. Subsequently, under magnetic stirring, the precipitant Na2CO3 solution was slowly added dropwise, and the pH value of the mixed solution was adjusted to 8. After that, the mixed solution was continuously stirred and aged at 80°C for 3 h. The precipitate was separated from the mixed solution by a suction filtration device, and the obtained precipitate was thoroughly washed with deionized water. The washed precipitate was then dried at 120°C for 12 h, cooled to room temperature, and fully ground with a mortar and passed through a 100 mesh sieve. Then, it was calcined at 400°C in an air atmosphere for 4 h. Finally, the calcined product was placed in a tubular furnace and reduced at 500°C and 5% H2-N2 for 5 h. The prepared binary metal catalyst was recorded as Ni@TiO2 (3:4).

[0027] 2. Preparation of Co@TiO2 catalyst: Dissolve 0.012 mol Co(NO3)2·6H2O in an appropriate amount of deionized water at room temperature, add 0.016 mol nano-TiO2, and ultrasonicate for 20 min; the remaining steps are the same as those of Ni@TiO2 (3:4) catalyst, and the prepared binary metal catalyst is recorded as Co@TiO2 (3:4).

[0028] 3. Preparation of Ni-Co@TiO2 (x:y:z) catalyst: Dissolve 0.012 mol Ni(NO3)2·6H2O and 0.012 mol Co(NO3)2·6H2O in an appropriate amount of deionized water at room temperature, add 0.016 mol nano-TiO2, and ultrasonicate for 20 min; the rest of the preparation steps are the same as those of Ni-Co@TiO2 (3:3:4) catalyst, and the prepared catalyst is recorded as Ni-Co@TiO2 (3:3:4). Similarly, by changing the amount of raw materials, catalysts with different metal molar ratios were prepared and named Ni-Co@TiO2 (x:y:z) catalysts, where x:y:z represents the metal molar ratio of Ni, Co and Ti, specifically Ni-Co@TiO2 (4:3:4), Ni-Co@TiO2 (2:3:4), Ni-Co@TiO2 (3:4:4), Ni-Co@TiO2 (3:2:4), Ni-Co@TiO2 (3:3:5) and Ni-Co@TiO2 (3:3:3).

[0029] 4. Preparation of Ni-Co catalyst: Dissolve 0.012 mol Ni(NO3)2·6H2O and 0.012 mol Co(NO3)2·6H2O in an appropriate amount of deionized water at room temperature and ultrasonicate for 20 min; the remaining steps are the same as those of Ni@TiO2 (3:4) catalyst, and the prepared binary metal catalyst is recorded as Ni-Co (3:3).

[0030] 5. Single Ni or Co catalyst: Ni(NO3)2·6H2O or Co(NO3)2·6H2O was dried at 120℃ for 12 h and then directly calcined at 400℃ in air atmosphere for 4 h. The calcined product was reduced in a tube furnace at 500℃ and 5% H2-N2 by volume for 5 h. The prepared catalysts were marked as Ni or Co catalysts.

[0031] 6. TiO2 (used directly for catalytic reaction without any pretreatment).

[0032] Application Example 1 0.5g erythritol, 0.15g catalyst and 30g deionized water were placed in a high pressure reactor. After the reactor was sealed, the air in the reactor was replaced with nitrogen. After exhausting, 8MPa H2 was injected. The reaction was closed at 245°C for 5h at a stirring rate of 800rpm and then cooled to room temperature. After the reaction mixture was centrifuged, the supernatant was analyzed by liquid chromatography. The test results are listed in Table 1.

[0033] Table 1 Test results

[0034] From the results in Table 1, it can be seen that when the synthesis of diols was catalyzed by Ni or TiO2 alone, no diol was produced. When Co metal alone was used as a catalyst, the conversion rate of erythritol was 89.5%, and the total diol yield was 57.2%, but more 1,2,3-butanetriol was produced as a byproduct.

[0035] When using bimetallic catalysts, both Ni@TiO2 and Co@TiO2 can achieve good reaction results (total glycol yield is more than 69%), but when using NiCo as a catalyst, there is no reaction effect.

[0036] When the trimetallic catalyst Ni-Co@TiO2 is used for catalysis, compared with other ratios, when the metal molar ratio of Ni, Co, and Ti is 3:3:4, the total glycol yield can reach 83.1%, and the yield of butanediol can reach 70.9%, indicating that it has the best effect in synthesizing glycols.

[0037] Application Example 2 0.5g erythritol, 0.15g Ni-Co@TiO2 (3:3:4) catalyst and 30g deionized water were placed in a high-pressure reactor. After the reactor was sealed, the air in the reactor was replaced with nitrogen. After exhausting, 8MPa H2 was injected. The reaction was closed at 215-265℃ for 5h at a stirring rate of 800rpm and then cooled to room temperature. After the reaction mixture was centrifuged, the supernatant was analyzed by liquid chromatography. The test results are listed in Table 2.

[0038] Table 2 Test results

[0039] As shown in Table 2, temperature is crucial for the production of diols. Under low temperature (215-225℃), the conversion rate of erythritol and the yield of total diols are low (48.7~51.1% and 26.3~37.7%, respectively), and the yield of the intermediate 1,2,3-butanetriol is high (14.2~24.7%), indicating that low temperature conditions are not conducive to the conversion of erythritol into diols. As the temperature increases, the yield of total diols, especially butanediol, first increases and then decreases. At 245℃, although the conversion rate of erythritol is only 91.9%, the yield of total diols can reach 83.1%, and the yield of butanediol can reach 70.9%, indicating that its effect of synthesizing diols is the best.

[0040] Application Example 3 0.5g erythritol, 0.15g Ni-Co@TiO2 (3:3:4) catalyst and 30g deionized water were placed in a high-pressure reactor. After the reactor was sealed, the air in the reactor was replaced with nitrogen. After exhausting, 5-9MPa H2 was injected. The reaction was closed at 245℃ for 5h at a stirring rate of 800rpm and then cooled to room temperature. After the reaction mixture was centrifuged, the supernatant was analyzed by liquid chromatography. The test results are listed in Table 3.

[0041] Table 3 Test results

[0042] As shown in Table 3, as the pressure gradually increases, the yield of 1,2,3-butanetriol changes from more to less and then to more, indicating that in order to convert 1,2,3-butanetriol into butanediol, the pressure range needs to be appropriate. Therefore, when the pressure is 8MPa, the yield of total diols can reach 83.1%, and the yield of butanediol can reach 70.9%, and the effect of synthesizing diols is the best.

[0043] Application Example 4 0.5g erythritol, 0.15g Ni-Co@TiO2 (3:3:4) catalyst and 30g deionized water were placed in a high-pressure reactor. After the reactor was sealed, the air in the reactor was replaced with nitrogen. After exhausting, 8MPa H2 was injected. The reaction was closed at 245℃ for 4-8h at a stirring rate of 800rpm and then cooled to room temperature. After the reaction mixture was centrifuged, the supernatant was analyzed by liquid chromatography. The test results are listed in Table 4.

[0044] Table 4 Test results

[0045] As shown in Table 4, when the reaction time is less than 5 h, the conversion rate of erythritol (86.0%) and the yield of total diols (54.8%) are both low, and are accompanied by the large-scale generation of the intermediate product 1,2,3-butanetriol (1,2,3-butanetriol yield 21.1%). As the time increases to more than 7 h, the yield of total diols decreases slightly (from 83.1% to 70.8%). Therefore, when the reaction time is 5 h, the yield of total diols can reach 83.1%, and the yield of butanediol can reach 70.9%, and the effect of synthesizing diols is the best.

[0046] Application Example 5 0.5g erythritol, 0.1-0.25g Ni-Co@TiO2 (3:3:4) catalyst and 30g deionized water were placed in a high-pressure reactor. After the reactor was sealed, the air in the reactor was replaced with nitrogen. After exhausting, 5MPa H2 was injected. The reaction was closed at 245℃ for 5h at a stirring rate of 800rpm and then cooled to room temperature. After the reaction mixture was centrifuged, the supernatant was analyzed by liquid chromatography. The test results are listed in Table 5.

[0047] Table 5 Test results

[0048] As shown in Table 5, when the catalyst dosage increases from 0.15 g to 0.2 g, the yield of total glycols reaches 84.5%. When the catalyst dosage continues to increase, the yield of total glycols does not change significantly. When the catalyst dosage is 0.15 g, the yield of butanediol is 70.9%, reaching the maximum.

[0049] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for synthesizing glycols using erythritol, characterized in that: Erythritol, a magnetic catalyst and deionized water are placed in a high-pressure reactor, and reacted in a sealed manner under a hydrogen atmosphere. After cooling to room temperature, the supernatant is collected after centrifugation to obtain diol.

2. The method according to claim 1, characterized in that: The mass ratio of deionized water to erythritol used is (0.5-2):(30-75).

3. The method according to claim 1, characterized in that: The mass ratio of the magnetic catalyst to erythritol is (0.5-2):(1-8).

4. The method according to claim 1, characterized in that: The preparation steps of the magnetic catalyst are as follows: dissolving a metal precursor in deionized water at room temperature, then adding nano-TiO2, and ultrasonicating for 10-40 minutes; subsequently, slowly dropping a Na2CO3 solution under magnetic stirring to adjust the pH value of the mixed solution to 8, then continuously stirring and aging at 60-100° C. for 1-5 hours, separating the precipitate by suction filtration and thoroughly washing it with deionized water, then drying and fully grinding the obtained precipitate, calcining it at 300-500° C. in an air atmosphere for 2-8 hours, and finally reducing it in a tubular furnace at 400-600° C. in a hydrogen atmosphere for 2-10 hours.

5. The method according to claim 4, characterized in that: The metal precursor is at least one of nickel nitrate and cobalt nitrate.

6. The method according to claim 4, characterized in that: The amount of nano-TiO2 and metal precursor is converted according to the molar ratio of Ti to metal element (1-7): (1-16).

7. The method according to claim 1, characterized in that: The reaction conditions are: pressure 2-12 MPa, stirring speed 800 rpm, temperature 190-280° C., and time 2-10 h.

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