Method for preparing dimethyl furan-2, 5-dicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural

Abstract

The invention discloses a method for preparing dimethyl furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural, which is characterized in that nitrogen-doped carbon-loaded cobalt-based bimetallic is used as a photocatalyst, oxygen or pure oxygen in air is used as an oxygen source, and the dimethyl furandicarboxylate is efficiently prepared under illumination reaction conditions of normal temperature and normal pressure. The problems of low reaction efficiency, violent reaction conditions and the like in the prior art are solved, and the method has a good utilization prospect.

Description

Technical Field

[0001] The invention belongs to the field of organic photocatalytic synthesis, and specifically relates to a method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural. Background Art

[0002] Upgrading renewable and unique biomass-derived platform compounds into fuels and valuable chemicals can not only reduce our dependence on depleting non-renewable petroleum resources, but also pave an interesting path for the synthesis of new materials, especially dimethyl 2,5-furandicarboxylate, which can be prepared by oxidative esterification of 5-hydroxymethylfurfural. As a substitute for petroleum-based terephthalic acid, it is currently developing vigorously and is used in the production of various polymer materials. Currently, the oxidative esterification of the biomass-based platform molecule 5-hydroxymethylfurfural to prepare dimethyl 2,5-furandicarboxylate is the main route for the synthesis of dimethyl 2,5-furandicarboxylate. Most of these reactions are carried out in cobalt-based catalytic systems, and supported bimetallic catalysts have higher catalytic activity, bimetallic synergistic effects, selectivity, and abundant reactive sites compared with previously reported monometallic catalysts, becoming a hot research direction in the field of catalysis in recent years.

[0003] According to existing reports, only a few materials containing gold, platinum or cobalt have been successfully used in the oxidative esterification of 5-hydroxymethylfurfural, among which nitrogen-doped carbon-supported co-catalysts have attracted much attention due to their high accessibility and low cost. For example, in the presence of an external base (such as potassium carbonate), a combination of nitrogen-doped carbon-supported cobalt and a co-catalyst (such as ruthenium) can achieve a high yield of dimethyl 2,5-furandicarboxylate. However, the additional addition of a base during the oxidation process makes these reaction systems less environmentally friendly. Therefore, the development of a new catalyst is conducive to solving the current problems of low catalytic efficiency and poor environmental friendliness. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural.

[0005] The first object of the present invention is achieved in this way. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural is to use 5-hydroxymethylfurfural as a raw material, a nitrogen-doped carbon-loaded cobalt-based bimetal as a catalyst, a xenon lamp as a light source system in a low-grade alcohol solution, and an oxidation reaction under normal pressure using oxygen in the air or pure oxygen as an oxygen source to obtain the target product dimethyl 2,5-furandicarboxylate; the other metal in the nitrogen-doped carbon-loaded cobalt-based bimetal is iron, ruthenium, tantalum, platinum, silver, palladium, manganese, potassium, cerium, nickel or copper.

[0006] The specific operations are as follows: The 5-hydroxymethylfurfural and the lower alcohol solution are mixed and placed in a reaction container, a catalyst is added, and a xenon lamp is used as a light source to irradiate the reactor. At normal pressure, oxygen in the air or pure oxygen is used as an oxygen source to react to obtain the 2,5-furandicarboxylic acid diester compound. The reaction temperature is room temperature, the reaction time is 1-12 hours, and the concentration of 5-hydroxymethyl in the lower alcohol solvent is 8-800mM; The catalyst is a nitrogen-doped carbon-supported cobalt-based bimetallic catalyst, wherein the metal loading in the catalyst is 1-10wt%, the other active metal other than cobalt is iron, ruthenium, gold, platinum, silver, palladium, manganese, potassium, cerium, nickel or copper, and the molar ratio of cobalt to the other active metal is 1:0.01-0.5; The mass ratio of the amount of the above catalyst to the above 5-hydroxymethylfurfural is 0.1-1:1; In a preferred embodiment of the present invention, the lower alcohol solvent is methanol and ethanol.

[0007] In a preferred embodiment of the present invention, the bimetallic metal is iron, ruthenium, gold, nickel or copper.

[0008] In a preferred embodiment of the present invention, the molar ratio of the bimetallic is 1:0.1-0.2.

[0009] In a preferred embodiment of the present invention, the metal loading in the catalyst is 4.8 wt %. In a preferred embodiment of the present invention, the amount of the catalyst used is such that the mass ratio of the nitrogen-doped carbon-supported catalyst to the above-mentioned 5-hydroxymethylfurfural is 0.17:1.

[0010] In a preferred embodiment of the present invention, a xenon lamp is used as a light source to irradiate the reactor so that the photocatalyst has oxidation-reduction ability, thereby being able to oxidize and reduce 5-hydroxymethylfurfural.

[0011] In a preferred embodiment of the present invention, the reaction pressure is normal pressure.

[0012] In a preferred embodiment of the present invention, the reaction temperature is room temperature.

[0013] The beneficial effects of the present invention are as follows: visible light is used to drive the reaction, thereby achieving the goal and pursuit of green environmental protection; at the same time, oxygen in the air is used as an oxygen source, and high-purity dimethyl 2,5-furandicarboxylate is efficiently prepared at room temperature, thereby solving the problems of low reaction efficiency, low product yield, and insufficient environmental protection and greenness in the prior art, and having good application prospects. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0015] The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural is as follows: 5-hydroxymethylfurfural is used as a raw material, a nitrogen-doped carbon-loaded cobalt-based bimetal is used as a catalyst, a xenon lamp is used as a light source system in a low-grade alcohol solution, and oxygen in the air or pure oxygen is used as an oxygen source to carry out an oxidation reaction under normal pressure to obtain the target dimethyl 2,5-furandicarboxylate; the other metal in the nitrogen-doped carbon-loaded cobalt-based bimetal is iron, ruthenium, tantalum, platinum, silver, palladium, manganese, potassium, cerium, nickel or copper.

[0016] The molar ratio of cobalt to another metal in the nitrogen-doped carbon-supported cobalt-based bimetal is 1:(0.01-0.5).

[0017] The metal loading amount in the nitrogen-doped carbon-loaded cobalt-based bimetallic is 1-10wt%.

[0018] The mass ratio of the amount of the nitrogen-doped carbon-loaded cobalt-based bimetal to the raw material 5-hydroxymethylfurfural is (0.1~1):1.

[0019] The temperature of the oxidation reaction is room temperature.

[0020] The oxidation reaction time is 1 to 30 hours.

[0021] The concentration of the raw material 5-hydroxymethylfurfural in the low-grade alcohol solvent is 8-800 mM.

[0022] The lower alcohol is methanol, ethanol, propanol or butanol.

[0023] The present invention is further described below with specific implementation cases: The preparation process of the catalyst used in the following examples refers to the paper published by Xiong Yu et al. (Advanced Materials 32.34 (2020): 2000896). The specific steps are as follows: First, weigh dicyandiamide, cobalt nitrate and another active metal nitrate respectively and put them into a polytetrafluoroethylene beaker, then add water and formaldehyde solution, and then put the beaker into an oil bath at 105°C and stir until the water evaporates. After drying, the precursor is obtained, and finally the precursor is calcined under an argon atmosphere to obtain a cobalt-based bimetallic catalyst containing different ratios of nitrogen-doped carbon materials, marked as Co x M y -NC, wherein M represents the type of the second metal, and x and y represent the ratio of Co to the second metal.

[0024] Embodiment 1-11 0.005 g of 5-hydroxymethylfurfural and 5 g of methanol (8 mM) were added to a 50 mL photocatalyst reactor, and then 0.03 g of Co4Fe1-NC, Co4Mn1-NC, Co4Cu1-NC, Co4Ag1-NC, Co4Ru1-NC, Co4Ni1-NC, Co4Pd1-NC, Co4Au1-NC, Co4Pt1-NC, Co4K1-NC or Co4Ce1-NC (wherein the metal loading was 4.8 wt % and the molar ratio of the two metals was 4:1) was added as a catalyst, the reaction solution was irradiated with a xenon lamp and stirred vigorously (600 rpm), condensed water was introduced into the reactor and the temperature was maintained at room temperature for 5 hours, and samples were taken after the reaction, and qualitative and quantitative detection was performed using GC-MS (Shimadzu) and GC (Agilent). The detection results are listed in Table 1 with serial numbers 1-11.

[0025] Examples 12-15 0.005 g of 5-hydroxymethylfurfural and 5 g of methanol (8 mM) were added to a 50 mL photocatalytic reactor, and then 0.03 g of Co4Fe1-NC, Co3Fe2-NC, Co2Fe3-NC, and Co1Fe1-NC (wherein the metal loading was 4.8 wt %, and the molar ratios of the two metals were 4:1, 3:2, 2:3, and 1:1, respectively) were added as catalysts. The reaction solution was irradiated with a xenon lamp and stirred vigorously (600 rpm). Condensed water was introduced into the reactor and the temperature was maintained at room temperature for 5 hours. After the reaction, samples were taken and qualitative and quantitative tests were performed using GC-MS (Shimadzu) and GC (Agilent). The test results are listed in Table 1 as serial numbers 12-15.

[0026] Examples 16-18 To a 50 mL photocatalytic reactor, 0.05 g, 0.25 g and 0.5 g of 5-hydroxymethylfurfural and 5 g of methanol (substrate concentrations were 80 mM, 400 mM and 800 mM, respectively) were added, and then 0.1 g, 0.5 g and 1 g of Co4Fe1-NC (wherein the metal loading was 4.8 wt % and the molar ratio of the two metals was 4:1) were added as catalysts, atmospheric pressure oxygen was introduced as an oxygen source, the reaction solution was irradiated with a xenon lamp, and vigorously stirred (600 rpm). Condensed water was introduced into the reactor and the temperature was maintained at room temperature for 10, 20 and 30 hours, respectively. After the reaction, samples were taken and qualitative and quantitative tests were performed using GC-MS (Shimadzu) and GC (Agilent). The test results are listed in Table 1 as serial numbers 16-18.

[0027] Examples 19-20 0.005 g of 5-hydroxymethylfurfural was added to a 50 mL photocatalytic reactor, followed by 5 g of ethanol or propanol (8 mM), and then 0.03 g of Co4Fe1-NC (wherein the metal loading was 4.8 wt % and the molar ratio of the two metals was 4:1) as a catalyst. The reaction solution was irradiated with a xenon lamp and stirred vigorously (600 rpm). Condensed water was introduced into the reactor and the temperature was maintained at room temperature for 6 hours. After the reaction, samples were taken and qualitative and quantitative tests were performed using GC-MS (Shimadzu) and GC (Agilent). The test results are listed in Tables 2 and 3.

[0028] Examples 21-22 0.005 g of 5-hydroxymethylfurfural was added to a 50 mL photocatalytic reactor, followed by 5 g of methanol (8 mM), and then 0.01 g and 0.02 g of Co4Fe1-NC (wherein the metal loading was 4.8 wt % and the molar ratio of the two metals was 4:1) were added as catalysts, respectively. The reaction solution was irradiated with a xenon lamp and stirred vigorously (600 rpm). Condensed water was introduced into the reactor and the temperature was maintained at room temperature for 5 hours. After the reaction, samples were taken and qualitative and quantitative tests were performed using GC-MS (Shimadzu) and GC (Agilent). The test results are listed in Table 1 as serial numbers 21-22.

[0029] Table 1 Test results in each embodiment Table 2 Test results of Example 19 Table 3 Test results of Example 20 The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural, characterized in that: The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural is as follows: 5-hydroxymethylfurfural is used as a raw material, a nitrogen-doped carbon-loaded cobalt-based bimetal is used as a catalyst, a xenon lamp is used as a light source system in a low-grade alcohol solution, and oxygen in the air or pure oxygen is used as an oxygen source to carry out an oxidation reaction under normal pressure to obtain the target dimethyl 2,5-furandicarboxylate; the other metal in the nitrogen-doped carbon-loaded cobalt-based bimetal is iron, ruthenium, tantalum, platinum, silver, palladium, manganese, potassium, cerium, nickel or copper.

2. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to claim 1, characterized in that: The molar ratio of cobalt to another metal in the nitrogen-doped carbon-supported cobalt-based bimetal is 1:(0.01-0.5).

3. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to claim 1, characterized in that: The metal loading amount in the nitrogen-doped carbon-loaded cobalt-based bimetallic is 1-10wt%.

4. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to any one of claims 1 to 3, characterized in that: The mass ratio of the amount of the nitrogen-doped carbon-loaded cobalt-based bimetal to the raw material 5-hydroxymethylfurfural is (0.1~1):

1.

5. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to claim 1, characterized in that: The temperature of the oxidation reaction is room temperature.

6. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to claim 1, characterized in that: The oxidation reaction time is 1 to 30 hours.

7. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to claim 1, characterized in that: The concentration of the raw material 5-hydroxymethylfurfural in the low-grade alcohol solvent is 8-800 mM.

8. The method for preparing dimethyl 2,5-furandicarboxylate by photocatalytic oxidation of 5-hydroxymethylfurfural according to claim 1 or 7, characterized in that: The lower alcohol is methanol, ethanol, propanol or butanol.

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