Ternary metal oxide catalyst for synthesizing 2, 5-furandicarboxylic acid and preparation method thereof

Abstract

The invention discloses a ternary metal oxide catalyst for synthesizing 2, 5-furandicarboxylic acid and a preparation method of the ternary metal oxide catalyst, and the ternary metal oxide catalyst comprises an active metal A, a co-metal B and a carrier metal C. The preparation of a precursor is completed in ethanol by taking oxalic acid or citric acid and the like as a chelating agent, and then the ternary metal oxide catalyst can be obtained through high-temperature calcination. When the catalyst is applied to a reaction (FDCA) for synthesizing 2, 5-furandicarboxylic acid by using 5-hydroxymethylfurfural, an excellent effect is achieved no matter oxygen or air is used as an oxygen source, the highest yield of the FDCA reaches 92.5%, and the reaction stability is high. The non-noble metal catalyst provided by the invention is used for synthesizing 2, 5-furandicarboxylic acid, and the cost of the catalyst is remarkably reduced on the premise of keeping relatively high product yield.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, in particular to a ternary metal oxide catalyst for synthesizing 2,5-furandicarboxylic acid and a preparation method thereof. Background Art

[0002] Today's society relies on the deep development of fossil fuels to provide many fuels and chemicals needed by humans in daily life, and the dependence on fossil fuel resources is becoming increasingly strong. However, due to the non-renewable nature of fossil fuels and the high intensity of global mining, its cost will gradually increase and the supply will gradually decrease. In addition, fossil fuels will produce a large amount of carbon emissions during the collection and development process, causing greenhouse effects and a large number of natural disasters. Therefore, people have a strong interest in sustainable green energy and chemical raw materials, especially biomass resources.

[0003] Biomass resources are rich in carbohydrates, which can be degraded to obtain monosaccharides such as glucose and fructose after pretreatment. These sugars can be dehydrated to obtain an important biomass platform compound, 5-hydroxymethylfurfural (HMF), which is an important raw material for the final synthesis of 2,5-furandicarboxylic acid (FDCA). The molecular structure of FDCA contains a furan ring structure. When used as a monomer for synthesizing polymer materials, it can provide excellent heat resistance and mechanical strength. It is considered to be an ideal substitute for petroleum-based monomer terephthalic acid (PTA) and an excellent green packaging material in the future. Therefore, the development of a synthetic method for 2,5-furandicarboxylic acid has important application value and significance for the sustainable development of biomass.

[0004] In the research and development process of preparing FDCA from HMF, catalysts are an indispensable part. Homogeneous catalysts mainly include transition metal salts such as Co and Mn and halogens such as bromine. The homogeneous catalytic system has the disadvantages of low FDCA yield, difficult separation of metal salts, and great harm of halogens to the reactor and the environment. In contrast, the FDCA selectivity of the heterogeneous catalytic system is higher and easy to separate. After using noble metal heterogeneous catalysts such as Pt, Pd and Au, FDCA can achieve excellent yields (>90%). However, such noble metal catalysts are expensive, which increases the cost of large-scale production of FDCA and is not conducive to its commercial development. Existing non-noble metal heterogeneous catalysts generally have poor stability and low selectivity when oxidized with oxygen or air. Therefore, it is urgent to develop an efficient and stable non-noble metal heterogeneous catalyst for HMF oxidation to produce FDCA. Summary of the invention

[0005] The purpose of the present invention is to provide a ternary metal oxide catalyst and a preparation method thereof, which are applied to the reaction of HMF oxidation to produce FDCA, so as to improve the product yield and stability of the catalyst in the reaction.

[0006] The purpose of the present invention can be achieved by the following technical solutions: The catalyst for synthesizing 2,5-furandicarboxylic acid in the present invention contains three metal components A, B and C, wherein metals A and B are active metal components, and metal C is a carrier component.

[0007] Further preferably, metal A is Co, with a content of 5-10wt%; metal B is Cu, Fe and Mn, with a content of 2-5wt%; and metal C is Ce, with a content of 70-80wt%.

[0008] The preparation method of the ternary metal oxide catalyst for synthesizing 2,5-furandicarboxylic acid in the present invention comprises the following steps: S1: Add the ethanol solution containing the chelating agent M dropwise to the vigorously stirred ethanol solution containing the metal C salt, and keep stirring vigorously for 0.5-1h. Separate the solid in the solution by centrifugation and disperse it again in ethanol to obtain solution a; S2: Add the ethanol solution containing metal A and B salts and the ethanol solution containing chelating agent M to solution a at the same time, and keep stirring for 3-5 hours to obtain solution b; S3: Separate the solid from solution b by centrifugation and wash it with ethanol several times. Place the solid in an oven at 60 °C for 12 h to obtain powder c; S4: Place powder c in a muffle furnace, heat to 300-500 °C and calcine for 3-5 hours to obtain the final catalyst.

[0009] Furthermore, the metal C salt described in S1 and S2 is a nitrate.

[0010] Furthermore, the chelating agent M described in S1 and S2 is oxalic acid.

[0011] Furthermore, the concentration of the chelating agent M in the ethanol solution containing the chelating agent M described in S1 and S2 is 0.5-1 mol / L.

[0012] Furthermore, the ternary metal oxide catalyst is used for the reaction of oxidizing 5-hydroxymethylfurfural with air or oxygen to synthesize 2,5-furandicarboxylic acid.

[0013] Compared with the prior art, the present invention has the following technical advantages: The present invention provides a simple preparation method of a ternary metal oxide catalyst, which improves the dispersion of active metal on the surface of a carrier metal by introducing a chelating agent, and is applied to the reaction of preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural. The catalyst has a stable structure and high product selectivity under a strong oxidizing environment, and the preparation method is simple and suitable for industrial large-scale production.

[0014] The technical solution of the present invention is described below with examples, but the protection scope of the present invention is not limited thereto. DETAILED DESCRIPTION

[0016] Example 1 In this embodiment, CoCu / CeO 2 Preparation of catalyst, Co content is 5wt%, Cu content is 1wt% S1: Add 0.5M oxalic acid ethanol solution dropwise to a vigorously stirred 50mL ethanol solution containing 10mmol cerium nitrate, and keep stirring vigorously for 1h. Separate the solid in the solution by centrifugation and redisperse it in 50mL ethanol to obtain solution a; S2: Add 20 mL of ethanol solution containing 1.6 mmol of cobalt nitrate and 0.3 mmol of copper nitrate and 0.5 M ethanol solution of oxalic acid to solution a at the same time, and keep stirring for 3-5 hours to obtain solution b; S3: Separate the solid from solution b by centrifugation and wash it with ethanol several times. Place the solid in an oven at 60 °C for 12 h to obtain powder c; S4: Powder c was placed in a muffle furnace, heated to 400 °C and calcined for 3 h to obtain the final catalyst.

[0017] Example 2 In this embodiment, CoFe / CeO 2 Preparation of catalyst, Co content is 5wt%, Fe content is 1wt% S1: Add 0.5M oxalic acid ethanol solution dropwise to a vigorously stirred 50mL ethanol solution containing 10mmol cerium nitrate, and keep stirring vigorously for 1h. Separate the solid in the solution by centrifugation and redisperse it in 50mL ethanol to obtain solution a; S2: Add 20 mL of ethanol solution containing 1.6 mmol of cobalt nitrate and 0.33 mmol of ferric nitrate and 0.5 M ethanol solution of oxalic acid to solution a at the same time, and keep stirring for 3-5 hours to obtain solution b; S3: Separate the solid from solution b by centrifugation and wash it with ethanol several times. Place the solid in an oven at 60 °C for 12 h to obtain powder c; S4: Powder c was placed in a muffle furnace, heated to 400 °C and calcined for 3 h to obtain the final catalyst.

[0018] Example 3 In this embodiment, CoMn / CeO 2 Preparation of catalyst, Co content is 5wt%, Mn content is 1wt% S1: Add 0.5M oxalic acid ethanol solution dropwise to a vigorously stirred 50mL ethanol solution containing 10mmol cerium nitrate, and keep stirring vigorously for 1h. Separate the solid in the solution by centrifugation and redisperse it in 50mL ethanol to obtain solution a; S2: Add 20 mL of ethanol solution containing 1.6 mmol of cobalt nitrate and 0.34 mmol of manganese nitrate and 0.5 M ethanol solution of oxalic acid to solution a at the same time, and keep stirring for 3-5 hours to obtain solution b; S3: Separate the solid from solution b by centrifugation and wash it with ethanol several times. Place the solid in an oven at 60 °C for 12 h to obtain powder c; S4: Powder c was placed in a muffle furnace, heated to 400 °C and calcined for 3 h to obtain the final catalyst.

[0019] Embodiment 4-6

[0020] The above embodiment is still the preparation of the catalyst, and the preparation method is the same as that of Examples 1 to 3, except that the content of the B-site metal becomes 3 wt %.

[0021] Example 7 This example examines the results of the above catalyst using oxygen in the synthesis of 2,5-furandicarboxylic acid 0.015 g of 5-hydroxymethylfurfural, 0.02 g of sodium bicarbonate and 3 mL of water were added to a 20 mL batch reactor, and 10 mg of catalyst was added. The gas in the batch reactor was replaced with nitrogen, and then 9 bar of oxygen was filled as an oxygen source. When the temperature of the batch reactor rose to 100 °C, magnetic stirring was started and the reaction was maintained for 10 h. After the reaction was completed, the liquid was collected and the catalyst was separated by centrifugation. The conversion rate of 5-hydroxymethylfurfural and the yield of 2,5-furandicarboxylic acid were analyzed by high performance liquid chromatography.

[0022] Example 8 This example investigates the results of the above catalyst using air in the synthesis of 2,5-furandicarboxylic acid. The specific operation is the same as that of Example 7, except that 9 bar of air is charged into the batch reactor as an oxygen source.

[0023] This example investigates the results of the above catalyst using air in the synthesis of 2,5-furandicarboxylic acid. The specific operation is the same as that of Example 7, except that 9 bar of air is charged into the batch reactor as an oxygen source.

[0024] Table 1 Performance data of each catalyst in Example 7 catalyst HMF conversion rate (%) FDCA yield (%) <![CDATA[5CoCu / CeO 2 ]]> >99 92.5 <![CDATA[5CoFe / CeO 2 ]]> >99 85.9 <![CDATA[5CoMn / CeO 2 ]]> >99 89.2 <![CDATA[5Co3Cu / CeO 2 ]]> >99 90.3 <![CDATA[5Co3Fe / CeO 2 ]]> >99 81.2 <![CDATA[5Co3Mn / CeO 2 ]]> >99 85.5

[0025] From the data in Table 1, it can be seen that Co is the main active metal, CeO2 The ternary metal oxide catalysts with Cu, Fe and Mn as the support and 5CoCu / CeO as the co-metal all showed excellent FDCA yield in the synthesis of 2,5-furandicarboxylic acid. 2 The catalyst can achieve a maximum FDCA yield of 92.5%. At the same time, it can be observed that excessive metal promoters may cover some active sites, leading to a decrease in FDCA yield.

[0026] Table 2 Performance data of each catalyst in Example 8 catalyst HMF conversion rate (%) FDCA yield (%) <![CDATA[5CoCu / CeO 2 ]]> >99 89.6 <![CDATA[5CoFe / CeO 2 ]]> >99 79.8 <![CDATA[5CoMn / CeO 2 ]]> >99 81.4 <![CDATA[5Co3Cu / CeO 2 ]]> 98.2 86.1 <![CDATA[5Co3Fe / CeO 2 ]]> 96.4 75.3 <![CDATA[5Co3Mn / CeO 2 ]]> 96.9 76.7

[0027] It can be seen from the data in Table 2 that after using air as the oxygen source, the yield of FDCA also decreases due to the decrease in oxygen partial pressure, but it is not obvious, indicating that the catalyst can also complete the oxidation reaction well at a lower oxygen partial pressure.

[0028] Example 9 This example investigates the stability of the catalysts in Examples 1 to 3 in the reaction of synthesizing 2,5-furandicarboxylic acid with oxygen. After each reaction, the centrifuged catalyst was collected and washed with deionized water, and then put into the next reaction. After 8 cycles, the yield of FDCA still remained 90% of the initial reaction. This shows that the reaction stability of the ternary metal oxide catalyst is very excellent.

[0029] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A ternary metal oxide catalyst for synthesizing 2,5-furandicarboxylic acid and a preparation method thereof, characterized in that: The catalyst comprises three metal components A, B and C, wherein metals A and B include but are not limited to Co, Mn, Fe, Cu, Zn and Ni, and metal C includes but is not limited to Al, Ce, Zr and La.

2. A ternary metal oxide catalyst for synthesizing 2,5-furandicarboxylic acid according to claim 1, characterized in that: Metals A and B are used as active metals, and their contents are 2-10 wt% respectively; metal C is used as a carrier, and its content is 50-80 wt%.

3. The method for preparing a ternary metal oxide catalyst according to claim 1, characterized in that: The following steps are involved: S1: Add the ethanol solution containing the chelating agent M dropwise to the vigorously stirred ethanol solution containing the metal C salt, and keep stirring vigorously for 0.5-1h. Separate the solid in the solution by centrifugation and redisperse it in ethanol to obtain solution a; S2: Add the ethanol solution containing metal A and B salts and the ethanol solution containing chelating agent M to solution a at the same time, and keep stirring for 3-5 hours to obtain solution b; S3: Separate the solid from solution b by centrifugation and wash it with ethanol several times. Place the solid in an oven at 60 °C for 12 h to obtain powder c; S4: Place powder c in a muffle furnace, heat to 300-500 °C and calcine for 3-5 hours to obtain the final catalyst.

4. The method for preparing a ternary metal oxide catalyst according to claim 4, characterized in that: The metal C salt described in S1 and S2 is one or more of nitrate, sulfate or chloride.

5. The method for preparing a ternary metal oxide catalyst according to claim 4, characterized in that: The chelating agent M described in S1 and S2 is one or more of oxalic acid, citric acid, tartaric acid or ethylenediamine.

6. The method for preparing a ternary metal oxide catalyst according to claim 4, characterized in that: The concentration of the chelating agent M in the ethanol solution containing the chelating agent M described in S1 and S2 is 0.1~1 mol / L.

7. The method for preparing a ternary metal oxide catalyst according to claim 4, characterized in that: Used in the reaction of oxidizing 5-hydroxymethylfurfural with air or oxygen to synthesize 2,5-furandicarboxylic acid.