Noble metal catalysts, methods for their preparation and use, and methods for preparing 2,5-furandicarboxylic acid

Abstract

The application relates to the chemical technology field and discloses a noble metal catalyst, a preparation method and application of the noble metal catalyst and a preparation method of 2,5-furan dicarboxylic acid. The catalyst comprises sulfur-doped nanometer carbon cages and active components loaded on the sulfur-doped nanometer carbon cages, the active components are selected from at least one of Ru and optionally Pt, Pd and Au; the sulfur-doped nanometer carbon cages have micropore structures and mesopore structures, the BET specific surface area of the sulfur-doped nanometer carbon cages is greater than 500 m 2 / g, the proportion of the specific surface area in micropores in the total specific surface area is lower than 30%; the total pore volume of the sulfur-doped nanometer carbon cages is greater than 1 cm 3 / g, the proportion of the micropore volume in the total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanometer carbon cages is 80-98% and the mass percentage of sulfur is 0.1-10% as measured by X-ray photoelectron spectroscopy. The catalyst can be used for preparing 2,5-furan dicarboxylic acid without the need of alkaline compounds and acidification treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical technology, in particular to a noble metal catalyst, a preparation method and application thereof, and a preparation method of 2,5-furan dicarboxylic acid. BACKGROUND

[0002] 2,5-furan dicarboxylic acid (FDCA) is also known as dehydrogallic acid and furan carboxylic acid, which is a high-value biological and chemical substance. In recent years, it has been used to synthesize polymers with high value as a substitute for petroleum chemical derivatives terephthalic acid, and has great market development potential. FDCA can be applied in many fields. FDCA monomer can be used to prepare various polymers such as polyesters, polyamides, polyurethanes, etc.; FDCA lipid compounds are considered to be a substitute for terephthalate plasticizers for PVC production; FDCA, mainly composed of polycarboxylic acid, is one of the important components of foam extinguishing agents, which helps to achieve the purpose of extinguishing in a very short time; it can be used as a precursor of levulinic acid and succinic acid; in the medical field, diethyl ester in FDCA has a strong anesthetic effect similar to cocaine, and research has also found that it has strong antibacterial properties. The most common synthesis method of FDCA at present is to oxidize 5-hydroxymethylfurfural (5-HMF) to prepare FDCA, in which 5-HMF is usually converted from hexose dehydration.

[0003] In the process of preparing FDCA by selective oxidation of HMF, because the solubility of FDCA in water is low (<1 g / 100 mL water, 100℃), researchers often add basic compounds to the reaction process to generate soluble salt compounds of FDCA product, so as to improve the single-pass processing capacity of the process method. However, the salt compounds of FDCA obtained by these methods cannot be directly used in the production of polymers and other processes, and must be treated by acidification (pH about 1) to convert them back to FDCA products, which undoubtedly increases the complexity of the overall FDCA production process and reduces its environmental friendliness. CN108779088A discloses a method for preparing FDCA from HMF in one or two steps without introducing basic compounds. This method effectively improves the solubility of FDCA by using a mixed solvent of water and an organic solvent. The catalyst used in this method is a supported metal catalyst, in which the metal component is Pt or Au. Because the prices of Pt and Au are relatively high (about 300-400 yuan / gram), the overall process method is correspondingly high in cost, which makes it difficult to be practically applied. Therefore, it is urgent to develop a low-cost high-efficiency catalyst to realize the conversion of HMF to FDCA under alkali-free conditions.

[0004] It is to be noted that the information disclosed in the foregoing Background section is only for the purpose of enhancing the understanding of the background of the present application and therefore it can include information which can not constitute the prior art to those skilled in the art. SUMMARY

[0005] The present application aims to overcome the problem of complex preparation process of 2,5-furan dicarboxylic acid in the prior art, and provides a noble metal catalyst, a preparation method and application thereof, and a preparation method of 2,5-furan dicarboxylic acid, which uses a high specific surface area sulfur-doped nanocarbon cage as a carrier to improve the activity of the catalyst, and realizes the reaction process of preparing 2,5-furan dicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF) under an alkali-free condition.

[0006] To achieve the above-mentioned purpose, the present application provides a noble metal catalyst in the first aspect, wherein the catalyst comprises a sulfur-doped nanocarbon cage and an active component loaded on the sulfur-doped nanocarbon cage, the active component is selected from at least one of Ru and optionally Pt, Pd and Au; wherein the sulfur-doped nanocarbon cage has a microporous structure and a mesoporous structure, the BET specific surface area of the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, the proportion of the specific surface area in the micropore to the total specific surface area is less than 30%; the total pore volume of the sulfur-doped nanocarbon cage is greater than 1 cm 3 / g, the proportion of the pore volume in the micropore to the total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage is 80-98% and the mass percentage of sulfur is 0.1-10% as measured by X-ray photoelectron spectroscopy.

[0007] The present application provides a preparation method of a noble metal catalyst in the second aspect, wherein the method comprises:

[0008] S1, drying after introducing an active component into a sulfur-doped nanocarbon cage to obtain a catalyst precursor;

[0009] S2, calcining the catalyst precursor obtained in step S1 under a calcination atmosphere, and treating under a reducing atmosphere to obtain a noble metal catalyst;

[0010] wherein the active component is at least one of Ru and optionally Pt, Pd and Au;

[0011] wherein the sulfur-doped nanocarbon cage has a microporous structure and a mesoporous structure, the BET specific surface area of the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, the proportion of the specific surface area in the micropore to the total specific surface area is less than 30%; the total pore volume of the sulfur-doped nanocarbon cage is greater than 1 cm 3The ratio of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the sulfur-doped nanocarbon cage is 80-98% and the mass percentage of sulfur is 0.1-10% as measured by X-ray photoelectron spectroscopy.

[0012] The third aspect of the present application provides a noble metal catalyst prepared by the preparation method of the second aspect.

[0013] The fourth aspect of the present application provides an application of the noble metal catalyst of the first aspect or the third aspect in the preparation of 2,5-furan dicarboxylic acid.

[0014] The fifth aspect of the present application provides a preparation method of 2,5-furan dicarboxylic acid, wherein the method comprises: reacting 5-hydroxymethylfurfural with an oxygen-containing gas in the presence of the noble metal catalyst of the first aspect or the third aspect and a mixed solvent to obtain 2,5-furan dicarboxylic acid; wherein the mixed solvent is a mixed solvent containing an organic solvent and / or water.

[0015] The inventors of the present application found in research that using high specific surface area sulfur-doped nanocarbon cages as a carrier of a noble metal catalyst, on the one hand, the multi-level porous carbon material has a rich pore structure, which increases its specific surface area and improves intrinsic activity; on the other hand, the three-dimensional interconnected channels thereof can provide multi-directional and high-flux mass transfer channels, thereby accelerating the surface / interface catalytic reaction kinetics. Using high specific surface area sulfur-doped nanocarbon cages as a carrier and cooperating with specific active components to prepare a catalyst, the reaction process of preparing 2,5-furan dicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF) is realized under an alkali-free condition.

[0016] The preparation method of 2,5-furan dicarboxylic acid in the present application uses a mixed solution of a specific proportion of an organic solvent and / or water as a reaction solvent, which increases the solubility of the product 2,5-furan dicarboxylic acid, avoids the introduction of an alkaline compound, and at the same time simplifies the post-processing steps of the product, avoiding the generation of a large amount of waste acid and waste water in the subsequent acidification process; at the same time, the Ru-based catalyst supported by the sulfur-doped nanocarbon cage used in the present application as a catalyst has high oxidation activity and high yield of furan dicarboxylic acid (FDCA), and the reaction process is green and simple, which is a very potential method for preparing furan dicarboxylic acid (FDCA) in industry. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a high-resolution transmission electron microscope image of the sulfur-doped nanocarbon cage prepared in Preparation Example 1;

[0018] Figure 2 is an X-ray photoelectron spectroscopy (XPS) image of the sulfur-doped nanocarbon cage prepared in Preparation Example 1;

[0019] Figure 3is the S2p spectrum of XPS of the sulfur-doped nanocarbon cage prepared in Preparation Example 1;

[0020] Figure 4 is the nitrogen isothermal adsorption / desorption curve of the sulfur-doped nanocarbon cage prepared in Preparation Example 1;

[0021] Figure 5 is the mesopore size pore volume distribution curve of the sulfur-doped nanocarbon cage prepared in Preparation Example 1;

[0022] Figure 6 is the micropore size pore volume distribution curve of the sulfur-doped nanocarbon cage prepared in Preparation Example 1;

[0023] Figure 7 is the high-resolution transmission electron micrograph of the sulfur-doped nanocarbon cage prepared in Preparation Example 3. DETAILED DESCRIPTION

[0024] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are provided as approximate descriptions of the ranges and are understood to be open-ended. Each range disclosed herein is to be understood to include individual numbers falling within the range, intervening ranges, and individual points falling within the range, unless the context clearly indicates otherwise. Numeric ranges are inclusive of the numbers at the endpoints.

[0025] The first aspect of the present application provides a noble metal catalyst, wherein it comprises a sulfur-doped nanocarbon cage and an active component supported on the sulfur-doped nanocarbon cage, the active component being selected from at least one of Ru and optionally Pt, Pd and Au; wherein the sulfur-doped nanocarbon cage has a microporous structure and a mesoporous structure, the BET specific surface area of the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, the proportion of micropore specific surface area in the total specific surface area is less than 30%; the total pore volume of the sulfur-doped nanocarbon cage is greater than 1 cm 3 / g, the proportion of micropore pore volume in the total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanocarbon cage is 80-98% and the mass percentage of sulfur is 0.1-10% as measured by X-ray photoelectron spectroscopy.

[0026] The noble metal catalyst provided by the present application has a sulfur-doped nanocarbon cage with specific structure and properties as a carrier to support a specific active component, and has excellent activity for the preparation of 2,5-furan dicarboxylic acid, improves the yield of 2,5-furan dicarboxylic acid, and has excellent industrial prospects.

[0027] In the present application, "optionally at least one of Pt, Pd and Au" means that the active component can contain at least one of Pt, Pd and Au, or can not contain at least one of Pt, Pd and Au. In a preferred embodiment, the active component is Ru. The advantage of using this preferred embodiment is that Ru has a lower price than several other metals, and has the best selectivity for the target product in the reaction.

[0028] In the present application, the content of each substance in the catalyst is not specifically limited. Preferably, the content of the sulfur-doped nanocarbon cage is 70-99% by mass, and the content of the active component is 1-30% by mass, based on the total amount of the catalyst; further preferably, the content of the sulfur-doped nanocarbon cage is 85-95% by mass, and the content of the active component is 5-15% by mass, based on the total amount of the catalyst. The advantage of using this preferred embodiment is that the catalyst has the best activity and selectivity for the target product within the above-mentioned preferred composition range.

[0029] According to some embodiments of the present application, the sulfur-doped nanocarbon cage has a microporous structure and a mesoporous structure, the BET specific surface area of the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, and the proportion of the specific surface area in the micropores to the total specific surface area is less than 30%. Preferably, the BET specific surface area of the sulfur-doped nanocarbon cage is 500-1600 m 2 / g, and the proportion of the specific surface area in the micropores to the total specific surface area is less than 20%.

[0030] According to some embodiments of the present application, the total pore volume of the sulfur-doped nanocarbon cage is greater than 1 cm 3 / g, and the proportion of the micropore volume to the total pore volume is less than 15%. Preferably, the total pore volume of the sulfur-doped nanocarbon cage is greater than 1.4 cm 3 / g, and the proportion of the micropore volume to the total pore volume is less than 10%. More preferably, the total pore volume of the nanocarbon cage is 1.4-3.6 cm 3 / g, and the proportion of the micropore volume to the total pore volume is 2.5-4.5%.

[0031] According to some embodiments of the present application, preferably, in the pore size distribution curve of the nanocarbon cage, there is a micropore distribution peak at 0.59-0.63 nm, and there are two mesopore distribution peaks at 2.73-4.1 nm and 3.877-15.6 nm.

[0032] In the present application, the pore structure properties of the sulfur-doped nanocarbon cage are detected by BET test method. Specifically, the BET specific surface area and pore volume of the sulfur-doped nanocarbon cage are determined by using a Quantachrome AS-6B analyzer, and the mesopore distribution curve is calculated according to the Barrett-Joyner-Halenda (BJH) method on the desorption curve, and the micropore pore size distribution curve is calculated according to the Horvath-Kawazoe (HK) method on the isotherm curve.

[0033] According to some embodiments of the present application, the mass percentage of carbon on the surface of the sulfur-doped nanocarbon cage is 80-98% and the mass percentage of sulfur is 0.1-10% as measured by X-ray photoelectron spectroscopy. Preferably, the mass percentage of carbon on the surface of the nanocarbon cage is 84-95% and the mass percentage of sulfur is 0.2-5% as measured by X-ray photoelectron spectroscopy.

[0034] According to some embodiments of the present application, the sulfur-doped nanocarbon cage can also contain oxygen element, which can be formed on the surface of the sulfur-doped nanocarbon cage in various forms during the preparation of the sulfur-doped nanocarbon cage. Preferably, the mass percentage of oxygen on the surface of the nanocarbon cage is 2-15%, more preferably 4-15% as measured by X-ray photoelectron spectroscopy.

[0035] According to some embodiments of the present application, the sulfur-doped nanocarbon cage can contain doping elements applicable to nanocarbon materials known to those skilled in the art, and preferably, the sulfur-doped nanocarbon cage does not contain elements such as nickel, nitrogen, boron, phosphorus, fluorine, chlorine, bromine, iodine, etc.

[0036] According to some embodiments of the present application, the content of carbon element, sulfur element and oxygen element on the surface of the sulfur-doped nanocarbon cage is measured by X-ray photoelectron spectroscopy. The X-ray photoelectron spectroscopy analysis is tested on an ESCALab250 X-ray photoelectron spectrometer of Thermo Scientific company equipped with Thermo Avantage V5.926 software, the excitation source is monochromatic AlKα X-ray with energy of 1486.6 eV and power of 150 W, the penetration energy for narrow scanning is 30 eV, the base vacuum during analysis test is 6.53×10 -9 mbar, the electron binding energy is corrected with the C1s peak of elemental carbon (284.6 eV), the data processing is performed on Thermo Avantage software, and the quantitative analysis is performed in the analysis module by using the sensitivity factor method. Before testing, the sulfur-doped nanocarbon cage is dried in a helium atmosphere at a temperature of 150°C and 1 standard atmosphere for 3 hours.

[0037] According to some embodiments of the present application, preferably, the nanocarbon cage has a spherical or spherical-like morphology. Preferably, the diameter of the nanocarbon cage is 2-200 nm, further preferably 3-50 nm. In the present application, the surface morphology of the material is characterized by high-resolution transmission electron microscopy (HRTEM), and the model of the high-resolution transmission electron microscope used is JEM-2100 (Japan Electron Corporation). The high-resolution transmission electron microscope test conditions are: the acceleration voltage is 200 kV. The diameter of the nanocarbon cage can be measured by high-resolution transmission electron microscope pictures.

[0038] According to some embodiments of the present application, preferably, in the Raman curve of the sulfur-doped nanocarbon cage, the ratio of I D / I G is in the range of 0.5-1.5, further preferably 0.5-1.1. The nanocarbon cage of the present application has a clear D peak and G peak, and has a certain degree of graphitization. In the present application, the Raman test of the nanocarbon cage uses visible laser Raman measurement method, and a 532 nm light source is used to perform Raman characterization on the functional groups of the sulfur-doped nanocarbon cage to obtain a characteristic spectrum.

[0039] According to some embodiments of the present application, preferably, in the X-ray photoelectron spectrum of the sulfur-doped nanocarbon cage, the nanocarbon cage has characteristic spectral peaks of sulfur at 161±1 eV, 162-166 eV and 168±2 eV, or has characteristic spectral peaks of sulfur at 162-166 eV and 168±2 eV.

[0040] According to some embodiments of the present application, preferably, based on the total amount of sulfur on the surface of the sulfur-doped nanocarbon cage, the mass percentage of sulfur determined by the characteristic spectral peak corresponding to 162-166 eV in the X-ray photoelectron spectrum of the sulfur-doped nanocarbon cage is 2-90%, preferably 70-88%. In the present application, the above-mentioned characteristic spectral peak of sulfur in the X-ray photoelectron spectrum of the sulfur-doped nanocarbon cage is located at 162-166 eV, indicating that the sulfur in the nanocarbon cage of the present application is combined with carbon to form a C-S bond, and exists in the form of thiophenyl sulfur.

[0041] In the present application, the term "sulfur" in the term "sulfur-doped nanocarbon cage" refers to the element sulfur. Specifically, the term refers to the element sulfur in various forms formed on the surface of the sulfur-doped nanocarbon cage during the preparation of the sulfur-doped nanocarbon cage.

[0042] In the present application, the term "mesopore" is defined as a pore with a pore size in the range of 2-50 nm. Pores with a pore size less than 2 nm are defined as "micropores".

[0043] The second aspect of the present application provides a preparation method of a noble metal catalyst, wherein the method comprises:

[0044] S1, drying after introducing active components into the sulfur-doped nanocarbon cage to obtain a catalyst precursor;

[0045] S2, calcining the catalyst precursor obtained in step S1 under a calcination atmosphere, and treating under a reducing atmosphere to obtain a noble metal catalyst;

[0046] The active components are Ru and optionally at least one of Pt, Pd and Au.

[0047] The sulfur-doped nanocarbon cage has microporous structure and mesoporous structure, the BET specific surface area of the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, the proportion of micropore specific surface area in total specific surface area is less than 30%; the total pore volume of the sulfur-doped nanocarbon cage is greater than 1 cm 3 / g, the proportion of micropore pore volume in total pore volume is less than 15%; the mass percentage of carbon on the surface of the sulfur-doped nanocarbon cage is 80-98% and the mass percentage of sulfur is 0.1-10% measured by X-ray photoelectron spectroscopy.

[0048] According to some preferred embodiments of the present application, the preparation method of the sulfur-doped nanocarbon cage comprises the following steps:

[0049] A, precursor preparation: providing a homogeneous solution containing a nickel source, a multi-component organic carboxylic acid, a sulfur source and a solvent, and then removing the solvent in the homogeneous solution to obtain a complex precursor, wherein the sulfur source is selected from a Group IA hydrosulfate and / or sulfate;

[0050] B, calcination: under the protection of an inert atmosphere, the complex precursor obtained in step A is subjected to constant temperature calcination at a temperature of 450-700°C to obtain a pyrolysis product;

[0051] C, acid washing: providing an aqueous solution containing the pyrolysis product obtained in step B, and contacting with an acid to react, then solid-liquid separation, washing and drying.

[0052] According to some embodiments of the present application, a sulfate / hydrosulfate is used as a sulfur source and an activator in the preparation process of the sulfur-doped nanocarbon cage, and a nickel source and a multi-component organic carboxylic acid are used to prepare a complex precursor material, and by controlling the calcination temperature, a sulfur-doped nanocarbon cage with microporous structure and mesoporous structure is prepared, the BET specific surface area of the sulfur-doped nanocarbon cage is greater than 500 m 2 / g, the proportion of micropore specific surface area in total specific surface area is less than 30%; the total pore volume is greater than 1 cm 3The ratio of micropore volume to total pore volume is less than 15%; the mass percentage of carbon on the surface of the nanometer carbon cage is 80-98% and the mass percentage of sulfur is 0.1-10% measured by X-ray photoelectron spectroscopy. The method can simply and efficiently realize preparation of the sulfur-doped nanometer carbon cage, and the prepared sulfur-doped nanometer carbon cage has complete structure, high specific surface area and a large amount of mesoporous structure.

[0053] According to some embodiments of the present application, in step A, the formation of the homogeneous solution is not particularly limited, for example, the homogeneous solution can be formed by heating, and further preferably by heating and stirring. The present application also does not particularly limit the temperature of heating and the rate of stirring, which can form the homogeneous solution.

[0054] According to some embodiments of the present application, preferably, in step A, the nickel source is selected from at least one of organic acid salt, carbonate and basic carbonate containing nickel element, preferably carbonate and / or basic carbonate containing nickel element, and more preferably nickel basic carbonate.

[0055] According to some embodiments of the present application, preferably, the sulfur source is selected from at least one of potassium sulfate, sodium sulfate, potassium bisulfate and sodium bisulfate, more preferably potassium bisulfate and / or sodium bisulfate, and further preferably potassium bisulfate.

[0056] According to some embodiments of the present application, preferably, the polybasic organic carboxylic acid is selected from at least one of citric acid, maleic acid, trimesic acid, terephthalic acid and malic acid, more preferably citric acid and / or terephthalic acid.

[0057] According to some embodiments of the present application, preferably, in step A, the complex precursor material is obtained by dissolving the nickel source, the polybasic organic carboxylic acid and the sulfur source in a solvent to form a homogeneous solution, and then removing the solvent in the homogeneous solution. The type of the solvent is not particularly limited, which can form the homogeneous solution, preferably the solvent is water and / or ethanol, and more preferably water; the present application also does not particularly limit the amount of the solvent, which can also form the homogeneous solution. The solvent in the homogeneous solution can be removed by direct evaporation, and the temperature and process of evaporation can use the prior art known to those skilled in the art, for example, the solvent in the homogeneous solution can be removed by heating and evaporating.

[0058] In the present application, the amount of each substance in step A is not particularly limited. Preferably, in step A, the molar ratio of the nickel source, the polybasic organic carboxylic acid and the sulfur source, calculated as nickel element, is 1:0.1-10:0.1-2, preferably 1:0.5-3:0.3-2, and more preferably 1:0.7-1.5:0.5-1.2. The use of such preferred embodiments facilitates the preparation of the sulfur-doped nano-carbon cage with high specific surface area and containing both micropores and mesopores.

[0059] In the present application, the type of inert atmosphere in step B is not particularly limited, and the inert atmosphere commonly defined in the art is suitable for the present application. Preferably, in step B, the inert atmosphere is selected from at least one of nitrogen, argon, neon and helium, and is further preferably nitrogen.

[0060] According to some embodiments of the present application, in step B, the temperature of the constant temperature roasting is 450-700℃, and preferably the temperature of the constant temperature roasting is 500-650℃. In the present application, if the temperature of the constant temperature roasting is too low, the nickel element in the nano-carbon material cannot be completely removed, and if the temperature is too high, the structure of the nano-carbon cage will be affected and the yield of the carbon cage will be reduced. Only by controlling the temperature of the constant temperature roasting within the above limited range can the preparation of the sulfur-doped nano-carbon cage be realized.

[0061] In the present application, the roasting conditions in step B are not particularly limited. Preferably, the constant temperature roasting conditions include a temperature rising rate of 0.5-30℃ / min and a constant temperature time of 20-600min; and further preferably, the constant temperature roasting conditions include a temperature rising rate of 1-10℃ / min and a constant temperature time of 60-480min.

[0062] In the present application, the type of acid used in step C is not particularly limited, and the acid can be an acid commonly used in the art, as long as it can remove the nickel element in the pyrolysis product. Preferably, the acid is an aqueous inorganic acid and / or an aqueous organic acid, and is preferably one or more of an aqueous hydrochloric acid, an aqueous sulfuric acid, an aqueous nitric acid and an aqueous citric acid, and is further preferably an aqueous hydrochloric acid; preferably, the concentration of the aqueous inorganic acid and / or the aqueous organic acid is 0.1-10moL / L; and the pH value of the acid is less than 7. The present application does not have a particular requirement for the amount of acid, as long as it can remove the nickel element in the pyrolysis product.

[0063] In the present application, the contact reaction conditions in step C are not particularly limited. Preferably, in step C, the temperature for contacting the aqueous solution of the pyrolysis product with the acid is 20-120℃, and the time is 0.1-48h, and further preferably the temperature is 60-100℃ and the time is 4-12h.

[0064] According to some embodiments of the present application, the washing is used to remove the acid remaining on the sulfur-doped nanocarbon cage caused by the pickling process, and thus, various water washing methods capable of washing the sulfur-doped nanocarbon cage to neutral are suitable for the present application.

[0065] According to some embodiments of the present application, the drying is used to remove the water on the sulfur-doped nanocarbon cage. The drying can be performed by normal pressure drying or reduced pressure drying. Preferably, the drying is performed under the conditions of 100-120°C for 6-10h.

[0066] In the present application, the properties of the sulfur-doped nanocarbon cage, such as the diameter, BET specific surface area, total pore volume, pore distribution, and I D / I G The above has been described in the first aspect, and thus, will not be repeated here.

[0067] In the present application, the types and contents of the species in the sulfur-doped nanocarbon cage have been described in the first aspect, and thus, will not be repeated here.

[0068] In the present application, "optionally at least one of Pt, Pd and Au" means that the active component can contain at least one of Pt, Pd and Au, or can not contain at least one of Pt, Pd and Au. In a preferred embodiment, the active component in step S1 is Ru.

[0069] In the present application, the amount of each substance in the catalyst is not particularly limited. Preferably, the amounts of the sulfur-doped nanocarbon cage and the active component are such that, in the catalyst, the content of the sulfur-doped nanocarbon cage is 70-99 mass%, and the content of the active component is 1-30 mass% on an elemental basis, based on the total amount of the catalyst; further preferably, the amounts of the sulfur-doped nanocarbon cage and the active component are such that, in the catalyst, the content of the sulfur-doped nanocarbon cage is 85-95 mass%, and the content of the active component is 5-15 mass% on an elemental basis, based on the total amount of the catalyst.

[0070] In the present application, the active component is provided by its respective precursor. Preferably, the active component precursor is selected from a soluble salt solution of each active component, such as a chloride and / or nitrate.

[0071] In a preferred embodiment, the precursor of Ru is ruthenium chloride and / or ruthenium nitrate.

[0072] In a preferred embodiment, the precursor of Pt is chloroplatinic acid and / or platinum nitrate.

[0073] In a preferred embodiment, the precursor of Pd is palladium chloride and / or palladium nitrate.

[0074] In a preferred embodiment, the precursor of Au is chloroauric acid and / or gold nitrate.

[0075] In the present application, the drying condition in step S1 is not particularly limited, and can be selected from a wide range. For example, the drying condition can be normal pressure drying. Preferably, the drying condition comprises a temperature of 80-120℃ and a time of 8-20h.

[0076] In the present application, the calcination atmosphere in step S2 is not particularly limited, and can be selected from a wide range. Preferably, the calcination atmosphere is selected from at least one of nitrogen, argon, neon and helium, and is preferably nitrogen.

[0077] In the present application, the calcination condition in step S2 is not particularly limited, and can be selected from a wide range. Preferably, the calcination condition comprises a temperature of 300-800℃ and a time of 2-8h; further preferably, the calcination condition comprises a temperature of 400-600℃ and a time of 3-6h. The preferred embodiment has the advantage of removing Cl and other impurities in the metal component precursor sufficiently.

[0078] In a preferred embodiment, the noble metal catalyst is subjected to reduction treatment under a reducing atmosphere before use.

[0079] In the present application, the reducing atmosphere in step S2 is not particularly limited, and can be selected from a wide range. Preferably, the reducing atmosphere is hydrogen and optionally an inert gas selected from at least one of nitrogen, argon, neon and helium.

[0080] In a preferred embodiment, the reducing atmosphere is hydrogen and nitrogen.

[0081] In a preferred embodiment, the content of hydrogen in the reducing atmosphere is 5-30% by volume, and the content of nitrogen is 70-95% by volume.

[0082] In the present application, the reduction condition in step S2 is not particularly limited, and can be selected from a wide range. Preferably, the reduction condition comprises a temperature of 200-600℃, a time of 1-5h, and a volume space velocity of the reducing atmosphere of 1-100h -1 ; further preferably, the reduction condition comprises a temperature of 300-500℃, a time of 2-4h, and a volume space velocity of the reducing atmosphere of 5-50h -1 .

[0083] The preparation method of the noble metal catalyst is not particularly limited in the present application, and any conventional method can be used. For example, the noble metal catalyst can be prepared by impregnation, such as isochoric impregnation, incipient wetness impregnation, ion exchange, deposition-precipitation, vacuum impregnation, or the like. According to one embodiment of the present application, the noble metal catalyst can be prepared by incipient wetness impregnation, i.e., a solution containing a precursor of the active component is introduced into the sulfur-doped nanocarbon cage, and then impregnated at room temperature for 1-12 h, and then dried in an oven at 100-140 °C for 6-24 h. The obtained catalyst precursor is calcined in an inert gas (e.g., nitrogen) at a temperature of 300-800 °C for 2-8 h, and then reduced in a reducing atmosphere (e.g., a mixture of hydrogen and nitrogen) at a temperature of 200-600 °C for 1-5 h.

[0084] The third aspect of the present application provides a noble metal catalyst prepared by the preparation method of the second aspect.

[0085] According to one preferred embodiment of the present application, the types and contents of the components in the noble metal catalyst and the properties of the noble metal catalyst have been described in the second aspect, and will not be repeated here.

[0086] The fourth aspect of the present application provides a use of the noble metal catalyst of the first aspect or the third aspect in the preparation of 2,5-furan dicarboxylic acid.

[0087] The fifth aspect of the present application provides a method for preparing 2,5-furan dicarboxylic acid, wherein the method comprises: reacting 5-hydroxymethylfurfural with an oxygen-containing gas in the presence of the noble metal catalyst of the first aspect or the third aspect and a mixed solvent to obtain 2,5-furan dicarboxylic acid.

[0088] The mixed solvent is a mixed solvent containing an organic solvent and / or water.

[0089] In one preferred embodiment, the mixed solvent is a mixed solvent of an organic solvent and water.

[0090] The present application uses a mixed solution of water and / or an organic solvent in a specific ratio as a reaction solvent, which increases the solubility of the product 2,5-furan dicarboxylic acid, avoids the introduction of basic compounds, and simplifies the post-processing steps of the product, avoiding the generation of a large amount of waste acid and waste water in the subsequent acidification process. At the same time, the present application uses a sulfur-doped nanocarbon cage as a carrier to load the active component of the noble metal catalyst, which improves the yield of 2,5-furan dicarboxylic acid and makes the reaction process green and simple.

[0091] In the present application, the type of organic solvent is not particularly limited, and the organic solvent defined conventionally in the art is suitable for the present application. Preferably, the organic solvent is selected from at least one of tetrahydrofuran, 1,4-dioxane, gamma-valerolactone and dimethyl sulfoxide, and further preferably 1,4-dioxane. The use of the above-mentioned organic solvent has the advantage of significantly increasing the saturated solubility of FDCA after forming a mixed solution with water.

[0092] In a preferred embodiment, the mass ratio of the organic solvent to water in the mixed solvent is 10:1-0.1:1, preferably 4:1-0.4:1.

[0093] In a preferred embodiment, the content of 5-hydroxymethylfurfural is 0.1-20 mass%, preferably 0.5-20 mass%, and more preferably 1-10 mass% based on the total amount of the solution of 5-hydroxymethylfurfural and the mixed solvent. The use of this preferred embodiment has the advantage of controlling the concentration of the generated FDCA within the saturated solubility of FDCA corresponding to the reaction conditions, thereby avoiding the crystallization of FDCA during the reaction.

[0094] In a preferred embodiment, the molar ratio of the active component in the noble metal catalyst to 5-hydroxymethylfurfural is 1:1-1000, preferably 1:5-250, and more preferably 1:5-35. The use of this preferred embodiment has the advantage that the appropriate ratio range can accelerate the conversion of intermediate species during the reaction under the condition of less noble metal consumption, thereby avoiding the occurrence of side reactions.

[0095] In the present application, the type of oxygen-containing gas is selected from a wide range as long as it can provide oxygen. Preferably, the oxygen-containing gas is selected from one of pure oxygen, air and a mixed gas of oxygen and an inert gas selected from at least one of nitrogen, argon, neon and helium.

[0096] In a preferred embodiment, the partial pressure of the oxygen-containing gas is 0.5-5 MPa, preferably 1-3 MPa.

[0097] In the present application, the reaction conditions are not particularly limited as long as 2,5-furandicarboxylic acid can be prepared. Preferably, the reaction temperature is 50-170°C, and the time is 4-40 h, and further preferably, the temperature is 90-150°C, and the time is 6-20 h.

[0098] In the present application, the reaction is carried out under stirring, and the present application does not particularly limit the stirring conditions. Preferably, the stirring speed is 500-1000 rpm.

[0099] In a preferred embodiment, solid-liquid separation is performed on the reaction product after the reaction is completed. The method of solid-liquid separation is not particularly limited in the present application and can be performed using a method known in the art, for example, filtration.

[0100] In a preferred embodiment, the filter cake obtained after the reaction product is washed and subjected to solid-liquid separation is washed with a washing solvent. The type of washing solvent is not particularly limited in the present application. Preferably, the mixed solvent used in the reaction is selected as the washing solvent. The method of washing is also not particularly limited in the present application and can be performed using a method conventionally defined in the art.

[0101] In the present application, the reaction product is analyzed using high performance liquid chromatography. Preferably, the conditions of the high performance liquid chromatography include using an Alltech OA-1000 organic acid chromatographic column, a UV detector, a mobile phase of 0.005 mol / L H2SO4 aqueous solution, a flow rate of 0.6 mL / min, and a column temperature of 70°C.

[0102] The present application will be described in detail below through examples.

[0103] Unless otherwise specified, the reagents used in the present application are of analytical purity and are commercially available.

[0104] The surface morphology of the material is characterized by high resolution transmission electron microscopy (HRTEM). The model of the high resolution transmission electron microscope used is JEM-2100 (Japan Electron Corporation), and the test conditions of the high resolution transmission electron microscope are as follows: an acceleration voltage of 200 kV. The diameter of the sulfur-doped nanocarbon cage is measured from the electron microscope image.

[0105] The pore structure properties of the material are detected by the BET test method. Specifically, the specific surface area and pore volume of the material are obtained by the Brunauer-Emmett-Taller (BET) method, and the mesopore distribution curve is calculated from the desorption curve according to the Barrett-Joyner-Halenda (BJH) method using a Quantachrome AS-6B type analyzer.

[0106] The content of each element on the surface of the material is determined by X-ray photoelectron spectroscopy (XPS). The X-ray photoelectron spectroscopy analysis is performed on an ESCALab250 X-ray photoelectron spectrometer equipped with Thermo Avantage V5.926 software from Thermo Scientific Corporation, the excitation source is monochromatic Al Kα X-ray, the energy is 1486.6 eV, the power is 150 W, the penetration energy used for narrow scanning is 30 eV, and the base vacuum during analysis and testing is 6.53×10 -9mbar, electron binding energy was corrected using the C1s peak (284.6 eV) of elemental carbon, data processing was performed on ThermoAvantage software, and quantitative analysis was performed using the sensitivity factor method in the analysis module.

[0107] The degree of graphitization of the material was characterized by Raman spectroscopy at 1355 cm⁻¹. -1 The peak (D peak) is attributed to structural defects, consisting of amorphous carbon, at 1585 cm⁻¹. -1 The peak (G peak) is attributed to carbon in a planar structure. I0 is typically used. D / I G The degree of graphitization of a material is characterized by the intensity ratio of the D peak to the G peak. D / I G The higher the value, the more defects and the lower the degree of graphitization. The Raman spectrum of the material was obtained using an RM2000 microconfocal Raman spectrometer (Reinshaw product). Technical specifications: The excitation source was a He-Ne laser with a wavelength of 525 nm.

[0108] In this invention, high performance liquid chromatography (HPLC) is used to analyze the reaction products of 2,5-furandicarboxylic acid. The HPLC conditions include using an Alltech OA-1000 organic acid column, a UV detector, a mobile phase of 0.005 mol / L H2SO4 aqueous solution, a flow rate of 0.6 mL / min, and a column temperature of 70 °C.

[0109] Preparation Examples 1-3 are used to illustrate the preparation of sulfur-doped carbon nanocages.

[0110] Preparation Example 1

[0111] (1) Preparation of precursor: According to the molar ratio of nickel source (calculated as nickel element), poly-organic carboxylic acid and sulfur source of 1:0.7:1, 30g of basic nickel carbonate, 29.4g of citric acid and 27.8g of potassium hydrogen sulfate were weighed and added to a beaker containing 50mL of deionized water. The mixture was stirred at 70℃ to obtain a homogeneous solution, and then heated to dryness to obtain the complex precursor material.

[0112] (2) Calcination: The precursor material of the complex was placed in a ceramic boat, and then the ceramic boat was placed in the constant temperature zone of a tube furnace. Nitrogen gas with a flow rate of 100 mL / min was introduced, and the temperature was raised to 650℃ at a rate of 2.5℃ / min. After holding the temperature for 2 hours, the heating was stopped, and the temperature was cooled to room temperature under a nitrogen atmosphere to obtain the pyrolysis product.

[0113] (3) Acid washing: The pyrolysis product was added to a 2.0M HCl aqueous solution and stirred at 80℃ for 10h. Then it was filtered and washed with deionized water until the filtrate was neutral. The filter cake was then dried at 140℃ for 2h to obtain sulfur-doped nano carbon cage Z1.

[0114] The high-resolution transmission electron microscope image of the sulfur-doped carbon nanocage is shown below. Figure 1 As shown, from Figure 1 It can be seen that the sulfur-doped carbon nanocage has a spherical or near-spherical morphology, and the diameter of the carbon nanocage is 20-30 nm.

[0115] The X-ray photoelectron spectroscopy (XPS) spectrum of the sulfur-doped carbon nanocage is shown below. Figure 2 As shown, from Figure 2 The presence of distinct XPS peaks for C, O, and S confirms the effective doping of sulfur. Based on the peak areas, the mass percentage of each element on the surface of the sulfur-doped carbon nanocage can be calculated: carbon accounts for 91.81%, oxygen for 4.95%, and sulfur for 3.24%.

[0116] XPS S2p test of the sulfur-doped carbon nanocage is as follows: Figure 3 As shown in the figure, characteristic spectral peaks of sulfur exist at 162-166 eV and 168±2 eV. Based on the area of ​​the accumulated peaks after peak splitting, it can be calculated that the sulfur content corresponding to the characteristic spectral peak at 162-166 eV accounts for 86.44% of the total sulfur content.

[0117] The isothermal adsorption-desorption curves and pore volume-to-pore size distribution curves of the sulfur-doped carbon nanocage are shown below. Figure 4 , Figure 5 and Figure 6 As shown, the BET specific surface area of ​​the sulfur-doped carbon nanocage was calculated to be 1539.772 m² using isothermal adsorption-desorption curves. 2 / g, the specific surface area within the micropores is 221.386m². 2 / g, accounting for 14.4% of the total specific surface area; the total pore volume of the sulfur-doped nanocarbon cages is 3.523 cm³. 3 / g, micropore volume is 0.1cm³ 3 / g, accounting for 2.84% of the total pore volume; from the pore volume and pore size distribution curve, it can be seen that the micropore volume and pore size distribution curve has a distribution peak at 0.62nm, and the mesopore volume and pore size distribution curve has two distribution peaks at 3.94nm and 12.3nm, indicating that the sulfur-doped nano-carbon cage is a nano-carbon material with microporous structure and mesoporous structure.

[0118] Raman spectroscopy revealed that the sulfur-doped carbon nanocage exhibited distinct D and G peaks, I D / I G =1.005, indicating that the nano-carbon material has a certain degree of graphitization.

[0119] Preparation Example 2

[0120] (1) Precursor preparation: 30 g of nickel carbonate hydroxide, 50.37 g of citric acid and 27.8 g of potassium bisulfate were weighed according to the molar ratio of nickel source (calculated as nickel element), multi-component organic carboxylic acid and sulfur source of 1:1.2:1, and added into a beaker containing 50 mL of deionized water, stirred at 70°C to obtain a homogeneous solution, and continue to heat and evaporate to dryness to obtain a complex precursor material;

[0121] (2) Calcination: the complex precursor material was placed in a porcelain boat, then the porcelain boat was placed in the constant temperature zone of the tube furnace, nitrogen gas was introduced at a flow rate of 60 mL / min, and the temperature was raised to 600°C at a rate of 2.5°C / min, and after constant temperature for 2 h, the heating was stopped, and the temperature was cooled to room temperature under nitrogen atmosphere, to obtain a pyrolysis product;

[0122] (3) Acid washing: the pyrolysis product was added to 2.0 M aqueous HCl solution and stirred at 80°C for 10 h, then filtered, washed with deionized water until the filtrate was neutral, then the filter cake was dried at 140°C for 2 h to obtain sulfur-doped nanocarbon cage Z2.

[0123] The sulfur-doped nanocarbon cage was observed and measured by high-resolution transmission electron microscopy, and had a spherical or spherical-like morphology, and the diameter of the nanocarbon cage was 5-20 nm.

[0124] The mass percentage of carbon on the surface of the sulfur-doped nanocarbon cage was 86.89%, the mass percentage of oxygen was 10.35%, and the mass percentage of sulfur was 2.76% as measured by X-ray photoelectron spectroscopy (XPS).

[0125] The XPS S2p spectrum of the sulfur-doped nanocarbon cage had characteristic peaks of sulfur at 161±2 eV, 162-166 eV and 168±2 eV, and according to the peak area of the deconvoluted peak, the content of sulfur corresponding to the characteristic peak at 162-166 eV accounted for 79.6% of the total sulfur content.

[0126] The BET specific surface area of the sulfur-doped nanocarbon cage was 1096.314 m 2 / g, the micropore specific surface area was 186.416 m 2 / g, accounting for 17.0% of the total specific surface area; the total pore volume of the sulfur-doped nanocarbon cage was 2.761 cm 3 / g, the micropore volume was 0.087 cm 3 / g, accounting for 3.15% of the total pore volume; the micropore pore size distribution curve of the sulfur-doped nanocarbon cage had a distribution peak at 0.63 nm, and the mesopore pore size distribution curve had two distribution peaks at 3.7 nm and 10 nm, indicating that the sulfur-doped nanocarbon cage was a nanocarbon material with microporous structure and mesoporous structure.

[0127] The sulfur-doped nanocarbon cage has obvious D peak and G peak by Raman test, I D / I G =0.823, indicating that the nanocarbon material has a certain degree of graphitization.

[0128] Preparation Example 3

[0129] (1) Preparation of the precursor: according to the molar ratio of nickel source (calculated as nickel element), multi-component organic carboxylic acid and sulfur source of 1:0.7:1, 30 g of basic nickel carbonate, 29.4 g of citric acid and 24 g of sodium bisulfate were weighed into a beaker containing 100 mL of deionized water, and a homogeneous solution was obtained by stirring at 70°C, and the heating was continued to dry, to obtain a complex precursor material;

[0130] (2) Calcination: the complex precursor material was placed in a porcelain boat, and then the porcelain boat was placed in the constant temperature zone of the tube furnace, nitrogen was introduced at a flow rate of 300 mL / min, and the temperature was raised to 650°C at a rate of 5°C / min, and the heating was stopped after 2 h of constant temperature, and the temperature was cooled to room temperature under nitrogen atmosphere, to obtain a pyrolysis product;

[0131] (3) Acid washing: the pyrolysis product was added to 2.0 M HCl aqueous solution and stirred at 80°C for 8 h, then filtered, washed with deionized water until the filtrate was neutral, and then the filter cake was dried at 120°C for 2 h to obtain the sulfur-doped nanocarbon cage Z3.

[0132] The high-resolution transmission electron microscopy image of the sulfur-doped nanocarbon cage is shown in Figure 7 From Figure 7 it can be seen that the sulfur-doped nanocarbon cage has a spherical or spherical-like morphology, and the diameter of the nanocarbon cage is 10 nm.

[0133] The mass percentage of carbon on the surface of the sulfur-doped nanocarbon cage was 92.51% by X-ray photoelectron spectroscopy (XPS) determination, the mass percentage of oxygen was 5.36%, and the mass percentage of sulfur was 2.13%.

[0134] The XPS S2p spectrum of the sulfur-doped nanocarbon cage has characteristic peaks of sulfur at 161±2eV, 162-166eV and 168±2eV, and according to the peak area of the deconvoluted peak, it can be calculated that the sulfur content corresponding to the characteristic peak at 162-166eV accounts for 79.56% of the total sulfur content.

[0135] The BET specific surface area of the sulfur-doped nanocarbon cage was 678.217 m 2 / g by BET analysis, the micropore specific surface area was 124.5 m 2 / g, accounting for 18.3% of the total specific surface area; the total pore volume of the sulfur-doped nanocarbon cage was 1.742 cm 3 / g, the total micropore volume is 0.073 cm 3 / g, 4.2% of the total pore volume; the micropore volume pore size distribution curve of the sulfur-doped nanocarbon cage has a distribution peak at 0.63 nm, and the mesopore volume pore size distribution curve has two distribution peaks at 3.86 nm and 12.3 nm, indicating that the sulfur-doped nanocarbon cage is a nanocarbon material with microporous structure and mesoporous structure.

[0136] Raman test shows that the sulfur-doped nanocarbon cage has obvious D peak and G peak, I D / I G = 0.925, indicating that the nanocarbon material has a certain degree of graphitization.

[0137] Examples 1-8 and Comparative Examples 1-4 are used to illustrate the preparation of noble metal catalysts.

[0138] Example 1

[0139] Ru-based catalyst 10% Ru / C loaded with sulfur-doped nanocarbon cage was prepared by the initial wet impregnation method:

[0140] According to the mass of Ru, RuCl3 solution containing Ru 0.1 g and 10.0 mL of deionized water were mixed and stirred uniformly, then 0.9 g of sulfur-doped nanocarbon cage (Z1) obtained from Preparation Example 1 was added to the mixture, and after stirring and impregnating at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then dried in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading of Ru was 10% (mass percent). The precursor prepared in the above step was placed in a quartz tube, first calcined at 500°C for 4h in nitrogen, and then reduced at 500°C for 3h in a reducing atmosphere of 20% H2+80% N2, with a reducing atmosphere volume space velocity of 10h -1 , to obtain a noble metal catalyst A1 with a loading of 10% Ru / C (wherein the loading is based on the total amount of catalyst).

[0141] Example 2

[0142] According to the method of Example 1, RuCl3 solution containing Ru 0.05 g and 10 mL of deionized water were mixed and stirred uniformly according to the mass of Ru, then 0.95 g of sulfur-doped nanocarbon cage (Z1) obtained from Preparation Example 1 was added to the mixture, and after stirring and impregnating at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then dried in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading of Ru was 5% (mass percent). The precursor prepared in the above step was placed in a quartz tube, first calcined at 400°C for 6h in nitrogen, and then reduced at 400°C for 4h in a reducing atmosphere of 20% H2+80% N2, with a reducing atmosphere volume space velocity of 10h -1A precious metal catalyst A2 having a Ru loading of 5% by mass (where the loading is based on the total amount of the catalyst) was obtained.

[0143] Example 3

[0144] A catalyst precursor was obtained by mixing a RuCl3solution containing 0.15 g of Ru and 10 mL of deionized water by mass of Ru, stirring until uniform, and then adding 0.85 g of the sulfur-doped nanocarbon cage (Z1) obtained in Preparation Example 1 to the mixture, stirring to impregnate at room temperature for 10 hours, evaporating the water using a rotary evaporator, and then drying in an oven at 110°C for 12 hours. The Ru loading was 15% by mass. The precursor prepared in the above step was placed in a quartz tube, calcined at 600°C for 4 hours under nitrogen, and then reduced at 500°C for 4 hours under a reducing atmosphere of 20% by volume H2+80% by volume N2, with a reducing atmosphere volume space velocity of 20 h -1 A precious metal catalyst A3 having a Ru loading of 15% by mass (where the loading is based on the total amount of the catalyst) was obtained.

[0145] Example 4

[0146] A precious metal catalyst A4 having a Ru loading of 10% by mass (where the loading is based on the total amount of the catalyst) was obtained by the method of Example 1, except that the sulfur-doped nanocarbon cage (Z2) obtained in Preparation Example 2 was used as the carrier.

[0147] Example 5

[0148] A precious metal catalyst A5 having a Ru loading of 10% by mass (where the loading is based on the total amount of the catalyst) was obtained by the method of Example 1, except that the sulfur-doped nanocarbon cage (Z3) obtained in Preparation Example 3 was used as the carrier.

[0149] Example 6

[0150] Catalyst 5% Ru-5% Pt / C was prepared by incipient wetness impregnation:

[0151] A solution containing Ru 0.05 g of RuCl3and a solution containing Pt 0.05 g of H2PtCl6and 10.0 mL of deionized water were mixed by weighing each solution according to the mass of Ru and Pt, respectively, and stirring well, and then 0.9 g of the sulfur-doped nanocarbon cage (Zl) obtained in Preparation Example 1 was added to the mixture. After stirring and impregnating at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then drying was performed in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading amount of Ru was 5% by mass, and the loading amount of Pt was 5% by mass. The precursor prepared in the above procedure was placed in a quartz tube, calcined at 500°C for 4 hours in a nitrogen atmosphere, and reduced at 500°C for 3 hours in a reducing atmosphere of 20% by volume H2+80% by volume N2, at a volume space velocity of 10 h -1 , to obtain a supported 5% Ru-5% Pt / C noble metal catalyst A6 (wherein the loading amount is based on the total amount of the catalyst).

[0152] Example 7

[0153] A solution containing Ru 0.08 g of RuCl3and a solution containing Pt 0.02 g of H2PtCl6and 10.0 mL of deionized water were mixed by weighing each solution according to the mass of Ru and Pt, respectively, and stirring well, and then 0.9 g of the sulfur-doped nanocarbon cage (Zl) obtained in Preparation Example 1 was added to the mixture. After stirring and impregnating at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then drying was performed in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading amount of Ru was 8% by mass, and the loading amount of Pt was 2% by mass. The precursor prepared in the above procedure was placed in a quartz tube, calcined at 500°C for 4 hours in a nitrogen atmosphere, and reduced at 500°C for 3 hours in a reducing atmosphere of 20% by volume H2+80% by volume N2, at a volume space velocity of 10 h -1 , to obtain a supported 8% Ru-2% Pt / C noble metal catalyst A7 (wherein the loading amount is based on the total amount of the catalyst).

[0154] Example 8

[0155] A solution containing Ru 0.05 g of RuCl3and a solution containing Pd 0.05 g of PdCl2and 10.0 mL of deionized water were mixed according to the method of Example 6, and 0.9 g of the sulfur-doped nanocarbon cage (Z1) obtained in Preparation Example 1 was added thereto, and stirred to prepare a precursor. After impregnation at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then dried in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading amount of Ru was 5% by mass, and the loading amount of Pd was 5% by mass. The precursor prepared in the above step was placed in a quartz tube, calcined at 500°C for 4 hours in a nitrogen atmosphere, and then reduced at 500°C for 3 hours in a reducing atmosphere of 20% by volume H2+80% by volume N2, to obtain a supported 5% Ru-5% Pd / C noble metal catalyst A8 (wherein the loading amount is based on the total amount of the catalyst). -1 , to obtain a supported 5% Ru-5% Pd / C noble metal catalyst A8 (wherein the loading amount is based on the total amount of the catalyst).

[0156] Comparative Example 1

[0157] A solution containing Pt 0.1 g of H2PtCl6and 10 mL of deionized water were mixed according to the method of Example 1, and 0.9 g of the sulfur-doped nanocarbon cage (Z1) obtained in Preparation Example 1 was added thereto, and stirred to prepare a precursor. After impregnation at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then dried in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading amount of Pt was 10% by mass. The precursor prepared in the above step was placed in a quartz tube, calcined at 500°C for 4 hours in a nitrogen atmosphere, and then reduced at 500°C for 3 hours in a reducing atmosphere of 20% by volume H2+80% by volume N2, to obtain a catalyst D1 having a loading amount of 10% Pt / C (wherein the loading amount is based on the total amount of the catalyst).

[0158] Comparative Example 2

[0159] A solution containing Pd 0.1 g of PdCl2and 10 mL of deionized water were mixed according to the method of Example 1, and 0.9 g of the sulfur-doped nanocarbon cage (Z1) obtained in Preparation Example 1 was added thereto, and stirred to prepare a precursor. After impregnation at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then dried in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading amount of Pd was 10% by mass. The precursor prepared in the above step was placed in a quartz tube, calcined at 500°C for 4 hours in a nitrogen atmosphere, and then reduced at 500°C for 3 hours in a reducing atmosphere of 20% by volume H2+80% by volume N2, to obtain a catalyst D2 having a loading amount of 10% Pd / C (wherein the loading amount is based on the total amount of the catalyst).

[0160] Comparative Example 3

[0161] According to the method of Example 1, AuCl3solution containing Au 0.1 g and 10 mL of deionized water were weighed out by mass, stirred uniformly, and then 0.9 g of the sulfur-doped nanocarbon cage (Z1) obtained in Preparation Example 1 was added to the mixture. After stirring and impregnating at room temperature for 10 hours, the water was evaporated using a rotary evaporator, and then dried in an oven at 110°C for 12 hours to obtain a catalyst precursor. The loading amount of Au was 10% by mass. The precursor prepared in the above step was placed in a quartz tube, calcined at 500°C for 4 hours in nitrogen, and then reduced at 500°C for 3 hours in 20% H2+80% N2to obtain a 10% Au / C catalyst D3 (wherein the loading amount is based on the total amount of the catalyst).

[0162] Comparative Example 4

[0163] According to the method of Example 1, except that the support was changed to a commercially available Cabot VXC72 activated carbon product, a 10% Ru / C catalyst D4 (wherein the loading amount is based on the total amount of the catalyst) was obtained.

[0164] Test Examples 1 to 18 and Test Comparative Examples 1 to 4 were used to illustrate the preparation of 2,5-furandicarboxylic acid.

[0165] The conversion rate of 5-hydroxymethylfurfural and the yield of 2,5-furandicarboxylic acid were obtained by the following calculation formula:

[0166] The conversion rate of 5-hydroxymethylfurfural = (1 - the molar amount of 5-hydroxymethylfurfural remaining after the reaction / the molar amount of 5-hydroxymethylfurfural added before the reaction) x 100%.

[0167] The yield of 2,5-furandicarboxylic acid = the molar amount of 2,5-furandicarboxylic acid produced by the reaction / the molar amount of 5-hydroxymethylfurfural added before the reaction x 100%.

[0168] Test Example 1

[0169] In a 50 mL autoclave, 0.5 g of 5-hydroxymethylfurfural, 0.2 g of the A1 noble metal catalyst of Example 1, 10 g of a mixed solvent composed of 1,4-dioxane and water (mass ratio of 1:1), and water were added, the autoclave was closed, 1 MPa of oxygen was charged to replace the residual air in the autoclave, and the operation was repeated three times. Then, 1 MPa of oxygen was charged to the autoclave, the autoclave was placed on a heating furnace to heat to a reaction temperature of 100°C, and the reaction was performed at a rotation speed of 700 rpm for 10 hours. After the reaction, the autoclave was taken out of the heating furnace, cooled to room temperature, filtered, the filter cake was washed with the same mixed solvent as the reaction solvent, and finally diluted to 100 mL. A liquid sample was taken and analyzed by high performance liquid chromatography. The results of the reaction are shown in Table 1.

[0170] Test Example 2

[0171] The method of Test Example 1 was followed, except that 0.4 g of the A2 noble metal catalyst of Example 2 was used. The results of the reaction are shown in Table 1.

[0172] Test Example 3

[0173] The method of Test Example 1 was followed, except that 0.1 g of the A3 noble metal catalyst of Example 3 was used. The results of the reaction are shown in Table 1.

[0174] Test Example 4

[0175] The method of Test Example 1 was followed, except that 0.2 g of the A4 noble metal catalyst of Example 4 was used. The results of the reaction are shown in Table 1.

[0176] Test Example 5

[0177] The method of Test Example 1 was followed, except that 0.2 g of the A5 noble metal catalyst of Example 5 was used. The results of the reaction are shown in Table 1.

[0178] Test Example 6

[0179] The method of Test Example 1 was followed, except that 0.2 g of the A6 noble metal catalyst of Example 6 was used. The results of the reaction are shown in Table 1.

[0180] Test Example 7

[0181] The method of Test Example 1 was followed, except that 0.2 g of the A7 noble metal catalyst of Example 7 was used. The results of the reaction are shown in Table 1.

[0182] Test Example 8

[0183] The method of Test Example 1 was followed, except that 0.2 g of the A8 noble metal catalyst of Example 8 was used. The results of the reaction are shown in Table 1.

[0184] Test Example 9

[0185] The method of Test Example 1 was followed except that the oxygen pressure charged into the reactor at the start of the reaction was 2 MPa, and the results of the reaction are shown in Table 1.

[0186] Test Example 10

[0187] The method of Test Example 1 was followed except that the oxygen pressure charged into the reactor at the start of the reaction was 3 MPa, and the results of the reaction are shown in Table 1.

[0188] Test Example 11

[0189] The method of Test Example 1 was followed except that the reaction temperature was 120°C, and the results of the reaction are shown in Table 1.

[0190] Test Example 12

[0191] The method of Test Example 1 was followed except that the reaction temperature was 140°C, and the results of the reaction are shown in Table 1.

[0192] Test Example 13

[0193] The method of Test Example 1 was followed except that the reaction solvent was a mixed solvent composed of γ-valerolactone and water (mass ratio of γ-valerolactone to water: 1 : 1), and the total amount of the mixed solvent was 10 g, and the results of the reaction are shown in Table 2.

[0194] Test Example 14

[0195] The method of Test Example 1 was followed except that the reaction solvent was a mixed solvent composed of 1,4-dioxane and water (mass ratio of 1,4-dioxane to water: 3 : 1), and the total amount of the mixed solvent was 10 g, and the results of the reaction are shown in Table 2.

[0196] Test Example 15

[0197] The method of Test Example 1 was followed except that the reaction solvent was a mixed solvent composed of 1,4-dioxane and water (mass ratio of 1,4-dioxane to water: 0.5 : 1), and the total amount of the mixed solvent was 10 g, and the results of the reaction are shown in Table 2.

[0198] Test Example 16

[0199] The method of Test Example 1 was followed except that the reaction solvent was only water, and the total amount was 10 g, and the results of the reaction are shown in Table 2.

[0200] Test Example 17

[0201] The method of Test Example 1 was followed except that the reaction solvent was only 1,4-dioxane, and the total amount was 10 g, and the results of the reaction are shown in Table 2.

[0202] Test Example 18

[0203] According to the method of Test Example 1, except that the reaction solvent is only γ-valerolactone, the total amount is 10 g, and the reaction results are listed in Table 2.

[0204] Test Comparative Example 1

[0205] According to the method of Test Example 1, except that 0.2 g of D1 catalyst prepared in Test Comparative Example 1 is used, and other conditions are the same, the reaction results are listed in Table 1.

[0206] Test Comparative Example 2

[0207] According to the method of Test Example 1, except that 0.2 g of D2 catalyst prepared in Test Comparative Example 2 is used, and other conditions are the same, the reaction results are listed in Table 1.

[0208] Test Comparative Example 3

[0209] According to the method of Test Example 1, except that 0.2 g of D3 catalyst in Test Comparative Example 3 is used, and other conditions are the same, the reaction results are listed in Table 1.

[0210] Test Comparative Example 4

[0211] According to the method of Test Example 1, except that 0.2 g of D4 catalyst prepared in Test Comparative Example 4 is used, and other conditions are the same, the reaction results are listed in Table 1.

[0212] Table 1

[0213]

[0214]

[0215] Table 2

[0216]

[0217] According to the data in Table 1, 1. The noble metal catalyst obtained by using the specific sulfur-doped nanocarbon cage carrier to load the active component can realize efficient conversion of HMF to FDCA under alkali-free conditions under the conditions described in the method, and the yield of FDCA can be as high as 86%. 2. According to the data of Test Example and Test Comparative Examples 1-4, when the nitrogen-doped nanocarbon cage carrier is only loaded with Pt, Pd or Au active component to prepare an oxidation catalyst, the catalytic performance is obviously lower than that of the Ru-based oxidation catalyst loaded on the nitrogen-doped nanocarbon cage, which shows that the Ru-based oxidation catalyst loaded on the high specific surface area nitrogen-doped nanocarbon cage involved in the present application has special catalytic effect on the reaction of HMF oxidation to FDCA.

[0218] According to the data in Table 2, it can be known from the data of test examples 13-15 and test examples 16-18 that the reaction process of preparing FDCA by oxidizing HMF can be better realized in the limited range of the application by using the mixed solvent composed of water and 1,4-dioxane or γ-valerolactone, the noble metal catalyst has higher activity, and the yield of FDCA is higher.

[0219] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and belong to the protection scope of the application.

Claims

1. A noble metal catalyst, wherein, The catalyst comprises a sulfur-doped carbon nanocage and an active component supported on the sulfur-doped carbon nanocage, wherein the active component is Ru; the sulfur-doped carbon nanocage has a microporous structure and a mesoporous structure, wherein the BET specific surface area of ​​the sulfur-doped carbon nanocage is 500-1600 m². 2 / g, the proportion of the specific surface area within the micropores to the total specific surface area is less than 20%; the total pore volume of the sulfur-doped nanocarbon cage is greater than 1.4 cm³. 3 / g, the proportion of micropore volume to total pore volume is greater than or equal to 2.84% and less than 10%; the mass percentage of carbon on the surface of the sulfur-doped carbon nanocage, as determined by X-ray photoelectron spectroscopy, is 84-95%, and the mass percentage of sulfur is 0.2-5%. The preparation method of sulfur-doped carbon nanocages includes the following steps: A. Precursor preparation: A homogeneous solution containing a nickel source, a polycarboxylic acid, a sulfur source and a solvent is provided, and then the solvent is removed from the homogeneous solution to obtain a complex precursor, wherein the sulfur source is selected from group IA hydrogen sulfate and / or sulfate. B. Calcination: Under an inert atmosphere, the complex precursor obtained in step A is calcined at a constant temperature of 450-700℃ to obtain the pyrolysis product. C. Acid washing: Provide an aqueous solution containing the pyrolysis product obtained in step B, and react it with acid, then separate the solid and liquid, wash and dry.

2. The catalyst according to claim 1, wherein, Based on the total amount of catalyst, the content of the sulfur-doped nano-carbon cage is 70-99% by mass, and the content of the active component by element is 1-30% by mass.

3. The catalyst according to claim 2, wherein, Based on the total amount of catalyst, the content of the sulfur-doped nano-carbon cage is 85-95% by mass, and the content of the active component by element is 5-15% by mass.

4. The catalyst according to claim 1 or 2, wherein, In the pore size distribution curve of the sulfur-doped carbon nanocage, there is a micropore distribution peak at 0.59-0.63 nm, and two mesopore distribution peaks at 2.73-4.1 nm and 3.877-15.6 nm. Alternatively, the sulfur-doped carbon nanocage has a spherical or near-spherical morphology.

5. The catalyst according to claim 1 or 2, wherein, The diameter of the sulfur-doped carbon nanocage is 2-200 nm.

6. The catalyst according to claim 5, wherein, The diameter of the sulfur-doped carbon nanocage is 3-50 nm.

7. The catalyst according to claim 1 or 2, wherein, In the Raman curve of the sulfur-doped carbon nanocage, I D / I G The range is 0.5-1.

5.

8. The catalyst according to claim 7, wherein, In the Raman curve of the sulfur-doped carbon nanocage, I D / I G The range is 0.5-1.

1.

9. The catalyst according to claim 1 or 2, wherein, Based on the total amount of sulfur on the surface of the sulfur-doped carbon nanocage, the mass percentage of sulfur in the X-ray photoelectron spectrum of the sulfur-doped carbon nanocage is determined to be 2-90% by the characteristic spectral peaks corresponding to 162-166 eV.

10. The catalyst according to claim 9, wherein, Based on the total amount of sulfur on the surface of the sulfur-doped carbon nanocage, the mass percentage of sulfur in the X-ray photoelectron spectrum of the sulfur-doped carbon nanocage is determined to be 70-88% by the characteristic spectral peaks corresponding to 162-166 eV.

11. A method for preparing the noble metal catalyst according to any one of claims 1-10, wherein, The method includes: S1. After introducing the active component into the sulfur-doped nano-carbon cage, the sample is dried to obtain the catalyst precursor. S2. The catalyst precursor obtained in step S1 is calcined in a calcining atmosphere and then treated in a reducing atmosphere to obtain a noble metal catalyst. The preparation method of sulfur-doped carbon nanocages includes the following steps: A. Precursor preparation: A homogeneous solution containing a nickel source, a polycarboxylic acid, a sulfur source and a solvent is provided, and then the solvent is removed from the homogeneous solution to obtain a complex precursor, wherein the sulfur source is selected from group IA hydrogen sulfate and / or sulfate. B. Calcination: Under an inert atmosphere, the complex precursor obtained in step A is calcined at a constant temperature of 450-700℃ to obtain the pyrolysis product. C. Acid washing: Provide an aqueous solution containing the pyrolysis product obtained in step B, and react it with acid, then separate the solid and liquid, wash and dry.

12. The method according to claim 11, wherein, In step A, the nickel source is selected from at least one of organic acid salts, carbonates and basic carbonates containing nickel. And / or, the sulfur source is selected from at least one of potassium sulfate, sodium sulfate, potassium bisulfate, and sodium bisulfate; And / or, the polycarboxylic acid is selected from at least one of citric acid, maleic acid, trimesic acid, terephthalic acid and malic acid; And / or, the solvent is water and / or ethanol.

13. The method according to claim 12, wherein, In step A, the nickel source is a carbonate and / or basic carbonate containing nickel.

14. The method according to claim 12, wherein, The sulfur source is potassium hydrogen sulfate.

15. The method according to claim 12, wherein, The polycarboxylic acid is citric acid and / or terephthalic acid.

16. The method according to any one of claims 11-15, wherein, In step A, the molar ratio of the nickel source, the poly-organic carboxylic acid and the sulfur source, calculated as nickel element, is 1:0.1-10:0.1-2.

17. The method according to claim 16, wherein, In step A, the molar ratio of the nickel source, the poly-organic carboxylic acid, and the sulfur source, calculated as nickel element, is 1:0.5-3:0.3-2.

18. The method according to claim 17, wherein, In step A, the molar ratio of the nickel source, the poly-organic carboxylic acid and the sulfur source, calculated as nickel element, is 1:0.7-1.5:0.5-1.

2.

19. The method according to any one of claims 11-15, wherein, In step B, the temperature of the constant-temperature calcination is 500-650℃; And / or, the conditions for the isothermal calcination include: a heating rate of 0.5-30℃ / min and an isothermal time of 20-600min.

20. The method according to claim 19, wherein, The conditions for constant temperature calcination include: a heating rate of 1-10℃ / min and a constant temperature time of 60-480min.

21. The method according to any one of claims 11-15, wherein, In step C, the acid is an aqueous solution of an inorganic acid and / or an aqueous solution of an organic acid; And / or, in step C, the aqueous solution of the pyrolysis product is reacted with acid at a temperature of 20-120°C for a time of 0.1-48 h.

22. The method according to claim 21, wherein, In step C, the acid is one or more of hydrochloric acid aqueous solution, sulfuric acid aqueous solution, nitric acid aqueous solution and citric acid aqueous solution.

23. The method according to claim 22, wherein, In step C, the acid is an aqueous solution of hydrochloric acid.

24. The method according to claim 21, wherein, In step C, the aqueous solution of the pyrolysis product is reacted with acid at a temperature of 60-100℃ for 4-12 hours.

25. The method according to any one of claims 11-15, wherein, In step S1, the drying conditions include: a temperature of 80-120℃ and a time of 8-20h.

26. The method according to any one of claims 11-15, wherein, In step S2, the calcination atmosphere is at least one selected from nitrogen, argon, neon and helium; And / or, the reducing atmosphere is hydrogen and optionally an inert gas.

27. The method according to any one of claims 11-15, wherein, The calcination conditions include: a temperature of 300-800℃ and a time of 2-8 hours.

28. The method according to claim 27, wherein, The calcination conditions include: a temperature of 400-600℃ and a time of 3-6 hours.

29. The method according to any one of claims 11-15, wherein, The processing conditions under the reducing atmosphere include: a temperature of 200-600℃, a time of 1-5 hours, and a volume hourly space velocity (VHSV) of 1-100 h⁻¹. -1 .

30. The method according to claim 29, wherein, The processing conditions under the reducing atmosphere include: a temperature of 300-500℃, a time of 2-4 hours, and a volume hourly space velocity (VHSV) of 5-50 h⁻¹. -1 .

31. The use of the noble metal catalyst according to any one of claims 1-10 in the preparation of 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural.

32. A method for preparing 2,5-furandicarboxylic acid, wherein, The method comprises: reacting 5-hydroxymethylfurfural with an oxygen-containing gas in the presence of a noble metal catalyst and a mixed solvent as described in any one of claims 1-10 to obtain 2,5-furandicarboxylic acid; The mixed solvent is a mixture of organic solvent and water.

33. The method according to claim 32, wherein, The organic solvent is selected from at least one of tetrahydrofuran, 1,4-dioxane, γ-valerolactone and dimethyl sulfoxide; And / or, in the mixed solvent, the mass ratio of organic solvent to water is 10:1 to 0.1:

1.

34. The method according to claim 33, wherein, The organic solvent is 1,4-dioxane.

35. The method according to claim 33, wherein, In the mixed solvent, the mass ratio of organic solvent to water is 4:1 to 0.4:

1.

36. The method according to any one of claims 32-35, wherein, Based on the total volume of the solution formed by the 5-hydroxymethylfurfural and the mixed solvent, the content of the 5-hydroxymethylfurfural is 0.1-20% by mass. And / or, the molar ratio of the active component to 5-hydroxymethylfurfural in the noble metal catalyst is 1:1-1000; And / or, the oxygen-containing gas is selected from pure oxygen, air, and a mixture of oxygen and an inert gas; And / or, the partial pressure of the oxygen-containing gas is 0.5-5 MPa; And / or, the reaction temperature is 50-170℃ and the time is 4-40h.

37. The method according to claim 36, wherein, Based on the total amount of the solution formed by the 5-hydroxymethylfurfural and the mixed solvent, the content of the 5-hydroxymethylfurfural is 0.5-15% by mass.

38. The method according to claim 37, wherein, Based on the total amount of the solution formed by the 5-hydroxymethylfurfural and the mixed solvent, the content of the 5-hydroxymethylfurfural is 1-10% by mass.

39. The method according to claim 36, wherein, The molar ratio of the active component to 5-hydroxymethylfurfural in the noble metal catalyst is 1:5-250.

40. The method according to claim 39, wherein, The molar ratio of the active component to 5-hydroxymethylfurfural in the noble metal catalyst is 1:5-35.

41. The method according to claim 36, wherein, The partial pressure of the oxygen-containing gas is 1-3 MPa.

42. The method according to claim 36, wherein, The reaction temperature is 90-150℃ and the time is 6-20h.

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