Photocatalyst for preparing bio-based 2,5-furandicarboxylic acid and its preparation

Abstract

The present invention relates to a photocatalyst for preparing bio-based 2,5-furandicarboxylic acid, which comprises a carrier and an active component loaded on the carrier; the active component is a transition metal M oxide MO x and Au nanoparticles, the transition metal M is one or more of Fe, Co and Ni, and the carrier includes one or more of active titanium dioxide, cerium dioxide and g-C3N4; the catalyst has high catalytic activity, high stability and good reaction performance. The present invention also relates to a method for preparing 2,5-furandicarboxylic acid by oxidizing 5-hydroxymethylfurfural using the above-mentioned photocatalyst, which has the advantages of short reaction path, high selectivity, few by-products and green environmental protection.

Description

Technical Field

[0001] The invention belongs to the field of catalyst preparation and application, and relates to a photocatalyst for preparing bio-based 2,5-furandicarboxylic acid, and a preparation method and application thereof. Background Art

[0002] With the rapid development of the global economy, the consumption of natural energy is increasing, and finding alternative clean energy has become a research focus. Biomass comes from nature and is one of the most abundant renewable resources in the world. 5-Hydroxymethylfurfural (HMF) is considered to be a chemical with great value prepared from biomass, which can be converted into other derivatives through oxidation-reduction, hydrolysis, etc. Among them, 2,5-furandicarboxylic acid (FDCA), as its oxidation product, was listed as one of the twelve bio-based platform chemicals by the U.S. Department of Energy in 2004. Due to the particularity of its molecular structure, it can be used as an alternative material to produce polyamide, etc., greatly reducing environmental pollution.

[0003] Due to its good development prospects and market value, the preparation method of FDCA has received extensive attention, and most of the research is based on HMF. The catalytic process includes traditional thermal catalytic oxidation, high temperature, high pressure and high energy consumption. Therefore, finding a more environmentally friendly photocatalytic oxidation method to obtain high-yield FDCA is the most urgent issue at present.

[0004] Patent CN113351210A discloses a Cu-based catalyst, the chemical formula of which is Cu / CoAlO, and a xenon lamp is used as a light source to oxidize and obtain a product. Although the reaction time is short, the use of high-purity Ar to replace the air in the reaction bottle during the reaction is too costly. Patent CN106925262A discloses a supported catalyst, the carrier of which is graphene, silicon carbide, aluminum oxide, etc., and the active metal components are gold, palladium, platinum, silver, etc. The light source used is sunlight or artificially simulated sunlight. However, the reaction system needs to be heated to 200°C, which is a high temperature. Patent CN113698373A discloses a method of using Cu2O crystals as a catalyst, which is a p-type semiconductor and uses a daylight xenon lamp as a light source, but the reaction time is as long as 12-20h. Patent CN109503529A discloses a ring-shaped catalyst, the light source is a blue light-emitting diode lamp, the catalytic time is 24-36h, the reaction time is long, and it is not conducive to energy saving and environmental protection. Patent CN109107605A discloses a decaprolactone ammonium salt using tetramethyl quaternary ammonium salt, tetraethyl quaternary ammonium salt, tetrapropyl quaternary ammonium salt, and tetrabutyl quaternary ammonium salt as cations as catalyst, pure oxygen as oxidant, acetonitrile as solvent, and hydrochloric acid as acidic promoter. The reaction system is relatively complex, and the yield of the target product FDCA is low.

[0005] Therefore, researchers are eager to obtain an efficient catalyst that can be used in HMF oxidation reactions with mild reaction conditions and short reaction time. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a photocatalyst for preparing bio-based 2,5-furandicarboxylic acid in view of the deficiencies of the prior art, wherein the photocatalyst can achieve high conversion rate and selectivity in a relatively short time.

[0007] The present invention also provides a method for preparing the photocatalyst. The method has simple process and the prepared photocatalyst has good stability and high activity.

[0008] The present invention also provides the use of the photocatalyst in preparing 2,5-furandicarboxylic acid by photocatalytic oxidation of 5-hydroxymethylfurfural.

[0009] To this end, the first aspect of the present invention provides a high-efficiency photocatalyst for preparing bio-based 2,5-furandicarboxylic acid, which is composed of a carrier and an active component loaded on the carrier; the active component is a transition metal M oxide MO x and Au nanoparticles, wherein the transition metal M is one or more of Fe, Co and Ni; the photocatalyst may also be represented by MO in the present invention. x -Au / carrier-supported photocatalyst.

[0010] The inventors have found that transition metal M oxide MO x and Au nanoparticles as active components, and the prepared photocatalyst for preparing bio-based 2,5-furandicarboxylic acid has high activity and good stability.

[0011] In some embodiments of the present invention, the carrier includes one or more of active titanium dioxide, cerium dioxide and g-C3N4; the research results show that the above carrier is used to load the transition metal M oxide MO x and Au nanoparticles, and the prepared photocatalyst for preparing bio-based 2,5-furandicarboxylic acid has high activity and good selectivity.

[0012] According to the present invention, in the catalyst, Au nanoparticles and transition metal oxide MO x The mass ratio is 1:(0.1-30), preferably 1:(1-20).

[0013] In some embodiments of the present invention, the loading amount of the Au nanoparticles is 0.01 wt%-2 wt%, preferably 0.5 wt%-1 wt%.

[0014] In other embodiments of the present invention, the transition metal oxide MO xThe loading amount is 0.001 wt%-60 wt%, more preferably 0.5 wt%-20 wt%.

[0015] The second aspect of the present invention provides a method for preparing a photocatalyst for preparing 2,5-furandicarboxylic acid as described in the first aspect of the present invention, comprising:

[0016] Step A, mixing deionized water, a carrier, and tetrachloroauric acid uniformly to form a mixed solution containing gold;

[0017] Step B, heating the gold-containing mixed solution in a constant temperature water bath under continuous stirring, washing with deionized water to remove chloride ions, and drying after washing to obtain a dry photocatalyst precursor;

[0018] Step C, adding deionized water and M compound to the dried photocatalyst precursor, stirring at a constant temperature, drying and then calcining to obtain a finished catalyst product.

[0019] In some embodiments of the present invention, in step A, the mass ratio of water to carrier is 1:(1-200), preferably 1:(50-150).

[0020] In other embodiments of the present invention, the mass fraction of tetrachloroauric acid relative to the carrier is 0.01%-2%, preferably 0.5%-1%, calculated as gold ions.

[0021] In the present invention, the M compound is one or more of ferric nitrate nonahydrate, cobalt nitrate hexahydrate and nickel nitrate hexahydrate.

[0022] In some embodiments of the present invention, in step C, the mass fraction of the M compound relative to the carrier is expressed as x The amount is calculated to be 0.001%-60%, preferably 0.5%-20%.

[0023] According to the present invention, in step B, the heating temperature is 10-200°C, preferably 20-150°C.

[0024] According to the present invention, in step B, the heating time is 0.5-10 h, preferably 1-8 h.

[0025] There is no particular limitation on the number of times of washing with deionized water in the present invention, as long as the chloride ions can be removed to the maximum extent; for example, in some examples of the present invention, in step B, the number of times of washing with deionized water is 2-20 times, preferably 3-15 times.

[0026] In other embodiments of the present invention, in step B, the drying temperature is 30-150°C, preferably 40-120°C.

[0027] In some embodiments of the present invention, in step C, the calcination temperature is 50-750°C, preferably 100-600°C.

[0028] In other embodiments of the present invention, in step C, the calcination time is 0.5h-10h, preferably 1h-8h.

[0029] The third aspect of the present invention provides the use of the photocatalyst as described in the first aspect of the present invention or the photocatalyst prepared by the preparation method as described in the second aspect of the present invention in the photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to prepare 2,5-furandicarboxylic acid (FDCA), which can be understood as a method for preparing 2,5-furandicarboxylic acid by photocatalytic oxidation of 5-hydroxymethylfurfural using the photocatalyst as described in the first aspect of the present invention or the photocatalyst prepared by the preparation method as described in the second aspect of the present invention, and the method has excellent catalytic activity, high selectivity and few by-products.

[0030] The reaction pathway for preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural is as follows Figure 1 As shown. In Route B, the hydroxyl group (-OH) of 5-hydroxymethylfurfural is oxidized to the aldehyde group (-CHO), which requires dehydrogenation oxidation; while in Route A, the aldehyde group (-CHO) of 5-hydroxymethylfurfural is oxidized to the carboxyl group (-COOH), which is obtained by oxygen oxidation. The inventors have found that the reaction pathway for preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural using the photocatalyst provided by the present invention is as follows: Figure 1 As shown in Route A, the oxidation of the functional groups in Route A is easier than that in Route B.

[0031] According to the present invention, the application includes: mixing 5-hydroxymethylfurfural with a solvent, adding a catalyst, adding an alkaline substance, and reacting under stirring conditions, room temperature, and LED lighting.

[0032] In the present invention, the solvent is deionized water.

[0033] In some embodiments of the present invention, the mass ratio of the alkaline substance to 5-hydroxymethylfurfural is 1:(0.5-10), preferably 1:(1-8).

[0034] In some embodiments of the present invention, the mass ratio of 5-hydroxymethylfurfural to solvent is 1:(50-300), preferably 1:(100-280).

[0035] In some embodiments of the present invention, the mass ratio of 5-hydroxymethylfurfural to catalyst is 1:(0.1-5), preferably 1:(0.5-4).

[0036] In some embodiments of the present invention, the alkaline substance is at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0037] In some embodiments of the present invention, the reaction time is 0.5-10 h, preferably 1-6 h.

[0038] In the present invention, MO is used x -Au / carrier-supported photocatalyst oxidizes 5-hydroxymethylfurfural to prepare 2,5-furandicarboxylic acid. The study found that the key active oxygen species affecting the oxidation of 5-hydroxymethylfurfural are singlet oxygen 1O2 and superoxide radicals·O2 generated by the adsorption of O2 by the photocatalyst. - .

[0039] Further research results show that the catalyst is used in the preparation of 2,5-furandicarboxylic acid. After 0-1h of reaction, the conversion rate can reach more than 80%, the selectivity can reach 80%, and after the reaction is completed, the conversion rate can reach 100% and the selectivity can reach 99%. The catalyst has excellent catalytic oxidation performance.

[0040] The term "water" in the present invention, unless otherwise specified or limited, refers to deionized water, distilled water or ultrapure water.

[0041] The term "supported catalyst" used in the present invention refers to a catalyst in which the active components and the co-catalyst are uniformly dispersed and supported on a specially selected carrier.

[0042] Compared with the existing technology, the photocatalyst provided by the present invention has the following advantages:

[0043] (1) The reaction conditions of the present invention are mild, the reaction temperature does not exceed 40° C., and the reaction time does not exceed 8 h, which breaks through the traditional high temperature and high pressure reaction conditions.

[0044] (2) The light source used in the illumination of the present invention is visible light, which is green and environmentally friendly. 2,5-furandicarboxylic acid can be prepared with high selectivity, the conversion rate of 5-hydroxymethylfurfural is basically completely converted, the selectivity is close to 100%, and there are few by-products, which has good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be further described in detail below in conjunction with the accompanying drawings:

[0046] Figure 1 The reaction pathway for preparing 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural is shown. DETAILED DESCRIPTION

[0047] To make the present invention easy to understand, the present invention will be described in detail below in conjunction with the accompanying drawings. However, before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described. It should also be understood that the terms used herein are only for describing specific embodiments and are not intended to be limiting.

[0048] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, preferred methods and materials are now described.

[0049] Example

[0050] The present invention is described in detail below through specific examples. The experimental methods described below, unless otherwise specified, are all routine laboratory methods. The experimental materials described below, unless otherwise specified, can all be obtained from commercial channels.

[0051] In the present invention, the contents of the reaction solution and the product are quantified by high performance liquid chromatography, the mobile phase is dilute sulfuric acid, and the conversion rate (Conversion) of the reactant and the yield (Yield) and selectivity (Selectivity) of the product are calculated by comparing the standard curve.

[0052]

[0053] In formula (I):

[0054] c HMF initial is the initial concentration of 5-hydroxymethylfurfural added, in g / L.

[0055] c HMF final It is the concentration of 5-hydroxymethylfurfural after the oxidation reaction is completed, in g / L.

[0056]

[0057] In formula (II):

[0058] c HMF inictal is the initial concentration of 5-hydroxymethylfurfural added, in g / L.

[0059] c X final It is the concentration of the target product measured after the oxidation reaction is completed, in g / L.

[0060]

[0061] In formula (III):

[0062] Yield is the calculation result of formula (II).

[0063] Conversion is the calculation result of formula (I).

[0064] Embodiment 1:

[0065] 1. Preparation of photocatalyst

[0066] (1) mixing deionized water, carrier TiO2, and tetrachloroauric acid uniformly to form a gold-containing mixed solution;

[0067] (2) The gold-containing mixed solution was heated in a water bath at a constant temperature of 50° C. for 5 h under continuous stirring, and then washed 8 times with deionized water. After washing, the mixed solution was placed in a forced air drying oven for drying to obtain a dry photocatalyst precursor;

[0068] (3) adding deionized water and ferric nitrate nonahydrate to the dried photocatalyst precursor, stirring at a constant temperature of 40° C. for 3 h, and calcining at 150° C. for 5 h after drying to obtain a finished catalyst;

[0069] In the above-mentioned process of preparing the photocatalyst, the mass ratio of water to carrier TiO2 is 120:1; the mass fraction of tetrachloroauric acid added to the carrier TiO2 is 1%; and the mass fraction of ferric nitrate added to the carrier TiO2 is 15%.

[0070] 2. Preparation of 2,5-furandicarboxylic acid

[0071] 5-Hydroxymethylfurfural was dissolved in deionized water, and the catalyst and NaOH were added into a photocatalytic reactor. The magnetic stirring speed was 400 rpm. After stirring in the dark for 30 minutes, the reaction mixture was irradiated with visible light for 4 hours to obtain a reaction mixture.

[0072] In the above process of preparing 2,5-furandicarboxylic acid, the mass ratio of NaOH to 5-hydroxymethylfurfural is 1:3, the volume (ml) ratio of 5-hydroxymethylfurfural to deionized water is 1:200, and the mass ratio of 5-hydroxymethylfurfural to the catalyst is 1:1;

[0073] The yield of 2,5-furandicarboxylic acid in the reaction mixture was detected by HPLC, and the detection conditions were as follows: the mobile phase was sulfuric acid, the column temperature was 30°C, the flow rate was 0.5 ml / min, and the column was HPX-87. The results of the HPLC standard curve determination and the tests and calculations based on formulas (I), (II) and (III) showed that the conversion rate of 5-hydroxymethylfurfural was 100%, the yield of 2,5-furandicarboxylic acid was 99%, and the selectivity was 99%.

[0074] Embodiment 2:

[0075] This embodiment is different from Embodiment 1 in that:

[0076] After the catalyst precursor is reduced, hexahydrated cobalt nitrate is added. The mass fraction of cobalt nitrate added relative to the amount of carrier TiO2 is 15%. The remaining reaction conditions are the same as those in Example 1.

[0077] The results of the HPLC standard curve determination and the tests and calculations based on formulas (I), (II) and (III) showed that the conversion rate of 5-hydroxymethylfurfural was 100%, the yield of 2,5-furandicarboxylic acid was 99%, and the selectivity was 99%.

[0078] Embodiment 3:

[0079] This embodiment is different from Embodiment 1 in that:

[0080] After the catalyst precursor is reduced, nickel nitrate hexahydrate is added. The mass fraction of nickel nitrate added relative to the amount of carrier TiO2 is 15%. The remaining reaction conditions are the same as in Example 1.

[0081] The results of the HPLC standard curve determination and the tests and calculations based on formulas (I), (II) and (III) showed that the conversion rate of 5-hydroxymethylfurfural was 100%, the yield of 2,5-furandicarboxylic acid was 99%, and the selectivity was 99%.

[0082] Embodiment 4:

[0083] This embodiment is different from Embodiment 1 in that:

[0084] The carrier used in preparing the catalyst is CeO2, and the other addition amounts and reaction conditions are the same as those in Example 1. The conversion rate of 5-hydroxymethylfurfural, the yield of 2,5-furandicarboxylic acid, and the selectivity are 99%, as determined by HPLC standard curve determination and testing and calculation based on formulas (I), (II) and (III).

[0085] Embodiment 5:

[0086] This embodiment is different from Embodiment 1 in that:

[0087] The carrier used in preparing the catalyst was g-C3N4, and the other addition amounts and reaction conditions were the same as those in Example 1. The conversion rate of 5-hydroxymethylfurfural was 100%, the yield of 2,5-furandicarboxylic acid was 99%, and the selectivity was 99%, as determined by HPLC standard curve determination and testing and calculation based on formulas (I), (II) and (III).

[0088] Embodiment 6:

[0089] This embodiment is different from Embodiment 1 in that:

[0090] The NaOH added in the reaction was replaced with K2CO3, and the other reaction conditions were the same as those in Example 1.

[0091] The results of the HPLC standard curve determination and the tests and calculations based on formulas (I), (II) and (III) showed that the conversion rate of 5-hydroxymethylfurfural was 100%, the yield of 2,5-furandicarboxylic acid was 99%, and the selectivity was 99%.

[0092] It should be noted that the embodiments described above are only preferred embodiments of the present invention, which are used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for preparing a photocatalyst for preparing 2,5-furandicarboxylic acid, characterized in that: The preparation method comprises: Step A, mixing deionized water, a carrier, and tetrachloroauric acid uniformly to form a mixed solution containing gold; Step B, heating the gold-containing mixed solution in a constant temperature water bath under continuous stirring, washing with deionized water to remove chloride ions, and drying after washing to obtain a dry photocatalyst precursor; Step C, adding deionized water and compound M to the dried photocatalyst precursor, stirring at a constant temperature, drying and then calcining to obtain a finished catalyst product; The mass fraction of tetrachloroauric acid relative to the carrier is 0.5%-1% calculated as gold ions; The M compound is one or more of ferric nitrate nonahydrate, cobalt nitrate hexahydrate and nickel nitrate hexahydrate.

2. The preparation method according to claim 1, characterized in that: In step C, the mass fraction of the M compound relative to the carrier is expressed as x It is calculated as 0.5%-20%.

3. The preparation method according to claim 1, characterized in that In step B, the heating temperature is 50-150°C; and / or, the heating time is 1-8 hours; and / or, the drying temperature is 40-120°C.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step C, the calcination temperature is 100-600°C; and / or, the calcination time is 1 h-8 h; and / or, the constant temperature stirring temperature is 30-50°C; and / or, the constant temperature stirring time is 0.5 h-5 h.

5. The photocatalyst prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The photocatalyst is composed of a carrier and an active component loaded on the carrier; the active component is a transition metal M oxide MO x and Au nanoparticles, wherein the transition metal M is one or more of Fe, Co and Ni.

6. The photocatalyst according to claim 5, characterized in that The carrier includes one or more of active titanium dioxide, cerium dioxide and g-C3N4; and / or, in the catalyst, Au nanoparticles and transition metal oxide MO x The mass ratio is 1: (1-20); the loading amount of the Au nanoparticles is 0.5wt%-1wt%, and the transition metal oxide MO x The loading amount is 0.5wt%-20wt%.

7. Use of the photocatalyst prepared by the preparation method according to any one of claims 1 to 4 or the photocatalyst according to claim 5 or 6 in the preparation of 2,5-furandicarboxylic acid by photocatalytic oxidation of 5-hydroxymethylfurfural.

8. The use according to claim 7, characterized in that: The application comprises: mixing 5-hydroxymethylfurfural with a solvent, adding a catalyst, adding an alkaline substance, and reacting under stirring conditions, room temperature, and LED lighting.

9. The use according to claim 8, characterized in that: The mass ratio of the alkaline substance to 5-hydroxymethylfurfural is 1:(1-8); and / or the mass ratio of 5-hydroxymethylfurfural to the solvent is 1:(100-280); and / or the mass ratio of 5-hydroxymethylfurfural to the catalyst is 1:(0.5-4).

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