The invention relates to 5, 5apos; preparation method of-[oxybis (methylene)] bis [2-furancarboxylic acid] compound

Abstract

The invention discloses a preparation method of a 5, 5 '-[oxygen bis (methylene)] bis [2-barking formic acid] compound. The preparation method comprises the following steps: forming a mixed system containing bis-(5-formylshadberry) acyl, a supported noble metal catalyst, a first alkaline reagent and water, and carrying out an oxidation reaction in an oxygen atmosphere to obtain the 5, 5 '-[oxygen bis (methylene)] bis [2-barking formic acid] compound, wherein the supported noble metal catalyst comprises an active metal and a carrier, and the halo fraction of the active metal in the supported noble metal catalyst is 0.1%-5%. According to the preparation method, the high-yield 5, 5 '-[oxygen bis (methylene)] bis [2-barking formic acid] compound can be obtained through catalytic oxidation of bis-(5-formylshadberry group) under mild conditions, and the supported noble metal catalyst can be highly catalytically recycled, so that the energy consumption of equipment can be greatly reduced, the reaction cost can be reduced, and the method is green and economical.

Description

Technical Field

[0001] The invention belongs to the technical field of biomass multiphase catalytic conversion, and specifically relates to a method for preparing a 5,5'-[oxybis(methylene)]bis[2-furancarboxylic acid] compound. Background Art

[0002] Using biomass resources as raw materials to produce petroleum-based chemicals, polymer materials, and chemical intermediates has become an important topic in the sustainable chemical industry. It can effectively alleviate global warming and reduce environmental pollution, and is in line with the concept of green and sustainable development. 5-Hydroxymethylfurfural (HMF) extracted from biomass can undergo oxidation, hydrogenation, esterification and other reactions to derive a series of chemicals. 2,5-Furan dimethanol (FDCA) prepared by oxidation of HMF is considered to be a very promising renewable bio-based monomer compound that can replace traditional non-renewable fossil resources PET plastic to prepare PEF polyester, thereby achieving green recycling and renewable utilization. 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] (OBMFCA) has a larger molecular weight than FDCA, which means that the formed polymer will have better mechanical properties and thermal stability. Therefore, it is of great significance to develop products based on biomass resources to replace petroleum-based polymers.

[0003] Bis-(5-formylfurfuryl) ether (OBMF) is formed by the self-etherification of two HMF molecules and can be used to prepare polymer products with high electrical and thermal conductivity. However, due to its higher molecular weight, OBMF has poor water solubility compared to HMF, which makes the oxidation process of its side chain aldehyde group not as simple as HMF oxidation. Among them, supported precious metal catalysts are widely used because they can significantly promote the occurrence of the reaction, improve catalytic activity and product yield. However, there is no research report on the preparation of OBMFCA compounds using OBMF. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing 5,5'-[oxybis(methylene)]bis[2-furancarboxylic acid] compound to overcome the shortcomings of the prior art.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0006] One aspect of the present invention provides a method for preparing a 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound, comprising: forming a first mixed system comprising bis-(5-formylfurfuryl) ether, a supported noble metal catalyst, a first alkaline reagent and water, and performing an oxidation reaction in an oxygen atmosphere to obtain the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound; wherein the supported noble metal catalyst comprises an active metal and a carrier, the active metal comprises at least any one of platinum, gold, iridium, palladium, ruthenium and silver, the carrier comprises at least any one of TiO2, CeO2, HAP and Mn3O4, and the mass fraction of the active metal in the supported noble metal catalyst is 0.1% to 5%.

[0007] Compared with the prior art, the present invention has at least the following beneficial effects:

[0008] The preparation method of the present invention can achieve catalytic oxidation of OBMF under mild conditions to obtain OBMFCA with high yield; and the catalyst can achieve high catalytic recycling, which can greatly reduce equipment energy consumption, reduce reaction costs, and has green economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 is the XRD pattern of the Au / TiO2 catalyst prepared in Example 1 of the present application;

[0011] Figure 2 It is the OBMFCA prepared in Example 1 of the present application. 1 H NMR spectra. DETAILED DESCRIPTION

[0012] In view of the above problems existing in the prior art, the inventors of the present invention have conducted extensive and in-depth research and provided a method for preparing a 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound.

[0013] The technical solution, its implementation process and principle will be further explained as follows.

[0014] As one aspect of the technical solution of the present invention, a method for preparing a 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound is provided, comprising: forming a first mixed system comprising bis-(5-formylfurfuryl) ether, a supported precious metal catalyst, a first alkaline reagent and water, and performing an oxidation reaction in an oxygen atmosphere to obtain the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound; wherein the supported precious metal catalyst comprises an active metal and a carrier, the active metal comprises at least any one of platinum, gold, iridium, palladium, ruthenium and silver, the carrier comprises at least any one of TiO2, CeO2, HAP and Mn3O4, and the mass fraction of the active metal in the supported precious metal catalyst is 0.1% to 5%.

[0015] Typically, the loading amount of active metal in the supported precious metal catalyst can be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%.

[0016] In some embodiments, the mass ratio of the bis-(5-formylfurfuryl) ether to the supported noble metal catalyst is 1 to 50:1.

[0017] In some preferred embodiments, the mass ratio of the bis-(5-formylfurfuryl) ether to the supported noble metal catalyst is 1 to 10:1.

[0018] In some embodiments, the mass ratio of the bis-(5-formylfurfuryl) ether to the first alkaline agent is 1:5-50.

[0019] In some preferred embodiments, the mass ratio of the bis-(5-formylfurfuryl) ether to the first alkaline agent is 1:10-20.

[0020] In some embodiments, the mass ratio of the bis-(5-formylfurfuryl) ether to water is 1:50-300.

[0021] In some preferred embodiments, the mass ratio of the bis-(5-formylfurfuryl) ether to water is 1:150-250.

[0022] In some embodiments, the oxidation reaction is carried out at a temperature of 10°C to 50°C and for a time of 5 hours to 50 hours.

[0023] In some embodiments, the pressure of the oxygen atmosphere is 0.05 MPa to 1 MPa.

[0024] In some embodiments, the first alkaline agent includes at least one of potassium hydroxide, sodium bicarbonate, sodium hydroxide, ammonia water, etc., but is not limited thereto. A heterogeneous alkaline oxidation system is generally used to catalyze the oxidation of aldehyde groups. This is because the supported metal catalyst has high activity, and the carboxylic acid product OBMFCA generated by the reaction in an alkaline environment will be alkali-soluble to form a carboxylate, thereby accelerating the reaction, and at the same time preventing the product OBMFCA from being adsorbed on the catalyst surface and causing catalyst deactivation.

[0025] In some embodiments, the pH value of the first mixed system is 12-14.

[0026] In some embodiments, the method for preparing the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound uses a reaction apparatus including at least any one of a flask, an intermittent reactor, a fixed bed reactor, etc., but is not limited thereto.

[0027] In some embodiments, the yield of the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound is above 94%.

[0028] In some specific embodiments, the preparation method of the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound specifically comprises:

[0029] A mixture containing bis-(5-formylfurfuryl) ether, a supported noble metal catalyst, a first alkaline reagent and deionized water is added to a reaction device to form a mixed solution; oxygen is then introduced into the reaction device, and an oxidation reaction is carried out for 5 hours to 50 hours under the conditions of an oxygen pressure of 0.05 MPa to 1 MPa and a reaction temperature of 10° C. to 50° C. to prepare the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound.

[0030] Specifically, the synthetic route of OBMFCA in the present invention is as follows:

[0031]

[0032] The specific reaction mechanism is: OBMFCA is obtained by catalytically oxidizing the aldehyde group on the side chain of OBMF to a carboxyl group.

[0033] In some embodiments, the supported noble metal catalyst is synthesized by a deposition precipitation method.

[0034] In some embodiments, the method for preparing the supported noble metal catalyst comprises: calcining a second mixed system comprising a precursor salt of an active metal, a solvent, a support and a second alkaline agent, and then reacting with a reducing agent to obtain a supported noble metal catalyst.

[0035] Furthermore, the preparation method of the supported noble metal catalyst specifically comprises:

[0036] S11, adding a precursor salt solution of an active metal to a carrier solution mixed with a solvent, and then adding a second alkaline agent to mix, so that the active metal component is loaded on the carrier to obtain a solid A;

[0037] S12, calcining the obtained solid A to obtain solid B;

[0038] S13, reacting the obtained solid B with a reducing agent to obtain the supported noble metal catalyst.

[0039] Furthermore, the precursor salt of the active metal includes at least any one of chloride, sulfate, acetate, nitrate, etc. of the active metal, but is not limited thereto.

[0040] Further, the solvent includes at least any one of N,N-dimethylformamide, acetone, water, methanol, ethanol, isopropanol, butanediol, dimethyl sulfoxide, etc., but is not limited thereto.

[0041] Furthermore, the second alkaline reagent includes at least any one of sodium hydroxide, potassium hydroxide, urea, ammonia water, etc., but is not limited thereto.

[0042] Furthermore, the calcination temperature is 50°C to 500°C, and the time is 1h to 24h. Typical temperatures may be 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, etc. Typical calcination times may be 1h, 2h, 3h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h. The calcination temperature will affect the particle size of the metal particles generated, and limiting the heating rate during the calcination process will help control the size of the metal particles. During the calcination process, the temperature rise program should rise at a lower rate (such as 1-5°C / min heating) to ensure that the metal particles are not too large; the calcination time will affect the dispersibility and stability of the active metal on the carrier. The calcination step can convert the metal into the corresponding oxide.

[0043] Furthermore, the calcination temperature is 250° C. to 350° C., and the calcination time is 1 h to 5 h.

[0044] Further, the reducing agent includes at least any one of hydrogen, a mixture of hydrogen and an inert gas, sodium borohydride, formic acid, vitamin C, hydrazine hydrate, etc., but is not limited thereto. The inert gas includes nitrogen or argon, etc.

[0045] Further, the reaction temperature is 50°C to 600°C, and the time is 1h to 12h. Typical reduction times may be 1h, 2h, 4h, 6h, 8h, 10h, 12h. Typical reduction temperatures may be 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C. The reduction step may convert the metal oxide into a metallic state, thereby increasing the catalytic activity.

[0046] Furthermore, the reaction temperature is 200°C to 350°C, and the reaction time is 1h to 5h.

[0047] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0048] If no specific experimental steps or conditions are specified in the examples, the operations or conditions of the conventional experimental steps described in the literature in the art can be carried out. If the manufacturer of the reagents or instruments used is not specified, they can be obtained commercially. Exemplarily, OBMF is purchased from Zhejiang Tangneng Technology Co., Ltd. The commercial selection of the remaining raw materials and instruments not mentioned are all conventional selections and do not involve the core technical means of the present invention.

[0049] The yield of the product OBMFCA in the embodiment is calculated as follows: the conversion rate and selectivity are calculated as follows:

[0050] OBMFCA yield = actual production amount / theoretical production amount × 100%.

[0051] Example 1

[0052] Step 1: Add 10 mg / mL HAuCl4·H2O solution, 10 g urea and 2 g TiO2 carrier into a flask, stir for 30 min, heat the mixture to 80°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0053] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 300°C at a heating rate of 2°C / min in air in a muffle furnace and calcined at this temperature for 2 h.

[0054] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 300°C for 2 hours in a H2 atmosphere to obtain a reduced supported noble metal catalyst Au / TiO2 catalyst. The content of active metal in the Au / TiO2 catalyst is 2wt%.

[0055] Step 4: OBMF substrate and Au / TiO2 catalyst in a mass ratio of 3:1, OBMF and water in a mass ratio of 1:200, and OBMF substrate and NaOH in a mass ratio of 1:15 were added to a 100mL reactor with a polytetrafluoroethylene liner and sealed. Oxygen was repeatedly flushed into the reactor to replace the air in the reactor liner. Then 0.1MPa of oxygen was filled into the reactor, and the temperature was set to 30℃ and reacted for 40h. After the reaction was completed, the reactor was immediately taken out and transferred to ice water for cooling. After cooling, the pressure was released and the reactor liner was taken out. The reaction liquid was treated to obtain a dry target product solid. The dry solid was accurately weighed to calculate the yield, which was recorded as the 0th catalyst application. The filtered catalyst was sent to an oven for drying and then put into the reaction again. The operation steps were the same as above. The catalytic cycle was applied for 10 experiments.

[0056] Figure 1 is the XRD pattern of the Au / TiO2 catalyst prepared in Example 1; Figure 2 is the OBMFCA prepared in Example 1 1 H NMR chart. The yield of OBMFCA is shown in Table 1.

[0057] Example 2

[0058] Step 1: Add 10 mg / mL HAuCl4·H2O solution, 10 g urea and 2 g CeO2 carrier into a flask, stir for 30 min, heat the mixture to 100°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0059] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 400°C at a heating rate of 5°C / min in air in a muffle furnace and calcined at this temperature for 2h.

[0060] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 350°C for 2 hours under a H2 atmosphere to obtain a reduced supported metal catalyst Au / CeO2 catalyst. The content of active metal in the Au / CeO2 catalyst is 2wt%.

[0061] Step 4: The supported metal catalyst Au / CeO2 prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1, wherein the mass ratio of OBMF substrate to Au / CeO2 catalyst is 3:1, the mass ratio of OBMF to water is 1:200, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0062] Example 3

[0063] Step 1: Add 10 mg / mL HAuCl4·H2O solution, 10 g urea and 2 g TiO2 carrier into a flask, stir for 30 min, heat the mixture to 100°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0064] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 500°C at a heating rate of 5°C / min in air in a muffle furnace and calcined at this temperature for 2 h.

[0065] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 400°C for 2 hours in a H2 atmosphere to obtain a reduced supported metal catalyst Au / TiO2 catalyst. The content of active metal in the Au / TiO2 catalyst is 2wt%.

[0066] Step 4: The supported metal catalyst Au / TiO2 prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1, wherein the mass ratio of OBMF substrate to Au / TiO2 catalyst is 3:1, the mass ratio of OBMF to water is 1:200, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0067] Example 4

[0068] Step 1: Add 10 mg / mL H2PtCl6 aqueous solution, 10 g urea and 2 g TiO2 carrier into a flask, stir for 30 min, heat the mixture to 100°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0069] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 300°C at a heating rate of 5°C / min in air in a muffle furnace and calcined at this temperature for 2h.

[0070] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 300°C for 2 hours under a H2 atmosphere to obtain a reduced supported metal catalyst Pt / TiO2 catalyst. The content of active metal in the Pt / TiO2 catalyst is 2wt%.

[0071] Step 4: The supported metal catalyst Pt / TiO2 prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1, wherein the mass ratio of OBMF substrate to Pt / TiO2 catalyst is 3:1, the mass ratio of OBMF to water is 1:200, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0072] Example 5

[0073] Step 1: Add 10 mg / mL RuCl3·H2O aqueous solution, 10 g urea and 2 g TiO2 carrier into a flask, stir for 30 min, heat the mixture to 100°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0074] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 300°C at a heating rate of 5°C / min in air in a muffle furnace and calcined at this temperature for 2h.

[0075] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 300°C for 2 hours under a H2 atmosphere to obtain a reduced supported metal catalyst Ru / TiO2 catalyst. The content of active metal in the Ru / TiO2 catalyst is 2wt%.

[0076] Step 4: The supported metal catalyst Ru / TiO2 prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1, wherein the mass ratio of OBMF substrate to Ru / TiO2 catalyst is 3:1, the mass ratio of OBMF to water is 1:200, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0077] Example 6

[0078] Step 1: Add 10 mg / mL PdCl2 aqueous solution, 10 g urea and 2 g HAP carrier into a flask, stir for 30 min, heat the mixture to 100°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0079] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 300°C at a heating rate of 5°C / min in air in a muffle furnace and calcined at this temperature for 2h.

[0080] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 300°C for 2 hours under H2 atmosphere to obtain a reduced supported metal catalyst Pd / HAP catalyst. The content of active metal in the Pd / HAP catalyst is 2 wt%.

[0081] Step 4: The supported metal catalyst Pd / HAP prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1, wherein the mass ratio of OBMF substrate to Pd / HAP catalyst is 3:1, the mass ratio of OBMF to water is 1:200, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0082] Example 7

[0083] Step 1: Add 10 mg / mL HAuCl4·H2O aqueous solution, 10 g urea and 2 g HAP carrier into a flask, stir for 30 min, heat the mixture to 100°C and keep stirring at this temperature for 10 h. Then, filter the mixture with suction and dry it at 100°C overnight.

[0084] Step 2: The catalyst solid obtained after drying was ground into powder in an agate mortar and placed in a crucible. It was then heated to 300°C at a heating rate of 5°C / min in air in a muffle furnace and calcined at this temperature for 2h.

[0085] Step 3: After the calcined catalyst is ground again, it is placed in a tube furnace and reduced at 300°C for 2 hours under H2 atmosphere to obtain a reduced supported metal catalyst Au / HAP catalyst. The content of active metal in the Au / HAP catalyst is 2wt%.

[0086] Step 4: The supported metal catalyst Au / HAP prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1, wherein the mass ratio of OBMF substrate to Au / HAP catalyst is 3:1, the mass ratio of OBMF to water is 1:200, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0087] Example 8

[0088] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that:

[0089] In step 4, the mass ratio of OBMF substrate to Au / TiO2 catalyst is 3:1, the mass ratio of OBMF to water is 1:50, and the mass ratio of OBMF substrate to KOH is 1:5;

[0090] The oxidation reaction temperature is 50°C, the reaction time is 50h, and the oxygen pressure is 1Mpa.

[0091] Example 9

[0092] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that:

[0093] In step 4, the mass ratio of OBMF substrate to Au / TiO2 catalyst is 3:1, the mass ratio of OBMF to water is 1:300, and the mass ratio of OBMF substrate to NaHCO3 is 1:50;

[0094] The oxidation reaction temperature is 10°C, the reaction time is 5h, and the oxygen pressure is 0.05Mpa.

[0095] Example 10

[0096] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that: 3 wt% of the Au / TiO2 catalyst is loaded;

[0097] In step 4, the mass ratio of OBMF substrate to Au / TiO2 catalyst is 25:1, the mass ratio of OBMF to water is 1:50, and the mass ratio of OBMF substrate to NaOH is 1:25.

[0098] Embodiment 11

[0099] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that: 5 wt% loading of Au / TiO2 catalyst;

[0100] In step 4, the mass ratio of OBMF substrate to Au / TiO2 catalyst is 50:1, the mass ratio of OBMF to water is 1:300, and the mass ratio of OBMF substrate to NaOH is 1:15.

[0101] Comparative Example 1

[0102] Step 1: Prepare Au / TiO2 catalyst by impregnation method. Mix chloroauric acid aqueous solution with 2 g of TiO2 carrier, impregnate for 12 hours, and then dry in an oven for 12 hours.

[0103] Step 2: The obtained solid was calcined in a muffle furnace in air at 400° C. for 12 h to obtain a calcined solid A.

[0104] Step 3: Solid A was reduced at 400°C for 6 h in a tube furnace under a hydrogen atmosphere to obtain an Au / TiO2 catalyst prepared by the impregnation method.

[0105] Step 4: The supported metal catalyst Au / TiO2 prepared by the impregnation method is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1. The input ratio of Au / TiO2 catalyst, water, NaOH and OBMF substrate is consistent with that in Example 1.

[0106] Comparative Example 2

[0107] Step 1: Prepare Pt / TiO2 catalyst by impregnation method. Mix chloroauric acid aqueous solution with 2 g of TiO2 carrier, impregnate for 12 hours, and then dry in an oven for 12 hours.

[0108] Step 2: The obtained solid was calcined in a muffle furnace at 500° C. in air for 12 h to obtain a calcined solid A.

[0109] Step 3: Solid A was reduced in a tubular furnace at 300°C for 6 h under a hydrogen atmosphere to obtain a Pt / TiO2 catalyst prepared by an impregnation method.

[0110] Step 4: The supported metal catalyst Pt / TiO2 prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1. The input ratio of Pt / TiO2 catalyst, water, NaOH and OBMF substrate is consistent with that in Example 1.

[0111] Comparative Example 3

[0112] Step 1: Prepare Au / HY catalyst using the method shown in Example 1 of invention patent CN103626726A.

[0113] Step 2: The supported metal catalyst Au / HY prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1. The input ratio of Au / HY catalyst, water, NaOH and OBMF substrate is consistent with that in Example 1.

[0114] Comparative Example 4

[0115] Step 1: Prepare 10% Fe-CeO2-550°C catalyst by the method shown in the embodiment of invention patent CN109293608A.

[0116] Step 2: The supported metal catalyst 10% Fe-CeO2-550°C prepared above is applied to the catalytic oxidation of OBMF to prepare OBMFCA reaction, and the operation steps are the same as those in Example 1. The input ratio of 10% Fe-CeO2-550°C catalyst, water, NaOH and OBMF substrate is consistent with that in Example 1.

[0117] Comparative Example 5

[0118] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that:

[0119] In step 4, the OBMF substrate was changed to 5-hydroxyfurfural (HMF).

[0120] Comparative Example 6

[0121] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that:

[0122] In step 4, the mass ratio of OBMF substrate to Au / TiO2 catalyst is 1:1, the mass ratio of OBMF to water is 1:50, and the mass ratio of OBMF substrate to NaOH is 1:5;

[0123] The reaction conditions are a temperature of 5°C, an oxygen pressure of 0.02MPa, and an oxidation reaction time of 0.5h.

[0124] Comparative Example 7

[0125] Step 1, step 2, step 3 and step 4 are the same as those in Example 1, except that:

[0126] In step 4, the mass ratio of OBMF substrate to Au / TiO2 catalyst is 1:50, the mass ratio of OBMF to water is 1:300, and the mass ratio of OBMF substrate to NaOH is 1:50;

[0127] The reaction conditions are temperature of 100°C, oxygen pressure of 2MPa, and oxidation reaction time of 100h.

[0128] Table 1 OBMFCA yields of Examples 1-11 and Comparative Examples 1-7

[0129]

[0130] In Comparative Example 4, since the active metal of the catalyst is Fe element, which is a base metal, OBMF cannot be catalyzed to oxidize to obtain OBMFCA under the same reaction conditions as in Example 1 of the present invention. In Comparative Example 5, when the OBMF substrate is switched to HMF, HMF cannot be catalyzed to oxidize directly to OBMFCA under the same reaction conditions as in Example 1 of the present invention, and HMF will be oxidized to generate FDCA.

[0131] In summary, in an alkaline environment, the present invention uses a supported noble metal catalyst to catalytically oxidize bis-(5-formylfurfuryl) ether to obtain the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound. The preparation method can achieve catalytic oxidation of OBMF under mild conditions to obtain high-yield OBMFCA; and the catalyst can achieve high catalytic recycling, and the recycling is more than 10 times without a significant decrease in yield, which can greatly reduce equipment energy consumption, reduce reaction costs, and has green economy.

[0132] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all aspects and are not intended to limit the present invention, the scope of the present invention is defined only by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0133] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0134] Although the present invention has been described with reference to illustrative embodiments, it will be appreciated by those skilled in the art that various other changes, omissions and / or additions may be made without departing from the spirit and scope of the present invention and that the elements of the embodiments may be replaced by substantial equivalents. In addition, many modifications may be made without departing from the scope of the present invention to adapt specific circumstances or materials to the teachings of the present invention. Therefore, it is not intended herein to limit the present invention to the disclosed specific embodiments for performing the present invention, but it is intended that the present invention will include all embodiments within the scope of the appended claims. In addition, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but rather uses the terms first, second, etc. to distinguish one element from another.

Claims

1. A method for preparing a 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound, characterized in that: include: Forming a first mixed system comprising bis-(5-formylfurfuryl) ether, a supported noble metal catalyst, a first alkaline reagent and water, and performing an oxidation reaction in an oxygen atmosphere to obtain the 5,5′-[oxybis(methylene)]bis[2-furancarboxylic acid] compound; The supported precious metal catalyst comprises an active metal and a carrier, wherein the active metal comprises at least any one of platinum, gold, iridium, palladium, ruthenium and silver, and the carrier comprises at least any one of TiO2, CeO2, HAP and Mn3O4, and the mass fraction of the active metal in the supported precious metal catalyst is 0.1% to 5%.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the bis-(5-formylfurfuryl) ether to the supported noble metal catalyst is 1 to 50:1, preferably 1 to 10:1; and / or, the mass ratio of the bis-(5-formylfurfuryl) ether to the first alkaline agent is 1:5 to 50, preferably 1:10 to 20; And / or, the mass ratio of the bis-(5-formylfurfuryl) ether to water is 1:50-300, preferably 1:150-250.

3. The preparation method according to claim 1, characterized in that: The oxidation reaction temperature is 10°C to 50°C and the time is 5h to 50h; And / or, the pressure of the oxygen atmosphere is 0.05 MPa to 1 MPa.

4. The preparation method according to claim 1, characterized in that: The first alkaline reagent includes at least any one of potassium hydroxide, sodium bicarbonate, sodium hydroxide, and ammonia water.

5. The preparation method according to claim 1, characterized in that: The pH value of the first mixed system is 12-14.

6. The preparation method according to claim 1, characterized in that: The reaction device used in the preparation method includes at least any one of a flask, an intermittent tank reactor and a fixed bed reactor.

7. The preparation method according to claim 1, characterized in that: The yield of the 5,5'-[oxybis(methylene)]bis[2-furancarboxylic acid] compound is above 94%.

8. The preparation method according to claim 1, characterized in that: The supported noble metal catalyst is synthesized by a deposition precipitation method.

9. The preparation method according to claim 1 or 8, characterized in that: The preparation method of the supported noble metal catalyst comprises: calcining a second mixed system including a precursor salt of an active metal, a solvent, a carrier and a second alkaline reagent, and then reacting with a reducing agent to obtain the supported noble metal catalyst.

10. The preparation method according to claim 9, characterized in that: The precursor salt of the active metal includes at least any one of chloride, sulfate, acetate and nitrate of the active metal; And / or, the solvent includes at least any one of N,N-dimethylformamide, acetone, water, methanol, ethanol, isopropanol, butanediol, and dimethyl sulfoxide; And / or, the second alkaline reagent includes at least any one of sodium hydroxide, potassium hydroxide, urea, and ammonia water; And / or, the calcination temperature is 50°C to 500°C, and the calcination time is 1h to 24h; Preferably, the calcination temperature is 250°C to 350°C, and the calcination time is 1h to 5h; And / or, the reducing agent includes at least any one of hydrogen, a mixed gas of hydrogen and an inert gas, sodium borohydride, formic acid, vitamin C, and hydrazine hydrate; the inert gas includes nitrogen or argon; And / or, the reaction temperature is 50°C to 600°C, and the reaction time is 1h to 12h; Preferably, the reaction temperature is 200°C to 350°C, and the reaction time is 1h to 5h.

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