A method for preparing formic acid by catalytic oxygen oxidation of biomass carbohydrates

Abstract

The present invention relates to a method for preparing formic acid by catalytic oxygen oxidation of carbohydrates in a separate manner of catalyst reduction and reoxidation. 40 Using H8PV5Mo7O as a catalyst, the carbohydrates are first selectively oxidized in water to produce formic acid with ultra-high yield, and the catalyst is reduced at the same time. Then, the reduced catalyst is regenerated with oxygen as an oxidant for the next round of carbohydrate oxidation. Compared with the traditional method of preparing formic acid, this method uses biomass carbohydrates as raw materials, avoids environmental pollution, and is sustainable; the reaction conditions are mild and the formic acid yield is high. 40 As a catalyst, it not only has high oxidation activity and good selectivity, but also has high reoxidation activity. Compared with the general method of preparing formic acid by catalytic oxygen oxidation of carbohydrates, this method can significantly improve the selectivity of formic acid and improve the carbon atom utilization rate of carbohydrates.

Description

Technical Field

[0001] The present invention relates to a method for preparing formic acid by catalytic oxidation of biomass, and in particular to a method for preparing formic acid by catalytic oxygen oxidation of biomass carbohydrates in a manner of separate reduction and reoxidation of a catalyst. Technical Background

[0002] With the rapid development of the global economy and the continuous increase in population, problems such as resource shortage, greenhouse effect and environmental pollution have attracted increasing attention. Renewable resources replacing fossil resources has become a hot research topic for sustainable development. Although renewable energy such as hydropower, wind power and solar energy can alleviate the pressure of fossil fuels, they cannot solve the problem of chemical production. As the only renewable carbon source existing in large quantities on the earth, biomass provides the possibility for the sustainable supply of chemical products and transportation fuels.

[0003] Formic acid is an important chemical raw material. Due to its unique properties, it is widely used in the textile, leather, medicine, agriculture and chemical industries. In biomass conversion, formic acid can replace inorganic acid as an acidic catalyst to avoid equipment corrosion and the impact on subsequent reactions; formic acid can also be used as a hydrogen donor to provide in-situ hydrogen in the process of biomass hydrogenolysis. In recent years, formic acid has also played an increasingly important role in the energy field and has broad application prospects in fuel cells and hydrogen production. Formic acid fuel cells have the advantages of high energy density, low cross-flux, environmental protection, and non-flammability. As a hydrogen production raw material, formic acid has a high hydrogen capacity (53.4g / L) and good transportation and storage safety. At present, the industrial production methods of formic acid mainly include sodium formate method, methyl formate hydrolysis method, formamide method, etc. However, the raw materials of these methods are all derived from fossil fuels. Although these traditional methods can produce a large amount of formic acid, the production process causes serious pollution and the production raw materials are non-renewable, which restricts the efficient and sustainable production of formic acid. Based on the requirements of sustainable development and green chemical industry, it is urgent to develop a new formic acid production process with high efficiency, low pollution and good sustainability.

[0004] Biomass-based carbohydrates are widely distributed and renewable carbon resources. Lignocellulose can be obtained from plant residues and wastes in agriculture, forestry and industry. It is abundant and cheap. Lignocellulose contains 50-90wt% carbohydrates (including cellulose and hemicellulose), which have high oxygen content and are suitable for conversion into oxygen-containing chemicals, such as formic acid.

[0005] At present, there are some reports on the use of carbohydrates to prepare formic acid. For example, Chinese patent (application number 201080019836.6) discloses a method for producing formic acid, which involves hydrolyzing carbohydrate-containing materials in the presence of inorganic acid to produce formic acid, but the yield of formic acid (carbon yield, the same below) is very low and requires the consumption of a large amount of inorganic acid. Chinese patent (application number 201110099183.3) discloses a method for preparing acetone and calcium formate from biomass waste, which involves converting biomass into formic acid and acetic acid under severe reaction conditions, but the product formic acid yield is low and the reaction energy consumption is high. Chinese patent (application number 201180054759.2) discloses a method for catalytic production of formic acid, which catalytically oxidizes carbohydrates at low temperatures to prepare formic acid. The method obtains formic acid under mild conditions, but there is a problem that the yield of formic acid is limited due to the production of carbon dioxide by peroxidation.

[0006] There are also reports on the catalytic oxidation of carbohydrates to produce formic acid in journal articles. Jin et al. (Jin F, Enomoto H. Rapid and highly selective conversion of biomass into value-added products in hydrothermal conditions: chemistry of acid / base-catalysed and oxidation reactions. Energy & Environmental Science, 2011, 4(2): 382-397) used inorganic bases such as NaOH as catalysts and H 2 O 2 As an oxidant, cellulose was oxidized at a high temperature of 250°C to produce formic acid (sodium salt) with a yield of up to 75%. However, this method has a high operating temperature and consumes a large amount of alkali in the reaction, which has certain limitations in industrial applications. Other researchers have proposed catalytic oxidation of carbohydrates in an acidic aqueous solution to produce formic acid. wait( R,Taccardi N, A, Wasserscheid P.Selective catalytic conversion of biobased carbohydrates to formic acid using molecular oxygen. Green Chemistry, 2011, 13(10):2759-2763) with heteropolyacid H 5 PV 2 Mo 10 O 40As a catalyst, glucose was catalyzed at 80℃ and 3MPa O 2 The conversion yielded 49% formic acid. Albert et al. (Albert J, Lüders D, A, Guldi DM, Wasserscheid P. Spectroscopic and electrochemical characterization of heteropoly acids for their optimized application in selective biomass oxidation to formic acid. Green Chemistry, 2014, 16: 226-237) found that with the increase of vanadium substitution degree, heteropoly acids showed better catalytic performance, among which H 8 PV 5 Mo 7 O 40 The best performance was achieved, which was able to convert glucose into formic acid with a yield of 57.3%. Li et al. (Li J, Ding DJ, Deng L, Guo QX, Fu Y. Catalytic air oxidation of biomass-derived carbohydrates to formic acid. ChemSusChem, 2012, 5(7): 1313-1318) used H 5 PV 2 Mo 10 O 40 Catalytic oxidation of cellulose to formic acid in H 5 PV 2 Mo 10 O 40 +H 2 SO 4 aqueous solution with molecular oxygen. Green Chemistry, 2016, 18(17): 4725-4732) reported in H 5 PV 2 Mo 10 O 40 -H 2 SO 4The system catalyzes oxygen oxidation of cellulose to produce formic acid, and the formic acid yield reaches 61%. The method of oxidizing carbohydrates to produce formic acid in an acidic catalytic system can obtain formic acid under relatively mild conditions. However, this method still has the problem of low formic acid selectivity. The formic acid yield reported so far does not exceed 70%, and more than 30% of the organic carbon in the raw material is converted into by-product CO 2 This not only reduces the utilization rate of carbon atoms in the raw materials, but also produces a large amount of CO 2 It is not conducive to the realization of the dual carbon goals as soon as possible. 2 To improve the yield of formic acid, some researchers changed the solvent composition (Lu, T.; Hou, YC; Wu, WZ; Niu, MG; Ren, SH; Lin, ZQ; Ramani, VK) to improve the yield of formic acid. 5 PV 2 Mo 10 O 40 .Fuel 2018,216,572-578), and some researchers added dimethyl sulfoxide to the catalytic oxidation system (Guo, YJ; Li, SJ; Sun, YL; Wang, L.; Zhang, WM; Zhang, P.; Lan, Y.; Li, Y. Practical DMSO-promoted selective hydrolysis–oxidation of lignocellulosic biomass to formic acid attributed to hydrogen bonds. Green Chem. 2021, 23, 7041-7052), but these methods will consume additional organic solvents or additives, and increase the difficulty of subsequent product purification. Therefore, it is necessary to find a new method for carbohydrate oxidation that can suppress the byproduct CO without the introduction of organic additives. 2 The production of formic acid can be improved. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the present invention provides a method for preparing formic acid by cyclic catalytic oxidation of carbohydrates by Keggin-type vanadium-containing heteropoly acid, wherein the reduction and reoxidation of the heteropoly acid catalyst are separated to achieve high-selectivity catalytic oxidation of carbohydrates to prepare formic acid. The method uses biomass carbohydrates as raw materials, water as solvent, and Keggin-type vanadium-containing heteropoly acid H 3+n PV n Mo12 -nO 40 (HPA-n, n = 2-6) is a catalyst and oxygen is an oxidant. The oxidized heteropoly acid (HPA-n) is first used to highly selectively oxidize the carbohydrate to formic acid, while the heteropoly acid is reduced. Then, the reduced heteropoly acid (HPA-n) is oxidized to form formic acid with oxygen. red ) is then oxidized to HPA-n for the next round of carbohydrate oxidation (such as Figure 1 The catalytic oxygen oxidation of carbohydrates by separating the reduction and reoxidation of the catalyst is an efficient and renewable method for producing formic acid. It can significantly increase the yield of formic acid without adding organic additives, improve the atomic utilization of biomass, and provide a new technology for the industrial application of highly selective oxidation of carbohydrates to prepare formic acid.

[0008] The present invention provides a method for preparing formic acid by cyclic catalytic oxidation of Keggin-type vanadium-containing heteropolyacid, which comprises three steps: (a) oxidizing carbohydrates into formic acid using HPA-n in a water solvent; (b) extracting the formic acid product using an extractant, and the raffinate phase is a phase rich in HPA-n. red (c) providing oxygen or air atmosphere to HPA-n red Reoxidized to HPA-n for the next round of carbohydrate oxidation.

[0009] In step (a) of the above preparation method, the carbohydrate is selected from one of glucose, arabinose, erythrose, glyceraldehyde, glycoaldehyde, cellulose and xylan.

[0010] In step (a) of the above preparation method, the added amount of the carbohydrate is 0.18 wt % to 3.6 wt % based on the mass of the solvent.

[0011] In step (a) of the above preparation method, the HPA-n is selected from one of HPA-2, HPA-3, HPA-4, HPA-5 and HPA-6, preferably HPA-5.

[0012] In step (a) of the above preparation method, based on the number of C atoms in the carbohydrate, the molar ratio of V atoms in the HPA-n to C atoms in the carbohydrate is 1 to 4, preferably 3 to 4.

[0013] In step (a) of the above preparation method, the temperature of the carbohydrate oxidation reaction is 120°C to 180°C.

[0014] In step (a) of the above preparation method, the carbohydrate oxidation reaction time is 1 min to 60 min, preferably 10 min to 60 min.

[0015] In step (b) of the above preparation method, the extractant is ether or ethyl acetate, the volume ratio of the extractant to the reaction solution is 10, and the extraction is performed in 3 to 7 times.

[0016] In step (c) of the above preparation method, the oxidant is pure oxygen or air, and the initial partial pressure of oxygen is 0.5 MPa to 2.5 MPa, preferably 1.5 MPa to 2.5 MPa.

[0017] In step (c) of the above preparation method, HPA-n red The reaction temperature of the reoxidation is 30°C to 70°C, preferably 50°C to 70°C.

[0018] In step (c) of the above preparation method, HPA-n red The reoxidation reaction time was 10 min.

[0019] The principle of the method for preparing formic acid by highly selectively oxidizing carbohydrates of the present invention is that insoluble carbohydrates (such as cellulose) are first hydrolyzed into soluble carbohydrates under the acidic action of the catalyst, and the soluble carbohydrates undergo highly selective CC bond cleavage to generate formic acid under the oxidation action of the oxidized catalyst HPA-n. When HPA-n oxidizes carbohydrates, oxygen atoms are transferred from the catalyst to the oxidized products of the carbohydrates, accompanied by electron transfer, and the pentavalent vanadium in the catalyst is reduced to tetravalent vanadium. The reduced catalyst HPA-n red In step (c), the HPA-n is reoxidized by oxygen, and the oxygen atom is transferred from the oxygen to the catalyst, accompanied by electron transfer, and the tetravalent vanadium in the catalyst is oxidized to pentavalent vanadium. The reoxidation process of the catalyst will produce hydroxyl radicals, which have a high redox potential and low selectivity for formic acid during oxidation. The reaction of carbohydrates with hydroxyl radicals will cause peroxidation to produce CO 2 This is because carbohydrates produce a large amount of CO when they are catalyzed by oxygen oxidation in HPA-n aqueous solution. 2 Causes of by-products: If the oxidation of carbohydrates (i.e., the reduction of the catalyst) and the reoxidation of the catalyst are carried out separately, the contact of hydroxyl radicals with carbohydrates can be avoided, thereby greatly reducing overoxidation and improving the selectivity of formic acid.

[0020] Compared with the preparation of formic acid by catalytic oxygen oxidation of carbohydrates in the literature, the method of the present invention has the following advantages: (1) without adding any organic additives, the selectivity of formic acid production is greatly improved, and the by-product CO is suppressed. 2 The production of polyols has a high atomic utilization rate; (2) no organic additives are required, the solvent is water, and it is highly safe; (3) the product is a formic acid solution, and no further hydrolysis or acidification is required. (4) The high concentration of heteropolyacids can provide strong acidity for the hydrolysis of insoluble carbohydrates, without the need for additional acid addition.

[0021] Compared with the industrial method for preparing formic acid, the method of the present invention has the following advantages: (1) The method uses cheap and abundant biomass-based carbohydrates as raw materials, which not only reduces costs but also avoids environmental pollution problems caused by the use of fossil energy. The method is based on renewable biomass resources, making the method sustainable; (2) The method of the present invention has mild reaction conditions, a simple process, and a high formic acid yield. It can be foreseen that the method has high application potential; (3) The present invention selects water-soluble vanadium-containing heteropoly acid HPA-n as a catalyst, which has high oxidation activity and selectivity in the oxidized state; and has high reoxidation activity in the reduced state, and can be regenerated under mild conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a method for preparing formic acid by catalytic oxygen oxidation of carbohydrates by separate reduction and reoxidation of the catalyst. DETAILED DESCRIPTION

[0023] The present invention is further illustrated by the following examples, but the protection scope of the present invention is not limited to the following examples.

[0024] Example 1

[0025] This example includes three steps, carbohydrate oxidation, product extraction and catalyst reoxidation.

[0026] (a) Carbohydrate oxidation: Glucose was used as the raw material and HPA-5 was used as the catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50 mL high temperature and high pressure reactor with magnetic stirring. 0.018 g of glucose, 0.42 mmol of HPA-5 and 10 mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18 wt %, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160 ° C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor cooled to room temperature, the gaseous products were discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous products and liquid products were taken for analysis.

[0027] (b) Product extraction: The reaction solution in step (a) was transferred to a separatory funnel, and the formic acid product in the reaction solution was extracted with ether as an extractant. The volume ratio of ether to the reaction solution was 10, and the extraction was performed 5 times. The raffinate phase was then purged with nitrogen for 10 minutes to remove the introduced ether, and the reduced catalyst HPA-5 was obtained.red Aqueous solution, transfer to a graduated cylinder to determine the volume, and take a certain volume of sample for analysis.

[0028] (c) Catalyst reoxidation: HPA-5 from step (b) red The aqueous solution was transferred to a 50mL high-temperature and high-pressure reactor, which was sealed. The air in the reactor was replaced with oxygen, and then filled with 2.0MPa of oxygen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 60°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor cooled to room temperature, the gas in the reactor was evacuated, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of sample was taken for analysis. The rest of the reaction liquid was used for the next round of carbohydrate oxidation.

[0029] Analysis: Gas samples were analyzed by gas chromatography to determine CO 2 The amount of product generated. The gas chromatograph used is Agilent7890A, the chromatographic column is 50 / 80Porapak Q column, the detector is TCD, and the carrier gas is helium. The liquid sample was analyzed by high performance liquid chromatography for the composition and content of each product. The high performance liquid chromatograph used is Waters 2695, the detector is a differential detector, the chromatographic column is Shodex SH 1011 carbohydrate column, the column temperature is 55°C, the mobile phase is a sulfuric acid aqueous solution with a mass fraction of 0.1wt%, and the flow rate of the mobile phase is 0.5mL / min. In addition, the liquid sample after reoxidation of the catalyst was subjected to UV-visible spectroscopy to analyze the reoxidation degree of the reduced catalyst. The UV-visible spectrometer used is TU-1901, the wavelength range is 400nm~900nm, and the specification of the cuvette is 10mm×5mm. According to the absorbance at 750nm (HPA-5 red The characteristic response intensity of the reoxidation factor was used to judge the degree of reoxidation.

[0030] The results show:

[0031] (a) Carbohydrate oxidation: The conversion rate of glucose was 100%, and the only liquid product was formic acid. The carbon yield of formic acid was 95.4% based on the organic C content of the initial glucose. The gaseous product was CO 2 , with a yield of 2.7%.

[0032] (b) Product extraction: The extraction efficiency of formic acid by ether was calculated based on the content of formic acid in the reaction solution before extraction and was 98.3%.

[0033] (c) Reoxidation of the catalyst: After reoxidation, the absorbance of the catalyst solution at 750 nm in the UV-visible spectrum was 0.0, indicating that HPA-5 red All of it has been reoxidized to HPA-5.

[0034] Example 2

[0035] This example is a cyclic experiment of the oxidation method. In the first cycle, the reaction liquid after the catalyst is reoxidized in step (c) of Example 1 is used as the catalyst solution, and glucose is used as the raw material to oxidize carbohydrates to prepare formic acid. The method of the carbohydrate oxidation experiment is basically the same as step (a) of Example 1, and no additional deionized water is required; the conditions keep the molar ratio of V atoms in HPA-5 to C atoms in glucose unchanged at 3.5. The subsequent product extraction and catalyst reoxidation steps are the same as steps (b) and (c) of Example 1. The second to fourth cycles are carried out according to the method of the first cycle, and each cycle uses the reaction liquid after the catalyst is reoxidized in the previous cycle as the catalyst solution.

[0036] The analysis conditions and methods are the same as in Example 1.

[0037] The results showed that the conversion rate of glucose in each cycle was 100%, and the only liquid product was formic acid. The carbon yields of formic acid obtained from the first to fourth cycles were 93.9%, 94.4%, 92.3% and 93.6%, respectively, based on the organic C content of the initial glucose. The gaseous product was CO 2 , CO from the first to fourth cycles 2 The yields were 2.8%, 2.7%, 3.5% and 2.9% respectively.

[0038] Example 3

[0039] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.24mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 2), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 10 minutes, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0040] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid product was 91.8% based on the organic carbon content of the initial glucose, including 85.2% formic acid, 0.9% acetic acid, 4.0% glycolic acid, 1.3% glyceric acid, 0.1% 5-hydroxymethylfurfural, and 0.3% fructose; the gaseous product was CO 2 , with a yield of 3.0%.

[0041] Example 4

[0042] This example is a comparative experiment, comparing the formic acid yield obtained by general catalytic oxygen oxidation with CO 2 Yield.

[0043] Glucose was used as raw material, HPA-5 was used as catalyst, and oxygen was used as oxidant to catalyze the oxidation of carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g glucose, 0.24mmol HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%), the reactor was sealed, the air in the reactor was replaced with oxygen, and then 2.0MPa of oxygen was filled. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods were the same as those in Example 1.

[0044] The results showed that the conversion rate of glucose was 100%, the liquid product was only formic acid, and the carbon yield of formic acid was 57.3% based on the organic C content of the initial glucose; the gaseous product was CO 2 , with a yield of 39.4%. Compared with the oxidation method of Example 3 in which the carbohydrate oxidation and catalyst reoxidation are separated, the CO 2 The yield is significantly higher, with lower selectivity for formic acid.

[0045] Example 5

[0046] In this embodiment, glucose is used as a raw material and HPA-2 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.6mmol of HPA-2 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-2 to C atoms in glucose was 2), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 10 minutes, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0047] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 89.2% based on the organic carbon content of the initial glucose, including 78.2% formic acid, 2.6% acetic acid, 4.5% glycolic acid, 1.3% glyceric acid, 0.5% 5-hydroxymethylfurfural, 0.8% fructose, and 1.3% gluconic acid; the gas phase product was CO 2 , with a yield of 3.0%.

[0048] Example 6

[0049] In this embodiment, glucose is used as a raw material and HPA-3 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.4mmol of HPA-3 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-3 to C atoms in glucose was 2), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0050] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 87.1% based on the organic carbon content of the initial glucose, including 75.3% formic acid, 2.4% acetic acid, 5.8% glycolic acid, 1.6% glyceric acid, 0.2% 5-hydroxymethylfurfural, 0.8% fructose, and 1.0% gluconic acid; the gas phase product was CO 2 , with a yield of 3.9%.

[0051] Example 7

[0052] In this embodiment, glucose is used as a raw material and HPA-4 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.3mmol of HPA-4 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-4 to C atoms in glucose was 2), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 10 minutes, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0053] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 89.3% based on the organic C content of the initial glucose, including 77.6% formic acid, 2.5% acetic acid, 5.6% glycolic acid, 0.7% glyceric acid, 0.2% 5-hydroxymethylfurfural, 1.2% fructose, and 1.5% gluconic acid; the gas phase product was CO 2 , with a yield of 2.8%.

[0054] Example 8

[0055] In this embodiment, glucose is used as a raw material and HPA-6 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.2mmol of HPA-6 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-6 to C atoms in glucose was 2), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0056] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 93.6% based on the organic carbon content of the initial glucose, including 83.2% formic acid, 0.7% acetic acid, 6.9% glycolic acid, 1.9% glyceric acid, and 0.9% fructose; the gas phase product was CO 2 , with a yield of 2.8%.

[0057] Example 9

[0058] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.12mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 1), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0059] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 88.6% based on the organic carbon content of the initial glucose, including 52.7% formic acid, 4.9% acetic acid, 10.2% glycolic acid, 9.0% glyceric acid, 0.6% 5-hydroxymethylfurfural, and 11.2% fructose; the gas phase product was CO 2 , with a yield of 2.3%.

[0060] Example 10

[0061] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.18mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 1.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 10 minutes, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0062] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 89.3% based on the organic carbon content of the initial glucose, including 75.4% formic acid, 2.0% acetic acid, 6.2% glycolic acid, 2.9% glyceric acid, 0.6% 5-hydroxymethylfurfural, and 2.2% fructose; the gas phase product was CO 2 , with a yield of 2.4%.

[0063] Embodiment 11

[0064] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.3mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 2.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 10 minutes, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0065] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 93.9% calculated based on the organic C content of the initial glucose, including 93.0% formic acid and 0.9% glycolic acid; the gas phase product was CO 2 , with a yield of 3.0%.

[0066] Example 12

[0067] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.36mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0068] The results showed that the conversion rate of glucose was 100%, the liquid product was only formic acid, and the carbon yield of formic acid calculated based on the organic C content of the initial glucose was 94.4%; the gaseous product was CO 2 , with a yield of 2.9%.

[0069] Embodiment 13

[0070] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.48mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 4), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0071] The results showed that the conversion rate of glucose was 100%, the liquid product was only formic acid, and the carbon yield of formic acid calculated based on the organic C content of the initial glucose was 93.6%; the gaseous product was CO 2 , with a yield of 2.8%.

[0072] Embodiment 14

[0073] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.42mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 1min, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0074] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 96.7% calculated based on the organic C content of the initial glucose, including 95.0% formic acid and 1.7% glycolic acid; the gas phase product was CO 2 , with a yield of 2.4%.

[0075] Embodiment 15

[0076] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.09g of glucose, 2.1mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.9wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 1min, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0077] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 94.9% calculated based on the organic C content of the initial glucose, including 92.8% formic acid and 2.1% glycolic acid; the gas phase product was CO 2 , with a yield of 2.8%.

[0078] Example 16

[0079] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.18g of glucose, 4.2mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 1.8wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 1min, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0080] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 93.6% calculated based on the organic C content of the initial glucose, including 91.3% formic acid and 2.3% glycolic acid; the gas phase product was CO 2 , with a yield of 4.8%.

[0081] Embodiment 17

[0082] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.36g of glucose, 8.4mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 3.6wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 1min, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0083] The results showed that the conversion rate of glucose was 100%, and the organic carbon yield of the liquid phase product was 92.2% calculated based on the organic carbon content of the initial glucose, including 89.6% formic acid and 2.6% glycolic acid; the gas phase product was CO 2 , with a yield of 6.1%.

[0084] Embodiment 18

[0085] In this embodiment, glucose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glucose, 0.42mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glucose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glucose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 120°C, the timing was started. After 60 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0086] The results showed that the conversion rate of glucose was 98.4%, and the organic carbon yield of the liquid phase product was 91.5% calculated based on the organic carbon content of the initial glucose, including 88.3% formic acid, 1.2% arabinose, and 2.0% glycolaldehyde; the gas phase product was CO 2 , with a yield of 1.2%.

[0087] Embodiment 19

[0088] In this example, arabinose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g arabinose, 0.42mmol HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of arabinose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in arabinose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 120°C, the timing was started. After the reaction for 1min, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0089] The results showed that the conversion rate of arabinose was 79.8%, and the organic carbon yield of the liquid phase product was 76.1% based on the organic carbon content of the starting arabinose, including 69.5% formic acid and 6.6% ethanolaldehyde; the gas phase product was CO 2 , with a yield of 0.5%.

[0090] Embodiment 20

[0091] In this example, erythrose is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50 mL high temperature and high pressure reactor with magnetic stirring. 0.018 g erythrose, 0.42 mmol HPA-5 and 10 mL of deionized water were added to the reactor (wherein the mass content of erythrose was 0.18 wt%, and the molar ratio of V atoms in HPA-5 to C atoms in erythrose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 120°C, the timing was started. After the reaction for 1 minute, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0092] The results showed that the conversion rate of erythrose was 100%, and the organic carbon yield of the liquid product was 99.0% calculated based on the organic carbon content of the initial erythrose, including 91.6% formic acid and 7.4% ethanolaldehyde; the gaseous product was CO 2 , with a yield of 0.6%.

[0093] Embodiment 21

[0094] In this embodiment, glyceraldehyde is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of glyceraldehyde, 0.42mmol HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of glyceraldehyde was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in glyceraldehyde was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 120°C, the timing was started. After the reaction for 1 minute, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0095] The results showed that the conversion rate of glyceraldehyde was 100%, and the organic carbon yield of the liquid product was 98.9% calculated based on the organic carbon content of the starting glyceraldehyde sugar, including 90.1% formic acid and 8.8% ethanolaldehyde; the gaseous product was CO 2 , with a yield of 0.5%.

[0096] Embodiment 22

[0097] In this example, ethanolaldehyde is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of ethanolaldehyde dimer, 0.42mmol HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of ethanolaldehyde was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in ethanolaldehyde was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 120°C, the timing was started. After the reaction for 1 minute, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gaseous product was discharged into the air bag, the reaction liquid was transferred to a measuring cylinder to determine the volume, and a certain volume of samples of the gaseous product and the liquid product were taken for analysis. The analysis conditions and methods are the same as those in Example 1.

[0098] The results showed that the conversion rate of glycolaldehyde was 92.0%, the liquid product was only formic acid, and the carbon yield of formic acid calculated based on the organic C content of the starting glycolaldehyde was 90.9%; the gaseous product was CO 2 , with a yield of 0.2%.

[0099] Embodiment 23

[0100] In this example, xylan is used as a raw material and HPA-5 is used as a catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of xylan, 0.48mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of xylan was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in xylan was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 160°C, the timing was started. After the reaction for 10 minutes, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor cooled to room temperature, samples were collected for analysis.

[0101] The gas product was discharged into a gas bag and the CO 2 The amount of production. The gas chromatograph used is Agilent 7890A, the chromatographic column is a 50 / 80 Porapak Q column, the detector is TCD, and the carrier gas is helium. The reaction solution is filtered to obtain a residue and a filtrate. The residue is dried and weighed to calculate the mass conversion rate of the raw material. The filtrate is transferred to a measuring cylinder to determine the volume, and a sample is taken for high performance liquid chromatography analysis of the composition. The high performance liquid chromatograph used is Waters 2695, the detector is a differential detector, the chromatographic column is a Shodex SH 1011 carbohydrate chromatographic column, the column temperature is 55°C, the mobile phase is a sulfuric acid aqueous solution with a mass fraction of 0.1wt%, and the flow rate of the mobile phase is 0.5mL / min.

[0102] The results showed that the mass conversion rate of xylan was 100wt%, and the organic carbon yield of the liquid product was 97.3% based on the organic C content of the starting xylan, including 93.9% formic acid and 3.4% acetic acid; the gaseous product was CO 2 , with a yield of 2.7%.

[0103] Embodiment 24

[0104] In this example, cellulose is used as raw material and HPA-5 is used as catalyst to oxidize carbohydrates to prepare formic acid. The carbohydrate oxidation experiment was carried out in a 50mL high-temperature and high-pressure reactor with magnetic stirring. 0.018g of cellulose, 0.47mmol of HPA-5 and 10mL of deionized water were added to the reactor (wherein the mass content of cellulose was 0.18wt%, and the molar ratio of V atoms in HPA-5 to C atoms in cellulose was 3.5), the reactor was sealed, and the air in the reactor was replaced with nitrogen. The reactor was placed in a preheated heating jacket and stirring was turned on. When the reaction temperature reached 180°C, the timing was started. After 60 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. After the reactor cooled to room temperature, samples were collected for analysis. The analysis conditions and methods were the same as those in Example 23.

[0105] The results showed that the mass conversion rate of cellulose was 82.7wt%, and the formic acid yield calculated based on the organic C content of the initial cellulose was 75.1%; the gas phase product was CO 2 , with a yield of 8.8%.

[0106] Embodiment 25

[0107] This example is a step for extracting products after carbohydrate oxidation. First, repeat step (a) of Example 1 to obtain a reaction solution after glucose oxidation, and then use ethyl acetate as an extractant to extract the formic acid product in the reaction solution. The volume ratio of ethyl acetate to the reaction solution is 10, and the extraction is performed 5 times. Then, nitrogen is purged for 10 minutes to remove the introduced ethyl acetate, and the reduced catalyst HPA-5 is obtained. red The aqueous solution is transferred to a measuring cylinder to determine the volume, and a certain volume of sample is taken for analysis. The analysis conditions and methods are the same as in Example 1.

[0108] The results showed that the extraction efficiency of ethyl acetate for formic acid was 93.6% based on the formic acid content in the reaction solution before extraction.

[0109] Embodiment 26

[0110] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. redThe aqueous solution is transferred to a 50mL high-temperature and high-pressure reactor, the reactor is sealed, and then filled with 9.5MPa synthetic air (oxygen partial pressure is 2MPa). The reactor is placed in a preheated heating jacket and stirred. When the reaction temperature reaches 60°C, the timing is started. After the reaction for 10 minutes, the reactor is taken out and quenched with a cold water bath to terminate the reaction. When the reactor is cooled to room temperature, the gas in the reactor is evacuated, the reaction solution is transferred to a measuring cylinder to determine the volume, and a certain volume of sample is taken for analysis. The analysis conditions and methods are the same as in Example 1.

[0111] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.0 after reoxidation, indicating that HPA-5 red All of it has been reoxidized to HPA-5.

[0112] Embodiment 27

[0113] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution is transferred to a 50mL high temperature and high pressure reactor, the reactor is sealed, the air in the reactor is replaced with oxygen, and then 0.5MPa of oxygen is filled. The reactor is placed in a preheated heating jacket and stirred. When the reaction temperature reaches 60°C, the timing is started. After the reaction for 10 minutes, the reactor is taken out and quenched with a cold water bath to terminate the reaction. When the reactor is cooled to room temperature, the gas in the reactor is evacuated, the reaction solution is transferred to a measuring cylinder to determine the volume, and a certain volume of sample is taken for analysis. The analysis conditions and methods are the same as in Example 1.

[0114] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.9 after reoxidation, indicating that HPA-5 was still present in the catalyst solution. red Not reoxidized.

[0115] Embodiment 28

[0116] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution is transferred to a 50mL high temperature and high pressure reactor, the reactor is sealed, the air in the reactor is replaced with oxygen, and then 1MPa of oxygen is filled. The reactor is placed in a preheated heating jacket and stirred. When the reaction temperature reaches 60°C, the timing is started. After the reaction for 10 minutes, the reactor is taken out and quenched with a cold water bath to terminate the reaction. When the reactor is cooled to room temperature, the gas in the reactor is evacuated, the reaction solution is transferred to a measuring cylinder to determine the volume, and a certain volume of sample is taken for analysis. The analysis conditions and methods are the same as in Example 1.

[0117] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.6 after reoxidation, indicating that HPA-5 was still present in the catalyst solution. red Not reoxidized.

[0118] Embodiment 29

[0119] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution is transferred to a 50mL high temperature and high pressure reactor, the reactor is sealed, the air in the reactor is replaced with oxygen, and then 1.5MPa of oxygen is filled. The reactor is placed in a preheated heating jacket and stirred. When the reaction temperature reaches 60°C, the timing is started. After the reaction for 10 minutes, the reactor is taken out and quenched with a cold water bath to terminate the reaction. When the reactor is cooled to room temperature, the gas in the reactor is evacuated, the reaction solution is transferred to a measuring cylinder to determine the volume, and a certain volume of sample is taken for analysis. The analysis conditions and methods are the same as in Example 1.

[0120] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.2 after reoxidation, indicating that HPA-5 was still present in the catalyst solution. red Not reoxidized.

[0121] Embodiment 30

[0122] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution was transferred to a 50mL high temperature and high pressure reactor, the reactor was sealed, the air in the reactor was replaced with oxygen, and then 2.5MPa of oxygen was filled in. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 60°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gas in the reactor was evacuated, the reaction solution was transferred to a measuring cylinder to determine the volume, and a certain volume of sample was taken for analysis. The analysis conditions and methods were the same as in Example 1.

[0123] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.0 after reoxidation, indicating that HPA-5 red All of it has been reoxidized to HPA-5.

[0124] Embodiment 31

[0125] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution was transferred to a 50mL high temperature and high pressure reactor, the reactor was sealed, the air in the reactor was replaced with oxygen, and then 2.0MPa of oxygen was filled in. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 30°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gas in the reactor was evacuated, the reaction solution was transferred to a measuring cylinder to determine the volume, and a certain volume of sample was taken for analysis. The analysis conditions and methods were the same as in Example 1.

[0126] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 1.2 after reoxidation, indicating that HPA-5 was still present in the catalyst solution. red Not reoxidized.

[0127] Embodiment 32

[0128] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution is transferred to a 50mL high temperature and high pressure reactor, the reactor is sealed, the air in the reactor is replaced with oxygen, and then 2.0MPa of oxygen is filled. The reactor is placed in a preheated heating jacket and stirred. When the reaction temperature reaches 40°C, the timing is started. After the reaction for 10 minutes, the reactor is taken out and quenched with a cold water bath to terminate the reaction. When the reactor is cooled to room temperature, the gas in the reactor is evacuated, the reaction solution is transferred to a measuring cylinder to determine the volume, and a certain volume of sample is taken for analysis. The analysis conditions and methods are the same as in Example 1.

[0129] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.8 after reoxidation, indicating that HPA-5 was still present in the catalyst solution. red Not reoxidized.

[0130] Embodiment 33

[0131] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. redThe aqueous solution was transferred to a 50mL high temperature and high pressure reactor, the reactor was sealed, the air in the reactor was replaced with oxygen, and then 2.0MPa of oxygen was filled in. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 50°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gas in the reactor was evacuated, the reaction solution was transferred to a measuring cylinder to determine the volume, and a certain volume of sample was taken for analysis. The analysis conditions and methods were the same as in Example 1.

[0132] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.4 after reoxidation, indicating that HPA-5 was still present in the catalyst solution. red Not reoxidized.

[0133] Embodiment 34

[0134] This example is a step of reoxidation of the catalyst after product extraction. First, repeat steps (a) and (b) of Example 1 to obtain a reduced catalyst HPA-5. red The aqueous solution was transferred to a 50mL high temperature and high pressure reactor, the reactor was sealed, the air in the reactor was replaced with oxygen, and then 2.0MPa of oxygen was filled in. The reactor was placed in a preheated heating jacket and stirred. When the reaction temperature reached 70°C, the timing was started. After 10 minutes of reaction, the reactor was taken out and quenched with a cold water bath to terminate the reaction. When the reactor was cooled to room temperature, the gas in the reactor was evacuated, the reaction solution was transferred to a measuring cylinder to determine the volume, and a certain volume of sample was taken for analysis. The analysis conditions and methods were the same as in Example 1.

[0135] The results showed that the absorbance of the catalyst solution at 750nm in the UV-visible spectrum was 0.0 after reoxidation, indicating that HPA-5 red All of it has been reoxidized to HPA-5.

Claims

1. A method for preparing formic acid by catalytic oxygen oxidation of biomass carbohydrates, the method comprising the following specific steps: (a) Carbohydrate oxidation: Carbohydrate raw materials, oxidized catalyst and water are added into a high-pressure reactor, stirred at a given temperature for reaction, and after the reaction time is reached, the reaction is terminated by cooling; (b) product extraction: extracting the formic acid product in the reaction solution with an extractant, and the raffinate phase is an aqueous solution of the reduced catalyst; (c) Reoxidation of the catalyst: the reduced catalyst aqueous solution is transferred to another high-pressure reactor, filled with oxygen or air, stirred and reacted at a given temperature, and after the reaction time is reached, the reaction liquid is taken out. The reaction liquid is the aqueous solution of the oxidized catalyst and is used for the next round of carbohydrate oxidation; in, The carbohydrate in step (a) is selected from one of glucose, arabinose, erythrose, glyceraldehyde, glycoaldehyde, cellulose and xylan; The mass content of the carbohydrate raw material in the aqueous solution in step (a) is 0.18wt% to 3.6wt%; The catalyst described in step (a) is selected from H5PV2Mo 10 O 40 、H6PV3Mo9O 40 、H7PV4Mo8O 40 、H8PV5Mo7O 40 、H9PV6Mo6O 40 One of; The molar ratio of V atoms in the catalyst to C atoms in the carbohydrate in step (a) is 1 to 4; The temperature of the carbohydrate oxidation reaction in step (a) is 120° C. to 180° C.; The time of the carbohydrate oxidation reaction in step (a) is 1 min to 60 min; The extractant in step (b) is selected from diethyl ether or ethyl acetate, the volume ratio of the extractant to the reaction solution is 10, and the extraction is performed in 3 to 7 times; The initial partial pressure of oxygen in step (c) is 0.5 MPa to 2.5 MPa; The reaction temperature of the catalyst reoxidation in step (c) is 30°C to 70°C; The reaction time of the catalyst reoxidation in step (c) is 10 min.

2. The method according to claim 1, characterized in that The catalyst is H8PV5Mo7O 40 .

3. The method according to claim 1, characterized in that The molar ratio of V atoms in the catalyst to C atoms in the carbohydrate is 3 to 4.

4. The method according to claim 1, characterized in that: The carbohydrate oxidation reaction time is 10 minutes to 60 minutes.

5. The method according to claim 1, characterized in that The initial partial pressure of oxygen in the catalyst reoxidation reaction is 1.5 MPa to 2.5 MPa.

6. The method according to claim 1, characterized in that The reaction temperature of the catalyst reoxidation reaction is 50°C to 70°C.

Images