Application of lithium iron phosphate for lithium battery in catalytic synthesis of 5-hydroxymethylfurfural

Abstract

This invention provides a method for selectively catalytically dehydrating fructose-based or glucose-based carbohydrates into 5-hydroxymethylfurfural using lithium iron phosphate (LiFePO4), an anode material for lithium-ion batteries, as a catalyst. The method includes the following steps: (1) adding a certain amount of LiFePO4 catalyst and reaction medium to a reaction vessel to construct a carbohydrate catalytic dehydration reaction system; (2) adding a certain amount of fructose-based or glucose-based carbohydrates to the reaction system, sealing the reaction vessel, magnetically stirring, heating in an oil bath, and performing a catalytic dehydration reaction at a set temperature to prepare 5-hydroxymethylfurfural; the LiFePO4 catalyst is commercially available LiFePO4 or recycled waste LiFePO4 after the retirement of lithium batteries. This invention fully utilizes the Fe in LiFePO4. 2+ and Li + The catalytic activity of HMF expands the field of recycling retired lithium-ion battery anode materials and increases the selection range of green synthesis catalysts. It has the advantages of being green, environmentally friendly, and having simple recycling methods, and can improve the comprehensive utilization efficiency of waste LiFePO4.

Description

Technical Field

[0001] This invention belongs to the field of high-value utilization technology of anode materials of retired lithium-ion batteries, specifically involving the application of lithium iron phosphate for lithium batteries in the catalytic synthesis of 5-hydroxymethylfurfural. Background Technology

[0002] Lithium-ion batteries, with their high energy density, long cycle life, no radiation, lightweight, low self-discharge, low memory effect, low environmental pollution, and excellent electrochemical stability, have demonstrated immense value in numerous application scenarios and have become a core power source driving the development of modern society, from portable electronic devices and electric vehicles to large-scale energy storage systems and even cutting-edge artificial intelligence hardware. LiFePO4 is one of the typical anode materials for lithium-ion batteries. Its unique olivine structure and controllable electronic properties give it great potential in the field of energy storage, making it a typical power source for mobile devices. For example, lithium-ion batteries, as the "heart" of electric vehicles, are widely used in the electric vehicle field, and their application is showing a rapid year-on-year increase.

[0003] However, the rapid development and application of lithium-ion battery technology also presents new challenges. With the scrapping of numerous lithium-ion electric vehicles and the retirement of a large number of lithium-ion batteries, the power battery recycling market is poised for explosive growth, leading to a more severe accumulation of used lithium-ion batteries. According to forecasts from the Ministry of Industry and Information Technology and several institutions, including China Galaxy Securities Research Institute, the total amount of retired power batteries from passenger and commercial vehicles will approach 7 million tons by 2030, with corresponding amounts of used LiFePO4 batteries exceeding 2 million tons. This massive volume of retired batteries poses a severe challenge to the recycling of LiFePO4 batteries and the reuse of battery materials.

[0004] How to efficiently recycle used lithium-ion batteries, especially to recover valuable metals (Li) from them? + Fe 2+ Reusing (e.g., waste lithium-ion battery anode materials) has become key to solving the aforementioned problems. Faced with these challenges, researchers have conducted extensive work from different perspectives, actively exploring various recycling technologies and methods. These mainly include solid-phase recycling, pyrometallurgical recycling, wet recycling, and direct remediation and regeneration, but most suffer from high costs, cumbersome post-processing, and low metal recycling rates. Therefore, there is an urgent need to develop new, efficient utilization methods for waste lithium-ion battery anode materials.

[0005] Lithium ion (Li +LiFePO4 exhibits weak Lewis (L) acidity and has found some applications in industrial catalysis, particularly demonstrating good catalytic activity in the green catalytic synthesis of 5-hydroxymethylfurfural (HMF). Therefore, applying retired lithium-ion anode materials to the green catalytic synthesis of the biomass-based platform chemical 5-hydroxymethylfurfural will provide a new approach for the comprehensive utilization of waste LiFePO4 anode materials, accelerating the high-value utilization of retired lithium-ion batteries. Summary of the Invention

[0006] To address the aforementioned shortcomings in existing technologies, the present invention aims to provide an application of lithium iron phosphate (LiFePO4) for lithium batteries in the catalytic synthesis of 5-hydroxymethylfurfural. This invention uses LiFePO4 as a catalyst and combines it with an organic solvent to construct a novel catalytic reaction system that selectively catalytically converts fructose- or glucose-based carbohydrates into the important platform chemical 5-hydroxymethylfurfural.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an application of lithium iron phosphate for lithium batteries in the catalytic synthesis of 5-hydroxymethylfurfural, using lithium iron phosphate, a lithium-ion battery anode material, as a catalyst to selectively catalytically dehydrate fructose-based or glucose-based carbohydrates into 5-hydroxymethylfurfural.

[0008] Furthermore, the specific steps include the following:

[0009] (1) A certain amount of lithium iron phosphate catalyst and reaction medium were added to the reactor to construct a carbohydrate catalytic dehydration reaction system;

[0010] (2) A certain amount of fructose-based or glucose-based carbohydrates are added to the reaction system, the reaction vessel is sealed, magnetically stirred, heated in an oil bath, and catalytic dehydration reaction is carried out at a set temperature to prepare 5-hydroxymethylfurfural;

[0011] The lithium iron phosphate catalyst is either commercial lithium iron phosphate used in lithium batteries or recycled lithium iron phosphate from retired lithium batteries.

[0012] The reaction medium is one of the conventional organic solvents.

[0013] Furthermore, the lithium iron phosphate catalyst described in step (1) has a molar fraction of ≤25 mol relative to the sugar basic units in the feedstock.

[0014] Furthermore, the molar volume ratio of the number of basic sugar structural units of the raw material fructose-based or glucose-based carbohydrates to the organic solvent is (25~150) mmol:100 mL.

[0015] Furthermore, the carbohydrate is a monosaccharide, oligosaccharide, or polysaccharide.

[0016] Furthermore, the set temperature in step (2) is 120~200℃.

[0017] Furthermore, the water content in the organic solvent is ≤ 50 mmol / 10 mL.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention studies the catalytic performance of lithium iron phosphate for lithium batteries and finds that it can catalytically dehydrate fructose-based or glucose-based carbohydrates into 5-hydroxymethylfurfural in conventional organic solvents, and exhibits good catalytic activity and stability.

[0020] 2. Compared with existing utilization methods, the direct and efficient utilization method of lithium iron phosphate provided by the present invention has the advantages of being green, environmentally friendly, and simple to recycle, and can improve the comprehensive utilization efficiency of waste lithium iron phosphate.

[0021] 3. The HMF catalytic synthesis reaction system of this invention mainly makes full use of the Fe in lithium iron phosphate. 2+ and Li + The improved catalytic activity broadens the field of recycling retired lithium-ion battery anode materials and increases the selection range of HMF green synthesis catalysts. Attached Figure Description

[0022] Figure 1 Images of commercially available lithium iron phosphate batteries used in digital cameras;

[0023] Figure 2 Photo of a digital camera showing the recycling of lithium iron phosphate batteries after they are retired;

[0024] Figure 3 Graph showing the relationship between fructose concentration and chromatographic peak area obtained by HPLC external standard method;

[0025] Figure 4 A graph showing the relationship between the concentration of HMF obtained by HPLC external standard method and the chromatographic peak area;

[0026] Figure 5 Digital camera photographs of the appearance of the reaction solution at different reaction temperatures (Examples 1 and Examples 14-21);

[0027] Figure 6 Schematic diagram of the process mechanism of LiFePO4 catalyzing the dehydration and conversion of glucose to HMF;

[0028] Figure 7 A digital camera photo of a lithium iron phosphate catalyst after it has been reused 6 times.

[0029] Figure 8 The reusability of lithium iron phosphate catalysts (7) *(Catalytic effect after heat treatment to remove humin)

[0030] Figure 9 XRD diffraction patterns of lithium iron phosphate catalysts (a: LiFePO4 catalyst before use; b: LiFePO4 catalyst after 6 cycles). Detailed Implementation

[0031] The method of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. In the present invention, lithium iron phosphate is abbreviated as LiFePO4, and 5-hydroxymethylfurfural can be abbreviated as HMF.

[0032] I. An application of lithium iron phosphate for lithium batteries in the catalytic synthesis of 5-hydroxymethylfurfural.

[0033] Example 1

[0034] An application of lithium iron phosphate for lithium batteries in the catalytic synthesis of 5-hydroxymethylfurfural, the specific steps of which are as follows:

[0035] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product (see [link to product]). Figure 1 The solvent is isopropanol (i-PrOH).

[0036] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170℃ for 2 h.

[0037] Example 2

[0038] 1) The catalyst used in this embodiment is recovered decommissioned LiFePO4 (see Figure 2 The solvent is isopropanol (i-PrOH).

[0039] 2) Add 1.80 g fructose (10 mmol), 0.31 g recovered LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2 h.

[0040] Example 3

[0041] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is methanol;

[0042] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL methanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2 h.

[0043] Example 4

[0044] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is ethanol;

[0045] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL ethanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm) and heat in an oil bath at 170 °C for 2 h.

[0046] Example 5

[0047] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is n-propanol;

[0048] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL n-propanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170°C for 2 h.

[0049] Example 6

[0050] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is n-butanol;

[0051] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL n-butanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2 h.

[0052] Example 7

[0053] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is isobutanol;

[0054] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL n-butanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2 h.

[0055] Example 8

[0056] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is tetrahydrofuran;

[0057] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL tetrahydrofuran to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2 h.

[0058] Example 9

[0059] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, and the solvent is γ-valerolactone;

[0060] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL γ-valerol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170℃ for 2 h.

[0061] Example 10

[0062] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, the solvent is isopropanol, and the catalyst dosage is 5 mol%.

[0063] 2) Add 1.80 g fructose (10 mmol), 0.08 g LiFePO4 (0.5 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170°C for 2 h.

[0064] Example 11

[0065] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, the solvent is isopropanol, and the catalyst dosage is 10 mol%.

[0066] 2) Add 1.80 g fructose (10 mmol), 0.16 g LiFePO4 (1.0 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170°C for 2 h.

[0067] Example 12

[0068] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, the solvent is isopropanol, and the catalyst dosage is 15 mol%.

[0069] 2) Add 1.80 g fructose (10 mmol), 0.23 g LiFePO4 (1.5 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170°C for 2 h.

[0070] Example 13

[0071] 1) The catalyst used in this embodiment is a commercially available LiFePO4 product, the solvent is isopropanol, and the catalyst dosage is 25 mol%;

[0072] 2) Add 1.80 g fructose (10 mmol), 0.39 g LiFePO4 (2.5 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170°C for 2 h.

[0073] Example 14

[0074] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 120 ℃.

[0075] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 120 °C for 2 h.

[0076] Example 15

[0077] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 130 ℃.

[0078] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 130 °C for 2 h.

[0079] Example 16

[0080] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 140 ℃.

[0081] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 140 °C for 2 h.

[0082] Example 17

[0083] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 150 ℃.

[0084] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 150 °C for 2 h.

[0085] Example 18

[0086] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 160 ℃.

[0087] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 160℃ for 2 h.

[0088] Example 19

[0089] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 180 ℃.

[0090] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 180°C for 2 h.

[0091] Example 20

[0092] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 190 ℃.

[0093] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 190℃ for 2 h.

[0094] Example 21

[0095] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, and the reaction temperature is 200 ℃.

[0096] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 200℃ for 2 h.

[0097] Example 22

[0098] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, and the reaction time is 0.5 h.

[0099] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 0.5 h.

[0100] Example 23

[0101] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, and the reaction time is 1.0 h.

[0102] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 1.0 h.

[0103] Example 24

[0104] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, and the reaction time is 1.5 h.

[0105] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 1.5 h.

[0106] Example 26

[0107] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, and the reaction time is 2.5 h.

[0108] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.5 h.

[0109] Example 26

[0110] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, and the reaction time is 3.0 h.

[0111] 2) Add 1.80 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 3.0 h.

[0112] Example 27

[0113] 1) The catalyst used in this example is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the fructose dosage is 2.5 mmol.

[0114] 2) Add 0.45 g fructose (2.5 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0115] Example 28

[0116] 1) The catalyst used in this example is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the fructose dosage is 5.0 mmol.

[0117] 2) Add 0.9 g fructose (5.0 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0118] Example 29

[0119] 1) The catalyst used in this example is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the fructose dosage is 7.5 mmol.

[0120] 2) Add 1.35 g fructose (7.5 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0121] Example 30

[0122] 1) The catalyst used in this example is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the fructose dosage is 12.5 mmol.

[0123] 2) Add 2.25 g fructose (12.5 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170℃ for 2.0 h.

[0124] Example 31

[0125] 1) The catalyst used in this example is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the fructose dosage is 15.0 mmol.

[0126] 2) Add 2.7 g fructose (15.0 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0127] Example 32

[0128] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, the raw material is glucose, and the dosage is 10 mmol.

[0129] 2) Add 1.8 g glucose (10 mmol), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0130] Example 33

[0131] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the raw material is sucrose.

[0132] 2) Add 1.71 g sucrose (10 mmol monosaccharide structural units), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0133] Example 34

[0134] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the raw material is inulin (fructan).

[0135] 2) Add 1.62 g inulin (10 mmol monosaccharide structural units), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0136] Example 35

[0137] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the raw material is starch.

[0138] 2) Add 1.62 g starch (10 mmol monosaccharide structural units), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0139] Example 36

[0140] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, and the raw material is cellulose.

[0141] 2) Add 1.62 g cellulose (10 mmol monosaccharide structural units), 0.31 g LiFePO4 (2 mmol), and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0142] Example 37

[0143] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, fructose is used as a material, and the amount of water added is 10 mmol.

[0144] 2) Add 1.8 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), 10 mL isopropanol, and 0.18 g (10 mmol) of deionized water to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0145] Example 38

[0146] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, fructose is used as a material, and the amount of water added is 20 mmol.

[0147] 2) Add 1.8 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), 10 mL isopropanol, and 0.36 g (20 mmol) of deionized water to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0148] Example 39

[0149] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, fructose is used as a material, and the amount of water added is 30 mmol.

[0150] 2) Add 1.8 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), 10 mL isopropanol, and 0.54 g (30 mmol) of deionized water to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0151] Example 40

[0152] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, fructose is used as a material, and the amount of water added is 40 mmol.

[0153] 2) Add 1.8 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), 10 mL isopropanol, and 0.72 g (40 mmol) of deionized water to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0154] Example 41

[0155] 1) The catalyst used in this embodiment is a commercial LiFePO4 product, the solvent is isopropanol, the catalyst dosage is 20 mol%, the reaction temperature is 170 ℃, the reaction time is 2.0 h, fructose is used as a material, and the amount of water added is 50 mmol.

[0156] 2) Add 1.8 g fructose (10 mmol), 0.31 g LiFePO4 (2 mmol), 10 mL isopropanol, and 0.90 g (50 mmol) of deionized water to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2.0 h.

[0157] Example 42

[0158] 1) The catalyst used in this embodiment is the LiFePO4 catalyst recovered in Example 1, and other reaction conditions are the same as in Example 1;

[0159] 2) Add 1.80 g fructose (10 mmol), recovered LiFePO4, and 10 mL isopropanol to a 25 mL hydrothermal reactor. After sealing the reactor, stir magnetically (650 rpm), heat in an oil bath, and react at 170 °C for 2 h.

[0160] II. Sample Analysis

[0161] After the reaction was completed, the lithium iron phosphate catalyst was separated and washed using a high-speed centrifuge (8000 rpm). The reaction solution and washing solution were then transferred to a 100 mL volumetric flask and diluted to volume with deionized water. The diluted solution was then filtered through a 0.22 μm microporous membrane and quantitatively analyzed using a high-performance liquid chromatograph (HPLC, Agilent 1200) (external standard method).

[0162] The analytical conditions for residual fructose content were as follows: HPX-87H column (300 × 7.8 mm, 5 μm), 5 mM H2SO4 solution as mobile phase, flow rate of 0.6 mL / min, column temperature of 65℃, differential detector (RID), and injection volume of 20 μL.

[0163] HMF content analysis method conditions: C18 reversed-phase column (250 × 4.6 mm, 5 μm), 25% methanol aqueous solution as mobile phase (CH3OH / H2O, volume ratio 1:4), flow rate 0.6 mL / min, column temperature 30℃, ultraviolet detector (UV), detection wavelength 284 nm, injection volume 20 μL.

[0164] Standard curves were established using the peak areas of fructose and HMF standards at different concentrations during HPLC analysis (e.g., Figure 3 and Figure 4 The conversion rate (Conv., mol%) and HMF yield (Y) can be calculated by measuring the peak area of ​​the sample in HPLC and using the corresponding standard curve.HMF (mol%) and the corresponding selectivity (S) HMF (mol%). The calculation formula is shown in 1-3.

[0165] (1)

[0166] (2)

[0167] (3)

[0168] In the formula n RF n F These represent the number of moles of fructose remaining in the reaction system and the number of moles of fructose added at the start of the reaction, respectively; n HMF This represents the number of moles of HMF generated during the reaction.

[0169] Table 1 shows the effect of the reaction medium on the catalytic fructose dehydration performance of LiFePO4 in Examples 1-9.

[0170]

[0171] As shown in Table 1, the reaction medium has a significant impact on the performance of LiFePO4 in catalyzing the dehydration of fructose to form HMF (Examples 1-7), indicating that monohydric alcohols are beneficial to the conversion of fructose to HMF to a certain extent, especially the bulky isopropanol (i-PrOH) and isobutanol (i-BuOH) (Examples 1 and 7). Furthermore, when aprotic solvents tetrahydrofuran and γ-valerol are used as reaction media, fructose can also form HMF under the catalysis of LiFePO4 (Examples 8 and 9), indicating that the LiFePO4 catalyst has good solvent compatibility in catalyzing the dehydration of fructose to form HMF. Meanwhile, waste (retired) LiFePO4 recovered from decommissioned lithium batteries also exhibits good catalytic activity (Example 2), achieving a fructose dehydration to HMF yield of 38.9%, comparable to the catalytic activity of fresh LiFePO4 (Example 1).

[0172] Table 2 shows the effect of LiFePO4 catalyst dosage on fructose dehydration performance in Examples 10-13.

[0173]

[0174] As shown in Table 2, the conversion rate of fructose gradually increased with the increase of LiFePO4 catalyst dosage (Examples 1 and 10-13). When the catalyst dosage was 25 mol%, the fructose conversion rate reached 97.0%, indicating that the catalyst dosage had a significant impact on the dehydration conversion efficiency of fructose (Example 13). The HMF yield also increased with the increase of catalyst dosage. When the LiFePO4 dosage was 25 mol%, the HMF yield reached 34.3%, indicating that increasing the catalyst dosage was beneficial for accelerating HMF formation. However, the selectivity of HMF showed a trend of first increasing and then decreasing with increasing catalyst dosage, indicating that the presence of a large amount of catalyst could also accelerate the occurrence of side reactions and reduce the directional conversion efficiency of fructose to HMF (Examples 1 and 11-13).

[0175] Table 3 shows the effect of temperature on the dehydration performance of fructose in Examples 14-21.

[0176]

[0177] As shown in Table 3, fructose can be converted at a reaction temperature of 120 °C, but the efficiency of HMF formation is low. The fructose conversion rate is 38.7%, while the HMF yield is only 0.4% (Example 14). This is mainly because the conversion of fructose to HMF requires the removal of three water molecules. Under low temperature conditions, fructose only undergoes partial dehydration to form an intermediate, without deep dehydration to form HMF. When the reaction temperature is gradually increased to 170 °C, the fructose conversion rate, HMF yield, and selectivity all show a gradual upward trend. At 170 °C, the fructose conversion rate, HMF yield, and selectivity reach 83.0%, 33.8%, and 40.7%, respectively, indicating that high temperature is beneficial for accelerating the fructose dehydration reaction (Example 1). However, as the reaction temperature continued to increase, the fructose conversion rate continued to increase, but the HMF yield and selectivity both showed a rapid downward trend (Examples 19-21). When the temperature reached 200 °C, the fructose conversion rate was >95%, while the HMF yield and selectivity decreased to 10.4% and 10.9%, respectively. This indicates that high temperature can also accelerate the occurrence of side reactions, forming insoluble byproducts such as humin, which is detrimental to the stability of HMF. Figure 5 ).

[0178] Table 4 shows the effect of time on fructose dehydration performance in Examples 22-26.

[0179]

[0180] As shown in Table 4, the fructose conversion rate and HMF yield increased with increasing reaction time (Examples 1 and Examples 22-26). At a reaction time of 0.5 h, the fructose conversion rate was 53.0% and the HMF yield was 22.3%. When the reaction time was extended to 3.0 h, the fructose conversion rate and HMF yield reached 91.1% and 34.8%, respectively, indicating that extending the reaction time was beneficial for HMF formation. Furthermore, the results showed that extending the reaction time had little effect on HMF selectivity, maintaining it at around 40%, but exhibiting a slow overall decreasing trend. This result suggests that the HMF generated during the reaction may undergo side reactions under the action of the catalyst to form byproducts such as humic acid.

[0181] Table 5 shows the effect of substrate addition amount and type on Examples 27-36.

[0182]

[0183] As shown in Table 5, the fructose conversion rate gradually increased with the increase of the initial fructose dosage, while the HMF yield and selectivity decreased. When the fructose dosage was 2.5 mmol, the fructose conversion rate was 74.6%, and the HMF yield and selectivity were 36.0% and 48.3%, respectively (Example 27). When the fructose dosage increased to 15 mmol, the fructose conversion rate reached 90.8%, while the HMF yield and selectivity decreased to 25.5% and 28.1%, respectively (Example 31). This is mainly because the increase in the amount of raw materials led to an increase in the content of intermediates and HMF in the reaction system, thereby accelerating the probability of side reactions between "fructose-fructose", "fructose-HMF", "fructose-intermediate", "HMF-intermediate", "HMF-HMF", and "intermediate-intermediate". Furthermore, this LiFePO4 catalyst can also catalyze the conversion of carbohydrates containing glucose and fructose structural units into HMF (Examples 32-36), especially those containing fructose structural units, indicating that the catalyst system has good substrate versatility. The mechanism of LiFePO4 catalyzing the dehydration of glucose to HMF is as follows: Figure 6 As shown, (1) when glucose-based carbohydrates are used as raw materials, the divalent iron ions (Fe) in lithium iron phosphate (LiFePO4) 2+ ) catalyzes the isomerization of glucose to fructose, while weakly acidic lithium ions (Li) + (1) It catalyzes the continuous removal of three water molecules from fructose to generate HMF; (2) When fructose-based carbohydrates are used as materials, weakly acidic lithium ions (Li+) are the main active centers, used to catalyze the continuous removal of three water molecules from fructose. This fully reflects the presence of divalent iron ions (Fe) in LiFePO4. 2+ ) and lithium ions (Li + Synergistic catalytic characteristics of the active center.

[0184] Table 6. Effect of water content in the reaction system

[0185]

[0186] As shown in Table 6, the efficiency of fructose conversion to HMF first increases and then decreases as the water content in the reaction system gradually increases (Examples 1 and Examples 37-41). When the water content is 20 mmol, the fructose conversion rate reaches its maximum (85.9%) (Example 38); when the water content is further increased to 50 mmol, the fructose conversion rate decreases by 65.8% (Example 41); the HMF yield and selectivity reach their maximum at a water content of 10 mmol, at 36.4% and 43.2%, respectively (Example 37); when the water content is further increased to 50 mmol, the HMF yield and selectivity rapidly decrease to 18.9% and 28.6%, respectively (Example 41). The experimental results indicate that the presence of a small amount of water is beneficial to the conversion of fructose to HMF, mainly because a small amount of water can partially dissociate into protons (H+) under subcritical conditions. + This increases the acid strength of the reaction system, thereby accelerating the conversion of fructose to HMF. When the water content is high, the inhibitory effect of water on the fructose dehydration reaction is greater than that of protons (H+). + The water content accelerates the dehydration of fructose, resulting in high water content and low fructose conversion efficiency. However, overall, when the water content is ≤10 mmol, the dehydration conversion efficiency of fructose is not significantly reduced, indicating that the "LiFePO4-isopropanol" catalytic system has a certain degree of water resistance. Furthermore, when using commercial isopropanol as a solvent, excessive drying is not required, which improves the practicality of this catalytic system in the HMF synthesis process.

[0187] Reusability of LiFePO4 catalyst: After the reaction in Example 1, the catalyst was recovered and reused using high-speed centrifugation. The catalyst was reused under the same reaction conditions as in Example 1. The catalyst after six reuses showed... Figure 7 As shown.

[0188] from Figure 8 The results show that the catalytic activity of the LiFePO4 catalyst decreased slightly (31.6%) after four reuses, and the HMF yield decreased to 26.6% after six more reuses. The decrease in LiFePO4 catalytic activity may be due to the formation of a large amount of humin byproducts during the reaction, which adsorb onto the surface of the LiFePO4 catalyst, reducing its contact efficiency with fructose and thus inhibiting its catalytic activity. After six reuses, the catalyst's appearance changed from a grayish-black powder to a yellowish-brown powder. Figure 7Furthermore, the humin was removed by a simple heat treatment (muffle furnace calcination, 600 ℃, 2 h), and the catalytic activity was restored to its original state. XRD showed that the crystal structure of the LiFePO4 catalyst did not change significantly before and after use. Figure 9 This further demonstrates that LiFePO4 exhibits good structural stability in the catalytic dehydration of fructose to HMF, and also indicates that this catalyst has good application value in the catalytic synthesis of HMF.

[0189] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An application of lithium iron phosphate for lithium batteries in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, Using lithium iron phosphate, a lithium-ion battery anode material, as a catalyst, fructose-based or glucose-based carbohydrates are selectively dehydrated and converted into 5-hydroxymethylfurfural.

2. The application of lithium iron phosphate for lithium batteries according to claim 1 in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, Specifically, the steps include the following: (1) A certain amount of lithium iron phosphate catalyst and reaction medium were added to the reactor to construct a carbohydrate catalytic dehydration reaction system; (2) A certain amount of fructose-based or glucose-based carbohydrates are added to the reaction system, the reaction vessel is sealed, magnetically stirred, heated in an oil bath, and catalytic dehydration reaction is carried out at a set temperature to prepare 5-hydroxymethylfurfural; The lithium iron phosphate catalyst is either commercial lithium iron phosphate used in lithium batteries or recycled lithium iron phosphate from retired lithium batteries. The reaction medium is one of the conventional organic solvents.

3. The application of lithium iron phosphate for lithium batteries according to claim 2 in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, The lithium iron phosphate catalyst described in step (1) has a molar fraction of ≤ 25 mol relative to the sugar basic units in the feedstock.

4. The application of lithium iron phosphate for lithium batteries according to claim 2 in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, The molar volume ratio of the number of basic sugar structural units of the raw material fructose-based or glucose-based carbohydrates to the organic solvent is (25~150) mmol:100 mL.

5. The application of lithium iron phosphate for lithium batteries according to claim 2 in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, The carbohydrate is a monosaccharide, oligosaccharide, or polysaccharide.

6. The application of lithium iron phosphate for lithium batteries according to claim 2 in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, The set temperature in step (2) is 120~200℃.

7. The application of lithium iron phosphate for lithium batteries according to claim 2 in the catalytic synthesis of 5-hydroxymethylfurfural, characterized in that, The organic solvent contains ≤ 50 mmol / 10 mL of water.

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