Preparation method and application of metal-free catalyst for constructing FLPs on surface of biomass derived carbon material

Abstract

The invention discloses a preparation method and application of a metal-free catalyst for constructing FLPs on the surface of a biomass derived carbon material. The all-solid-state FLPs metal-free catalyst is prepared by taking a biomass derived carbon material as a substrate, and is applied to a reaction for preparing unsaturated alcohol by hydrogenation of alpha, beta-unsaturated aldehyde. Due to existence of FLPs sites, small molecules such as H2 can be activated, carbonyl in alpha, beta-unsaturated aldehyde can be effectively adsorbed, directional conversion from alpha, beta-unsaturated aldehyde to unsaturated alcohol is achieved, and the yield of unsaturated alcohol is increased. In addition, the constructed FLPs has no metal catalyst, metal use is avoided, the problem of metal leaching is solved, the stability of the catalyst is improved, and a good catalytic effect is achieved. The preparation method is simple, the production cost is low, the hydrogenation effect is considerable, and the catalyst is environmentally friendly, does not cause secondary pollution to the environment, and can be widely applied to hydrogenation reactions of various alpha, beta-unsaturated aldehydes.

Description

Technical Field

[0001] The present invention relates to the field of catalyst preparation, and in particular to a preparation method and application of a FLPs metal-free catalyst constructed on the surface of a biomass-derived carbon material. Background Art

[0002] As an important renewable carbon source, biomass resources are increasingly valued for their high-value utilization due to their advantages such as low cost and wide availability. Converting biomass into high-value-added chemicals and biofuels not only helps alleviate the energy crisis, but also effectively solves the environmental problems caused by excessive agricultural and forestry waste. Among them, α,β-unsaturated aldehydes (such as furfural) are an important class of biomass-derived platform compounds, and their hydrogenated products, α,β-unsaturated alcohols (such as furfuryl alcohol), are widely used in the fields of medicine, fragrances, and fine chemicals. However, taking furfural as an example, the active aldehyde group and furan ring in its molecule are prone to side reactions (such as the formation of tetrahydrofurfuryl alcohol or 2-methylfuran), resulting in a significant decrease in the selectivity of the target product furfuryl alcohol.

[0003] The current hydrogenation methods for α,β-unsaturated aldehydes mainly include:

[0004] (1) Chemical reduction method: It requires the use of excessive reducing agents, which has disadvantages such as high cost, difficulty in product separation and pollution risk;

[0005] (2) Catalytic hydrogenation: Although it has advantages such as high atomic utilization and environmental friendliness, the existing catalyst system has obvious limitations, which are specifically reflected in:

[0006] (a) Metal catalysts (precious metals Pt / Pd / Ru or non-precious metals Ni / Co / Cu): Although metal catalysts generally have good activity (e.g., J. Am. Chem. Soc. 2019, 141, 11353-11357), metal leaching during the reaction is inevitable, leading to catalyst instability, product contamination, and even health hazards;

[0007] (b) Metal-free catalysts: excellent stability but generally insufficient activity.

[0008] Frustrated Lewis acid-base pairs (FLPs) are considered a potential solution due to their ability to activate small molecules (such as H2 and CO2). However, existing FLPs catalysts still face the following challenges:

[0009] (1) Homogeneous FLPs (e.g., Science 2006, 314, 1124-1126): They require sacrificial agents such as borane, which are costly and difficult to purify (e.g., Chinese invention CN112961268A has problems such as expensive preparation and difficult recycling);

[0010] (2) Heterogeneous FLPs: For example, the B,N-FLPs catalyst constructed on reduced graphene oxide by Liu et al. (J.Am.Chem.Soc.2025,147,3840-3854.) can achieve a cinnamaldehyde hydrogenation yield of 97.2%, but it relies on a high-priced substrate and a complex preparation process, which restricts its large-scale application.

[0011] In summary, metal leaching contamination, difficulty in homogeneous system recovery, and high cost of heterogeneous supports are the main drawbacks of current technologies. There is an urgent need to develop a heterogeneous FLPs metal-free catalyst that combines high activity, high selectivity, low cost, and environmental friendliness to meet the industrial demand for green hydrogenation of α,β-unsaturated aldehydes. Summary of the Invention

[0012] To address technical issues such as metal leaching pollution, difficulty in homogeneous system recovery, and high heterogeneous carrier costs associated with existing α,β-unsaturated aldehyde production methods, the present invention provides a method for preparing a metal-free FLPs catalyst constructed on the surface of a biomass-derived carbon material and its application. This catalyst utilizes inexpensive biomass-derived carbon materials as a carbon source, resulting in an all-solid-state heterogeneous FLPs metal-free catalyst. This low-cost, environmentally friendly catalyst avoids the use of metals, reducing production costs while also improving catalyst stability. It demonstrates excellent catalytic effectiveness in the hydrogenation of α,β-unsaturated aldehydes to produce unsaturated alcohols.

[0013] The technical solution adopted in the present invention is as follows:

[0014] A method for preparing a metal-free FLPs catalyst on the surface of a biomass-derived carbon material comprises the following steps:

[0015] S1. The biomass carbon source is calcined under a nitrogen atmosphere, washed, and dried to obtain a biomass-derived carbon material;

[0016] S2. The carbon material obtained in step S1 is ground and mixed with an etchant, and then calcined and washed to obtain a defective carbon material;

[0017] S3. Grind and mix the defective carbon material obtained in step S2 with a nitrogen source and a boron source, and then calcine, wash, and dry the mixture in stages to obtain a FLPs metal-free catalyst.

[0018] Furthermore, in step S1, the biomass carbon source includes at least one of sugars, organic acids, oils and fats, or alcohols; preferably, microcrystalline cellulose, soluble starch, glucose, citric acid, resorcinol, or polyethylene glycol-6000.

[0019] Furthermore, in step S1, the calcination conditions are: heating to 300-400°C at 1-3°C / min, then heating to 700-900°C at 3-5°C / min and keeping the temperature for 1-3 hours.

[0020] Furthermore, in step S2, the etchant is KOH, NH4HCO3 or NH4CO3; the mass ratio of the carbon material to the etchant is 1:6-10, preferably 1:8-9.

[0021] Furthermore, in step S2, the calcination conditions are: heating to 450-550°C at a rate of 3-5°C / min and keeping the temperature for 2-4 hours.

[0022] Furthermore, in step S3, the nitrogen source is sodium amide, dicyandiamide, dicyandiamide, melamine, urea or triethylenediamine, preferably sodium amide, and the boron source is sodium borohydride, metaboric acid, boric acid or phenylboric acid, preferably sodium borohydride; the mass ratio of the defective carbon material, the nitrogen source and the boron source is 1:1~3:1~3.

[0023] Furthermore, in step S3, the staged calcination conditions are: heating to 450-550° C. at 3-5° C. / min and keeping warm for 0.5-2 h, then heating to 850° C. at 3-5° C. / min and keeping warm for 2 h.

[0024] Furthermore, the FLPs metal-free catalyst is a defective carbon material co-doped with B and N, having FLPs active sites; preferably DE-MCC-B3N3, DE-STH-B3N3, DE-GLU-B3N3, DE-CA-B3N3, DE-ROL-B3N3 or DE-PEG-B3N3.

[0025] The FLPs metal-free catalyst is used in the selective hydrogenation of α,β-unsaturated aldehydes to prepare unsaturated alcohols; the α,β-unsaturated aldehyde is furfural.

[0026] Further, the reaction conditions are:

[0027] Reaction temperature: 140-170°C;

[0028] Hydrogen pressure: 0.5~3MPa;

[0029] Reaction solvent: ethanol, methanol or isopropanol, preferably isopropanol;

[0030] The mass ratio of the catalyst to the α,β-unsaturated aldehyde (such as furfural) is 1:0.5-1.5.

[0031] The beneficial effects of the present invention are:

[0032] (1) The present invention uses cheap and readily available biomass carbon sources (such as microcrystalline cellulose, starch, glucose, etc.) to replace expensive graphene substrates, and combines a simple pyrolysis-etching-doping process to significantly reduce the preparation cost of all-solid-state FLPs metal-free catalysts, thereby solving the defect of existing FLPs catalysts that rely on precious metals or high-priced carbon substrates.

[0033] (2) The catalyst obtained by the present invention is completely free of metal components, which fundamentally eliminates the product pollution, catalyst deactivation and health hazards caused by metal leaching, while improving the long-term stability of the catalyst.

[0034] (3) The unique B / N co-doped FLPs site design of the present invention (such as DE-MCC-B3N3) can simultaneously activate H2 molecules and specifically adsorb the carbonyl groups of α,β-unsaturated aldehydes, achieving nearly 100% furfural conversion and 99.8% furfuryl alcohol selectivity under mild conditions (160℃, 2MPa H2), which is superior to most non-precious metal catalysts.

[0035] (4) The preparation process of the present invention does not require toxic solvents or sacrificial agents, and the reaction by-product is only water; the catalyst can be adapted to a variety of biomass carbon sources and different α, β-unsaturated aldehyde substrates, and has the potential for large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the full XPS spectrum of DE-MCC-B3N3 catalyst;

[0037] Figure 2 FLPs catalyst verification experiment. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] Example 1

[0040] A method for preparing a metal-free FLPs catalyst on the surface of a biomass-derived carbon material comprises the following steps:

[0041] (1) A certain amount of microcrystalline cellulose is placed in a tube furnace, and nitrogen is injected into the tube furnace to remove the air in the tube;

[0042] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0043] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a microcrystalline cellulose-derived carbon material, which was designated as MCC;

[0044] (4) Grind and mix the MCC obtained in step (3) with KOH in a mass ratio of 1 / 9;

[0045] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0046] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-MCC;

[0047] (7) DE-MCC was ground and mixed with sodium amide and sodium borohydride in a mass ratio of 1:3:3;

[0048] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0049] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH = 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-MCC-B3N3.

[0050] Specific operation steps for the selective hydrogenation of furfural using DE-MCC-B3N3 catalyst:

[0051] (1) Weigh 0.1 g of DE-MCC-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0052] (2) After the reactor is sealed and leak-checked, the air in the reactor is evacuated with a vacuum pump and evacuated to a vacuum state. The air is then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0053] (3) Set the reaction conditions and start heating;

[0054] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0055] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0056] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0057] Figure 1The full XPS spectrum of the DE-MCC-B3N3 catalyst is shown. Characteristic peaks of boron and nitrogen were detected in the full XPS spectrum, indicating the successful doping of boron and nitrogen into DE-MCC, creating BCN FLPs sites with boron as a Lewis acid site and nitrogen as a Lewis base site. Consequently, this catalyst exhibits excellent catalytic performance for the highly selective hydrogenation of furfural to furfuryl alcohol.

[0058] Figure 2 Figure 2 shows FLPs catalyst validation experiments. To verify the formation of the FLPs catalyst, a series of pyrrole / pyridine validation experiments were conducted. The results showed that the addition of a certain amount of pyrrole / pyridine significantly inhibited the furfural hydrogenation reaction, indicating that the FLPs sites were poisoned and inactivated. Therefore, the successful synthesis of the FLPs catalyst was confirmed.

[0059] Example 2

[0060] A preparation method for constructing FLPs metal-free catalyst on the surface of biomass-derived carbon material

[0061] (1) A certain amount of soluble starch is placed in a tube furnace, and nitrogen is filled into the tube furnace to remove the air in the tube;

[0062] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0063] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a soluble starch-derived carbon material, which was denoted as STH;

[0064] (4) Grind and mix the STH obtained in step (3) with KOH in a mass ratio of 1 / 9;

[0065] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0066] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-STH;

[0067] (7) DE-STH was ground and mixed with sodium amide and sodium borohydride in a mass ratio of 1:3:3;

[0068] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0069] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH = 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-STH-B3N3.

[0070] Specific operation steps for the selective hydrogenation of furfural using DE-STH-B3N3 catalyst:

[0071] (1) Weigh 0.1 g of DE-STH-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0072] (2) After the reactor was sealed and leak-checked, the air in the reactor was evacuated using a vacuum pump and evacuated to a vacuum. The atmosphere was then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0073] (3) Set the reaction conditions and start heating;

[0074] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0075] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0076] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0077] Example 3

[0078] A preparation method for constructing FLPs metal-free catalyst on the surface of biomass-derived carbon material

[0079] (1) Place a certain amount of glucose in a tube furnace and fill the tube furnace with nitrogen to remove the air in the tube;

[0080] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0081] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain glucose-derived carbon material, which was denoted as GLU;

[0082] (4) GLU and KOH obtained in step (3) were ground and mixed in a mass ratio of 1 / 9;

[0083] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0084] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-GLU;

[0085] (7) DE-GLU was ground and mixed with sodium amide and sodium borohydride in a mass ratio of 1:3:3;

[0086] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0087] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH was 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-GLU-B3N3.

[0088] Specific operation steps for the selective hydrogenation of furfural using DE-GLU-B3N3 catalyst:

[0089] (1) Weigh 0.1 g of DE-GLU-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0090] (2) After the reactor was sealed and leak-checked, the air in the reactor was evacuated using a vacuum pump and evacuated to a vacuum. The atmosphere was then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0091] (3) Set the reaction conditions and start heating;

[0092] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0093] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0094] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0095] Example 4

[0096] A preparation method for constructing FLPs metal-free catalyst on the surface of biomass-derived carbon material

[0097] (1) Place a certain amount of citric acid in a tube furnace and fill the tube furnace with nitrogen to remove the air in the tube;

[0098] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0099] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a citric acid-derived carbon material, denoted as CA;

[0100] (4) Grind and mix the CA obtained in step (3) with KOH in a mass ratio of 1 / 9;

[0101] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0102] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-CA;

[0103] (7) DE-CA was ground and mixed with sodium amide and sodium borohydride in a mass ratio of 1:3:3;

[0104] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0105] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH = 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-CA-B3N3.

[0106] Specific operation steps for the selective hydrogenation of furfural using DE-CA-B3N3 catalyst:

[0107] (1) Weigh 0.1 g of DE-CA-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0108] (2) After the reactor was sealed and leak-checked, the air in the reactor was evacuated using a vacuum pump and evacuated to a vacuum. The atmosphere was then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0109] (3) Set the reaction conditions and start heating;

[0110] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0111] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0112] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0113] Example 5

[0114] A preparation method for constructing FLPs metal-free catalyst on the surface of biomass-derived carbon material

[0115] (1) A certain amount of resorcinol is placed in a tube furnace, and nitrogen is filled into the tube furnace to remove the air in the tube;

[0116] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0117] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain the resorcinol-derived carbon material, which was recorded as ROL;

[0118] (4) Grind and mix the ROL obtained in step (3) with KOH in a mass ratio of 1:3:3;

[0119] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0120] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-ROL.

[0121] (7) Grind and mix DE-ROL, sodium amide, and sodium borohydride in a mass ratio of 1 / 3;

[0122] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0123] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH was 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-ROL-B3N3.

[0124] Specific operation steps for the selective hydrogenation of furfural using DE-ROL-B3N3 catalyst:

[0125] (1) Weigh 0.1 g of DE-ROL-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0126] (2) After the reactor was sealed and leak-checked, the air in the reactor was evacuated using a vacuum pump and evacuated to a vacuum. The atmosphere was then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0127] (3) Set the reaction conditions and start heating;

[0128] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0129] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0130] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0131] Example 6

[0132] A preparation method for constructing FLPs metal-free catalyst on the surface of biomass-derived carbon material

[0133] (1) Place a certain amount of polyethylene glycol-6000 in a tube furnace and fill the tube furnace with nitrogen to remove the air in the tube;

[0134] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0135] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain polyethylene glycol-6000-derived carbon material, denoted as PEG;

[0136] (4) Grind and mix the PEG and KOH obtained in step (3) at a mass ratio of 1 / 9;

[0137] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0138] (6) The solid powder taken out from the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was designated as DE-PEG;

[0139] (7) DE-PEG was ground and mixed with sodium amide and sodium borohydride in a mass ratio of 1:3:3;

[0140] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0141] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH = 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-PEG-B3N3.

[0142] Specific operation steps for the selective hydrogenation of furfural using DE-PEG-B3N3 catalyst:

[0143] (1) Weigh 0.1 g of DE-PEG-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0144] (2) After the reactor was sealed and leak-checked, the air in the reactor was evacuated using a vacuum pump and evacuated to a vacuum. The atmosphere was then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0145] (3) Set the reaction conditions and start heating;

[0146] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0147] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0148] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0149] Comparative Example 1

[0150] (1) A certain amount of microcrystalline cellulose is placed in a tube furnace, and nitrogen is injected into the tube furnace to remove the air in the tube;

[0151] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0152] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a microcrystalline cellulose-derived carbon material, which was designated as MCC;

[0153] (4) Grind and mix DE-MCC, sodium amide, and sodium borohydride in a mass ratio of 1 / 3;

[0154] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0155] (6) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH was 7, and then dried in an oven at 120 °C for 12 h to obtain a FLPs metal-free catalyst, which was recorded as MCC-B3N3.

[0156] Specific operation steps for the selective hydrogenation of furfural using MCC-B3N3 catalyst:

[0157] (1) Weigh 0.1 g of MCC-B3N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0158] (2) After the reactor is sealed and leak-checked, the air in the reactor is evacuated with a vacuum pump and evacuated to a vacuum state. The air is then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0159] (3) Set the reaction conditions and start heating;

[0160] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0161] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0162] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0163] Comparative Example 2

[0164] (1) A certain amount of microcrystalline cellulose is placed in a tube furnace, and nitrogen is injected into the tube furnace to remove the air in the tube;

[0165] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0166] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a microcrystalline cellulose-derived carbon material, which was designated as MCC;

[0167] (4) Grind and mix the MCC obtained in step (3) with KOH in a mass ratio of 1 / 9;

[0168] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0169] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-MCC;

[0170] Specific operation steps for the selective hydrogenation of furfural using DE-MCC:

[0171] (1) Weigh 0.1 g of DE-MCC catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0172] (2) After the reactor is sealed and leak-checked, the air in the reactor is evacuated with a vacuum pump and evacuated to a vacuum state. The air is then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0173] (3) Set the reaction conditions and start heating;

[0174] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0175] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0176] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0177] Comparative Example 3

[0178] (1) A certain amount of microcrystalline cellulose is placed in a tube furnace, and nitrogen is injected into the tube furnace to remove the air in the tube;

[0179] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0180] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a microcrystalline cellulose-derived carbon material, which was designated as MCC;

[0181] (4) Grind and mix the MCC obtained in step (3) with KOH in a mass ratio of 1 / 9;

[0182] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0183] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-MCC;

[0184] (7) Grind and mix DE-MCC and sodium borohydride in a mass ratio of 1 / 3;

[0185] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0186] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH was 7, and then dried in an oven at 120 °C for 12 h to obtain a metal-free catalyst, which was designated as DE-MCC-B3.

[0187] Specific operation steps for the selective hydrogenation of furfural using DE-MCC-B3 catalyst:

[0188] (1) Weigh 0.1 g of DE-MCC-B3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0189] (2) After the reactor is sealed and leak-checked, the air in the reactor is evacuated with a vacuum pump and evacuated to a vacuum state. The air is then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0190] (3) Set the reaction conditions and start heating;

[0191] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0192] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0193] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0194] Comparative Example 4

[0195] (1) A certain amount of microcrystalline cellulose is placed in a tube furnace, and nitrogen is injected into the tube furnace to remove the air in the tube;

[0196] (2) In a nitrogen atmosphere, heat the sample to 300°C at a rate of 1°C / min, then immediately heat the sample to 800°C at a rate of 5°C / min, calcine the sample at 800°C for 2 h, and then allow the sample to cool naturally.

[0197] (3) The obtained powder was repeatedly washed with deionized water and then dried to obtain a microcrystalline cellulose-derived carbon material, which was designated as MCC;

[0198] (4) Grind and mix the MCC obtained in step (3) with KOH in a mass ratio of 1 / 9;

[0199] (5) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, calcined at 500°C for 3 h, and then allowed to cool naturally;

[0200] (6) The solid powder taken out of the tube furnace was washed with a large amount of deionized water until it did not change color when tested with Na3Co(NO2)6, thereby obtaining a defective carbon material, which was recorded as DE-MCC;

[0201] (7) Grind and mix DE-MCC and sodium amide in a mass ratio of 1 / 3;

[0202] (8) The mixed powder was placed in a tube furnace, heated to 500°C at 5°C / min in a nitrogen atmosphere, and calcined at 500°C for 1 h. Subsequently, the temperature was immediately increased to 850°C at 5°C / min, and calcined at 850°C for 2 h, and then allowed to cool naturally.

[0203] (9) The solid powder obtained in the tube furnace was repeatedly washed with a large amount of deionized water until the pH was 7, and then dried in an oven at 120 °C for 12 h to obtain the FLPs metal-free catalyst, which was recorded as DE-MCC-N3.

[0204] Specific operation steps for the selective hydrogenation of furfural using DE-MCC-N3 catalyst:

[0205] (1) Weigh 0.1 g of DE-MCC-N3 catalyst and place it in a 50 mL liner autoclave, then add 0.1 g of furfural and 10 mL of isopropanol;

[0206] (2) After the reactor is sealed and leak-checked, the air in the reactor is evacuated with a vacuum pump and evacuated to a vacuum state. The air is then replaced with nitrogen three times and filled with 0.5 MPa H2.

[0207] (3) Set the reaction conditions and start heating;

[0208] (4) When the temperature of the reactor reaches 160°C, open the main valve and the air inlet valve of the hydrogen cylinder, adjust the pressure to 2 MPa, and record the reaction start time;

[0209] (5) After the reaction is complete, close the main valve and air inlet valve of the gas cylinder and wait for the reactor to cool naturally to room temperature;

[0210] (6) The reaction solution was taken out, filtered and quantified; the product was quantitatively and qualitatively analyzed by gas chromatography.

[0211] The reaction results of the above examples and comparative examples are shown in the following table:

[0212]

[0213]

[0214] From the reaction results of the different examples in Table 1 above, it can be seen that the FLPs catalysts obtained in the different examples showed good catalytic performance for the selective hydrogenation of furfural to furfuryl alcohol. Among them, a furfuryl alcohol yield of 99.8% was obtained on the DE-MCC-B3N3 catalyst. In addition, it can be found that on the MCC-B3N3 catalyst obtained without etching, the furfural conversion rate was only 37.7%, and the furfuryl alcohol selectivity was only 62.7%, which was far inferior to the reaction effect after etching. This shows that etching is significantly beneficial to the reaction. The reason is that after etching carbon, it is conducive to the anchoring of B and N on carbon, thereby forming a large number of FLPs sites, promoting the activation of H2 and the adsorption of carbonyl groups. In addition, from the reaction results of Comparative Example 2, it can be seen that the carbon material has no promoting effect on the furfural hydrogenation reaction. It is worth noting that after anchoring B or N alone on the defective carbon material, the reaction results are not ideal, because no FLPs sites are formed.

Claims

1. A method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material, characterized in that: The steps include: S1. The biomass carbon source is calcined under a nitrogen atmosphere, washed, and dried to obtain a biomass-derived carbon material; S2. The carbon material obtained in step S1 is ground and mixed with an etchant, and then calcined and washed to obtain a defective carbon material; S3. Grind and mix the defective carbon material obtained in step S2 with a nitrogen source and a boron source, and then calcine, wash, and dry the mixture in stages to obtain a FLPs metal-free catalyst.

2. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: In step S1, the biomass carbon source includes at least one of sugars, organic acids, oils and fats, or alcohols.

3. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: Microcrystalline cellulose, soluble starch, dextrose, citric acid, resorcinol, or polyethylene glycol-6000.

4. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: In step S1, the calcination conditions are: heating to 300-400°C at 1-3°C / min, then heating to 700-900°C at 3-5°C / min and keeping the temperature for 1-3 hours.

5. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: In step S2, the etchant is KOH, NH4HCO3 or NH4CO3; the mass ratio of the carbon material to the etchant is 1:6-10; and the calcination conditions are: heating to 450-550°C at 3-5°C / min and keeping warm for 2-4h.

6. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: In step S3, the nitrogen source is sodium amide, dicyandiamide, dicyandiamide, melamine, urea or triethylenediamine, and the boron source is sodium borohydride, metaboric acid, boric acid or phenylboric acid; the mass ratio of the defective carbon material, the nitrogen source and the boron source is 1:1~3:1~3.

7. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: In step S3, the staged calcination conditions are: heating to 450-550° C. at 3-5° C. / min and keeping warm for 0.5-2 h, then heating to 850° C. at 3-5° C. / min and keeping warm for 2 h.

8. The method for preparing a metal-free catalyst for constructing FLPs on the surface of a biomass-derived carbon material according to claim 1, characterized in that: The FLPs metal-free catalyst is a defective carbon material co-doped with B and N and has FLPs active sites; the FLPs metal-free catalyst is DE-MCC-B3N3, DE-STH-B3N3, DE-GLU-B3N3, DE-CA-B3N3, DE-ROL-B3N3 or DE-PEG-B3N3.

9. Use of the FLPs metal-free catalyst obtained by the preparation method according to any one of claims 1 to 8 in the selective hydrogenation of α,β-unsaturated aldehydes to produce unsaturated alcohols.

10. The use according to claim 9, characterized in that The α,β-unsaturated aldehyde is furfural; the reaction conditions are: reaction temperature of 140-170°C, hydrogen pressure of 0.5-3MPa, reaction solvent of ethanol, methanol or isopropanol, and a mass ratio of catalyst to furfural of 1:0.5-1.5.

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